α1C S1928 Phosphorylation of CaV1.2 Channel Controls Vascular Reactivity and Blood Pressure.

BACKGROUND: Increased vascular CaV1.2 channel function causes enhanced arterial tone during hypertension. This is mediated by elevations in angiotensin II/protein kinase C signaling. Yet, the mechanisms underlying these changes are unclear. We hypothesize that α1C phosphorylation at serine 1928 (S1928) is a key event mediating increased CaV1.2 channel function and vascular reactivity during angiotensin II signaling and hypertension. METHODS AND RESULTS: The hypothesis was examined in freshly isolated mesenteric arteries and arterial myocytes from control and angiotensin II-infused mice. Specific techniques include superresolution imaging, proximity ligation assay, patch-clamp electrophysiology, Ca2+ imaging, pressure myography, laser speckle imaging, and blood pressure telemetry. Hierarchical "nested" and appropriate parametric or nonparametric t test and ANOVAs were used to assess statistical differences. We found that angiotensin II redistributed the CaV1.2 pore-forming α1C subunit into larger clusters. This was correlated with elevated CaV1.2 channel activity and cooperativity, global intracellular Ca2+ and contraction of arterial myocytes, enhanced myogenic tone, and altered blood flow in wild-type mice. These angiotensin II-induced changes were prevented/ameliorated in cells/arteries from S1928 mutated to alanine knockin mice, which contain a negative modulation of the α1C S1928 phosphorylation site. In angiotensin II-induced hypertension, increased α1C clustering, CaV1.2 activity and cooperativity, myogenic tone, and blood pressure in wild-type cells/tissue/mice were averted/reduced in S1928 mutated to alanine samples. CONCLUSIONS: Results suggest an essential role for α1C S1928 phosphorylation in regulating channel distribution, activity and gating modality, and vascular function during angiotensin II signaling and hypertension. Phosphorylation of this single vascular α1C amino acid could be a risk factor for hypertension that may be targeted for therapeutic intervention.

Quercetin regulates pulmonary vascular remodeling in pulmonary hypertension by downregulating TGF-ß1-Smad2/3 pathway.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a worldwide challenging disease characterized by progressive elevation of pulmonary artery pressure. The proliferation, migration and phenotypic transformation of pulmonary smooth muscle cells are the key steps of pulmonary vascular remodeling. Quercetin (3,3', 4', 5, 6-pentahydroxyflavone, Que) is a natural flavonol compound that has antioxidant, anti-inflammatory, anti-tumor and other biological activities. Studies have shown that Que has therapeutic effects on PAH. However, the effect of quercetin on pulmonary vascular remodeling in PAH and its mechanism remain unclear. METHODS AND RESULTS: In vivo, PAH rats were constructed by intraperitoneal injection of monocrotaline (MCT) at 60 mg/kg. Human pulmonary artery smooth muscle cells (HPASMCs) were treated with platelet-derived growth factor BB (PDGF-BB) 20 ng/mL to construct PAH cell model in vitro. The results showed that in vivo studies, MCT could induce right ventricular wall hyperplasia, narrow the small and medium pulmonary artery cavity, up-regulate the expression of proliferating and migration-related proteins proliferating cell nuclear antigen (PCNA) and osteopontin (OPN), and down-regulate the expression of alpha-smooth muscle actin (α-SMA). Que reversed the MCT-induced results. This process works by down-regulating the transforming growth factor-ß1 (TGF-ß1)/ Smad2/3 signaling pathway. In vitro studies, Que had the same effect on PDGF-BB-induced proliferation and migration cell models. CONCLUSIONS: Que inhibits the proliferation, migration and phenotypic transformation of HPASMCs by down-regulating TGF-ß1/Smad2/Smad3 pathway, thereby reducing right ventricular hyperplasia (RVH) and pulmonary vascular remodeling, providing potential pharmacological and molecular explanations for the treatment of PAH.

Effects of high-frequency mechanical stimuli on flow related vascular cell biology.

