title: Interferon gamma induces neurite outgrowth by up-regulation of p35 neuron-specific cyclin-dependent kinase 5 activator via activation of ERK1/2 pathway.
abstract: Interferon gamma (IFN-gamma) is a cytokine predominantly involved in antiproliferative and antiviral responses, immune surveillance, and tumor suppression. However, it has been shown that IFN-gamma is also involved in central nervous system development. Here we studied the underlying mechanism for IFN-gamma-induced neuronal differentiation using the human neuroblastoma Paju cell line. Our results indicate that IFN-gamma treatment led to neurite outgrowth followed by growth arrest in the G1 phase of the cell cycle. IFN-gamma induced ERK1/2 phosphorylation and subsequently the transcription factor early gene response 1, which in turn up-regulated p35 expression and increased cyclin-dependent kinase 5 (Cdk5) activity. IFN-gamma-induced neurite outgrowth was abolished by the treatment of MEK1/2 kinase inhibitors, such as U0126 and PD98059, which inhibit the ERK1/2 activation and subsequently prevent the up-regulation of p35 expression and Cdk5 activity. In agreement with the role of p35-Cdk5 in neuronal differentiation, small interfering RNA targeting Cdk5 abrogate the IFN-gamma-induced neurite outgrowth. Together, these results demonstrate for the first time that IFN-gamma-triggered neuronal differentiation mediated through the up-regulation of p35-associated Cdk5 depends on the activation of the ERK1/2 pathway. Therefore, the present study suggests that IFN-gamma is not only involved in tumorigenicity but also involved in neurogenesis by regulating cell proliferation and differentiation.
authors.affiliation: Department of Pathology and Laboratory Medicine, Winship Cancer Institute, Center for Neurodegenerative Disease, Emory University, Atlanta, Georgia 30322, USA.
authors.forename: Jin H
authors.initials: JH
authors.lastname: Song
authors.forename: Chen Xu
authors.initials: CX
authors.lastname: Wang
authors.forename: Doyoun K
authors.initials: DK
authors.lastname: Song
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Ashfaq
authors.initials: A
authors.lastname: Shuaib
authors.forename: Chunhai
authors.initials: C
authors.lastname: Hao
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D015153:Blotting, Western; D002453:Cell Cycle; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005434:Flow Cytometry; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction; D053221:TNF-Related Apoptosis-Inducing Ligand; D013997:Time Factors; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D000911:Antibodies, Monoclonal; D051017:Apoptosis Regulatory Proteins; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D034741:RNA, Small Interfering; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; C089495:neuronal Cdk5 activator (p25-p35); D007371:Interferon-gamma; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3