The BCR/ABL oncogene alters interaction of the adapter proteins CRKL and CRK with cellular proteins.
The Philadelphia chromosome translocation generates a chimeric oncogene, BCR/ABL, which causes chronic myelogenous leukemia (CML). In primary leukemic neutrophils from patients with CML, the major tyrosine phosphorylated protein is CRKL, an SH2-SH3-SH3 adapter protein which has an overall homology of 60% to CRK, the human homologue of the v-crk oncogene. In cell lines transformed by BCR/ABL, CRKL was tyrosine phosphorylated, while CRK was not. We looked for changes in CRK- and CRKL-binding proteins in Ba/F3 hematopoietic cell lines which were transformed by BCR/ABL. Anti-CRK II or anti-CRKL immunoprecipitates were probed by far Western blotting with CRK II- or CRKL-GST fusion proteins to display CRK- and CRKL-coprecipitating proteins. There was a striking qualitative difference in the proteins coprecipitating with CRKL and CRK II. In untransformed cells, three major proteins coprecipitated with CRKL, identified as C3G, SOS and c-ABL. Each of these proteins was found to interact with the CRKL-SH3 domains, but not the SH2 domain. After BCR/ABL transformation, the CRKL SH3-domain binding proteins did not change, with the exception that BCR/ABL now coprecipitated with CRKL. Compared to CRKL, very few proteins coprecipitated with CRK II in untransformed, quiescent cells. After BCR/ABL transformation, both the CRKL- and CRK-SH2 domains bound to a new complex of proteins of approximate molecular weight 105-120 kDa. The major protein in this complex was identified as p120CBL. Thus, in these hematopoietic cell lines, CRKL is involved to a greater extent than CRK II in normal signaling pathways that involve c-ABL, C3G and SOS. In BCR/ABL-transformed cells, CRKL but not CRK II, appears to form complexes which potentially link BCR/ABL, c-ABL, C3G, and SOS to the protooncoprotein, p120CBL.
Uemura
N
N
Division of Hematologic Malignancies, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02115, USA.
Salgia
R
R
Li
J L
JL
Pisick
E
E
Sattler
M
M
Griffin
J D
JD
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D002461:Cell Line, Transformed; D016044:Fusion Proteins, bcr-abl / Q000235:genetics*; D016313:Genes, abl; D006412:Hematopoietic Stem Cells / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism*; D011233:Precipitin Tests; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D050737:Proto-Oncogene Proteins c-crk; D020664:Son of Sevenless Proteins; D044767:Ubiquitin-Protein Ligases; D018909:src Homology Domains / Q000502:physiology
D048868:Adaptor Proteins, Signal Transducing; D000911:Antibodies, Monoclonal; C082869:CRKL protein; D008565:Membrane Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D050737:Proto-Oncogene Proteins c-crk; D020664:Son of Sevenless Proteins; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D016044:Fusion Proteins, bcr-abl; C067419:CBL protein, human; C493849:Cbl protein, mouse