| TEX101 is a testis-specific cell surface protein expressed exclusively in the male germ cells, and it was previously suggested as a biomarker for the differential diagnosis of male infertility. Molecular function of TEX101 is not known, but previous studies demonstrated that murine TEX101 was a cell membrane chaperone, essential for fertilization. In this work, we employed quantitative proteomic strategies to investigate the clinical and the functional aspects of human TEX101 protein.;To facilitate translation of TEX101 into clinic, we first developed and optimized an immunoassay for TEX101 measurement in biological fluids. We then evaluated the performance of TEX101 ELISA in 805 seminal plasma samples of fertile, sub-fertile, and infertile men. We demonstrated the clinical utility of TEX101 to evaluate vasectomy success, to stratify azoospermia forms and subtypes, and to predict the success of sperm retrieval in patients diagnosed with non-obstructive azoospermia.;To gain insights into human TEX101 function, we employed mass spectrometry approaches to investigate the physical and the transient TEX101 interactome. Co-immunoprecipitation-mass spectrometry revealed a testis-specific complex TEX101-DPEP3 which was validated by hybrid immunoassay in testicular tissues and spermatozoa. In addition, we discovered a TEX101 rs35033974 homozygous knockdown model, which carried a missense variation leading to near-complete protein degradation. We then performed global proteomic analysis of TEX101 knockdown spermatozoa, and we identified the transient interactome of TEX101.;New knowledge on TEX101 will provide insights into reproductive biology, facilitate better diagnostics of male infertility, contribute to rational selection of assisted reproduction treatments, and offer new protein targets to develop non-hormonal male contraceptives. |