Mechanical forces related to blood pressure and flow patterns play a crucial role in vascular homeostasis. Perturbations in vascular stresses and strain resulting from changes in hemodynamic may occur in pathological conditions, leading to vascular dysfunction as well as in vascular prosthesis, arteriovenous shunt for hemodialysis and in mechanical circulation support. Turbulent-like blood flows can induce high-frequency vibrations of the vessel wall, and this stimulus has recently gained attention as potential contributors to vascular pathologies, such as development of intimal hyperplasia in arteriovenous fistula for hemodialysis. However, the biological response of vascular cells to this stimulus remains incompletely understood. This review provides an analysis of the existing literature concerning the impact of high-frequency stimuli on vascular cell morphology, function, and gene expression. Morphological and functional investigations reveal that vascular cells stimulated at frequencies higher than the normal heart rate exhibit alterations in cell shape, alignment, and proliferation, potentially leading to vessel remodeling. Furthermore, vibrations modulate endothelial and smooth muscle cells gene expression, affecting pathways related to inflammation, oxidative stress, and muscle hypertrophy. Understanding the effects of high-frequency vibrations on vascular cells is essential for unraveling the mechanisms underlying vascular diseases and identifying potential therapeutic targets. Nevertheless, there are still gaps in our understanding of the molecular pathways governing these cellular responses. Further research is necessary to elucidate these mechanisms and their therapeutic implications for vascular diseases.

Sex differences and role of lysyl oxidase-like 2 in angiotensin II-induced hypertension in mice.

Hypertension, a disease with known sexual dimorphism, accelerates aging-associated arterial stiffening, partly because of the activation of matrix remodeling caused by increased biomechanical load. In this study, we tested the effect of biological sex and the role of the matrix remodeling enzyme lysyl oxidase-like 2 (LOXL2) in hypertension-induced arterial stiffening. Hypertension was induced by angiotensin II (ANG II) infusion via osmotic minipumps in 12- to 14-wk-old male and female mice. Blood pressure and pulse wave velocity (PWV) were measured noninvasively. Wire myography and uniaxial tensile testing were used to test aortic vasoreactivity and mechanical properties. Aortic wall composition was examined by histology and Western blotting. Uniaxial stretch of cultured cells was used to evaluate the effect of biomechanical strain. LOXL2's catalytic function was examined using knockout and inhibition. ANG II infusion-induced hypertension in both genotypes and sexes. Wild-type (WT) males exhibited arterial stiffening in vivo and ex vivo. Aortic remodeling with increased wall thickness, intralamellar distance, higher LOXL2, and collagen I and IV content was noted in WT males. Female mice did not exhibit increased PWV despite the onset of hypertension. LOXL2 depletion improved vascular reactivity and mechanics in hypertensive males. LOXL2 depletion improved aortic mechanics but worsened hypercontractility in females. Hypertensive cyclic strain contributed to LOXL2 upregulation in the cell-derived matrix in vascular smooth muscle cells (VSMCs) but not endothelial cells. LOXL2's catalytic function facilitated VSMC alignment in response to biomechanical strain. In conclusion, in males, arterial stiffening in hypertension is driven both by VSMC response and matrix remodeling. Females are protected from PWV elevation in hypertension. LOXL2 depletion is protective in males with improved mechanical and functional aortic properties. VSMCs are the primary source of LOXL2 in the aorta, and hypertension increases LOXL2 processing and shifts to collagen I accumulation. Overall, LOXL2 depletion offers protection in young hypertensive males and females.NEW & NOTEWORTHY We examined the effect of sex on the evolution of angiotensin II (ANG II)-induced hypertension and the role of lysyl oxidase-like 2 (LOXL2), an enzyme that catalyzes matrix cross linking. While ANG II led to hypertension and worsening vascular reactivity in both sexes, aortic remodeling and stiffening occurred only in males. LOXL2 depletion improved outcomes in males but not females. Thus males and females exhibit a distinct etiology of hypertension and LOXL2 is an effective target in males.

Upregulation of Angiomotin-Like 2 Ameliorates Experimental Pulmonary Arterial Hypertension by Inactivating YAP1 Signaling.

