Deficient spermiogenesis in mice lackingRlim

Abstract

SummaryThe X-linked gene Rlim plays major roles in female mouse development and reproduction, where it is crucial for the maintenance of imprinted X chromosome inactivation in extraembryonic tissues of embryos. However, while females carrying a systemic Rlim knockout (KO) die around implantation, male Rlim KO mice appear healthy and are fertile, raising questions as to the pressures driving Rlim gene selection during evolution. Here we report an important role for Rlim in testis where it is highly expressed in post-meiotic round spermatids as well as in Sertoli cells. Systemic deletion of the Rlim gene leads to lower numbers of mature sperm that contains excess cytoplasm, leading to decreased sperm motility and in vitro fertilization rates. Targeting the conditional Rlim cKO specifically to the spermatogenic cell lineage largely recapitulates this phenotype. These results reveal functions of Rlim in male reproduction specifically in round spermatids during spermiogenesis with likely evolutionary implications.

A RNF12-USP26 amplification loop promotes germ cell specification and is disrupted in urogenital disorders

“…Our data shows that RNF12-mediated REX1 degradation controls expression of genes involved in germ cell priming, which complements the recent finding that RNF12/RLIM is required for spermiogenesis in mice (Wang et al, 2020a). We build on this important observation by defining the molecular mechanisms by which RNF12 regulates gametogenesis genes and find that USP26 and the closely related USP29 may also be involved in fertility by regulating RNF12.…”

An RNF12-USP26 amplification loop drives germ cell specification and is disrupted by disease-associated mutations

“…We next investigated the physiological function of the RNF12-USP26 signaling axis. RNF12 is required for normal sperm development ( 9 ), a process in which USP26 has also been implicated ( 24 – 28 ). Furthermore, USP26 variants have been associated with azoospermia in various fertility disorders, including Sertoli cell–only syndrome ( 24 , 25 , 37 ).…”

“…USP26 protein expression was analyzed by 3,3′-diaminobenzidine tetrahydrochloride (DAB) immunohistochemistry of mouse testes sections prepared from two biological replicates of 8-week-old Rlim fl/y and Rlim −/y littermates ( 15 ) using USP26 antibody (1:100 dilution; table S2). These experiments were performed as described previously ( 9 ).…”

“…RNF12 has been shown to ubiquitylate the transcriptional regulators SMAD7 (11), REX1 (12), and CLIM (13), among others. As a result, RNF12 plays a key role in coordinating developmental gene expression, with functions including gene dosage compensation by imprinted X-chromosome inactivation (XCI) (14)(15)(16) and transcriptional repression of neurodevelopmental genes (17). However, beyond these notable examples, RNF12 regulation and function have not been systematically investigated at the molecular level, which may shed light on further key developmental functions that are disrupted in disease.…”

Coding and regulatory transcriptome comparisons between fertile and infertile spermatozoa identify RNA signatures of male infertility

“…Paip2b knockout mice have defective elongated spermatids and the translation of many essential proteins was inhibited in late spermatogenesis (Yanagiya et al, 2010). Similarly, Rlim is highly expressed in post-meiotic round spermatids and Sertoli cells, the lack of which results in decreased sperm count, decreased sperm motility and in vitro fertilization rates (Wang et al, 2021). Among others, UBR2 is an ubiquitin ligase involved in histone ubiquitination, the lack of which causes infertility with meiotic arrest (An et al, 2010).…”