<i>In vitro</i>evidence that eukaryotic ribosomal RNA transcription is regulated by modification of RNA polymerase I

Paule, Marvin R.; Iida, Calvin T.; Perna, Peter J.; Harris, Guy H.; Knoll, Deborah A.; D'Alessio, James M.

doi:10.1093/nar/12.21.8161

Cited by 64 publications

(40 citation statements)

References 32 publications

(20 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When this occurs, rRNA transcription, which in the proliferating cell is 75% of pulse-labeled RNA, ceases completely ( Fig. 1) (23,27). We show here that 5S RNA transcription is coordinately modulated with rRNA.…”

mentioning

confidence: 56%

“…When cells are transferred to starvation medium, they leave the growth/division cycle and begin differentiation into dormant cysts. In the early stages of this process, rRNA transcription is shut off (4,23,27) (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

“…Transcription of rRNA is regulated by modification of the enzyme responsible for its synthesis, RNA polymerase I. Polymerase I purified from transcriptionally active cells is active both in nonspecific assays (transcription of damaged templates) and in specific, promoter-dependent assays in vitro. However, polymerase purified to apparent homogeneity from cysts cannot initiate from promoters even though it retains full activity in the nonspecific assay (4,23). Structurally, a change in the electrophoretic mobility of the 39-kDa subunit correlates with regulation.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Coordinate Regulation of Ribosomal Component Synthesis in Acanthamoeba castellanii: 5S RNA Transcription Is Down Regulated during Encystment by Alteration of TFIIIA Activity

Matthews

Zwick

Paule

1995

Molecular and Cellular Biology

View full text Add to dashboard Cite

Transcription of large rRNA precursor and 5S RNA were examined during encystment of Acanthamoeba castellanii. Both transcription units are down regulated almost coordinately during this process, though 5S RNA transcription is not as completely shut down as rRNA transcription. The protein components necessary for transcription of 5S RNA and tRNA were determined, and fractions containing transcription factors comparable to TFIIIA, TFIIIB, and TFIIIC, as well as RNA polymerase III and a 3-end processing activity, were identified. Regulation of 5S RNA transcription could be recapitulated in vitro, and the activities of the required components were compared. In contrast to regulation of precursor rRNA, there is no apparent change during encystment in the activity of the polymerase dedicated to 5S RNA expression. Similarly, the transcriptional and promoter-binding activities of TFIIIC are not altered in parallel with 5S RNA regulation. TFIIIB transcriptional activity is unaltered in encysting cells. In contrast, both the transcriptional and DNA-binding activities of TFIIIA are strongly reduced in nuclear extracts from transcriptionally inactive cells. These results were analyzed in terms of mechanisms for coordinate regulation of rRNA and 5S RNA expression.The number of ribosomes in the cell is regulated to correspond to the quantitative requirement for protein synthesis. Therefore, the rate of biosynthesis of ribosomes varies with the cellular proliferation rate, in response to cellular growth without cell division (e.g., cardiac hypertrophy [1]), and with significant changes in protein synthesis rates in secretory tissues (e.g., the Drosophila paragonial gland [29] [reviewed in reference 22]). The synthesis of the 80 to 90 components of the ribosome must be coordinately up or down regulated to correspond to changes in ribosome elaboration rate. The mechanisms leading to balanced synthesis of these components is poorly understood. For the ribosomal proteins, regulation occurs at several steps in the biosynthetic pathway, including transcription by RNA polymerase II, processing, translation efficiency, and mRNA stability. The critical regulated step depends on the particular ribosomal protein and the species (2,3,(19)(20)(21)30). rRNA and 5S RNA are transcribed by RNA polymerases I and III, respectively. Thus, various ribosomal components are transcribed by each of the three eukaryotic RNA polymerases. Expression of the stable RNAs is regulated at the transcriptional level. Therefore, the problem of coordinating their expression is, at least in part, one of coordinating transcription of their genes by distinct transcriptional systems. This study investigates the mechanisms involved in coordinating precursor rRNA and 5S RNA transcription in Acanthamoeba castellanii.When starved for essential nutrients, A. castellanii leaves the growth/division cycle and undergoes cellular differentiation into a dormant cyst. When this occurs, rRNA transcription, which in the proliferating cell is 75% of pulse-labeled RNA, ceases comple...

show abstract

mentioning

confidence: 56%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Coordinate Regulation of Ribosomal Component Synthesis in Acanthamoeba castellanii: 5S RNA Transcription Is Down Regulated during Encystment by Alteration of TFIIIA Activity

Matthews

Zwick

Paule

1995

Molecular and Cellular Biology

View full text Add to dashboard Cite

show abstract

“…This activity loss could be reproduced with purified components, and it was shown that it was the polymerase fraction that lost activity when A. castellanii entered stationary phase. Pol Is purified from growing cells or cysts differed in their abilities to specifically initiate rDNA transcription (2,32). In addition, both enzymes had different heat stabilities, a finding which suggested that Pol I itself was modified (32).…”

Section: Discussionmentioning

confidence: 99%

Function of the growth-regulated transcription initiation factor TIF-IA in initiation complex formation at the murine ribosomal gene promoter.

