PI 3-kinase activation in BCR/abl-transformed hematopoietic cells does not require interaction of p85 SH2 domains with p210 BCR/abl
| Autor: | Suresh K. Jain, Marilyn L. Keeler, Nadia Carlesso, Lyuba Varticovski, Brian Druker, Mira Susa |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Recombinant Fusion Proteins
Molecular Sequence Data Immunology Fusion Proteins bcr-abl Biology SH2 domain Biochemistry src Homology Domains Mice Phosphatidylinositol 3-Kinases hemic and lymphatic diseases medicine Animals Humans Amino Acid Sequence Chromatography High Pressure Liquid ABL Kinase breakpoint cluster region 3T3 Cells Cell Biology Hematology Fibroblasts medicine.disease Hematopoietic Stem Cells Cell biology Enzyme Activation Phosphotransferases (Alcohol Group Acceptor) Cancer research Phosphorylation Signal transduction Chronic myelogenous leukemia K562 cells Signal Transduction |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 1528-0020 0006-4971 |
| DOI: | 10.1182/blood.v88.5.1542.bloodjournal8851542 |
| Popis: | BCR/abl is a chimeric oncogene implicated in the pathogenesis of human chronic myelogenous leukemia. Expression of the BCR/abl gene induces hematologic malignancies in transgenic mice and transformation of interleukin-3-dependent hematopoietic cells. The mechanism of BCR/abl- mediated transformation of hematopoietic cells is poorly understood and involves activation of at least two signaling pathways, p21ras and PI 3- kinase. Here we report that PI 3,4-P2 and PI 3,4,5-P3, the enzymatic products of PI 3-kinase, accumulate in metabolically labeled transformed hematopoietic cells, in contrast to our previous report on the lack of accumulation of PI 3-kinase products in nontransformed NIH 3T3 fibroblasts that express p210 BCR/abl. Transformed cells also have increased PI 3-kinase activity in total cell extracts and membrane fractions. Activation of PI 3-kinase occurs by occupancy of SH2 domains of PI 3-kinase regulatory subunit, p85, by phosphorylated YXXM motifs. Therefore, we investigated whether BCR/abl binds to p85 and whether this binding is mediated by interaction of p85 SH2 domains with YXXM motif of BCR/abl. Association of p210 BCR/abl with p85 in immune complexes and with p85 SH2 domains was evident in hematopoietic cells that express the wt p210 BCR/abl. However, the binding of BCR/abl to p85 SH2 domains was abolished in cells expressing mutant, temperature- sensitive (ts) p210 BCR/abl in which the tyrosine in the YXXM motif of p210 BCR/abl was replaced by histidine. Despite lack of direct interaction with p85 SH2 domains, expression of ts p210 BCR/abl resulted in rapid, time-dependent activation of total and membrane- associated PI 3-kinase and increased PI 3-kinase activity in anti-P-tyr and anti-abl immunoprecipitates. These data suggest that BCR/abl- induced activation of PI 3-kinase in hematopoietic cells does not require binding of p85 SH2 domains to BCR/abl gene product and involves interaction with other tyrosine phosphorylated intermediate proteins. |
| Databáze: | OpenAIRE |
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