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The growing pre-mRNA recruits actin and chromatin-modifying factors to transcriptionally active genes.

ABSTRACT: In the dipteran Chironomus tentans, actin binds to hrp65, a nuclear protein associated with mRNP complexes. Disruption of the actin-hrp65 interaction in vivo by the competing peptide 65-2CTS reduces transcription drastically, which suggests that the actin-hrp65 interaction is required for transcription. We show that the inhibitory effect of the 65-2CTS peptide on transcription is counteracted by trichostatin A, a drug that inhibits histone deacetylation. We also show that actin and hrp65 are associated in vivo with p2D10, an evolutionarily conserved protein with histone acetyltransferase activity that acts on histone H3. p2D10 is recruited to class II genes in a transcription-dependent manner. We show, using the Balbiani ring genes of C. tentans as a model system, that p2D10 is cotranscriptionally associated with the growing pre-mRNA. We also show that experimental disruption of the actin-hrp65 interaction by the 65-2CTS peptide in vivo results in the release of p2D10 from the transcribed genes, reduced histone H3 acetylation, and a lower level of transcription activity. Furthermore, antibodies against p2D10 inhibit run-on elongation. Our results suggest that actin, hrp65, and p2D10 are parts of a positive feedback mechanism that contributes to maintaining the active transcription state of a gene by recruiting HATs at the RNA level.

SUBMITTER: Sjolinder M

PROVIDER: S-EPMC1186187 | biostudies-literature | 2005 Aug

REPOSITORIES: biostudies-literature

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The growing pre-mRNA recruits actin and chromatin-modifying factors to transcriptionally active genes.

Sjölinder Mikael M Björk Petra P Söderberg Emilia E Sabri Nafiseh N Farrants Ann-Kristin Ostlund AK Visa Neus N

Genes & development 20050801 16

In the dipteran Chironomus tentans, actin binds to hrp65, a nuclear protein associated with mRNP complexes. Disruption of the actin-hrp65 interaction in vivo by the competing peptide 65-2CTS reduces transcription drastically, which suggests that the actin-hrp65 interaction is required for transcription. We show that the inhibitory effect of the 65-2CTS peptide on transcription is counteracted by trichostatin A, a drug that inhibits histone deacetylation. We also show that actin and hrp65 are ass ...[more]

PMID: 16103215

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Project description:BackgroundTranscription, metabolism and DNA damage response are tightly regulated to preserve the genomic integrity, and O-GlcNAc transferase (OGT) is positioned to connect the three. Prostate cancer is the most common cancer in men, and androgen-ablation therapy halts disease progression. However, a significant number of prostate cancer patients develop resistance against anti-androgens, and this incurable disease is termed castration-resistant prostate cancer (CRPC). We have shown that combined inhibition of OGT and the transcription elongation kinase CDK9 induce CRPC-selective anti-proliferative effects. Here, we explain the functional basis for these combinatorial effects.MethodsWe used comprehensive mass spectrometry profiling of short-term CDK9 inhibitor effects on O-GlcNAcylated proteins in an isogenic cell line system that models transition from PC to CRPC. In addition, we used both ChIP-seq and RNA-seq profiling, and pulldown experiments in multiple CRPC models. Finally, we validated our findings in prostate cancer patient samples.ResultsInhibition of CDK9 results in an OGT-dependent remodeling of the proteome in prostate cancer cells. More specifically, the activity of the DNA damage repair protein MRE11 is regulated in response to CDK9 inhibition in an OGT-dependent manner. MRE11 is enriched at the O-GlcNAc-marked loci. CDK9 inhibition does not decrease the expression of mRNAs whose genes are bound by both O-GlcNAc and MRE11. Combined inhibition of CDK9 and OGT or MRE11 further decreases RNA polymerase II activity, induces DNA damage signaling, and blocks the survival of prostate cancer cells. These effects are seen in CRPC cells but not in normal prostate cells. Mechanistically, OGT activity is required for MRE11 chromatin-loading in cells treated with CDK9 inhibitor. Finally, we show that MRE11 and O-GlcNAc are enriched at the prostate cancer-specific small nucleotide polymorphic sites, and the loss of MRE11 activity results in a hyper-mutator phenotype in patient tumors.ConclusionsBoth OGT and MRE11 are essential for the repair of CDK9 inhibitor-induced DNA damage. Our study raises the possibility of targeting CDK9 to elicit DNA damage in CRPC setting as an adjuvant to other treatments.

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The growing pre-mRNA recruits actin and chromatin-modifying factors to transcriptionally active genes.

Publications

The growing pre-mRNA recruits actin and chromatin-modifying factors to transcriptionally active genes.

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