Role of Tyrosine Kinases,Protein Kinase C,and Protein Kinase A in the Regulation of Interferon-α Production Induced by Herpes Simplex Virus Type 1

Abstract

Herpes simplex virus 1 (HSV-1) is able to induce interferon-α production by natural IFN-α-producing cells. In this study, signal transduction in this process was examined. It was found that sequestering of calcium by EGTA abolished IFN-α induction by HSV-infected cells. Stimulation of human PBMC by HSV-1-infected fibroblasts resulted in the production of inositol triphosphate (InsP₃) and tyrosine phosphorylation of cellular proteins. The protein kinase C inhibitor, H7, and the tyrosine kinase inhibitor, herbimycin A, were able to suppress IFN-α gene expression as determined by IFN bioassay and RT-PCR. An IFN-α-specific ELISpot assay revealed that herbimycin A and H7 remarkably decreased the number of IFN-α-producing cells. PMA or calcium ionophore A23187 alone did not increase IFN-α production. However, PMA in conjugation with ionophores increased IFN-α production as early as 2 h. HA1004 and 2′,5′-dideoxyadenosine, which are potent inhibitors of PKA pathway, had no effect on IFN-α production. In contrast, BrcAMP, a specific PKA activator, inhibited the IFN-α secretion and number of IFN-α-producing cells and to a lesser extent reduced the level of IFN-α mRNA. Our results indicate that protein kinase C, tyrosine kinases, and protein kinase A are involved in the regulation of IFN-α production in response to HSV-1.