Dataset Information

BLM helicase facilitates RNA polymerase I-mediated ribosomal RNA transcription.

ABSTRACT: Bloom's syndrome (BS) is an autosomal recessive disorder that is invariably characterized by severe growth retardation and cancer predisposition. The Bloom's syndrome helicase (BLM), mutations of which lead to BS, localizes to promyelocytic leukemia protein bodies and to the nucleolus of the cell, the site of RNA polymerase I-mediated ribosomal RNA (rRNA) transcription. rRNA transcription is fundamental for ribosome biogenesis and therefore protein synthesis, cellular growth and proliferation; its inhibition limits cellular growth and proliferation as well as bodily growth. We report that nucleolar BLM facilitates RNA polymerase I-mediated rRNA transcription. Immunofluorescence studies demonstrate the dependance of BLM nucleolar localization upon ongoing RNA polymerase I-mediated rRNA transcription. In vivo protein co-immunoprecipitation demonstrates that BLM interacts with RPA194, a subunit of RNA polymerase I. (3)H-uridine pulse-chase assays demonstrate that BLM expression is required for efficient rRNA transcription. In vitro helicase assays demonstrate that BLM unwinds GC-rich rDNA-like substrates that form in the nucleolus and normally inhibit progression of the RNA polymerase I transcription complex. These studies suggest that nucleolar BLM modulates rDNA structures in association with RNA polymerase I to facilitate RNA polymerase I-mediated rRNA transcription. Given the intricate relationship between rDNA metabolism and growth, our data may help in understanding the etiology of proportional dwarfism in BS.

SUBMITTER: Grierson PM

PROVIDER: S-EPMC3277314 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

BLM helicase facilitates RNA polymerase I-mediated ribosomal RNA transcription.

Grierson Patrick M PM Lillard Kate K Behbehani Gregory K GK Combs Kelly A KA Bhattacharyya Saumitri S Acharya Samir S Groden Joanna J

Human molecular genetics 20111121 5

Bloom's syndrome (BS) is an autosomal recessive disorder that is invariably characterized by severe growth retardation and cancer predisposition. The Bloom's syndrome helicase (BLM), mutations of which lead to BS, localizes to promyelocytic leukemia protein bodies and to the nucleolus of the cell, the site of RNA polymerase I-mediated ribosomal RNA (rRNA) transcription. rRNA transcription is fundamental for ribosome biogenesis and therefore protein synthesis, cellular growth and proliferation; i ...[more]

PMID: 22106380

Similar Datasets

Project description:Transcription-related proteins are frequently identified as targets of sumoylation, including multiple subunits of the RNA polymerase II (RNAPII) general transcription factors (GTFs). However, it is not known how sumoylation affects GTFs or whether they are sumoylated when they assemble at promoters to facilitate RNAPII recruitment and transcription initiation. To explore how sumoylation can regulate transcription genome-wide, we performed SUMO ChIP-seq in yeast and found, in agreement with others, that most chromatin-associated sumoylated proteins are detected at genes encoding tRNAs and ribosomal proteins (RPGs). However, we also detected 147 robust SUMO peaks at promoters of non-ribosomal protein-coding genes (non-RPGs), indicating that sumoylation also regulates this gene class. Importantly, SUMO peaks at non-RPGs align specifically with binding sites of GTFs, but not other promoter-associated proteins, indicating that it is GTFs specifically that are sumoylated there. Predominantly, non-RPGs with SUMO peaks are among the most highly transcribed, have high levels of TFIIF, and show reduced RNAPII levels when cellular sumoylation is impaired, linking sumoylation with elevated transcription. However, detection of promoter-associated SUMO by ChIP might be limited to sites with high levels of substrate GTFs, and promoter-associated sumoylation at non-RPGs may actually be far more widespread than we detected. Among GTFs, we found that TFIIF is a major target of sumoylation, specifically at lysines 60/61 of its Tfg1 subunit, and elevating Tfg1 sumoylation resulted in decreased interaction of TFIIF with RNAPII. Interestingly, both reducing promoter-associated sumoylation, in a sumoylation-deficient Tfg1-K60/61R mutant strain, and elevating promoter-associated SUMO levels, by constitutively tethering SUMO to Tfg1, resulted in reduced RNAPII occupancy at non-RPGs. This implies that dynamic GTF sumoylation at non-RPG promoters, not simply the presence or absence of SUMO, is important for maintaining elevated transcription. Together, our findings reveal a novel mechanism of regulating the basal transcription machinery through sumoylation of promoter-bound GTFs.

Dataset Information

BLM helicase facilitates RNA polymerase I-mediated ribosomal RNA transcription.

Publications

BLM helicase facilitates RNA polymerase I-mediated ribosomal RNA transcription.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets