Taurine for subgroups of Autism? Plus, vitamin B5 and L Carnitine for KAT6A syndrome?

 

   A Red Bull Formula 1 racing car

 

Today’s post should be of wide interest because it concerns the potential benefit from the OTC supplement taurine. There is a section at the end answering a query about mutations in the KAT6A gene.

Taurine is an amino acid and it is found in abundance in both mother’s milk and formula milk.  It has long been used as a supplement by some people with autism. It is finally going to be the subject of a clinical trial in autism and not surprisingly that will be in China - nowadays home to much autism research.

Taurine is also a key ingredient in energy drinks like Red Bull.

 

In a study of children with autism a third had low levels of taurine. Since taurine has anti-oxidant activity, children with ASD with low taurine concentrations were then examined for abnormal mitochondrial function. That study suggests that taurine may be a valid biomarker in a subgroup of ASD.

Taurine has several potential benefits to those with autism and it is already used to treat a wide variety of other conditions, some of which are relevant to autism. One example is its use in Japan to improve mitochondrial function in a conditional called MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes).

The effects that are suggested to relate to some types of autism include:-

 

·        Activating GABA_A receptors, in the short term

·        Down regulating GABA_A receptors, after long term use

·        Enhancing the PTEN/mTOR/AKT pathway

·        Reverse autophagy impairment caused by microglial activation

·        Reduce NMDA mediated activation of calcium channels

·        Protective effect on mitochondria and upregulating Complex 1

·        Improving the quality of the gut microbiota

 

If you have a pet you may know that taurine is widely given to cats and dogs. All cat food has taurine added and some breeds of dog need supplementation.

Taurine is crucial for several bodily functions in pets, including: 

Heart Health: Taurine helps regulate heart rhythm and improves heart muscle function. It can help prevent a type of heart disease called dilated cardiomyopathy (DCM) in both cats and dogs.

Vision: Taurine plays a role in maintaining healthy vision and can prevent retinal degeneration, a serious eye disease.

Immune System Function: Taurine may help boost the immune system and fight off infections.

 

From China we have the following recent study showing a benefit in the BTBR model of autism:

Taurine Improved Autism-Like Behaviours and Defective Neurogenesis of the Hippocampus in BTBR Mice through the PTEN/mTOR/AKT Signalling Pathway

Effective treatment of patients with autism spectrum disorder (ASD) is still absent so far. Taurine exhibits therapeutic effects towards the autism-like behaviour in ASD model animals. Here, we determined the mechanism of taurine effect on hippocampal neurogenesis in genetically inbred BTBR T⁺ tf/J (BTBR) mice, a proposed model of ASD. In this ASD mouse model, we explored the effect of oral taurine supplementation on ASD-like behaviours in an open field test, elevated plus maze, marble burying test, self-grooming test, and three-chamber test. The mice were divided into four groups of normal controls (WT) and models (BTBR), who did or did not receive 6-week taurine supplementation in water (WT, WT+ Taurine, BTBR, and BTBR+Taurine). Neurogenesis-related effects were determined by Ki67 immunofluorescence staining. Western blot analysis was performed to detect the expression of phosphatase and tensin homologue deleted from chromosome 10 (PTEN)/mTOR/AKT pathway-associated proteins. Our results showed that taurine improved the autism-like behaviour, increased the proliferation of hippocampal cells, promoted PTEN expression, and reduced phosphorylation of mTOR and AKT in hippocampal tissue of the BTBR mice. In conclusion, taurine reduced the autism-like behaviour in partially inherited autism model mice, which may be associa­ted with improving the defective neural precursor cell proliferation and enhancing the PTEN-associated pathway in hippocampal tissue.

 

A trial in humans with autism is scheduled in Guizhou, China. In this trial they seem to believe the benefit may come from modification to the gut microbiota.

 

Study on the Treatment of Taurine in Children With Autism

In the treatment of autism spectrum disorders (ASD), medication is only an adjunct, and the main treatment modalities are education and behavioral therapy. People with autism incur huge medical and educational costs, which puts a great financial burden on families. Taurine is one of the abundant amino acids in tissues and organs, and plays a variety of physiological and pharmacological functions in nervous, cardiovascular, renal, endocrine and immune systems. A large number of studies have shown that taurine can improve cognitive function impairment under various physiological or pathological conditions through a variety of mechanisms, taurine can increase the abundance of beneficial bacteria in the intestine, inhibit the growth of harmful bacteria, and have a positive effect on intestinal homeostasis. This study intends to analyze the effect of taurine supplementation on ASD, and explore the possible mechanism by detecting intestinal symptoms, intestinal flora, markers of oxidative stress and clinical symptoms of ASD.

Taurine granules mixed with corn starch and white sugar, 0.4g in 1 bag, taken orally. One time dosage: 1 bag each time for 1-2 years old, 3 times a day, 1.5 bags each time for 3-5 years old, 3 times a day, 2 bags each time for 6-8 years old, 3 times a day, 2.5-3 bags each time for 9-13 years old, 3 to 4 bags each time for children and adults over 14 years old, 3 times a day. The use of taurine is strictly in accordance with the specifications of Chinese Pharmacopoeia. 

 

Roles of taurine in cognitive function of physiology, pathologies and toxication

Taurine is a key functional amino acid with many functions in the nervous system. The effects of taurine on cognitive function have aroused increasing attention. First, the fluctuations of taurine and its transporters are associated with cognitive impairments in physiology and pathology. This may help diagnose and treat cognitive impairment though mechanisms are not fully uncovered in existing studies. Then, taurine supplements in cognitive impairment of different physiologies, pathologies and toxicologies have been demonstrated to significantly improve and restore cognition in most cases. However, elevated taurine level in cerebrospinal fluid (CSF) by exogenous administration causes cognition retardations only in physiologically sensitive period between the perinatal to early postnatal period. In this review, taurine levels are summarized in different types of cognitive impairments. Subsequently, the effects of taurine supplements on cognitions in physiology, different pathologies and toxication of cognitive impairments (e.g. aging, Alzheimer' disease, streptozotocin (STZ)-induced brain damage, ischemia model, mental disorder, genetic diseases and cognitive injuries of pharmaceuticals and toxins) are analyzed. These data suggest that taurine can improve cognition function through multiple potential mechanisms (e.g. restoring functions of taurine transporters and γ-aminobutyric acid (GABA) A receptors subunit; mitigating neuroinflammation; up-regulating Nrf2 expression and antioxidant capacities; activating Akt/CREB/PGC1α pathway, and further enhancing mitochondria biogenesis, synaptic function and reducing oxidative stress; increasing neurogenesis and synaptic function by pERK; activating PKA pathway). However, more mechanisms still need explorations.

