Molecular cloning and functional characterization of sarco/endoplasmic reticulum Ca 2+ ‐ ATPase from Chinese mitten crab ( Eriocheir sinensis )

Abstract

Ca2+ plays an important role in signal transduction and regulates various physiological functions of cells. The active transport of Ca2+ from the cytosol to the lumen of the sarcoplasmic or endoplasmic reticulum occurs via sarco/endoplasmic reticulum Ca2+-ATPases (SERCA). However, the function of this protein during moulting cycles remains unclear in Chinese mitten crab (Eriocheir sinensis). In this study, we cloned a cDNA encoding a putative SERCA protein from the Y-organs (moulting glands) in E. sinensis. The cloned Es-SERCA cDNA (4552 bp) included an open reading frame of 3003 bp encoding a 1000-residue protein with a predicted molecular mass of 109.60 kDa. The predicted Es-SERCA protein was clustered with those from other arthropods in phylogenetic analysis. Further, qPCR revealed that Es-SERCA was widely expressed in in all tested tissues with the highest expression in the muscle, followed by the eyestalks, intestines, hepatopancreas, Y-organs and gills. The stage-specific fluctuations among different tissues indicated a functional role of SERCA in calcium homeostasis. The relative mRNA level of the Es-SERCA in Y-organs during the moulting cycle was similar to the level trend of ecdysteroid concentration in haemolymph, indicating that Ca2+ signalling stimulated ecdysteroid synthesis in Y-organs. Altogether, our study provides a reference for further research on the molecular mechanisms of the moulting in E. sinensis.