High extracellular calcium attenuates adipogenesis in 3T3-L1 preadipocytes.
We studied the effect of extracellular Ca(2+) concentration ([Ca(2+)](e)) on adipocyte differentiation. Preadipocytes exposed to continuous [Ca(2+)](e) higher than 2.5 mmol/l accumulated little or no cytoplasmic lipid compared to controls in 1.8 mmol/l [Ca(2+)](e). Differentiation was monitored by Oil Red O staining of cytoplasmic lipid and triglyceride assay of accumulated lipid, by RT-PCR analysis of adipogenic markers, and by the activity of glycerol-3-phosphate dehydrogenase (GPDH). Elevated [Ca(2+)](e) inhibited expression of peroxisome proliferator-activated receptor gamma, CCAAT/enhancer binding protein alpha, and steroid regulatory binding element protein. High [Ca(2+)](e) significantly inhibited differentiation marker expression including adipocyte fatty acid binding protein, and GPDH. The decrease in Pref-1 expression that accompanied differentiation also was prevented by high [Ca(2+)](e). Treatment of 3T3-L1 cells with high [Ca(2+)](e) did not significantly affect cell number or viability and did not trigger apoptosis. Levels of intracellular Ca(+2) remained unchanged in various [Ca(2+)](e). Treatment of 3T3-L1 with pertussis toxin (PTX) partially restored lipid accumulation and increased differentiation markers in cells treated with 5 mmol/l [Ca(2+)](e). 'Classical' parathyroid cell Ca(2+) sensing receptors (CaSR) were not detected either by RT-PCR or by Western blotting. These results suggest that continuous exposure to high [Ca(2+)](e) inhibits preadipocyte differentiation and that this may involve a G-protein-coupled mechanism mediated by a novel Ca(2+) sensor or receptor.
Jensen
Brian
B
Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA.
Farach-Carson
Mary C
MC
Kenaley
Erin
E
Akanbi
Kamil A
KA
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics; D002118:Calcium / Q000494:pharmacology*; D002454:Cell Differentiation; D019070:Cell Lineage; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D050356:Lipid Metabolism; D051379:Mice; D044169:Receptors, Calcium-Sensing / Q000032:analysis; D014157:Transcription Factors / Q000235:genetics
D000943:Antigens, Differentiation; D044169:Receptors, Calcium-Sensing; D014157:Transcription Factors; D002118:Calcium