Project description:Male factor infertility affects about 7% of men in the general population and it can be related to a number of different etiologic factors, including genetic anomalies. Both sex chromosomes are enriched in genes prevalently or exclusively expressed in the testis. Nevertheless only the Y chromosome-linked Copy Number Variants (CNVs) and Y-linked genes have been demonstrated as important contributors to impaired sperm production in humans Data on the potential role of X-linked gene products in spermatogenesis derives mainly from model organisms. X-linked genes seem to be expressed both in pre-meiotic and post-meiotic germ cells in the mouse testis and interestingly those expressed in the post-meiotic cells belong to multicopy gene families. The apparent paucity of X-linked factors in male infertility is most likely related to the scarcity of studies, which focused only on a total of seven genes. No pathogenic mutations causing infertility have, thus far, been described in these genes, with the exception of AR gene In order to advance in the understanding of the role of X-linked CNVs and genes in male infertility, we applied an innovative approach based on high resolution X chromosome specific CGH array. Given that such a detailed analysis of the X chromosome has not been published so far and the testicular function of subjects included in the Genomic Variant Database is unknown (except for 24 X-linked CNVs reported in the recent paper by Tuttelmann), our is the first study providing a detailed analysis of X-linked losses and gains in several hundreds of subjects with known sperm parameters.
Project description: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.