title: Leptin activates AMP-activated protein kinase in hepatic cells via a JAK2-dependent pathway.
abstract: AMP-activated protein kinase (AMPK) plays a key role in the regulation of energy homeostasis within the individual cell. Recent reports have suggested that leptin, an adipocyte-secreted hormone, phosphorylates AMPK in skeletal muscle directly. However, little is known about the interaction between leptin signaling and AMPK activation. Here, we report that the leptin-induced phosphorylation of AMPK was detected in Huh7 cells expressing long form leptin receptor (OBRb) as well as short form leptin receptor (OBRa). In addition, we demonstrate that AMPK activation does not require the phosphorylation of either Tyr-985 or Tyr-1138 within the OBRb and may occur via a STAT3-independent signaling pathway. We also show that Huh7 cells expressing OBRb and SOCS3 (inhibitor of JAK2) resulted in a marked reduction of AMPK activation in response to leptin. These findings suggest that the activation of JAK2, but not STAT3, may play a critical role in leptin-induced AMPK activation in Huh7 cells.
authors.affiliation: Graduate School of Human Health Science, Siebold University of Nagasaki, 1-1-1 Manabino, Nagayo, Nagasaki 852-2195, Japan. uotani@sun.ac.jp
authors.forename: Shigeo
authors.initials: S
authors.lastname: Uotani
authors.forename: Takahiro
authors.initials: T
authors.lastname: Abe
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Yamaguchi
mesh_terms: D055372:AMP-Activated Protein Kinases; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D053614:Janus Kinase 2 / Q000378:metabolism*; D020738:Leptin / Q000494:pharmacology*; D009097:Multienzyme Complexes / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D054411:Receptors, Leptin; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
chemical_list: C515448:LEPR protein, human; D020738:Leptin; D009097:Multienzyme Complexes; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases