title: CSK negatively regulates nerve growth factor induced neural differentiation and augments AKT kinase activity.
abstract: Src family kinases are involved in transducing growth factor signals for cellular differentiation and proliferation in a variety of cell types. The activity of all Src family kinases (SFKs) is controlled by phosphorylation at their C-terminal 527-tyrosine residue by C-terminal SRC kinase, CSK. There is a paucity of information regarding the role of CSK and/or specific Src family kinases in neuronal differentiation. Pretreatment of PC12 cells with the Src family kinase inhibitor, PP1, blocked NGF-induced activation of SFKs and obliterated neurite outgrowth. To confirm a role for CSK and specific isoforms of SFKs in neuronal differentiation, we overexpressed active and catalytically dead CSK in the rat pheochromocytoma cell line, PC12. CSK overexpression caused a profound inhibition of NGF-induced activation of FYN, YES, RAS, and ERK and inhibited neurite outgrowth, NGF-stimulated integrin-directed migration and blocked the NGF-induced conversion of GDP-RAC to its GTP-bound active state. CSK overexpression markedly augmented the activation state of AKT following NGF stimulation. In contrast, kinase-dead CSK augmented the activation of FYN, RAS, and ERK and increased neurite outgrowth. These data suggest a distinct requirement for CSK in the regulation of NGF/TrkA activation of RAS, RAC, ERK, and AKT via the differential control of SFKs in the orchestration of neuronal differentiation.
authors.affiliation: Section of Pediatric Hematology/Oncology, Department of Pediatrics, AFLAC Cancer Center and Blood Disorders Services, Emory University School of Medicine, Atlanta, GA 30022, USA.
authors.forename: Nandini
authors.initials: N
authors.lastname: Dey
authors.forename: Brian W
authors.initials: BW
authors.lastname: Howell
authors.forename: Pradip K
authors.initials: PK
authors.lastname: De
authors.forename: Donald L
authors.initials: DL
authors.lastname: Durden
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D004789:Enzyme Activation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects*; D005822:Genetic Vectors; D008565:Membrane Proteins / Q000235:genetics*; D008954:Models, Biological; D009154:Mutation; D020932:Nerve Growth Factor / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects; D016716:PC12 Cells; D010750:Phosphoproteins / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D012190:Retroviridae / Q000235:genetics
chemical_list: D008565:Membrane Proteins; C408142:Pag1 protein, rat; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D020932:Nerve Growth Factor; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt