Identification of Photoperiod-Induced LncRNAs and mRNAs in Pituitary Pars Tuberalis of Sheep.

Qing Xia,Xiaosheng Zhang,Qiuyue Liu,Jinlong Zhang,Ran Di,Mingxing Chu,Xiaofei Guo,Xiaoyun He

doi:10.3389/fvets.2021.644474

Abstract

The pituitary pars tuberalis (PT) is the regulating center of seasonal reproduction, which can sense the melatonin signal and eventually cause downstream changes of GnRH secretion through TSHβ. Recently, lncRNAs have been identified in animal reproductive-related tissues, and they play important roles in reproductive regulation. Therefore, in this study, we expect to identify photoperiod-induced lncRNAs and genes in pituitary PT of sheep by comparison of expression profiles between short photoperiod (SP) and long photoperiod (LP). Through RNA-Seq, a total of 55,472 lncRNAs were identified in pituitary PT of Sunite ewes. The number of differentially expressed (DE) genes and lncRNAs between SP and LP increased gradually with the extension of LP (from LP7 to LP42). The notable LP-induced candidate genes included EYA3, TSHB, SIX1, DCT, VMO1, AREG, SUV39H2, and EZH2, and SP-induced genes involved ENSOARG00000012585, CHGA, FOS, SOCS3, and TH. In enriched pathways for DE genes and lncRNA target genes between SP and LP, the reproduction- and circadian-related pathways were highlighted. In addition, the interactome analysis of lncRNAs and their targets implied that MSTRG.209166 and its trans-target TSHB, MSTRG.288068 and its cis-target SIX1, and ENSOARG00000026131 and its cis-target TH might participate in regulation of seasonal reproduction. Together, these results will help to determine important photoperiod-induced lncRNAs and genes and give us some new insights into the epigenetic regulation of seasonal reproduction in sheep.

Highlights

The reproductive activity of some animal species inhabiting the temperate zone is limited in specific seasons in order to maximize the survival possibility of their offspring
Several key genes for seasonal reproduction have been found in animals, including EYA3 gene in Japanese quail [38] and sheep [8], the vasoactive intestinal peptide (VIP) gene in Yangzhou goose [39], TSHB in sheep [8], TSHB and pituitary adenylate cyclase activating polypeptide (PACAP) in mice [19, 40], and CHGA and Tachykinin 1 (TAC1) in sheep [3, 7], which are mainly expressed in the pituitary PT
Combined with the results of gene differential expression, GO, and KEGG pathway enrichment analyses, some important candidate genes were screened out. They included CHGA, FOS, SOCS3, EYA3, TSHB, SIX1, GHRH, DCT, TH, VMO1, AREG, SUV39H2, and EZH2, which were mainly involved in the following pathways: reproduction-related pathways, TNF signaling pathway, circadian entrainment, and tyrosine metabolism

Summary

Introduction

The reproductive activity of some animal species inhabiting the temperate zone is limited in specific seasons in order to maximize the survival possibility of their offspring. According to the different seasons of breeding, these animals are categorized as long photoperiod (LP) breeders and short photoperiod (SP) breeders [1, 2]. Sunite sheep in China exhibit obvious seasonal reproductive behavior throughout the year, i.e., estrus from August to March of the year and anestrus from April to July [2, 4]. Seasonal reproduction is an important factor limiting the production effciency of the sheep industry; research on the molecular basis of seasonal reproduction of sheep is indispensable for possible artificial regulation of this trait in the future. The molecular mechanism and regulatory network of seasonal reproduction are not very clear until now

Objectives

Results

Conclusion