Cytoskeletal Filamin A Differentially Modulates RNA Polymerase III Gene Transcription in Transformed Cell Lines

Specificity protein 1 (Sp1) is an important transcription factor implicated in numerous cellular processes. However, whether Sp1 is involved in the regulation of RNA polymerase III (Pol III)-directed gene transcription in human cells remains unknown. Here, we first show that filamin A (FLNA) represses Sp1 expression as well as expression of TFIIB-related factor 1 (BRF1) and general transcription factor III C subunit 2 (GTF3C2) in HeLa, 293T, and SaOS2 cell lines stably expressing FLNA-silencing shRNAs. Both BRF1 promoter 4 (BRF1P4) and GTF3C2 promoter 2 (GTF3C2P2) contain putative Sp1-binding sites, suggesting that Sp1 affects Pol III gene transcription by regulating BRF1 and GTF3C2 expression. We demonstrate that Sp1 knockdown inhibits Pol III gene transcription, BRF1 and GTF3C2 expression, and the proliferation of 293T and HeLa cells, whereas Sp1 overexpression enhances these activities. We obtained a comparable result in a cell line in which both FLNA and Sp1 were depleted. These results indicate that Sp1 is involved in the regulation of Pol III gene transcription independently of FLNA expression. Reporter gene assays showed that alteration of Sp1 expression affects BRF1P4 and GTF3C2P2 activation, suggesting that Sp1 modulates Pol III–mediated gene transcription by controlling BRF1 and GTF3C2 gene expression. Further analysis revealed that Sp1 interacts with and thereby promotes the occupancies of TATA box–binding protein, TFIIAα, and p300 at both BRF1P4 and GTF3C2P2. These findings indicate that Sp1 controls Pol III–directed transcription and shed light on how Sp1 regulates cancer cell proliferation.

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Transcription factor GATA4 drives RNA polymerase III-directed transcription and transformed cell proliferation through a filamin A/GATA4/SP1 pathway

Journal of Biological Chemistry ◽

10.1016/j.jbc.2022.101581 ◽

2022 ◽

pp. 101581

Author(s):

Cheng Zhang ◽

Houliang Zhao ◽

Xiaoye Song ◽

Juan Wang ◽

Shasha Zhao ◽

...

Keyword(s):

Cell Proliferation ◽

Transcription Factor ◽

Rna Polymerase ◽

Rna Polymerase Iii ◽

Filamin A ◽

Transformed Cell ◽

Polymerase Iii

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Relative Affinities of Nucleotide Substrates for the Yeast tRNA Gene Transcription Complex

Zeitschrift für Naturforschung C ◽

10.1515/znc-1992-3-426 ◽

1992 ◽

Vol 47 (3-4) ◽

pp. 320-322 ◽

Cited By ~ 1

Author(s):

Przemyslaw Szafranski ◽

W. Jerzy Smagowicz

Keyword(s):

Rna Polymerase ◽

Gene Transcription ◽

Trna Gene ◽

Rna Polymerase Iii ◽

Rna Polymerases ◽

Yeast Trna ◽

Polymerase Iii ◽

Michaelis Constants ◽

Auxiliary Protein

Abstract Apparent Michaelis constants for nucleotides in transcription of yeast tRN Agene by hom ologous RNA polymerase III with auxiliary protein factors, were found to be remarkably higher in initiation than in elongation of RNA chain. This supports presumptions regarding topological similarities between catalytic centers of bacterial and eukaryotic RNA polymerases.

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Robust repression of tRNA gene transcription during stress requires protein arginine methylation

Life Science Alliance ◽

10.26508/lsa.201800261 ◽

2019 ◽

Vol 2 (3) ◽

pp. e201800261 ◽

Cited By ~ 1

Author(s):

Richoo B Davis ◽

Neah Likhite ◽

Christopher A Jackson ◽

Tao Liu ◽

Michael C Yu

Keyword(s):

Rna Polymerase ◽

Gene Transcription ◽

Protein Function ◽

Transcriptional Repression ◽

Trna Gene ◽

Rna Polymerase Iii ◽

Arginine Methylation ◽

Major Protein ◽

Polymerase Iii ◽

Protein Arginine Methylation

Protein arginine methylation is an important means by which protein function can be regulated. In the budding yeast, this modification is catalyzed by the major protein arginine methyltransferase Hmt1. Here, we provide evidence that the Hmt1-mediated methylation of Rpc31, a subunit of RNA polymerase III, plays context-dependent roles in tRNA gene transcription: under conditions optimal for growth, it positively regulates tRNA gene transcription, and in the setting of stress, it promotes robust transcriptional repression. In the context of stress, methylation of Rpc31 allows for its optimal interaction with RNA polymerase III global repressor Maf1. Interestingly, mammalian Hmt1 homologue is able to methylate one of Rpc31’s human homologue, RPC32β, but not its paralogue, RPC32α. Our data led us to propose an efficient model whereby protein arginine methylation facilitates metabolic economy and coordinates protein-synthetic capacity.

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Distinct Mechanisms for Repression of RNA Polymerase III Transcription by the Retinoblastoma Tumor Suppressor Protein

Molecular and Cellular Biology ◽

10.1128/mcb.24.13.5989-5999.2004 ◽

2004 ◽

Vol 24 (13) ◽

pp. 5989-5999 ◽

Cited By ~ 30

Author(s):

Heather A. Hirsch ◽

Gauri W. Jawdekar ◽

Kang-Ae Lee ◽

Liping Gu ◽

R. William Henry

Keyword(s):

Rna Polymerase ◽

Gene Transcription ◽

Transcriptional Repression ◽

Rna Polymerase Iii ◽

Control Cell ◽

U6 Snrna ◽

Retinoblastoma Tumor Suppressor ◽

Polymerase Iii ◽

U6 Promoter ◽

Retinoblastoma Tumor

ABSTRACT The retinoblastoma (RB) protein represses global RNA polymerase III transcription of genes that encode nontranslated RNAs, potentially to control cell growth. However, RNA polymerase III-transcribed genes exhibit diverse promoter structures and factor requirements for transcription, and a universal mechanism explaining global repression is uncertain. We show that RB represses different classes of RNA polymerase III-transcribed genes via distinct mechanisms. Repression of human U6 snRNA (class 3) gene transcription occurs through stable promoter occupancy by RB, whereas repression of adenovirus VAI (class 2) gene transcription occurs in the absence of detectable RB-promoter association. Endogenous RB binds to a human U6 snRNA gene in both normal and cancer cells that maintain functional RB but not in HeLa cells whose RB function is disrupted by the papillomavirus E7 protein. Both U6 promoter association and transcriptional repression require the A/B pocket domain and C region of RB. These regions of RB contribute to U6 promoter targeting through numerous interactions with components of the U6 general transcription machinery, including SNAPC and TFIIIB. Importantly, RB also concurrently occupies a U6 promoter with RNA polymerase III during repression. These observations suggest a novel mechanism for RB function wherein RB can repress U6 transcription at critical steps subsequent to RNA polymerase III recruitment.

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