 

Effects and Mechanisms of Taurine as a Therapeutic Agent

Taurine as an inhibitory neuromodulator

Although ER stress assumes an important role in the cytoprotective actions of taurine in the central nervous system (CNS), another important mechanism affecting the CNS is the neuromodulatory activity of taurine. Toxicity in the CNS commonly occurs when an imbalance develops between excitatory and inhibitory neurotransmitters. GABA is one of the dominant inhibitory neurotransmitters, therefore, reductions in either the CNS levels of GABA or the activity of the GABA receptors can favor neuronal hyperexcitability. Taurine serves as a weak agonist of the GABA_A, glycine and NMDA receptors Therefore, taurine can partially substitute for GABA by causing inhibition of neuronal excitability. However, the regulation of the GABA_A receptor by taurine is complex. While acute taurine administration activates the GABA_A receptor, chronic taurine feeding promotes the downregulation of the GABA_A receptor  and the upregulation of glutamate decarboxylase, the rate-limiting step in GABA biosynthesis. Therefore, complex interactions within the GABAeric system, as well as in the glycine and NMDA receptors, largely define the actions of taurine in the CNS.

Pharmacological characterization of GABA_A receptors in taurine-fed mice

Background

Taurine is one of the most abundant free amino acids especially in excitable tissues, with wide physiological actions. Chronic supplementation of taurine in drinking water to mice increases brain excitability mainly through alterations in the inhibitory GABAergic system. These changes include elevated expression level of glutamic acid decarboxylase (GAD) and increased levels of GABA. Additionally we reported that GABAA receptors were down regulated with chronic administration of taurine. Here, we investigated pharmacologically the functional significance of decreased / or change in subunit composition of the GABAA receptors by determining the threshold for picrotoxin-induced seizures. Picrotoxin, an antagonist of GABAA receptors that blocks the channels while in the open state, binds within the pore of the channel between the β2 and β3 subunits. These are the same subunits to which GABA and presumably taurine binds.

Methods

Two-month-old male FVB/NJ mice were subcutaneously injected with picrotoxin (5 mg kg-1) and observed for a) latency until seizures began, b) duration of seizures, and c) frequency of seizures. For taurine treatment, mice were either fed taurine in drinking water (0.05%) or injected (43 mg/kg) 15 min prior to picrotoxin injection. 

Results

We found that taurine-fed mice are resistant to picrotoxin-induced seizures when compared to age-matched controls, as measured by increased latency to seizure, decreased occurrence of seizures and reduced mortality rate. In the picrotoxin-treated animals, latency and duration were significantly shorter than in taurine-treated animas. Injection of taurine 15 min before picrotoxin significantly delayed seizure onset, as did chronic administration of taurine in the diet. Further, taurine treatment significantly increased survival rates compared to the picrotoxin-treated mice. 

Conclusions

We suggest that the elevated threshold for picrotoxin-induced seizures in taurine-fed mice is due to the reduced binding sites available for picrotoxin binding due to the reduced expression of the beta subunits of the GABAA receptor. The delayed effects of picrotoxin after acute taurine injection may indicate that the two molecules are competing for the same binding site on the GABAA receptor. Thus, taurine-fed mice have a functional alteration in the GABAergic system. These include: increased GAD expression, increased GABA levels, and changes in subunit composition of the GABAA receptors. Such a finding is relevant in conditions where agonists of GABAA receptors, such as anesthetics, are administered.

 

Taurine as used in Japan to treat MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes)

Taurine powder 98% "Taisho" [Prevention of stroke-like episodes of MELAS]

Effects of this medicine

This medicine improves mitochondrial dysfunction related to cell energy production etc., and suppresses stroke-like episodes.
It is usually used for prevention of stroke-like episodes of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes).

·         Your dosing schedule prescribed by your doctor is ((        to be written by a healthcare professional))

·         In general, take as following dose according to your weight, 3 times a day after meals. If you weigh less than 15 kg, take 1.02 g (1 g of the active ingredient) at a time. If your weight ranges 15 kg to less than 25 kg, take 2.04 g (2 g) at a time. If your weight ranges 25 kg to less than 40 kg, take 3.06 g (3 g) at a time. If you weigh 40 kg and more, take 4.08 g (4 g) at a time. Strictly follow the instructions.

·         If you miss a dose, take the missed a dose as soon as possible. However, if it is almost time for the next dose, skip the missed a dose and continue your regular dosing schedule. You should never take two doses at one time.

·         If you accidentally take more than your prescribed dose, consult with your doctor or pharmacist.

·         Do not stop taking this medicine unless your doctor instructs you to do so.

 

On the Potential Therapeutic Roles of Taurine in Autism Spectrum Disorder

 

Contemporary research has found that people with autism spectrum disorder (ASD) exhibit aberrant immunological function, with a shift toward increased cytokine production and unusual cell function. Microglia and astroglia were found to be significantly activated in immuno-cytochemical studies, and cytokine analysis revealed that the macrophage chemoattractant protein-1 (MCP-1), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and transforming growth factor β-1 (TGFB-1), all generated in the neuroglia, constituted the most predominant cytokines in the brain. Taurine (2-aminoethanesulfonic acid) is a promising therapeutic molecule able to increase the activity of antioxidant enzymes and ATPase, which may be protective against aluminum-induced neurotoxicity. It can also stimulate neurogenesis, synaptogenesis, and reprogramming of proinflammatory M1 macrophage polarization by decreasing mitophagy (mitochondrial autophagy) and raising the expression of the markers of the anti-inflammatory and pro-healing M2 macrophages, such as macrophage mannose receptor (MMR, CD206) and interleukin 10 (IL-10), while lowering the expression of the M1 inflammatory factor genes. Taurine also induces autophagy, which is a mechanism that is impaired in microglia cells and is critically associated with the pathophysiology of ASD. We hypothesize here that taurine could reprogram the metabolism of M1 macrophages that are overstimulated in the nervous system of people suffering from ASD, thereby decreasing the neuroinflammatory process characterized by autophagy impairment (due to excessive microglia activation), neuronal death, and improving cognitive functions. Therefore, we suggest that taurine can serve as an important lead for the development of novel drugs for ASD treatment.

