Abnormal angiogenesis and vascular remodeling contribute to pathogenesis of a number of disorders such as tumor, arthritis, atherosclerosis, restenosis, hypertension, and neurodegeneration. During angiogenesis and vascular remodeling, behaviors of stem/progenitor cells, endothelial cells (ECs), and vascular smooth muscle cells (VSMCs) and its interaction with extracellular matrix (ECM) play a critical role in the processes. Matrix metalloproteinases (MMPs), well-known inflammatory mediators are a family of zinc-dependent proteolytic enzymes that degrade various components of ECM and non-ECM molecules mediating tissue remodeling in both physiological and pathological processes. MMPs including MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-12, and MT1-MMP, are stimulated and activated by various stimuli in vascular tissues. Once activated, MMPs degrade ECM proteins or other related signal molecules to promote recruitment of stem/progenitor cells and facilitate migration and invasion of ECs and VSMCs. Moreover, vascular cell proliferation and apoptosis can also be regulated by MMPs via proteolytically cleaving and modulating bioactive molecules and relevant signaling pathways. Regarding the importance of vascular cells in abnormal angiogenesis and vascular remodeling, regulation of vascular cell behaviors through modulating expression and activation of MMPs shows therapeutic potential.

Accumulating evidence suggest that numerous microRNAs (miRNAs) play important roles in cell proliferation, apoptosis, and differentiation, as well as various diseases that accompany inflammatory responses. Inflammation is known to be a major contributor to atherogenesis. Previous studies provide promising evidence in support of the role of miRNAs in cardiovascular disease. However, mechanistic data on these small molecules in atherosclerosis (AS) are still missing. The present study aims to investigate the potential role of miRNAs in AS. The miRNA transcriptase was verified by TaqMan real-time polymerase chain reaction assay. Thoracic aorta samples were obtained from Apolipoprotein E knockout mice, and plasma samples were from coronary artery disease (CAD) patients. The results showed that the miR-155 level was the most significantly elevated both in AS mice and CAD patients relative to the normal control. The functional role of miR-155 in the atherosclerotic path physiological process was also observed in vivo and in vitro. The observations suggested that miR-155 is a part of a negative feedback loop, which down-modulates inflammatory cytokine production and decreases AS progression. miR-155 was also found to mediate the inflammatory response and mitogen-activated protein kinase (MAPK) pathway by targeting mitogen-activated protein kinase kinase kinase 10. miR-155 contributes to the prevention of AS development and progression. It may also be involved in the posttranscriptional regulation of the inflammatory response and MAPK pathway by targeting mitogen-activated protein kinase kinase kinase 10.

Background: Myocardial infarction (MI) elicits cardiac fibroblast activation and extracellular matrix (ECM) deposition to maintain the structural integrity of the heart. Recent studies demonstrate that Fap (fibroblast activation protein)—a prolyl-specific serine protease—is an important marker of activated cardiac fibroblasts after MI. Methods: Left ventricle and plasma samples from patients and healthy donors were used to analyze the expression level of FAP and its prognostic value. Echocardiography and histological analysis of heart sections were used to analyze cardiac functions, scar formation, ECM deposition and angiogenesis after MI. RNA-Sequencing, biochemical analysis, cardiac fibroblasts (CFs) and endothelial cells co-culture were used to reveal the molecular and cellular mechanisms by which Fap regulates angiogenesis. Results: We found that Fap is upregulated in patient cardiac fibroblasts after cardiac injuries, while plasma Fap is downregulated and functions as a prognostic marker for cardiac repair. Genetic or pharmacological inhibition of Fap in mice significantly improved cardiac function after MI. Histological and transcriptomic analyses showed that Fap inhibition leads to increased angiogenesis in the peri-infarct zone, which promotes ECM deposition and alignment by cardiac fibroblasts and prevents their overactivation, thereby limiting scar expansion. Mechanistically, we found that BNP (brain natriuretic peptide) is a novel substrate of Fap that mediates postischemic angiogenesis. Fap degrades BNP to inhibit vascular endothelial cell migration and tube formation. Pharmacological inhibition of Fap in Nppb (encoding pre-proBNP) or Npr1 (encoding the BNP receptor)-deficient mice showed no cardioprotective effects, suggesting that BNP is a physiological substrate of Fap. Conclusions: This study identifies Fap as a negative regulator of cardiac repair and a potential drug target to treat MI. Inhibition of Fap stabilizes BNP to promote angiogenesis and cardiac repair.

Reactive oxygen species (ROS) are derived from the metabolism of oxygen and are traditionally viewed as toxic byproducts that cause damage to biomolecules. It is now becoming widely acknowledged that ROS are key modulators in a variety of biological processes and pathological states. ROS mediate key signaling transduction pathways by reversible oxidation of certain signaling components and are involved in the signaling of growth factors, G-protein-coupled receptors, Notch, and Wnt and its downstream cascades including MAPK, JAK-STAT, NF-κB, and PI3K/AKT. Vascular formation and development is one of the most important events during embryogenesis and is vital for postnasal tissue repair. In this paper, we will discuss how ROS regulate different steps in vascular development, including smooth muscle cell differentiation, angiogenesis, endothelial progenitor cells recruitment, and vascular cell migration.

