title: p52Shc is required for CXCR4-dependent signaling and chemotaxis in T cells.
abstract: ShcA is an important mediator of Ras/MAPK activation in PTK-regulated pathways triggered by surface receptors. This function is subserved by the constitutively expressed p52-kDa isoform. Besides activating Ras, p52Shc couples the TCR to Rho GTPases, and thereby participates in actin cytoskeleton remodeling in T cells. Here we have addressed the potential involvement of p52Shc in T-cell chemotaxis and the role of the phosphorylatable tyrosine residues, YY239/240 and Y317, in this process. We show that CXCR4 engagement by the homeostatic chemokine, SDF-1alpha, results in p52Shc phosphorylation and its assembly into a complex that includes Lck, ZAP-70, and Vav. This process was found to be both Lck and Gi dependent. Expression of p52Shc mutants lacking YY239/240 or Y317, or p52Shc deficiency, resulted in a profound impairment in CXCR4 signaling and SDF-1alpha-dependent chemotaxis, underscoring a crucial role of p52Shc as an early component of the CXCR4 signaling cascade. p52Shc was also found to be required for ligand-dependent CXCR4 internalization independently of tyrosine phosphorylation. Remarkably, CXCR4 engagement promoted phosphorylation of the zeta chain of the TCR/CD3 complex, which was found to be essential for CXCR4 signaling, as well as for SDF-1alpha-dependent receptor endocytosis and chemotaxis, indicating that CXCR4 signals by transactivating the TCR.
authors.affiliation: Departments of Evolutionary Biology, European Institute of Oncology, Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Patrussi
authors.forename: Cristina
authors.initials: C
authors.lastname: Ulivieri
authors.forename: Orso Maria
authors.initials: OM
authors.lastname: Lucherini
authors.forename: Silvia Rossi
authors.initials: SR
authors.lastname: Paccani
authors.forename: Alessandra
authors.initials: A
authors.lastname: Gamberucci
authors.forename: Luisa
authors.initials: L
authors.lastname: Lanfrancone
authors.forename: Pier Giuseppe
authors.initials: PG
authors.lastname: Pelicci
authors.forename: Cosima T
authors.initials: CT
authors.lastname: Baldari
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology*; D002118:Calcium; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000235:genetics / Q000378:metabolism; D002633:Chemotaxis; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D019169:Jurkat Cells; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000235:genetics / Q000378:metabolism; D051567:Proto-Oncogene Proteins c-vav / Q000235:genetics / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000235:genetics / Q000378:metabolism*; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013601:T-Lymphocytes / Q000502:physiology*; D015533:Transcriptional Activation; D014443:Tyrosine / Q000378:metabolism; D051746:ZAP-70 Protein-Tyrosine Kinase / Q000235:genetics / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D051567:Proto-Oncogene Proteins c-vav; D011948:Receptors, Antigen, T-Cell; D019718:Receptors, CXCR4; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014443:Tyrosine; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051746:ZAP-70 Protein-Tyrosine Kinase; D002118:Calcium