Comparative Analysis on Methylation Levels of Nerve and Stress Related Genes in Charcot-Marie-Tooth Disease Type 1A Patients

Background@#Charcot-Marie-Tooth disease type 1A (CMT1A) is caused by duplication of the 17p12 region including PMP22 gene. In CMT1A patients, anticipation showing increased severity by generations has been reported in the CMT1A patients. It has also been reported that severity increases in the non-de novo cases than in the de novo cases. This study was performed to examine epigenetic differences between CMT1A cases and controls as well as between de novo cases and non-de novo cases. @*Methods@#This study examined 40 Korean CMT1A patients and 11 controls. Methylation level was determined using the SureSelect XT Methyl-Seq reagent kit and bisulfite sequence mapping program. @*Results@#Many differentially methylated CpG sites (DMCs) were identified in the comparisonbetween cases and controls and between de novo cases and non-de novo cases. Most DMCs were located within or nearby genes related to the nervous system, mental stress, and motor ability. @*Conclusions@#This study is the first epigenetic study to uncover the mechanism of clinical heterogeneity among CMT1A patients. We suggest that weak severity in the de novo cases than the non-de novo cases may be related to the epigenomic differences in the nerve and stress-related genes.

Peripheral Neuropathy and Decreased Locomotion of a RAB40B Mutation in Human and Model Animals

Rab40 proteins are an atypical subgroup of Rab GTPases containing a unique suppressor of the cytokine signaling (SOCS) domain that is recruited to assemble the CRL5 E3 ligase complex for proteolytic regulation in various biological processes. A nonsense mutation deleting the C-terminal SOCS box in the RAB40B gene was identified in a family with axonal peripheral neuropathy (Charcot-Marie-Tooth disease type 2), and pathogenicity of the mutation was assessed in model organisms of zebrafish and Drosophila. Compared to control fish, zebrafish larvae transformed by the human mutant hRAB40B-Y83X showed a defective swimming pattern of stalling with restricted localization and slower motility. We were consistently able to observe reduced labeling of synaptic markers along neuromuscular junctions of the transformed larvae. In addition to the neurodevelopmental phenotypes, compared to normal hRAB40B expression, we further examined ectopic expression of hRAB40B-Y83X in Drosophila to show a progressive decline of locomotion ability. Decreased ability of locomotion by ubiquitous expression of the human mutation was reproduced not with GAL4 drivers for neuron-specific expression but only when a pan-glial GAL4 driver was applied. Using the ectopic expression model of Drosophila, we identified a genetic interaction in which Cul5 down regulation exacerbated the defective motor performance, showing a consistent loss of SOCS box of the pathogenic RAB40B. Taken together, we could assess the possible gain-of-function of the human RAB40B mutation by comparing behavioral phenotypes in animal models; our results suggest that the mutant phenotypes may be associated with CRL5-mediated proteolytic regulation.

Pycnogenol attenuates the symptoms of immune dysfunction through restoring a cellular antioxidant status in low micronutrient-induced immune deficient mice

BACKGROUND/OBJECTIVES: We investigated the effect of Pycnogenol (Pyc) on survival and immune dysfunction of C57BL/6 mice induced by low micronutrient supplementation. MATERIALS/METHODS: Female C57/BL/6 mice were fed a diet containing 7.5% of the recommended amount of micronutrients for a period of 12 wks (immunological assay) and 18 wks (survival test). For immunological assay, lymphocyte proliferation, cytokine regulation, and hepatic oxidative status were determined. RESLUTS: Pyc supplementation with 50 and 100 mg.kg(-1).bw.d(-1) resulted in partial extension of the median survival time. Pyc supplementation led to increased T and B cell response against mitogens and recovery of an abnormal shift of cytokine pattern designated by the decreased secretion of Th1 cytokine and increased secretion of Th2 cytokine. Hepatic vitamin E level was significantly decreased by micronutrient deficiency, in accordance with increased hepatic lipid peroxidation level. However, Pyc supplementation resulted in a dose-dependent reduction of hepatic lipid peroxidation, which may result from restoration of hepatic vitamin E level. CONCLUSION: Findings of this study suggest that Pyc supplementation ameliorates premature death by restoring immune dysfunction, such as increasing lymphocyte proliferation and regulation of cytokine release from helper T cells, which may result from the antioxidative ability of Pyc.