Lin28a promotes self-renewal and proliferation of dairy goat spermatogonial stem cells (SSCs) through regulation of mTOR and PI3K/AKT.

Fanglin Ma,Na Li,Guangpeng Li,Furong Tang,Xin He,Chongyang Wu,Bowen Niu,Liming Zheng,Zhe Zhou,Jinlian Hua

doi:10.1038/srep38805

Abstract

Lin28a is a conserved RNA-binding protein that plays an important role in development, pluripotency, stemness maintenance, proliferation and self-renewal. Early studies showed that Lin28a serves as a marker of spermatogonial stem cells (SSCs) and promotes the proliferation capacity of mouse SSCs. However, there is little information about Lin28a in livestock SSCs. In this study, we cloned Capra hircus Lin28a CDS and found that it is evolutionarily conserved. Lin28a is widely expressed in different tissues of Capra hircus, but is expressed at a high level in the testis. Lin28a is specifically located in the cytoplasm of Capra hircus spermatogonial stem cells and may also be a marker of dairy goat spermatogonial stem cells. Lin28a promoted proliferation and maintained the self-renewal of GmGSCs-I-SB in vivo and in vitro. Lin28a-overexpressing GmGSCs-I-SB showed an enhanced proliferation rate, which might be due to increased PCNA expression. Moreover, Lin28a maintained the self-renewal of GmGSCs-I-SB by up-regulating the expression of OCT4, SOX2, GFRA1, PLZF and ETV5. Furthermore, we found that Lin28a may activate the AKT, ERK, and mTOR signaling pathways to promote the proliferation and maintain the self-renewal of GmGSCs-I-SB.

Highlights

Lin[28], a conserved RNA-binding protein, was first characterized in Caenorhabditis elegans as a heterochronic gene that controls developmental timing[1,2]
Semi-quantitative room temperature (RT)-PCR analysis showed that Lin28a is widely expressed in various dairy goat organs, including the testis, lung, heart, liver, spleen, kidney and muscle
Immunofluorescence staining showed that Lin28a is located in the cytoplasm of the dairy goat spermatogonia and spermatogonial stem cells (Fig. 1C)

Summary

Introduction

Lin[28], a conserved RNA-binding protein, was first characterized in Caenorhabditis elegans as a heterochronic gene that controls developmental timing[1,2]. Lin[28] is highly expressed in embryonic stem cells (ESCs), but its expression is directly repressed by Lin-4 and Let-7 miRNA upon differentiation[2,3]. Lin[28] expression was directly repressed in ESCs by Lin-4 and Let-7 miRNA upon differentiation[2,3]. SSCs in adult male testis balance self-renewal and differentiation to maintain spermatogenesis[13,15]. Lin28a was expressed in undifferentiated spermatogonia[16]. Clonal expansion of progenitor TA, A undifferentiated spermatogonia was impaired when Lin28a was conditionally deleted in the adult male mouse germline[17]. AKT and mTOR are the key signals that regulate the balance between self-renewal and differentiation of SSCs20. The activated Ras/ERK1/2 pathway promotes the maintenance and self-renewal of dairy goat SSCs23

Methods

Results

Conclusion