The SH2 domain of P210BCR/ABL is not required for the transformation of hematopoietic factor-dependent cells.
Src-homology region 2 (SH2) domains, by binding to tyrosine-phosphorylated sequences, mediate specific protein-protein interactions important in diverse signal transduction pathways. Previous studies have shown that activated forms of the Abl tyrosine kinase, including P210BCR/ABL of human chronic myelogenous leukemia, require the SH2 domain for the transformation of fibroblasts. To determine whether SH2 is also required for Bcr/Abl to transform hematopoietic cells, we have studied two SH2 domain mutations in P210BCR/ABL: a point mutation in the conserved FLVRES motif (P210/R1033K), which interferes with phosphotyrosine-binding by SH2, and a complete deletion of SH2 (P210/delta SH2). Despite a negative effect on intrinsic Abl kinase activity, both P210 SH2 mutants were still able to transform the hematopoietic factor-dependent cell lines Ba/F3 and FDC-P1 to growth factor independence. Unexpectedly, both mutants showed greater transforming activity than wild-type P210 in a quantitative transformation assay, probably as a consequence of increased stability of the SH2 mutant proteins in vivo. Cells transformed by both P210 SH2 mutants were leukemogenic in synaptic mice and P210/r1053K mice exhibited a distinct disease phenotype, reminiscent of that induced by v-Abl. These results demonstrate that while the Abl SH2 domain is essential for BCR/ABL transformation of fibroblasts, it is dispensable for the transformation of hematopoietic factor-dependent cell lines.
Ilaria
R L
RL
Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA.
Van Etten
R A
RA
D000595:Amino Acid Sequence; D000818:Animals; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D017077:Culture Media, Conditioned / Q000494:pharmacology; D016044:Fusion Proteins, bcr-abl / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology*; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000473:pathology*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010641:Phenotype; D010766:Phosphorylation; D017354:Point Mutation; D011499:Protein Processing, Post-Translational; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D014162:Transfection; D018909:src Homology Domains
D017077:Culture Media, Conditioned; D016298:Hematopoietic Cell Growth Factors; D011993:Recombinant Fusion Proteins; D016044:Fusion Proteins, bcr-abl