Sustained Vascular Smooth Muscle Research Articles

Dimethyl Fumarate Mediates Sustained Vascular Smooth Muscle Cell Remodeling in a Mouse Model of Cerebral Aneurysm.

Cerebral aneurysms (CA) are a type of vascular disease that causes significant morbidity and mortality with rupture. Dysfunction of the vascular smooth muscle cells (VSMCs) from circle of Willis (CoW) vessels mediates CA formation, as they are the major cell type of the arterial wall and play a role in maintaining vessel integrity. Dimethyl fumarate (DMF), a first-line oral treatment for relapsing-remitting multiple sclerosis, has been shown to inhibit VSMC proliferation and reduce CA formation in a mouse model. Potential unwanted side effects of DMF on VSMC function have not been investigated yet. The present study characterizes the impact of DMF on VSMC using single-cell RNA-sequencing (scRNA-seq) in CoW vessels following CA induction and further explores its role in mitochondrial function using in vitro VSMC cultures. Two weeks of DMF treatment following CA induction impaired the transcription of the glutathione redox system and downregulated mitochondrial respiration genes in VSMCs. In vitro, DMF treatment increased lactate formation and enhanced the mitochondrial production of reactive oxygen species (ROS). These effects rendered VSMCs vulnerable to oxidative stress and led to mitochondrial dysfunction and enhancement of apoptosis. Taken together, our data support the concept that the DMF-mediated antiproliferative effect on VSMCs is linked to disturbed antioxidative functions resulting in altered mitochondrial metabolism. This negative impact of DMF treatment on VSMCs may be linked to preexisting alterations of cerebrovascular function due to renal hypertension. Therefore, before severe adverse effects emerge, it would be clinically relevant to develop indices or biomarkers linked to this disturbed antioxidative function to monitor patients undergoing DMF treatment.

Mechanism of sustained vascular smooth muscle relaxation by nitroglycerin

Mechanism of sustained vascular smooth muscle relaxation by nitroglycerin

Targeting Pim Kinases and DAPK3 to Control Hypertension

Sustained vascular smooth muscle hypercontractility promotes hypertension and cardiovascular disease. The etiology of hypercontractility is not completely understood. New therapeutic targets remain vitally important for drug discovery. Here we report that Pim kinases, in combination with DAPK3, regulate contractility and control hypertension. Using a co-crystal structure of lead molecule (HS38) in complex with DAPK3, a dual Pim/DAPK3 inhibitor (HS56) and selective DAPK3 inhibitors (HS94 and HS148) were developed to provide mechanistic insight into the polypharmacology of hypertension. Invitro and exvivo studies indicated that Pim kinases directly phosphorylate smooth muscle targets and that Pim/DAPK3 inhibition, unlike selective DAPK3 inhibition, significantly reduces contractility. Invivo, HS56 decreased blood pressure in spontaneously hypertensive mice in a dose-dependent manner without affecting heart rate. These findings suggest including Pim kinase inhibition within a multi-target engagement strategy for hypertension management.HS56 represents a significant step in the development of molecularly targeted antihypertensive medications.