  

Taurine as a potential therapeutic agent interacting with multiple signaling pathways implicated in autism spectrum disorder (ASD): An in-silico analysis

  

Autism spectrum disorders (ASD) are a complex sequelae of neurodevelopmental disorders which manifest in the form of communication and social deficits. Currently, only two agents, namely risperidone and aripiprazole have been approved for the treatment of ASD, and there is a dearth of more drugs for the disorder. The exact pathophysiology of autism is not understood clearly, but research has implicated multiple pathways at different points in the neuronal circuitry, suggesting their role in ASD. Among these, the role played by neuroinflammatory cascades like the NF-KB and Nrf2 pathways, and the excitotoxic glutamatergic system, are said to have a bearing on the development of ASD. Similarly, the GPR40 receptor, present in both the gut and the blood brain barrier, has also been said to be involved in the disorder. Consequently, molecules which can act by interacting with one or multiple of these targets might have a potential in the therapy of the disorder, and for this reason, this study was designed to assess the binding affinity of taurine, a naturally-occurring amino acid, with these target molecules. The same was scored against these targets using in-silico docking studies, with Risperidone and Aripiprazole being used as standard comparators. Encouraging docking scores were obtained for taurine across all the selected targets, indicating promising target interaction. But the affinity for targets actually varied in the order NRF-KEAP > NF-κB > NMDA > Calcium channel > GPR 40. Given the potential implication of these targets in the pathogenesis of ASD, the drug might show promising results in the therapy of the disorder if subjected to further evaluations.

 

Is Taurine a Biomarker in Autistic Spectrum Disorder?

Taurine is a sulfur-containing amino acid which is not incorporated into protein. However, taurine has various critical physiological functions including development of the eye and brain, reproduction, osmoregulation, and immune functions including anti-inflammatory as well as anti-oxidant activity. The causes of autistic spectrum disorder (ASD) are not clear but a high heritability implicates an important role for genetic factors. Reports also implicate oxidative stress and inflammation in the etiology of ASD. Thus, taurine, a well-known antioxidant and regulator of inflammation, was investigated here using the sera from both girls and boys with ASD as well as their siblings and parents. Previous reports regarding taurine serum concentrations in ASD from various laboratories have been controversial. To address the potential role of taurine in ASD, we collected sera from 66 children with ASD (males: 45; females: 21, age 1.5-11.5 years, average age 5.2 ± 1.6) as well as their unaffected siblings (brothers: 24; sisters: 32, age 1.5-17 years, average age 7.0 ± 2.0) as controls of the children with ASD along with parents (fathers: 49; mothers: 54, age 28-45 years). The sera from normal adult controls (males: 47; females: 51, age 28-48 years) were used as controls for the parents. Taurine concentrations in all sera samples were measured using high performance liquid chromatography (HPLC) using a phenylisothiocyanate labeling technique. Taurine concentrations from female and male children with ASD were 123.8 ± 15.2 and 145.8 ± 8.1 μM, respectively, and those from their unaffected brothers and sisters were 142.6 ± 10.4 and 150.8 ± 8.4 μM, respectively. There was no significant difference in taurine concentration between autistic children and their unaffected siblings. Taurine concentrations in children with ASD were also not significantly different from their parents (mothers: 139.6 ± 7.7 μM, fathers: 147.4 ± 7.5 μM). No significant difference was observed between adult controls and parents of ASD children (control females: 164.8 ± 4.8 μM, control males: 163.0 ± 7.0 μM). However, 21 out of 66 children with ASD had low taurine concentrations (<106 μM). Since taurine has anti-oxidant activity, children with ASD with low taurine concentrations will be examined for abnormal mitochondrial function. Our data imply that taurine may be a valid biomarker in a subgroup of ASD.

  

The Role of Taurine in Mitochondria Health: More Than Just an Antioxidant

Taurine is a naturally occurring sulfur-containing amino acid that is found abundantly in excitatory tissues, such as the heart, brain, retina and skeletal muscles. Taurine was first isolated in the 1800s, but not much was known about this molecule until the 1990s. In 1985, taurine was first approved as the treatment among heart failure patients in Japan. Accumulating studies have shown that taurine supplementation also protects against pathologies associated with mitochondrial defects, such as aging, mitochondrial diseases, metabolic syndrome, cancer, cardiovascular diseases and neurological disorders. In this review, we will provide a general overview on the mitochondria biology and the consequence of mitochondrial defects in pathologies. Then, we will discuss the antioxidant action of taurine, particularly in relation to the maintenance of mitochondria function. We will also describe several reported studies on the current use of taurine supplementation in several mitochondria-associated pathologies in humans.

 

Taurine is known not as a radical scavenger. Several potential mechanisms by which taurine exerts its antioxidant activity in maintaining mitochondria health include: taurine conjugates with uridine on mitochondrial tRNA to form a 5-taurinomethyluridine for proper synthesis of mitochondrial proteins (mechanism 1), which regulates the stability and functionality of respiratory chain complexes; taurine reduces superoxide generation by enhancing the activity of intracellular antioxidants (mechanism 2); taurine prevents calcium overload and prevents reduction in energy production and the collapse of mitochondrial membrane potential (mechanism 3); taurine directly scavenges HOCl to form N-chlorotaurine in inhibiting a pro-inflammatory response (mechanism 4); and taurine inhibits mitochondria-mediated apoptosis by preventing caspase activation or by restoring the Bax/Bcl-2 ratio and preventing Bax translocation to the mitochondria to promote apoptosis (mechanism 5).

Taurine Forms a Complex with Mitochondrial tRNA

Taurine Reduces Superoxide Generation in the Mitochondria

Taurine Regulates Intracellular Calcium Homeostasis

Taurine Inhibits Mitochondria-Mediated Apoptosis

 

Taurine therapy, therefore, could potentially improve mitochondrial health, particularly in mitochondria-targeted pathologies, such as cardiovascular diseases, metabolic diseases, mitochondrial diseases and neurological disorders. Whether the protective mechanism on mitochondria primarily relies on the taurine modification of mitochondrial tRNA requires further investigation.

 

Taurine and the gut microbiota 

We now regularly in the research see that you can make changes in the gut microbiota to treat medical conditions. I think the most interesting was the discovery that the ketogenic diet, used for a century to treat epilepsy, actually works via the high fat diet changing the bacteria that live in your gut; it has nothing at all to do with ketones. UCLA are developing a bacteria product that will mimic the effect of this diet.

We should not be surprised to see that one mode of action put forward for Taurine is changes it makes in the gut microbiota.  It is this very mechanism that the Chinese researchers think is relevant to its benefit in autism.

The paper below is not about autism, but it is about Taurine’s effect on the gut microbiota.

Effects of Taurine on Gut Microbiota Homeostasis: An Evaluation Based on Two Models of Gut Dysbiosis

Taurine, an abundant free amino acid, plays multiple roles in the body, including bile acid conjugation, osmoregulation, oxidative stress, and inflammation prevention. Although the relationship between taurine and the gut has been briefly described, the effects of taurine on the reconstitution of intestinal flora homeostasis under conditions of gut dysbiosis and underlying mechanisms remain unclear. This study examined the effects of taurine on the intestinal flora and homeostasis of healthy mice and mice with dysbiosis caused by antibiotic treatment and pathogenic bacterial infections. The results showed that taurine supplementation could significantly regulate intestinal microflora, alter fecal bile acid composition, reverse the decrease in Lactobacillus abundance, boost intestinal immunity in response to antibiotic exposure, resist colonization by Citrobacter rodentium, and enhance the diversity of flora during infection. Our results indicate that taurine has the potential to shape the gut microbiota of mice and positively affect the restoration of intestinal homeostasis. Thus, taurine can be utilized as a targeted regulator to re-establish a normal microenvironment and to treat or prevent gut dysbiosis.

