Levels of Leydig cell autophagy regulate the fertility of male naked mole-rats

// Wenjing Yang 1, * , Li Li 2, * , Xiaofeng Huang 3, * , Guanghan Kan 4, * , Lifang Lin 1, * , Jishuai Cheng 1 , Chen Xu 1 , Wei Sun 1 , Wei Cong 1 , Shanmin Zhao 1 and Shufang Cui 1 1 Laboratory Animal Center, Second Military Medical University, Shanghai, China 2 Department of Training, Second Military Medical University, Shanghai, China 3 Medical Record Department, Ministry of Information, Changzheng Hospital, Second Military Medical University, Shanghai, China 4 China Astronaut Research and Training Center, Beijing, China * These authors contributed equally to this work Correspondence to: Shufang Cui, email: [email protected] Keywords: naked mole-rats, autophagy(definition), leydig cells, testis, nonbreeding Abbreviations: NMR: naked mole-rat; SEM: standard error of the mean; CCD: charge-coupled device; PS: primary spermatocytes; SS: secondary spermatocytes Received: December 08, 2016      Accepted: September 03, 2017      Published: October 26, 2017 ABSTRACT Fertility is abolished in nonbreeding males in colonies of natal naked mole-rats (NMRs). Although spermatogenesis occurs in both breeding and nonbreeding male NMRs, the mechanisms underlying the differences in fertility between breeders and nonbreeders remain unexplored. In this study, a significant decrease in autophagy was observed in Leydig cells of the testis from nonbreeding male NMRs. This alteration was visualised as a significant decrease in the levels of autophagy-related gene 7 (Atg7), Atg5, microtubule-associated protein 1A/B light chain 3 (LC3-II/I) and the number of autophagosomes and an increase in P62 levels using Western blotting analyses. Furthermore, monodansylcadaverine (MDC) staining and Western blot analyses revealed that testosterone production decreased in nonbreeding male NMR Leydig cells, this decrease was associated with a reduction in autophagy. Primary Leydig cells from breeding and nonbreeding male NMRs were processed to investigate the effect of an autophagy inhibitor (3-MA, 3-methyladenine) or an autophagy activator (mTOR(definition)-inhibiting drug studied for extending healthspan and lifespan." style="text-decoration:underline dotted; text-underline-offset:2px; cursor:help;">rapamycin(definition)) on testosterone production. Rapamycin induced an increase in testosterone production in NMR Leydig cells, whereas 3-MA had the opposite effect. Consequently, spermatogenesis, the weight of the testis, and androgen levels were dramatically reduced in nonbreeding male NMRs. While rapamycin treatment restored the fertility of nonbreeding male NMRs. Based on these results, inadequate autophagy correlates with a decrease in steroid production in nonbreeding male NMR Leydig cells, which may ultimately influence the spermatogenesis and fertilities of these animals.