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RhoA Determines Lineage Fate of MSCs by Modulating CTGF-VEGF Complex in Extracellular Matrix

ABSTRACT: Mesenchymal stem cells (MSCs) participate in the repair/remodeling of many tissues, where MSCs commit to different lineages dependent on the cues in the local microenvironment. Here we show that TGFβ-activated RhoA/ROCK functions as a molecular switch regarding the fate of MSCs in arterial repair/remodeling after injury. MSCs differentiate into myofibroblasts when RhoA/ROCK is turned on, endothelial cells when turned off. The former is pathophysiologic resulting in intimal hyperplasia, whereas the latter is physiological leading to endothelial repair. Further analysis revealed that MSC RhoA activation promotes formation of an extracellular matrix (ECM) complex consisting of connective tissue growth factor (CTGF) and vascular endothelial growth factor (VEGF). Inactivation of RhoA/ROCK in MSCs induces matrix metalloproteinase-3-mediated CTGF cleavage, resulting in VEGF release and MSC endothelial differentiation. Our findings uncover a novel mechanism by which cell-ECM interactions determine stem cell lineage specificity and offer additional molecular targets to manipulate MSC-involved tissue repair/regeneration.

ORGANISM(S): Mus musculus

PROVIDER: GSE73557 | GEO | 2016/03/01

SECONDARY ACCESSION(S): PRJNA297328

REPOSITORIES: GEO

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Project description:Mesenchymal stem cells (MSCs) participate in the repair/remodeling of many tissues, where MSCs commit to different lineages dependent on the cues in the local microenvironment. Here we show that TGFÎ²-activated RhoA/ROCK functions as a molecular switch regarding the fate of MSCs in arterial repair/remodeling after injury. MSCs differentiate into myofibroblasts when RhoA/ROCK is turned on, endothelial cells when turned off. The former is pathophysiologic resulting in intimal hyperplasia, whereas the latter is physiological leading to endothelial repair. Further analysis revealed that MSC RhoA activation promotes formation of an extracellular matrix (ECM) complex consisting of connective tissue growth factor (CTGF) and vascular endothelial growth factor (VEGF). Inactivation of RhoA/ROCK in MSCs induces matrix metalloproteinase-3-mediated CTGF cleavage, resulting in VEGF release and MSC endothelial differentiation. Our findings uncover a novel mechanism by which cell-ECM interactions determine stem cell lineage specificity and offer additional molecular targets to manipulate MSC-involved tissue repair/regeneration. Mouse bone marrow MSCs were purchased from Texas A&M Health Science Center College of Medicine Institute for Regenerative Medicine. All MSCs were cultured in Î±MEM supplied with 10% FCS. The transfection of DNA plasmids were performed with LipofectamineÂ® LTX with Plus Reagent (Life Technologies). Myc-L63RhoA or empty vector (control) was transfected into mouse bone marrow MSCs. Three days later, the cells were harvested and total RNA was isolated using RNeasy Mini kit (Qiagen). A total of four independent experiments were performed. RNA samples were assessed for quality and integrity using Synergy HT (Biotek, Winooski, VT). Microarray expression profiles were generated using the Illumina MouseRef-8 v2.0 Expression BeadChip (Illumina, San Diego, CA). Biotin-labeled cRNA was synthesized by the total prep RNA amplification kit from Ambion (Austin, TX). cRNA was quantified and normalized to 75 ng/Âµl, and then 1Âµg was hybridized to Beadchips. The hybridized chip was scanned using the Illumina iScan system and background corrected signal intensities were extracted using the GenomeStudio software (Illumina). The lumi R package was used to transform the data using a Variance Stabilizing Transformation (VST) and normalized using quantile normalization. Differential expression analysis was performed using the R/Mannova package. P-values were calculated by performing 1000 permutations, then corrected for multiple comparisons by false-discovery rate (FDR) transformation, using a 20% FDR cutoff.

Project description:The small GTPase RhoA regulates a variety of cellular processes, including cell motility, proliferation, survival and permeability. In addition, there are reports suggesting that the RhoA-ROCK axis plays a role in VEGF-mediated angiogenesis, whereas other work has shown opposite effects. To elucidate this conflicting data, we examined HUVEC and HCAEC after stable overexpression (lentiviral transduction) of constitutively active (G14V/Q63L), dominant-negative (T19N), or wild-type RhoA using a variety of in vitro angiogenesis assays (proliferation, migration, tube formation, angiogenic sprouting, endothelial cell viability) and a HUVEC xenograft assay in immune incompetent NSGTM mice in vivo. We observed that expression of active as well as wild-type RhoA but not expression of dominant-negative RhoA significantly increased endothelial cell death as well as inhibited endothelial cell proliferation, migration, tube formation and angiogenic sprouting of endothelial cells in vitro and reduced HUVEC-related angiogenesis in vivo. Inhibition of RhoA by C3 transferase antagonized inhibitory RhoA effects and strongly enhanced VEGF-induced angiogenic sprouting in control-treated cells. In contrast, inhibition of RhoA effectors ROCK1/2 and LIMK1/2 had no significant effect on RhoA-related effects, but again increased angiogenic sprouting and migration of control-treated cells. In line with these data, VEGF did not activate RhoA in HUVEC as measured by a FRET-based biosensor. Furthermore, global transcriptome and subsequent bioinformatic gene ontology (GO) enrichment analyses revealed that constitutively active RhoA induces a differentially expressed gene pattern that is enriched for GO biological process terms such as mitotic nuclear division, cell proliferation, cell motility and cell adhesion and includes a significant decrease in VEGFR-2 and NOS3 expression. Thus, our data demonstrate that increased RhoA activity has the potential to trigger endothelial dysfunction and anti-angiogenic effects independently of its well-characterized downstream effectors ROCK and LIMK.

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RhoA Determines Lineage Fate of MSCs by Modulating CTGF-VEGF Complex in Extracellular Matrix

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