Regulation of expression of leptin mRNA and secretion of leptin by thyroid hormone in 3T3-L1 adipocytes.
Leptin, the obese gene product, is secreted exclusively by adipocytes and regulates energy balance. We examined the effects of thyroid hormones on the regulation of leptin in 3T3-L1 adipocytes. Fully differentiated adipocytes were incubated with thyroid hormones, and the expression of leptin mRNA was measured by quantitative reverse transcription-polymerase chain reaction. After a 24-h incubation, triiodothyronine (T3) at 10-1000 nmol/l significantly increased the expression of leptin mRNA (237-337%). These stimulatory effects were not observed in preadipocytes. By contrast, thyroxine (T4) at 1-1000 nmol/l did not affect leptin mRNA expression in adipocytes. We also measured the levels of secreted leptin in conditioned media using radioimmunoassay. T3 at 10 and 1000 nmol/l significantly increased the levels of secreted leptin (132% and 126%, respectively) after a 24-h incubation. Our present data suggest that thyroid hormone is a novel regulator of leptin mRNA expression and protein secretion in 3T3-L1 adipocytes.
Yoshida
T
T
Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan.
Monkawa
T
T
Hayashi
M
M
Saruta
T
T
D016475:3T3 Cells; D000273:Adipose Tissue / Q000187:drug effects* / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D007700:Kinetics; D020738:Leptin; D051379:Mice; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D013963:Thyroid Hormones / Q000494:pharmacology*; D013974:Thyroxine / Q000494:pharmacology; D014284:Triiodothyronine / Q000008:administration & dosage / Q000494:pharmacology
D017931:DNA Primers; D020738:Leptin; D011506:Proteins; D012333:RNA, Messenger; D013963:Thyroid Hormones; D014284:Triiodothyronine; D013974:Thyroxine