Tyrosine kinase activation by Newcastle disease virus is required for TNF-alpha gene induction in astrocytes.
Astrocytes, when appropriately stimulated, produce a variety of cytokines including TNF-alpha. Production of TNF-alpha by astrocytes stimulated with Newcastle disease virus (NDV) is achieved by transcriptional activation and mRNA stabilization. A PKC-dependent pathway is responsible for a 10-fold increase in TNF-alpha mRNA stability by reducing poly(A) tail removal. The present study examined signal pathways induced by NDV in primary rat astrocytes that are responsible for TNF-alpha gene transcription as well as the possible source of kinase activity required for mRNA stabilization. Transcription of TNF-alpha gene in astrocytes stimulated by NDV or LPS and IFN-gamma was inhibited completely by the tyrosine kinase inhibitor herbimycin, and partially by a PKC inhibitor H7, as determined by nuclear run-on assay. HA-1004, a cyclic nucleotide-dependent kinase inhibitor, showed no effect. These results indicated that tyrosine kinase signaling pathways seemed to precede the activation of PKC in induction of TNF-alpha gene. Increase in tyrosine kinase activity in NDV-infected astrocytes was demonstrated by a two- to threefold increase in tyrosine phosphorylation of Pl-PLC gamma 1. Because astrocytes contain minimal Pl-PLC beta, and NDV-induced TNF-alpha mRNA was affected by pertussis toxin only modestly, Pl-PLC gamma 1 is likely the enzyme responsible for DAG generation and the PKC-dependent mRNA stabilization in response to NDV.
Fisher
S N
SN
Department of Pathology, University of Maryland School of Medicine, Baltimore 21201.
Kim
Y U
YU
Shin
M L
ML
D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001483:Base Sequence; D016227:Benzoquinones; D002467:Cell Nucleus / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D007371:Interferon-gamma / Q000494:pharmacology; D047029:Lactams, Macrocyclic; D008070:Lipopolysaccharides / Q000494:pharmacology; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D009521:Newcastle Disease / Q000235:genetics*; D009522:Newcastle disease virus / Q000472:pathogenicity*; D037342:Pertussis Toxin; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011809:Quinones / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D016227:Benzoquinones; D017931:DNA Primers; D047029:Lactams, Macrocyclic; D008070:Lipopolysaccharides; D016328:NF-kappa B; D011809:Quinones; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D010566:Virulence Factors, Bordetella; D017828:Rifabutin; C020754:herbimycin; D007371:Interferon-gamma; D037342:Pertussis Toxin; D011505:Protein-Tyrosine Kinases; D010727:Phosphoric Diester Hydrolases; D043265:Phosphatidylinositol Diacylglycerol-Lyase