Differential Regulation of Long and Short leptin Receptor mRNA by leptin and Dexamethasone in HepG2 Cells

Liu Z-J1, Endoh A2, Li R-S2, Ohzeki T2 

1 The Second Affiliated Hospital Dalian Medical University, Dalian, China

2 Hamamatsu University School of medicine, Hamamatsu, Japan

 

Objective: To study the leptin receptor regulation by leptin and dexamethasone in HepG2 cells.

Methods: By RT-PCR and DNA sequencing, we demonstrated for the first time that long leptin receptor (OB-Rb) and short leptin receptor (OB-Ra) mRNA was expressed in this cell line. Using a quantitative RT-PCR technique, we quantitated the expression of OB-Rb and OB-Ra mRNA at 24 h incubation with various concentrations of leptin (10-9- 10-6 M) or dexamethasone (10-9-10-6 M).

Results: leptin (10-7-10-6M) significantly inhibited the expression of OB-Rb mRNA, with maximum inhibition (to 43% of control) at 10-6 M. Similarly the expression of OB-R219.1 and OB-R219.3, two isoforms of OB-Ra, was also markedly reduced in cells treated with leptin at 10-8- 10-6M, with maximum decrease (to 44% of control at 10-7M for OB-R219.1, and to 49% of control at 10-6M for OB-R219.3). In contrast, dexamethasone (10-8-10-6M) significantly increased the levels of OB-Rb mRNA, with maximum increase (to 204% of control) at 10-7M, and the expression of OB-R219.1 and OB-R219.3 mRNA was also markedly increased at 10-9-10-6M, with maximum increases (to 254% control for OB-R219.1, and to 246% of control for OB-R219.3) at 10-7 M.

Conclusion: leptin down-regulates the expression of OB-Rb and OB-Ra mRNA, and dexamethasone up-regulates the expression of OB-Rb and OB-Ra mRNA in HepG2 cells.

 

 

 
0945