Investigation of the lncRNA THOR in Mice Highlights the Importance of Noncoding RNAs in Mammalian Male Reproduction.

Lin Zhou,Hao Yu,Anbei Wang,Hongsheng Ouyang,Jianing Li,Daxin Pang,Jinsong Liu,Ying Liu

doi:10.3390/biomedicines9080859

Abstract

THOR is a highly conserved testis-specific long noncoding RNA (lncRNA). The interaction between THOR and the development of the male reproductive system remains unclear. Herein, CRISPR/Cas9 technology was used to establish a stable THOR-deficient mouse model, and the relationship between THOR and the fertility of adult male mice was investigated. The male mice in which THOR was deleted were smaller than the WT male mice. Moreover, their survival rate was reduced by 60%, their fertility was reduced by 50%, their testicular size and sperm motility were reduced by 50%, their testicular cell apoptosis was increased by 7-fold, and their ratio of female-to-male offspring was imbalanced (approximately 1:3). Furthermore, to elucidate the mechanisms of male reproductive system development, the mRNA levels of THOR targets were measured by qRT-PCR. Compared with WT mice, the THOR-deficient mice exhibited significantly decreased mRNA levels of IGF2BP1, c-MYC, IGF1, and IGF2. MEK-ERK signaling pathway expression was downregulated as determined by Western blot. We found that THOR targeted the MER-ERK signaling pathway downstream of IGF2 by binding to IGF2BP1 and affected testicular and sperm development in male mice. These results may also provide perspectives for exploring the roles of lncRNAs in human reproductive development and the pathogenesis and potential therapeutic targets of infertility.

Highlights

75% of the genes in mammalian genomes can be transcribed, but less than 2% have the ability to encode proteins [1,2]
We used Quantitative real-time PCR (qRT-PCR) primers located outside the gene deletion region to detect the decreased expression of THOR (Figure S2)
Transgenic THOR knockout produced fertilization defects in zebrafish and conferred resistance to melanoma onset [11]. While these results indicate that THOR plays an important role in male reproductive system development, little is known about its role in mammalian testis and sperm development

Summary

Introduction

75% of the genes in mammalian genomes can be transcribed, but less than 2% have the ability to encode proteins [1,2]. Most transcripts that do not encode proteins are called noncoding RNAs and include short and long noncoding RNAs (lncRNAs) [3,4]. Genes that do not participate in the mechanisms of individual regulatory networks [6,7]. Recent studies have confirmed that lncRNAs can act as molecular signals, scaffolds, or enhancers/inhibitors to regulate important cell behaviors, including survival, growth, proliferation, and apoptosis resistance [8,9]. The molecular mechanisms of cancer/testis lncRNAs in cancer metastasis are largely unknown and need to be fully elucidated [10]

Methods

Results

Conclusion