Serine

From MyWiki
Jump to: navigation, search

Serine in ALS[edit]

Familial amyotrophic lateral sclerosis is associated with a mutation in D-amino acid oxidase (14.52 cM region on chromosome 12q22-23 linked to disease). D-amino acid oxidase gene (R199W DAO) controls the level of D-serine, which accumulates in the spinal cord in cases of sporadic ALS and in a mouse model of ALS, indicating that this abnormality may represent a fundamental component of ALS pathogenesis.[1]

To better understand the distribution of d-serine in ALS, researchers determined the activity and the expression of serine transporter in a motor neuronal cell line model of ALS (NSC-34/hSOD1G93A cells). Data suggest that the pathological alteration of d- and l-serine uptakes in ALS is driven by the affinity change of d-and l-serine uptake system.[2]

"The ALSFRS-R in the l-serine-treated patients showed a dose-related decrease in the rate of progression (34% reduction in slope, P = 0.044). The non-random distribution of addresses of ALS patients suggests that residential exposure to environmental pollutants may play an important role in the etiology of ALS. l-Serine in doses up to 15 g twice daily appears to be safe in patients with ALS. Exploratory studies of efficacy suggested that l-serine might slow disease progression. A phase II trial is planned." Source

ALSUntangled conclusion[edit]

"L-serine is a reasonably inexpensive, widely available nutritional supplement that has a plausible mechanism by which it could help a subset of patients who might have ALS from BMAA-toxicity. A small Phase I trial showed that L-serine up to 15 g twice daily is relatively well tolerated. A larger follow up trial is planned and will shed further light on its safety and utility as an ALS therapeutic. Unfortunately, since it is challenging to reliably measure BMAA in PALS, it will be difficult to identify the subset most likely to respond. Until a reliable assay for measuring BMAA exposure in living people arises, or a follow up trial confirms safety and demonstrates benefit independent of this, we cannot recommend L-serine as a treatment for ALS."

NOTE: ALSUntangled conclusion was written before the article Studies of Environmental Risk Factors in Amyotrophic Lateral Sclerosis (ALS) and a Phase I Clinical Trial of l-Serine was published.

References[edit]

  1. Mitchell et al.: Familial amyotrophic lateral sclerosis is associated with a mutation in D-amino acid oxidase. Proc. Natl. Acad. Sci. U.S.A. 2010;107:7556-61. PMID: 20368421. DOI. We report a unique mutation in the D-amino acid oxidase gene (R199W DAO) associated with classical adult onset familial amyotrophic lateral sclerosis (FALS) in a three generational FALS kindred, after candidate gene screening in a 14.52 cM region on chromosome 12q22-23 linked to disease. Neuronal cell lines expressing R199W DAO showed decreased viability and increased ubiquitinated aggregates compared with cells expressing the wild-type protein. Similarly, lentiviral-mediated expression of R199W DAO in primary motor neuron cultures caused increased TUNEL labeling. This effect was also observed when motor neurons were cocultured on transduced astrocytes expressing R199W, indicating that the motor neuron cell death induced by this mutation is mediated by both cell autonomous and noncell autonomous processes. DAO controls the level of D-serine, which accumulates in the spinal cord in cases of sporadic ALS and in a mouse model of ALS, indicating that this abnormality may represent a fundamental component of ALS pathogenesis.
  2. Lee et al.: The alteration of serine transporter activity in a cell line model of amyotrophic lateral sclerosis (ALS). Biochem. Biophys. Res. Commun. 2017;483:135-141. PMID: 28043791. DOI. The alteration of d-serine levels is associated with the pathogenesis of sporadic ALS and mutant SOD1 (G93A) animal model of ALS. However, the exact mechanism of d-serine transport is not known in ALS. To better understand the distribution of d-serine in ALS, we determined the activity and the expression of serine transporter in a motor neuronal cell line model of ALS (NSC-34/hSOD1(G93A) cells). The uptake of [(3)H]d-serine was significantly lower in NSC-34/hSOD1(G93A) cells than in control NSC-34 and NSC-34/hSOD1(wt) cells. In contrast, the uptake of [(3)H]l-serine, precursor of d-serine, was markedly increased in NSC-34/hSOD1(G93A) cells compared to control NSC-34 and NSC-34/hSOD1(wt) cells. Both [(3)H]d-serine and [(3)H]l-serine uptake were saturable in these cells. The estimated Michaelis-Menten constant, Km, for d-serine uptakes was higher in NSC-34/hSOD1(G93A) cells than in NSC-34/hSOD1(wt) cells while the Km for l-serine uptake was 2 fold lower in NSC-34/hSOD1(G93A) cells than in control cells. [(3)H]d-serine and [(3)H]l-serine uptakes took place in a Na(+)-dependent manner, and both uptakes were significantly inhibited by system ASC (alanine-serine-cysteine) substrates. As a result of small interfering RNA experiments, we found that ASCT2 (SLC1A5) and ASCT1 (SLC1A4) are involved in [(3)H]d-serine and [(3)H]l-serine uptake in NSC-34/hSOD1(G93A) cells, respectively. The level of SLC1A4 mRNA was significantly increased in NSC-34/hSOD1(G93A) compared to NSC-34 and NSC-34/hSOD1(wt) cells. In contrast, the level of SLC7A10 mRNA was relatively lower in NSC-34/hSOD1(G93A) cells than the control cells. Together, these data suggest that the pathological alteration of d- and l-serine uptakes in ALS is driven by the affinity change of d-and l-serine uptake system.