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  • Effect of DCAF17 Disruption...
    Elmokayed, Heba Raafat

    01/2024
    Dissertation

    Male infertility has become a significant health issue over the past few decades, and various factors such as lifestyle choices, hormonal imbalances, and genetic abnormalities contribute to this condition. Genetic disorders are responsible for about 15% of cases of male infertility, impacting processes like sperm production and sperm quality. Spermatogenesis, the complex process of generating mature sperm, involves numerous molecular and cellular pathways. One such pathway is ubiquitination, which plays a vital role in normal sperm production by managing protein balance in the testes. Ubiquitination is a highly conserved, multistep enzymatic process of post-translational modification of target protein by covalent attachment of ubiquitin determine the stability and/or activity of the target proteins. Cullin‐RING E3 ligases (CRLs) are multi-subunit complexes comprise the largest family of RING‐based E3 ubiquitin ligases that catalyze final step of ubiquitination to transfer ubiquitin to target proteins. DDB1- and CUL4-associated factors (DCAFs) have been reported to serve as substrate receptors for the Cullin4‐RING E3 ligases (CRL4) complexes to recruit diverse proteins for ubiquitination and thus confer specificity to CRL4s. DCAF17 is a member of DCAF protein family and mutations in the gene encoding this protein cause a rare autosomal recessive genetic disorder known a Woodhouse-Sakati syndrome (WSS), which is characterized by hypogonadism, alopecia, diabetes mellitus and mental retardation. However, the role of DCAF17 is unknown. To investigate the role of DCAF17, a knockout mouse model for Dcaf17 gene was generated using gene targeting approach through Cre/LoxP strategy. Disruption of Dcaf17 in mice caused male infertility due to severe defects in spermatogenesis and testicular function. To further characterize the effect of Dcaf17 on spermatogenesis at cellular and molecular level, various cell and molecular biology techniques such as qRT-PCR, Western blotting and immunofluorescence imaging techniques were employed to evaluate the expression of different genes and proteins involved in ubiquitination, chromatin modification and chromatin remodeling. Our results showed that disruption of Dcaf17 can have complex effects on the expression of chromatin modification enzymes, remodeling factors, ubiquitination and genes involved in spermatogenesis, potentially contributing to disruptions in germ cell development and male fertility. Although the disruption of Dcaf17 altered the differential expression of chromatin modification enzymes and remodeling factors (Tnp2, Prm2, Tnp1, Prm1, Ube2e3, Suv39h1, Prmt8, Ube2a, Tnp1, Nsd1, Suv39h1, Mecp2, Cul4b and Prmt8), the translational levels of these proteins show comparable differences between WT and Dcaf17 KO. Findings of our research are novel and significant because they provide a basis for further studies to elucidate molecular mechanisms underlying the function of DCAF17 in ormal spermatogenesis and male fertility. It will also open a door to develop new possible diagnostic and, possibly, therapeutic tools for male infertility disorders.