Targeting the platelet-derived growth factor signalling in cardiovascular disease

Necrotic Change of Tunica Media Plays a Key Role in the Development of Coronary Artery Lesions in Kawasaki Disease

BACKGROUND

Alarmins resulting from cell death or oxidative stress are involved in the development of Kawasaki disease (KD) vasculitis. In a previous study, we demonstrated the potential role of interleukin (IL)-33 as an alarmin in the development of KD vasculitis. Although edematous dissociation (necrotic change) of the tunica media is thought to be a major source of IL-33 in KD vasculitis, it has not yet been elucidated.

METHODS AND RESULTS

We investigated the impact of IL-33 released from necrotic human coronary artery smooth muscle cells (HCASMCs) on human coronary artery endothelial cells (HCAECs) using a coculture assay. Subsequently, we evaluated the anti-inflammatory effects of anti-IL-33 and anti-suppression of tumorigenicity 2 (ST2) antibodies compared with conventional therapies of KD, such as high-dose IgG or anti-tumor necrosis factor (TNF)-α antibody. Primary necrosis of HCASMCs induced significant release of IL-33. In cocultures of necrotic HCASMCs with HCAECs, the necrotic HCASMCs significantly induced the production of various proinflammatory cytokines in the HCAECs. Anti-IL-33 and anti-ST2 antibodies exhibited unique inhibitory effects on the production of platelet-derived growth factor-BB or IL-12(p70) in HCAECs.

CONCLUSIONS

There is potential involvement of edematous dissociation of the tunica media in the development of KD vasculitis. Furthermore, the distinctive anti-inflammatory effects of the anti-IL-33/ST2 axis drugs suggest novel therapeutic options for patients with refractory KD.

ERRα: unraveling its role as a key player in cell migration

Cell migration is essential throughout the life of multicellular organisms, and largely depends on the spatial and temporal regulation of cytoskeletal dynamics, cell adhesion and signal transduction. Interestingly, Estrogen-related receptor alpha (ERRα) has been identified as a major regulator of cell migration in both physiological and pathological conditions. ERRα is an orphan member of the nuclear hormone receptor superfamily of transcription factors and displays many biological functions. ERRα is a global regulator of energy metabolism, and it is also highly involved in bone homeostasis, development, differentiation, immunity and cancer progression. Importantly, in some instances, the regulation of these biological processes relies on the ability to orchestrate cell movements. Therefore, this review describes how ERRα-mediated cell migration contributes not only to tissue homeostasis but also to tumorigenesis and metastasis, and highlights the molecular and cellular mechanisms by which ERRα finely controls the cell migratory potential.

Inhibition of p90RSK Ameliorates PDGF-BB-Mediated Phenotypic Change of Vascular Smooth Muscle Cell and Subsequent Hyperplasia of Neointima

Platelet-derived growth factor type BB (PDGF-BB) regulates vascular smooth muscle cell (VSMC) migration and proliferation, which play critical roles in the development of vascular conditions. p90 ribosomal S6 kinase (p90RSK) can regulate various cellular processes through many different target substrates in several cell types, but the regulatory function of p90RSK on PDGF-BB-mediated cell migration and proliferation and subsequent vascular neointima formation has not yet been extensively examined. In this study, we investigated whether p90RSK inhibition protects VSMCs against PDGF-BB-induced cellular phenotypic changes and the molecular mechanisms underlying the effect of p90RSK inhibition on neointimal hyperplasia in vivo. Pretreatment of cultured primary rat VSMCs with FMK or BI-D1870, which are specific inhibitors of p90RSK, suppressed PDGF-BB-induced phenotypic changes, including migration, proliferation, and extracellular matrix accumulation, in VSMCs. Additionally, FMK and BI-D1870 repressed the PDGF-BB-induced upregulation of cyclin D1 and cyclin-dependent kinase-4 expression. Furthermore, p90RSK inhibition hindered the inhibitory effect of PDGF-BB on Cdk inhibitor p27 expression, indicating that p90RSK may induce VSMC proliferation by regulating the G0/G1 phase. Notably, treatment with FMK resulted in attenuation of neointima development in ligated carotid arteries in mice. The findings imply that p90RSK inhibition mitigates the phenotypic switch and neointimal hyperplasia induced by PDGF-BB.

Molecular mechanisms of coronary artery disease risk at the PDGFD locus

Genome wide association studies for coronary artery disease (CAD) have identified a risk locus at 11q22.3. Here, we verify with mechanistic studies that rs2019090 and PDGFD represent the functional variant and gene at this locus. Further, FOXC1/C2 transcription factor binding at rs2019090 is shown to promote PDGFD transcription through the CAD promoting allele. With single cell transcriptomic and histology studies with Pdgfd knockdown in an SMC lineage tracing male atherosclerosis mouse model we find that Pdgfd promotes expansion, migration, and transition of SMC lineage cells to the chondromyocyte phenotype. Pdgfd also increases adventitial fibroblast and pericyte expression of chemokines and leukocyte adhesion molecules, which is linked to plaque macrophage recruitment. Despite these changes there is no effect of Pdgfd deletion on overall plaque burden. These findings suggest that PDGFD mediates CAD risk by promoting deleterious phenotypic changes in SMC, along with an inflammatory response that is primarily focused in the adventitia.

Angiogenetic transcriptional profiling reveals potential targets modulated in blood of patients with cardiovascular disorders

OBJECTIVES

Based on the angiogenetic, transcriptional profile of non-diseased and arteriosclerotic vessels, we aim to identify the leucocytic markers as a potential, minimal invasive tool supporting diagnosis of vascular pathology.

METHODS

Transcriptional profiling was performed with Angiogenesis RT² Profiler PCR (Polymerase Chain Reaction) array on three non-pathological and three arteriosclerotic vessels, followed by immunohistochemical staining. Based on these screening results, selected transcripts were employed for qPCR with specific primers and investigated on the blood RNA (RiboNucleic Acid) obtained from nine healthy controls and 29 patients with cardiovascular disorders. Thereafter, expression of these transcripts was investigated in vitro in human monocytes under calcification-mimicking conditions.

RESULTS AND CONCLUSIONS

Transcriptional profiling on the vessels revealed that out of 84 targets investigated two were up-regulated more than 100-fold, 18 more than 30 and 15 more than 10, while the most noticeable down-regulation was observed by ephrin-A3 and platelet-derived growth factor alpha (PDGFA) genes. Based on the vessel results, investigations of the selected blood transcripts revealed that thrombospondin 1 (THBS1), thrombospondin 3 (THBS3), transforming growth factor, beta receptor 1 (TGFBR1), platelet-derived growth factor alpha, plasminogen activator, urokinase (PLAU) and platelet/endothelial cell adhesion molecule 1 (PECAM-1) were significantly elevated in cardiovascular blood as compared to corresponding controls. Induction of calcification-related conditions in vitro to human THP-1 monocytes led to noticeable modulation of these transcripts. Taken together, these data demonstrate that leucocytic THBS1, THBS3, TGFBR1, platelet-derived growth factor alpha, PLAU and PECAM-1 have a correlation with cardiovascular disorders and could be used as a supportive tool predicting development of this pathological condition.

