Project description:Arterial smooth muscle cells (ASMCs) undergo phenotypic changes during development and pathological processes in vivo and during cell culture in vitro. Our previous studies demonstrated that retrovirally-mediated expression of the versican V3 splice variant (V3) that lacks glycosaminoglycan chains by ASMCs retards cell proliferation and migration in vitro and reduces neointimal thickening, macrophage and lipid accumulation in animal models of vascular injury and atherosclerosis. However, the molecular pathways induced by V3 expression that are responsible for these changes are not yet clear. In the present study, we employed a microarray approach to examine how expression of V3 induced changes in gene expression and the molecular pathways in ASMCs. We found that forced expression of V3 by ASMCs affected expression of 521 genes by more than 1.5 fold. Gene ontology (GO) analysis shows that components of extracellular matrix were the most significantly affected by V3 expression, indicating that V3 expression elicits profound remodeling of extracellular matrix. In addition, genes regulating the formation of the cytoskeleton which also serve as markers of contractile smooth muscle cells were significantly upregulated. On the other hand, components of the complement system, chemokines, chemokine receptors, and transcription factors crucial for regulating inflammatory processes were among the genes most downregulated. Consistently, we found that the level of myocardin, a key transcription factor promoting contractile ASMC phenotype, was greatly increased while proinflammatory transcription factors NFkappaB1 and C/EBPβ were significantly attenuated in V3-expressing SMCs. Such results indicate that V3 expression reprograms ASMC into differentiated and anti-inflammatory phenotypes. Overall, these findings demonstrate that expression of V3 reprograms ASMCs promoting anti-inflammatory and differentiated smooth muscle cell phenotypes potentially by altering cell-ECM interaction and focal adhesion signaling pathways. Fischer rat ASMCs were transduced with either a retroviral vector expressing the Versican V3 splice variant (LV3SN) or an empty control vector (LXSN) in three independent experiments. In the first experiment, V3 and control transductions were performed with four technical replicates. In the subsequent two experiments, individual transductions were done for the V3 or control treatments. For data analysis, the technical replicates from the first experiment were averaged, and then data from the three experiments was evaluated in a paired manner.

Project description:Arterial smooth muscle cells (ASMCs) undergo phenotypic changes during development and pathological processes in vivo and during cell culture in vitro. Our previous studies demonstrated that retrovirally-mediated expression of the versican V3 splice variant (V3) that lacks glycosaminoglycan chains by ASMCs retards cell proliferation and migration in vitro and reduces neointimal thickening, macrophage and lipid accumulation in animal models of vascular injury and atherosclerosis. However, the molecular pathways induced by V3 expression that are responsible for these changes are not yet clear. In the present study, we employed a microarray approach to examine how expression of V3 induced changes in gene expression and the molecular pathways in ASMCs. We found that forced expression of V3 by ASMCs affected expression of 521 genes by more than 1.5 fold. Gene ontology (GO) analysis shows that components of extracellular matrix were the most significantly affected by V3 expression, indicating that V3 expression elicits profound remodeling of extracellular matrix. In addition, genes regulating the formation of the cytoskeleton which also serve as markers of contractile smooth muscle cells were significantly upregulated. On the other hand, components of the complement system, chemokines, chemokine receptors, and transcription factors crucial for regulating inflammatory processes were among the genes most downregulated. Consistently, we found that the level of myocardin, a key transcription factor promoting contractile ASMC phenotype, was greatly increased while proinflammatory transcription factors NFkappaB1 and C/EBPβ were significantly attenuated in V3-expressing SMCs. Such results indicate that V3 expression reprograms ASMC into differentiated and anti-inflammatory phenotypes. Overall, these findings demonstrate that expression of V3 reprograms ASMCs promoting anti-inflammatory and differentiated smooth muscle cell phenotypes potentially by altering cell-ECM interaction and focal adhesion signaling pathways.

Project description:Smooth muscle cells (SMCs) are important in a number of physiological systems and organs, including the cardiovascular system. The hallmark property of differentiated SMCs is the ability to contract, but contractile SMCs themselves show a range of phenotypes allowing prolonged tonic contraction in vascular smooth muscle or rapid phasic contraction in tissues such as bladder. Another distinctive characteristic, in contrast with terminally differentiated striated muscle cells, is that SMCs exhibit phenotypic plasticity. Vascular SMCs are able to modulate their phenotype along a continuum between a contractile phenotype, characteristic of healthy blood vessels, and a more proliferative âsyntheticâ phenotype, so-named for the enhanced synthesis and secretion of extracellular matrix components. Synthetic phenotype cells are found in a number of pathological situations such as atherosclerosis and arterial injury. We used mouse exon-junction (MJAY) arrays to gain insights into both the global contribution of alternative splicing events in re-shaping the transcriptome of dedifferentiating mouse aorta and bladder SMCs, and into the underlying regulatory mechanisms of the alternative splicing program. Affymetrix splice junction arrays (MJAY) were used to profile changes in both alternative splicing and transcript levels during the phenotypic modulation of smooth muscle cells when placed in culture. RNA extracted from intact aorta and bladder smooth muscle tissue was used for differentiated samples. For dedifferentiated, proliferative samples smooth muscle cells were enzymatically dispersed and grown in tissue culture for a week. Triplicate RNA samples were prepared from smooth muscle tissue of mouse aorta and bladder (differentiated) and from smooth muscle cells from each tissue cultured for 7 days (proliferative). The samples allowed comparison of alternative splicing (and other transcriptome) changes between differentiated and proliferative smooth muscle cell samples from two distinct types of smooth muscle cell, as well as allowing direct comparison of aorta (tonic smooth muscle) and bladder (phasic smooth muscle).

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