In This Issue

HomeCirculation ResearchVol. 108, No. 11In This Issue Free AccessIn BriefPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessIn BriefPDF/EPUBIn This Issue Originally published27 May 2011https://doi.org/10.1161/RES.0b013e318222b9fcCirculation Research. 2011;108:1299Role of Tryptase in Abdominal Aortic Aneurysm (p 1316)Zhang et al reveal tryptase as a mast cell mediator of aortic aneurysm.Download figureDownload PowerPointAbdominal aortic aneurysms (AAAs) that develop because of the expansion of the artery like a balloon can be life-threatening in the event of rupture. The hope is that AAAs can be caught early and surgically repaired. Zhang et al have now found that in patients with AAA, serum tryptase levels correlate with expansion and pose a risk for later surgical repair and mortality. This suggests that tryptase might serve as a useful biomarker for AAA development. The team also showed that high levels of serum tryptase were a result of an increase in mast cells, previously described in AAA patients and in mouse models of AAA. Furthermore, the increased tryptase was not just a reflection of AAA development, it was actually the cause. Mice lacking the gene for tryptase were protected from experimentally induced AAA lesion expansion, the team found. These mice had fewer inflammatory and apoptotic cells at AAA lesions and less elastin degradation. Importantly, methods used to block tryptase activity —such as protease inhibitors—might offer beneficial treatments for AAA patients, say the authors.CCICR and RhoA/ROCK in Vascular Smooth Muscle (p 1348)Fernandez-Tenorio et al discover the wide-ranging cellular effects of a calcium channel in sustained vascular smooth muscle contraction.Download figureDownload PowerPointSustained vascular smooth muscle contraction is associated with pathologies such as hypertension, angina, and cardiac arrhythmias. Although both L-type voltage-gated calcium channels (VGCCs) and contractile machinery sensitization by RhoA/Rho kinase have been implicated in sustained contraction, it is unclear how these elements are mechanistically interrelated. VGCCs both enable the influx of calcium from extracellular pools and control release of calcium from intracellular stores—namely, through the sarcoplasmic reticulum. The latter pathway is controlled via the activation of G protein/phospholipase C and other downstream cell signaling molecules. Fernandez-Tenorio et al showed that this so-called metabotropic pathway also activated the RhoA/Rho-mediated contractile machinery sensitization. These findings indicate that the effect of VGCCs on sustained vascular smooth muscle cell contraction encompasses more downstream pathways than previously thought. The results could be useful for optimizing treatments for hypertension, angina, and arrhythmias, say the team.HOXC9 and Endothelial Quiescence (p 1367)HOXC9 halts vertebrate vascular development, report Stoll et al.Download figureDownload PowerPointTranscription factors of the homeobox (HOX) family are important developmental morphogenes involved in the growth of numerous bodily structures and systems. Their role in vascular development, however, is not well understood. HOXC9 is expressed in blood vessels, which prompted Stoll et al to investigate whether this family member has any role in vascular development. They found that HOXC9 displayed a distinctive pattern of expression in cultured human vascular endothelial cells: sparsely growing cells had little of the factor, but expression increased along with cell density. Apparently, HOXC9 inhibited cell proliferation and the ability of the cells to migrate and form tubes in culture. Further experiments revealed that HOXC9 suppressed the expression of the interleukin (IL)-8 gene—a known angiogenic factor. Indeed, HOXC9's effect on migration and tube formation could be reversed by administering exogenous IL-8. Proliferation remained unaltered, however, suggesting that HOXC9 targets another factor(s) to exert this effect. Using Zebrafish embryos, the team showed that the overexpression of HOXC9, or indeed loss of IL-8, inhibited normal in vivo vascular development. Given that IL-8 can promote angiogenesis in certain tumors, boosting HOXC9 may be a good therapeutic countermeasure.Written by Ruth Williams Previous Back to top Next FiguresReferencesRelatedDetails May 27, 2011Vol 108, Issue 11 Advertisement Article InformationMetrics © 2011 American Heart Association, Inc.https://doi.org/10.1161/RES.0b013e318222b9fc Originally publishedMay 27, 2011 PDF download Advertisement

Metabotropic Regulation of RhoA/Rho-Associated Kinase by L-type Ca 2+ Channels

Background: Sustained vascular smooth muscle contraction is mediated by extracellular Ca 2+ influx through L-type voltage-gated Ca 2+ channels (VGCC) and RhoA/Rho-associated kinase (ROCK)-dependent Ca 2+ sensitization of the contractile machinery. VGCC activation can also trigger an ion-independent metabotropic pathway that involves G-protein/phospholipase C activation, inositol 1,4,5-trisphosphate synthesis, and Ca 2+ release from the sarcoplasmic reticulum (calcium channel-induced Ca 2+ release). We have studied the functional role of calcium channel-induced Ca 2+ release and the inter-relations between Ca 2+ channel and RhoA/ROCK activation. Methods and Results: We have used normal and genetically modified animals to study single myocyte electrophysiology and fluorimetry as well as cytosolic Ca 2+ and diameter in intact arteries. These analyses were complemented with measurement of tension and RhoA activity in normal and reversibly permeabilized arterial rings. We have found that, unexpectedly, L-type Ca 2+ channel activation and subsequent metabotropic Ca 2+ release from sarcoplasmic reticulum participate in depolarization-evoked RhoA/ROCK activity and sustained arterial contraction. We show that these phenomena do not depend on the change in the membrane potential itself, or the mere release of Ca 2+ from the sarcoplasmic reticulum, but they require the simultaneous activation of VGCC and the downstream metabotropic pathway with concomitant Ca 2+ release. During protracted depolarizations, refilling of the stores by a residual extracellular Ca 2+ influx through VGCC helps maintaining RhoA activity and sustained arterial contraction. Conclusions: These findings reveal that calcium channel-induced Ca 2+ release has a major role in tonic vascular smooth muscle contractility because it links membrane depolarization and Ca 2+ channel activation with metabotropic Ca 2+ release and sensitization (RhoA/ROCK stimulation).