Molecular mechanisms of coronary artery disease risk at the PDGFD locus

Platelet derived growth factor (PDGF) signaling has been extensively studied in the context of vascular disease, but the genetics of this pathway remain to be established. Genome wide association studies (GWAS) for coronary artery disease (CAD) have identified a risk locus at 11q22.3, and we have verified with fine mapping approaches that the regulatory variant rs2019090 and PDGFD represent the functional variant and putative functional gene. Further, FOXC1/C2 transcription factor (TF) binding at rs2019090 was found to promote PDGFD transcription through the CAD promoting allele. Employing a constitutive Pdgfd knockout allele along with SMC lineage tracing in a male atherosclerosis mouse model we mapped single cell transcriptomic, cell state, and lesion anatomical changes associated with gene loss. These studies revealed that Pdgfd promotes expansion, migration, and transition of SMC lineage cells to the chondromyocyte phenotype and vascular calcification. This is in contrast to protective CAD genes TCF21, ZEB2, and SMAD3 which we have shown to promote the fibroblast-like cell transition or perturb the pattern or extent of transition to the chondromyocyte phenotype. Further, Pdgfd expressing fibroblasts and pericytes exhibited greater expression of chemokines and leukocyte adhesion molecules, consistent with observed increased macrophage recruitment to the plaque. Despite these changes there was no effect of Pdgfd deletion on SMC contribution to the fibrous cap or overall lesion burden. These findings suggest that PDGFD mediates CAD risk through promoting SMC expansion and migration, in conjunction with deleterious phenotypic changes, and through promoting an inflammatory response that is primarily focused in the adventitia where it contributes to leukocyte trafficking to the diseased vessel wall.

The protective role of EP300 in monocrotaline-induced pulmonary hypertension

Background

Pulmonary hypertension (PH) is a lethal disease characterized by pulmonary vascular remodeling, which is mediated by the abnormal proliferation/migration of pulmonary arterial smooth muscle cells (PASMCs). Recent reports suggest the involvement of histone acetylation in PAH development and that histone deacetylase (HDAC) inhibitors have therapeutic potential for the treatment of PAH. EP300 is an acetyltransferase that plays diverse roles in cell proliferation, differentiation, and apoptosis. However, the functions of EP3000 in PH are rarely studied.

Results

In this work, we found that the expression of EP300 was increased in the pulmonary arteries of monocrotaline (MCT)-induced PH rats. Knockdown of EP300 by AAV-mediated shRNA exacerbated the PH, with a higher right ventricular systolic pressure (RVSP), right ventricular hypertrophy index (RVHI), and wall thickness in the pulmonary artery of MCT-induced PH rat. On the cellular level, the proliferation of PASMCs was promoted by EP300 knockdown. In addition, the expression of EP300 was increased in PASMCs by the overexpression of EGR1, while the deletion of EGR1 binding sites in the EP300 promoter region decreased the activity of EP300 promoter. Moreover, deleting the EP300 promoter region containing EGR1 binding sites using CRISPR/Cas9 abolished the upregulation of EP300 in MCT-induced rats and exacerbated MCT-induced PH. To summarize, our data indicate that EP300 upregulation mediated by EGR1 has a protective effect on MCT-induced PH.

Conclusion

These findings showed EP300 expression was increased in the MCT-induced PH model in rats, which could be mediated by EGR1; the EP300 also displayed the potential to provide protection from PH.

Hyperglycemic conditions induce rapid cell dysfunction-promoting transcriptional alterations in human aortic endothelial cells

Hyperglycemia is a major risk factor in the development of diabetic complications and promotes vascular complications through dysregulation of endothelial cell function. Various mechanisms have been proposed for endothelial cell dysregulation but the early transcriptomic alterations of endothelial cells under hyperglycemic conditions are not well documented. Here we use deep time-series RNA-seq profiling of human aortic endothelial cells (HAECs) following exposure to normal (NG) and high glucose (HG) conditions over a time course from baseline to 24 h to identify the early and transient transcriptomic changes, alteration of molecular networks, and their temporal dynamics. The analysis revealed that the most significant pathway activation/inhibition events take place in the 1- to 4-h transition and identified distinct clusters of genes that underlie a cascade of coordinated transcriptional events unique to HG conditions. Temporal co-expression and causal network analysis implicate the activation of type 2 diabetes (T2D) and growth factor signalling pathways including STAT3 and NF-κB. These results document HAEC transcriptional changes induced by hyperglycemic conditions and provide basic insight into the rapid molecular alterations that promote endothelial cell dysfunction.

Role of platelet-derived growth factor c on endothelial dysfunction in cardiovascular diseases

Loss of endothelial function is a common feature to all cardiovascular diseases (CVDs). One of the risk factors associated with the development of CVDs is the hyperglycaemia that occurs in patients with metabolic disorders such as Type 1 and Type 2 diabetes mellitus. Hyperglycaemia causes endothelial dysfunction through increased production of reactive oxygen species (ROS) from different cellular sources leading to oxidative stress. Vascular endothelial growth factor (VEGF) is essential in the stimulation and maintenance of endothelial functional aspects and, although it can mitigate the impact of ROS, VEGF-mediated signalling is partially inhibited in diabetes mellitus. The search for therapeutic strategies that preserve, protect and improve the functions of the endothelium is of great relevance in the investigation of CVDs associated with hyperglycaemia. Platelet-derived growth factor C (PDGF-C) is a peptide with angiogenic properties, independent of VEGF, that stimulates angiogenesis and revascularization of ischemic tissue. In a diabetic mouse model, PDGF-C stimulates mature endothelial cell migration, angiogenesis, endothelial progenitor cell mobilization, and increased neovascularization, and protects blood vessels in a retinal degeneration model activating anti-apoptosis and proliferation signalling pathways in endothelial cells. This review summarizes the information on the damage that high d-glucose causes on endothelial function and the beneficial effects that PDGF-CC could exert in this condition.

The effect of short-term intensive insulin therapy on inflammatory cytokines in patients with newly diagnosed type 2 diabetes

BACKGROUND

Diabetes mellitus was a chronic low-grade inflammatory disease and had increased circulating inflammatory cytokines and acute phase proteins. We aimed to identify the changes of inflammatory cytokines in newly diagnosed type 2 diabetic patients after short-term intensive insulin therapy using continuous subcutaneous insulin infusion (CSII).

METHODS

Thirty-three newly diagnosed type 2 diabetic patients were enrolled between September 2020 to December 2020. Expression of 40 inflammatory cytokines of the patients were tested with RayBiotech antibody array before and after 1 week of intensive insulin therapy of CSII. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was carried out to explore the signaling pathway involved in the therapy.

