Molecular Characterization of Hsp47 in Grass Carp (<i>Ctenopharyngodon idella</i>) and Its Correlation with Type I Collagen in Response to Fish Aerobic Exercise

Heat shock protein 47 (Hsp47) is a collagen-specific molecular chaperone that is indispensable for molecular maturation of collagen. In this study, <i>hsp47</i> and <i>hsp47-like</i> cDNAs were cloned and characterized in grass carp (<i>Ctenopharyngodon idella</i>). The cDNAs were 1212 and 1218 base pairs long, respectively, and included an open reading frame encoding 403 and 405 amino acids. The molecular phylogeny based on the deduced amino acid sequences indicated that the correct sequences of the <i>hsp47</i> and <i>hsp47-like</i> cDNA were obtained and the deduced proteins clustered distinctly into teleost clades. Primary structure analysis and characterization of Hsp47 and Hsp47-like shared the basic structure and biofunctions of Hsp47 in vertebrates. The spatial pattern of gene expression revealed that <i>hsp47</i> and <i>hsp47-like</i> were relatively ubiquitous in different tissues and highly expressed in heart and skin. The expression levels of <i>hsp47</i> and <i>hsp47-like</i> and type I collagen mRNAs varied similarly in different tissues. Type I collagen content increased significantly with the increase of water velocity in the muscle of grass carp in response to aerobic exercise. Among the gene expression changes of <i>hsp47</i>, <i>hsp47-like</i>, <i>col1a1</i> and <i>col1a2</i> in muscle that occurred in response to aerobic exercise, the change of type I collagen was most strongly correlated with <i>hsp47</i> expression. Additionally, col1a1 showed the highest correlation with <i>hsp47-like</i> and <i>col1a2</i> showed the highest correlation with <i>hsp47</i>. These findings suggest that grass carp Hsp47 and Hsp47-like are closely related to type I collagen synthesis. This study firstly suggests fish aerobic exercise can improve type I collagen content and Hsp47 gene expression in muscle of grass carp.