ABSTRACT: Angiomotin-like 2 (AMOTL2) is related to numerous physiological and pathological conditions by affecting signal transduction. However, whether AMOTL2 is linked to pulmonary arterial hypertension (PAH) has not been addressed. This work aimed to investigate the potential role of AMOTL2 in PAH. A decrease in AMOTL2 abundance was observed in the lungs of PAH rats. The upregulation of AMOTL2 significantly decreased right ventricle systolic pressure and right ventricular hypertrophy in PAH rats. Overexpression of AMOTL2 also led to a noteworthy decrease in vascular wall thickness, pulmonary artery area, and collagen deposition in rats with PAH. AMOTL2 was downregulated in hypoxia-stimulated pulmonary arterial smooth muscle cells (PASMCs). Moreover, AMOTL2 overexpression impeded hypoxia-evoked proliferation, migration, and phenotypic transformation in rat PASMCs. Mechanistic investigation revealed that Yes-associated protein 1 (YAP1) activation in PAH rats or hypoxia-stimulated PASMCs was markedly inhibited by AMOTL2 overexpression, which was associated with increased large tumor suppressor 1/2 phosphorylation. The inhibition of large tumor suppressor 1/2 reversed the AMOTL2-mediated inactivation of YAP1. Restoring the activity of YAP1 reversed the inhibitory effect of AMOTL2 on hypoxia-evoked proliferation, migration, and phenotypic transformation of PASMCs. Collectively, these results suggest that AMOTL2 can ameliorate PAH in a rat model by interfering with pulmonary arterial remodeling via the inactivation of YAP1 signaling. Our work indicates that AMOTL2 may be a candidate target for novel drug development for the treatment of PAH.

Ion Channels Remodeling in the Regulation of Vascular Hyporesponsiveness During Shock.

Shock is characterized with vascular hyporesponsiveness to vasoconstrictors, thereby to cause refractory hypotension, insufficient tissue perfusion, and multiple organ dysfunction. The vascular hyporeactivity persisted even though norepinephrine and fluid resuscitation were administrated, it is of critical importance to find new potential target. Ion channels are crucial in the regulation of cell membrane potential and affect vasoconstriction and vasodilation. It has been demonstrated that many types of ion channels including K+ channels, Ca2+ permeable channels, and Na+ channels exist in vascular smooth muscle cells and endothelial cells, contributing to the regulation of vascular homeostasis and vasomotor function. An increasing number of studies suggested that the structural and functional alterations of ion channels located in arteries contribute to vascular hyporesponsiveness during shock, but the underlying mechanisms remained to be fully clarified. Therefore, the expression and functional changes in ion channels in arteries associated with shock are reviewed, to pave the way for further exploring the potential of ion channel-targeted compounds in treating refractory hypotension in shock.

Arterial Smooth Muscle Cell AKAP150 Mediates Exercise-Induced Repression of CaV1.2 Channel Function in Cerebral Arteries of Hypertensive Rats.

BACKGROUND: Hypertension is a major, prevalent risk factor for the development and progression of cerebrovascular disease. Regular exercise has been recommended as an excellent choice for the large population of individuals with mild-to-moderate elevations in blood pressure, but the mechanisms that underlie its vascular-protective and antihypertensive effects remain unknown. Here, we describe a mechanism by which myocyte AKAP150 (A-kinase anchoring protein 150) inhibition induced by exercise training alleviates voltage-dependent L-type Ca2+ channel (CaV1.2) activity and restores cerebral arterial function in hypertension. METHODS: Spontaneously hypertensive rats and newly generated smooth muscle-specific AKAP150 knockin mice were used to assess the role of myocyte AKAP150/CaV1.2 channel in regulating cerebral artery function after exercise intervention. RESULTS: Activation of the AKAP150/PKCα (protein kinase Cα) signaling increased CaV1.2 activity and Ca2+ influx of cerebral arterial myocyte, thus enhancing vascular tone in spontaneously hypertensive rats. Smooth muscle-specific AKAP150 knockin mice were hypertensive with higher CaV1.2 channel activity and increased vascular tone. Furthermore, treatment of Ang II (angiotensin II) resulted in a more pronounced increase in blood pressure in smooth muscle-specific AKAP150 knockin mice. Exercise training significantly reduced arterial myocyte AKAP150 expression and alleviated CaV1.2 channel activity, thus restoring cerebral arterial function in spontaneously hypertensive rats and smooth muscle-specific AKAP150 knockin mice. AT1R (AT1 receptor) and AKAP150 were interacted closely in arterial myocytes. Exercise decreased the circulating Ang II and Ang II-involved AT1R-AKAP150 association in myocytes of hypertension. CONCLUSIONS: The current study demonstrates that aerobic exercise ameliorates CaV1.2 channel function via inhibiting myocyte AKAP150, which contributes to reduced cerebral arterial tone in hypertension.

