Localization of BCR-ABL to F-actin regulates cell adhesion but does not attenuate CML development

• Published in: Blood 2003-09, Vol.102 (6), p.2220-2228
• Main Authors: Wertheim, Jason A., Perera, Samanthi A., Hammer, Daniel A., Ren, Ruibao, Boettiger, David, Pear, Warren S.
• Format: Article
• Language: English
• Subjects: Actins - metabolism; Animals; Biological and medical sciences; Bone Marrow Cells - metabolism; Bone Marrow Cells - pathology; Bone Marrow Transplantation; Cell Adhesion - physiology; Fibronectins - metabolism; Fusion Proteins, bcr-abl - chemistry; Fusion Proteins, bcr-abl - genetics; Fusion Proteins, bcr-abl - metabolism; Hematologic and hematopoietic diseases; Integrin alpha4beta1 - metabolism; Integrin alpha5beta1 - metabolism; Leukemia, Myelogenous, Chronic, BCR-ABL Positive - metabolism; Leukemia, Myelogenous, Chronic, BCR-ABL Positive - pathology; Leukemia, Myelogenous, Chronic, BCR-ABL Positive - physiopathology; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Medical sciences; Mice; Mice, Inbred C57BL; Protein Binding - physiology; Protein Structure, Tertiary
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2003-01-0062

We have previously found that P210BCR-ABL increases the adhesion of hematopoietic cell lines to fibronectin by a mechanism that is independent of tyrosine kinase activity. To investigate the pathway(s) by which P210BCR-ABL influences cell adhesion, we used a quantitative cell adhesion device that can discern small changes in cell adhesion to assay P210BCR-ABL with mutations in several critical domains. We expressed P210BCR-ABL mutants in 32D myeloblast cells and found that binding to fibronectin is mediated primarily by the α5β1 integrin. We performed a structure/function analysis to map domains important for cell adhesion. Increased adhesion was mediated by 3 domains: (1) the N-terminal coiled-coil domain that facilitates oligomerization and F-actin localization; (2) bcr sequences between aa 163 to 210; and (3) F-actin localization through the C-terminal actin-binding domain of c-abl. We compared our adhesion results with the ability of these mutants to cause a chronic myelogenous leukemia (CML)–like disease in a murine bone marrow transplantation assay and found that adhesion to fibronectin did not correlate with the ability of these mutants to cause CML. Together, our results suggest that F-actin localization may play a pivotal role in modulating adhesion but that it is dispensable for the development of CML.