Annexin V and terminal differentiation of growth plate chondrocytes.
ABSTRACT Terminal differentiation and mineralization are the final events in endochondral bone formation and allow the replacement of cartilage by bone. Retinoic acid (RA) stimulates these events, including upregulation of expression and activity of alkaline phosphatase (APase), expression of annexins II, V, and VI proteins, which bind to membranes and form Ca(2+) channels, expression of osteocalcin and runx2, another mineralization-related protein and terminal differentiation-related transcription factor, and ultimately mineralization. Chelating cytosolic Ca(2+) with BAPTA-AM, interfering with annexin Ca(2+) channel activities using K-201, a specific annexin Ca(2+) channel blocker, or suppression of annexin V expression using siRNA inhibited these events. Overexpression of annexin V in embryonic chicken growth plate chondrocytes resulted in an increase of cytoplasmic Ca(2+) concentration, [Ca(2+)](i) similar to [Ca(2+)](i) increase in RA-treated cultures. Overexpression of annexin V also resulted in upregulation of annexin II, annexin VI, osteocalcin, and runx2 gene expression, expression and activity of APase, and ultimately stimulation of mineralization. K-201 inhibited upregulation of osteocalcin and runx2 gene expression, APase expression and activity, and mineralization in annexin V-overexpressing growth plate chondrocytes. These findings indicate that annexins II, V, and VI alter Ca(2+) homeostasis in growth plate chondrocytes thereby regulating terminal differentiation and mineralization events. Overexpression of annexin V is sufficient to stimulate these terminal differentiation events in growth plate chondrocytes, whereas suppression of annexin V expression inhibits these events.
Revue du Rhumatisme 02/2007; 74(2):168-172. DOI:10.1016/j.rhum.2006.12.001
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ABSTRACT: The present work evaluates the biocompatibility of a fluoride surface-modified AZ31 magnesium alloy (AZ31HF) with different cell lines that coexist in the implant environment to test its potential use as a biodegradable and absorbable biomaterial for bone repair. A clear stimulation of cell proliferation and an enhancement of the mitochondrial respiratory activity were observed when mouse osteoblasts (MC3T3-E1), fibroblasts (L929), and macrophages (J774) cell lines were cultured with the modified alloy. No significant change in apoptosis or viability rates was observed when osteoblasts and fibroblasts cultures were grown in the presence of this alloy. A proteomic analysis of the MC3T3-E1 cell extracts cultured in the presence of AZ31HF showed an overexpression of proteins related with the mineralization process, which is a necessary step for bone repair. An increase in the lactate dehydrogenase activity was observed in the MC3T3-E1 and J774 cell cultures that could be a response of the oxidative stress produced by the presence of the material. This stress could be related to the increase observed in the respiratory mitochondrial activity or respiratory burst measured in theses cultures that indicate damage in the cell membranes and subsequently some cell death. Results reported here, for and against AZ31HF, should be taken into account when considering the potential use of this modified alloy in bone repair applications. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: Appl Biomater, 2013.Journal of Biomedical Materials Research Part A 10/2013; 101(10). DOI:10.1002/jbm.a.34579 · 2.83 Impact Factor
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ABSTRACT: Objective To address the shortcomings of urine cytology and cystoscopy for screening and grading of urinary bladder cancer (BC) we applied a serum-based proteomics approach as a surrogate tactic for rapid BC probing. Methods This study was performed on 90 sera samples comprising of low-grade (LG, n = 33) and high-grade (HG, n = 32) BC, and healthy controls (HC, n = 25). Two-dimensional gel electrophoresis (2DE) tactic was executed to describe serum proteome. MALDI-TOF-MS (MS) was used to identify the characteristics of aberrantly expressed proteins in 2DE and validated using Western blot (WB) and ELISA approach. Receiver operating characteristics (ROC) curve analysis was also performed to determine the clinical usefulness of these proteins to discriminate among LG, HG and HC cohorts. Results This comprehensive approach of 2DE, MS, WB and ELISA reveals five differentially expressed proteins. Among them two biomarkers (S100A8 and S100A9) were able to accurately (ROC, 0.946) distinguish 81% of BC (LG + HG) cases compared to HC with highest sensitivity and specificity. With a comparable tactic, two biomarkers (S100A8 and S100A4) were able to precisely (ROC, 0.941) discriminate 92% of LG cases from HG with utmost sensitivity and specificity. Conclusions Serum proteomics probing appears to be an encouraging and least-invasive tactic for screening and grading of BC.Clinica Chimica Acta 09/2014; 436:97–103. DOI:10.1016/j.cca.2014.05.012 · 2.76 Impact Factor