title: Inhibition of N1-Src kinase by a specific SH3 peptide ligand reveals a role for N1-Src in neurite elongation by L1-CAM.
abstract: In the mammalian brain the ubiquitous tyrosine kinase, C-Src, undergoes splicing to insert short sequences in the SH3 domain to yield N1- and N2-Src. We and others have previously shown that the N-Srcs have altered substrate specificity and kinase activity compared to C-Src. However, the exact functions of the N-Srcs are unknown and it is likely that N-Src signalling events have been misattributed to C-Src because they cannot be distinguished by conventional Src inhibitors that target the kinase domain. By screening a peptide phage display library, we discovered a novel ligand (PDN1) that targets the unique SH3 domain of N1-Src and inhibits N1-Src in cells. In cultured neurons, PDN1 fused to a fluorescent protein inhibited neurite outgrowth, an effect that was mimicked by shRNA targeting the N1-Src microexon. PDN1 also inhibited L1-CAM-dependent neurite elongation in cerebellar granule neurons, a pathway previously shown to be disrupted in Src-/-mice. PDN1 therefore represents a novel tool for distinguishing the functions of N1-Src and C-Src in neurons and is a starting point for the development of a small molecule inhibitor of N1-Src.
authors.affiliation: Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Keenan
authors.affiliation: Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Wetherill
authors.affiliation: Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
authors.forename: Christopher I
authors.initials: CI
authors.lastname: Ugbode
authors.affiliation: Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Chawla
authors.affiliation: Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
authors.forename: William J
authors.initials: WJ
authors.lastname: Brackenbury
authors.affiliation: Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
authors.forename: Gareth J O
authors.initials: GJ
authors.lastname: Evans
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D008024:Ligands; D051379:Mice; D039842:Neural Cell Adhesion Molecule L1 / Q000502:physiology*; D016501:Neurites / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction; D018909:src Homology Domains; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D008024:Ligands; D039842:Neural Cell Adhesion Molecule L1; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases