Determination of expression and function of small-VPC-interacting protein (SVIP) in mouse testis

Small VCP-Interacting Protein (SVIP) is a 9-kDa protein that is composed of 76 amino acids of the family of Endoplasmic Reticulum-Associated Protein Degradation (ERAD). Recent studies have shown that SVIP is a androgen-responsive protein and SVIP expression is regulated by androgens. Until now, however, the cellular localization and possible function of SVIP in tissue, where the androgen receptors is overexpressed, have not been investigated. Therefore we aimed to detect the protein expression of SVIP at the cellular level and the possible function of SVIP in mouse testis by cell culture studies. In developing mouse testes, fetal (18 and 19 days, n: 6), postnatal (1, 5, 15, 35 days, n: 6) and adult mice (50 days, n: 6) were used to determine protein expression of SVIP. The obtained testis tissues were used for Immunohistochemistry and Western blot studies. In addition, TM3 and MA-10 mouse Leydig cells were cultured, and the expression of SVIP and the steroidogenic acute regulator protein (STAR) were evaluated by fluorescence microscopy with colocalization studies. The expressional changes of STAR was studied by using SVIP siRNA's in Leydig cell cultures. In this study, the expression of the SVIP protein, was demonstrated by Immunohistochemistry and Western blot studies. The expression of SVIP protein was increased in developing testicular tissues. In fetal, postnatal and adult mice testes SVIP expression was predominantly observed in Leydig cells. SVIP expression was also detected in TM3 and MA-10 Leydig cells and the correlation between SVIP expression and steroidogenezis was established. Suppression of SVIP resulted in the diminished expression of STAR which is a Leydig cell marker. The expression of two proteins were positively correlated in Leydig cell. Key words: SVIP, STAR, Mouse Testis, Leydig Cell.