The Nuclear DEAD Box RNA Helicase p68 Interacts with the Nucleolar Protein Fibrillarin and Colocalizes Specifically in Nascent Nucleoli during Telophase

Nicol, Samantha M.; Čaušević, Mirsada; Prescott, Alan R.; Fuller-Pace, Frances V.

doi:10.1006/excr.2000.4886

Cited by 56 publications

(49 citation statements)

References 27 publications

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“…p68 protein expression has been shown to be growth and developmentally regulated, suggesting that the protein may play a role in cell proliferation (Lane and Hoeer, 1980;Stevenson et al, 1998). Moreover, p68 exhibits marked changes in its nuclear localization during the cell cycle; in interphase p68 is largely excluded from the nucleoli but it appears to be transiently associated with nascent nucleoli in late telophase, consistent with a possible cell cycle-dependent regulation of function (Iggo et al, 1991;Nicol et al, 2000). In vivo, however, the link between p68 and growth regulation appears to be more complex.…”

Section: Introductionmentioning

confidence: 91%

Overexpression and poly-ubiquitylation of the DEAD-box RNA helicase p68 in colorectal tumours

et al. 2001

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The DEAD box RNA helicase, p68, is upregulated in exponentially growing cells and shows cell cycledependent changes in nuclear localization. Although some other DEAD box proteins have been implicated in cancer, there have been no reports of any link between p68 status and carcinogenesis. In the present study we have analysed specimens from 50 patients with colorectal adenocarcinomas, including cases in which an adenomatous polyp was also present, by immunohistochemistry and Western blotting. Our data indicate that p68 protein is consistently overexpressed in tumours as compared with matched normal tissue. Examination of the levels of p68 mRNA from both normal and tumour tissue showed no obvious speci®c increase in p68 mRNA levels in tumours nor any evidence of underlying mutations in the p68 coding region. Interestingly, however, the accumulated p68 appears to be poly-ubiquitylated, suggesting a possible defect in proteasome-mediated degradation in these tumours. This overexpression/ubiquitylation is observed in both pre-invasive and invasive lesions suggesting that the dysregulation of p68 expression occurs early during tumour development. Finally, we demonstrate that ubiquitylation of p68 occurs in cultured cells, thereby providing a model for the molecular analysis of this process and its potential role in tumorigenesis. Oncogene (2001) 20, 7734 ± 7743.

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Section: Introductionmentioning

confidence: 91%

Overexpression and poly-ubiquitylation of the DEAD-box RNA helicase p68 in colorectal tumours

et al. 2001

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“…Similar patterns of protein localization were observed in other tested lung cancer cell lines (data not shown). To determine the nuclear distribution of PGP9.5 and JAB1, an antibody to ®brillarin, a protein that is only present in the nucleolus in interphase cells (Nicol et al, 2000) was used together with the JAB1 antibody. The result indicated that PGP9.5 and JAB1 colocalized predominantly to the nucleoli in the nucleus (Figure 2, top panel).…”

Section: Colocalization Of Pgp95 and Jab1 In Vivomentioning

confidence: 99%

Interaction and colocalization of PGP9.5 with JAB1 and p27Kip1

et al. 2002

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“…In fact, a direct interaction between FIB and SMN has been demonstrated, although no functional basis for this interaction has been established, including any involvement of FIB in the pathogenesis of spinal muscular atrophy. Another protein, the nuclear DEAD box protein p68, an RNAdependent ATPase and RNA helicase, co-localizes with FIB specifically in nascent nucleoli during telophase (21). As with SMN, no physiological role of its interaction with FIB has been established.…”

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“…The GAR domain is methylated at arginine residues, although the arginine methyltransferase responsible for in vivo methylation has not been identified (23,24). The GAR domain is responsible for the interaction of FIB with both SMN protein and the DEAD box RNA helicase p68 (19,21). A centrally located 90-residue sequence resembles an RNA-binding domain (RBD) present in various snRNPs.…”

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Human Fibrillarin Forms a Sub-complex with Splicing Factor 2-associated p32, Protein Arginine Methyltransferases, and Tubulins α3 and β1 That Is Independent of Its Association with Preribosomal Ribonucleoprotein Complexes