  

Conclusion

Your body can synthesize taurine from other amino acids, particularly cysteine, with the help of vitamin B6. In most cases, this internal production is enough to meet your daily needs for basic bodily functions.

Infants and some adults may need taurine added to their diet.

Based on the small study in humans, about a third of children with autism have low levels of taurine in their blood.

Is extra taurine going to provide a benefit to the other two thirds?

Taurine looks easy to trial. It is normally taken three times a day after a meal. Each dose would be 0.4g to 4g depending on weight and what the purpose was. The 2 year olds in the Chinese autism trial will be taking 0.4g three times a day. Japanese adults with mitochondrial disease (MELAS) are taking 4g three times a day.

One can oF Red Bull contains 1g of taurine. Most supplements contain 0.5 to 1g. This is a similar dose to what is given to pet cats and dogs. Just like Red Bull contains B vitamins, so do the taurine products for cats and dogs. 

Some of the effects will be immediate, while others will take time to show effect. For example there can potentially be an increase in mitochondrial biogenesis. I expect any changes in gut bacteria would also take a long time to get established.

The effect via GABA on increasing brain excitability is an interesting one for people taking bumetanide for autism, where the GABA developmental switch did not take place. Based on the research you could argue that it will be beneficial or indeed harmful.

What I can say is that in Monty, aged 20 with ASD and taking bumetanide for 12 years, he responded very well on the rare occasions he drank Red Bull.

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Vitamin B5 and L carnitine for KATA6A Syndrome

I was asked about KATA6A syndrome recently.  This syndrome is researched by Dr Kelley, the same doctor who coined the term Autism secondary to mitochondrial dysfunction (AMD).

KAT6A Research and Treatment An Update by Richard I Kelley , MD, PHD

Some kids with KATA6A, like Peter below, respond very well to Dr Kelley’s mito cocktail.

 

Peter’s Experience with a Mitochondrial Cocktail

 

Here’s my experience with the mitochondrial cocktail:

– At 4 weeks after the start of the cocktail, Peter became potty-trained during the day without any training. He pulled his pull up off, refused to put it back on.

-At 2 months, Peter started riding his bike with no training wheels and playing soccer. He became able to kick the ball and run after it till he scores.

-At 2.5 months, he started skiing independently. I used to try to teach how to ski since he was 3yo. I used to spend hours and hours picking him up off the snow with no result. I tried different kind of reinforcers (food,..) with no result. After the cocktail, he just went down the hill by himself, He can ski independently now and knows how to make turns.

-At 2-3 months, I started noticing an increased strength in playing ice hockey and street hockey with a better understanding of the game. His typing ability improved too, he used to have severe apraxia while typing (type the letter next to the letter he wants to type…).

-At 3-4 months, Peter’s fingers on the piano became stronger, he became able to play harder songs with less training and less frustration. I also noticed an increase in “common sense” like for example putting his backpack in the car instead of throwing it on the floor next to the car and riding the car without his backpack. Another example, when we go to the public library, he knows by himself that he has to go to the children section, and walks independently without showing him directions to the play area inside the children section. In the past, he used to grab books the time he enters the library, throw a tantrum on the floor. The most important milestone is that Peter started to say few words that I can understand.

-At 11 months, Peter became potty-trained at night. His speech is slowly getting clearer. His fine and gross motor skills are still getting better.

 

Some readers of this blog have been in touch with Dr Kelley and he does give very thorough replies.

Generally speaking, the therapies for mitochondrial diseases/dysfunctions seem to be about avoiding it getting worse, rather than making dramatic improvements. In the case of Peter (above) the effects do look dramatic. There are many other ideas in the research that do not seem to have been translated into therapy.

A study from two years ago does suggest that vitamin B5 and L carnitine should be trialed. 

Pantothenate and L-Carnitine Supplementation Improves Pathological Alterations in Cellular Models of KAT6A Syndrome

Mutations in several genes involved in the epigenetic regulation of gene expression have been considered risk alterations to different intellectual disability (ID) syndromes associated with features of autism spectrum disorder (ASD). Among them are the pathogenic variants of the lysine-acetyltransferase 6A (KAT6A) gene, which causes KAT6A syndrome. The KAT6A enzyme participates in a wide range of critical cellular functions, such as chromatin remodeling, gene expression, protein synthesis, cell metabolism, and replication. In this manuscript, we examined the pathophysiological alterations in fibroblasts derived from three patients harboring KAT6A mutations. We addressed survival in a stress medium, histone acetylation, protein expression patterns, and transcriptome analysis, as well as cell bioenergetics. In addition, we evaluated the therapeutic effectiveness of epigenetic modulators and mitochondrial boosting agents, such as pantothenate and L-carnitine, in correcting the mutant phenotype. Pantothenate and L-carnitine treatment increased histone acetylation and partially corrected protein and transcriptomic expression patterns in mutant KAT6A cells. Furthermore, the cell bioenergetics of mutant cells was significantly improved. Our results suggest that pantothenate and L-carnitine can significantly improve the mutant phenotype in cellular models of KAT6A syndrome.

Next, we analyzed the expression changes of specific genes in treated and untreated conditions. We found that the expression levels of downregulated genes in the mutant KAT6A fibroblasts, such as KAT6A, SIRT1, SIRT3, NAMPT1, Mt-ND6, NDUFA9, PANK2, mtACP, PDH (E1 subunit α2), KGDH (E2 subunit), SOD1, SOD2, and GPX4 were significantly restored after pantothenate and L-carnitine treatment. The proteins encoded by these genes are involved in acetylation-deacetylation pathways, CoA metabolism, mitochondria, and antioxidant enzymes, all of which are critical for intracellular processes in embryonic and childhood development.

 

KAT6A acts as a master regulator by fine-tuning gene expression through chromatin modifications, so we should expect it to have wide ranging effects. All the closest interactions are will other genes that modify gene expression.

 

https://string-db.org/cgi/network?taskId=b9YRZJrlHtMF&sessionId=b1EyJebcKvBK

A useful site is genecards:

https://www.genecards.org/cgi-bin/carddisp.pl?gene=KAT6A

 

KAT6A mutations are indeed linked to microcephaly, a condition characterized by a smaller than average head circumference.

Most autism is associated with hyperactive pro-growth signalling pathways; only a minority is associated with the opposite and this would fit with microcephaly, which is typical in KAT6A.

