Session: OR22-Male Reproductive Hormones: Effects on Fertility and Beyond
Room 104 (Moscone Center)
METHODS: We examined the global DNA methylation status of NOA men (n=26; n=5 controls) using the Infinium HumanMethylation450 BeadChip to identify DNA methylation abnormalities. Changes in the methylation status of MSH5 lead to further examination of a cohort of 371 NOA men and 66 fertile controls for specific mutations in the MSH5 gene by denatured high performance chromatography. The functional effects of MMR defects were tested by examining cellular growth in the presence and absence of MMC (mitomycin C) and MNU (N-Nitroso-N-mehylurea). MSH5 expression and localization was examined using qPCR, immunocytochemistry and western blots.
RESULTS: Analysis of DNA methylation identified significantly aberrant DNA methylation within MSH5 in 4 of 26 NOA men. The key regions of the MSH5 gene that encompass important functional domains of the protein, exon 2 and 15, revealed polymorphisms and genetic aberrations. A variant (C85T) that altered codon 29 of the MSH5 gene was identified. This resulted in a proline to serine change (P29S) in 11 infertile men and threonine 418 to alanine in 3 NOA men in exon 15. Testicular fibroblasts from 30 NOA men were resistant to the DNA alkylating agents MMC/MNU suggesting a functionally defective DNA MMR pathway. Fibroblasts from control men (n=10) exhibited sensitivity and did not proliferate. Immunocytochemisty, qPCR and western blots identified significantly decreased levels of MSH5 and cellular mislocalization in NOA men.
CONCLUSIONS: The DNA MMR pathway in NOA men exhibits defects in MSH5. These alterations may affect genetic stability and DNA recombination leading to impaired spermatogenesis.
Nothing to Disclose: ADR, JK, SM, JA, LLL, DJL
*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm
See more of: Abstracts - Orals, Featured Poster Presentations, and Posters