Hormonal regulation of malic enzyme and glucose-6-phosphate-dehydrogenase expression in fetal brown-adipocyte primary cultures under non-proliferative conditions.
The expression of malic enzyme and glucose-6-phosphate (Glc6P) dehydrogenase was investigated in primary cultures of fetal brown adipocytes after the prolonged presence (6 d or 10 d) of various hormones under non-proliferative conditions. The presence of triiodothyronine for 6 d and 10 d resulted in maturation of the triiodothyronine regulatory mechanism of malic-enzyme expression at the mRNA level. However, triiodothyronine had no effect on Glc6P dehydrogenase expression. Insulin increased malic-enzyme and Glc6P dehydrogenase expression at the mRNA and protein level after 6 d and 10 d of culture. The joint presence of triiodothyronine and insulin produced an additive effect on malic-enzyme expression at the mRNA and protein level after 6 d and 10 d of culture, by two independent mechanisms. Noradrenaline prevented the effect at the protein level after 6 d, but not after 10 d, probably due to loss of the beta-adrenergic response of brown adipocytes after prolonged culture. Triiodothyronine overexpressed the Glc6P dehydrogenase mRNA induced by the presence of insulin at 6 d and 10 d of culture. There was no adrenergic regulation of Glc6P dehydrogenase expression in cultured fetal brown adipocytes, regardless of the time of culture.
Valverde
A M
AM
Departamento de Bioquìmica y Biologìa Molecular, Facultad de Farmacia, Ciudad Universitaria, Madrid, Spain.
Benito
M
M
Lorenzo
M
M
D002001:Adipose Tissue, Brown / Q000166:cytology / Q000201:enzymology*; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004790:Enzyme Induction; D005954:Glucosephosphate Dehydrogenase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D007328:Insulin / Q000502:physiology*; D008099:Liver / Q000201:enzymology; D008291:Malate Dehydrogenase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D014284:Triiodothyronine / Q000502:physiology*
D007328:Insulin; D012333:RNA, Messenger; D014284:Triiodothyronine; D008291:Malate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D009638:Norepinephrine