BACKGROUND: Myocardial infarction (MI) elicits mitochondria reactive oxygen species (ROS) production and cardiomyocyte (CM) apoptosis. Nrf3 (nuclear factor erythroid 2-related factor 3) has an established role in regulating redox signaling and tissue homeostasis. Here, we aimed to evaluate the role and mechanism of Nrf3 in injury-induced pathological cardiac remodeling. METHODS: Global (Nrf3-KO) and CM-specific (Nrf3 ^△CM ) Nrf3 knockout mice were subjected to MI or ischemia/reperfusion injury, followed by functional and histopathological analysis. Primary neonatal mouse and rat ventricular myocytes and CMs derived from human induced pluripotent stem cells were used to evaluate the impact of Nrf3 on CM apoptosis and mitochondrial ROS production. Chromatin immunoprecipitation sequencing and immunoprecipitation–mass spectrometry analysis were used to uncover potential targets of Nrf3. MitoParaquat administration and CM-specific adeno-associated virus vectors were used to further confirm the i n vivo relevance of the identified signal pathways. RESULTS: Nrf3 was expressed mainly in CMs in healthy human hearts, and an increased level of Nrf3 was observed in CMs within the border zone of infarcted human hearts and murine cardiac tissues after MI. Both global and CM-specific Nrf3 knockout significantly decreased injury-induced mitochondrial ROS production, CM apoptosis, and pathological cardiac remodeling, consequently improving cardiac functions. In addition, cardiac-specific Nrf3 overexpression reversed the ameliorative cardiac phenotypes observed in Nrf3-KO mice. Functional studies showed that Nrf3 promoted neonatal mouse ventricular myocyte, neonatal rat ventricular myocyte, and CMs derived from human induced pluripotent stem cell apoptosis by increasing mitochondrial ROS production. Critically, augmenting mitochondrial ROS with MitoParaquat blunted the beneficial effects of Nrf3 deletion on cardiac function and remodeling. Mechanistically, a redox regulator Pitx2 (paired-like homeodomain transcription factor 2) was identified as one of the main target genes of Nrf3. Specifically, Nrf3 binds to Pitx2 promoter, where it increases DNA methylation through recruiting heterogeneous nuclear ribonucleoprotein K and DNA-methyltransferase 1 complex, thereby inhibiting Pitx2 expression. CM-specific knockdown of Pitx2 blunted the beneficial effects of Nrf3 deletion on cardiac function and remodeling, and cardiac-specific Pitx2 overexpression attenuated MI-induced mitochondrial ROS production and CM apoptosis, as well as preserved cardiac functions after MI. CONCLUSIONS: Nrf3 promotes injury-induced CM apoptosis and deteriorates cardiac functions by increasing mitochondrial ROS production through suppressing Pitx2 expression. Targeting the Nrf3–Pitx2–mitochondrial ROS signal axis may therefore represent a novel therapeutic approach for MI treatment.

To investigate the functional involvements of heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) in smooth muscle cell (SMC) differentiation from stem cells, embryonic stem cells were cultivated on collagen IV-coated plates to allow for SMC differentiation. We found that hnRNPA1 gene and protein expression was upregulated significantly during differentiation and coexpressed with SMC differentiation markers in the stem cell-derived SMCs as well as embryonic SMCs of 12.5 days of mouse embryos. hnRNPA1 knockdown resulted in downregulation of smooth muscle markers and transcription factors, while enforced expression of hnRNPA1 enhanced the expression of these genes. Importantly, knockdown of hnRNPA1 also resulted in impairment of SMC differentiation in vivo. Moreover, we demonstrated that hnRNPA1 could transcriptionally regulate SMC gene expression through direct binding to promoters of Acta2 and Tagln genes using luciferase and chromatin immunoprecipitation assays. We further demonstrated that the binding sites for serum response factor (SRF), a well-investigated SMC transcription factor, within the promoter region of the Acta2 and Tagln genes were responsible for hnRNPA1-mediated Acta2 and Tagln gene expression using in vitro site-specific mutagenesis and luciferase activity analyses. Finally, we also demonstrated that hnRNPA1 upregulated the expression of SRF, myocyte-specific enhancer factor 2c (MEF2c), and myocardin through transcriptional activation and direct binding to promoters of the SRF, MEF2c, and Myocd genes. Our findings demonstrated that hnRNPA1 plays a functional role in SMC differentiation from stem cells in vitro and in vivo. This indicates that hnRNPA1 is a potential modulating target for deriving SMCs from stem cells and cardiovascular regenerative medicine.