HSP70 from the Antarctic sea urchin Sterechinus neumayeri: molecular characterization and expression in response to heat stress

Marcelo González-Aravena,César A Cárdenas,Camila Calfio,Jorn Bethke,Luis Mercado,Byron Morales-Lange,Julien De Lorgeril

doi:10.1186/s40659-018-0156-9

Abstract

BackgroundHeat stress proteins are implicated in stabilizing and refolding denatured proteins in vertebrates and invertebrates. Members of the Hsp70 gene family comprise the cognate heat shock protein (Hsc70) and inducible heat shock protein (Hsp70). However, the cDNA sequence and the expression of Hsp70 in the Antarctic sea urchin are unknown.MethodsWe amplified and cloned a transcript sequence of 1991 bp from the Antarctic sea urchin Sterechinus neumayeri, experimentally exposed to heat stress (5 and 10 °C for 1, 24 and 48 h). RACE-PCR and qPCR were employed to determine Hsp70 gene expression, while western blot and ELISA methods were used to determine protein expression.ResultsThe sequence obtained from S. neumayeri showed high identity with Hsp70 members. Several Hsp70 family features were identified in the deduced amino acid sequence and they indicate that the isolated Hsp70 is related to the cognate heat shock protein type. The corresponding 70 kDa protein, called Sn-Hsp70, was immune detected in the coelomocytes and the digestive tract of S. neumayeri using a monospecific polyclonal antibody. We showed that S. neumayeri do not respond to acute heat stress by up-regulation of Sn-Hsp70 at transcript and protein level. Furthermore, the Sn-Hsp70 protein expression was not induced in the digestive tract.ConclusionsOur results provide the first molecular evidence that Sn-Hsp70 is expressed constitutively and is non-induced by heat stress in S. neumayeri.

Highlights

Heat stress proteins are implicated in stabilizing and refolding denatured proteins in vertebrates and invertebrates
The aim of this study was to characterize the heat shock protein Hsp70 gene and construct and test a new antibody for protein expression analysis in the coelomocytes of S. neumayeri, and to determine whether its expression is modulated after heat stress
Identification of the Hsp70 transcript expressed in S. neumayeri By PCR approach using primers designed from a conserved region of Hsp70 of invertebrates and vertebrates, we obtained a 1991 bp cDNA that codes for an open read frame of 651 amino acids

Summary

Introduction

Heat stress proteins are implicated in stabilizing and refolding denatured proteins in vertebrates and invertebrates. The success of any organism relies on its niche adaptation and on its ability to survive to environmental variation (e.g. maintaining homeostasis in stress situations). In this regard, the induction of heat shock proteins (e.g. Hsp70) has been widely reported across different taxa [1]. High mortality of krill has been reported near to Carlini Station related to significant increases of particulate matter of glacial origin produce by increased temperature [7]. Under this scenario, it has been experimentally determined that Antarctic marine

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