FXR1a-associated microRNP: A driver of specialized non-canonical translation in quiescent conditions

Bukhari, Syed I. A.; Vasudevan, Shobha

doi:10.1080/15476286.2016.1265197

Cited by 9 publications

(8 citation statements)

References 146 publications

(137 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Recently, alternatives to eIF4E have been shown to be assembling translation RNPs on select mRNAs. Examples are the DAP5/p97 isoform of eIF4G (21)(22)(23)(24)(25); FXR1a/PARN (26,27); tRNA synthetase (28); and eIF3d (29).…”

mentioning

confidence: 99%

The mRNA encoding the JUND tumor suppressor detains nuclear RNA-binding proteins to assemble polysomes that are unaffected by mTOR

Singh

Fritz

Seufzer

et al. 2020

Journal of Biological Chemistry

View full text Add to dashboard Cite

One long-standing knowledge gap is the role of nuclear proteins in mRNA translation. Nuclear RNA helicase A (DHX9/RHA) is necessary for the translation of the mRNAs of JunD proto-oncogene AP-1 transcription factor subunit (JUND) and HIV-1 genes, and nuclear cap-binding protein 1 (NCBP1)/CBP80 is a component of HIV-1 polysomes. The protein kinase mTOR activates canonical messenger ribonucleoproteins (mRNPs) by posttranslationally downregulating the eIF4E inhibitory protein, 4E-BP1. We posited here that NCBP1 and DHX9/RHA (RHA) support a translation pathway of JUND RNA that is independent of mTOR. We present evidence from reciprocal immunoprecipitation experiments indicating that NCBP1 and RHA both are components of mRNPs in several cell types. Moreover, tandem affinity and RT-qPCR results revealed that JUND mRNA is a component of a previously unknown ribonucleoprotein complex. Results from the tandem IP indicated that another component of the JUND-containing ribonucleoprotein complex is NCBP3, a recently identified ortholog of NCBP2/CBP20. We also found that NCBP1, NCBP3, and RHA, but not NCBP2, are components of JUND-containing polysomes. Mutational analysis uncovered two dsRNA-binding domains of RHA that are necessary to tether JUND-NCBP1/NCBP3 to polysomes. We also found that JUND translation is unaffected by inhibition of mTOR, unless RHA was down-regulated by siRNA. These findings uncover a noncanonical cap-binding complex consisting of NCBP1/NCBP3 and indicate that RHA substitutes for eukaryotic translation initiation factor 4E (eIF4E) and eIF4G in activating mTOR-independent translation of the mRNA encoding the tumor suppressor JUND.

show abstract

mentioning

confidence: 99%

The mRNA encoding the JUND tumor suppressor detains nuclear RNA-binding proteins to assemble polysomes that are unaffected by mTOR

Singh

Fritz

Seufzer

et al. 2020

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…To this end, one of the most important layers of regulation is mRNA translation 2 – 5 . For instance, in response to stress or quiescence, canonical translation is diminished and cellular translation becomes more dependent on noncanonical factors 6 , 7 . In proliferating cells, the various phases of the cell cycle likely impose distinct gene expression requirements on the cell, for instance necessitating nucleotide biosynthesis proteins and histones during S-phase or spindle components during mitosis 8 , 9 .…”

Section: Introductionmentioning

confidence: 99%

Cyclin B/CDK1 and Cyclin A/CDK2 phosphorylate DENR to promote mitotic protein translation and faithful cell division

et al. 2022

View full text Add to dashboard Cite

DENR and MCTS1 have been identified as oncogenes in several different tumor entities. The heterodimeric DENR·MCTS1 protein complex promotes translation of mRNAs containing upstream Open Reading Frames (uORFs). We show here that DENR is phosphorylated on Serine 73 by Cyclin B/CDK1 and Cyclin A/CDK2 at the onset of mitosis, and then dephosphorylated as cells exit mitosis. Phosphorylation of Ser73 promotes mitotic stability of DENR protein and prevents its cleavage at Asp26. This leads to enhanced translation of mRNAs involved in mitosis. Indeed, we find that roughly 40% of all mRNAs with elevated translation in mitosis are DENR targets. In the absence of DENR or of Ser73 phosphorylation, cells display elevated levels of aberrant mitoses and cell death. This provides a mechanism how the cell cycle regulates translation of a subset of mitotically relevant mRNAs during mitosis.

