Xiuli Zhang1, Tingwen Guan2, Boxuan Yang2, Zhihong Chi3, Zhan-You Wang4, Harvest F Gu5. 1. Department of Nephrology, The second People's Hospital, Shenzhen, The first Affiliated Hospital of Shenzhen University, Guangdong 518000, PR China; Department of Pathophysiology, China Medical University, Shenyang, Liaoning 110001, PR China. 2. Department of Pathophysiology, China Medical University, Shenyang, Liaoning 110001, PR China. 3. Department of Pathophysiology, China Medical University, Shenyang, Liaoning 110001, PR China. Electronic address: zhchi@cmu.edu.cn. 4. College of Life and Health Sciences, China Medical University, Shenyang, Liaoning 110001, PR China. 5. School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, PR China. Electronic address: feng.gu@cpu.edu.cn.
Abstract
OBJECTIVE: Zinc is intimately involved in testosterone production. Zinc transporter 8 (ZnT8) is found to be localized in insulin secretory granules as a β-cell specific Zn transporter. The effect of ZnT8 and related zinc accumulation in steroidogenesis, however, is still unknown. The present study aimed to explore whether ZnT8 plays a role in the facilitation of zinc accumulation and regulation of testosterone synthesis in testicles. METHODS: Leydig cells were isolated from the testicles of human, CD-1 suckling and ZnT8-KO mice. Zn accumulation in mitochondria was induced by hCG stimulation. Transfection of hZnT8-EGFP and RNA interfere of mZnT8 were done in MLTC-1 cells. ZnT8 expression and its co-localization with steroidogenic acute regulatory (StAR) protein were analyzed with RT-PCR, Western blot and dual-fluorescent staining protocols. Serum testosterone levels in mice were determined with chemiluminescent enzyme immunoassay. RESULTS: ZnT8 was found to be presented in Leydig cells and up-regulated in suckling mouse Leydig cells and MLTC-1 cells after hCG administration, by which zinc accumulation occurred in mitochondria. ZnT8 gene silencing or knockout inhibited stimulated progesterone and testosterone production, reduced stimulated zinc accumulation and down-regulated phosphorylated steroidogenic acute regulatory (StAR) expression in Leydig cells. Furthermore, an inhibitor (H89) of PKA blocked hCG-stimulated progesterone caused by ZnT8 over-expression and zinc treatment. CONCLUSION: The present study provided the first evidence that ZnT8 transports Zn into Leydig cell mitochondria with gonadotropin stimulation and suggests that ZnT8 may play a role in testosterone production via the PKA signaling pathway.
OBJECTIVE: Zinc is intimately involved in testosterone production. Zinc transporter 8 (ZnT8) is found to be localized in insulin secretory granules as a β-cell specific Zn transporter. The effect of ZnT8 and related zinc accumulation in steroidogenesis, however, is still unknown. The present study aimed to explore whether ZnT8 plays a role in the facilitation of zinc accumulation and regulation of testosterone synthesis in testicles. METHODS: Leydig cells were isolated from the testicles of human, CD-1 suckling and ZnT8-KO mice. Zn accumulation in mitochondria was induced by hCG stimulation. Transfection of hZnT8-EGFP and RNA interfere of mZnT8 were done in MLTC-1 cells. ZnT8 expression and its co-localization with steroidogenic acute regulatory (StAR) protein were analyzed with RT-PCR, Western blot and dual-fluorescent staining protocols. Serum testosterone levels in mice were determined with chemiluminescent enzyme immunoassay. RESULTS:ZnT8 was found to be presented in Leydig cells and up-regulated in suckling mouse Leydig cells and MLTC-1 cells after hCG administration, by which zinc accumulation occurred in mitochondria. ZnT8 gene silencing or knockout inhibited stimulated progesterone and testosterone production, reduced stimulated zinc accumulation and down-regulated phosphorylated steroidogenic acute regulatory (StAR) expression in Leydig cells. Furthermore, an inhibitor (H89) of PKA blocked hCG-stimulated progesterone caused by ZnT8 over-expression and zinc treatment. CONCLUSION: The present study provided the first evidence that ZnT8 transports Zn into Leydig cell mitochondria with gonadotropin stimulation and suggests that ZnT8 may play a role in testosterone production via the PKA signaling pathway.
Authors: Kristen E Syring; Karin J Bosma; Slavina B Goleva; Kritika Singh; James K Oeser; Christopher A Lopez; Eric P Skaar; Owen P McGuinness; Lea K Davis; David R Powell; Richard M O'Brien Journal: J Endocrinol Date: 2020-08 Impact factor: 4.286