Development and Maturation of Lipoprotein Lipase in Cultured Adipose Cells
Lipoprotein lipase (LPL) is known to play in vivo a central role in the degradation of circulating triglycerides. It is synthesized and secreted by differentiated cells of mesodermal origini. In adipose tissue, as well as in other tissues, the enzyme is transported by some unknown mechanism to the luminal surface of endothelial cells where its lipolytic activity is then expressed in the presence of ApoC2-containing lipoproteins2–4. As reported below, the availability in the last decade of preadipocyte clonal lines and strains of adipose precursor cells has been a useful tool to study in vitro the status of LPL. The validity of using preadipocyte clonal lines established from mouse such as 3T3-L15, 3T3-F442A6 and Ob177 for the study of LPL relies primarily on the biochemical properties of the cells after adipose conversion8,9. The comparative properties of differentiated cells and of mature rodent adipocytes show that the specific activities of key lipolytic and lipogenic enzymes (including LPL) as well as different hormonal responses, are within the same range of magnitude in both cases9. The validity of these cellular models is also strongly supported by the ability of undifferentiated 3T3-F442A cells10 and Ob17 cells11, after injection into athymic mice, to develop in vivo into unilocular adipocytes. Recent studies, carried out in our laboratory with Ob17 cells, have delineated the status of LPL with respect to i) its development and hormonal regulation during adipose conversion ii) its intracellular process of maturation.
KeywordsLipoprotein Lipase Adipose Cell Lipoprotein Lipase Activity Ob17 Cell Adipose Conversion
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