The role of hepatitis B virus surface protein in inducing Sertoli cell ferroptosis

Abstract

Backgrounds: Hepatitis B virus infection could result in male infertility with sperm defects and dysfunction. Sertoli cells are essential for testis function and play a crucial role in spermatogenesis. Sertoli cell death contributes to spermatogenesis impairment, leading to poor sperm quality. Ferroptosis has been implicated as a mechanism of Sertoli cell death. The issue in studying the relationship between hepatitis B virus and Sertoli cell ferroptosis has not yet been addressed.

Objectives: To explore the mechanisms underlying ferroptosis in hepatitis B virus-exposed Sertoli cells.

Materials and methods: Human Sertoli cells were treated in vitro with levels of 25, 50, and 100 μg/mL of hepatitis B virus surface protein (HBs). Cell viability and levels of glutathione, malondialdehyde, cellular ferrous ion (Fe²⁺ ), lipid peroxidation, and N6-methyladenosine in Sertoli cells were detected. The level of glutathione peroxidase 4, transferrin receptor 1, ferritin heavy chain, tripartite motif (TRIM) 37, methyltransferase like 3, and insulin-like growth factor 2 mRNA binding protein 2 was examined. Cell transfection was carried out to alter expression of ferroptosis-related proteins. qPCR and immunoblotting were performed to measure protein expression level. Immunoprecipitation was applied to determine the protein and protein-RNA interaction. Luminescence analysis was performed to identify the target of methyltransferase like 3.

Results: HBs exposure triggered ferroptosis featured with increased intracellular Fe²⁺ ion, reduced cell viability and expression of glutathione peroxidase 4 in Sertoli cells. HBs treatment significantly increased TRIM37 expression, which suppressed glutathione peroxidase 4 expression through ubiquitination. TRIM37 silencing attenuated the effect of HBs exposure-regulated cell viability and ferroptosis. HBs upregulated N6-methyladenosine modification in TRIM37 3'-UTR by increasing methyltransferase like 3 expression. The binding of N6-methyladenosine reader insulin-like growth factor 2 mRNA binding protein 2 and TRIM37 3'-UTR enhanced the stability of TRIM37 mRNA.

Conclusion: HBs can decrease human Sertoli cell viability by promoting ferroptosis induced by the loss of glutathione peroxidase 4 activity through TRIM37-mediated ubiquitination of glutathione peroxidase 4. The findings highlight the role of TRIM37/glutathione peroxidase 4 signaling responsible for ferroptosis regulation in hepatitis B virus-infected Sertoli cells.

Keywords: Sertoli cell; TRIM37; ferroptosis; hepatitis B virus surface protein; ubiquitination.