Cdo binds Abl to promote p38alpha/beta mitogen-activated protein kinase activity and myogenic differentiation.
The p38 mitogen-activated protein kinase (MAPK) pathway is required for differentiation of skeletal myoblasts, but how the pathway is activated during this process is not well understood. One mechanism involves the cell surface receptor Cdo (also known as Cdon), which binds to Bnip-2 and JLP, scaffold proteins for Cdc42 and p38, respectively; formation of these complexes results in Bnip-2/Cdc42-dependent activation of p38. It has been reported that the tyrosine kinase Abl promotes myogenic differentiation in a manner dependent on its cytoplasmic localization, but the cytoplasmic signaling proteins with which it interacts to achieve this effect are unidentified. We report that Abl associates with both Cdo and JLP during myoblast differentiation. Abl binds a proline-rich motif in Cdo via its SH3 domain, and these regions of Abl and Cdo are required for their promyogenic effects. Cdo is important for full Abl kinase activity, and Abl is necessary for full activation of p38 MAPK, during myogenic differentiation. As seen with myoblasts depleted of Cdo, the diminished differentiation displayed by Abl-depleted cells is rescued by the expression of an activated form of the immediate upstream p38-activating kinase MAPK kinase 6. Abl's promyogenic effect is therefore linked to a multiprotein cell surface complex that regulates differentiation-dependent p38 activation.
Bae
Gyu-Un
GU
Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, NY 10029, USA. Robert.Krauss@mssm.edu
Kim
Bok-Geon
BG
Lee
Hye-Jin
HJ
Oh
Ji-Eun
JE
Lee
Su-Jae
SJ
Zhang
Wei
W
Krauss
Robert S
RS
Kang
Jong-Sun
JS
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D002460:Cell Line; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D008856:Microscopy, Fluorescence; D048053:Mitogen-Activated Protein Kinase 6 / Q000235:genetics / Q000378:metabolism; D032446:Myoblasts / Q000166:cytology / Q000378:metabolism*; D011485:Protein Binding; D016315:Proto-Oncogene Proteins c-abl / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection; D020798:Two-Hybrid System Techniques; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; C510744:Cdon protein, mouse; D015815:Cell Adhesion Molecules; D034741:RNA, Small Interfering; C468928:Spag9 protein, mouse; D049452:Green Fluorescent Proteins; D016315:Proto-Oncogene Proteins c-abl; C474633:Mapk6 protein, mouse; D048053:Mitogen-Activated Protein Kinase 6; D048051:p38 Mitogen-Activated Protein Kinases