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Phosphorylation of the RNA polymerase II largest subunit during heat shock and inhibition of transcription in hela cells
Author(s) -
Dubois MarieFrançOise,
Bellier Sylvain,
Seo SookJae,
Bensaude Olivier
Publication year - 1994
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041580305
Subject(s) - rna polymerase ii , phosphorylation , microbiology and biotechnology , transcription (linguistics) , dephosphorylation , protein subunit , heat shock , biology , rna polymerase , transcription factor ii d , heat shock protein , gene expression , biochemistry , promoter , rna , phosphatase , gene , linguistics , philosophy
The phosphorylation of the C‐terminal domain (CTD) of the largest subunit of eukaryotic RNA polymerase II has been investigated in HeLa cells exposed to heat shock. In control cells, the phosphorylated subunit, IIo, and the dephosphorylated subunit, IIa, were found in similar amounts. During heat shock, however, the phosphorylated subunit, IIo, accumulated, whereas the amount of IIa subunit decreased. Since phosphorylation of the CTD had been suggested to play a role in the initiation of transcription and since heat shock was known to perturb gene expression at the level of transcription, the phosphorylation state of RNA polymerase II was examined in cells that had been treated with various inhibitors of transcription. Under normal growth temperature, actinomycin D (over 0.1 μ/ml) and okadaic acid, a phosphatase inhibitor, were found to inhibit polymerase dephosphorylation. Whereas 5, 6‐dichlorobenzimidazole riboside (DRB), N‐(2‐[Methylamino]ethyl)‐5‐isoquinolinesulfonamide (H‐8), and actinomycin D (over 5 μ/ml) were found to inhibit polymerase phosphorylation. Actinomycin D concentrations, which inhibited the dephosphorylation process, were lower than those required to inhibit the phosphorylation process. In contrast, during heat shock or exposure to sodium arsenite, a chemical inducer of the heat‐shock response, the phosphorylated subunit, IIo, accumulated even in the presence of inhibitors of transcription such as DRB, H‐8, and actinomycin D. These experiments demonstrated the existence of a heat‐shock‐induced CTD‐phosphorylation process that might contribute to the regulation of transcription during stress. © 1994 Wiley‐Liss, Inc.