Microcephaly is a very common feature of Rett syndrome.

Among the features of KAT6A syndrome there will be overlaps with other syndromes.

Dr Kelley analyses amino acids looking for mitochondrial dysfunction. He has found this present in KAT6A, but this is only one treatable feature of the syndrome.

Targeting growth signaling pathways might well be worth pursuing. You would be looking a what works in other people with smaller heads.

I wrote quite a lot about IGF-1 previously in this blog.

It would be highly plausible that these related therapies might be of benefit. The easy one to try is cGPMax, because it is sold OTC. IGF-1 itself might be beneficial, you would have to find a helpful endocrinologist to trial it.

All the therapies of idiopathic autism could be trialed.

If the child has a paradoxical reaction to any benzodiazepine drug, then you know that bumetanide is likely to be beneficial.

Since mitochondrial function is impaired in KAT6A, taurine is another thing to trial.

Learning from GABAa Dysfunction in Huntington’s Disease – useful ideas for Autism therapies?

Today’s post is really for the regular readers of this blog who are interested in the GABA switch and Bumetanide. It is not light reading.  We see how advanced some Taiwanese researchers are in their understanding of GABA_A dysfunctions in Huntington’s Disease.

Taipei 101, briefly the world’s tallest building

It is an excellent paper and much of it is applicable to autism. There are some omissions, but you will struggle to find a more complete paper.

They even go into the detail of altered the sub-unit expression of GABA_A receptors that occurs as the disease progresses. I think that correcting sub-unit miss-expression has great potential in treating some autism.

Huntington’s is an inherited brain disorder that first manifests itself around the age of 40 and then progresses for the next 15 to 20 years.

Much autism is present prior to birth but there is a progression that occurs as the brain develops in early childhood. Some people do seem to be entirely typical at birth and only around 2 years old develop symptoms. After 5 years old you cannot really develop “autism”, just the symptoms might not get noticed till later in life.

Schizophrenia only develops in early to mid-adulthood.

It is surprising to many people that such varied disorders share some similar aspects of biology.

In terms of practical interventions, in today’s paper these include:       

·        Inhibition of NKCC1 (bumetanide)

·        Activation of KCC2 (N-Ethylmaleimide)

·        Enhancer of CKB (creatine)

·        Inhibitor of WNK/SPAK

·        Activation of extra-synaptic GABAa receptors (taurine, progesterone)

·        Activation of synaptic GABAa receptors (zolpidem, alprazolam)

·        Inhibition of GABA transport mechanism (Tiagabine)

One thing to note is that activating GABAa receptors may well have a negative effect in some people.

Sub-unit specific therapies, like very low dose clonazepam targeting α3, are not mentioned in this paper, nor is the role of GABAb on NKCC1/KCC2 expression.

We are familiar with Bumetanide as an NKCC1 blocker intervention in autism, but looking at the list there are other common autism therapies (creatine and taurine) and the female hormone progesterone. We come upon the beneficial effect of female hormones on a regular basis in this blog (estradiol, pregnenalone, progesterone …).  We even saw how a sub-SSRI dose of Prozac increases the amount of the neurosteroid 3α-hydroxy-5α-pregnan-20-one (Allo) that potently, positively, and allosterically modulates GABA action at GABA_A receptors. Progesterone is converted to Allo in the body.

 

Here is the excellent paper on Huntington’s:-

Insights into GABAAergic system alteration in Huntington’s disease

                                                                                                               

An overview of the g-aminobutyric acid (GABA) signalling system. (a) GABA homeostasis is regulated by neurons and astrocytes. GABA is synthesized by GAD65/67 from glutamate in neurons, while astrocytic GABA is synthesized through MAOB. The release of GABA is mediated by membrane depolarization in neurons and Best1 in astrocytes. The reuptake of GABA is mediated through GAT1 in neurons and GAT3 in astrocytes. The metabolism of GABA is mediated by GABA-T in neurons and astrocytes. The reuptake of GABA in astrocytes is further transformed into glutamine via the TCA cycle and glutamine synthetase (GS). The glutamine is then transported to neurons and converted to glutamate for regeneration of GABA.

(b) GABAA receptors are heteropentameric complexes assembled from 19 different subunits. The compositions of different subunits determines the subcellular distributions and functional properties of the receptors. Phasic inhibition is mediated via the activation of synaptic GABAA receptors following brief exposure to a high concentration of extracellular GABA. Tonic inhibition is mediated via the activation of extrasynaptic GABAA receptors by a low concentration of ambient GABA.

c) The excitatory inhibitory response of GABA is driven by the chloride gradient across cell membranes, which can be determined via two cation–chloride cotransporters (NKCC1 and KCC2). The high expression of NKCC1 during the developmental stage maintains higher intracellular [Cl2] via chloride influx to the cell. The activation of GABAA receptors at an early developmental stage results in an outward flow of chloride and an excitatory GABAergic response. As neurons mature, the high expression of KCC2 maintains lower intracellular [Cl2] via chloride efflux out of the cell. The activation of GABAA receptors on mature neurons results in the inward flow of chloride and an inhibitory GABAergic response.

An excerpt showing data on sub-unit misexpression in different parts of the brain at different stages of the disease

