Nck, a melanoma cDNA encoding a cytoplasmic protein consisting of the src homology units SH2 and SH3

Institute for Immunology, Munich, FRG.
Nucleic Acids Research (Impact Factor: 9.11). 03/1990; 18(4):1048. DOI: 10.1093/nar/18.4.1048
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Available from: Judith P Johnson
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    • "Two highly conserved members of the cytosolic adaptor protein Nck (non-catalytic region of tyrosine kinase) are found in humans: Nck1/Nckα and Nck2/Nckβ (also known as Grb4) [5,6]. These two proteins have a 68% similarity when the amino acid sequences are compared [7]. "
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    ABSTRACT: Signalling by the T cell antigen receptor (TCR) results in the activation of T lymphocytes. Nck1 and Nck2 are two highly related adaptor proteins downstream of the TCR that each contains three SH3 and one SH2 domains. Their individual functions and the roles of their SH3 domains in human T cells remain mostly unknown. Using specific shRNA we down-regulated the expression of Nck1 or Nck2 to approximately 10% each in Jurkat T cells. We found that down-regulation of Nck1 impaired TCR-induced phosphorylation of the kinases Erk and MEK, activation of the AP-1 and NFAT transcription factors and subsequently, IL-2 and CD69 expression. In sharp contrast, down-regulation of Nck2 hardly impacts these activation read-outs. Thus, in contrast to Nck2, Nck1 is a positive regulator for TCR-induced stimulation of the Erk pathway. Mutation of the third SH3 domain of Nck1 showed that this domain was required for this activity. Further, TCR-induced NFAT activity was reduced in both Nck1 and Nck2 knock-down cells, showing that both isoforms are involved in NFAT activation. Lastly, we show that neither Nck isoform is upstream of p38 phosphorylation or Ca2+ influx. In conclusion, Nck1 and Nck2 have non-redundant roles in human T cell activation in contrast to murine T cells.
    Full-text · Article · Mar 2014 · Cell Communication and Signaling
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    • "Similar to other members of this family, NCK has been shown to couple signals from activated receptor tyrosine kinases to downstream effectors through its various SH domains [11]. In mammals there are two isoforms of NCK, NCK1 and NCK2, which share 68% amino acid identity and have been considered functionally redundant [12-14]. NCK is predominantly cytoplasmic but, unexpectedly, continually shuttles in and out of the nucleus, as determined by the nuclear accumulation of NCK in cells treated with leptomycin B [15]. "
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    ABSTRACT: The cellular response to DNA damage requires the coordination of many proteins involved in diverse molecular processes. Discrete molecular pathways are becoming increasingly well understood, but the interconnectivity and coordination of multiple pathways remains less clear. We now show that NCK, an adapter protein involved in cytoskeletal responses to tyrosine kinase receptor signaling, accumulates in the nucleus in response to DNA damage and this translocation can be blocked by specific inhibition of the ATR protein kinase. Strikingly, HeLa cells depleted of NCK undergo apoptosis shortly after UV irradiation, as monitored by caspase-3 cleavage and PARP cleavage. This rapid, hyperactive apoptosis in NCK depleted cells might be p53 dependent, because loss of NCK also increased UV-induced p53 phosphorylation. Importantly, depletion of SOCS7, which is necessary for NCK nuclear translocation, phenocopies NCK depletion, indicating the nuclear accumulation of NCK is responsible for these molecular events. There are two NCK isoforms that have mostly redundant functions, and although NCK2 appears to have a greater contribution, depletion of NCK1 or NCK2, led to increased p53 phosphorylation and early apoptosis after UV exposure. These data reveal a novel function for NCK in regulating p53 phosphorylation and apoptosis, and provide evidence for interconnectedness of growth factor signaling proteins and the DNA damage response.
    Preview · Article · Sep 2013 · PLoS ONE
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    • "Originally the Nck1 cDNA was isolated from a human melanoma cDNA expression library using a monoclonal antibody produced against the human melanoma-associated antigen [5], which has no similarity with Nck1. This suggests that the Nck1 mRNA might be abundant in human melanoma. "
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    ABSTRACT: Nck1 and Nck2 adaptor proteins are involved in signaling pathways mediating proliferation, cytoskeleton organization and integrated stress response. Overexpression of Nck1 in fibroblasts has been shown to be oncogenic. Through the years this concept has been challenged and the consensus is now that overexpression of either Nck cooperates with strong oncogenes to transform cells. Therefore, variations in Nck expression levels in transformed cells could endorse cancer progression. Expression of Nck1 and Nck2 proteins in various cancer cell lines at different stages of progression were analyzed by western blots. We created human primary melanoma cell lines overexpressing GFP-Nck2 and investigated their ability to proliferate along with metastatic characteristics such as migration and invasion. By western blot analysis, we compared levels of proteins phosphorylated on tyrosine as well as cadherins and integrins in human melanoma cells overexpressing or not Nck2. Finally, in mice we assessed tumor growth rate of human melanoma cells expressing increasing levels of Nck2. We found that expression of Nck2 is consistently increased in various metastatic cancer cell lines compared with primary counterparts. Particularly, we observed significant higher levels of Nck2 protein and mRNA, as opposed to no change in Nck1, in human metastatic melanoma cell lines compared with non-metastatic melanoma and normal melanocytes. We demonstrated the involvement of Nck2 in proliferation, migration and invasion in human melanoma cells. Moreover, we discovered that Nck2 overexpression in human primary melanoma cells correlates with higher levels of proteins phosphorylated on tyrosine residues, assembly of Nck2-dependent pY-proteins-containing molecular complexes and downregulation of cadherins and integrins. Importantly, we uncovered that injection of Nck2-overexpressing human primary melanoma cells into mice increases melanoma-derived tumor growth rate. Collectively, our data indicate that Nck2 effectively influences human melanoma phenotype progression. At the molecular level, we propose that Nck2 in human primary melanoma promotes the formation of molecular complexes regulating proliferation and actin cytoskeleton dynamics by modulating kinases or phosphatases activities that results in increased levels of proteins phosphorylated on tyrosine residues. This study provides new insights regarding cancer progression that could impact on the therapeutic strategies targeting cancer.
    Full-text · Article · Oct 2011 · BMC Cancer
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