show abstract

“…We identified a noncanonical translation mechanism in G0 leukemic cells, which is mediated by microRNAs [29, 34–36]. MicroRNAs generally degrade mRNAs and repress their translation in proliferating cells, by base-pairing with specific sequences in mRNA 3′untranslated regions (UTRs) and by recruiting repressive factors to such mRNAs [37–42]. However, in G0 cells, microRNAs can activate translation of specific mRNAs by a noncanonical translation mechanism [29].…”

Section: Introductionmentioning

confidence: 99%

“…However, in G0 cells, microRNAs can activate translation of specific mRNAs by a noncanonical translation mechanism [29]. In G0 cells, microRNAs form a complex (microRNA-protein complex or microRNP) with RNA-binding proteins, FXR1a and AGO2, in the nucleus [34, 36, 42–45]. This specialized microRNP is recruited to the 3′ UTRs of specific target mRNAs that are unadenylated or possess a short poly (A) tail [29].…”

Section: Introductionmentioning

confidence: 99%

“…PARN becomes active in G0 cells and its binding to the 5′ cap is increased under these conditions [29, 46, 47]. PARN associates with FXR1a-microRNP that also interacts with p97/DAP5, an eIF4G paralog that brings in the 40S ribosomal subunit and mediates cap-dependent noncanonical translation of specific mRNAs in G0 cells, where canonical translation is reduced [29, 42, 48–51].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of MicroRNA-Mediated Translation Activation of In Vitro Transcribed Reporters in Quiescent Cells

Bukhari

Truesdell

Vasudevan

2017

Cellular Quiescence

Self Cite

View full text Add to dashboard Cite

Quiescence (G0) is defined as an assortment of cell cycle arrested states that exhibit distinct properties. Leukemias harbor a subpopulation of G0 cells that can be enriched by growth factor deprivation or serum starvation. Target site reporters with shortened poly(A) tails show translation activation by microRNAs, via a noncanonical mechanism, when introduced into the nucleus of G0 cells. This is because recruitment by the activation causing FXR1a-microRNA-protein complex (FXR1a-microRNP) is nuclear and requires shortened poly(A) tails to avoid repressive factors and canonical translation. When introduced into the cytoplasm, target mRNAs and microRNAs are directed toward repression rather than translation activation. Leukemic cell lines are difficult to transfect but can be routinely nucleofected-where in vitro transcribed mRNA reporters and microRNAs are introduced into the nucleus of G0 leukemic cells. Nucleofection of a microRNA target reporter and either cognate, targeting microRNA, or control microRNA, into the nucleus of G0 cells, enables analysis of translation activation by microRNAs in G0. We discuss a modified protocol that we developed for transfection of mRNAs along with microRNAs to test translation regulation by microRNAs in G0 leukemic cells.

show abstract

FXR1a-associated microRNP: A driver of specialized non-canonical translation in quiescent conditions

Cited by 9 publications

References 146 publications

The mRNA encoding the JUND tumor suppressor detains nuclear RNA-binding proteins to assemble polysomes that are unaffected by mTOR

The mRNA encoding the JUND tumor suppressor detains nuclear RNA-binding proteins to assemble polysomes that are unaffected by mTOR

Cyclin B/CDK1 and Cyclin A/CDK2 phosphorylate DENR to promote mitotic protein translation and faithful cell division

Analysis of MicroRNA-Mediated Translation Activation of In Vitro Transcribed Reporters in Quiescent Cells

Contact Info

Product

Resources

About