RESULTS

Five inflammatory cytokines were downregulated significantly after 1 week of CSII therapy. They were interleukin-6 receptor (IL-6R), regulated upon activation normal T-cell expressed and secreted (RANTES), intercellular adhesion molecule-1 (ICAM-1), tissue inhibitor of metalloproteinase-1 (TIMP-1), and platelet-derived growth factor type BB (PDGF-BB) (p < 0.05 and foldchange <0.83). Among patients with baseline glycated hemoglobin (HbA1c) < 10%, three proinflammatory cytokines were decreased significantly after therapy: IL-6R, RANTES, and ICAM-1. As for the patients with baseline HbA1c ≥ 10%, eight inflammatory cytokines were inhibited significantly after the treatment, including ICAM-1, IL-6R, RANTES, TIMP-1, TIMP-2, macrophage inflammatory protein-1 beta (MIP-1β), PDGF-BB, and tumor necrosis factor receptor type II (TNF RII). No matter which subgroup of baseline HbA1c level was considered, the decreased cytokines after CSII therapy were significantly involved in TNF signaling pathway. Nuclear factor-kappa B (NF-κB) signaling pathway was mainly enriched in patients with baseline HbA1c ≥ 10%.

CONCLUSIONS

A panel of 40 inflammatory cytokines, measured by protein microarray, were evaluated for 1 week of CSII treatment in newly diagnosed type 2 diabetic patients. After treatment, many proinflammatory cytokines decreased. In the higher baseline HbA1c subgroup, more proinflammatory cytokines improved. No matter which subgroup of HbA1c level was considered, IL-6R, RANTES, and ICAM-1, which were involved in TNF signaling pathway, decreased significantly after CSII therapy. This was the first report showing that the cytokines of IL-6R, TIMP-2, PDGF-BB, and TNF RII decreased after the CSII therapy.

Skeleton-secreted PDGF-BB mediates arterial stiffening

Evidence links osteoporosis and cardiovascular disease but the cellular and molecular mechanisms are unclear. Here we identify skeleton-secreted platelet-derived growth factor-BB (PDGF-BB) as a key mediator of arterial stiffening in response to aging and metabolic stress. Aged mice and those fed high-fat diet (HFD), relative to young mice and those fed normal chow food diet, respectively, had higher serum PDGF-BB and developed bone loss and arterial stiffening. Bone/bone marrow preosteoclasts in aged mice and HFD mice secrete an excessive amount of PDGF-BB, contributing to the elevated PDGF-BB in blood circulation. Conditioned medium prepared from preosteoclasts stimulated proliferation and migration of the vascular smooth muscle cells. Conditional transgenic mice, in which PDGF-BB is overexpressed in preosteoclasts, had 3-fold higher serum PDGF-BB concentration and developed simultaneous bone loss and arterial stiffening spontaneously at a young age. Conversely, in conditional knockout mice, in which PDGF-BB is deleted selectively in preosteoclasts, HFD did not affect serum PDGF-BB concentration; as a result, HFD-induced bone loss and arterial stiffening were attenuated. These studies confirm that preosteoclasts are a main source of excessive PDGF-BB in blood circulation during aging and metabolic stress and establish the role of skeleton-derived PDGF-BB as an important mediator of vascular stiffening.

The role of PDGF-BB in the bone-vascular relationship during aging

Cardiovascular disease (CVD) and osteoporosis often occur together, suggesting an association between CVD and bone loss. Similarly, the correlation of bone loss, atherosclerosis, and aortic calcification, especially in patients with chronic kidney disease, exemplifies a bone-vessel connection. In this issue of the JCI, Santhanam et al. investigated the role of the angiogenesis factor platelet-derived growth factor-BB (PDGF-BB) in vascular stiffening. Serum levels of bone-derived PDGF-BB differed between young and aged mice, and in mice fed a high-fat diet (HFD) compared with those fed normal chow. Experiments with genetic models led the authors to conclude that bone-derived PDGF-BB mediates the hallmark arterial stiffening of aging and metabolic stress. Notably, excessive preosteoclast-derived PDGF-BB production during aging inhibited osteoblastic bone formation and increased circulating PDGF-BB, which in turn, accelerated vascular stiffness. These findings suggest that modifying circulating PDGF-BB levels may benefit patients with CVD, osteoporosis, and other age-related diseases.

NEAT1 silencing alleviates pulmonary arterial smooth muscle cell migration and proliferation under hypoxia through regulation of miR‑34a‑5p/KLF4 in vitro

Pulmonary arterial hypertension (PAH) is a severe vascular disease that adversely affects patient health and can be life threatening. The present study aimed to investigate the detailed role of nuclear paraspeckle assembly transcript 1 (NEAT1) in PAH. Using RT‑qPCR, the expression levels of NEAT1, microRNA (miR)‑34a‑5p, and Krüppel‑like factor 4 (KLF4) were detected in both hypoxia‑treated pulmonary arterial smooth muscle cells (PASMCs) and serum from PAH patients. Then, the interactions among miR‑34a‑5p, NEAT1, and KLF4 were evaluated by dual‑luciferase reporter assay. The detailed role of the NEAT1/miR‑34a‑5p/KLF4 axis in PAH pathogenesis was further explored using MTT, Transwell, and western blot assays. The results revealed that NEAT1 targeted miR‑34a‑5p and miR‑34a‑5p targeted KLF4. In hypoxia‑treated PASMCs and serum from PAH patients, high NEAT1 and KLF4 expression levels and low miR‑34a‑5p expression were observed. The proliferation and migration of hypoxia‑treated PASMCs were reduced by transfection with sh‑NEAT1 or miR‑34a‑5p mimics. The suppressive effects of NEAT1 knockdown on the proliferation and migration of hypoxia‑treated PASMCs were reversed by knock down of miR‑34a‑5p expression and increased KLF4 expression. NEAT1 was not only highly expressed in the serum of PAH patients but its silencing also alleviated PAH by regulating miR‑34a‑5p/KLF4 in vitro. The present study highlighted a potential new therapeutic target and diagnostic biomarker for PAH.

