Molecular mechanisms mediating vascular calcification: Role of matrix Gla protein
ABSTRACT Patients with chronic kidney disease (CKD) have a higher incidence of vascular calcification and a greatly increased risk of cardiovascular death. The mechanisms involved in the accelerated vascular calcification observed in CKD have recently become clearer, leading to the hypothesis that a lack of natural inhibitors of calcification may trigger calcium deposition. One of these inhibitory factors, matrix Gla protein (MGP), is the focus of the present review. MGP, originally isolated from bone, is a vitamin K-dependent protein that is also highly expressed by vascular smooth muscle cells. MGP has been confirmed as a calcification-inhibitor in numerous studies; however, its mechanism of action is not completely understood. It potentially acts in several ways to regulate calcium deposition including: (i) binding calcium ions and crystals; (ii) antagonizing bone morphogenetic protein and altering cell differentiation; (iii) binding to extracellular matrix components; and (iv) regulating apoptosis. Its expression is regulated by several factors including retinoic acid, vitamin D and extracellular calcium ions, and a reduced form of vitamin K (KH2) is important in maintaining MGP in an active form. Therefore, strategies aimed at increasing its expression and activity may be beneficial in tipping the balance in favour of inhibition of calcification in CKD.
- SourceAvailable from: Alireza Khabazi[Show abstract] [Hide abstract]
ABSTRACT: Background Imbalanced Matrix Gla protein (MGP) and Osteoprotegerin (OPG) levels occur in inflammatory diseases. Aim of the work The aim of the present study was to evaluate serum MGP and OPG levels in Rheumatoid Arthritis (RA) patients and study their relation to the disease activity. Patients and methods Forty-five female RA patients and 45 age and sex-matched healthy controls were included in this study. Disease activity score 28-C-reactive protein (DAS28-CRP) was used for the assessment of disease activity. High-sensitivity C-reactive protein (hs-CRP), erythrocyte sedimentation rate (ESR), MGP and OPG were measured in patients and controls. The associations of MGP and OPG with DAS28-CRP and the other laboratory and clinical variables were analyzed. Results RA patients had significantly higher serum OPG levels (408.3 ± 520.9 pg/ml) and hs-CRP (2.8 ± 1.9 mg/l) than the control (92.5 ± 86.3 pg/ml and 0.9 ± 1.5 mg/l respectively) (p < 0.001 each). There was no significant difference in MGP levels between the patients and control (p = 0.3). The correlation of OPG and MGP with DAS28-CRP in the patients was insignificant (p = 0.4 and p = 0.8 respectively). Age positively correlated with OPG (r = 0.32, p = 0.02), but not with MGP concentration (r = 0.05, p = 0.64) in the RA patients. Conclusions The significant elevation of the OPG level in RA patients may through light on its possible role in the pathogenesis of this disease and could be considered as a future therapeutic target. The significant correlation with age suggests that OPG may be an important mediator especially in elderly RA cases.07/2014; 36(3). DOI:10.1016/j.ejr.2014.01.003
- [Show abstract] [Hide abstract]
ABSTRACT: The accumulation of senescent cells within tissues can potentially lead to biological dysfunction and manifestation of disease associated with ageing. The majority of senescent cells display a commonly altered secretome similar to a wound healing response (termed the senescence-associated secretory phenotype or SASP), which could have deleterious implications on the tissue microenvironment. However, senescent cells also appear to have a cell-type (or even cell-strain) exclusive senescent phenotype (CESP), an area of research that is underexplored. One such CESP is the pro-calcificatory phenotype recently reported in senescent vascular smooth muscle cells (VSMCs). Senescent VSMCs have been shown to overexpress genes and proteins (including RUNX-2, alkaline phosphatase (ALP), type I collagen and BMP-2) associated with osteoblasts, leading to partial osteoblastic transdifferentiation. As such, it has been suggested that senescent VSMCs contribute to cardiovascular dysfunction through induction of vascular calcification. This review discusses recent findings on VSMC senescence and their potential role in the pathophysiology of vascular calcification.Experimental gerontology 11/2010; 45(11):819-24. DOI:10.1016/j.exger.2010.07.005 · 3.53 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Inhibitor of differentiation-4 is highly expressed in glioblastoma multiforme (GBM). We report a novel pro-angiogenic function for inhibitor of differentiation-4 in the growth of glioblastoma xenografts. Tumor-derived cell cultures expressing elevated levels of ID4 produced enlarged xenografts in immunosuppressed mice that were better vascularized than corresponding control tumors and expressed elevated matrix GLA protein (MGP) that mediated enhanced tumor angiogenesis. Inhibition of MGP resulted in smaller and less vascularized xenografts. Our finding shows a novel function for ID4 in tumor angiogenesis, and identifies ID4 and MGP as possible therapeutic targets for GBM.Oncogene 05/2010; 29(26):3793-802. DOI:10.1038/onc.2010.147 · 8.56 Impact Factor