Alteration of tyrosine hydroxylase activity in PC12 cells infected with herpes simplex virus type 1.
During infection with herpes simplex virus type 1 (HSV-1) the activity of tyrosine hydroxylase (TH) in PC12 pheochromocytoma cells was initially depressed reaching a nadir at 6 hours post-inoculation, but recovered rapidly with a return to baseline activity by 8 to 9 hours post-inoculation. Subsequently, TH activity again fell with a second more variable rise in activity occurring at 24 hours post-inoculation. Studies with metabolic inhibitors and 2 temperature-sensitive viral mutants indicated that these alterations of TH activity were dissociated from morphological cytopathology and likely required expression of "late" viral gene products. Immunotitration using anti-TH antibody suggested that early depression of TH activity resulted principally from loss of enzyme protein rather than simple enzyme inactivation, and that reconstitution of activity at 9 hours was related to augmented enzyme synthesis. These observations illustrate the complexity of perturbed cellular metabolism during HSV-1 infection and suggest involvement of two unexpected processes: alteration of a specialized cell function as a result of viral genes expressed late in the replicative cycle, and augmented synthesis of a cell-coded gene product during the course of infection.
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D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007158:Immunologic Techniques; D010673:Pheochromocytoma; D018139:Simplexvirus / Q000502:physiology* / Q000528:radiation effects; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*; D014466:Ultraviolet Rays
D003609:Dactinomycin; D003513:Cycloheximide; D014446:Tyrosine 3-Monooxygenase