TMEM98, a novel secretory protein, promotes endothelial cell adhesion as well as vascular smooth muscle cell proliferation and migration

Transmembrane protein 98 (TMEM98) is a novel gene, and its function has not been well investigated. In a prior study, we have shown that siRNA-mediated knockdown of TMEM98 inhibited interleukin-8 (IL-8) promoted endothelial cell (EC) adhesion, as well as vascular smooth muscle cell (VSMC) proliferation and migration in the vascular endothelial and smooth muscle cell dysfunction. Herein, we used gain- and loss-of-function approaches combined with biochemical techniques to further explore the role of TMEM98 in the vascular wall cell. The expression and secretion of TMEM98 was increased in cultured human umbilical vein endothelial cells (HUVECs) and VSMCs treated with IL-8 and platelet-derived growth factor-BB (PDGF-BB). Also, PDGF-BB secretion was increased in TMEM98-treated HUVECs and VSMCs. Thus, it appears that TMEM98 and PDGF-BB form a positive feedback loop in potentiation of EC adhesion, as well as VSMC proliferation and migration. Knockdown of TMEM98 mediated by siRNA inhibited PDGF-BB-promoted EC adhesion by downregulating the expression of ICAM-1 and VCAM-1, as well as impaired the proliferation and migration of VSMCs by suppressing the AKT/GSK3β/cyclin D1 signaling pathway and reducing the expression of β-catenin. Hence, TMEM98 promoted EC adhesion by inducing the expression of ICAM-1/VCAM-1 and triggered VSMC proliferation and migration by activating the ERK and AKT/GSK3β signaling pathways. Taken together, TMEM98 may serve as a potential therapeutic target for the clinical treatment of vascular endothelial and smooth muscle cell dysfunction.

Platelet-Derived Growth Factor Predicts Vulnerable Plaque in Patients with Non-ST Elevation Acute Coronary Syndrome

BACKGROUND

Identifying a novel biomarker may contribute to detection of vulnerable plaque in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS). The aim of this study was to investigate the relationship between serum platelet-derived growth factor (PDGF) and vulnerable plaque in patients with moderate and low risk of NSTE-ACS.

METHODS

A total of 65 moderate- and low-risk NSTE-ACS patients with 50-90% coronary stenosis were divided into a vulnerable plaque group (n=46) and a stable plaque group (n=19) according to intravascular ultrasound (IVUS) examinations. Total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and serum PDGF were measured. Plaque characteristics and components were analyzed using gray-scale and iMap-IVUS. Correlation was performed between plaque characteristics and ACS markers. Logistic regression analysis was applied to determine risk factors. Receiver operating characteristic (ROC) curve was used to evaluate the predictive value.

RESULTS

Patients with vulnerable plaque had visible higher levels of TG, LDL-C and PDGF (P < 0.05). There were significant differences in minimal lumen area (MLA), plaque area, plaque burden, fibrotic (FI), clipidic (LI) and necrotic core (NC) between the two groups (P < 0.05). PDGF was weakly correlated with plaque burden (R = 0.428, P < 0.05), as well as moderately correlated with NC (R = 0.669, P < 0.05). Multivariate analysis showed that serum PDGF (OR 4.751, [95% CI 1.534-9.543], P = 0.05) was an independent risk factor of vulnerable plaque. The area under the curve (AUC) was 0.876 (95% CI 0.804-0.948, P=0.001).

CONCLUSIONS

Serum PDGF could potentially predict vulnerable plaque in moderate and low risk of NSTE-ACS patients.

Microbiota and Metabolites as Factors Influencing Blood Pressure Regulation

The study of microbes has rapidly expanded in recent years due to a surge in our understanding that humans host a plethora of commensal microbes, which reside in their bodies and depending upon their composition, contribute to either normal physiology or pathophysiology. This article provides a general foundation for learning about host-commensal microbial interactions as an emerging area of research. The article is divided into two sections. The first section is dedicated to introducing commensal microbiota and its known effects on the host. The second section is on metabolites, which are biochemicals that the host and the microbes use for bi-directional communication with each other. Together, the sections review what is known about how microbes interact with the host to impact cardiovascular physiology, especially blood pressure regulation. © 2021 American Physiological Society. Compr Physiol 11:1731-1757, 2021.

MicroRNA-520c-3p suppresses vascular endothelium dysfunction by targeting RELA and regulating the AKT and NF-κB signaling pathways

Endothelial injury, which can cause endothelial inflammation and dysfunction, is an important mechanism for the development of atherosclerotic plaque. This study aims to investigate the functional role of miR-520c-3p in vascular endothelium during inflammatory diseases such as atherosclerosis. Quantitative real-time PCR was used to detect miR-520c-3p expression in in human umbilical vein endothelial cells (HUVECs) after treatment with platelet-derived growth factor (PDGF). Furthermore, the effects of miR-520c-3p overexpression and silencing on cell proliferation, adhesion, and apoptosis were assessed. Bioinformatics analysis and Biotin-labeled miRNA pull-down assay were used to confirm the targets of miR-520-3p. Then, the effects of miR-520c-3p on AKT and NF-κB signaling pathways were detected by western blot. Herein, we observed that the expression level of miR-520c-3p was downregulated in HUVECs under PDGF stimulation. Overexpression of miR-520c-3p not only decreased cell adhesion but also promoted proliferation and inhibited apoptosis to protect the viability of endothelial cells. It was confirmed that RELA is the target of miR-520c-3p. MiR-520c-3p inhibited the protein phosphorylation of AKT and RELA, and si-RELA reversed the promotion of AKT and RELA protein phosphorylation by anti-miR-520c-3p. In summary, our study suggested that miRNA-520c-3p targeting RELA through AKT and NF-κB signaling pathways regulated the proliferation, apoptosis, and adhesion of vascular endothelial cells. We conclude that miR-520c-3p may play an important role in the suppression of endothelial injury, which could serve as a biomarker and therapeutic target for atherosclerosis.

Targeting Platelet in Atherosclerosis Plaque Formation: Current Knowledge and Future Perspectives

Besides their role in hemostasis and thrombosis, it has become increasingly clear that platelets are also involved in many other pathological processes of the vascular system, such as atherosclerotic plaque formation. Atherosclerosis is a chronic vascular inflammatory disease, which preferentially develops at sites under disturbed blood flow with low speeds and chaotic directions. Hyperglycemia, hyperlipidemia, and hypertension are all risk factors for atherosclerosis. When the vascular microenvironment changes, platelets can respond quickly to interact with endothelial cells and leukocytes, participating in atherosclerosis. This review discusses the important roles of platelets in the plaque formation under pro-atherogenic factors. Specifically, we discussed the platelet behaviors under disturbed flow, hyperglycemia, and hyperlipidemia conditions. We also summarized the molecular mechanisms involved in vascular inflammation during atherogenesis based on platelet receptors and secretion of inflammatory factors. Finally, we highlighted the studies of platelet migration in atherogenesis. In general, we elaborated an atherogenic role of platelets and the aspects that should be further studied in the future.

Galangin Inhibits LPS-Induced MMP-9 Expression via Suppressing Protein Kinase-Dependent AP-1 and FoxO1 Activation in Rat Brain Astrocytes

Purpose

Neuroinflammation, characterized by the increased expression of inflammatory proteins such as matrix metalloproteinases (MMPs), plays a critical role in neurodegenerative disorders. Lipopolysaccharide (LPS) has been shown to upregulate MMP-9 expression through the activation of various transcription factors, including activator protein 1 (AP-1) and forkhead box protein O1 (FoxO1). The flavonoid 3,5,7-trihydroxy-2-phenyl-4H-1-benzopyran-4-one (galangin) has been demonstrated to possess antioxidant and anti-inflammatory properties in various types of cells. Here, we investigated the mechanisms underlying the inhibitory effect of galangin on LPS-induced MMP-9 expression in rat brain astrocytes (RBA-1 cells).