Counterpoint: Chronic Hypoxia-induced Pulmonary Hypertension does not Lead to Loss of Pulmonary Vasculature

Exposure of native sea level dwellers to chronic hypoxia due to migration to high altitude leads to the development of increased pulmonary vascular resistance causing pulmonary hypertension. In some susceptible individuals this progressively worsens causing right ventricular failure and ultimately

Mediators of alkalosis-induced relaxation in pulmonary arteries from normoxic and chronically hypoxic piglets.

Alkalosis-induced relaxation was measured in precontracted arterial rings from 1-wk-old piglets exposed to normoxia or to 3 days of chronic hypoxia. In normoxic piglet arteries, alkalosis-induced relaxation was blunted in arteries without functional endothelium and in arteries treated with nitric oxide synthase or guanylate cyclase inhibitors but not in arteries treated with cyclooxygenase inhibitors or Ca2+- and ATP-dependent K+-channel inhibitors. Inhibition of voltage-dependent K+ channels with 10(-3) M 4-aminopyridine also failed to block alkalosis-induced relaxation. 4-Aminopyridine at 10(-2) M did block the response, but this may have been due to sustained vascular smooth muscle depolarization. Arteries from hypoxic piglets exhibited greater contraction to the thromboxane mimetic U-46619, decreased endothelium-dependent relaxation, and blunted alkalosis-induced relaxation. The residual relaxation was eliminated by nitric oxide synthase but not by cyclooxygenase or voltage-dependent K+-channel inhibition. Alkalosis-induced relaxation of newborn piglet pulmonary arteries appears to be mediated by the nitric oxide-cGMP pathway and is attenuated after 3 days of hypoxia, likely because of decreased nitric oxide activity.

Protein Kinase C Activation during Ca2+-Independent Vascular Smooth Muscle Contraction

The cellular signaling mechanisms that modulate the sustained vascular smooth muscle contractions that occur in vasospasm are not known. We and others have hypothesized that a kinase cascade involving protein kinase C (PKC) modulates sustained vascular smooth muscle contraction. The purpose of this investigation was to develop a model in which the traditional contractile pathways involving myosin light chain phosphorylation are not activated and determine if the PKC pathway is activated under these conditions. The phosphorylation of caldesmon, myosin light chain (MLC20), and the specific PKC substrate, MARCKS (myristoylated, alanine-rich C-kinase substrate) was measured in bovine carotid arterial smoothmuscle (BCASM) stimulated with phorbol 12,13-dibutyrate (PDBu) under Ca2+-containing and Ca2+-free conditions. PDBu stimulation led to increases in caldesmon and MARCKS phosphorylation to the same degree in the presence or absence of Ca2+. PDBu stimulation but did not lead to increases in MLC20phosphorylation over basal levels in Ca2+-free conditions. Immunoblot analysis of BCASM using PKC isoform-specific antibodies demonstrated the presence of one “Ca2+- dependent” PKC isoform: alpha, and two of the “Ca2+-independent” isoforms: epsilon and zeta. These data suggest that Ca2+-independent isoforms of PKC may play a role in the sustained phase of BCASM contractions through a kinase cascade that involves caldesmon and MARCKS phosphorylation but not MLC20phosphorylation.

A030 Angiotensin II-activated map kinase pathways are associated with sustained vascular smooth muscle contraction

A030 Angiotensin II-activated map kinase pathways are associated with sustained vascular smooth muscle contraction

Thrombin-induced vasospasm: Cellular signaling mechanisms

Background: In the setting of arterial injury, thrombin contributes to the hemostatic process by activating the coagulation cascade and platelets. We hypothesized that thrombin also contributes to hemostasis by inducing vasospasm. The purpose of this investigation was to characterize the cellular signaling mechanisms that modulate thrombin-induced vascular smooth muscle contractions. Methods: Contractile responses of intact bovine carotid artery smooth muscles were determined in a muscle bath. Contractile responses were correlated with phosphorylation events as determined with whole cell phosphorylation and two-dimensional gel electrophoresis and with immunoblotting of glycerol-urea or two-dimensional gels. Results: Thrombin (1 to 1000 units/ml) induced sustained vascular smooth muscle contractions of similar magnitude as the potent contractile agonist, endothelin. Thrombin-induced contractions were associated with increases in the phosphorylation of the myosin light chains (MLC 20) and in the tyrosine phosphorylation of mitogen-activated protein kinase. Conclusions: These data suggest that thrombin is a potent physiologic contractile agonist that may modulate some forms of vasospasm. Thrombin-induced contractions are associated with the activation of two cellular signaling pathways, the myosin light chain kinase and the mitogen-activated protein kinase pathways. (Surgery 1998;123:46-50.)

