Deletion of the Spata3 Gene Induces Sperm Alterations and In Vitro Hypofertility in Mice

Thanks to the analysis of an Interspecific Recombinant Congenic Strain (IRCS), we previously defined the Mafq1 quantitative trait locus as an interval on mouse Chromosome 1 associated with male hypofertility and ultrastructural abnormalities. We identified the Spermatogenesis associated protein 3 gene (Spata3 or Tsarg1) as a pertinent candidate within the Mafq1 locus and performed the CRISPR-Cas9 mediated complete deletion of the gene to investigate its function. Male mice deleted for Spata3 were normally fertile in vivo but exhibited a drastic reduction of efficiency in in vitro fertilization assays. Mobility parameters were normal but ultrastructural analyses revealed acrosome defects and an overabundance of lipids droplets in cytoplasmic remnants. The deletion of the Spata3 gene reproduces therefore partially the phenotype of the hypofertile IRCS strain.

Association of FOXD1 variants with adverse pregnancy outcomes in mice and humans

Recurrent spontaneous abortion (RSA) is a common cause of infertility, but previous attempts at identifying RSA causative genes have been relatively unsuccessful. Such failure to describe RSA aetiological genes might be explained by the fact that reproductive phenotypes should be considered as quantitative traits resulting from the intricate interaction of numerous genetic, epigenetic and environmental factors. Here, we studied an interspecific recombinant congenic strain (IRCS) of Mus musculus from the C57BL6/J strain of mice harbouring an approximate 5 Mb DNA fragment from chromosome 13 from Mus spretus mice (66H-MMU13 strain), with a high rate of embryonic resorption (ER). Transcriptome analyses of endometrial and placental tissues from these mice showed a deregulation of many genes associated with the coagulation and inflammatory response pathways. Bioinformatics approaches led us to select Foxd1 as a candidate gene potentially related to ER and RSA. Sequencing analysis of Foxd1 in the 66H-MMU13 strain, and in 556 women affected by RSA and 271 controls revealed non-synonymous sequence variants. In vitro assays revealed that some led to perturbations in FOXD1 transactivation properties on promoters of genes having key roles during implantation/placentation, suggesting a role of this gene in mammalian implantation processes.

Use of recombinant congenic and congenic strains of NOD mice to identify a new insulin-dependent diabetes resistance gene.

Insulin-dependent diabetes mellitus (IDDM) in NOD/Lt mice represents a complex polygenic disease. NOR/Lt is a recombinant congenic strain (RCS) in which limited regions of the NOD/Lt genome have been replaced by genome from the C57BL/KsJ strain. NOR mice are insulitis resistant and diabetes free despite genetic identity with NOD at numerous chromosomal regions containing previously described insulin-dependent diabetes (Idd) genes, including the strongly diabetogenic H2g7 major histocompatibility complex (MHC) haplotype. The present study revealed BKs-derived genome on segments of chromosomes (Chr) 1, 2, 4, 5, 7, 11, 12, and 18, approximating 11.6% of the total NOR genome analyzed. (NOD x NOR)F2 segregation analysis was employed to identify chromosomal regions in NOR containing Idd resistance alleles. IDDM developed in 33% (10/30) of F1 females, and 29.3% (36/123) of F2 females aged to 1 yr. A previously unrecognized diabetes resistance locus (designated Idd13r) strongly protective in homozygous state was identified on NOR Chr 2 in linkage with the Il1 alpha structural gene. The existence of this locus was confirmed by construction of a NOD stock congenic for NOR-derived markers on Chr 2. Our analysis shows the utility of RCS and congenic stocks for the identification and isolation of non-MHC genes with strong antidiabetogenic functions.