Methods

Pharmacological inhibitors and siRNAs were employed to explore the effects of galangin on LPS-challenged RBA-1 cells. Gelatin zymography, Western blotting, real-time PCR, and a luciferase reporter assay were used to detect MMP-9 activity, protein expression, mRNA levels, and promoter activity, respectively. The protein kinases involved in the LPS-induced MMP-9 expression were determined by Western blot. A chromatin immunoprecipitation (ChIP) assay was employed to evaluate the activity of c-Jun at the MMP-9 promoter.

Results

Galangin treatment attenuated the LPS-mediated induction of MMP-9 protein and mRNA expression, as well as the activity at the MMP-9 promoter. In addition, galangin exerted its inhibitory effects on MMP-9 expression through suppressing the LPS-stimulated activation of proline-rich tyrosine kinase (Pyk2), platelet-derived growth factor receptor beta (PDGFRβ), phosphoinositide 3-kinase (PI3K), protein kinase B (Akt), mammalian target of rapamycin (mTOR), and mitogen-activated protein kinases (MAPKs). Pretreatment with galangin attenuated the LPS-induced phosphorylation of c-Jun and FoxO1. LPS-induced cell migration was also suppressed by galangin pretreatment.

Conclusion

Galangin attenuates the LPS-induced inflammatory responses, including the induction of MMP-9 expression and cell migration, via inhibiting Pyk2/PDGFRβ/PI3K/Akt/mTOR/JNK1/JNK2 and p44/p42 MAPK cascade-dependent AP-1 and FoxO1 activities. These results provide new insights into the mechanisms through which galangin mitigates LPS-induced inflammatory responses, and suggest novel strategies for the management of LPS-related brain diseases.

Growth factors in pulmonary arterial hypertension: Focus on preserving right ventricular function

Pulmonary arterial hypertension (PAH) is a rare and progressive disease, characterized by increased vascular resistance leading to right ventricle (RV) failure. The extent of right ventricular dysfunction crucially influences disease prognosis; however, currently no therapies have specific cardioprotective effects. Besides discussing the pathophysiology of right ventricular adaptation in PAH, this review focuses on the roles of growth factors (GFs) in disease pathomechanism. We also summarize the involvement of GFs in the preservation of cardiomyocyte function, to evaluate their potential as cardioprotective biomarkers and novel therapeutic targets in PAH.

Role of platelet-derived growth factor in type II diabetes mellitus and its complications

Type 2 diabetes mellitus is a type of metabolic disorder characterized by hyperglycaemia with multiple serious complications, such as diabetic neuropathies, diabetic nephropathy, diabetic retinopathy, and diabetic foot. Platelet-derived growth factors are growth factors that regulate cell growth and division, playing a critical role in diabetes and its harmful complications. This review focused on the cellular mechanism of platelet-derived growth factors and their receptors on diabetes development. Furthermore, we raise some proper therapeutic molecular targets for the treatment of diabetes and its complications.

TIM‑3 inhibits PDGF‑BB‑induced atherogenic responses in human artery vascular smooth muscle cells

Increasing evidence suggests that T-cell immunoglobulin and mucin domain 3 (TIM-3) displays anti-atherosclerotic effects, but its role in vascular smooth muscle cells (VSMCs) has not been reported. The present study aimed to investigate the function of TIM-3 and its roles in human artery VSMCs (HASMCs). A protein array was used to investigate the TIM-3 protein expression profile, which indicated that TIM-3 expression was increased in the serum of patients with lower extremity arteriosclerosis obliterans disease (LEAOD) compared with healthy individuals. Immunohistochemistry and western blotting of arterial tissue further revealed that TIM-3 expression was increased in LEAOD artery tissue compared with normal artery tissue. Additionally, platelet-derived growth factor-BB (PDGF-BB) displayed a positive correlation with TIM-3 expression in HASMCs. TIM-3 decreased the migration and proliferation of PDGF-BB-induced HASMCs, and anti-TIM-3 blocked the effects of TIM-3. The effect of TIM-3 on the proliferation and migration of HASMCs was further investigated using LV-TIM-3-transduced cells. The results revealed that TIM-3 also inhibited PDGF-BB-induced expression of the inflammatory factors interleukin-6 and tumor necrosis factor-α by suppressing NF-κB activation. In summary, the present study revealed that TIM-3 displayed a regulatory role during the PDGF-BB-induced inflammatory reaction in HASMCs, which indicated that TIM-3 may display anti-atherosclerotic effects.

Slug, a Cancer-Related Transcription Factor, is Involved in Vascular Smooth Muscle Cell Transdifferentiation Induced by Platelet-Derived Growth Factor-BB During Atherosclerosis

Background Heart attacks and stroke often result from occlusive thrombi following the rupture of vulnerable atherosclerotic plaques. Vascular smooth muscle cells (VSMCs) play a pivotal role in plaque vulnerability because of their switch towards a proinflammatory/macrophage-like phenotype when in the context of atherosclerosis. The prometastatic transcription factor Slug/Snail2 is a critical regulator of cell phenotypic transition. Here, we aimed to investigate the role of Slug in the transdifferentiation process of VSMCs occurring during atherogenesis. Methods and Results In rat and human primary aortic smooth muscle cells, Slug protein expression is strongly and rapidly increased by platelet-derived growth factor-BB (PDGF-BB). PDGF-BB increases Slug protein without affecting mRNA levels indicating that this growth factor stabilizes Slug protein. Immunocytochemistry and subcellular fractionation experiments reveal that PDGF-BB triggers a rapid accumulation of Slug in VSMC nuclei. Using pharmacological tools, we show that the PDGF-BB-dependent mechanism of Slug stabilization in VSMCs involves the extracellular signal-regulated kinase 1/2 pathway. Immunohistochemistry experiments on type V and type VI atherosclerotic lesions of human carotids show smooth muscle-specific myosin heavy chain-/Slug-positive cells surrounding the prothrombotic lipid core. In VSMCs, Slug siRNAs inhibit prostaglandin E2 secretion and prevent the inhibition of cholesterol efflux gene expression mediated by PDGF-BB, known to be involved in plaque vulnerability and/or thrombogenicity. Conclusions Our results highlight, for the first time, a role of Slug in aortic smooth muscle cell transdifferentiation and enable us to consider Slug as an actor playing a role in the atherosclerotic plaque progression towards a life-threatening phenotype. This also argues for common features between acute cardiovascular events and cancer.

