Investigation of the RNA polymerase III (pol III) system of eukaryotes including tRNA expression, processing, modification and function, was continued, focusing on transcription termination and the function of the human La antigen which is a prevelant target of autoantibodies in patients suffering from rheumatic disorders such as neonatal lupus, systemic lupus erythematosus and Sjogrens syndrome. Pol III produces small RNAs, including the 5S rRNA and tRNAs essential for protein synthesis, as well as certain virus-encoded transcripts. Pol III is a complex enzyme composed of seventeen subunits with multiple catalytic activities. Human La antigen is a regulatory phosphoprotein that has been shown to serve as a termination factor for pol III, stimulating transcription and directing the posttranscripional maturation of the transcripts, the latter of which includes end-processing, intron removal, base modification, and proper RNA folding. The La phosphoprotein interacts with pol III transcripts by recognizing their 3 terminal UUU-OH motifs (which result from transcription termination), found at the ends of all newly synthesized pol III transcripts. Nonphosphorylated La is localized in the cytoplasm where it interacts with certain cellular and viral mRNAs including HIV RNA, hepatitis C RNA. poliovirus mRNA and others. La interacts with the internal ribosome entry sites (IRES) of viral and cellular mRNAs to modulate their translation. Some viral-encoded factors, including the adenovirus E1A protein, modulate pol III activity. Poliovirus protease-3 protein cleaves the phosphorylation site and nuclear localization signals away from the body of the La antigen, leading to a mainly cytoplasmic localization that facilitates La-mediated translation of poliovirus mRNA. We are interested in the tRNA anticodon modifications that impact the codon-usage specific translation of specific mRNAs involved in growth and development. Understanding the mechanisms by which La and other pol III subunits function in RNA production pathways, and how these pathways are controlled during normal development and cellular proliferation, are major goals of this Section. We extended our focus to La-related proteins (LARPs), including human LARP4 and LARP5, mRNA-associated proteins.

Project Start
Project End
Budget Start
Budget End
Support Year
26
Fiscal Year
2013
Total Cost
$1,753,641
Indirect Cost
City
State
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Zip Code
Arimbasseri, Aneeshkumar G; Iben, James; Wei, Fan-Yan et al. (2016) Evolving specificity of tRNA 3-methyl-cytidine-32 (m3C32) modification: a subset of tRNAsSer requires N6-isopentenylation of A37. RNA 22:1400-10
Rijal, Keshab; Maraia, Richard J (2016) Active Center Control of Termination by RNA Polymerase III and tRNA Gene Transcription Levels In Vivo. PLoS Genet 12:e1006253
Arimbasseri, Aneeshkumar G; Maraia, Richard J (2016) RNA Polymerase III Advances: Structural and tRNA Functional Views. Trends Biochem Sci 41:546-59
Lamichhane, Tek N; Arimbasseri, Aneeshkumar G; Rijal, Keshab et al. (2016) Lack of tRNA-i6A modification causes mitochondrial-like metabolic deficiency in S. pombe by limiting activity of cytosolic tRNATyr, not mito-tRNA. RNA 22:583-96
Mattijssen, Sandy; Maraia, Richard J (2016) LARP4 Is Regulated by Tumor Necrosis Factor Alpha in a Tristetraprolin-Dependent Manner. Mol Cell Biol 36:574-84
Arimbasseri, Aneeshkumar G; Maraia, Richard J (2016) A high density of cis-information terminates RNA Polymerase III on a 2-rail track. RNA Biol 13:166-71
Arimbasseri, Aneeshkumar G; Maraia, Richard J (2015) Biochemical analysis of transcription termination by RNA polymerase III from yeast Saccharomyces cerevisiae. Methods Mol Biol 1276:185-98
Rijal, Keshab; Maraia, Richard J; Arimbasseri, Aneeshkumar G (2015) A methods review on use of nonsense suppression to study 3' end formation and other aspects of tRNA biogenesis. Gene 556:35-50
Arimbasseri, Aneeshkumar G; Blewett, Nathan H; Iben, James R et al. (2015) RNA Polymerase III Output Is Functionally Linked to tRNA Dimethyl-G26 Modification. PLoS Genet 11:e1005671
Lamichhane, Tek N; Blewett, Nathan H; Crawford, Amanda K et al. (2015) Erratum for Lamichhane et al., lack of tRNA modification isopentenyl-A37 alters mRNA decoding and causes metabolic deficiencies in fission yeast. Mol Cell Biol 35:1477

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