title: Identification of a novel function of the clathrin-coated structure at the plasma membrane in facilitating GM-CSF receptor-mediated activation of JAK2.
abstract: It is well known that ligand binding to the high-affinity GM-CSF receptor (GMR) activates JAK2. However, how and where this event occurs in a cellular environment remains unclear. Here, we demonstrate that clathrin- but not lipid raft-mediated endocytosis is crucial for GMR signaling. Knockdown expression of clathrin heavy chain or intersectin 2 (ITSN2) attenuated GMR-mediated activation of JAK2, whereas inhibiting clathrin-coated pits or plagues to bud off the membrane by the dominant-negative mutant of dynamin enhanced such event. Moreover, unlike the wild-type receptor, an ITSN2-non-binding mutant of GMR defective in targeting to clathrin-coated pits or plagues [collectively referred to as clathrin-coated structures (CCSs) here] failed to activate JAK2 at such locations. Additional experiments demonstrate that ligand treatment not only enhanced JAK2/GMR association at CCSs, but also induced a conformational change of JAK2 which is required for JAK2 to be activated by CCS-localized CK2. Interestingly, ligand-independent activation of the oncogenic mutant of JAK2 (JAK2V617F) also requires the targeting of this mutant to CCSs. But JAK2V617F seems to be constitutively in an open conformation for CK2 activation. Together, this study reveals a novel functional role of CCSs in GMR signaling and the oncogenesis of JAK2V617F.
authors.affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Ping-Hung
authors.initials: PH
authors.lastname: Chen
authors.forename: Fan-Ching
authors.initials: FC
authors.lastname: Chien
authors.forename: Sue-Ping
authors.initials: SP
authors.lastname: Lee
authors.forename: Woan-Eng
authors.initials: WE
authors.lastname: Chan
authors.forename: I-Hsuan
authors.initials: IH
authors.lastname: Lin
authors.forename: Chun-Shan
authors.initials: CS
authors.lastname: Liu
authors.forename: Fang-Jen
authors.initials: FJ
authors.lastname: Lee
authors.forename: Jiann-Shiun
authors.initials: JS
authors.lastname: Lai
authors.forename: Peilin
authors.initials: P
authors.lastname: Chen
authors.forename: Hsin-Fang
authors.initials: HF
authors.lastname: Yang-Yen
authors.forename: Jeffrey Jong-Young
authors.initials: JJ
authors.lastname: Yen
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002966:Clathrin / Q000378:metabolism*; D003034:Coated Pits, Cell-Membrane / Q000378:metabolism*; D004705:Endocytosis; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D053614:Janus Kinase 2 / Q000378:metabolism*; D008024:Ligands; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D011487:Protein Conformation; D021381:Protein Transport; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D002966:Clathrin; D008024:Ligands; D050505:Mutant Proteins; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; C115919:intersectin 1; D053614:Janus Kinase 2