Immunolocalisation and partial characterization of a nuclear autoantigen (PM-Scl) associated with polymyositis/scleroderma overlap syndrome. J Immunol

The Journal of Immunology (Impact Factor: 4.92). 01/1987; 137(12):3802-8.
Source: PubMed


Precipitating anti-PM-Scl antibodies are present in sera from patients with polymyositis, scleroderma, and polymyositis/scleroderma overlap syndromes. By indirect immunofluorescence microscopy, anti-PM-Scl antibodies stained the nucleolus in cells of different tissues and species, suggesting that the antigen is highly conserved. By electron microscopy, anti-PM-Scl antibodies reacted primarily with the granular component of the nucleolus. Drugs that inhibit rRNA synthesis had a marked effect on the expression of PM-Scl antigen. In actinomycin D-treated cells, immunofluorescence staining by anti-PM-Scl was significantly reduced with residual staining restricted to the granular regions of nucleoli. Treatment with 5,6-dichloro-beta-D-ribofuranosylbenzimidazole (DRB) also selectively reduced nucleolar staining. On a molecular level, anti-PM-Scl antibodies precipitated 11 polypeptides with molecular weights (Mr) ranging from 110,000 to 20,000. The Mr 80,000 and 20,000 polypeptides were phosphorylated. Evidence suggests that the PM-Scl antigen complex may be related to a preribosomal particle.

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Available from: Eng M Tan
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    • "In previous studies, the human immune response targeting the PM/Scl complex has been reported to be predominantly directed against two polypeptides with apparent molecular masses of 100 kDa and 75 kDa [15]. In the past it has been shown that nearly all PM/Scl-positive sera contain autoantibodies to the 100 kDa protein and that only about 50–60% react with the 75 kDa protein [7,8,15-17]. A more recent study has shown that the PM/Scl-75 protein contains a previously unidentified N-terminal region that is important for the antigenicity of the protein [18]. "
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    ABSTRACT: Anti-PM/Scl antibodies represent a specific serological marker for a subset of patients with scleroderma (Scl) and polymyositis (PM), and especially with the PM/Scl overlap syndrome (PM/Scl). Anti-PM/Scl reactivity is found in 24% of PM/Scl patients and is found in 3-10% of Scl and PM patients. The PM/Scl autoantigen complex comprises 11-16 different polypeptides. Many of those proteins can serve as targets of the anti-PM/Scl B-cell response, but most frequently the PM/Scl-100 and PM/Scl-75 polypeptides are targeted. In the present study we investigated the clinical relevance of a major alpha helical PM/Scl-100 epitope (PM1-alpha) using a newly developed peptide-based immunoassay and compared the immunological properties of this peptide with native and recombinant PM/Scl antigens. In a technical comparison, we showed that an ELISA based on the PM1-alpha peptide is more sensitive than common techniques to detect anti-PM/Scl antibodies such as immunoblot, indirect immunofluorescence on HEp-2 cells and ELISA with recombinant PM/Scl polypeptides. We found no statistical evidence of a positive association between anti-PM1-alpha and other antibodies, with the exception of known PM/Scl components. In our cohort a negative correlation could be found with anti-Scl-70 (topoisomerase I), anti-Jo-1 (histidyl tRNA synthetase) and anti-centromere proteins. In a multicenter evaluation we demonstrated that the PM1-alpha peptide represents a sensitive and reliable substrate for the detection of a subclass of anti-PM/Scl antibodies. In total, 22/40 (55%) PM/Scl patients, 27/205 (13.2%) Scl patients and 3/40 (7.5%) PM patients, but only 5/288 (1.7%) unrelated controls, tested positive for the anti-PM1-alpha peptide antibodies. These data indicate that anti-PM1-alpha antibodies appear to be exclusively present in sera from PM/Scl patients, from Scl patients and, to a lesser extent, from PM patients. The anti-PM1-alpha ELISA thus offers a new serological marker to diagnose and discriminate different systemic autoimmune disorders.
    Full-text · Article · Feb 2005 · Arthritis research & therapy
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    • "Although less well characterized than the yeast exosome, the human counterpart has been identified as the PM-Scl particle, a multi-subunit complex recognized by autoimmune sera of patients suffering from polymyositis–scleroderma overlap syndrome (Allmang et al., 1999). This complex, afterwards referred to as the human exosome, was reported to contain 11–16 subunits ranging from 20 to 110 kDa (Reimer et al., 1986; Gelpi et al., 1990). Size-exclusion chromatography of the human exosome complex in a HeLa cell extract indicated that the cytoplasmic complex has a molecular mass of about 700 kDa (Brouwer et al., 2001); the size previously estimated by glycerol density gradient centrifugation was 300–400 kDa (Mitchell et al., 1997). "
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    ABSTRACT: Recent evidence suggests that gene expression may be regulated, at least in part, at post-transcriptional level by factors inducing the extremely rapid degradation of messenger RNAs. These factors include reactions between adenyl-uridyl-rich elements (AREs) of the relevant mRNA and either specific proteins that bind to these elements or exosomes. This review deals with examples of the proteins (AU-rich binding proteins, AUBPs) and exosomes, which have been shown to form complexes with AREs and bring about rapid degradation of the relevant mRNA, and with certain other factors, which protect the RNA from such degradation. The biochemical and physiological factors underlying the stability of messenger RNAs carrying the ARE motifs will be reviewed in the light of their emerging significance for cell physiology, human pathology, and molecular medicine. We also consider the possible application of the results of recent insights into the mechanisms to pharmacological interventions to prevent or cure disorders, especially developmental disorders, which the suppression of gene expression may bring about. Molecular targeting of specific steps in protein degradation by synthetic compounds has already been utilized for the development of pharmacological therapies.
    Full-text · Article · Jun 2003 · Journal of Cellular Physiology
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    • "The particle has been identified recently as the human counterpart of the yeast exosome , whose main function is the processing of 5.8s rRNA [45] [46]. Patients suffering from the polymyositis/scleroderma overlap syndrome (24%), myositis (8%), and scleroderma (3%) develop this antibody specificity [43] [44] [47] [48]. "
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    ABSTRACT: The characterization of autoantibody specificities in rheumatic diseases is important in both diagnostic and basic research areas. Identification of the epitopes recognized by autoantibodies and their clinical and biological significance is not a trivial task. Epitopes may range in complexity from simple linear sequences of amino acids to complex quaternary structures. In addition to this structural complexity the frequency with which an autoantigen and its epitopes are recognized in a patient population may be useful in diagnosis, defining disease subgroups, and may offer information on disease prognosis. In this review recent advances in the epitope mapping of autoantigens in connective tissue diseases are discussed, with particular emphasis placed on the methodologies used to identify epitopes and the classification of the structural features of epitopes. To illustrate the identification of epitope structure, clinically relevant autoantigens, including CENP-A, PM/Scl-100, fibrillarin, filaggrin, Ro-52, and dsDNA, are discussed as examples of each type of epitope.
    Full-text · Article · Jun 2003 · Clinical Immunology
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