FURIN Inhibition Reduces Vascular Remodeling and Atherosclerotic Lesion Progression in Mice

Objective- Atherosclerotic coronary artery disease is the leading cause of death worldwide, and current treatment options are insufficient. Using systems-level network cluster analyses on a large coronary artery disease case-control cohort, we previously identified PCSK3 (proprotein convertase subtilisin/kexin family member 3; FURIN) as a member of several coronary artery disease-associated pathways. Thus, our objective is to determine the role of FURIN in atherosclerosis. Approach and Results- In vitro, FURIN inhibitor treatment resulted in reduced monocyte migration and reduced macrophage and vascular endothelial cell inflammatory and cytokine gene expression. In vivo, administration of an irreversible inhibitor of FURIN, α-1-PDX (α1-antitrypsin Portland), to hyperlipidemic Ldlr^-/- mice resulted in lower atherosclerotic lesion area and a specific reduction in severe lesions. Significantly lower lesional macrophage and collagen area, as well as systemic inflammatory markers, were observed. MMP2 (matrix metallopeptidase 2), an effector of endothelial function and atherosclerotic lesion progression, and a FURIN substrate was significantly reduced in the aorta of inhibitor-treated mice. To determine FURIN's role in vascular endothelial function, we administered α-1-PDX to Apoe^-/- mice harboring a wire injury in the common carotid artery. We observed significantly decreased carotid intimal thickness and lower plaque cellularity, smooth muscle cell, macrophage, and inflammatory marker content, suggesting protection against vascular remodeling. Overexpression of FURIN in this model resulted in a significant 67% increase in intimal plaque thickness, confirming that FURIN levels directly correlate with atherosclerosis. Conclusions- We show that systemic inhibition of FURIN in mice decreases vascular remodeling and atherosclerosis. FURIN-mediated modulation of MMP2 activity may contribute to the atheroprotection observed in these mice.

Long non-coding RNA SNHG16 regulates human aortic smooth muscle cell proliferation and migration via sponging miR-205 and modulating Smad2

The present study investigated the role of long non‐coding RNA (lncRNA) small nucleolar RNA host gene 16 (SNHG16) in the human aortic smooth muscle cell (HASMC) proliferation and migration and explored the potential link between SNHG16 and atherosclerosis. Our results showed that platelet‐derived growth factor (PDGF)‐bb treatment promoted cell proliferation and migration with concurrent up‐regulation of SNHG16 in HASMCs. Small nucleolar RNA host gene 16 overexpression promoted HASMC proliferation and migration, while SNHG16 knockdown suppressed cell proliferation and migration in PDGF‐bb‐stimulated HASMCs. The bioinformatic analyses showed that SNHG16 possessed the complementary binding sequence with miR‐205, where the interaction was confirmed by luciferase reporter assay and RNA pull‐down assay in HASMCs, and SNHG16 inversely regulated miR‐205 expression. MiR‐205 overexpression attenuated the enhanced effects of PDGF‐bb treatment on HASMC proliferation and migration. Moreover, Smad2 was targeted and inversely regulated by miR‐205, while being positively regulated by SNHG16 in HASMCs. Smad2 knockdown attenuated PDGF‐bb‐mediated actions on HASMC proliferation and migration. Both miR‐205 overexpression and Smad2 knockdown partially reversed the effects of SNHG16 overexpression on HASMC proliferation and migration. Moreover, SNHG16 and Smad2 mRNA were up‐regulated, while miR‐205 was down‐regulated in the plasma from patients with atherosclerosis. Small nucleolar RNA host gene 16 expression was inversely correlated with miR‐205 expression and positively correlated with Smad2 expression in the plasma from atherosclerotic patients. In conclusion, our data showed the up‐regulation of SNHG16 in pathogenic‐stimulated HASMCs and clinical samples from atherosclerotic patients. Small nucleolar RNA host gene 16 regulated HASMC proliferation and migration possibly via regulating Smad2 expression by acting as a competing endogenous RNA for miR‐205.

MicroRNA-92a promotes vascular smooth muscle cell proliferation and migration through the ROCK/MLCK signalling pathway

To identify the interaction between known regulators of atherosclerosis, microRNA-92a (miR-92a), Rho-associated coiled-coil-forming kinase (ROCK) and myosin light chain kinase (MLCK), we examined their expressions during proliferation and migration of platelet-derived growth factor-BB (PDGF-BB)-regulated vascular smooth muscle cells (VSMCs), both in vivo and in vitro. During the formation of atherosclerosis plaque in mice, a parallel increase in expression levels of MLCK and miR-92a was observed while miR-92a expression was reduced in ML-7 (an inhibitor of MLCK) treated mice and in MLCK-deficient VSMCs. In vitro results indicated that both MLCK and miR-92a shared the same signalling pathway. Transfection of miR-92a mimic partially restored the effect of MLCK's deficiency and antagonized the effect of Y27632 (an inhibitor of ROCK) on the down-regulation of VSMCs activities. ML-7 increased the expression of Kruppel-like factor 4 (KLF4, a target of miR-92a), and siRNA-KLF4 increased VSMCs' activity level. Consistently, inhibition of either MLCK or ROCK enhanced the KLF4 expression. Moreover, we observed that ROCK/MLCK up-regulated miR-92a expression in VSMCs through signal transducer and activator of transcription 3 (STAT3) activation. In conclusion, the activation of ROCK/STAT3 and/or MLCK/STAT3 may up-regulate miR-92a expression, which subsequently inhibits KLF4 expression and promotes PDGF-BB-mediated proliferation and migration of VSMCs. This new downstream node in the ROCK/MLCK signalling pathway may offer a potential intervention target for treatment of atherosclerosis.

An Update on the Effects of Glyceollins on Human Health: Possible Anticancer Effects and Underlying Mechanisms

Biologically active plant-based compounds, commonly referred to as phytochemicals, can influence the expression and function of various receptors and transcription factors or signaling pathways that play vital roles in cellular functions and are then involved in human health and diseases. Thus, phytochemicals may have a great potential to prevent and treat chronic diseases. Glyceollins, a group of phytoalexins that are isolated from soybeans, have attracted attention because they exert numerous effects on human functions and diseases, notably anticancer effects. In this review, we have presented an update on the effects of glyceollins in relation to their potential beneficial roles in human health. Despite a growing number of studies suggesting that this new family of phytochemicals can be involved in critical cellular pathways, such as estrogen receptor, protein kinase, and lipid kinase signaling pathways, future investigations will be needed to better understand their molecular mechanisms and their specific significance in biomedical applications.

Nicotinic ACh receptor α7 inhibits PDGF-induced migration of vascular smooth muscle cells by activating mitochondrial deacetylase sirtuin 3

BACKGROUND AND PURPOSE

PDGF-BB is an angiogenic factor involved in cardiovascular diseases. Here, we investigated the possible effects of activation of the nicotinic ACh receptor α7 subtype (α7nAChR) on PDGF-BB-induced proliferation and migration in vascular smooth muscle cells (VSMCs).

