ABSTRACT
Sox9 is a transcription factor that is critical for chondrogenesis, testis determination, and development of several other organs in vertebrates. Thus the levels of Sox9 protein and its activity may be tightly regulated. Here we show that inhibitors of the 26S proteasome increase both the levels of Sox9 protein and its transcriptional activity measured with Col2a1 promoter/enhancer construct in RCS cells and C3H10T1/2 cells. Indeed, in intact cells ubiquitination assays indicate that Sox9 is multiply ubiquitinated. The K398A mutation, which was introduced in a potential ubiquitin-binding site, increases the stability of Sox9 protein and its transcriptional activity of Col2a1, Col11a2, and AMH promoter/enhancer constructs without affecting the subcellular localization and the DNA binding efficiency of Sox9. Pulse-chase experiments show that the increased Sox9 levels resulting from treatment with the MG132 proteasome inhibitor or from the K398A mutation produce stabilization of the protein. Our in vitro studies indicate that the ubiquitin-proteasome proteolytic system degrades Sox9 and regulates its transcriptional activity.
Subject(s)
High Mobility Group Proteins/genetics , High Mobility Group Proteins/metabolism , Proteasome Endopeptidase Complex/chemistry , Transcription Factors/genetics , Transcription Factors/metabolism , Ubiquitin/chemistry , Animals , Binding Sites , Blotting, Western , COS Cells , Cell Line, Tumor , Cells, Cultured , Chondrocytes/metabolism , Collagen Type II/genetics , Enhancer Elements, Genetic , High Mobility Group Proteins/chemistry , Humans , Mice , Mice, Inbred C3H , Microscopy, Fluorescence , Mutation , Promoter Regions, Genetic , Proteasome Endopeptidase Complex/metabolism , Proteasome Inhibitors , Protein Structure, Tertiary , Rats , SOX9 Transcription Factor , Time Factors , Transcription Factors/chemistry , Transcription, Genetic , Transfection , Ubiquitin/metabolismABSTRACT
BACKGROUND: Helicobacter pylori is an established cause of gastritis and has been implicated in extradigestive diseases. OBJECTIVE: To investigate the role of H. pylori in patients with unexplained refractory pruritus. METHODS: Ten patients with severe pruritus unresponsive to conventional therapy were evaluated for active H. pylori infection by H. pylori serology followed by either esophagogastroduodenoscopy (EGD) or urea breath test. Of the 10 patients, 8 were found to have active infection. All 10 received anti-H. pylori antibiotic therapy and were reevaluated for relief of pruritus. RESULTS: Of 8 patients with active H. pylori infection, 87.5% (7/8) had some type of pruritus relief after triple therapy. Of these, 62.5% (5/8) had complete relief and 25% (2/8) had temporary relief of pruritus. The remaining 12.5% (1/8) did not respond. Two control patients without active H. pylori infection had no relief of pruritus with therapy. CONCLUSIONS: We have identified a population of patients with refractory pruritus and active H. pylori infection whose pruritus resolved after eradication of H. pylori.