HMGB2 Release Promotes Pulmonary Hypertension and Predicts Severity and Mortality of Patients With Pulmonary Arterial Hypertension.

BACKGROUND: Pulmonary hypertension (PH) is a progressive and life-threatening disease characterized by pulmonary vascular remodeling, which involves aberrant proliferation and apoptosis resistance of the pulmonary arterial smooth muscle cells (PASMCs), resembling the hallmark characteristics of cancer. In cancer, the HMGB2 (high-mobility group box 2) protein promotes the pro-proliferative/antiapoptotic phenotype. However, the function of HMGB2 in PH remains uninvestigated. METHODS: Smooth muscle cell (SMC)-specific HMGB2 knockout or HMGB2-OE (HMGB2 overexpression) mice and HMGB2 silenced rats were used to establish hypoxia+Su5416 (HySu)-induced PH mouse and monocrotaline-induced PH rat models, respectively. The effects of HMGB2 and its underlying mechanisms were subsequently elucidated using RNA-sequencing and cellular and molecular biology analyses. Serum HMGB2 levels were measured in the controls and patients with pulmonary arterial (PA) hypertension. RESULTS: HMGB2 expression was markedly increased in the PAs of patients with PA hypertension and PH rodent models and was predominantly localized in PASMCs. SMC-specific HMGB2 deficiency or silencing attenuated PH development and pulmonary vascular remodeling in hypoxia+Su5416-induced mice and monocrotaline-treated rats. SMC-specific HMGB2 overexpression aggravated hypoxia+Su5416-induced PH. HMGB2 knockdown inhibited PASMC proliferation in vitro in response to PDGF-BB (platelet-derived growth factor-BB). In contrast, HMGB2 protein stimulation caused the hyperproliferation of PASMCs. In addition, HMGB2 promoted PASMC proliferation and the development of PH by RAGE (receptor for advanced glycation end products)/FAK (focal adhesion kinase)-mediated Hippo/YAP (yes-associated protein) signaling suppression. Serum HMGB2 levels were significantly increased in patients with PA hypertension, and they correlated with disease severity, predicting worse survival. CONCLUSIONS: Our findings indicate that targeting HMGB2 might be a novel therapeutic strategy for treating PH. Serum HMGB2 levels could serve as a novel biomarker for diagnosing PA hypertension and determining its prognosis.

Comparative analysis of antiproliferative and vasodilator effects of drugs for pulmonary hypertension: Extensive in vitro study in rats and human.

An effective pulmonary hypertension (PH) treatment should combine antiproliferative and vasodilator effects. We characterized a wide-range of drugs comparing their anti-proliferative vs vasodilator effects in human and rat pulmonary artery smooth muscle cells (PASMC). Key findings: 1) Approved PH drugs (PDE5 inhibitors, sGC stimulators and PGI2 agonists) are preferential vasodilators. 2) cGMP stimulators were more effective in cells derived from hypertensive rats. 3) Nifedipine acted equally as vasodilator and antiproliferative. 4) quercetin and imatinib were potent dual vasodilator/antiproliferative drugs. 5) Tacrolimus and levosimendan lacked antiproliferative effects. 6) Forskolin, pinacidil and hydroxyfasudil were more effective as antiproliferative in human cells.

Sex-specific cardiovascular remodeling leads to a divergent sex-dependent development of heart failure in aged hypertensive rats.

