Long noncoding <scp>RNAs</scp> are substrates for cytoplasmic capping enzyme

Mukherjee, Avik; Islam, Safirul; Kieser, Rachel; Kiss, Daniel L.; Mukherjee, Chandrama

doi:10.1002/1873-3468.14603

Cited by 3 publications

(5 citation statements)

References 61 publications

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“…Based on these studies, we wondered if cCE has any role in stress response. To address this, we performed in vitro Xrn1 digestion that could degrade uncapped RNAs and separate capped and uncapped RNA as done earlier[10, 19]. U2OS cells were fixed before or after addition of NaAsO 2 and after 2 h recovery from stress.…”

Section: Resultsmentioning

confidence: 99%

“…The RNA was recovered after phenol chloroform extraction followed by ethanol precipitation. RT-qPCR was performed using gene-specific primer pairs against the 5’ ends of the candidate transcripts as done in earlier studies[10, 18, 19]. Here, a synthetic uncapped GFP mRNA and a synthetic capped Renilla luciferase mRNA were used as a positive and negative spike-in control prior to Xrn1 digestion.…”

Section: Methodsmentioning

confidence: 99%

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mRNA capping enzyme exports to cytoplasm, localizes to stress granules and maintains cap homeostasis of the target mRNAs

Gayen

Mukherjee

Majumder

et al. 2023

Preprint

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mRNA decapping is believed to trigger RNA degradation until the identification of cytoplasmic capping that has changed the epitome of RNA stability. Unlike nuclear capping machinery that includes RNA polymerase II bound mRNA Capping Enzyme (CE), N-7 RNA methyl transferase and RNMT activating protein RAM, cytoplasmic capping complex consist of cytoplasmic pool of CE (cCE) and N-7 RNA methyl transferase-RAM along with a few cytoplasmic proteins of various functions. Cytoplasmic capping has been shown to recap selective uncapped mRNAs and maintains cap homeostasis by a cyclic process of decapping and recapping. Thus, it acts as post-transcriptional nexus for the target transcripts. Our data show nuclear export of mammalian CE is regulated by Exportin1 (XPO1) pathway via a conserved Nuclear Export Signal sequence. In order to examine biological function of cCE, we show cCE forms granules during stress and majority of these granules co-localize with SGs. In order to identify how cCE regulates cap homeostasis during stress and recovery, we measured the cap status of specific cCE targeted mRNA transcripts along with non- targeted transcripts during non-stress, stress and recovery phase using Xrm1 susceptibility assay. Our data show cCE targeted mRNA transcripts lost their caps in stress condition when cCE is sequestered in granules. After removal of stress, when cCE is released, the cap status has been restored for these transcripts pointing towards the role of cCE in altering cap homeostasis and thus promoting cellular recovery from stress.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mRNA capping enzyme exports to cytoplasm, localizes to stress granules and maintains cap homeostasis of the target mRNAs

Gayen

Mukherjee

Majumder

et al. 2023

Preprint

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“…19 Interestingly, this mechanism also involves partially targeting long noncoding RNAs within the cytoplasmic environment. 20…”

Section: Overview Of Eukaryotic Mrna Cappingmentioning

confidence: 99%

“…The recapping mechanism effectively reinstates partially truncated RNA to form new mRNA and also executes the recapping of previously decapped mRNA molecules, thereby maintaining the turnover of capped mRNA entities 19 . Interestingly, this mechanism also involves partially targeting long noncoding RNAs within the cytoplasmic environment 20 …”

Section: Overview Of Eukaryotic Mrna Cappingmentioning

confidence: 99%

Viral RNA capping: Mechanisms and antiviral therapy

Chen,

Jiang,

et al. 2024

Journal of Medical Virology

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RNA capping is an essential trigger for protein translation in eukaryotic cells. Many viruses have evolved various strategies for initiating the translation of viral genes and generating progeny virions in infected cells via synthesizing cap structure or stealing the RNA cap from nascent host messenger ribonucleotide acid (mRNA). In addition to protein translation, a new understanding of the role of the RNA cap in antiviral innate immunity has advanced the field of mRNA synthesis in vitro and therapeutic applications. Recent studies on these viral RNA capping systems have revealed startlingly diverse ways and molecular machinery. A comprehensive understanding of how viruses accomplish the RNA capping in infected cells is pivotal for designing effective broad‐spectrum antiviral therapies. Here we systematically review the contemporary insights into the RNA‐capping mechanisms employed by viruses causing human and animal infectious diseases, while also highlighting its impact on host antiviral innate immune response. The therapeutic applications of targeting RNA capping against viral infections and the development of RNA‐capping inhibitors are also summarized.

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“…mRNA capping is also detected in the cytoplasm [7] where RNGTT, RNMT-RAMAC, and an unknown 5’monophosphatase is bound to the scaffold protein NCK1 [8, 9]. In the cytoplasm, the cap of uncapped mRNAs [10] and long noncoding RNAs [11] are restored by the cytoplasmic capping complex, serving as a regulatory mechanism to fine-tune gene expression [10].…”

Section: Introductionmentioning

confidence: 99%

METTL3 alters capping enzyme expression and its activity on ribosomal proteins

del Valle-Morales,

Romano,

et al. 2023

Preprint

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The 5’ cap, catalyzed by RNA guanylyltransferase and 5’-phosphatase (RNGTT), is a vital mRNA modification for the functionality of mRNAs. mRNA capping occurs in the nucleus for the maturation of the functional mRNA and in the cytoplasm for fine-tuning gene expression. Given the fundamental importance of RNGTT in mRNA maturation and expression there is a need to further investigate the regulation of RNGTT. N6-methyladenosine (m6A) is one of the most abundant RNA modifications involved in the regulation of protein translation, mRNA stability, splicing, and export. We sought to investigate whether m6A could regulate the expression and activity of RNGTT. A motif for the m6A writer methyltransferase 3 (METTL3) in the 3’UTR of RNGTT mRNA was identified. Knockdown of METTL3 resulted in destabilizing RNGTT mRNA, and reduced protein expression. Sequencing of capped mRNAs identified an underrepresentation of ribosomal protein mRNA overlapping with 5’ terminal oligopyrimidine (TOP) mRNAs and genes are dysregulated when cytoplasmic capping is inhibited. Pathway analysis identified disruptions in the mTOR and p70S6K pathways. A reduction in RPS6 mRNA capping, protein expression, and phosphorylation was detected with METTL3 knockdown.

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Long noncoding RNAs are substrates for cytoplasmic capping enzyme

Cited by 3 publications

References 61 publications

mRNA capping enzyme exports to cytoplasm, localizes to stress granules and maintains cap homeostasis of the target mRNAs

mRNA capping enzyme exports to cytoplasm, localizes to stress granules and maintains cap homeostasis of the target mRNAs

Viral RNA capping: Mechanisms and antiviral therapy

METTL3 alters capping enzyme expression and its activity on ribosomal proteins

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