Prdm9 Intersubspecific Interactions in Hybrid Male Sterility of House Mouse.

The classical definition posits hybrid sterility as a phenomenon when two parental taxa each of which is fertile produce a hybrid that is sterile. The first hybrid sterility gene in vertebrates, Prdm9, coding for a histone methyltransferase, was identified in crosses between two laboratory mouse strains derived from Mus mus musculus and M. m. domesticus subspecies. The unique function of PRDM9 protein in the initiation of meiotic recombination led to the discovery of the basic molecular mechanism of hybrid sterility in laboratory crosses. However, the role of this protein as a component of reproductive barrier outside the laboratory model remained unclear. Here, we show that the Prdm9 allelic incompatibilities represent the primary cause of reduced fertility in intersubspecific hybrids between M. m. musculus and M. m. domesticus including 16 musculus and domesticus wild-derived strains. Disruption of fertility phenotypes correlated with the rate of failure of synapsis between homologous chromosomes in meiosis I and with early meiotic arrest. All phenotypes were restored to normal when the domesticus Prdm9dom2 allele was substituted with the Prdm9dom2H humanized variant. To conclude, our data show for the first time the male infertility of wild-derived musculus and domesticus subspecies F1 hybrids controlled by Prdm9 as the major hybrid sterility gene. The impairment of fertility surrogates, testes weight and sperm count, correlated with increasing difficulties of meiotic synapsis of homologous chromosomes and with meiotic arrest, which we suppose reflect the increasing asymmetry of PRDM9-dependent DNA double-strand breaks.

HORMAD2 methylation-mediated epigenetic regulation of gene expression in thyroid cancer.

This study is aimed to investigate the methylation level of candidate genes and its impact on thyroid carcinoma (THCA) development. Infinium Human Methylation 450 BeadChip Arrays by Illumina (Illumina HM450K) was the most popular CpG microarray platform widely used in biological and medical research. The methylation level of differentially expressed genes and their corresponding CpG sites were analysed by R programme. The expression of HORMAD2 was evaluated by qRT-PCR and Western blot, while the methylation level was examined via methylation-specific PCR. Cell viability, metastasis, cell cycle and apoptosis were detected by MTT assay, transwell and wound healing assay and flow cytometry, respectively, after treatment with 5-aza-2'-deoxycytidine (5-Aza). Tumour formation assay was used to analyse thyroid tumour growth in nude mice in vivo. The methylation levels of all 116 differentially expressed genes were analysed. HORMAD2 was significantly hypermethylated and its mRNA expression was inhibited in THCA cells. After treatment with 5-Aza, HORMAD2 expression was up-regulated in THCA cells and its overexpression can suppress thyroid cancer cell viability, mobility and invasiveness remarkably. Up-regulation of HORMAD2 in THCA cells could prolong G0/G1 phase and shorten S phase to impede cell mitosis as well as promote thyroid cancer cells apoptosis. Furthermore, tumour formation assay showed that increased HORMAD2 level impeded tumour growth in vivo. Hypermethylation of HORMAD2 could induce THCA progression, while hypomethylation of HORMAD2 retard cell growth and mobility and facilitate apoptosis through increasing its mRNA expression.

A homozygous stop codon in HORMAD2 in a patient with recurrent digynic triploid miscarriage.

BACKGROUND: Recurrent miscarriage (RM) affects 1% to 5% of couples trying to conceive. Despite extensive clinical and laboratory testing, half of the RM cases remain unexplained. We report the genetic analysis of a couple with eight miscarriages and the search for their potential genetic etiology. METHODS: Short tandem repeat (STR) markers, single nucleotide polymorphic (SNP) microarray, and human DNA methylation microarray were used to analyze the genotypes of two miscarriages. Exomes sequencing was performed on DNA from the two partners and identified variants were validated by Sanger sequencing. RESULTS: STR marker genotyping demonstrated that the two available miscarriages are triploid digynic and resulted from the failure of Meiosis II. SNP microarray analysis revealed an additional Meiosis I abnormality that is the segregation of the two maternal homologous chromosomes in one triploid miscarriage. Whole-exome sequencing on DNA from the two partners identified candidate variants only in the female partner in two genes with roles in female reproduction, a missense in EIF4ENIF1 (OMIM 607445) and a stop gain in HORMAD2 (OMIM 618842). EIF4ENIF1 is a eukaryotic translation initiation factor 4E nuclear import factor required for the oocyte germinal vesicle breakdown, and HORMAD2 is part of the synaptonemal complex that was hypothesized to act as a checkpoint mechanism to eliminate oocytes with asynapsis during meiotic prophase I in mice. CONCLUSION: While both genes may contribute to the phenotype, the Meiosis I abnormalities in the conceptions favor the causal role of HORMAD2 in the etiology of RM in this couple. This report illustrates the importance of comprehensively analyzing the products of conception to guide the search for the genetic causation of RM.

Genic and chromosomal components of Prdm9-driven hybrid male sterility in mice (Mus musculus).