Yanagida

Hayano

Yamauchi

et al. 2004

Journal of Biological Chemistry

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Fibrillarin (FIB, Nop1p in yeast) is an RNA methyltransferase found not only in the fibrillar region of the nucleolus but also in Cajal bodies. FIB is essential for efficient processing of preribosomal RNA during ribosome biogenesis, although its precise function in this process and its role in Cajal bodies remain uncertain. Here, we demonstrate that the human FIB N-terminal glycine-and arginine-rich domain (residues 1-77) and its spacer region 1 (78 -132) interact with splicing factor 2-associated p32 (SF2A-p32) and that the FIB methyltransferase-like domain (133-321) interacts with protein-arginine methyltransferase 5 (PRMT5, Janus kinase-binding protein 1). We also show that these proteins associate with several additional proteins, including PRMT1, tubulin ␣3, and tubulin ␤1 to form a sub-complex that is principally independent of the association of FIB with preribosomal ribonucleoprotein complexes that co-immunoprecipitate with the sub-complex in human cells expressing FLAG-tagged FIB. Based on the physical association of FIB with SF2A-p32 and PRMTs, as well as the other reported results, we propose that FIB may coordinate both RNA and protein methylation during the processes of ribosome biogenesis in the nucleolus and RNA editing such as small nuclear (nucleolar) ribonucleoprotein biogenesis in Cajal bodies.Fibrillarin (FIB) 1 is the most abundant protein in the fibrillar regions of the nucleolus where ribosomal RNA transcription and early preribosomal RNA (pre-rRNA) processing take place (1, 2). FIB is also found in Cajal bodies, subnuclear organelles that contain distinct components involved in RNA transcription and editing such as mRNA splicing and small nuclear (nucleolar) ribonucleoprotein (sn(o)RNP) biogenesis (3, 4). FIB is a component of a ribonucleoprotein (RNP) complex that contains U3, U8, and U13 small nucleolar RNAs that exhibit consensus sequence elements denoted box C (5Ј-UGAUGA-3Ј) and box D (5Ј-CUGA-3Ј) (5). The FIB RNP associates with Nop56p, Nop5p/58p, and a 15.5-kDa protein (a counterpart of yeast Snu13p) to form box C/D snoRNP complexes that function in site-specific 2Ј-O-methylation of pre-rRNA (6 -9). FIB is the methyltransferase that catalyzes this 2Ј-O-methylation (10).FIB, or Nop1p in the yeast Saccharomyces cerevisiae, is highly conserved in eukaryotes with respect to sequence, structure, and function (11-17). Deletion of the Nop1 gene in yeast results in inhibition of 2Ј-O-ribose methylation and pre-rRNA processing at sites A 0 to A 2 , indicating that Nop1p is directly involved in both pre-rRNA methylation and processing and ultimately in ribosome assembly (18). Although human FIB is the functional homolog of yeast Nop1p, it only partially complements a yeast nop1-defective mutant (15). Human FIB is a nucleolar autoantigen for the non-hereditary immune disease scleroderma (14). FIB co-localizes with the survival motor neuron (SMN) gene product in both nucleoli and Cajal bodies/gems of primary neurons (19,20). SMN is linked to one of the most common inheritable causes of childho...

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The Nuclear DEAD Box RNA Helicase p68 Interacts with the Nucleolar Protein Fibrillarin and Colocalizes Specifically in Nascent Nucleoli during Telophase

Cited by 56 publications

References 27 publications

Overexpression and poly-ubiquitylation of the DEAD-box RNA helicase p68 in colorectal tumours

Overexpression and poly-ubiquitylation of the DEAD-box RNA helicase p68 in colorectal tumours

Interaction and colocalization of PGP9.5 with JAB1 and p27Kip1

Human Fibrillarin Forms a Sub-complex with Splicing Factor 2-associated p32, Protein Arginine Methyltransferases, and Tubulins α3 and β1 That Is Independent of Its Association with Preribosomal Ribonucleoprotein Complexes

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