α5β1 integrin induces the expression of noncartilaginous procollagen gene expression in articular chondrocytes cultured in monolayers

INTRODUCTION: Articular chondrocytes undergo an obvious phenotypic change when cultured in monolayers. During this change, or dedifferentiation, the expression of type I and type III procollagen is induced where normal chondrocytes express little type I and type III procollagen. In this study, we attempted to determine the mechanism(s) for the induction of such procollagen expression in dedifferentiating chondrocytes. METHODS: All experiments were performed using primary-cultured human articular chondrocytes under approval of institutional review boards. Integrin(s) responsible for the induction of type I and type III procollagen expression were specified by RNAi experiments. The signal pathway(s) involved in the induction were determined by specific inhibitors and RNAi experiments. Adenovirus-mediated experiments were performed to identify a small GTPase regulating the activity of integrins in dedifferentiating chondrocytes. The effect of inhibition of integrins on dedifferentiation was investigated by experiments using echistatin, a potent disintegrin. The effect of echistatin was investigated first with monolayer-cultured chondrocytes, and then with pellet-cultured chondrocytes. RESULTS: In dedifferentiating chondrocytes, α5β1 integrin was found to be involved in the induction of type I and type III procollagen expression. The induction was known to be mediated by v-akt murine thymoma viral oncogene homolog (AKT) signaling. Among the three AKT isoforms, AKT1 seemed to be most involved in the signaling. Elated RAS viral (r-ras) oncogene homolog (RRAS) was considered to regulate the progression of dedifferentiation by modulating the affinity and avidity of α5β1 integrin to ligands. Echistatin inhibited dedifferentiation of monolayer-cultured chondrocytes. Furthermore, the matrix formed by pellet-cultured chondrocytes more closely resembled that of normal cartilage compared with the controls. CONCLUSIONS: The result of this study has shown, for the first time, that α5β1 integrin may be responsible for the induction of non-cartilaginous collagen expression in chondrocytes undergoing dedifferentiation. Again, this study has shown that the inhibition of ligand ligation to integrins may be an effective strategy to inhibit phenotypic change of cultured chondrocytes, and to improve the quality of matrix synthesized by primary cultured chondrocytes

RESEARCH Open Access

Overexpression of regenerating gene Iα appears to reflect aberration of crypt cell compartmentalization in sessile serrated adenoma/polyps of the colo

Effects of Arabidopsis Ku80 deletion on the integration of the left border of T-DNA into plant chromosomal DNA via Agrobacterium tumefaciens

T-DNA integration into plant chromosomal DNA via Agrobacterium tumefaciens can be achieved by exploiting the double-strand break repair system of the host’s DNA. However, the detailed mechanism of T-DNA integration remains unclear. Here, a sequence analysis of the junction sequences of T-DNA and chromosomal DNA was performed to assess the mechanism of T-DNA integration. T-DNA was introduced into Arabidopsis wild-type and NHEJ-deficient ku80-mutant plants using the floral dip method; the junctions of the left border (LB) of T-DNA were subsequently analyzed by adapter PCR. The most frequent junction of the LB of T-DNA to chromosomal DNA (LB-to-ChrDNA) was of the filler DNA type in both lines. The lengths of direct or inverted repeat sequences within or around the filler DNA sequence were longer in the ku80 mutant. In addition, the frequency of T-DNA integration near the transcription start site was significantly higher in the ku80 mutant. Our observations suggest that the presence of the Ku80 protein affects the location of the integration of T-DNA and the pattern of the formation of repeat sequences within or around the filler DNA during LB integration into chromosomal DNA

An adult patient with Henoch-Schönlein purpura and non-occlusive mesenteric ischemia

<p>Abstract</p> <p>Background</p> <p>Onset of Henoch-Schönlein purpura (HSP) in middle age is uncommon, and adults with renal or gastrointestinal involvement present with more severe disease than do similar pediatric patients.</p> <p>Case presentation</p> <p>We present the case of a 69-year-old male with HSP who, after treatment with steroids, cyclophosphamide, and continuous intravenous prostaglandin E1 (PGE1), died as a result of severe gastrointestinal involvement with non-occlusive mesenteric ischemia (NOMI). Vascular narrowing associated with the NOMI improved after catheter injection of PGE1 and prednisolone, but the patient died of bleeding from an exposed small vessel. At autopsy there was no active vasculitis in the jejunal submucosa.</p> <p>Conclusion</p> <p>Treatment with PGE1 and prednisolone might improve small-vessel vasculitis associated with NOMI.</p