Autophagy induction on impaired spermatogenesis of xeroderma pigmentosum group A gene-deficient mice.

Xeroderma pigmentosum (XP) involves a defect in the initial step of nucleotide excision repair (NER) and consists of eight genetic complementation groups (groups A-G and a variant). XP group A (XPA) patients have a high incidence of UV-induced skin tumors, immature testicular development, and neurological symptoms. In an earlier study, we have shown that XP group A (Xpa) gene-knockout mice (Xpa-/- mice) were highly sensitive to UV-induced skin carcinogenesis with a defect in NER and were highly susceptibility to spontaneous tumorigenesis with impaired spermatogenesis. However, the pathology of impaired spermatogenesis in Xpa-/- mice is unknown. To unravel the underlying pathology, we made a concerted effort using the testis of 3-month-old Xpa-/- mice. We found many large vacuoles in the seminiferous tubules of 3-month old Xpa-/- mice, while there were no large vacuoles in that of Xpa+/+ mice. Immunohistochemistry of microtubule-associated protein 1 light chain 3 (LC3), an autophagosome marker, showed degenerating cells with intense signal of LC3 in the seminiferous tubules, and immunoblotting revealed induction of LC3-II in the 3-month-old Xpa-/- mice. The results of the present study suggest autophagy induction as the possible mechanism underlying the impaired spermatogenesis in Xpa-/- mice. Therefore, Xpa-/- mice could be a useful model for investigating aging and male infertility with low expression of XPA.