Localization of BCR-ABL to F-actin regulates cell adhesion but does not attenuate CML development.
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 alpha5beta1 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.
Wertheim
Jason A
JA
Department of Pathology and Laboratory Medicine, University of Pennsylvania, 611 BRB II/III, 421 Curie Blvd, Philadelphia, PA 19104-6160.
Perera
Samanthi A
SA
Hammer
Daniel A
DA
Ren
Ruibao
R
Boettiger
David
D
Pear
Warren S
WS
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism / Q000473:pathology; D016026:Bone Marrow Transplantation; D002448:Cell Adhesion / Q000502:physiology; D005353:Fibronectins / Q000378:metabolism; D016044:Fusion Proteins, bcr-abl / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D039041:Integrin alpha4beta1 / Q000378:metabolism; D039081:Integrin alpha5beta1 / Q000378:metabolism; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary
D000199:Actins; D005353:Fibronectins; D039041:Integrin alpha4beta1; D039081:Integrin alpha5beta1; D016044:Fusion Proteins, bcr-abl