Silencing of RNA Helicase II/Guα Inhibits Mammalian Ribosomal RNA Production

Henning, Dale; So, Rolando B.; Jin, Runyan; Lau, Lester F.; Valdez, Benigno C.

doi:10.1074/jbc.m310846200

Cited by 74 publications

(88 citation statements)

References 49 publications

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“…Inhibition of DDX21, whether by siRNAmediated depletion or by antibody microinjection, results in a decrease in both 28 S and 18 S rRNA levels in human and Xenopus models (13,18). We demonstrated previously that endogenous c-Jun and DDX21 coimmunoprecipitate from human cancer cells in culture (6).…”

Section: Resultsmentioning

confidence: 99%

“…S1). Considering the established role of DDX21 in rRNA processing (13,18) and the physical association between c-Jun and DDX21, we investigated whether the rRNA processing defect observed in c-Jun-depleted cells is reflected in the expression or subcellular localization of DDX21. Western blot analysis of DDX21 protein expression in either c-Jun siRNAtransfected cells or c-Jun Ϫ/Ϫ mouse embryo fibroblasts (c-Jun Ϫ/Ϫ ) did not reveal any obvious differences in DDX21 expression as compared with c-Jun-expressing cells (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Transfection of HT-1080 and HeLa cells with siRNA duplex oligonucleotides was performed using Oligofectamine (Invitrogen). The following sense siRNA sequences were used for targeting human c-Jun: DDX21, 5Ј-GAUCCUG-AAACAGAGCAUGTT-3 and 5Ј-AACGCAGCAGUUGCAA-ACATT-3; and si-934, 5Ј-AAGAGCAGCUGGGCGAGGAG-ATT-3 and 5Ј-GUGUGGCAUACAAGAAAGATT-3Ј (13). c-Jun and DDX21 were depleted by pooling the respective siRNA oligos to a final concentration of 200 M. In all experiments, a scrambled duplex (5Ј-GUAACAAUGAGAGCACGG-CTT-3) was used as a control.…”

Section: Methodsmentioning

confidence: 99%

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c-Jun Supports Ribosomal RNA Processing and Nucleolar Localization of RNA Helicase DDX21

Holmström

Mialon

Kallio

et al. 2008

Journal of Biological Chemistry

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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c-Jun Supports Ribosomal RNA Processing and Nucleolar Localization of RNA Helicase DDX21

Holmström

Mialon

Kallio

et al. 2008

Journal of Biological Chemistry

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“…4D). We identified a large variety of ribosomal proteins of both the small and large ribosome subunits as well as of several other factors such as fibrillarin, DDX21, Rrs1, Ebp2, and Nol1 (yeast Nop2) to which roles in rRNA processing and ribosome assembly have been assigned in previous studies (56,(63)(64)(65)(66). This result was supported by the observation that Mybbp1a co-migrated with the small and large ribosome subunit pre-ribosomal particles on a polysome sucrose gradient (Fig.…”

Section: Discussionmentioning

confidence: 99%

Myb-binding Protein 1a (Mybbp1a) Regulates Levels and Processing of Pre-ribosomal RNA

Hochstatter

Hölzel

Michaela

et al. 2012

Journal of Biological Chemistry

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Background: rRNA gene transcription and processing have to be coordinated, as they are intimately linked. Results: Mybbp1a regulates RNA Pol I transcription and pre-rRNA processing. Conclusion: Mybbp1a coordinates both processes. Significance: Mybbp1a was shown to be an important regulator of cellular proliferation, related to RNA Pol II genes. We link its function now as well to regulating RNA Pol I genes and to control ribosome biogenesis.

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“…The RNA helicase DDX21 (also called RHII/Gu␣) is necessary for the processing of 20 S prerRNA into 18 S rRNA as well as for the stability of 28 S rRNA in Xenopus (18). Human DDX21 has also been shown to be critical for the production of 28 and 18 S rRNA (19). Mammalian Pes1 is important for multiple steps of processing, including processing of 36, 32, and 12 S pre-rRNA (20).…”

Section: Identification Of Ns-bindingmentioning

confidence: 99%

Critical Role of Nucleostemin in Pre-rRNA Processing

Romanova

Grand

Zhang

et al. 2009

Journal of Biological Chemistry

100

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Nucleostemin is a nucleolar protein widely expressed in proliferating cells. Nucleostemin is involved in the regulation of cell proliferation, and both depletion and overexpression of nucleostemin induce cell cycle arrest through the p53 signaling pathway. Although the presence of p53-independent functions of nucleostemin has been previously suggested, the identities of these additional functions remained to be investigated. Here, we show that nucleostemin has a novel role as an integrated component of ribosome biogenesis, particularly pre-rRNA processing. Nucleostemin forms a large protein complex (>700 kDa) that co-fractionates with the pre-60 S ribosomal subunit in a sucrose gradient. This complex contains proteins related to prerRNA processing, such as Pes1, DDX21, and EBP2, in addition to several ribosomal proteins. We show that the nucleolar retention of DDX21 and EBP2 is dependent on the presence of nucleostemin in the nucleolus. Furthermore, the knockdown of nucleostemin delays the processing of 32 S pre-rRNA into 28 S rRNA. This is accompanied by a substantial decrease of protein synthesis as well as the levels of rRNAs and some mRNAs. In addition, overexpressed nucleostemin significantly promotes the processing of 32 S pre-rRNA. Collectively, these biochemical and functional studies demonstrate a novel role of nucleostemin in ribosome biogenesis. This is a key aspect of the role of nucleostemin in regulating cell proliferation. Nucleostemin (NS)2 is a nucleolar protein preferentially expressed in actively proliferating cells. The structure of NS is characterized by two GTP-binding domains, which are involved in the regulation of its dynamic shuttling between the nucleolus and nucleoplasm (1). NS was originally identified as a nucleolar protein prominently expressed in rat neural stem cells and down-regulated during differentiation of these cells in vitro (2). The same authors also found that NS is widely expressed in neural precursor cells in early mouse embryos as well as in a variety of cancer cells and stem cells, including embryonic stem cells and a hematopoietic stem cell-enriched fraction. NS is generally down-regulated in the early stage of differentiation before exit from the cell cycle. In addition, knockdown of NS significantly inhibits proliferation of cortical stem cells and cancer cells. These initial observations led to suggestions that NS is involved in multipotency in stem cells as well as in the regulation of cancer and stem cell proliferation (2).Recent work, however, has demonstrated that NS is in fact widely expressed in many types of normal proliferating cells at levels similar to those in malignant cells. For instance, NS is expressed in normal kidney cells and renal carcinoma cells at comparable levels as detected in histological sections (3). The expression of NS is significantly up-regulated when normal T lymphocytes are activated by concanavalin A (3) and when bone marrow stem cells are stimulated by fibroblast growth factor 2 (4). Cells in NS-null mouse embryos fail to enter ...

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Silencing of RNA Helicase II/Guα Inhibits Mammalian Ribosomal RNA Production

Cited by 74 publications

References 49 publications

c-Jun Supports Ribosomal RNA Processing and Nucleolar Localization of RNA Helicase DDX21

c-Jun Supports Ribosomal RNA Processing and Nucleolar Localization of RNA Helicase DDX21

Myb-binding Protein 1a (Mybbp1a) Regulates Levels and Processing of Pre-ribosomal RNA

Critical Role of Nucleostemin in Pre-rRNA Processing

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