Genomewide identification and analysis of heat-shock proteins 70/110 to reveal their potential functions in Chinese soft-shelled turtle Pelodiscus sinensis.

Tengfei Liu,Ye Liu,Huiying Zhao,Yawen Han

doi:10.1002/ece3.5264

Abstract

Heat‐shock proteins 70/110 (Hsp70/110) are vital molecular chaperones and stress proteins whose expression and production are generally induced by extreme temperatures or external stresses. The Hsp70/110 family is largely conserved in diverse animals. Although many reports have studied and elaborated on the characteristics of Hsp70/110 in various species, the systematic identification and analysis of Hsp70/110 are still poor in turtles. In this study, a genomewide search was performed, and 18 candidate PsHSP70/110 family genes were identified in Chinese soft‐shelled turtle, Pelodiscus sinensis. These PsHSP70/110 proteins contained the conserved “heat shock protein 70” domain. Phylogenetic analysis of PsHSP70/110 and their homologs revealed evolutionary conservation of Hsp70/110 across different species. Tissue‐specific expression analysis showed that these PsHSP70/110 genes were differentially expressed in different tissues of P. sinensis. Furthermore, to examine the putative biological functions of PsHSP70/110, the dynamic expression of PsHSP70/110 genes was analyzed in the testis of P. sinensis during seasonal spermatogenesis following germ cell apoptosis. Notably, genes such as PsHSPA1B‐L, PsHSPA2, and PsHSPA8 were significantly upregulated in P. sinensis testes along with a seasonal decrease in apoptosis. Protein interaction prediction revealed that PsHSPA1B‐L, PsHSPA2, and PsHSPA8 may interact with each other and participate in the MAPK signaling pathway. Moreover, immunohistochemical analysis showed that PsHSPA1B‐L, PsHSPA2, and PsHSPA8 protein expression was associated with seasonal temperature variation. The expression profiling and interaction relationships of the PsHSPA1B‐L, PsHSPA2, and PsHSPA8 proteins implied their potential roles in inhibiting the apoptosis of germ cells in P. sinensis. These results provide insights into PsHSP70/110 functions and will serve as a rich resource for further investigation of HSP70/110 family genes in P. sinensis and other turtles.

Highlights

Heat‐shock proteins (Hsps), which were first reported in Drosophila, are ubiquitously found in bacteria, plants, and animals (Arya, Mallik, & Lakhotia, 2007)
We focused on the mRNA and protein expression of PsHSP70/110 genes to inves‐ tigate their putative roles in germ cell apoptosis following seasonal temperature variation
Tissue‐specific expres‐ sion analysis revealed that most PsHSP70/110 genes were constitu‐ tively expressed in different tissues of P. sinensis, which suggested that PsHSP70/110 genes may be important for organismic homeo‐ stasis

Summary

| INTRODUCTION

Heat‐shock proteins (Hsps), which were first reported in Drosophila, are ubiquitously found in bacteria, plants, and animals (Arya, Mallik, & Lakhotia, 2007). The primary goals of this study were to systematically identify candidate PsHSP70/110 family genes based on the whole‐genome sequence of P. sinensis and to analyze their classification, conserved structures, and phylogenetic relationships. We focused on the mRNA and protein expression of PsHSP70/110 genes to inves‐ tigate their putative roles in germ cell apoptosis following seasonal temperature variation. These results will provide useful information for the exploration of PsHSP70/110 functions in P. sinensis and fa‐ cilitate further investigation of Hsp70/110 family genes in turtles. The molecular weights, theoretical pI, instability index, aliphatic index, and grand average of hydropathicity (GRAVY) were calculated

| MATERIALS AND METHODS

| DISCUSSION

Findings

| CONCLUSION