Rise in cytosolic Ca2+ abolishes in preadipose cells the expression of lipoprotein lipase stimulated by growth hormone.
Lipoprotein lipase (LPL) is known to be an early marker of adipose cell differentiation. Growth hormone (GH) stimulates in preadipose Ob1771 cells the expression of LPL gene and this effect is mediated at least in part by c-fos protooncogene, the expression of which is transiently activated by a protein kinase C-dependent pathway (Barcellini-Couget et al., Endocrinology, 1993, 132: 55-60). Since GH stimulates the formation of diacylglycerol from phosphatidylcholine independently of Ca2+ mobilization, the role of Ca2+ was studied in regard to LPL gene expression stimulated by GH. The results obtained in the presence of Ca2+ ionophores show that a rise in intracellular free Ca2+ abolishes this expression but has no effect on the expression of various adipose-related genes, including the transient expression of c-fos protooncogene. Therefore, the inability of preadipose cells to mobilize Ca2+ in response to GH, at an early stage of the differentiation process, appears as a prerequisite for the maximal expression of LPL.
Barcellini-Couget
S
S
Centre de Biochimie (UMR 134 CNRS), Université de Nice-Sophia Antipolis, Faculté des Sciences, Parc Valrose, France.
Vassaux
G
G
Negrel
R
R
Ailhaud
G
G
D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002454:Cell Differentiation; D002460:Cell Line; D015870:Gene Expression / Q000187:drug effects; D016762:Genes, fos; D013006:Growth Hormone / Q000494:pharmacology*; D066298:In Vitro Techniques; D015759:Ionomycin / Q000494:pharmacology; D008071:Lipoprotein Lipase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics
D012333:RNA, Messenger; D000001:Calcimycin; D015759:Ionomycin; D013006:Growth Hormone; D008071:Lipoprotein Lipase; D002118:Calcium