Molecular cloning and expression analysis of glucose-regulated protein 78 (GRP78) gene in silkworm Bombyx mori

Abstract

GRP78 (78 kDa glucose-regulated protein), also known as BiP (immunoglobulin heavy-chain-binding protein), is an essential regulator of endoplasmic reticulum (ER) homeostasis because of its multiple functions in protein folding, ER calcium binding, and controlling of the activation of transmembrane ER stress sensors. In this report, we cloned the full-length cDNA of GRP78 from silkworm Bombyx mori (BmGRP78). It is 2645 bp, including an open reading frame (ORF) of 1977 bp encoding a polypeptide of 658 amino acids. We sequenced the ORF sequence from genomic DNA, and found only one intron (104 bp) existed in Bmgrp78 gene structure. The deduced amino acid sequence of Bmgrp78 carries the ER retention signal KDEL at its C-terminus and is highly homologous to GRP78 of Fenneropenaeus chinensis (83.59%) and Homo sapiens (80.27%). RT-PCR analysis shows that Bmgrp78 is ubiquitously expressed in tissues of silkworm. Heat shock over 35• C notably enhanced the expression of Bmgrp78 in head tissues. In response to starvation, the transcript level of Bmgrp78 in head tissues was 2.8-fold (at WS stage) and 3.2-fold (at SD1 stage) higher than the control level, but it remained stable in the midgut tissues. After silkworms were challenged by bacteria, the relative expression level of Bmgrp78 in midgut was up-regulated and reached maximal level at 24 hour after injection, and remained higher level than that of controls at about 48 hour post challenge. We infer that BmGRP78 may play important roles in chaperoning, protein folding and immune function of silkworm.

Endoplasmic Reticulum Stress–Related Genes in Yellow Catfish Pelteobagrus fulvidraco: Molecular Characterization, Tissue Expression, and Expression Responses to Dietary Copper Deficiency and Excess

“… Zhu et al (2013) indicated that the expression of grp78 in the liver of grass carp Ctenopharyngodon idella was higher than other tissues. Other studies also indicated higher Grp78 accumulation in brain ( Higashino et al 2006 ; Xi and Ma 2013 ) and heart tissue in mammals ( Oh-hashi et al 2003 ). In the present study, crt mRNA was expressed ubiquitously in every tissue, with the highest in liver and the lowest in ovary, mid-intestine, gill, and skeletal muscle.…”

“…The present study indicated that grp78 mRNA levels were the highest in liver, followed by heart and brain. The noninduced level of expression of grp78 indicated that it might play multiple functions in yellow catfish as its homologs reported in other living organisms ( Xi and Ma 2013 ). Zhu et al (2013) indicated that the expression of grp78 in the liver of grass carp Ctenopharyngodon idella was higher than other tissues.…”

Induction of stress‐ and immune‐associated genes in the Indian meal moth Plodia interpunctella against envenomation by the ectoparasitoid Bracon hebetor

“…In the mammalian system, grp78 levels are regulated by various ER stress factors such as accumulation of unfolded proteins, intracellular calcium efflux, pathological conditions, and glucose deprivation (Lee, ; Shim et al., ). In other vertebrates, grp78 levels are also changed due to thermal and pathological stresses (Luan, Li, Zhang, Wang, & Xiang, ; Xi & Ma, ). These findings suggest that the downregulation of grp78 in the feeding stage larvae after envenomation might be attributed to the shortage of nutrition supply to the cells of host insects.…”

Identification of glucose‐regulated protein 78 (grp78) cDNA from Aphis gossypii and its expression during development, heat shock and nutritional ingestion

“…As with hsc70 , grp78 is not known to respond to thermal stress in vertebrates (Lee, ). However, in studies on invertebrate species, thermal stress is shown to induce grp78 in silkworms, shrimp and overwintering gall flies, although not in red mites (Luan et al ., ; Zhang et al ., ; Yang et al ., ; Xi & Ma, ). The present study demonstrates that significant changes in the grp78 levels of A. gossypii are not induced by exposure to 0–40 °C for 1 h. Thus, it is likely that the response of grp78 to thermal stress may vary among different species of invertebrates.…”

“…GRP78 and its gene ( grp78 ) exist in various invertebrate species, although their physiological roles are only described in a few species. As in other hsp genes, grp78 is upregulated by thermal stress and pathogen infection in the silkworm Bombyx mori and the Chinese shrimp Fenneropenaeus chinensis (Luan et al ., ; Xi & Ma, ). The level of GRP78 also increases along with other HSPs to provide freezing tolerance and winter survival of gall fly larvae ( Eurosta solidaginis ) (Zhang et al ., ).…”