Abstract
BackgroundThe effects of nutrition on testis mass in the sexually mature male have long been known, however, the cellular and molecular processes of the testis response to nutrition was not fully understood.MethodsWe tested whether the defects in spermatogenesis and increases in germ cell apoptosis in the testis that are induced by under-nutrition are associated with changes in mRNA expression and pre-mRNA alternative splicing using groups of 8 male sheep fed for a 10% increase or 10% decrease in body mass over 65 days.ResultsWe 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 expression changed in parallel with variations in germ cell numbers, testis size, and spermatogenesis. Furthermore, pairs of 269 mRNAs and 48 miRNAs were identified on the basis of target prediction. The regulatory effect of miRNAs on mRNA expression, in combination with functional analysis, suggests that these miRNAs are involved in abnormal reproductive morphology, apoptosis and male infertility. Nutrition did not affect the total number of alternative splicing events, but affected 206 alternative splicing events. A total of 159 genes, including CREM, SPATA6, and DDX4, were differentially spliced between dietary treatments, with functions related to RNA splicing 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.ConclusionsOur findings on significant changes in mRNAs and pre-mRNA alternative splicing under-nutrition suggest that they may partly explain the disruption of spermatogenesis and the increase germ cell apoptosis. However, more research is required to verify their causal effects in regulating spermatogenesis and germ cell apoptosis.
Highlights
The effects of nutrition on testis mass in the sexually mature male have long been known, the cellular and molecular processes of the testis response to nutrition was not fully understood
We have recently found that the expression of a number of miRNAs is affected by nutrition in sexually mature male sheep, and most of the predicted targets of the differentially expressed miRNAs were mainly involved in reproductive system development and function [10]
We found over 2,000 mRNAs that were differentially expressed between treatments, with over 1,000 mRNAs, including TP53 and Claudin 11, that were more highly expressed in underfed than in well-fed sheep
Summary
The effects of nutrition on testis mass in the sexually mature male have long been known, the cellular and molecular processes of the testis response to nutrition was not fully understood. The effects of nutrition on testis mass in the sexually mature male have long been known, as has the direct relationship between testicular mass and sperm production [2]. MiRNAs are small (~22 nucleotides) endogenous RNAs that negatively regulate gene expression by targeting the 3′untranslated region (3′UTR) [8] and/or coding region [9] of mRNAs. We have recently found that the expression of a number of miRNAs is affected by nutrition in sexually mature male sheep, and most of the predicted targets of the differentially expressed miRNAs were mainly involved in reproductive system development and function [10]. We decided to profile mRNA expression in the testes of well-fed and underfed male sheep using RNA-seq so we could explore the relationships between the miRNAs we had identified and their putative targets
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