Understanding the mechanism of transcription of the genes that code for 45S pre-ribosomal RNA is essential if we are to understand both normal and abnormal growth processes, e.g. wound healing and neoplasia. Ribosome biogenesis, and therefore the expression of the ribosomal RNA genes, is coordinated with the rate of cell growth, and responds to a variety of signals, depending upon the cell type studied. The long-term objective of our research is to determine the mechanism(s) by which ribosomal RNA gene (rDNA) transcription is regulated. At least two trans-acting factors are required for accurate and efficient rDNA transcription, SL-1, and UBF. SL-1 is required for transcription while UBF activates transcription. Recent studies demonstrate that there are several ways in which rDNA transcription is regulated. One is the regulation of the ability of RNA polymerase I to initiate transcription. It has not been clear how many factors control the ability of pol I to initiate transcription. Two of the factors, Rrn3/TIF-IA and TFIC were believed to be the same factor. We demonstrated that they are two different factors. The yeast Rrn3 gene is essential for cell viability, and experiments in mammalian cells demonstrate that mammalian Rrn3 is essential for ribosomal gene transcription. However, there is considerable controversy concerning the role of Rrn3 in transcription, e.g. is it required for the recruitment of pol I to the rDNA promoter? Moreover, our data demonstrate fundamental differences between the mechanisms that regulate Rrn3 function in yeast and mammalian cells. Two of our goals focus on the determination of the role of Rrn3 in rDNA transcription and the mechanism(s) that regulate Rrn3 activity.
Our third aim focuses on the role of PAF53, a second polymerase associated factor. Several lines of evidence suggest that PAF53 is an important component of the apparatus that regulates rDNA transcription. Antibodies to PAF53 block rDNA transcription, and the association of RNA polymerase I with PAF53 correlates with the rate of rDNA transcription. For example, PAF53 levels, but not core RNA polymerase I levels are reduced when NIH 3T3 cells are serum starved, while serum starvation causes the dissociation of PAF53 from RNA polymerase I in 3T6 cells. However, the role of PAF53 in rDNA transcription is yet to be defined. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM069841-04
Application #
7486224
Study Section
Molecular Genetics C Study Section (MGC)
Program Officer
Tompkins, Laurie
Project Start
2005-09-01
Project End
2010-08-31
Budget Start
2008-09-01
Budget End
2010-08-31
Support Year
4
Fiscal Year
2008
Total Cost
$216,697
Indirect Cost
Name
University of Oklahoma Health Sciences Center
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
878648294
City
Oklahoma City
State
OK
Country
United States
Zip Code
73117
Rothblum, Lawrence I; Rothblum, Katrina; Chang, Eugenie (2017) PAF53 is essential in mammalian cells: CRISPR/Cas9 fails to eliminate PAF53 expression. Gene 612:55-60
Penrod, Yvonne; Rothblum, Katrina; Cavanaugh, Alice et al. (2015) Regulation of the association of the PAF53/PAF49 heterodimer with RNA polymerase I. Gene 556:61-7
Rothblum, Katrina; Hu, Qiyue; Penrod, Yvonne et al. (2014) Selective inhibition of rDNA transcription by a small-molecule peptide that targets the interface between RNA polymerase I and Rrn3. Mol Cancer Res 12:1586-96
Stepanchick, Ann; Zhi, Huijun; Cavanaugh, Alice H et al. (2013) DNA binding by the ribosomal DNA transcription factor rrn3 is essential for ribosomal DNA transcription. J Biol Chem 288:9135-44
Hannan, K M; Sanij, E; Rothblum, L I et al. (2013) Dysregulation of RNA polymerase I transcription during disease. Biochim Biophys Acta 1829:342-60
Penrod, Yvonne; Rothblum, Katrina; Rothblum, Lawrence I (2012) Characterization of the interactions of mammalian RNA polymerase I associated proteins PAF53 and PAF49. Biochemistry 51:6519-26
DuRose, Jenny B; Scheuner, Donalyn; Kaufman, Randal J et al. (2009) Phosphorylation of eukaryotic translation initiation factor 2alpha coordinates rRNA transcription and translation inhibition during endoplasmic reticulum stress. Mol Cell Biol 29:4295-307
Cavanaugh, Alice H; Evans, Ann; Rothblum, Lawrence I (2008) Mammalian Rrn3 is required for the formation of a transcription competent preinitiation complex containing RNA polymerase I. Gene Expr 14:131-47
Cheung, Joseph Y; Rothblum, Lawrence I; Moorman, J Randall et al. (2007) Regulation of cardiac Na+/Ca2+ exchanger by phospholemman. Ann N Y Acad Sci 1099:119-34