V-Set and Immunoglobulin Domain-Containing 1 (VSIG1), Predominantly Expressed in Testicular Germ Cells, Is Dispensable for Spermatogenesis and Male Fertility in Mice.

Yena Jung,Sang-Rae Lee,Ekyune Kim,Chaeli Park,Dong-Won Seol,Sun-Uk Kim,Ji-Su Kim,Jeong-Woong Lee,Young-Hyun Kim,Young-Ho Park,Na-Eun Park,Bong-Seok Song,Hyewon Bang,Bo-Woong Sim,Sunhyung Kim,Gabbine Wee

doi:10.3390/ani11041037

Abstract

Simple SummaryV-set and immunoglobulin domain-containing 1 (VSIG1) is a newly discovered member of the junctional adhesion molecule (JAM) family encoded by a gene located on the X chromosome in humans and mice. Expression of VSIG1 in normal mammalian tissues was originally reported to be highly tissue-specific and was detected in organs such as the testis. However, as little is known about its physiological function, we aimed to investigate the function of VSIG1 in mammalian spermatogenesis and fertilization.To elucidate the functional role of V-set and immunoglobulin domain-containing 1 (VSIG1) in spermatogenesis and fertilization, we knocked out (KO) VSIG1 in a mouse embryo using CRISPR/Cas9 (Clustered regularly interspaced short palindromic repeat/CRISPR-associated protein 9) -mediated genome editing. Reverse transcription PCR was performed using cDNA synthesized from VSIG1 KO testis RNA. Although Western blot analysis using a specific antibody to VSIG1 confirmed VSIG1 protein defects in the KO mice, hematoxylin-eosin staining analysis was similar in the KO and wild-type mice. Additionally, computer-assisted sperm analysis and in vitro fertilization experiments were conducted to confirm the activity and fertilization ability of sperm derived from the KO mouse. Mice lacking VSIG1 were viable and had no serious developmental defects. As they got older, the KO mice showed slightly higher weight loss, male mice lacking VSIG1 had functional testes, including normal sperm number and motility, and both male and female mice lacking VSIG1 were fertile. Our results from VSIG1 KO mice suggest that VSIG1 may not play essential roles in spermatogenesis and normal testis development, function, and maintenance. VSIG1 in sperm is dispensable for spermatogenesis and male fertility in mice. As several genes are known to possess slightly different functions depending on the species, the importance and molecular mechanism of VSIG1 in tissues of other species needs further investigation.

Highlights

For fertilization to succeed in mammals, ejaculated sperm must enter the female reproductive organs where it meets an ovulated oocyte
An in vitro fertilization assay demonstrated no significant difference in the functions of epididymal sperm between wild-type and V-set and immunoglobulin domain-containing 1 (VSIG1) KO mice
The present study determined the function of VSIG1, a testicular germ cell surface transmembrane protein, using KO mice generated by means of clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) technology

Summary

Introduction

For fertilization to succeed in mammals, ejaculated sperm must enter the female reproductive organs where it meets an ovulated oocyte. It must digest the cumulus cell mass around the oocyte, bind to and infiltrate the zona pellucida, and bind/fuse to the plasma membrane of the oocyte [1,2,3,4]. Despite extensive research on the molecular causes of human infertility, the underlying mechanism remains unclear. Numerous studies have shown that both male and female factors contribute to human infertility [5,6,7]. Research has shown that male infertility is affected by several environmental, behavioral, and genetic factors [8]. Several studies have demonstrated that the interactions between the surface proteins of spermatogenic cells and Sertoli cells are important in spermatogenesis [8,9]

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