Cell growth- and differentiation-dependent regulation of RNA polymerase III transcription

Abstract

1 that share the task of transcribing the information contained in genes into mobile RNA entities. In humans, Pol I transcribes the precursor of the large ribosomal 45S RNA, Pol II transcribes all messenger RNAs, most snRNAs, snoRNAs and micro RNAs and Pol III transcribes a diverse group of small untranslated RNAs that participate in the regulation of transcription, splicing and translation. After transcription, Pol III transcripts are either directly degraded or modified for participation in the regulation and execution of processes in the nucleus and cytoplasm (transcription regulation; RNA processing; ribosome assembly; translation) that ultimately lead to protein synthesis. In the past few years, in part due to the discovery of novel classes of regulatory RNAs such as micro (mi) RNAs and small interfering (si)RNAs, it has become clear that the three classical eukaryotic RNA polymerases have acquired additional layers of complexity during evolution from unicellular to multicellular eukaryotes. For instance, derivatives of Pol II that fulfill specific functions in transcription of siRNAs (Pol IV) or of noncoding RNAs at target loci (Pol V) have been found in Arabidopsis. rNA polymerase iii transcribes small untranslated rNAs that fulfill essential cellular functions in regulating transcription, rNA processing, translation and protein translocation. rNA polymerase iii transcription activity is tightly regulated during the cell cycle and coupled to growth control mechanisms. Furthermore, there are reports of changes in rNA polymerase iii transcription activity during cellular differentiation, including the discovery of a novel isoform of human rNA polymerase iii that has been shown to be specifically expressed in undifferentiated human H1 embryonic stem cells. Here, we review major regulatory mechanisms of rNA polymerase iii transcription during the cell cycle, cell growth and cell differentiation.

Diurnal regulation of RNA polymerase III transcription is under the control of both the feeding–fasting response and the circadian clock

“…Pol III further contributes to translation by synthesizing RNA molecules involved in the maturation of components of the translation machinery, for example Rpph1 RNA (RNase P RNA), required for maturation of pre-tRNA, and Rmrp RNA (MRP RNA), required for maturation of the large ribosomal RNAs (Dumay-Odelot et al 2010). In higher eukaryotes, Pol III transcription is regulated by several activators and repressors, among them MYC, RB1 and other pocket proteins, TRP53, PTEN, and MAF1 (White 2004(White , 2008Bhargava et al 2013).…”

IL-4 Inhibits the Biogenesis of an Epigenetically Suppressive PIWI-Interacting RNA To Upregulate CD1a Molecules on Monocytes/Dendritic Cells

“…3D), indicating that the reduction in td-piR(Glu) could be caused by IL-4-mediated downregulation of tRNA-Glu. It was also shown that tRNA transcription is regulated by various pathways (29). To investigate the pathways that were involved in the regulation of tRNA-Glu by IL-4, the mRNA levels of various genes that participate in the regulation of polymerase III transcription were examined in monocytes.…”

“…Because it is known that IL-4 plays a role in the differentiation of monocytes into DCs, and polymerase III transcription activity is decreased during the differentiation of mammalian cells (29,30), we assessed the level of tRNA-Glu at different time points after IL-4 treatment. IL-4 treatment significantly decreased the levels of td-piR(Glu) and tRNA-Glu (Fig.…”

Contributions of in vitro transcription to the understanding of human RNA polymerase III transcription

“…[63][64][65][66] It was shown that two isoforms of RNAP III are present in human cells that are both capable of transcribing the three distinct types of RNAP III promoters in vitro, but that differed in their cellular expression patterns and functions. 67,68 Specific functions in transcription initiation could be assigned to a ternary subcomplex of RNAP III.…”