p130CAS Forms a Signaling Complex with the Adapter Protein CRKL in Hematopoietic Cells Transformed by the BCR/ABL Oncogene

Abstract

The Philadelphia chromosome (Ph) translocation generates a chimeric tyrosine kinase oncogene, BCR/ABL, which causes chronic myelogenous leukemia (CML) and a type of acute lymphoblastic leukemia (ALL). In primary samples from virtually all patients with CML or Ph ؉ ALL, the CRKL adapter protein is tyrosine phosphorylated and physically associated with p210 BCR/ABL . CRKL has one SH2 domain and two SH3 domains and is structurally related to c-CRK-II (CRK) and the v-Crk oncoprotein. We have previously shown that CRKL, but not the related adapter protein c-CRK, is tyrosine phosphorylated in cell lines transformed by BCR/ABL, and that CRKL binds to BCR/ABL through the CRKL-SH3 domains. Furthermore, the CRKL-SH2 domain has been shown to bind one or more cellular proteins, one of which is p120CBL . Here we demonstrate that another cellular protein linked to BCR/ABL through the CRKL-SH2 domain is p130 CAS . p130 CAS was found to be tyrosine phosphorylated and associated with CRKL in BCR/ABL expressing cell lines and in samples obtained from CML and ALL patients, but not in samples from controls. In both normal and BCR/ABL transformed cells, p130 CAS was detected in focal adhesion-like structures, as was BCR/ABL. In normal cells, the focal adhesion proteins tensin, p125 FAK , and paxillin constitutively associated with p130 CAS . However, in BCR/ABL transformed cells, the interaction between p130 CAS and tensin was disrupted, while the associations between p130 CAS , p125 FAK , and paxillin were unaffected. These results suggest that the BCR/ABL oncogene could alter the function of p130 CAS in at least three ways: tyrosine phosphorylation, inducing constitutive binding of CRKL to a domain in p130 CAS containing Tyr-X-X-Pro motifs (substrate domain), and disrupting the normal interaction of p130 CAS with the focal adhesion protein tensin. These alterations in the structure of signaling proteins in focal adhesion like structures could contribute to the known adhesion abnormalities in CML cells.

Transmembrane tyrosine phosphatase LAR induces apoptosis by dephosphorylating and destabilizing p130Cas

“…p130 Cas is a substrate of several tyrosine kinases including Src (Hamasaki et al 1996), p125 FAK (Polte & Hanks 1995;Cary et al 1998) and Fyn . Functionally, p130 Cas has been shown to be involved in cell transformation Nojima et al 1996;Salgia et al 1996), cell adhesion (Nojima et al 1996;Vuori et al 1996;Nakamoto et al 1997), actin organization (Nakamura et al 1998) and cell migration (Cary et al 1998;Klemke et al 1998). Taken together, these results suggest that p130 Cas is a multifunctional protein which is involved in many aspects of cellular physiology and can be regulated by a variety of stimuli.…”

Role of the adapter protein CRKL in signal transduction of normal hematopoietic and BCR/ABL-transformed cells

“…58 Also, the SH2 domain of CRKL has been found to bind to HEF1, or CAS. 28,30 It has been shown that the CRK-SH2 domain can intramolecularly bind to the tyrosine at position 221(Y 221 XXP). 9,59 Similarly, it has been hypothesized that the CRKL- …”

“…Similar to normal cell signaling, the CRKL SH2 domain binds to CAS family proteins 28 and CBL, 22,26 and the interaction of the known SH3 binding proteins C3G, SOS and ABL does not change upon BCR/ABL transformation. 20 The contri-bution of CRKL to transformation is independent from GRB2, however, the exact mechanism is unknown.…”

“…81 BCR/ABL-transformed cells have an altered F-actin structure and have tyrosine phosphorylation of focal adhesion proteins such as tensin, talin, vinculin, RAFTK, p125 FAK , and paxillin. 28,33,86 CRKL is the key signaling molecule which links BCR/ABL to the focal adhesion protein paxillin. 33 Paxillin is a 68 kDa multi-functional protein with three YXXP motifs at the N-terminus and four LIM domains at the C-terminus.…”

“…CRKL associates with CAS and paxillin in BCR/ABL-transformed cells and therefore has the potential role to recruit BCR/ABL to the cytoskeleton. 28 This physical interaction with BCR/ABL mediated through CRKL could contribute to the known defects associated with the cytoskeleton in CML cells.…”