INTRODUCTION: The prevalence of heart failure with preserved ejection fraction (HFpEF) is continuously rising and predominantly affects older women often hypertensive and/or obese or diabetic. Indeed, there is evidence on sex differences in the development of HF. Hence, we studied cardiovascular performance dependent on sex and age as well as pathomechanisms on a cellular and molecular level. METHODS: We studied 15-week- and 1-year-old female and male hypertensive transgenic rats carrying the mouse Ren-2 renin gene (TG) and compared them to wild-type (WT) controls at the same age. We tracked blood pressure and cardiac function via echocardiography. After sacrificing the 1-year survivors we studied vascular smooth muscle and endothelial function. Isolated single skinned cardiomyocytes were used to determine passive stiffness and Ca2+-dependent force. In addition, Western blots were applied to analyse the phosphorylation status of sarcomeric regulatory proteins, titin and of protein kinases AMPK, PKG, CaMKII as well as their expression. Protein kinase activity assays were used to measure activities of CaMKII, PKG and angiotensin-converting enzyme (ACE). RESULTS: TG male rats showed significantly higher mortality at 1 year than females or WT male rats. Left ventricular (LV) ejection fraction was specifically reduced in male, but not in female TG rats, while LV diastolic dysfunction was evident in both TG sexes, but LV hypertrophy, increased LV ACE activity, and reduced AMPK activity as evident from AMPK hypophosphorylation were specific to male rats. Sex differences were also observed in vascular and cardiomyocyte function showing different response to acetylcholine and Ca2+-sensitivity of force production, respectively cardiomyocyte functional changes were associated with altered phosphorylation states of cardiac myosin binding protein C and cardiac troponin I phosphorylation in TG males only. Cardiomyocyte passive stiffness was increased in TG animals. On a molecular level titin phosphorylation pattern was altered, though alterations were sex-specific. Thus, also the reduction of PKG expression and activity was more pronounced in TG females. However, cardiomyocyte passive stiffness was restored by PKG and CaMKII treatments in both TG sexes. CONCLUSION: Here we demonstrated divergent sex-specific cardiovascular adaptation to the over-activation of the renin-angiotensin system in the rat. Higher mortality of male TG rats in contrast to female TG rats was observed as well as reduced LV systolic function, whereas females mainly developed HFpEF. Though both sexes developed increased myocardial stiffness to which an impaired titin function contributes to a sex-specific molecular mechanism. The functional derangements of titin are due to a sex-specific divergent regulation of PKG and CaMKII systems.

SDF-1/CXCR4 axis participants in the pathophysiology of adult patients with moyamoya disease.

BACKGROUND: Moyamoya disease (MMD) is characterized by an abundance of moyamoya vessels; however, the precise mechanism driving the spontaneous angiogenesis of these compensatory vessels remains unclear. Previous research has established a link between the stromal cell-derived factor-1 (SDF-1)/ CXC receptor 4 (CXCR4) axis and angiogenesis under hypoxic conditions. Nevertheless, the alterations in this axis within the cerebrospinal fluid, arachnoid membranes and vascular tissue of MMD patients have not been fully investigated. METHODS: Our study enrolled 66 adult MMD patients and 61 patients with atherosclerotic vascular disease (ACVD). We investigated the SDF-1 concentration in cerebrospinal fluid (CSF) and CXCR4 expression level on the arachnoid membranes and vascular tissue. We utilized enzyme-linked immunosorbent assay and immunohistochemistr. Additionally, we cultured and stimulated human brain microvascular endothelial cells (HBMECs) and smooth muscle cells (SMCs) under oxygen and glucose deprivation (OGD) conditions followed by reoxygenation, to examine any changes in the SDF-1/CXCR4 axis. RESULTS: The results demonstrated an elevation in the level of SDF-1 in CSF among MMD patients compared to those with ACVD. Moreover, the expression of CXCR4 in arachnoid membranes and vascular tissue showed a similar trend. Furthermore, the content of CXCR4 in HBMECs and SMCs increased with the duration of ischemia and hypoxia. However, it was observed that the expression of CXCR4 decreased at OGD/R 24h compared to OGD 24h. The temporal pattern of SDF-1 expression in HBMECs and SMCs mirrored that of CXCR4 expression. CONCLUSION: These findings indicate a critical role for the SDF-1/CXCR4 axis in the angiogenesis of moyamoya disease.

Changes in arterial myocyte excitability induced by subarachnoid hemorrhage in a rat model.

