Comparative Transcriptomics Reveal Key Sheep (Ovis aries) Hypothalamus LncRNAs that Affect Reproduction.

Zhuangbiao Zhang,Wenping Hu,Qiuyue Liu,Shangquan Gan,Ran Di,Xiaosheng Zhang,Xiangyu Wang,Jishun Tang,Jinlong Zhang,Mingxing Chu

doi:10.3390/ani9040152

Abstract

Simple SummaryThe hypothalamus has an important role in sheep reproduction. In this study, the key long noncoding RNAs (lncRNAs) associated with sheep fecundity were detected and characterized using the RNA Sequencing technique in sheep hypothalami. The results indicated that several key lncRNAs may affect crucial reproductive processes by differentially influencing the expression of their target genes in polytocous sheep in the follicular phase (PF) vs. monotocous sheep in the follicular phase (MF) and in polytocous sheep in the luteal phase (PL) vs. monotocous sheep in the luteal phase (ML). These results provide an insight into the prolificacy mechanism in sheep without FecB mutation in terms of the hypothalamus.The diverse functions of long noncoding RNAs (lncRNAs), which execute their functions mainly through modulating the activities of their target genes, have been have been widely studied for many years (including a number of studies involving lncRNAs in the ovary and uterus). Herein, for the first time, we detect lncRNAs in sheep hypothalami with FecB++ through RNA Sequencing (RNA-Seq) and identify a number of known and novel lncRNAs, with 622 and 809 found to be differentially expressed in polytocous sheep in the follicular phase (PF) vs. monotocous sheep in the follicular phase (MF) and polytocous sheep in the luteal phase (PL) vs. monotocous sheep in the luteal phase (ML), respectively. Then, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed based on the predicted target genes. The most highly enriched GO terms (at the molecular function level) included carbonyl reductase (NADPH), 15-hydroxyprostaglandin dehydrogenase (NADP+), and prostaglandin-E2 9-reductase activity in PF vs. MF, and phosphatidylinositol-3,5-bisphosphate binding in PL vs. ML was associated with sheep fecundity. Interestingly, the phenomena of valine, leucine, and isoleucine degradation in PL vs. ML, and valine, leucine, and isoleucine biosynthesis in PF vs. MF, were present. In addition, the interactome of lncRNA and its targets showed that MSTRG.26777 and its cis-targets ENSOARG00000013744, ENSOARG00000013700, and ENSOARG00000013777, and MSTRG.105228 and its target WNT7A may participate in the sheep reproductive process at the hypothalamus level. Significantly, MSTRG.95128 and its cis-target Forkhead box L1 (FOXG1) were shown to be upregulated in PF vs. MF but downregulated in PL vs. ML. All of these results may be attributed to discoveries of new candidate genes and pathways related to sheep reproduction, and they may provide new views for understanding sheep reproduction without the effects of the FecB mutation.

Highlights

Reproduction involves many organs and expressed genes
The validation results for the six long noncoding RNAs (lncRNAs) (Table 3) selected to substantiate the accuracy of sequencing are displayed in Figure 4; the results indicate that there is a similar expression pattern of lncRNAs generated from RNA Sequencing (RNA-Seq) and reverse-transcription quantitative polymerase chain reaction (RT-qPCR) data
We initially identified a number of lncRNAs in the hypothalamus from PF, MF, PL, and ML via RNA-seq

Summary

Introduction

Strict regulation of the central nervous system (CNS) and endocrine system, especially related to hormone synthesis and release from the hypothalamus–pituitary–gonadal axis [1], is necessary to achieve reproduction. The importance of GnRH for reproduction has been proven, the mechanisms by which GnRH expression is increased have not been elucidated [4]. Small Tail Han Sheep (STH), an indigenous sheep breed with hyper-fecundity (normally having more than one offspring per birth), has been investigated over many years, especially regarding its reproductive traits. STH with the FecB++ genotype have only one offspring per birth. In some cases, STH carrying FecB++ have more than one offspring per birth [8], other potential mechanisms remain to be understood

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Conclusion