5.2. Modulation of chloride homeostasis via cation – chloride cotransporters

Emerging evidence suggests that chloride homeostasis is a therapeutic target for HD. Pharmacological agents that target cation–chloride cotransporters (i.e. NKCC1 or KCC2) therefore might be used to treat HD (figure 3b). Of note, dysregulation of cation–chloride cotransporters and GABA polarity was associated with several neuropsychiatric disorders [70,134–139] (reviewed in [27,140]). Such abnormal excitatory GABAA receptor neurotransmission can be rescued by bumetanide, an NKCC1 inhibitor that decreases intracellular chloride concentration. Bumetanide is an FDA-approved diuretic agent that has been used in the clinic. It attenuates many neurological and psychiatric disorders in preclinical studies and some clinical trials for traumatic brain injury, seizure, chronic pain, cerebral infarction, Down syndrome, schizophrenia, fragile X syndrome and autism (reviewed in [141]). Daily intraperitoneal injections of bumetanide also restored the impaired motor function of HD mice. The effect of bumetanide is likely to be mediated by NKCC1 because genetic ablation of NKCC1 in the striatum also rescued the motor deficits in R6/2 mice. This study uncovered a previously unrecognized depolarizing or excitatory action of GABA in the aberrant motor control in HD. In addition, chronic treatment with bumetanide also improved the impaired memory in R6/2 mice [69], supporting the importance of NKCC1 in HD pathogenesis. Owing to the poor ability of bumetanide to pass through the blood–brain barrier, further optimization of bumetanide and other NKCC1 inhibitors is warranted [142,143]. Disruption of KCC2 function is detrimental to inhibitory transmission and agents to activate KCC2 function would be beneficial in HD. However, no agonist of KCC2 has been described until very recently [144,145]. A new KCC2 agonist (CLP290) has been shown to facilitate functional recovery after spinal cord injury [145]. It would be of great interest to evaluate the effect of KCC2 agonists on HD progression. Another KCC2 activator, CLP257, was found to increase the cell surface expression of KCC2 in a rat model of neuropathic pain [146]. Post-translational modification of KCC2 by kinases may modulate the function of KCC2. The WNK/ SPAK kinase complex, composed of WNK (with no lysine) and SPAK (SPS1-related proline/alanine-rich kinase), is known to phosphorylate and stimulate NKCC1 or inhibit KCC2 [147]. Thus, compounds that inhibit WNK/SPAK kinases will result in KCC2 activation and NKCC1 inhibition. Some compounds have been noted as potential inhibitors of WNK/SPAK kinases and need to be further tested for their effects on cation –chloride cotransporters [148–150]. An alternative mechanism to activate KCC2 is manipulation of its interacting proteins (e.g. CKB [65,66]). Because CKB could activate the function of KCC2 [65,66], CKB enhancers may increase the function of KCC2. In HD, reduced expression and activity of CKB is associated with motor deficits and hearing impairment [68,88]. Enhancing CKB activity by creatine supplements ameliorated the motor deficits and hearing impairment of HD mice. It is worthwhile to further investigate the interaction of KCC2 and CKB in GABAergic neurotransmission and motor deficits in HD. The depolarizing GABA action with altered expression levels of NKCC1 or KCC2 is associated with neuroinflammation in HD brains [32,69]. Blockade of TNF-a using Xpro1595 (a dominant negative inhibitor of soluble TNF-a) [151] in vivo led to significant beneficial effects on disease progression in HD mice [152] and reduced the expression of NKCC1. It would be of great interest to test the effect of other anti-inflammatory agents [153] on the function and expression of NKCC1 and GABAergic inhibition. Neuroinflammation is implicated in most neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease [154,155], and the interaction of cation–chloride cotransporters and neuroinflammation in GABAergic neurotransmission may also play a critical role in other neurodegenerative diseases.

Figure 2. Molecular mechanism(s) underlying the abnormal GABAAergic system in HD. (a) In the normal condition, adult neurons express high KCC2 and few NKCC1 to maintain the lower intracellular chloride concentration, which results in an inward flow of chloride when GABAA receptors are activated. Astrocytes function normally for the homeostasis of glutamate, potassium and glutamate/GABA-glutamine cycle. (b) In Huntington’s disease, reduced GABAA receptor-mediated neuronal inhibition is associated with enhanced NKCC1 expression and a decreased expression in KCC2 and membrane localized GABAA receptors. The dysregulated GABAAergic system might be caused by mutant HTT, excitotoxicity, neuroinflammation or other factors. Mutant HTT in neurons alters the transcription of genes (GABAAR and KCC2) through interactions with transcriptional activators (SP1) and repressors (REST/NRSF). Mutant HTT in neurons also disrupts the intracellular trafficking of GABAARs to the cellular membrane. HD astrocytes have impaired homeostasis of extracellular potassium/glutamate (due to deficits of astrocytic Kir4.1 channel and glutamate transporters, Glt-1) and cause neuronal excitability, which might be related to the changes of KCC2, NKCC1 and GABAAR. The activity of KCC2 could be affected through its interacting proteins, such as CKB and mHTT. Neuroinflammation, which is evoked by the interaction of HD astrocyte and microglia, enhances NKCC1 expression in neurons at the transcriptional level through an NF-kB-dependent pathway. HD astrocytes also have compromised astrocytic metabolism of glutamate/GABA–glutamine cycle that contributes to lower GABA synthesis.

Notably, neuroinflammation and the GABA neurotransmitter system are reciprocally regulated in the brain (reviewed in [104,105]). Specifically, neuroinflammation induces changes in the GABA neurotransmitter system, such as reduced GABAA receptor subunit expression, while activation

of GABAA receptors likely antagonizes inflammation.

TNF-a, a proinflammatory cytokine, induces a downregulation of the surface expression of GABAARs containing a1, a2, b2/3 and g2 subunits and a decrease in inhibitory synaptic strength in a cellular model of hippocampal neuron culture [106]. The same group further demonstrated that protein phosphatase 1-dependent trafficking of GABAARs was involved in the TNF-a evoked downregulation of GABAergic neurotransmission [107]. Upregulation of TNF-a also negatively impacts the expression of GABAAR a2 subunit mRNA and thus decreases the presynaptic inhibition in the dorsal root ganglion in a rat experimental neuropathic painmodel [108]. Conversely, blockade of central GABAARs in mice by aGABAAR antagonist increased both the basal and restraint stress-induced plasma IL-6 levels [109]. Inhibition of GABAAR activation by picrotoxin increased the nuclear translocation of NF-kB in acute hippocampal slice preparations [110]. Collectively, neuroinflammation

weakens the inhibitory synaptic strength in neurons, at least partly, through the reduction of GABAARs.

The reduced expression and function of GABAARs may further increase inflammatory responses. It remains elusive whether the same mechanism occurs in the inflammatory environment in HD brains.

hyperexcitability resulting from deficiency of astrocytic Kir4.1 might have also contributed to neuronal NKCC1 upregulation and altered GABAergic signalling in HD brains.

Figure 3. Strategy to target (a) GABAAR and (b) cation–chloride cotransporters as potential therapeutic avenues. (a) The GABAergic system is influenced directly by agents that (1) target synaptic GABAAR, (2) increase tonic GABA current or interfere with synaptic GABA concentrations via a reduction of GABA reuptake (3), and (4) block GABA metabolism.

5.1. Modulating the GABAA receptor as a therapeutic target

In view of the presently discovered HD-related deficit in the GABA system, the question arises whether HD patients can benefit from drugs that stimulate the GABA system (figure 3a). HD patients suffer from motor abnormalities and

non-motor symptoms, including cognitive deficits, psychiatric symptoms, sleep disturbance, irritability, anxiety, depression and an increased incidence of seizures [74,77,116,117].

Seizures are a well-established part of juvenile HD but no more prevalent in adult-onset HD than in the general population [73,74,118]. Several pharmacological compounds can enhance inhibitory GABAergic neurotransmission by targeting GABAAR and thereby producing sedative, anxiolytic, anticonvulsant and muscle-relaxant effects. A recent study demonstrated that zolpidem, a GABAAR modulator that enhances GABA inhibition mainly via the a1-containing GABAA receptors, corrected sleep disturbance and electroencephalographic abnormalities in symptomatic HD mice (R6/2) [119]. Alprazolam, a benzodiazepine-activating GABA receptor, reversed the dysregulated circadian rhythms and improved cognitive performance of HD mice (R6/2) [120].