Aneurismal subarachnoid hemorrhage (aSAH) is a neurovascular disease produced by the rupture of the cerebral arteries and the extravasation of blood to the subarachnoid space and is accompanied by severe comorbidities. Secondarily associated vasospasm is one of the main side effects after hydrocephalus and possible rebleeding. Here, we analyze the alterations in function in the arteries of a rat model of SAH. For this, autologous blood was injected into the cisterna magna. We performed electrophysiological, microfluorimetric, and molecular biology experiments at different times after SAH to determine the functional and molecular changes induced by the hemorrhage. Our results confirmed that in SAH animals, arterial myocytes were depolarized on days 5 and 7, had higher [Ca2+]i on baseline, peaks and plateaus, and were more excitable at low levels of depolarization on day 7, than in the control and sham animals. Microarray analysis showed that, on day 7, the sets of genes related to voltage-dependent Ca2+ channels and K+ dynamics in SAH animals decreased, while the voltage-independent Ca2+ dynamics genes were over-represented. In conclusion, after SAH, several mechanisms involved in arterial reactivity were altered in our animal model, suggesting that there is no unique cause of vasospasm and alterations in several signaling pathways are involved in its development.

Hypusine Signaling Promotes Pulmonary Vascular Remodeling in Pulmonary Arterial Hypertension.

Rationale: The ubiquitous polyamine spermidine is essential for cell survival and proliferation. One important function of spermidine is to serve as a substrate for hypusination, a posttranslational modification process that occurs exclusively on eukaryotic translation factor 5A (eIF5A) and ensures efficient translation of various gene products. Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by progressive obliteration of the small pulmonary arteries (PAs) caused by excessive proliferation of PA smooth muscle cells (PASMCs) and suppressed apoptosis. Objectives: To characterize the role of hypusine signaling in PAH. Methods: Molecular, genetic, and pharmacological approaches were used both in vitro and in vivo to investigate the role of hypusine signaling in pulmonary vascular remodeling. Measurements and Main Results: Hypusine forming enzymes-deoxyhypusine synthase (DHPS) and deoxyhypusine hydroxylase (DOHH)-and hypusinated eukaryotic translation factor 5A are overexpressed in distal PAs and isolated PASMCs from PAH patients and animal models. In vitro, inhibition of DHPS using N1-guanyl-1,7-diaminoheptane or shRNA resulted in a decrease in PAH-PASMC resistance to apoptosis and proliferation. In vivo, inactivation of one allele of Dhps targeted to smooth muscle cells alleviates PAH in mice, and its pharmacological inhibition significantly decreases pulmonary vascular remodeling and improves hemodynamics and cardiac function in two rat models of established PAH. With mass spectrometry, hypusine signaling is shown to promote the expression of a broad array of proteins involved in oxidative phosphorylation, thus supporting the bioenergetic requirements of cell survival and proliferation. Conclusions: These findings support inhibiting hypusine signaling as a potential treatment for PAH.

Long-term simulated microgravity fosters carotid aging-like changes via Piezo1.

AIMS: Elucidating the impacts of long-term spaceflight on cardiovascular health is urgently needed in face of the rapid development of human space exploration. Recent reports including the NASA Twins Study on vascular deconditioning and aging of astronauts in spaceflight are controversial. The aims of this study were to elucidate whether long-term microgravity promotes vascular aging and the underlying mechanisms. METHODS AND RESULTS: Hindlimb unloading (HU) by tail suspension was used to simulate microgravity in rats and mice. The dynamic changes of carotid stiffness in rats during 8 weeks of HU were determined. Simulated microgravity led to carotid artery aging-like changes as evidenced by increased stiffness, thickness, fibrosis, and elevated senescence biomarkers in the HU rats. Specific deletion of the mechanotransducer Piezo1 in vascular smooth muscles significantly blunted these aging-like changes in mice. Mechanistically, mechanical stretch-induced activation of Piezo1 elevated microRNA-582-5p in vascular smooth muscle cells, with resultant enhanced synthetic cell phenotype and increased collagen deposition via PTEN/PI3K/Akt signalling. Importantly, inhibition of miRNA-582-5p alleviated carotid fibrosis and stiffness not only in HU rats but also in aged rats. CONCLUSIONS: Long-term simulated microgravity induces carotid aging-like changes via the mechanotransducer Piezo1-initiated and miRNA-mediated mechanism.

IP3 receptor orchestrates maladaptive vascular responses in heart failure.

