PHAX and CRM1 Are Required Sequentially to Transport U3 snoRNA to Nucleoli

Boulon, Séverine; Verheggen, Céline; Jády, Beáta E.; Girard, Cyrille; Begon-Pescia, Christina; Paul, Conception; Ospina, Jason K.; Kiss, Tamás; Matera, A. Gregory; Bordonne, Rémy; Bertrand, Édouard

doi:10.1016/j.molcel.2004.11.013

Cited by 153 publications

(220 citation statements)

References 32 publications

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“…Importantly, similar Crm1-containing bodies associated with nucleoli (CNoBs) were present in untransfected cells. In some cells, beside this localization, Crm1 was also enriched in bodies distant from nucleoli, in agreement with a previous report that Crm1 is a component of Cajal bodies (Boulon et al, 2004).…”

Section: Cpeb1 Foci Colocalize With Crm1supporting

confidence: 92%

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Nucleocytoplasmic Traffic of CPEB1 and Accumulation in Crm1 Nucleolar Bodies

Ernoult‐Lange

Wilczynska

Harper

et al. 2009

MBoC

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The translational regulator CPEB1 plays a major role in the control of maternal mRNA in oocytes, as well as of subsynaptic mRNAs in neurons. Although mainly cytoplasmic, we found that CPEB1 protein is continuously shuttling between nucleus and cytoplasm. Its export is controlled by two redundant NES motifs dependent on the nuclear export receptor Crm1. In the nucleus, CPEB1 accumulates in a few foci most often associated with nucleoli. These foci are different from previously identified nuclear bodies. They contain Crm1 and were called Crm1 nucleolar bodies (CNoBs). CNoBs depend on RNA polymerase I activity, indicating a role in ribosome biogenesis. However, although they form in the nucleolus, they never migrate to the nuclear envelope, precluding a role as a mediator for ribosome export. They could rather constitute a platform providing factors for ribosome assembly or export. The behavior of CPEB1 in CNoBs raises the possibility that it is involved in ribosome biogenesis.

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Section: Cpeb1 Foci Colocalize With Crm1supporting

confidence: 92%

“…This default is associated with defective pre-40S export. Interestingly, A0 cleavage requires the snRNA U3, and LMB has been shown to prevent the routing of U3 from Cajal bodies, where it is processed, to the nucleolus (Boulon et al, 2004). In this context, CNoBs could also be a platform for processing factors.…”

Section: Role Of Cnobsmentioning

confidence: 99%

Nucleocytoplasmic Traffic of CPEB1 and Accumulation in Crm1 Nucleolar Bodies

Ernoult‐Lange

Wilczynska

Harper

et al. 2009

MBoC

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“…This modification is recognized by Snuportin-1 in association with Importin-β and other factors to import the snRNAs back into the nucleus (30,31). Interestingly, Exportin-1 also has high affinity for the (TMG)-capped small nucleolar RNA (snoRNA) U3 in the nucleus and transports it from Cajal bodies to the nucleoli (32). Another study showed that TGS1 enhances Rev-dependent HIV-1 RNA expression by (TMG)-capping viral mRNAs in the nucleus, thereby increasing recognition by Exportin-1 for transport to the cytoplasm (33).…”

Section: Significancementioning

confidence: 99%

An Exportin-1–dependent microRNA biogenesis pathway during human cell quiescence

Martínez

Hayes

Barr

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The reversible state of proliferative arrest known as "cellular quiescence" plays an important role in tissue homeostasis and stem cell biology. By analyzing the expression of miRNAs and miRNAprocessing factors during quiescence in primary human fibroblasts, we identified a group of miRNAs that are induced during quiescence despite markedly reduced expression of Exportin-5, a protein required for canonical miRNA biogenesis. The biogenesis of these quiescence-induced miRNAs is independent of Exportin-5 and depends instead on Exportin-1. Moreover, these quiescence-induced primary miRNAs (pri-miRNAs) are modified with a 2,2,7-trimethylguanosine (TMG)-cap, which is known to bind Exportin-1, and knockdown of Exportin-1 or trimethylguanosine synthase 1, responsible for (TMG)-capping, inhibits their biogenesis. Surprisingly, in quiescent cells Exportin-1-dependent pri-miR-34a is present in the cytoplasm together with a small isoform of Drosha, implying the existence of a different miRNA processing pathway in these cells. Our findings suggest that during quiescence the canonical miRNA biogenesis pathway is down-regulated and specific miRNAs are generated by an alternative pathway to regulate genes involved in cellular growth arrest.M ost metazoan cells enter a reversible cell-cycle arrest known as "cellular quiescence" when they are exposed to antimitogenic signals or an environment unfavorable for proliferation (1, 2). In mammalian cells, quiescence (also known as "G 0 arrest") is characterized by reduced DNA replication, altered metabolism, increased autophagy, and increased expression of cyclin-dependent kinase inhibitors such as p27 Kip1 (3,4). In vitro, quiescence can be induced in primary cells by serum starvation, contact inhibition, and loss of adhesion to a substrate (5). Quiescence is involved in important cellular processes, including the balance between differentiation and self-renewal in different types of stem cells, and dysregulation of quiescence could favor carcinogenesis. However, the molecular mechanisms that regulate quiescence are poorly understood (6). miRNAs are small, noncoding RNAs ∼22-nt long that regulate the expression of protein-coding genes by base-pairing with the 3′ UTR of mRNAs, repressing the translation and/or inducing the degradation of the target mRNA (7,8). In canonical miRNA biogenesis in mammalian cells, miRNAs are transcribed by RNA polymerase II to produce 7-methylguanosine (m 7 G)-capped primary miRNAs (pri-miRNAs) containing one or more bulged hairpin structures that are recognized by the nuclear microprocessor, which consists of the RNase III enzyme Drosha and the dsRNA-binding protein DGCR8 (DiGeorge syndrome critical region gene 8) (9-12). Specific cleavage of the pri-miRNA by the nuclear microprocessor generates an ∼70-nt stem-loop structure known as the "precursor miRNA" (pre-miRNA), which is recognized and transported to the cytoplasm by 10,11,13). Subsequently, pre-miRNA is cleaved by the cytoplasmic RNase III enzyme Dicer (14-17), generating a double-stranded mature mi...

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“…31,32 Recent work showed that coilin directly binds snoRNAs 33 and that snoRNAs shuttle via CBs before they reach their nucleolar destination. 33,34 Therefore it is tempting to speculate that snoRNP assembly, like snRNP assembly, takes place in CBs and that coilin plays an important role as well.…”

Section: Coilin Historymentioning

confidence: 99%