Endogenously produced LG3/4/5-peptide protects testes against toxicant-induced injury

Linxi Li,Lixiu Lv,C. Yan Cheng,Renshan Ge,Baiping Mao,Huitao Li,Siwen Wu

doi:10.1038/s41419-020-2608-8

Abstract

Laminin-α2 chain is one of the major constituent proteins of the basement membrane in the mammalian testis. The laminin-type globular (LG) domains of LG3, 4 and 5 (LG3/4/5, an 80 kDa fragment) can be cleaved from laminin-α2 chain at the C-terminus via the action of matrix metalloproteinase 9 (MMP-9). This LG3/4/5 is a biologically active fragment, capable of modulating the Sertoli cell blood–testis barrier (BTB) function by tightening the barrier both in vitro and in vivo. Overexpression of LG3/4/5 cloned into a mammalian expression vector pCI-neo in Sertoli cells in a Sertoli cell in vitro model with a functional BTB also protected Sertoli cells from cadmium chloride (CdCl2, an environmental toxicant) mediated cell injury. Importantly, overexpression of LG3/4/5 in the testis in vivo was found to block or rescue cadmium-induced BTB disruption and testis injury. LG3/4/5 was found to exert its BTB and spermatogenesis promoting effects through corrective spatiotemporal expression of actin- and MT-based regulatory proteins by maintaining the cytoskeletons in the testis, illustrating the therapeutic implication of this novel bioactive fragment.

Highlights

Recent studies have shown that laminin-α2 chain, one of the major constituent proteins of the basement membrane in the testis[1,2,3,4], can be cleaved by matrix metalloproteinase 9 (MMP-9) to generate a biologically active 80 kDa fragment[5]
Designated the apical ES-blood–testis barrier (BTB) axis wherein a locally produced F5-peptide generated from the laminin-γ3 chain, which serves as another autocrine peptide that promotes BTB disruption, making the barrier “leaky”[12,13,14,15]
Representation data of an experiment with triplicate bicameral units, and a total of n = 3 experiments that yielded similar results. *P < 0.05; **P < 0.01; Student’s t-test compared between corresponding treatment and pCI-neo control groups. e Overexpression of LG5 and LG3/4/5 was confirmed by RT-PCR for the experiment noted in f to examine their promoting effects on Sertoli cell epithelium to protect Sertoli cells from cadmium-mediated cell injury regarding disruptive changes on tight junction (TJ) (e.g., CAR, ZO-1) and basal ES (N-cadherin, ß-catenin) protein distribution at the Sertoli cell-cell interface

Summary

Introduction

Recent studies have shown that laminin-α2 chain (formerly called merosin), one of the major constituent proteins of the basement membrane in the testis[1,2,3,4], can be cleaved by matrix metalloproteinase 9 (MMP-9) to generate a biologically active 80 kDa fragment[5] This lamininα[2 80] kDa fragment containing the LG3/4/5 domain, generated at the basement membrane from laminin-α2 chain, was found to be transported to the apical ES, a testis-specific anchoring junction that confers spermatid adhesion to Sertoli cells in the seminiferous epithelium[6,7], through a microtubule (MT)-dependent transport mechanism[5]. This 80 kDa fragment is a novel regulatory peptide in the apical ES-

Methods

Results

Conclusion