[Effects of leptin and insulin on leptin receptors mRNA expression in human hepatocellular HepG2 cells].
OBJECTIVE
To study the leptin receptor isoforms regulation by leptin and insulin.


METHODS
Human hepatocellular carcinoma cells of the line HepG2 were cultured in DMEM containing 10% FBS in six-well plate and were incubated for 24 hours in serum-free medium containing 0, 10(-9), 10(-8), 10(-7), and 10(-6) mol/L of human leptin or insulin. Using the semi-quantitative RT-PCR technique, the mRNA expressions of long (OB-Rb) and short (OB-Ra: OB-R219.3) leptin receptor isoforms were measured.


RESULTS
OB-Rb and OB-R219.3 mRNAs were expressed in this cell line. Leptin of the concentrations of 10(-7) approximately 10(-6) mol/L significantly inhibited the OB-Rb mRNA expression, with the maximum decrease (by 43%) at the concentration of 10(-6) mol/L. Similarly the mRNA expression of OB-R219.3 was also markedly reduced in cells treated with leptin of the concentrations of 10(-8) approximately 10(-6) (mol/L), with the maximum inhibition (by 49%) at the concentrations of 10(-6) mol/L. Insulin showed no effect on OB-Rb and OB-R219.3 mRNAs expression in HepG2 cell.


CONCLUSIONS
In HepG2 cells, leptin down-regulates the expressions of OB-Rb and OB-R219.3 mRNAs, and insulin has no effect on OB-Rb and OB-R219.3 mRNAs, which contributes at least partly to an understanding of the mechanism of leptin resistance in vivo and suggests that leptin-induced receptor down-regulation may be relevant to leptin resistance at sites of peripheral action.
Liu
Zheng-Juan
ZJ
Department of Pediatrics, 2nd Hospital of Chinese Medical University, Shenyang 110004, China.
Yao
Xing-Jia
XJ
Wang
Yu-Chuan
YC
Wang
De-Ying
DY
Chen
Zhu-Ming
ZM
Zhai
Ling-Ling
LL
D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D020738:Leptin / Q000494:pharmacology*; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000235:genetics; D054411:Receptors, Leptin; D014407:Tumor Cells, Cultured
D007328:Insulin; C515448:LEPR protein, human; D020738:Leptin; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin