Effects of insulin, triiodothyronine and fat soluble vitamins on adipocyte differentiation and LPL gene expression in the stromal-vascular cells of red sea bream, Pagrus major

• Published in: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology Vol. 144; no. 3; pp. 326 - 333
• Main Authors: Oku, Hiromi, Tokuda, Masaharu, Okumura, Takuji, Umino, Tetsuya
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01.07.2006
• Subjects: Adipocyte; Adipocytes - drug effects; Animals; Cell Differentiation - drug effects; Cells, Cultured; Differentiation; Gene Expression; Insulin - pharmacology; Intra-Abdominal Fat - cytology; Lipoprotein lipase (LPL); Lipoprotein Lipase - metabolism; Marine; Pagrus major; Red sea bream; Sea Bream - metabolism; Stromal Cells - drug effects; Stromal-vascular cells; Teleost; Triiodothyronine - pharmacology; Vitamins - pharmacology; Teleost; Adipocyte; Stromal-vascular cells; Pagrus major; Red sea bream; Differentiation; Lipoprotein lipase (LPL)
• ISSN: 1096-4959; 1879-1107
• DOI: 10.1016/j.cbpb.2006.03.008

Various kinds of hormones including insulin, triiodothyronine (T 3) and fat-soluble vitamins have been proposed as mediators of adipocyte differentiation in mammals. To investigate the factors which are responsible for fish adipocyte differentiation, we developed a serum-free culture system of stromal-vascular cells of red sea bream adipose tissue and examined the effects of bovine insulin, T 3, and fat-soluble vitamins (all- trans retinoic acid, retinyl acetate and 1,25-dihydroxyvitamin D 3) on the differentiation-linked expression of the lipoprotein lipase (LPL) gene. As assessed by the increase in LPL gene expression after 3 day cultivation, like in mammalian adipocytes, insulin enhanced the adipocyte differentiation in a concentration-dependent manner. During 2 week cultivation, bovine insulin promoted lipid accumulation in differentiating adipocytes concentration-dependently until the terminal differentiation. These results indicate that the differentiation of fish adipocytes is inducible by insulin alone. T 3 alone had no effect but enhanced the differentiation-linked LPL gene expression in the presence of insulin. Fat-soluble vitamins, unlike in mammalian adipocytes, did not show any significant effects. The method developed in this study should be of interest for the characterization of factors involved in fish adipocyte differentiation.