Patients with heart failure (HF) have augmented vascular tone, which increases cardiac workload, impairing ventricular output and promoting further myocardial dysfunction. The molecular mechanisms underlying the maladaptive vascular responses observed in HF are not fully understood. Vascular smooth muscle cells (VSMCs) control vasoconstriction via a Ca2+-dependent process, in which the type 1 inositol 1,4,5-trisphosphate receptor (IP3R1) on the sarcoplasmic reticulum (SR) plays a major role. To dissect the mechanistic contribution of intracellular Ca2+ release to the increased vascular tone observed in HF, we analyzed the remodeling of IP3R1 in aortic tissues from patients with HF and from controls. VSMC IP3R1 channels from patients with HF and HF mice were hyperphosphorylated by both serine and tyrosine kinases. VSMCs isolated from IP3R1VSMC-/- mice exhibited blunted Ca2+ responses to angiotensin II (ATII) and norepinephrine compared with control VSMCs. IP3R1VSMC-/- mice displayed significantly reduced responses to ATII, both in vivo and ex vivo. HF IP3R1VSMC-/- mice developed significantly less afterload compared with HF IP3R1fl/fl mice and exhibited significantly attenuated progression toward decompensated HF and reduced interstitial fibrosis. Ca2+-dependent phosphorylation of the MLC by MLCK activated VSMC contraction. MLC phosphorylation was markedly increased in VSMCs from patients with HF and HF mice but reduced in VSMCs from HF IP3R1VSMC-/- mice and HF WT mice treated with ML-7. Taken together, our data indicate that VSMC IP3R1 is a major effector of increased vascular tone, which contributes to increased cardiac afterload and decompensation in HF.

Endothelial-derived extracellular microRNA-92a promotes arterial stiffness by regulating phenotype changes of vascular smooth muscle cells.

Endothelial dysfunction and vascular smooth muscle cell (VSMC) plasticity are critically involved in the pathogenesis of hypertension and arterial stiffness. MicroRNAs can mediate the cellular communication between vascular endothelial cells (ECs) and neighboring cells. Here, we investigated the role of endothelial-derived extracellular microRNA-92a (miR-92a) in promoting arterial stiffness by regulating EC-VSMC communication. Serum miR-92a level was higher in hypertensive patients than controls. Circulating miR-92a level was positively correlated with pulse wave velocity (PWV), systolic blood pressure (SBP), diastolic blood pressure (DBP), and serum endothelin-1 (ET-1) level, but inversely with serum nitric oxide (NO) level. In vitro, angiotensin II (Ang II)-increased miR-92a level in ECs mediated a contractile-to-synthetic phenotype change of co-cultured VSMCs. In Ang II-infused mice, locked nucleic acid-modified antisense miR-92a (LNA-miR-92a) ameliorated PWV, SBP, DBP, and impaired vasodilation induced by Ang II. LNA-miR-92a administration also reversed the increased levels of proliferative genes and decreased levels of contractile genes induced by Ang II in mouse aortas. Circulating serum miR-92a level and PWV were correlated in these mice. These findings indicate that EC miR-92a may be transported to VSMCs via extracellular vesicles to regulate phenotype changes of VSMCs, leading to arterial stiffness.

Dysregulation of interaction between LOXhigh fibroblast and smooth muscle cells contributes to the pathogenesis of aortic dissection.

Rationale: While cell-cell interaction plays a critical role in physiology and disease, a comprehensive understanding of its dynamics in vascular homeostasis and diseases is yet absent. Methods: Here, by use of single-cell RNA-sequencing and multi-color staining, we delineate the cellular composition and spatial characterization of human aorta with or without aortic dissection (AD). Results: Scrutinization of cell subtype alterations revealed significantly changed fibroblast (FB)-smooth muscle cell (SMC) interactions in AD. Of these cellular interactions, LOXhigh fibroblast (fibroblast subtype 2, FB2) in diseased state exerted the most pronounced effects on pathological deterioration of SMCs in AD. In addition, pharmacologically targeting the BMP (bone morphogenetic protein) signaling pathway effectively suppressed FB2 state transition and reduced AD incidence in mice. Finally, COL5A1 (collagen type V alpha 1 chain), one of the secreted proteins released from FB2, was significantly higher in the plasma of AD patients than in control patients, suggesting its potential use as a biomarker for AD diagnosis. Conclusions: Our work not only identified a pivotal role of a specific FB subtype in AD progression, but also shed light on cell interaction dynamics in vascular diseases.