Open Access

Stress-induced expression of p53 target genes is insensitive to SNW1/SKIP downregulation

Cellular & Molecular Biology LettersAn International Journal201116:12

https://doi.org/10.2478/s11658-011-0012-1

Received: 19 December 2010

Accepted: 28 March 2011

Published: 3 April 2011

Abstract

Pharmacological inhibition of protein kinases that are responsible for the phosphorylation of the carboxy-terminal domain (CTD) of RNA Pol II during transcription by 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole (DRB) leads to severe inhibition of mRNA synthesis and activates p53. Transcription of the p53 effectors that are induced under these conditions, such as p21 or PUMA, must bypass the requirement for CTD phosphorylation by the positive elongation factor P-TEFb. Here, we have downregulated SNW1/SKIP, a splicing factor and a transcriptional co-regulator, which was found to interact with P-TEFb and synergistically affect Tat-dependent transcription elongation of HIV 1. Using the colon cancer derived cell line HCT116, we have found that both doxorubicin- and DRB-induced expression of p21 or PUMA is insensitive to SNW1 downregulation by siRNA. This suggests that transcription of stress response genes, unlike, e.g., the SNW1-sensitive mitosis-specific genes, can proceed uncoupled from regulators that normally function under physiological conditions.

Key words

P-TEFb SNW1 p21 p53 Transcriptional elongation Genotoxic stress

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