An intact Box C sequence in the U3 snRNA is required for binding of fibrillarin, the protein common to the major family of nucleolar snRNPs. EMBO J

Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale School of Medicine, New Haven, CT 06511.
The EMBO Journal (Impact Factor: 10.43). 10/1991; 10(9):2645-51.
Source: PubMed


The mammalian U3 snRNP is one member of a recently described family of nucleolar snRNPs which also includes U8, U13, U14, X and Y. All of these snRNPs are immunoprecipitable by anti-fibrillarin autoantibodies, suggesting the existence of a common binding site for the 34 kDa fibrillarin (Fb) protein. Two short nucleotide sequences, called Boxes C and D, present in each of these RNAs are the most likely sites for fibrillarin binding. We have developed a HeLa in vitro assembly system for binding of fibrillarin to human U3 snRNA. Reconstitution of the input RNA is specific in our assay since four of the other nucleolar small RNAs (U8, U13, X and Y) which have Boxes C and D become immunoprecipitable by anti-fibrillarin whereas two RNAs which lack these sequences (5S and 5.8S) do not. Deletion analyses of the U3 snRNA demonstrate that the presence of Box C but not Box D is required for fibrillarin binding. Moreover, seven single or double site-specific mutations in the U3 Box C abolish binding. The role of the Box C-fibrillarin interaction in the biogenesis of the Fb snRNPs is discussed.

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    • "If true for sporadic cases, Snord3A levels may be used to identify at risk individuals of all etiologies, and in the future, as a marker of treatment success. Snord3A, or in its other denomination U3 small nucleolar RNA, was shown to be part of the complex comprising fibrillarin and the survival motor neuron gene (SMN1) [41], [42], implicated in ALS pathogenesis via oxidative pathways [36]. On another note, other SnoRnas were recently recognized as mediators of oxidative and ER stress [25]. "
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    ABSTRACT: Since preventive treatments for prion disease require early identification of subjects at risk, we searched for surrogate peripheral markers characterizing the asymptomatic phases of such conditions. To this effect, we subjected blood mRNA from E200K PrP CJD patients and corresponding family members to global arrays and found that the expression of Snord3A, a non-coding RNA transcript, was elevated several times in CJD patients as compared to controls, while asymptomatic carriers presented intermediate Snord3A levels. In the brains of TgMHu2ME199K mice, a mouse model mimicking for E200K CJD, Snord 3A levels were elevated in an age and disease severity dependent manner, as was the case for brains of these mice in which disease was exacerbated by copper administration. Snord3A expression was also elevated in scrapie infected mice, but not in PrP(0/0) mice, indicating that while the expression levels of this transcript may reflect diverse prion etiologies, they are not related to the loss of PrP(C)'s function. Elevation of Snord3A was consistent with the activation of ATF6, representing one of the arms of the unfolded protein response system. Indeed, SnoRNAs were associated with reduced resistance to oxidative stress, and with ER stress in general, factors playing a significant role in this and other neurodegenerative conditions. We hypothesize that in addition to its function as a disease marker, Snord3A may play an important role in the mechanism of prion disease manifestation and progression.
    Full-text · Article · Jan 2013 · PLoS ONE
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    • "In 1985, anti-U3-RNP antibodies were isolated by IP techniques [94]. More recently it was shown that the mammalian U3 small nuclear RNP (snRNP) is one member of a family of nucleolar snRNPs that are immunoprecipitable by anti-fibrillarin autoantibodies [95]. AFA are present in about 4% of patients with SSc and are mutually exclusive with ACA, anti-Scl-70, and anti-RNAP [96]. "
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    ABSTRACT: Scleroderma (systemic sclerosis) is associated with several autoantibodies, each of which is useful in the diagnosis of affected patients and in determining their prognosis. Anti-centromere antibodies (ACA) and anti-Scl-70 antibodies are very useful in distinguishing patients with systemic sclerosis (SSc) from healthy controls, from patients with other connective tissue disease, and from unaffected family members. Whereas ACA often predict a limited skin involvement and the absence of pulmonary involvement, the presence of anti-Scl-70 antibodies increases the risk for diffuse skin involvement and scleroderma lung disease. Anti-fibrillarin autoantibodies (which share significant serologic overlap with anti-U3-ribonucleoprotein antibodies) and anti-RNA-polymerase autoantibodies occur less frequently and are also predictive of diffuse skin involvement and systemic disease. Anti-Th/To and PM-Scl, in contrast, are associated with limited skin disease, but anti-Th/To might be a marker for the development of pulmonary hypertension. Other autoantibodies against extractable nuclear antigens have less specificity for SSc, including anti-Ro, which is a risk factor for sicca symptoms in patients with SSc, and anti-U1-ribonucleoprotein, which in high titer is seen in patients with SSc/systemic lupus erythematosus/polymyositis overlap syndromes. Limited reports of other autoantibodies (anti-Ku, antiphospholipid) have not established them as being clinically useful in following patients with SSc.
    Preview · Article · Feb 2003 · Arthritis research & therapy
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    • "Fibrillarin is highly conserved in sequence, structure, and function in eukaryotes (Schimmang et al. 1989; Henriquez et al. 1990; Lapeyre et al. 1990; Aris and Blobel 1991; Jansen et al. 1991; Girard et al. 1993; Turley et al. 1993; Cappai et al. 1994; David et al. 1997). Fibrillarin, named Nop1p in yeast, is an essential component of box C/D snoRNPs (Tyc and Steitz 1989; Aris and Blobel 1991; Baserga et al. 1991) that function in site-specific 2′-O-methylation of pre-rRNA (Kiss-Laszlo et al. 1996; Tycowski et al. 1996; Dunbar and Baserga 1998). Fibrillarin is directly involved in many posttranscriptional processes including pre-rRNA processing, pre-rRNA methylation, and ribosome assembly (Tollervey et al. 1993). "
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    ABSTRACT: Cajal bodies (CBs) are subnuclear organelles that contain components of a number of distinct pathways in RNA transcription and RNA processing. CBs have been linked to other subnuclear organelles such as nucleoli, but the reason for the presence of nucleolar proteins such as fibrillarin in CBs remains uncertain. Here, we use full-length fibrillarin and truncated fibrillarin mutants fused to green fluorescent protein (GFP) to demonstrate that specific structural domains of fibrillarin are required for correct intranuclear localization of fibrillarin to nucleoli and CBs. The second spacer domain and carboxy terminal alpha-helix domain in particular appear to target fibrillarin, respectively, to the nucleolar transcription centers and CBs. The presence of the RNP domain seems to be a prerequisite for correct targeting of fibrillarin. Time-lapse confocal microscopy of human cells that stably express fibrillarin-GFP shows that CBs fuse and split, albeit at low frequencies. Recovered fluorescence of fibrillarin-GFP in nucleoli and CBs after photobleaching indicates that it is highly mobile in both organelles (estimated diffusion constant approximately 0.02 microm(2) s(-1)), and has a significantly larger mobile fraction in CBs than in nucleoli.
    Preview · Article · Nov 2000 · The Journal of Cell Biology
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