Regulatory Effect of L-Cysteine on Testosterone Biosynthesis Genes in Leydig Cells and THP-1 Monocytes

Abstract

Background: Spermatogenesis involves a series of complicated cellular events resulting in the production of mature spermatids. Leydig cells of the testis are essential to forming a spermatozoon. Leydig cells are the interstitial cells that reside between seminiferous tubules and their key role is in the biosynthesis of testosterone. Leydig cells also regulate testicular macrophage and are stocked with innate defense systems. CYP11A1 is a major enzyme in the biosynthesis pathway of testosterone which converts the cholesterol to pregnenolone in the mitochondria of Leydig cells. L-Cysteine (L-Cys) acts as a precursor of glutathione, an antioxidant that plays a vital role against oxidative stress damage. Previous animal studies report the protective effect of L-Cys against chemical/radiation-induced-testicular damage. This study examined the biochemical mechanisms by which L-Cys stimulates testosterone biosynthesis and relative expression of blood-testis barrier (BTB) genes in Leydig cells and THP-1 monocytes. Methodology: The THP-1 monocytes and Leydig cells were treated with L-Cys for 24 hours. Following treatment, RNA was extracted, and the expression of the testosterone biosynthesis gene and BTB genes was analyzed using quantitative RT-PCR. Data (n=4) is presented as mean ± SEM and p-values ≤0.05 are considered as significant. Results: Expression of CLDN1 (p=0.006), CLDN11 (p=0.03), and TJP1 (p=0.04) genes was significantly higher in Leydig cells than in the THP-1 monocytes. There is no significant change in the expression of testosterone-regulatory genes between Leydig cells and THP-1 monocytes. In THP-1 monocytes, L-Cys treatment significantly upregulated the expression of CYP11A1 (p=0.03), CYP19A1 (p=0.002), and BTB genes: CLDN1 (p=0.05), CLDN2 (p=0.001), CLDN4 (p=0.0006), CLDN11 (p=0.006), and TJP1 (p=0.03). Similarly, L-Cys (500uM) treatment significantly upregulated (p=0.03) the CYP11A1 gene expression in HLC, further, the expression of BTB genes: CLDN1 (p=0.03), CLDN11 (p=0.02), and TJP1 (p=0.02) was also upregulated. Conclusion: This study shows that L-Cys increases the expression of testosterone-related genes in both HLC and THP-1. The expression profile of the BTB genes was higher in HLC than in THP-1 monocytes. L-Cys supplementation upregulates the expression of the testosterone biosynthesis pathway gene which can increase spermatogenesis and reduce the male infertility risk. Funding source: NIH/NCCIH (5R33AT010637) and the Malcolm Feist Endowed Chair in Diabetes. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.