ABSTRACT: We tested whether the defects in spermatogenesis and increases in germ cell apoptosis that are induced by under-nutrition are associated with changes in mRNA expression and pre-mRNA alternative splicing in the testis. Groups of 8 male sheep were fed for a 10% increase or 10% decrease in body mass over 65 days. We identified 2,243 mRNAs, including TP53 and Claudin 11, that were differentially expressed in testis from underfed and well-fed sheep (FDR < 0.1), and found that their changes in expression were associated with germ cells, testis size, cell cycle and spermatogenesis variations. Furthermore, pairs of 269 mRNAs and 48 miRNAs were indentified based on target prediction and the negative regulatory effect of miRNAs on mRNA expression with functions involved in abnormal reproductive morphology, apoptosis and male infertility. Nutrition did not affect the total number of alternative splicing junctions, but affected 1,040 alternative splicing events (FDR < 0.05, ∆PSI > 10%). A total of 788 genes, including CREM, MAP2, HIPK3 and TRa2β, were differentially spliced between dietary treatments, with functions related to protein localization, cellular metabolic process, post-translational protein modification and spermatogenesis. In addition, three gene modules were positively correlated with spermatogenesis-related phenotypic traits and negatively related to apoptosis-related phenotypic traits. Among these gene modules, seven (CFLAR, PTPRC, F2R, MAP3K1, EPHA7, APP, BCAP31) were also differentially expressed between nutritional treatments, indicating their potential as markers of spermatogenesis or apoptosis. We conclude that under-nutrition causes changes in mRNAs and pre-mRNA alternative splicing that, at least partly, contribute to disrupted spermatogenesis and increased germ cell apoptosis.
