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Biomedical subjects

W Joba

Publications and source records attributed to W Joba.

22 records · Page 2Linked to original sources
PubMed1997

Detection and modulation of interleukin-1 receptor antagonist messenger ribonucleic acid and immunoreactivity in Graves' orbital fibroblasts.

PURPOSE: To analyze the expression and regulation of intracellular and soluble interleukin-1 (IL-1) receptor antagonist (IL-1RA) in orbital fibroblasts and to determine whether a disbalance between IL-1 receptor agonist and antagonist may promote IL-1 mediated proinflammatory actions in Graves' ophthalmopathy (GO). METHODS: Early passages of cultured orbital fibroblasts (OFs) derived from four patients with active GO and six control subjects were examined for their baseline expression of the two variants of IL-1RA, intracellular IL-1RA (icIL-1RA) and soluble IL-1ra (sIL-1RA. In addition, modulation of icIL-1RA and sIL-1RA was studied after exposure of OF to a broad range of cytokines as well as to nonspecific stimulating agents such as lipopolysaccharide and phorbol-12-myristate 13-acetate. The IL-1RA gene and protein variants were analyzed by reverse transcriptase-polymerase chain reaction, immunocytochemical staining, immunoblotting, and enzyme-linked immunosorbent assay. RESULTS: At baseline, both GO- and control OF showed low levels of constitutive icIL-1RA ribonucleic acid and absence of sIL-1RA ribonucleic acid expression. Exposure to various cytokines stimulated icIL-1RA and sIL-1RA gene expression in both groups, but generally to markedly lower levels in GO-OF compared to that of control OF (P < 0.01). Analysis of IL-1RA protein expression showed low levels of constitutive IL-1RA immunoreactivity (22 kDa) in cell lysates and absence of sIL-1RA immunoreactivity in culture supernatants derived from both GO-OF and control OF. Interleukin-1-alpha was capable of inducing expression of two variants (23 and 26 kDa) of IL-1RA immunoreactivity in supernatants, derived from control OF, and to a lesser degree, GO-OF (P < 0.01). Quantitative analysis showed markedly lower abundance of IL-1RA immunoreactivity in cell lysates and supernatants derived from GO-OF monolayers compared to that detected in control OF (P < 0.001). CONCLUSIONS: Our results demonstrate differences in regulation of icIL-1RA and sIL-1RA and markedly lower levels of expression in cultured GO-OF compared to normal OF. Failure to generate, upon cytokine stimulation, sufficient quantities of icIL-1RA and sIL-1RA to balance agonist stimulation of the IL-1 receptor may facilitate IL-1-dependent proinflammatory and fibrogenic actions within the orbital tissue in GO.

Cell Culture Techniques↗
PubMed1996

Alternative splicing of repetitive units is responsible for the polydispersities of integumentary mucin B.1 (FIM-B.1) from Xenopus laevis.

Frog integumentary mucin B.1 (FIM-B.1) represents a polymorphic extracellular mosaic protein which contains tandemly arranged serine/threonine-rich modules as well as cysteine-rich domains. The latter are probably important for oligomerization of FIM-B.1 and have also been found in many proteins of the complement cascade as well as regions homologous to von Willebrand factor. The repetitive modules are targets for extensive O-glycosylation. Previous cDNA cloning experiments clearly established polydispersities within the same individual, which originate from deletions/insertions in the repetitive domain. Here, we analyse part of the corresponding genomic region. Each repetitive unit as well as the cysteine-rich domain is encoded by an individual class 1-1 exon typical of shuffled modules. Alternative splicing of these multiple cassettes creates the polydisperse FIM-B.1 transcripts.

Alternative Splicing↗
PubMed1992

The polymorphic integumentary mucin B.1 from Xenopus laevis contains the short consensus repeat.

The frog integumentary mucin B.1 (FIM-B.1), discovered by molecular cloning, contains a cysteine-rich C-terminal domain which is homologous with von Willebrand factor. With the help of the polymerase chain reaction, we now characterize a contiguous region 5' to the von Willebrand factor domain containing the short consensus repeat typical of many proteins from the complement system. Multiple transcripts have been cloned, which originate from a single animal and differ by a variable number of tandem repeats (rep-33 sequences). These different transcripts probably originate solely from two genes and are generated presumably by alternative splicing of an huge array of functional cassettes. This model is supported by analysis of genomic FIM-B.1 sequences from Xenopus laevis. Here, rep-33 sequences are arranged in an interrupted array of individual units. Additionally, results of Southern analysis revealed genetic polymorphism between different animals which is predicted to be within the tandem repeats. A first investigation of the predicted mucins with the help of a specific antibody against a synthetic peptide determined the molecular mass of FIM-B.1 to greater than 200 kDa. Here again, genetic polymorphism between different animals is detected.

Amino Acid Sequence↗