Functional analysis of leptin receptor activation using a Janus kinase/signal transducer and activator of transcription complementation assay.
The leptin receptor (LR), a member of the class I cytokine receptor family, is composed of a single subunit. Its extracellular domain consists of two so-called cytokine receptor homology domains, separated by an Ig-like domain, and two additional fibronectin type III modules. Requirements for LR activation were examined using a complementation strategy. Two LR mutants, LR-FFY-Deltabox 1 and LR-F3, deficient in Janus kinase or signal transducer and activator of transcription (STAT) activation, respectively, were only able to generate a STAT3-dependent signal when coexpressed. Based on the requirements for Janus kinase/STAT signaling, and on the lack of complementation with similar receptor constructs, but containing the extracellular domain of the homodimeric erythropoietin receptor, this observation can be explained only by higher order LR clustering. Using a panel of deletion mutants we were able to define a role for the cytokine receptor homology 1 and Ig-like domains in leptin signaling. Moreover, we demonstrate a nonredundant function for the individual receptor chains within the homomeric LR complex. Based on these data, we propose a possible model for LR clustering.
Zabeau
Lennart
L
Flanders Interuniversity Institute for Biotechnology, VIB09, Department of Medical Protein Research, Ghent University, Faculty of Medicine and Health Sciences, Baertsoenkaai 3, B-9000 Ghent, Belgium.
Defeau
Delphine
D
Van der Heyden
José
J
Iserentant
Hannes
H
Vandekerckhove
Joel
J
Tavernier
Jan
J
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D004921:Erythropoietin / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D020738:Leptin / Q000494:pharmacology; D051379:Mice; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D054411:Receptors, Leptin; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D014162:Transfection
D017931:DNA Primers; C515448:LEPR protein, human; D020738:Leptin; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D011994:Recombinant Proteins; C515447:leptin receptor, mouse; D004921:Erythropoietin