Formation of tRNA granules in the nucleus of heat-induced human cells

Miyagawa, Ryu; Mizuno, Risuke; Watanabe, Kazunori; Ijiri, Kenichi

doi:10.1016/j.bbrc.2011.12.150

Cited by 27 publications

(31 citation statements)

References 31 publications

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“…FISH analyses were performed according to our recent report, using a DIG-labelled RNA probe (Roche) (18). Localization of Xrn1 and Xrn2 were determined by immunofluorescence analyses.…”

Section: Methodsmentioning

confidence: 99%

Degradation of initiator tRNA Met by Xrn1/2 via its accumulation in the nucleus of heat-treated HeLa cells

Watanabe

Miyagawa

Tomikawa

et al. 2013

Nucleic Acids Research

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Stress response mechanisms that modulate the dynamics of tRNA degradation and accumulation from the cytoplasm to the nucleus have been studied in yeast, the rat hepatoma and human cells. In the current study, we investigated tRNA degradation and accumulation in HeLa cells under various forms of stress. We found that initiator tRNAMet (tRNA(iMet)) was specifically degraded under heat stress. Two exonucleases, Xrn1 and Xrn2, are involved in the degradation of tRNA(iMet) in the cytoplasm and the nucleus, respectively. In addition to degradation, we observed accumulation of tRNA(iMet) in the nucleus. We also found that the mammalian target of rapamycin (mTOR), which regulates tRNA trafficking in yeast, is partially phosphorylated at Ser2448 in the presence of rapamycin and/or during heat stress. Our results suggest phosphorylation of mTOR may correlate with accumulation of tRNA(iMet) in heat-treated HeLa cells.

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“…FISH analyses were performed according to our recent report, using a DIG-labelled RNA probe (Roche) (18). Localization of Xrn1 and Xrn2 were determined by immunofluorescence analyses.…”

Section: Methodsmentioning

confidence: 99%

Degradation of initiator tRNA Met by Xrn1/2 via its accumulation in the nucleus of heat-treated HeLa cells

Watanabe

Miyagawa

Tomikawa

et al. 2013

Nucleic Acids Research

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“…HIV likely usurped this process as it provides one means by which HIV retrotranscribed complexes gain access to the nuclear interior in neuronal cells (Zaitseva et al 2006). tRNA retrograde nuclear accumulation has also been demonstrated in vertebrate rat hepatoma cells after amino acid deprivation , in Chinese hamster ovary cells upon inhibition of protein synthesis by puromycin (Barhoom et al 2011), and in heat-stressed human cells (Miyagawa et al 2012). However, another group claims that this process is restricted to S. cerevisiae (Pierce and Mangroo 2011 and references therein).…”

Section: Trna Retrograde Nuclear Importmentioning

confidence: 99%

Transfer RNA Post-Transcriptional Processing, Turnover, and Subcellular Dynamics in the YeastSaccharomyces cerevisiae

2013

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Transfer RNAs (tRNAs) are essential for protein synthesis. In eukaryotes, tRNA biosynthesis employs a specialized RNA polymerase that generates initial transcripts that must be subsequently altered via a multitude of post-transcriptional steps before the tRNAs beome mature molecules that function in protein synthesis. Genetic, genomic, biochemical, and cell biological approaches possible in the powerful Saccharomyces cerevisiae system have led to exciting advances in our understandings of tRNA post-transcriptional processing as well as to novel insights into tRNA turnover and tRNA subcellular dynamics. tRNA processing steps include removal of transcribed leader and trailer sequences, addition of CCA to the 39 mature sequence and, for tRNA His , addition of a 59 G. About 20% of yeast tRNAs are encoded by intron-containing genes. The three-step splicing process to remove the introns surprisingly occurs in the cytoplasm in yeast and each of the splicing enzymes appears to moonlight in functions in addition to tRNA splicing. There are 25 different nucleoside modifications that are added post-transcriptionally, creating tRNAs in which 15% of the residues are nucleosides other than A, G, U, or C. These modified nucleosides serve numerous important functions including tRNA discrimination, translation fidelity, and tRNA quality control. Mature tRNAs are very stable, but nevertheless yeast cells possess multiple pathways to degrade inappropriately processed or folded tRNAs. Mature tRNAs are also dynamic in cells, moving from the cytoplasm to the nucleus and back again to the cytoplasm; the mechanism and function of this retrograde process is poorly understood. Here, the state of knowledge for tRNA post-transcriptional processing, turnover, and subcellular dynamics is addressed, highlighting the questions that remain. TABLE OF CONTENTS Abstract 43Introduction 44

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“…However, tRNAs move bidirectionally between the nucleus and the cytoplasm (Shaheen and Hopper 2005;Takano et al 2005;Zaitseva et al 2006;Shaheen et al 2007;Barhoom et al 2011;Miyagawa et al 2012). Newly transcribed, end-processed tRNAs are exported from the nucleus to the cytoplasm via primary tRNA nuclear export.…”

mentioning

confidence: 99%

“…Newly transcribed, end-processed tRNAs are exported from the nucleus to the cytoplasm via primary tRNA nuclear export. Cytoplasmic tRNAs are constitutively imported into the nucleus via retrograde tRNA nuclear import (Shaheen and Hopper 2005;Takano et al 2005;Zaitseva et al 2006;Shaheen et al 2007;Murthi et al 2010;Barhoom et al 2011;Miyagawa et al 2012). The yeast β-importin, Mtr10, is implicated in retrograde tRNA nuclear import (Shaheen and Hopper 2005;Murthi et al 2010).…”

mentioning

confidence: 99%

In vivo biochemical analyses reveal distinct roles of β-importins and eEF1A in tRNA subcellular traffic

Huang

Hopper

2015

Genes Dev.

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Bidirectional tRNA movement between the nucleus and the cytoplasm serves multiple biological functions. To gain a biochemical understanding of the mechanisms for tRNA subcellular dynamics, we developed in vivo β-importin complex coimmunoprecipitation (co-IP) assays using budding yeast. Our studies provide the first in vivo biochemical evidence that two β-importin family members, Los1 (exportin-t) and Msn5 (exportin-5), serve overlapping but distinct roles in tRNA nuclear export. Los1 assembles complexes with RanGTP and tRNA. Both intron-containing pre-tRNAs and spliced tRNAs, regardless of whether they are aminoacylated, assemble into Los1-RanGTP complexes, documenting that Los1 participates in both primary nuclear export and re-export of tRNAs to the cytoplasm. In contrast, β-importin Msn5 preferentially assembles with RanGTP and spliced, aminoacylated tRNAs, documenting its role in tRNA nuclear re-export. Tef1/2 (the yeast form of translation elongation factor 1α [eEF1A]) aids the specificity of Msn5 for aminoacylated tRNAs to form a quaternary complex consisting of Msn5, RanGTP, aminoacylated tRNA, and Tef1/2. Assembly and/or stability of this quaternary complex requires Tef1/2, thereby facilitating efficient re-export of aminoacylated tRNAs to the cytoplasm.

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Formation of tRNA granules in the nucleus of heat-induced human cells

Cited by 27 publications

References 31 publications

Degradation of initiator tRNA Met by Xrn1/2 via its accumulation in the nucleus of heat-treated HeLa cells

Degradation of initiator tRNA Met by Xrn1/2 via its accumulation in the nucleus of heat-treated HeLa cells

Transfer RNA Post-Transcriptional Processing, Turnover, and Subcellular Dynamics in the YeastSaccharomyces cerevisiae

In vivo biochemical analyses reveal distinct roles of β-importins and eEF1A in tRNA subcellular traffic

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