Lipoprotein Lipase Gene in Red Sea Bream; A Summarized Paper

Abstract

Lipoprotein lipase (LPL) is a key enzyme of lipid metabolism. The elucidation of the structure, function and regulation of LPL is important for understanding the lipid metabolism in fish. Recently, we have cloned the LPL gene of red sea bream (Pagrus major) and characterized it by cDNA and genomic structure analysis. Subsequently, using the cloned sequence, gene expression has been investigated. We review in this report the features of red sea bream LPL gene. Red sea bream LPL gene spans 6.3 kb of the genome and is organized into ten exons and nine introns. The deduced amino acid sequences showed high degree of similarities to the LPLs of other animals. In a 1.1 kb 5' flanking region, the homologous sequences for the response elements of Insulin, glucocorticoid and thyroid hormone were detected. These results suggest the hormonal regulation of the LPL gene expression. Red sea bream LPL gene was expressed in various tissues including adipose tissue, heart, liver (hepatopancreas) and muscle. A fourteen-week feeding experiment was conducted to investigate the effects of feeding condition and dietary lipid level. The results suggest that LPL gene expression in visceral adipose tissue and liver is regulated in tissue-specific manner. The expression level in adipose tissue was down-regulated during starvation whereas it was up-regulated in liver. The effects of dietary lipid level on the gene expression were not observed. These results will facilitate further study on the function and regulation of the LPL in fish.