Hybrid sterility contributes to speciation by preventing gene flow between related taxa. Prdm9, the first and only hybrid male sterility gene known in vertebrates, predetermines the sites of recombination between homologous chromosomes and their synapsis in early meiotic prophase. The asymmetric binding of PRDM9 to heterosubspecific homologs of Mus musculus musculus × Mus musculus domesticus F1 hybrids and increase of PRDM9-independent DNA double-strand break hotspots results indificult- to- repair double-strand breaks, incomplete synapsis of homologous chromosomes, and meiotic arrest at the first meiotic prophase. Here, we show that Prdm9 behaves as a major hybrid male sterility gene in mice outside the Mus musculus musculus × Mus musculus domesticus F1 hybrids, in the genomes composed of Mus musculus castaneus and Mus musculus musculus chromosomes segregating on the Mus musculus domesticus background. The Prdm9cst/dom2 (castaneus/domesticus) allelic combination secures meiotic synapsis, testes weight, and sperm count within physiological limits, while the Prdm9msc1/dom2 (musculus/domesticus) males show a range of fertility impairment. Out of 5 quantitative trait loci contributing to the Prdm9msc1/dom2-related infertility, 4 control either meiotic synapsis or fertility phenotypes and 1 controls both, synapsis, and fertility. Whole-genome genotyping of individual chromosomes showed preferential involvement of nonrecombinant musculus chromosomes in asynapsis in accordance with the chromosomal character of hybrid male sterility. Moreover, we show that the overall asynapsis rate can be estimated solely from the genotype of individual males by scoring the effect of nonrecombinant musculus chromosomes. Prdm9-controlled hybrid male sterility represents an example of genetic architecture of hybrid male sterility consisting of genic and chromosomal components.

The Phenotypic Difference of IgA Nephropathy and its Race/Gender-dependent Molecular Mechanisms.

IgA nephropathy (IgAn), defined by the pre dominant de position of IgA in the glomerular mesangium, is the most common form of GN throughout the world. However, its incidence, sex distribution, clinical presentation, and progression and pathogenic initiating factors are largely variable and do not fit such a simple definition. To assess the heterogeneity of this disease, we recently conducted a clinical survey on the presentation and clinical management of patients with IgAn in Europe and Japan. This clinical survey highlights similarities and differences in patients from different cont inents. The survey revealed obvious differences between nations in the frequency of gastrointestinal complications, including inflammatory bowel diseases (IBD) and celiac disease, which were more frequent in European patients. Such findings are compatible with susceptibility loci related to intestinal immunity and IBD in recent genome wide association studies (GWAS) on IgAn. However, most of the molecules in these mucosal-related loci fulfill the immunologic function not only of gut-associated lymphoid tissue (GALT), but also nasopharyngeal/bronchial-associated lymphoid tissues (NALT/BALT). Indeed, a similar frequency of macrohematuria coinciding with upper respiratory infection, a hallmark manifestation of this disease, was found in the survey, emphasizing the pathogenic roles of these molecules in the NALT/BALT of patients with IgAn. Recent experimental and clinical studies including GWAS on multiple common infections and IBD indicate immune crosstalk between GALT and NALT/BALT, and some related mediators, such as TNF superfamily ligands (APRIL/BAFF). This review explains the epidemiologic heterogeneity of this disease with the clinical survey, and discusses race and sex-dependent molecular mechanisms.

Association of polymorphisms at HORMAD2 and prognosis in advanced non-small-cell lung cancer patients.

BACKGROUND: Cancer-testis (CT) genes are predominantly expressed in the testis and are ectopically activated in a wide range of cancers. The expression of CT antigens has been shown to significantly affect the survival of patients with non-small-cell lung cancer (NSCLC). Recently, a genome-wide association study (GWAS) and expression analysis have identified a novel CT gene (HORMAD2) associated with lung cancer risk in Han Chinese people. Thus, the aim of this study is to evaluate the potential prognostic value of HORMAD2 polymorphisms in Han Chinese patients with advanced NSCLC and undergoing first-line platinum-based chemotherapy. MATERIALS AND METHODS: We selected eight single-nucleotide polymorphisms (SNPs) of HORMAD2 with the potential function of affecting the binding of transcription factors, and we genotyped these SNPs in 303 patients with advanced NSCLC using the MassARRAY platform. All patients were treated with first-line platinum-based chemotherapy but without surgery. Log-rank test and Cox proportional hazard models were used for the survival analyses. RESULTS: Four SNPs at HORMAD2 (rs9620953, rs8135823, rs5753025 and rs9625921) were significantly associated with the survival of advanced NSCLC patients. Among these, patients with the rs9620953 T allele had a significantly reduced risk of death compared to those with the C allele (additive model: HR, 0.53, 95%CI, 0.32-0.89, P=0.016; dominant model: HR, 0.50, 95%CI, 0.29-0.84, P=0.010). Similarly, the G allele at rs8135823 could decrease the death risk of NSCLC patients compared to the T allele (additive model: HR, 0.63, 95%CI, 0.41-0.95, P=0.028; dominant model: HR, 0.60, 95%CI, 0.39-0.93, P=0.022). Furthermore, both the rs5753025 C allele and the rs9625921 G allele also decreased the death risk in NSCLC in different genetic models (additive model for rs5753025: HR, 0.80, 95%CI, 0.65-0.98, P=0.032; heterozygote model for rs9625921: HR, 0.71, 95%CI, 0.51-0.99, P=0.040). In the joint effect analyses, we found that patients with one, two, and three to eight favorable alleles had a better survival compared with patients carrying no alleles. CONCLUSIONS: These findings indicate that polymorphisms at the CT gene HORMAD2 might be involved in the prognosis of advanced NSCLC in Han Chinese. Further larger and functional studies are needed to confirm the results.