Small Heat Shock Proteins (sHSPs) have important roles in preventing disease and promoting resistance to environmental stressors. Mutations in any one of a number of sHSPs, including HSP27 (HSPB1), HSP22 (HSPB8), alphaA-crystallin (HSPB4), or alphaB-crystallin (HSPB5) can result in neuronal degeneration, myopathy, and/or cataract in humans. Ten sHSPs are known in humans, and thirteen have been identified in teleost fish. Here we report the identification of thirteen zebrafish sHSPs. Using a combination of phylogenetic analysis and analysis of synteny, we have determined that ten are likely orthologs of human sHSPs. We have used quantitative RT-PCR to determine the relative expression levels of all thirteen sHSPs during development and in response to heat shock. Our findings indicate that most of the zebrafish sHSPs are expressed during development, and five of these genes are transcriptionally upregulated by heat shock at one or more stages of development.

Heat shock proteins (HSPs), so named for their transcriptional upregulation in response to sudden temperature elevation, are best known for their roles in chaperoning nascent proteins and preventing aggregation. Many HSPs also have functions independent of their chaperone activity. A handful of degenerative diseases, including distal hereditary motor neuropathy, axonal Charcot‐Marie‐Tooth disease, and desmin‐related myopathy, are caused by mutations in specific members of the small heat shock protein (sHSP), or alpha‐crystallin, family. However, it is not clear whether these diseases are caused by abnormal development, disturbed function, protein aggregation, or some combination of the three. We are systematically characterizing the developmental and heat shock‐induced expression of the complete zebrafish sHSP family with the aim of identifying candidates for regulating development and for helping the organism recover from the effects of environmental stressors. We have identified thirteen zebrafish sHSPs nearly all of which are expressed during development. Consistent with observations in a variety of other species, only two are upregulated by heat shock. Our combined results suggest that many sHSPs may be important during normal development and for protection and recovery from environmental stress. NIH R03EY015207 and the Essel Foundation