Studies on the effect of vesicular stomatitis virus infection and acetaminophen treatment on NF-$\kappa$B activation in mammalian cells

Date of Completion

January 1997

Keywords

Biology, Cell|Biology, Microbiology

Degree

Ph.D.

Abstract

NF-$\kappa$B is a general transcription factor that can be activated by many stimuli including growth factors, viral infection, and oxidative stress. This activation is in turn responsible for triggering the synthesis of several genes involved in early response events such as interferon induction or cell proliferation.^ Vesicular stomatitis virus (VSV) mutant R1, a good inducer of interferon (IFN), was used to study the activation of NF-$\kappa$B in mouse L929 cells. NF-$\kappa$B DNA binding activity was detected as early as 30 min after virus adsorption in nuclear extracts. Virus entry, delivery of viral components into the cytoplasm, and virus genome transcription were required for NF-$\kappa$B activation. Treatment of cells with 2-aminopurine and the antioxidant, PDTC, nearly completely reduced NF-$\kappa$B activation. In cells infected with wild type (wt) VSV, a non-inducer of IFN, NF-$\kappa$B DNA binding activity in the nucleus was delayed for several hours. This delay was at the level of I-$\kappa$B$\alpha$ degradation. Co-infection of wt VSV and VSV R1 resulted in the reduction of VSV R1 promoted NF-$\kappa$B activation. This inhibitory activity of VSV wt was abolished by one hit of UV irradiation. These results suggest the presence of a NF-$\kappa$B activation inhibitor in wt preparations. IFN induction in VSV infected cells may be influenced, among other factors, by the rate of NF-$\kappa$B activation.^ Acetaminophen (APAP) inhibits cell proliferation in Hepa 1-6 cells in the absence of any of covalent binding to intracellular proteins. To investigate the inhibitory effect of APAP on cell proliferation, I investigated its effect on c-myc expression whose product is required for cell proliferation. APAP inhibited c-myc expression after serum stimulation. This inhibition was at the level of NF-$\kappa$B activation and I-$\kappa$B$\alpha$ degradation. APAP was also able to inhibit $\rm H\sb2O\sb2$ induced activation of NF-$\kappa$B. Other activators of NF-$\kappa$B such as TNF-$\alpha$, phorbol esters, or viral infection were not altered by APAP. APAP interfered with serum signaling by inhibiting Raf-1 kinase activity. The inhibition of serum signal transduction may account for the inhibition of Hepa 1-6 cell growth. ^

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