In addition, progesterone, a positive modulator of GABAAR, significantly reversed the behavioural impairment in a 3-nitropropionic acid (3-NP)-induced HD rat model [121]. Apart from modulating the activity of the GABAergic system by interfering directly with the receptor, pharmacological agents can also interfere with synaptic GABA concentrations. Tiagabine, a drug that specifically blocks the GABA transporter (GAT1) to increase synaptic GABA level,was found to improve motor performance and extend survival inN171-82Q and R6/2 mice [122]. It is also worth evaluating whether vigabatrin, a GABA-T inhibitor that blocksGABAcatabolismin neurons and astrocytes [123], plays a role in the compromised astrocytic glutamate–GABA–glutamine cycling [56]. Interestingly, taurine exerted GABAA agonistic and antioxidant activities in a 3-NP HD model and improved locomotor deficits and increased GABA levels [124]. However, several early studies failed to provide the expected benefits of GABA analogues in slowing disease progression in HD patients [125–127]. For example, gaboxadol, an agonist for the extrasynaptic d-containing GABAA receptor, failed to improve the decline in cognitive and motor functions of five HD patients during a short two-week trial, but it caused side effects at the maximal dose [125]. Interestingly, although treatment with muscimol (a potent agonist of GABA receptors) did not improve motor or cognitive deficits in 10HDpatients, it did ameliorate chorea in the most severely hyperkinetic patient [126]. The therapeutic failure of GABA stimulation in early clinical trials does not argue against the importance of GABAergic deficits in HD pathogenesis. The alteration of GABAergic circuits plays a primary role or is a compensatory response to excitotoxicity, and it may contribute to HD by disrupting the balance between the excitation and inhibition systems and the overall functions of neuronal circuits. Because the subunits of the GABAA receptor are brain region- or neuron subtypespecific, the choice of drugs may have distinct effects on the brain region or neuronal population targeted [128–130]. For example, the expression of GABAAR subunits is differentially altered in MSNs and other striatal interneurons in HD 54,60]. The early involvement of D2-expressing MSNs can cause chorea [131], while dysfunctional PV-expressing interneurons can cause dystonia in HD patients [132]. Specific alteration in neuronal populations and receptor subtypes during HD progression needs to be taken into consideration when treating the dysfunction of GABAergic circuitry.

Notably, striatal tonic inhibition mediated by the dcontaining GABAARs may have neuroprotective effects against excitotoxicity in the adult striatum [63]. Because the reductions in d-containing GABAARs and tonic GABA currents in D2-expressing MSNs have been observed in early HD [32,39,40,54,61], it would be of great interest to evaluate the effects of several available compounds, such as alphaxalone and ganaxolone [133], that target d-containing GABAARs, in animal models of HD.

(b) GABAAR-mediated signalling in HD neurons is depolarizing due to the high intracellular chloride concentration caused by high NKCC1 expression and low KCC2 expression. Rescuing the function of cation–chloride cotransporters can occur via (1) inhibition of NKCC1 activity using bumetanide, (2, 3) increase in KCC2 function using a KCC2 activator or CKB enhancer, and (4) inhibitors of WNK/SPAK kinases.

5.2. Modulation of chloride homeostasis via cation–chloride cotransporters

Emerging evidence suggests that chloride homeostasis is a therapeutic target for HD. Pharmacological agents that target cation–chloride cotransporters (i.e.NKCC1 orKCC2) therefore might be used to treat HD (figure 3b). Of note, dysregulation of cation–chloride cotransporters and GABA polarity was associated with several neuropsychiatric disorders [70,134–139] (reviewed in [27,140]). Such abnormal   receptor neurotransmission can be rescued by bumetanide, an NKCC1 inhibitor that decreases intracellular chloride concentration. Bumetanide is an FDA-approved diuretic agent that has been used in the clinic. It attenuates many neurological and psychiatric disorders in preclinical studies and some clinical trials for traumatic brain injury, seizure, chronic pain, cerebral infarction, Down syndrome, schizophrenia, fragile X syndrome and autism (reviewed in [141]). Daily intraperitoneal injections of bumetanide also restored the impaired motor function ofHDmice (R6/2, Y-T Hsu,Y-GChang, Y-CLi, K-YWang, H-MChen, D-J Lee, C-HTsai, C-C Lien,YChern 2018, personal communication). The effect of bumetanide is likely to be mediated by NKCC1 because genetic ablation of NKCC1 in the striatum also rescued the motor deficits in R6/2 mice (Y-T Hsu, Y-G Chang, Y-C Li, K-Y Wang, H-M Chen, D-J Lee, C-H Tsai, C-C Lien, Y Chern 2018, personal communication). This study uncovered a previously unrecognized depolarizing or excitatory action of GABA in the aberrant motor control in HD. In addition, chronic treatment with bumetanide also improved the impaired memory in R6/2 mice [69], supporting the importance of NKCC1 in HD pathogenesis. Owing to the poor ability of bumetanide to pass through the blood–brain barrier, further optimization of bumetanide and other NKCC1 inhibitors is warranted [142,143].

Disruption of KCC2 function is detrimental to inhibitory transmission and agents to activate KCC2 function would be beneficial in HD. However, no agonist of KCC2 has been described until very recently [144,145]. A new KCC2 agonist (CLP290) has been shown to facilitate functional recovery after spinal cord injury [145]. It would be of great interest to evaluate the effect of KCC2 agonists on HD progression. Another KCC2 activator, CLP257, was found to increase the cell surface expression of KCC2 in a rat model of neuropathic pain [146]. Post-translational modification of KCC2 by kinases may modulate the function of KCC2. The WNK/SPAK kinase complex, composed of WNK (with no lysine) and SPAK (SPS1-related proline/alanine-rich kinase), is known to phosphorylate and stimulate NKCC1 or inhibit KCC2 [147]. Thus, compounds that inhibit WNK/SPAK kinases will result in KCC2 activation and NKCC1 inhibition.

