v-Abl signaling disrupts SOCS-1 function in transformed pre-B cells.
The v-Abl oncogene activates Jak-Stat signaling during transformation of pre-B cells in mice. Disrupting Jak activation by deleting the Jak binding domain of v-Abl or by expressing a dominant-negative Jak1 decreases v-Abl transformation efficiency. As SOCS-1 is a known potent inhibitor of Jak kinases, the mechanism by which v-Abl bypasses SOCS-1 regulation to constitutively activate Jak kinases was investigated. SOCS-1 is expressed in v-Abl-transformed cells but is unable to inhibit v-Abl-mediated Jak-Stat signaling. In v-Abl transformants, SOCS-1 can inhibit cytokine signals, but it is more efficient at doing so when the cells are treated with STI571, an Abl kinase inhibitor. Downstream effects of v-Abl signaling include phosphorylation of SOCS-1 on nontyrosine residues, disruption of the interaction between SOCS-1 and the Elongin BC complex, and inhibition of SOCS-1-mediated proteasomal targeting of activated Jaks. These findings reveal a mechanism by which Jak-dependent oncogenes may bypass SOCS-1 inhibition.
Limnander
André
A
Integrated Program in Cellular, Molecular and Biophysical Studies, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
Danial
Nika N
NN
Rothman
Paul B
PB
D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000378:metabolism / Q000473:pathology; D002352:Carrier Proteins / Q000378:metabolism*; D002471:Cell Transformation, Neoplastic / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D009154:Mutation; D016374:Oncogene Proteins v-abl / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D016374:Oncogene Proteins v-abl; D012097:Repressor Proteins; C108944:SOCS1 protein, human; C491590:Socs1 protein, mouse; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D011505:Protein-Tyrosine Kinases