Identification of a damaging variant rs35033974 associated with idiopathic male infertility through degradation of TEX101 protein and its transient interactome

Human TEX101 is a testis-specific cell membrane protein expressed exclusively in male germ cells and a validated biomarker of male infertility. TEX101 was suggested to function as a cell surface chaperone of numerous proteins involved in sperm migration and sperm-egg interaction. However, the precise functional roles of human TEX101 in spermatogenesis and fertilization are unknown. Here, we show that a common homozygous variant rs35033974 of TEX101 (G99V) with ~1% frequency in the general population may be associated with idiopathic male infertility. Spermatozoa from patients with homozygous rs35033974 exhibited near-complete degradation of variant G99V TEX101 protein and concomitant degradation of its interactome, as revealed by proteomic measurements. Substantially reduced levels of numerous testis-specific membrane proteins involved in sperm migration and sperm-oocyte fusion (including LY6K, IZUMO3 and ADAM29) were confirmed in spermatozoa of men with homozygous G99V variant. These men were previously diagnosed with idiopathic male infertility or oligospermia and failed the treatment by intrauterine insemination. Collectively, these data may facilitate diagnostics of idiopathic male infertility, provides a rational for selection of male infertility treatments and validate TEX101 and its interactome as targets to develop non-hormonal male contraceptives.