Some compounds have been noted as potential inhibitors of WNK/SPAK kinases and need to be further tested for their effects on cation–chloride cotransporters [148–150]. An alternative mechanism to activate KCC2 is manipulation of its interacting proteins (e.g. CKB [65,66]). Because CKB could activate the function of KCC2 [65,66], CKB enhancers may increase the function of KCC2. In HD, reduced expression and activity of CKB is associated with motor deficits and hearing impairment [68,88]. Enhancing CKB activity by creatine supplements ameliorated the motor deficits and hearing impairment of HD mice. It is worthwhile to further investigate the interaction of KCC2 and CKB in GABAergic neurotransmission and motor deficits in HD. The depolarizing GABA action with altered expression levels of NKCC1 or KCC2 is associated with neuroinflammation in HD brains [32,69]. Blockade of TNF-a using Xpro1595 (a dominant negative inhibitor of soluble TNF-a) [151] in vivo led to significant beneficial effects on disease progression in HD mice [152] and reduced the expression of NKCC1It would be of great interest to test the effect of other anti-inflammatory agents [153] on the function and expression of NKCC1 and GABAergic inhibition. Neuroinflammation is implicated in most neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease [154,155], and the interaction of cation–chloride cotransporters and neuroinflammation in GABAergic neurotransmission may also play a critical role in other neurodegenerative diseases.

Chloride extrusion enhancers as novel therapeutics for neurological diseases

Discovery of Novel SPAK Inhibitors That Block WNK Kinase Signaling to Cation Chloride Transporters

Upon activation by with-no-lysine kinases, STE20/SPS1-related proline–alanine-rich protein kinase (SPAK) phosphorylates and activates SLC12A transporters such as the Na⁺-Cl⁻ cotransporter (NCC) and Na⁺-K⁺-2Cl⁻ cotransporter type 1 (NKCC1) and type 2 (NKCC2); these transporters have important roles in regulating BP through NaCl reabsorption and vasoconstriction. SPAK knockout mice are viable and display hypotension with decreased activity (phosphorylation) of NCC and NKCC1 in the kidneys and aorta, respectively. Therefore, agents that inhibit SPAK activity could be a new class of antihypertensive drugs with dual actions (i.e., NaCl diuresis and vasodilation). In this study, we developed a new ELISA-based screening system to find novel SPAK inhibitors and screened >20,000 small-molecule compounds. Furthermore, we used a drug repositioning strategy to identify existing drugs that inhibit SPAK activity. As a result, we discovered one small-molecule compound (Stock 1S-14279) and an antiparasitic agent (Closantel) that inhibited SPAK-regulated phosphorylation and activation of NCC and NKCC1 in vitro and in mice. Notably, these compounds had structural similarity and inhibited SPAK in an ATP-insensitive manner. We propose that the two compounds found in this study may have great potential as novel antihypertensive drugs.

Chemical library screening for WNK signalling inhibitors using fluorescence correlation spectroscopy.

WNKs (with-no-lysine kinases) are the causative genes of a hereditary hypertensive disease, PHAII (pseudohypoaldosteronism type II), and form a signal cascade with OSR1 (oxidative stress-responsive 1)/SPAK (STE20/SPS1-related proline/alanine-rich protein kinase) and Slc12a (solute carrier family 12) transporters. We have shown that this signal cascade regulates blood pressure by controlling vascular tone as well as renal NaCl excretion. Therefore agents that inhibit this signal cascade could be a new class of antihypertensive drugs. Since the binding of WNK to OSR1/SPAK kinases was postulated to be important for signal transduction, we sought to discover inhibitors of WNK/SPAK binding by screening chemical compounds that disrupt the binding. For this purpose, we developed a high-throughput screening method using fluorescent correlation spectroscopy. As a result of screening 17000 compounds, we discovered two novel compounds that reproducibly disrupted the binding of WNK to SPAK. Both compounds mediated dose-dependent inhibition of hypotonicity-induced activation of WNK, namely the phosphorylation of SPAK and its downstream transporters NKCC1 (Na/K/Cl cotransporter 1) and NCC (NaCl cotransporter) in cultured cell lines. The two compounds could be the promising seeds of new types of antihypertensive drugs, and the method that we developed could be applied as a general screening method to identify compounds that disrupt the binding of two molecules.

N-Ethylmaleimide increases KCC2 cotransporter activity by modulating transporter phosphorylation

K⁺/Cl⁻ cotransporter 2 (KCC2) is selectively expressed in the adult nervous system and allows neurons to maintain low intracellular Cl⁻ levels. Thus, KCC2 activity is an essential prerequisite for fast hyperpolarizing synaptic inhibition mediated by type A γ-aminobutyric acid (GABA_A) receptors, which are Cl⁻-permeable, ligand-gated ion channels. Consistent with this, deficits in the activity of KCC2 lead to epilepsy and are also implicated in neurodevelopmental disorders, neuropathic pain, and schizophrenia. Accordingly, there is significant interest in developing activators of KCC2 as therapeutic agents. To provide insights into the cellular processes that determine KCC2 activity, we have investigated the mechanism by which N-ethylmaleimide (NEM) enhances transporter activity using a combination of biochemical and electrophysiological approaches. Our results revealed that, within 15 min, NEM increased cell surface levels of KCC2 and modulated the phosphorylation of key regulatory residues within the large cytoplasmic domain of KCC2 in neurons. More specifically, NEM increased the phosphorylation of serine 940 (Ser-940), whereas it decreased phosphorylation of threonine 1007 (Thr-1007). NEM also reduced with no lysine (WNK) kinase phosphorylation of Ste20-related proline/alanine-rich kinase (SPAK), a kinase that directly phosphorylates KCC2 at residue Thr-1007. Mutational analysis revealed that Thr-1007 dephosphorylation mediated the effects of NEM on KCC2 activity. Collectively, our results suggest that compounds that either increase the surface stability of KCC2 or reduce Thr-1007 phosphorylation may be of use as enhancers of KCC2 activity.

                                                                  

Tiagabine (trade name Gabitril) is n anticonvulsant medication produced by Cephalon that is used in the treatment of epilepsy. The drug is also used off-label in the treatment of anxiety disorders and panic disorder.

Tiagabine is approved by U.S. Food and Drug Administration (FDA) as an adjunctive treatment for partial seizures in individuals of age 12 and up. It may also be prescribed off-label by physicians to treat anxiety disorders and panic disorder as well as neuropathic pain (including fibromyalgia). For anxiety and neuropathic pain, tiagabine is used primarily to augment other treatments. Tiagabine may be used alongside selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, or benzodiazepines for anxiety, or antidepressants, gabapentin, other anticonvulsants, or opioids for neuropathic pain.^[4]

Tiagabine increases the level of γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system, by blocking the GABA transporter 1 (GAT-1), and hence is classified as a GABA reuptake inhibitor (GRI).

Conclusion

Today’s post shows how you need to read well beyond the autism research, not to miss something useful.

Some of today’s suggested therapies for Huntington’s are likely to help some types of autism, but some will certainly have a negative effect in some people.  For example, increasing the amount of GABA in the CNS would do my son no good at all.

The emerging field of drugs that enhance KCC2 should be very beneficial to all those with autism who are bumetanide responders.

Enhancing CKB with creatine is interesting. Creatine is a muscle building supplement used by body builders and some DAN doctors. It does have interactions at high doses.