[NSD1 regulates H3K36me2 in the pathogenesis of non-obstructive azoospermia]

To explore the role of nuclear receptor-binding SET-domain protein 1 (NSD1) in the pathogenesis of nonobstructive azoospermia (NOA) by regulating the expressions of relevant genes.

We detected the expression of NSD1 in the testis tissue of 7 male patients with obstructive azoospermia (OA) and 18 with NOA by qPCR and immunofluorescence assay, and determined the modification level of H3K36me2 in the testes of two groups of patients by immunofluorescence staining, Western blot and immunoprecipitation (IP). We examined the difference in the enrichment of H3K36me2 in the testis tissue by chromatin IP-based sequencing (ChIP-Seq), analyzed the genomic distribution and target genes using bioinformatics, and verified the expression levels of the target genes in the testes of the two groups of patients by qPCR.

Compared with the patients with OA, those with NOA showed dramatically decreased mRNA and protein expressions of NSD1 (P=0.000 8). The binding of NSD1 to H3K36me2 was observed in the testis tissue of both the two groups of patients, while the modification level of H3K36me2 was evidently reduced in the NOA males. H3K36me2 was distributed mainly in the intergenic region in the testes of the two groups of patients, but the enrichment of H3K36me2 was obviously decreased in the NOA group. The differentially H3K36me2-enriched genes were involved in various biological processes, including tissue development, and cell morphogenesis. Results of ChIP-Seq and qPCR showed significantly down-regulated expressions of the target genes KIT, SPO11 and ACRV1 in the testis tissue of the NOA males compared with those in the OA patients (P<0.01).

The levels of NSD1 and H3K36me2 are decreased in testis tissue of the NOA patient, H3K36me2 is highly enriched in the spermatogenesis-related key genes KIT, SPO11 and ACRV1, and the down-regulated expression of NSD1 impairs spermatogenesis.