Heat shock proteins (chaperones) in fish and shellfish and their potential role in relation to fish health: a review

Abstract

Heat shock proteins (HSPs), also known as stress proteins and extrinsic chaperones, are a suite of highly conserved proteins of varying molecular weight (c. 16-100 kDa) produced in all cellular organisms when they are exposed to stress. They develop following up-regulation of specific genes, whose transcription is mediated by the interaction of heat shock factors with heat shock elements in gene promoter regions. HSPs function as helper molecules or chaperones for all protein and lipid metabolic activities of the cell, and it is now recognized that the up-regulation in response to stress is universal to all cells and not restricted to heat stress. Thus, other stressors such as anoxia, ischaemia, toxins, protein degradation, hypoxia, acidosis and microbial damage will also lead to their up-regulation. They play a fundamental role in the regulation of normal protein synthesis within the cell. HSP families, such as HSP90 and HSP70, are critical to the folding and assembly of other cellular proteins and are also involved in regulation of kinetic partitioning between folding, translocation and aggregation within the cell. HSPs also have a wider role in relation to the function of the immune system, apoptosis and various facets of the inflammatory process. In aquatic animals, they have been shown to play an important role in health, in relation to the host response to environmental pollutants, to food toxins and in particular in the development of inflammation and the specific and non-specific immune responses to bacterial and viral infections in both finfish and shrimp. With the recent development of non-traumatic methods for enhancing HSP levels in fish and shrimp populations via heat, via provision of exogenous HSPs or by oral or water administration of HSP stimulants, they have also, in addition to the health effects, been demonstrated to be valuable in contributing to reducing trauma and physical stress in relation to husbandry events such as transportation and vaccination.

Genome-wide identification of Hsp70 genes in channel catfish and their regulated expression after bacterial infection

“…Although heat shock proteins are traditionally regarded as being induced by heat and stresses, recent studies suggested HSPs may actually play important roles in immune responses [18]. For example, HSPs are considered to mediate humoral and cellular innate immune responses [19]; HSPs in extracellular environment serve as a danger signal to activate innate immune cells such as dendritic cells and macrophages [20][21][22].…”

Expression analysis of heat shock protein genes during Aeromonas hydrophila infection in rohu, Labeo rohita, with special reference to molecular characterization of Grp78

“…Interestingly, a host can recognize its own molecular chaperones and those of the invading bacteria. Eukaryotic Hsp genes are categorized into different families based on their function, sequence homology, and molecular weight such as HSP100, HSP90, HSP70, HSP60, HSP40, and several smaller HSP groups (Roberts et al 2010). …”

“…Hsp's activity is not limited to the postinfection stress response but can modulate the immune system as well (Roberts et al 2010). Infection regulates stress gene expression both in the host and in parasites (Henderson et al 2006).…”

Hsp70 expression in shrimp Litopenaeus vannamei in response to IHHNV and WSSV infection

“…It suggests that the induction of Hsp70 by shrimps infected with virus improves its responsiveness and decrease the mortality rate. Heat Shock Proteins (HSPs) comprise a group of highly conserved proteins that have general protective functions against pathogens in all living organisms [17]. In aquatic animals, Hsp70 has been shown to play an important role in relation to the host response to environmental pollutants, food toxins, and bacterial or viral infections [18].…”

“…Heat Shock Proteins (HSPs) comprise a group of highly conserved proteins that have general protective functions against pathogens in all living organisms [17]. In aquatic animals, Hsp70 has been shown to play an important role in relation to the host response to environmental pollutants, food toxins, and bacterial or viral infections [18]. Elucidating associations between Hsps, the immune system and pathogen resistance in shrimp represents an intriguing challenge [12].…”