title: Integrin activation and neurotrophin signaling cooperate to enhance neurite outgrowth in sensory neurons.
abstract: Neurite growth is influenced by many factors, including the availability of trophic support as well as the extracellular environment. In this study, we have investigated whether attachment to a permissive culture substrate such as laminin is sufficient to promote neurite outgrowth from dorsal root ganglion neurons in the absence of added nerve growth factor (NGF) and whether this attachment can enhance the response of these neurons to NGF. Adult dorsal root ganglia neurons plated on surfaces coated with a thin film of laminin exhibited increased neurite outgrowth. This effect was integrin-dependent as it was attenuated by treatment with RGD (arginine-glycine-aspartate) peptides and by a beta1-integrin blocking antibody. The addition of NGF resulted in a significant increase in the integrin-dependent outgrowth. We have correlated this increase in growth with increased expression of integrin subunits and activation of known downstream signaling intermediates such as focal adhesion kinase, Src, and Akt. We have also examined pathway cooperation through the use of an Src-specific inhibitor, PP2, and a beta1-integrin blocking antibody, beta1i, by observing downstream signaling intermediates in both integrin and growth factor signaling pathways. These results are among the first to detail the importance of interactions between neurotrophin- and integrin-activated signaling in adult primary neurons.
authors.affiliation: Division of Basic Medical Sciences, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B 3V6, Canada.
authors.forename: Budd A
authors.initials: BA
authors.lastname: Tucker
authors.forename: Masuma
authors.initials: M
authors.lastname: Rahimtula
authors.forename: Karen M
authors.initials: KM
authors.lastname: Mearow
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000906:Antibodies / Q000494:pharmacology; D015153:Blotting, Western; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002452:Cell Count; D002478:Cells, Cultured; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005109:Extracellular Matrix / Q000502:physiology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D005727:Ganglia, Spinal / Q000166:cytology*; D007150:Immunohistochemistry / Q000379:methods; D016023:Integrins / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D007797:Laminin / Q000502:physiology; D008297:Male; D020932:Nerve Growth Factor / Q000494:pharmacology; D016501:Neurites / Q000187:drug effects / Q000502:physiology*; D009475:Neurons, Afferent / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009842:Oligopeptides / Q000378:metabolism / Q000494:pharmacology; D011107:Polylysine / Q000502:physiology; D011134:Polysaccharides / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D011743:Pyrimidines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
chemical_list: C412373:AG 1879; D000906:Antibodies; D004791:Enzyme Inhibitors; D016023:Integrins; D007797:Laminin; D009842:Oligopeptides; D011134:Polysaccharides; D011518:Proto-Oncogene Proteins; D011743:Pyrimidines; C040475:Src peptide; D011107:Polylysine; C010491:neurotropin; C047981:arginyl-glycyl-aspartic acid; D020932:Nerve Growth Factor; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt