Project description:Vascular calcification is a complex process and has been associated with aging, diabetes, chronic kidney disease (CKD). Although there have been several studies studying the role of miRNAs (miRs) in bone osteogenesis, little is known about the role of miRs in vascular calcification and their role in the pathogenesis of vascular abnormalities. Matrix vesicles (MV) are known to play an important role in initiating vascular smooth muscle cell (VSMC) calcification. In the present study, we performed miRNA microarray analysis to identify the dysregulated miRs between MV and VSMC derived from CKD rats to understand the role of post-transcriptional regulatory networks governed by these miRNAs in vascular calcification and to uncover the differential miRNA content of MV. The percentage of miRNA to total RNA was increased in MV compared to VSMC. Comparison of expression profiles of miRNA by microarray demonstrated 33 miRs to be differentially expressed with the majority (~ 57%) of them down-regulated. Target genes controlled by differentially expressed miRNAs were identified utilizing two different complementary computational approaches Miranda and Targetscan to understand the functions and pathways that may be affected due to the production of MV from calcifying VSMC thereby contributing to the regulation of genes by miRs. We found several processes including vascular smooth muscle contraction, response to hypoxia and regulation of muscle cell differentiation to be enriched. Signaling pathways identified included MAP-kinase and wnt signaling that have previously been shown to be important in vascular calcification. In conclusion, our results demonstrate that miRs are concentrated in MV from calcifying VSMC, and that important functions and pathways are affected by the miRs dysregulation between calcifying VSMC and the MV they produce. This suggests that miRs may play a very important regulatory role in vascular calcification in CKD by controlling an extensive network of post-transcriptional targets. Compare miRNA from matrix vesicles to miRNA from vascular smooth muscle cells that gave rise to the matrix vesicles from 3 sets of MV and VSMC derived from 3 normal and 3 CKD rats

Project description:Background: Ectopic vascular calcifications represent a major clinical problem associated with cardiovascular disease and mortality. However, the mechanisms underlying pathological vascular calcifications are largely unknown hampering the development of therapies to tackle this life threatening medical condition. Results: In order to gain insight into the genes and mechanisms driving this pathological calcification process we analyzed the transcriptional profile of calcifying vascular smooth muscle cells (C-VSMCs). These profiles were compared to differentiating osteoblasts, cells that constitute their physiological calcification counterparts in the body. Overall the transcriptional program of C-VSMC and osteoblasts did not overlap. Several genes, some of them relevant for bone formation, were distinctly modulated by C-VSMCs which did not necessarily lose their smooth muscle cell markers while calcifying. Bioinformatics gene clustering and correlation analysis disclosed limited bone-related mechanisms being shared by two cell types. Extracellular matrix (ECM) and biomineralization genes represented common denominators between pathological vascular and physiological bone calcifications. These genes constitute the strongest link between these cells and represent potential drivers for their shared end-point phenotype. Conclusions: the analyses support the hypothesis that VSMC trans-differentiate into C-VSMCs keeping their own identity while using mechanisms that osteoblasts use to mineralize. The data provide novel insights into groups of genes and biological processes shared in MSC and VSMC osteogenic differentiation. The distinct gene regulation between C-VSMC and osteoblasts might hold clues to find cell-specific pathway modulations, opening the possibility to tackle undesired vascular calcifications without disturbing physiologic bone formation and vice versa. Total RNA obtained from hMSC and hVSMC cultured in osteogenic differentiation medium supplemented with 1.8 mM Ca2+ for 0, 2, 8, 12 or 25 days respectively. For each timepoint 3 replicates were used, with exception for day 0 where 4 replicates were collected.

Project description:Vascular calcification is a complex process and has been associated with aging, diabetes, chronic kidney disease (CKD). Although there have been several studies studying the role of miRNAs (miRs) in bone osteogenesis, little is known about the role of miRs in vascular calcification and their role in the pathogenesis of vascular abnormalities. Matrix vesicles (MV) are known to play an important role in initiating vascular smooth muscle cell (VSMC) calcification. In the present study, we performed miRNA microarray analysis to identify the dysregulated miRs between MV and VSMC derived from CKD rats to understand the role of post-transcriptional regulatory networks governed by these miRNAs in vascular calcification and to uncover the differential miRNA content of MV. The percentage of miRNA to total RNA was increased in MV compared to VSMC. Comparison of expression profiles of miRNA by microarray demonstrated 33 miRs to be differentially expressed with the majority (~ 57%) of them down-regulated. Target genes controlled by differentially expressed miRNAs were identified utilizing two different complementary computational approaches Miranda and Targetscan to understand the functions and pathways that may be affected due to the production of MV from calcifying VSMC thereby contributing to the regulation of genes by miRs. We found several processes including vascular smooth muscle contraction, response to hypoxia and regulation of muscle cell differentiation to be enriched. Signaling pathways identified included MAP-kinase and wnt signaling that have previously been shown to be important in vascular calcification. In conclusion, our results demonstrate that miRs are concentrated in MV from calcifying VSMC, and that important functions and pathways are affected by the miRs dysregulation between calcifying VSMC and the MV they produce. This suggests that miRs may play a very important regulatory role in vascular calcification in CKD by controlling an extensive network of post-transcriptional targets.

Project description:Vascular Calcification (VC) is a life threatening cardiovascular complication that accounts for high death rates particularly in association with diabetes, atherosclerosis and Chronic Kidney Disease (CKD. during VC, Vascular Smooth Muscle Cells (VSMCs) undergo reprogramming into osteoblast-like cells in response to calcium and phosphate mineral imbalance in CKD patients. This osteogenic switch is driven by the expression of several bone markers such as Runt- related transcription factor 2 (Runx2), Alkaline Phosphatase (ALP), Osteopontin (OPN), Matrix-Gla Protein (MGP), Osteocalcin (OCN), Type I Collagen (COL1), and Bone Sialo Proteins (BSPs). Recent studies showed that VSMCs secrete heterogeneous populations of Extracellular Vesicles (EVs)11 that are enriched under physiological conditions by calcification inhibitors such as Fetuin-A and MGP12,13,14. Interestingly, under pathological conditions, secreted EVs have a pro-calcifying profile and thereby act as nucleating foci for hydroxyapatite crystallization and propagation11,15. Electron Microscopy based studies revealed that EVs were embedded between collagen and elastin fibrils of arterial walls suggesting that calcification can be initiated through the EVs’ direct physical interaction with them13,16. We previously showed that a specific oligogalacturonic acid with a degree of polymerization of 8 (DP8) was able to inhibit vascular calcification. This inhibition was partly due to a decrease of osteogenic markers’s expression but also to the masking of a consensus sequence found in COL1 i.e. GFOGER sequence, thus preventing EVs from binding to COL1. Although the use of DP8 in-vivo seems to be compromised due to probable enzymatic digestion, these results suggested that the inhibition of VSMCs’ osteogenic switch and the prevention of EVs-COL1 interaction could represent new potential therapeutic targets for inhibiting VC17. Since we have already showed that the triple-helical GFOGER consensus sequence forms a preferential binding site for EVs17, we thereby chemically synthesized a GFOGER peptide in order to determine its ability to inhibit VC on VSMCs and on an aortic ring ex-vivo model. We also aim to decipher the mechanisms of inhibition by investigating the osteogenic markers’ expression as well as the protein content of secreted EVs in the presence of the GFOGER peptide.

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To examine vascular smooth muscle cells (VSMC) under four conditions

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