Deficient spermiogenesis in mice lacking Rlim

Abstract

The 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. 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 results in 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.

Identification of Selection Signals on the X-Chromosome in East Adriatic Sheep: A New Complementary Approach

“…RLIM (Ring Finger Protein, LIM domain interacting) was associated with ligase activity and transcriptional corepressor activity. It has also been linked to mouse lung development ( Kammoun et al, 2018 ) and spermiogenesis ( Wang et al, 2021 ). KIAA 2022 (Neurite Extension And Migration Factor) has been linked to nervous system development, while ABCB7 (ATP Binding Cassette Subfamily B Member 7) is involved in the transport of heme from mitochondria to the cytosol and has therefore been linked to mitochondrial iron accumulation.…”

ARRDC5 expression is conserved in mammalian testes and required for normal sperm morphogenesis

“…In mice that are homozygous for a null allele encoding the RING-type E3 ligase RNF8, spermatogenesis is defective with several impairments that reflect OAT, including reduced sperm count and high percentages of immotile and morphologically abnormal sperm 36 . In addition, although male mice that are knockout for the RING-type E3 ligase RLIM (also known as RNF12) are fertile, conditional inactivation of the gene in germ cells results in a reduction of sperm numbers, motility, and fertilization capacity 37 . Beyond spermatogenesis, expression of both RNF8 and RLIM occurs in an array of tissues and cell types where the molecules have important biological roles.…”

Knockout of Rlim Results in a Sex Ratio Shift toward Males but Superovulation Cannot Compensate for the Reduced Litter Size

“…However, the Cre transgene causes toxic effects on the male host animals by inducing genomic DNA recombination between two pseudo loxP sites, which have been found in the mammalian genome [ 23 , 24 , 25 , 26 ]. Moreover, the mutated maternal Rlim gene reduces the number and motility of sperm in adult male mice [ 20 ]. Hence, inactivating the loxP -flanked maternal Rlim gene with an autosome-linked Cre transgene in female embryos will cause toxicity and subfertility problems to their brothers.…”

“…Rlim is necessary for the normal development of female embryos, which express a relatively high level of Rlim during early embryonic stages ( Figure 1 ). Deletion of the maternal Rlim allele in male mice and mutation of the paternal Rlim allele in female mice have no significant effect on their growth and fertility [ 20 , 21 ]. However, knockout of the maternal Rlim allele results in abnormal imprinted XCI in extraembryonic trophoblasts, which causes defective development of placentas and the death of female embryos in utero [ 18 ].…”