Disease relevance of GRB2

• We have used liposomes to deliver nuclease-resistant antisense oligodeoxynucleotides (oligos) specific for the GRB2 mRNA to breast cancer cells [1].
• Interestingly, when the phage display peptides were then phosphorylated on tyrosine, their affinity for GRB2 increased dramatically [2].
• IRS1 and GRB2 as members of the IGF signal transduction pathway are not associated with intrauterine growth retardation and Silver-Russell syndrome [3].
• We have identified several bands in glial and medulloblastoma tumours that are recognized by Grb2 but these did not correspond to any known protein [4].
• Taken together, this study indicates that Grb3-3 is a cellular factor that can be up-regulated by HIV-1 [5].

Psychiatry related information on GRB2

• We found that proteins implicated in signal transduction from cell surface receptors via the ras pathway, namely Grb2 and SOS-1, were altered in cases of Alzheimer's disease in comparison to age-matched controls [6].

High impact information on GRB2

• Here we report the cloning of the cDNA for a highly tyrosine-phosphorylated 36-38 kDa protein, previously characterized by its association with Grb2, phospholipase C-gamma1, and the p85 subunit of phosphoinositide 3-kinase [7].
• We demonstrate that BCR-ABL exists in a complex with GRB-2 in vivo [8].
• The SH2/SH3 domain-containing GRB-2 protein links tyrosine kinases to Ras signaling [8].
• Immunoblotting experiments indicate that GRB2 associates with tyrosine-phosphorylated epidermal growth factor receptors (EGFRs) and platelet-derived growth factor receptors (PDGFRs) via its SH2 domain [9].
• It also binds SHP-1 and Grb2 in vitro and has negative regulatory effects on cellular responses induced by growth factors, oncogenes or insulin [10].

Chemical compound and disease context of GRB2

• Finally, we also found that Grb3-3 potentiates HIV-1 long terminal (LTR) repeat promoter activity following T-cell receptor stimulation, an effect that can be largely suppressed by cyclosporin A [5].
• Decreased mitogenic response to epidermal growth factor in human squamous cell carcinoma lines overexpressing epidermal growth factor receptor owing to limiting amounts of the adaptor protein Grb2: rescue by retinoic acid treatment [11].
• We have identified adenosine deaminase, an enzyme involved in purine metabolism whose deficiency is associated with severe combined immunodeficiency, as a Grb3-3 binding protein that is not able to bind to Grb2 [12].
• Expression of Nck, c-Crk, Grb2/Ash, phosphoinositide (PI) 3-kinase p110 alpha and Werner's syndrome gene product WRN was noticeably reduced in late passage cells, showing a concurrent downregulation of a set of signaling molecules accompanying aging [13].
• Biological assays on G1TE(Gla(2-)) in which the original residue of Glu(2-) was substituted by gamma-carboxyglutamic acid (Gla) indicated that it could inhibit the interaction between activated GF receptor and Grb2 protein in cell homogenates of MDA-MB-453 breast cancer cells at the 2 microM level [14].

Biological context of GRB2

• Integrin-mediated signal transduction linked to Ras pathway by GRB2 binding to focal adhesion kinase [15].
• Biochemical studies with the SH2(N+C) mutant showed that it also blocked early TCR signaling events, such as p95vav tyrosine phosphorylation, extracellular signal-regulated kinase 2 activation, and the association of a number of tyrosine-phosphorylated proteins with growth factor receptor-binding protein 2 (GRB2) [16].
• The sequence on the C-terminal side of Tyr789 (YANF) fits the consensus binding site for the SH3-SH2-SH3 adaptor protein GRB2 (YXNX) [17].
• Analysis of in vitro binding kinetics coupled with results from transient co-transfections demonstrated that RPTPalpha is tightly bound to GRB2 [18].
• Previous studies have demonstrated that GRB2 directly interacts with Shc, a proto-oncogene product that is tyrosine phosphorylated upon receptor and nonreceptor PTK activation [19].

Anatomical context of GRB2

• Implication of the GRB2-associated phosphoprotein SLP-76 in T cell receptor-mediated interleukin 2 production [20].
• This is the first demonstration of a growth factor- or cytokine-induced coupling of a protein through an SH3 domain and suggests that GRB2 functions to target PTP1D, in addition to Sos, to the plasma membrane in response to EGF [21].
• Stimulation of smooth muscle cells with angiotensin II resulted in tyrosine phosphorylation on Shc proteins and subsequent complex formation between Shc and growth factor receptor binding protein-2 (GRB2) [22].
• We assigned GRB2 to human chromosome 17 by hybridization to a somatic cell hybrid mapping panel [23].
• Regulation of GRB2 and FLICE2 expression by TNF-alpha in rheumatoid synovium [24].

