Association of hMSH5 C85T polymorphism with radiation sensitivity of testicular cell lines GC-1, GC-2, TM3, and TM4

Background: The hMSH5 C85T polymorphism, which encodes hMSH5 P29S, is associated with individual differences in spermatogenic abnormalities caused by ionizing radiation (IR), but the molecular mechanisms remain unclear.

Objectives: This manuscript aims to explore the role of hMSH5 C85T polymorphism in IR-induced individual differences in spermatogenic abnormalities.

Material and methods: We transfected pcDNA-hMSH5^P29S vector into mouse spermatogonia GC-1, mouse spermatocytes GC-2, mouse testicular mesenchymal cells TM3, and mouse testicular support cells TM4. After radiation, we evaluated cell survival with colony formation assay, apoptosis with TUNEL assay and caspase-3 activity assay, DNA damage with comet assay and an in vivo NHEJ activity assay.

Results: Results showed that only spermatocytes GC-2 transfected with pcDNA-hMSH5^P29S vector had significant differences in IR-induced cell survival and apoptosis when compared to that transfected with pcDNA empty vector and pcDNA-wild-hMSH5 vector, while there was no statistical difference in GC-1, TM3, and TM4. In addition, comet assay showed that the DNA damage of GC-2 transfected with pcDNA-hMSH5^P29S vector increased significantly compared to that transfected with pcDNA empty vector and pcDNA-wild-hMSH5 vector after IR. And in vivo NHEJ activity assay showed that the NHEJ activity of GC-2 transfected with pcDNA-hMSH5^P29S vector was statistically higher than that transfected with pcDNA empty vector and pcDNA-wild-hMSH5 vector.

Conclusion: Our study indicates that the hMSH5 C85T polymorphism leads to an abnormal increase in apoptosis and lessen the control on error-prone NHEJ of spermatocyte GC-2, thereby altering the difference of radiation sensitivity of spermatogenesis.