Disease relevance of Crk

• In the K562 human chronic myelogenous leukemia cell line, p130cas is not tyrosine phosphorylated or bound to Crk [1].
• Crk is a Src homology 2 (SH2)/Src homology 3 (SH3)-containing adapter protein that has been implicated in intracellular signaling in fibroblasts and PC12 pheochromocytoma cells [2].
• Adaptor molecule Crk is required for sustained phosphorylation of Grb2-associated binder 1 and hepatocyte growth factor-induced cell motility of human synovial sarcoma cell lines [3].
• No Evidence for an Involvement of the P38 and JNK Mitogen-Activated Protein in Inflammatory Bowel Diseases [4].
• The EphB4 receptor suppresses breast cancer cell tumorigenicity through an Abl-Crk pathway [5].

High impact information on Crk

• We show that the migration and early expansion of neural crest cells is unaffected in Crkol-/- embryos [6].
• Here we report that mice homozygous for a targeted null mutation at the CrkL locus (gene symbol Crkol for mice) exhibit defects in multiple cranial and cardiac neural crest derivatives including the cranial ganglia, aortic arch arteries, cardiac outflow tract, thymus, parathyroid glands and craniofacial structures [6].
• This process is independent of PI(3)K, but requires the translocation of Cbl, Crk and C3G to the lipid raft [7].
• The Crk protein contains a single SH2 domain and two SH3 domains in the order SH2-SH3-SH3 [8].
• It has been proposed that the enzymatic activity and substrate recognition of the Src-family kinases, and the protein-binding and transforming activity of Crk-family adaptor proteins, are regulated by intramolecular SH2-pTyr interactions [8].

Chemical compound and disease context of Crk

• We also showed that the recovery from demyelination in cuprizone-treated and aged mice is achieved after administration of the herbal medicine Ninjin'yoeito, an effective therapy targeting the FcRgamma/Fyn-Rho (Rac1)-MAPK (P38 MAPK)-p-MBPs signaling cascade [9].

Biological context of Crk

• Overexpression of the APS/Y(618)F mutant in 3T3-L1 adipocytes blocked the insulin-stimulated tyrosine phosphorylation of endogenous Cbl and binding to Crk [10].
• In vitro analysis showed that this interaction is mediated by the SH2 domain of Crk and can be inhibited with a phosphopeptide containing the Crk-SH2 binding motif [1].
• Instead, Crk proteins predominantly associate with the tyrosine-phosphorylated proto-oncogene product of Cbl [1].
• The product of the cbl oncogene forms stable complexes in vivo with endogenous Crk in a tyrosine phosphorylation-dependent manner [1].
• Crk knockdown by RNA interference disturbed this HGF-induced tyrosine phosphorylation of Gab1 [3].

Anatomical context of Crk

• Crk has been shown to bind to a tyrosine-phosphorylated protein of 116 kDa after TCR-mediated T cell activation [2].
• Interaction between focal adhesion kinase and Crk-associated tyrosine kinase substrate p130Cas [11].
• Our data suggest that v-Crk may be involved in transducing extracellular signals to regulate cytoskeletal organization, and may act on an intrinsic determinant for axonal growth in a variety of neural types including sensory and motor neurons during development [12].
• Previously, in a cellular model for neuronal differentiation, we showed that pheochromocytoma (PC12) cells expressing v-Crk, an oncogenic form of the SH2/SH3-containing c-Crk adaptor protein, potentiates axonal growth and prolongs nerve growth factor (NGF)-independent survival [12].
• In NIH 3T3 cells, IGF-I also stimulated tyrosine phosphorylation of a 45- kDa protein which co-immunoprecipitated with Crk II [13].

Associations of Crk with chemical compounds

• The molecule consists of multiple protein-protein interaction motifs, including a serine-rich region that is positioned between Crk and Src-binding sites [14].
• Simultaneous blocking of ERK and P38 completely abolished the effect of H(2)O(2) on c-Src expression in mouse collecting duct cells [15].
• Expression of a mutant receptor where Tyr900 had been replaced with a phenylalanine residue (Y900F) resulted in a receptor with reduced ability to phosphorylate CrkII [16].
• Requirements for pYXXM motifs in Cbl for binding to the p85 subunit of phosphatidylinositol 3-kinase and Crk, and activation of atypical protein kinase C and glucose transport during insulin action in 3T3/L1 adipocytes [17].
• Phosphotyrosine 900 in the distal kinase domain binds phosphatidylinositol 3-kinase which in turn binds the adaptor protein Crk [18].