Schnapp¹,

Schnapp²,

Erny³

et al. 1993

Mol. Cell. Biol.

View full text Add to dashboard Cite

Alterations in the rate of cell proliferation are accompanied by changes in the transcription of rRNA genes. In mammals, this growth-dependent regulation of transcription of genes coding for rRNA (rDNA) is due to reduction of the amount or activity of an essential transcription factor, called TIF-IA. Extracts prepared from quiescent cells lack this factor activity and, therefore, are transcriptionally inactive. We have purified TIF-IA from exponentially growing cells and have shown that it is a polypeptide with a molecular mass of 75 kDa which exists as a monomer in solution. Using a reconstituted transcription system consisting of purified transcription factors, we demonstrate that TTF-IA is a bona fide transcription initiation factor which interacts with RNA polymerase I. Preinitiation complexes can be assembled in the absence of TIF-IA, but formation of the first phosphodiester bonds of nascent rRNA is precluded. After initiation, TIF-IA is liberated from the initiation complex and facilitates transcription from templates bearing preinitiation complexes which lack TIF-IA.Despite the pronounced species specificity of class I gene transcription, this growth-dependent factor has been identified not only in mouse but also in human cells. Murine TIF-IA complements extracts from both growth-inhibited mouse and human cells. The analogous human activity appears to be similar or identical to that of TIF-IA. Therefore, despite the fact that the RNA polymerase transcription system has evolved sufficiently rapidly that an rDNA promoter from one species will not function in another species, the basic mechanisms that adapt ribosome synthesis to cell proliferation have been conserved.

show abstract

“…Finally, in apparent analogy to the loss of factor C activity in growth-arrested mammalian cells, encysting cells of the soil amoeba Acanthamoeba castellandi also demonstrate downregulation of rRNA gene transcription as a result of loss of specific initiation competence by the RNA polymerase I (1,48). No specific initiation factor has been separated from the A. castellandi RNA polymerase I catalytic activity, but the A. castellanii RNA polymerase I (which has twice as many copurifying polypeptides as does the mammalian enzyme) could bind its C* equivalent more tightly.…”

Section: -Nt)mentioning

confidence: 99%

Factor C*, the specific initiation component of the mouse RNA polymerase I holoenzyme, is inactivated early in the transcription process.

Brun¹,

Ryan²,

Sollner‐Webb³

1994

Mol. Cell. Biol.

View full text Add to dashboard Cite

Factor C* is the component of the RNA polymerase I holoenzyme (factor C) that allows specific transcriptional initiation on a factor D (SL1)- and UBF-activated rRNA gene promoter. The in vitro transcriptional capacity of a preincubated rDNA promoter complex becomes exhausted very rapidly upon initiation of transcription. This is due to the rapid depletion of C* activity. In contrast, C* activity is not unstable in the absence of transcription, even in the presence of nucleoside triphosphates (NTPs). By using 3'dNTPs to specifically halt elongation, C* is seen to remain active through transcription complex assembly, initiation, and the first approximately 37 nucleotides of elongation, but it is inactivated before synthesis proceeds beyond approximately 40 nucleotides. When elongation is halted before this critical distance, the C* remains active and on that template complex, greatly extending the kinetics of transcription and generating manyfold more transcripts than would have been synthesized if elongation had proceeded past the critical distance where C* is inactivated. In complementary in vivo analysis under conditions where C* activity is not replenished, C* activity becomes depleted from cells, but this also occurs only when there is ongoing rDNA transcription. Thus, both in vitro and in vivo, the specific initiation-conferring component of the RNA polymerase I holoenzyme is used stoichiometrically in the transcription process.

show abstract

In vitroevidence that eukaryotic ribosomal RNA transcription is regulated by modification of RNA polymerase I

Cited by 64 publications

References 32 publications

Coordinate Regulation of Ribosomal Component Synthesis in Acanthamoeba castellanii: 5S RNA Transcription Is Down Regulated during Encystment by Alteration of TFIIIA Activity

Coordinate Regulation of Ribosomal Component Synthesis in Acanthamoeba castellanii: 5S RNA Transcription Is Down Regulated during Encystment by Alteration of TFIIIA Activity

Function of the growth-regulated transcription initiation factor TIF-IA in initiation complex formation at the murine ribosomal gene promoter.

Factor C*, the specific initiation component of the mouse RNA polymerase I holoenzyme, is inactivated early in the transcription process.

Contact Info

Product

Resources

About