EXPERIMENTAL APPROACH

PNU-282987, a selective α7nAChR pharmacological agonist, was used to activate α7nAChR. The influences of α7nAChR activation on PDGF-BB-induced proliferation and migration, as well as the phosphorylation of focal adhesion kinase (FAK)/Src, a pro-migration signalling pathway, were determined in VSMCs. A variety of biochemical assays were applied to explore the underlying molecular mechanisms.

KEY RESULTS

PDGF-BB induced pronounced migration and proliferation of VSMCs. Activation of α7nAChRs by PNU-282987 blocked PDGF-BB-induced migration but not proliferation in wild-type (WT) VSMCs, whereas this effect was absent in α7nAChR-knockout VSMCs. Accordingly, PNU-282987 attenuated PDGF-BB-induced phosphorylation of FAK^Tyr397 and Src^Tyr416 in WT VSMCs. Mechanistically, PNU-282987 suppressed PDGF-BB-induced oxidative stress, as demonstrated by the alterations in ROS, H₂ O₂ content, superoxide anion and total antioxidant activity. A sirtuin 3 (SIRT3) inhibitor 3-(1H-1,2,3-triazol-4-yl) pyridine or shRNA-mediated SIRT3 knockdown abolished the inhibitory effect of PNU-282987. PNU-282987 did not modulate SIRT3 protein expression but enhanced mitochondrial SIRT3 deacetylase activity. In line with this action, PNU-282987 enhanced the deacetylation of mitochondrial FoxO3. Lastly, PNU-282987 corrected the PDGF-BB-induced mitochondrial dysfunction by increasing mitochondrial citrate synthase activity, ATP content and nicotinamide adenine dinucleotide pool.

CONCLUSIONS

Pharmacological activation of α7nAChRs inhibits PDGF-BB-induced VSMC migration by activating the mitochondrial deacetylase SIRT3, implying an important role for α7nAChRs in mitochondria biology and PDGF-related diseases.

LINKED ARTICLES

This article is part of a themed section on Mitochondrial Pharmacology: Featured Mechanisms and Approaches for Therapy Translation. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.22/issuetoc.

PDGF-C and PDGF-D signaling in vascular diseases and animal models

Members of the platelet-derived growth factor (PDGF) family are well known to be involved in different pathological conditions. The cellular and molecular mechanisms induced by the PDGF signaling have been well studied. Nevertheless, there is much more to discover about their functions and some important questions to be answered. This review summarizes the known roles of two of the PDGFs, PDGF-C and PDGF-D, in vascular diseases. There are clear implications for these growth factors in several vascular diseases, such as atherosclerosis and stroke. The PDGF receptors are broadly expressed in the cardiovascular system in cells such as fibroblasts, smooth muscle cells and pericytes. Altered expression of the receptors and the ligands have been found in various cardiovascular diseases and current studies have shown important implications of PDGF-C and PDGF-D signaling in fibrosis, neovascularization, atherosclerosis and restenosis.

Inhibition of PDGF-BB-induced proliferation and migration in VSMCs by proanthocyanidin A2: Involvement of KDR and Jak-2/STAT-3/cPLA2 signaling pathways

Proanthocyanidin A2 (PA2), one of A-type proanthocyanidins, has been shown to harbor a broad spectrum of pharmacological activities, including anti-inflammatory, antioxidant, anti-HIV, anti-CDV and anti-?-glucosidase activities. However, little is known about the role for PA2 in regulating PDGF-induced VSMC proliferation and migration. In the present study, we investigated the possible effects of PA2 on PDGF-BB-induced proliferation, migration and inflammation in VSMCs in vitro to mimic a postangioplasty PDGF shedding condition. Herein, the data clearly show that PA2 markedly inhibited proliferation, migration and inflammatory responses at 0-30??g/ml concentration in VSMCs in vitro. 10-30??g/ml PA2 inhibited PDGF-mediated NAD(P)H oxidase activation and intracellular ROS formation in VSMCs. Furthermore, the effects exerted by PA2 involve the participation of KDR and Jak-2/STAT-3/cPLA₂ signaling pathways. These data also highlight the possible therapeutic use of PA2 in vascular proliferative diseases, where abnormal proliferation and migration play important pathological roles.

Involvement of platelet-derived growth factor ligands and receptors in tumorigenesis

Platelet-derived growth factor (PDGF) isoforms and their receptors have important roles during embryogenesis, particularly in the development of various mesenchymal cell types in different organs. In the adult, PDGF stimulates wound healing and regulates tissue homeostasis. However, overactivity of PDGF signalling is associated with malignancies and other diseases characterized by excessive cell proliferation, such as fibrotic conditions and atherosclerosis. In certain tumours, genetic or epigenetic alterations of the genes for PDGF ligands and receptors drive tumour cell proliferation and survival. Examples include the rare skin tumour dermatofibrosarcoma protuberance, which is driven by autocrine PDGF stimulation due to translocation of a PDGF gene, and certain gastrointestinal stromal tumours and leukaemias, which are driven by constitute activation of PDGF receptors due to point mutations and formation of fusion proteins of the receptors, respectively. Moreover, PDGF stimulates cells in tumour stroma and promotes angiogenesis as well as the development of cancer-associated fibroblasts, both of which promote tumour progression. Inhibitors of PDGF signalling may thus be of clinical usefulness in the treatment of certain tumours.

Platelet-Derived Growth Factor BB Influences Muscle Regeneration in Duchenne Muscle Dystrophy

Duchenne muscular dystrophy (DMD) is characterized by a progressive loss of muscle fibers, and their substitution by fibrotic and adipose tissue. Many factors contribute to this process, but the molecular pathways related to regeneration and degeneration of muscle are not completely known. Platelet-derived growth factor (PDGF)-BB belongs to a family of growth factors that regulate proliferation, migration, and differentiation of mesenchymal cells. The role of PDGF-BB in muscle regeneration in humans has not been studied. We analyzed the expression of PDGF-BB in muscle biopsy samples from controls and patients with DMD. We performed in vitro experiments to understand the effects of PDGF-BB on myoblasts involved in the pathophysiology of muscular dystrophies and confirmed our results in vivo by treating the mdx murine model of DMD with repeated i.m. injections of PDGF-BB. We observed that regenerating and necrotic muscle fibers in muscle biopsy samples from DMD patients expressed PDGF-BB. In vitro, PDGF-BB attracted myoblasts and activated their proliferation. Analysis of muscles from the animals treated with PDGF-BB showed an increased population of satellite cells and an increase in the number of regenerative fibers, with a reduction in inflammatory infiltrates, compared with those in vehicle-treated mice. Based on our results, PDGF-BB may play a protective role in muscular dystrophies by enhancing muscle regeneration through activation of satellite cell proliferation and migration.

AG1296 enhances plaque stability via inhibiting inflammatory responses and decreasing MMP-2 and MMP-9 expression in ApoE-/- mice

BACKGROUND

Atherosclerosis is a chronic process that progresses to unstable plaques. Plaque rupture leads to deleterious consequences such as acute coronary syndrome, thrombosis and stroke. AG1296 is a potent tyrosine kinase inhibitor which is able to block PDGF-PDGFR signaling pathway. This study aims to assess the effect of AG1296 on plaque stability and explore the potential mechanisms.

