Characterization and function analysis of a glucose-regulated protein 78 gene in Neocaridina denticulata sinensis

Endoplasmic reticulum (ER) homeostasis is vital to cell physiological functions. Glucose-regulated protein 78 (GRP78) is a molecular chaperone considered a sensor of ER stress and participates in maintaining ER homeostasis. However, very few studies have provided detailed descriptions of crustacean GRP78 genes. The complete coding sequence of the GRP78 of Neocaridina denticulata sinensis was obtained and termed NdGRP78 in this study. Sequence analysis showed that the open reading frame of NdGRP78 encodes a protein of 656 amino acid residues, and the encoded protein includes three heat shock proteins 70 (HSP70) family conservational motifs, one ATP/GTP binding site A, and one ER homolog region. Multiple sequence alignments demonstrated that the sequences of these key protein functional domains were highly conserved. Phylogenetic analysis revealed that the NdGRP78 protein belongs to a member of the HSP70 family. The NdGRP78 mRNA was detected in all tested tissues by realtime fluorescence quantitative PCR (qPCR), suggesting that the NdGRP78 mRNA was the constituent expression in N. denticulata sinensis. The in-situ hybridization result showed that the expression of NdGRP78 mRNA occurred in all types of hepatopancreas cells. Furthermore, the NdGRP78 expression was significantly increased when shrimp were transferred into Vibrio parahaemolyticus-EGFP infected conditions, low or high temperature, and hypoxia. The above results indicate that NdGRP78 expressions were associated with stress responses. This study provided a theoretical support to the good understanding of the role of NdGRP78 in response to different types of environmental stress tolerance.