Associations of GRB2 with chemical compounds

• These results suggest that the coupling of receptor tyrosine kinases to Ras signaling is mediated by a molecular complex consisting of GRB2 and hSos1 [25].
• Human Sos1: a guanine nucleotide exchange factor for Ras that binds to GRB2 [25].
• Within the leucine-rich repeats of both SOC-2 and SHOC-2 are two YXNX motifs that are potential tyrosine-phosphorylated docking sites for the SEM-5/GRB2 Src homology 2 domain [26].
• GRB2 and phospholipase C-gamma 1 associate with a 36- to 38-kilodalton phosphotyrosine protein after T-cell receptor stimulation [19].
• We cloned and expressed the SH2 domain of human GRB2 as glutathione S-transferase and maltose binding protein fusion proteins [2].

Physical interactions of GRB2

• PI 3-kinase and GRB-2 bind to the CD28 phosphotyrosine-based Tyr-Met-Asn-Met motif by means of intrinsic Src-homology 2 (SH2) domains [27].
• Cdc42 and Grb2 bind simultaneously to N-WASp and enhance actin polymerization synergistically [28].
• In these cells, CBLB constitutively binds the GRB2 adaptor predominantly through its N-terminal SH3 domain, to form a complex that is distinct from the GRB2.CBL and GRB2.SOS1 complexes [29].
• Finally, the PKAI-EGF-R association occurs through the binding of RIalpha to the SH3 domain(s) of Grb2 adaptor protein, thus allowing the recruitment of the PKAI holoenzyme to the activated EGF-R [30].
• The Grb2 SH3(C) binding region of Gab1 has significant homology to a region of the adapter protein SLP-76 [31].

Enzymatic interactions of GRB2

• Therefore, we conclude that the physical association of SHPTP2 with the phosphorylated betac receptor and Grb2 and its early activation are required for the coupling of the receptor to the Ras signaling pathway and for prevention of eosinophil death by IL-5 [32].
• Combined cell lysates were affinity-purified over the SH2 domain of the adapter protein Grb2 (GST-SH2 fusion protein) that specifically binds phosphorylated EGFR and Src homologous and collagen (Shc) protein [33].
• A constitutive complex of Grb2 and Cbl could be recruited to both receptor isoforms via docking of Shc to phosphorylated Tyr-1062 in RET [34].
• Enzyme-linked immunosorbent assays confirmed the interaction between the SH2 domain of Grb2 and a tyrosine-phosphorylated MAP-2 peptide spanning the pY(67)SN motif [35].
• Grb2 binding is mediated through a phosphorylated tyrosine residue (Y177) located within a consensus Grb2 binding site encoded by the first exon of the BCR gene [36].

Regulatory relationships of GRB2

• These results suggest that Grb2 may activate Arp2/3 complex-mediated actin polymerization downstream from the receptor tyrosine kinase signaling pathway [28].
• The RIalpha subunit of protein kinase A (PKA) binds to Grb2 and allows PKA interaction with the activated EGF-receptor [30].
• As in the case of PI3-kinase, antibody-induced cross-linking of CD28 induces a time-dependent recruitment of GRB-2 [37].
• In contrast to insulin, however, IL-4 failed to induce tyrosine phosphorylation of Shc or association of Shc with GRB2 [38].
• We recently reported that interleukin-3, Steel factor, and erythropoietin all induce the tyrosine phosphorylation of Shc and its association with Grb2 in hemopoietic cell lines [39].

Other interactions of GRB2

• To relate the effects on gene transcription to a functional ERBB2 protein, signaling from the receptor was inhibited by the antibody 4D5, which blocks phosphorylation of ERBB2 on tyrosine residues and association of the protein with the GRB2/Sem5 protein [40].
• In addition to the EGF receptor, PI3K-C2beta(2-298) also isolated both Shc and Grb2 from A431 cell lysates [41].
• Activation of the epidermal growth factor (EGF) receptor induces formation of EGF receptor- and Grb2-containing clathrin-coated pits [42].
• GAB1 was also associated with the molecular adapter GRB2 in unstimulated cells, and this association dramatically increased after Epo stimulation [43].
• Phospho-Y1230/Y1231 directly recruits growth factor receptor-bonus protein (GRB2) to the receptor, inducing the activation of both AKT and extracellular signal-related kinase 1/2 (ERK1/2) signaling [44].

Analytical, diagnostic and therapeutic context of GRB2

• To position the locus at a much finer resolution, we have isolated the human GRB2 gene in three different cosmids, which we have mapped by fluorescence in situ hybridization to the long arm of human chromosome 17 (17q24-q25) [23].
• Microinjection of Grb3-3 into Swiss 3T3 fibroblasts induced apoptosis [45].
• Employing affinity binding, blot overlay and co-immunoprecipitation assays, we demonstrate an interaction between Grb2 and magicin [46].
• For further analyses, Gab1 mutants were generated by PCR to test in vivo residues thought to be crucial for Grb2 SH3(C) binding [31].
• While failing to induce Shc/Grb2 association, ligation of the TCR/CD3 receptor in Jurkat T-cells induced hSos1-Grb2 complexes [47].

References