METHODS

Atherosclerotic plaques were induced in carotid arteries in ApoE-/- mice by perivascular collar placement. All mice were randomly divided into PBS and AG1296 groups. 3 weeks after the surgery, the carotid arteries were harvested for histological analysis.

RESULTS

In AG1296 group, plaque area decreased by 41.5% (p = 0.0041) and the contents of macrophages and lipids decreased by 43.5% (p = 0.0003) and 35.6% (p = 0.0032) respectively. The contents of smooth muscle cells increased by 22.3% (p = 0.0214) in AG1296 group. Vulnerable index decreased by 48.3% (p = 0.0002). The inflammation factors IL-6 and TNF- alpha decreased by 49.0% (p = 0.0008) and 51.8% (p < 0.0001) and matrix metalloproteinases MMP-2 and MMP-9 decreased by 54.1% (p = 0.0004) and 37.1% (p < 0.0001) in AG1296 group. M1 macrophage markers (MCP-1) were downregulated by 30.3% (p = 0.0007) and M2 macrophage markers (ARG-1) were increased by 55.2% (p = 0.0009) in AG1296 group.

CONCLUSION

AG1296 inhibited the atherosclerotic plaque progression and enhanced plaque stability by inhibiting inflammatory responses, reducing the expression of matrix metalloproteinases and promoting macrophages from proinflammatory phenotype to anti-inflammatory phenotype.

Inhibition of estrogen related receptor α attenuates vascular smooth muscle cell proliferation and migration by regulating RhoA/p27Kip1 and β-Catenin/Wnt4 signaling pathway

RhoA/p27Kip1 and β-Catenin/Wnt4 signaling processes play central roles in proliferation and migration in vascular smooth muscle cells (VSMCs). ERRα, a member of orphan nuclear receptors, is a potent prognostic factor in breast, ovarian, colon and other types of tumors. However, biological significance of ERRα in VSMCs as well as the molecular mechanisms remains largely unknown. Therefore, the present study was designed to investigate whether ERRα is involved in the proliferation and migration of VSMCs in vitro and neointimal formation in vivo. The specific ERRα inverse agonist XCT790 (or ERRα shRNA) resulted in a significant inhibition of proliferation and phenotypic switch in cultured rat aortic SMCs (RASMCs). Furthermore, cycle progression, cell cycle protein transcription as well as hyperphosphorylation of the retinoblastoma protein (Rb) in RASMCs were prevented by downregulation of ERRα. Transwell assay demonstrated that migratory capacity of RASMCs was also inhibited the treatment of XCT790 (or ERRα shRNA). At the molecular levels, RhoA/p27Kip1 and β-Catenin/Wnt4 signaling pathways are involved in ERRα-mediated RASMCs growth and migration. Finally, inhibition of ERRα significantly attenuated neointimal formation in rat artery after balloon injury. These results help to further understand vascular remodeling and suggest that ERRα might be a potential target for the treatment of vascular proliferative diseases.

Genetic, physiological and comparative genomic studies of hypertension and insulin resistance in the spontaneously hypertensive rat

We previously mapped hypertension-related insulin resistance quantitative trait loci (QTLs) to rat chromosomes 4, 12 and 16 using adipocytes from F2 crosses between spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats, and subsequently identified Cd36 as the gene underlying the chromosome 4 locus. The identity of the chromosome 12 and 16 genes remains unknown. To identify whole-body phenotypes associated with the chromosome 12 and 16 linkage regions, we generated and characterised new congenic strains, with WKY donor segments introgressed onto an SHR genetic background, for the chromosome 12 and 16 linkage regions. We found a >50% increase in insulin sensitivity in both the chromosome 12 and 16 strains. Blood pressure and left ventricular mass were reduced in the two congenic strains consistent with the congenic segments harbouring SHR genes for insulin resistance, hypertension and cardiac hypertrophy. Integrated genomic analysis, using physiological and whole-genome sequence data across 42 rat strains, identified variants within the congenic regions in Upk3bl, RGD1565131 and AABR06087018.1 that were associated with blood pressure, cardiac mass and insulin sensitivity. Quantitative trait transcript analysis across 29 recombinant inbred strains showed correlation between expression of Hspb1, Zkscan5 and Pdgfrl with adipocyte volume, systolic blood pressure and cardiac mass, respectively. Comparative genome analysis showed a marked enrichment of orthologues for human GWAS-associated genes for insulin resistance within the syntenic regions of both the chromosome 12 and 16 congenic intervals. Our study defines whole-body phenotypes associated with the SHR chromosome 12 and 16 insulin-resistance QTLs, identifies candidate genes for these SHR QTLs and finds human orthologues of rat genes in these regions that associate with related human traits. Further study of these genes in the congenic strains will lead to robust identification of the underlying genes and cellular mechanisms.

Summary: Comparative genome analyses identify candidate genes for hypertension and insulin resistance on rat chromosomes 12 and 16, and marked enrichment of insulin resistance genes in the syntenic regions of the human genome.

Imatinib attenuates cerebrovascular injury and phenotypic transformation after intracerebral hemorrhage in rats

This study explored the hypothesis that intracerebral hemorrhage (ICH) promotes release of diffusible factors that can significantly influence the structure and function of cerebral arteries remote from the site of injury, through action on platelet-derived growth factor (PDGF) receptors. Four groups of adult male Sprague-Dawley rats were studied (n = 8 each): 1) sham; 2) sham + 60 mg/kg ip imatinib; 3) ICH (collagenase method); and 4) ICH + 60 mg/kg ip imatinib given 60 min after injury. At 24 h after injury, sham artery passive diameters (+3 mM EGTA) averaged 244 ± 7 µm (at 60 mmHg). ICH significantly increased passive diameters up to 6.4% and decreased compliance up to 42.5%. For both pressure- and potassium-induced contractions, ICH decreased calcium mobilization up to 26.2% and increased myofilament calcium sensitivity up to 48.4%. ICH reduced confocal colocalization of smooth muscle α-actin (αActin) with nonmuscle myosin heavy chain (MHC) and increased its colocalization with smooth muscle MHC, suggesting that ICH promoted contractile differentiation. ICH also enhanced colocalization of myosin light chain kinase (MLCK) with both αActin and regulatory 20-kDa myosin light chain. All effects of ICH on passive diameter, compliance, contractility, and contractile protein colocalization were significantly reduced or absent in arteries from animals treated with imatinib. These findings support the hypothesis that ICH promotes release into the cerebrospinal fluid of vasoactive factors that can diffuse to and promote activation of cerebrovascular PDGF receptors, thereby altering the structure, contractile protein organization, contractility, and smooth muscle phenotype of cerebral arteries remote from the site of hemorrhage.