Functional role of the Sperm Associated Antigen 11a Spag11a gene in epididymal oncogenesis and fertility studies using transgenic models

Abstract

Epididymis is the site of sperm maturation during which the male gametes acquire newlinemotility and fertilizing ability. The lumen of this organ is lined by epithelial cells, which form newlinethe predominant cell type. A variety of proteins are secreted by the epithelial cells in a region newlinespecific manner and have been implicated in sperm function and innate immunity and as newlinemarkers of many types of cancers. The rat SPAG11A, an epididymis specific protein was newlineimplicated in sperm maturation and is antimicrobial in nature because of its structural newlinesimilarity with and#946;-defensins. Recent evidence indicates that and#946;-defensins play a role in tumor newlinegrowth, monitoring and treatment. Further, human and#946;-defensins are implicated in cervical, newlinethyroid, prostate, colon, oral and lung cancer carcinogenesis. However, the role of defensinlike newlineproteins belonging to the SPAG11 family in cell proliferation and their possible newlinecontribution to cancer is not yet reported. On the other hand, proteins encoded by Spag11 newlinegenes are found to be localized on the sperm, thus implicating them in sperm function as newlinewell. Studies that implicate a direct role for SPAG11A in sperm function and fecundity are newlinenot yet understood. newlineMethodology newlinePrimary epithelial cells of the caput (PEC) were isolated from rats as described earlier newlinewith slight modifications. The effect of depleting Spag11a mRNA on global gene expression newlinepattern was studied by treating EPECs with siRNA. The effect of overexpressing Spag11a in newlineRCE cells was analyzed by transfecting a Spag11a expression construct. Gene array analyses newlinewas carried out using Affymetrix GeneChip Scanner and GeneTitan Platform. newlineImmunization to generate auto antibodies against SPAG11A was carried out in adult newline(aged 90 days) male Wistar rats and the antibody titer in serum and tissue fluids was newlinedetermined by ELISA. The susceptibility of epididymis to tumorigenesis was determined by newlineadministering SPAG11A immunized rats with 0.01% diethynitrosamine (DEN) for 12 weeks. newlineTransgenic rats that express shRNA against Spag11a mRNA were generated