acid-phosphatase and Poliomyelitis

In HeLa cells, RNA polymerase III (pol III)-mediated transcription is severely inhibited by poliovirus infection. This inhibition is due primarily to the reduction in transcriptional activity of the pol III transcription factor TFIIIC in poliovirus-infected cells. However, the specific binding of TFIIIC to the VAI gene B-box sequence, as assayed by DNase I footprinting, is not altered by poliovirus infection. We have used gel retardation analysis to analyze TFIIIC-DNA complexes formed in nuclear extracts prepared from mock- and poliovirus-infected cells. In mock-infected cell extracts, two closely migrating TFIIIC-containing complexes, complexes I and II, were detected in the gel retardation assay. The slower migrating complex, complex I, was absent in poliovirus-infected cell extracts, and an increase occurred in the intensity of the faster-migrating complex (complex II). Also, in poliovirus-infected cell extracts, a new, rapidly migrating complex, complex III, was formed. Complex III may have been the result of limited proteolysis of complex I or II. These changes in TFIIIC-containing complexes in poliovirus-infected cell extracts correlated kinetically with the decrease in TFIIIC transcriptional activity. Complexes I, II, and III were chromatographically separated; only complex I was transcriptionally active and specifically restored pol III transcription when added to poliovirus-infected cell extracts. Acid phosphatase treatment partially converted complex I to complex II but did not affect the binding of complex II or III. Dephosphorylation and limited proteolysis of TFIIIC are discussed as possible mechanisms for the inhibition of pol III-mediated transcription by poliovirus.

Topics: Acid Phosphatase; DNA; DNA-Binding Proteins; HeLa Cells; Humans; In Vitro Techniques; Macromolecular Substances; Peptide Hydrolases; Phosphorylation; Poliomyelitis; Time Factors; Transcription Factors; Transcription Factors, TFIII; Transcription, Genetic

Topics: Acid Phosphatase; Alkaline Phosphatase; Animals; Central Nervous System Diseases; Haplorhini; Monkey Diseases; Neuroglia; Neurons; Poliomyelitis; Research; Spinal Cord

Topics: Acid Phosphatase; Coloring Agents; Glucuronidase; Glycoside Hydrolases; Muscles; Musculoskeletal Physiological Phenomena; Phosphoric Monoester Hydrolases; Poliomyelitis