title: Leptin receptor signal transduction: OBRa and OBRb of fa type.
abstract: We report herein the characterization of activities of signal transduction for three types of leptin receptors (OBRs) from rats, the OBRa, OBRb, and OBRb with fa mutation (OBRb-fa), by measurement of the levels of tyrosine phosphorylation of STAT3 (signal transducers and activators of transcription 3) and MAPK (mitogen-activated protein kinase), which are induced by leptin stimulation of CHO cells stably expressing the OBR (CHO-OBRb, CHO-OBRa, or CHO-OBRb-fa cells). As the result of leptin stimulation, enhanced levels of tyrosine phosphorylation of STAT3 and MAPK were detected in CHO-OBRb cells. In CHO-OBRb-fa cells, enhancement levels for both were lower than those in CHO-OBRb cells. In CHO-OBRa cells, only the phosphorylation of MAPK was detected. These data suggest that these reduced signaling activities cause obesity in fa/fa rats and that OBRa, which has been generally thought to be inactive at signaling, actually transmits signals through the MAPK pathway.
authors.affiliation: Department of Laboratory Medicine, University of Tokushima, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamashita
authors.forename: T
authors.initials: T
authors.lastname: Murakami
authors.forename: S
authors.initials: S
authors.lastname: Otani
authors.forename: M
authors.initials: M
authors.lastname: Kuwajima
authors.forename: K
authors.initials: K
authors.lastname: Shima
mesh_terms: D000818:Animals; D016466:CHO Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002352:Carrier Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D006224:Cricetinae; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D020738:Leptin; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D009154:Mutation; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011956:Receptors, Cell Surface; D018121:Receptors, Cytokine / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D054411:Receptors, Leptin; D011994:Recombinant Proteins / Q000378:metabolism; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D020738:Leptin; D011506:Proteins; D011956:Receptors, Cell Surface; D018121:Receptors, Cytokine; D054411:Receptors, Leptin; D011994:Recombinant Proteins; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D015534:Trans-Activators; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases