Vitamin D Treatment Reverses the Induced Oxidative Stress Damage to DNA

Environmental exposures associated with elevated risk for autism spectrum disorder may augment the burden of deleterious de novo mutations among probands

Although the full aetiology of autism spectrum disorder (ASD) is unknown, familial and twin studies demonstrate high heritability of 60-90%, indicating a predominant role of genetics in the development of the disorder. The genetic architecture of ASD consists of a complex array of rare and common variants of all classes of genetic variation usually acting additively to augment individual risk. The relative contribution of heredity in ASD persists despite selective pressures against the classic autistic phenotype; a phenomenon thought to be explained, in part, by the incidence of spontaneous (or de novo) mutations. Notably, environmental exposures attributed as salient risk factors for ASD may play a causal role in the emergence of deleterious de novo variations, with several ASD-associated agents having significant mutagenic potential. To explore this hypothesis, this review article assesses published epidemiological data with evidence derived from assays of mutagenicity, both in vivo and in vitro, to determine the likely role such agents may play in augmenting the genetic liability in ASD. Broadly, these exposures were observed to elicit genomic alterations through one or a combination of: (1) direct interaction with genetic material; (2) impaired DNA repair; or (3) oxidative DNA damage. However, the direct contribution of these factors to the ASD phenotype cannot be determined without further analysis. The development of comprehensive prospective birth cohorts in combination with genome sequencing is essential to forming a causal, mechanistic account of de novo mutations in ASD that links exposure, genotypic alterations, and phenotypic consequences.

Small Molecule Rescue of ATXN3 Toxicity in C. elegans via TFEB/HLH-30

Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), is a polyglutamine expansion disease arising from a trinucleotide CAG repeat expansion in exon 10 of the gene ATXN3. There are no effective pharmacological treatments for MJD, thus the identification of new pathogenic mechanisms, and the development of novel therapeutics is urgently needed. In this study, we performed a comprehensive, blind drug screen of 3942 compounds (many FDA approved) and identified small molecules that rescued the motor-deficient phenotype in transgenic ATXN3 Caenorhabditis elegans strain. Out of this screen, five lead compounds restoring motility, protecting against neurodegeneration, and increasing the lifespan in ATXN3-CAG89 mutant worms were identified. These compounds were alfacalcidol, chenodiol, cyclophosphamide, fenbufen, and sulfaphenazole. We then investigated how these molecules might exert their neuroprotective properties. We found that three of these compounds, chenodiol, fenbufen, and sulfaphenazole, act as modulators for TFEB/HLH-30, a key transcriptional regulator of the autophagy process, and require this gene for their neuroprotective activities. These genetic-chemical approaches, using genetic C. elegans models for MJD and the screening, are promising tools to understand the mechanisms and pathways causing neurodegeneration, leading to MJD. Positively acting compounds may be promising candidates for investigation in mammalian models of MJD and preclinical applications in the treatment of this disease.

Vitamin D receptor (VDR) gene polymorphism in Egyptian vitiligo patients

BACKGROUND

Vitiligo is an autoimmune dermatological disorder, precipitated by genetic and nongenetic factors leading to destruction of epidermal melanocytes. In Egypt, it has a prevalence rate of 1.2%. Vitamin D has stimulatory and protective effects on melanocytes and acts through its nuclear vitamin D receptor (VDR) on target cells. The consequences of polymorphisms in VDR have been previously studied for mapping their link with various disorders of autoimmune etiology.

AIM OF THIS WORK

To study Apa-I and Taq-I VDR single-nucleotide polymorphisms (SNPs) and the risk to develop vitiligo.

METHODS

Extracted genomic DNA from the venous blood of 60 patients and controls was amplified and analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for analysis of VDR gene polymorphisms. Serum 25-hydroxyvitamin D3 (25-OH-D3) level was measured using ELISA technique.

RESULTS

The most common VDR genotypes were AA and TT among both groups with no significant difference. Analysis of the frequency of combinations of genotypes revealed AATT as the most common among patients (36.7%) while in the control group, AATt is the most common (33.3%) but no significant difference was noted on comparison of both groups. The genotype allele tt appeared to be more expressed in patients with marginal significance value (P 0.053). Serum 25-OH-D3 showed a relatively decreased level among patients and controls with no statistically significant difference.

CONCLUSION

Although VDR SNPs are not correlated with vitiligo, the elevated frequency of tt genotype among vitiligo patients may suggest the risk to develop the disease.

Reductive Stress-Induced Mitochondrial Dysfunction and Cardiomyopathy

The goal of this review was to summarize reported studies focusing on cellular reductive stress-induced mitochondrial dysfunction, cardiomyopathy, dithiothreitol- (DTT-) induced reductive stress, and reductive stress-related free radical reactions published in the past five years. Reductive stress is considered to be a double-edged sword in terms of antioxidation and disease induction. As many underlying mechanisms are still unclear, further investigations are obviously warranted. Nonetheless, reductive stress is thought to be caused by elevated levels of cellular reducing power such as NADH, glutathione, and NADPH; and this area of research has attracted increasing attention lately. Albeit, we think there is a need to conduct further studies in identifying more indicators of the risk assessment and prevention of developing heart damage as well as exploring more targets for cardiomyopathy treatment. Hence, it is expected that further investigation of underlying mechanisms of reductive stress-induced mitochondrial dysfunction will provide novel insights into therapeutic approaches for ameliorating reductive stress-induced cardiomyopathy.