Physical interactions of Crk

• DOCK180 is one of the two principal proteins bound to the SH3 domain of the adaptor protein CrkII [19].
• Eps15 and Eps15R bound specifically to the amino-terminal SH3 domain of Crk and coprecipitated equivalently with both c-Crk and v-Crk from cell lysates [20].
• Furthermore, phosphorylation of paxillin by Hck created a binding site for Crk [21].
• Crk complex in response to IGF-I [22].

Enzymatic interactions of Crk

• Crk immunoprecipitates from activated T cell lysates contain tyrosine-phosphorylated Cbl [2].
• The Crk proto-oncogene product is an SH2 and SH3 domain-containing adaptor protein which we have previously shown to become rapidly tyrosine phosphorylated in response to stimulation with insulin-like growth factor I (IGF-I) in NIH-3T3 cells [23].
• We found that DOCK180 was phosphorylated and bound to CrkII in NIH 3T3 cells stimulated with integrin and also in 3Y1 cells transformed by v-src or v-crk [19].
• Moreover, Crk-II mutants lacking in binding to either phosphorylated Cas or DOCK180 suppressed the Y-27632-induced membrane ruffle formation [24].

Co-localisations of Crk

• By immunofluorescence microscopy we have determined that c-Cbl co-localizes with the adaptor protein Crk to submembranous actin lamellae in NIH 3T3 fibroblasts and that c-Cbl's actin localization requires specific SH3-binding sequences [25].

Regulatory relationships of Crk

• IGF-I stimulated tyrosine phosphorylation of Crk II in a dose- and time-dependent manner [13].
• P38 does not seem to have a direct role in leading to oxidant-induced NF-kappaB translocation but may affect other oxidant-induced transcription factors [26].
• Both morphine and TGF-beta promoted P38 mitogen-activated protein kinase (MAPK) phosphorylation, and this phosphorylation was inhibited by SB 202190 as well as by SB 203580 [27].
• In a reconstitution experiment, expression of DOCK180 induced hyperphosphorylation of p130(Cas) and a concomitant increase in the amount of CrkII bound to p130(Cas) [19].
• The overexpression of a CAP mutant in which the SoHo domain had been deleted (CAPDeltaSoHo) prevented the translocation of Cbl to lipid rafts and subsequently blocked the recruitment of CrkII and C3G [28].

Other interactions of Crk

• Like c-Cbl, Cbl-b associates constitutively with CAP and interacts with Crk upon insulin stimulation [29].
• Here we identify CrkII, CrkL and Dock1 in complexes bound to tyrosine-phosphorylated Dab1, through mass spectrometry [30].
• Overexpression of CrkIIGFP rescued the migration of these cells, suggesting that Dab1 makes Crk a limiting factor for migration [30].
• Regulation of Crk/CrkL, C3G, and Rap1 by Reelin may be involved in coordinating neuron migrations during brain development [31].
• We have explored the role of endogenous Crk proteins in Bcr-Abl-transformed cells [1].

Analytical, diagnostic and therapeutic context of Crk

• We have demonstrated the existence of native CrkIII at the message level using RT-PCR and RNAse protection assays, and at the protein level in mouse fibroblasts [32].
• In Northern blot analysis, the mouse c-crk mRNA is expressed ubiquitously in every tissue and organ, suggesting that the c-Crk protein may be a common signal transducing molecule among tissues [33].
• The insulin-induced decrease in the CrkII-p130(cas) association was further confirmed by Far Western Blot analysis with the Src homology 2 (SH2) domain of CrkII [34].
• P44/P42 and P38 MAPK activation were evaluated by Western blot assays with anti-phospho MAPK antibodies [35].
• Although the function of Crk has been studied in considerable detail in cell culture, its biological role in vivo is still unclear, and no Crk-knockout mouse model has been available [36].

References