FUNCTIONAL STAT-1 AND STAT-3 SIGNALING BY THE LEPTIN RECEPTOR (OB-R) - REDUCED EXPRESSION OF THE RAT FATTY LEPTIN RECEPTOR IN TRANSFECTED CELLS

The leptin receptor (OB-R) bears homology to members of the class I cy tokine receptor family. We demonstrate that leptin binding to OB-R sti mulates formation of STAT-1 and STAT-3 complexes, thereby defining tra nscriptional motifs for genes that are under leptin control. Transfect ed fa OB-R bound leptin with equal affinity to that of wild type OB-R. fa OB-R abundance was about 7 fold reduced compared to control cells. Surprisingly, the low level of fa OB-R is fully capable of activating the STAT signal transduction pathway. We discuss plausible explanatio ns for the obese phenotype in Zucker fatty rats.