Thrombin-induced vasospasm: Cellular signaling mechanisms

Background: In the setting of arterial injury, thrombin contributes to the hemostatic process by activating the coagulation cascade and platelets. We hypothesized that thrombin also contributes to hemostasis by inducing vasospasm. The purpose of this investigation was to characterize the cellular signaling mechanisms that modulate thrombin-induced vascular smooth muscle contractions. Methods: Contractile responses of intact bovine carotid artery smooth muscles were determined in a muscle bath. Contractile responses were correlated with phosphorylation events as determined with whole cell phosphorylation and two-dimensional gel electrophoresis and with immunoblotting of glycerol-urea or two-dimensional gels. Results: Thrombin (1 to 1000 units/ml) induced sustained vascular smooth muscle contractions of similar magnitude as the potent contractile agonist, endothelin. Thrombin-induced contractions were associated with increases in the phosphorylation of the myosin light chains (MLC20) and in the tyrosine phosphorylation of mitogen-activated protein kinase. Conclusions: These data suggest that thrombin is a potent physiologic contractile agonist that may modulate some forms of vasospasm. Thrombin-induced contractions are associated with the activation of two cellular signaling pathways, the myosin light chain kinase and the mitogen-activated protein kinase pathways. (Surgery 1998;123:46-50.)

Mitogen-activated protein kinase activation: an alternate signaling pathway for sustained vascular smooth muscle contraction.

The vascular smooth muscle determines the dynamic caliber of the blood vessel and hence is the final effector cell in modulating vasomotor tone. Although considerable information is available regarding the physiologic agonists that induce contraction, less is known about the cellular signaling events that lead to long-lasting contractions or vasospasm. We examined the hypothesis that activation of mitogen-activated protein (MAP) kinase may be associated with sustained smooth muscle contractions. Physiologic contractile responses were determined in intact bovine carotid artery smooth muscles in a muscle bath. Corresponding signaling events were determined with immunoblots using antiphosphotyrosine antibodies or immunoprecipitation of whole-cell phosphorylated strips of muscle. The tyrosine kinase inhibitor, genestein, significantly inhibited the magnitude of contractions induced by phorbol ester, endothelin, angiotensin, and serotonin. In addition, genestein inhibited the sustained phase of contractions induced by serotonin. Serotonin-induced vascular smooth muscle contractions were temporally associated with an increase in the phosphorylation of MAP kinase. These data suggest that the activation of MAP kinase is associated with sustained vascular smooth muscle contractions. Pharmacologic manipulation of MAP kinase activation may lead to new approaches to treat pathologic circumstances of increased vasomotor tone such as vasospasm.

Kinase activation and smooth muscle contraction in the presence and absence of calcium

The intracellular signalling mechanisms that modulate the sustained vascular smooth muscle contractions that occur with vasospasm are not well understood. The purpose of this investigation was to examine cell signalling mechanisms that account for sustained vascular smooth muscle contraction, independent of increases in intracellular Ca2+ concentrations ([Ca2+]i). Fresh bovine carotid artery smooth muscles contractile responses were examined in a muscle bath. [Ca2+]i was depleted by use of the extracellular Ca2+ chelator, ethylene glycol-bis(beta-aminoethylether) N,N,N',N'-tetraacetic acid and the intracellular chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N',-tetraacetic acid. In Ca(2+)-free conditions, depolarizing the membrane with high extracellular KCI failed to elicit a contraction. In addition, in Ca(2+)-free conditions the ([Ca2+]i) was less than 10 nmol/L as determined with the Ca(2+)-indicator, Fura 2. The protein kinase C (PKC) activator, phorbol 12, 13-dibutyrate (PDBu), induced slowly developing sustained contractions in bovine carotid artery smooth muscle, and the magnitude of the contractile response to PDBu (10 nmol/L to 10 mumol/L) was the same in the presence and absence of Ca2+. PDBu induced contractions in Ca(2+)-free conditions were not inhibited by the myosin light chain kinase inhibitor, ML-9 (50 mumol/L), but were inhibited by the PKC inhibitor, staurosporine (50 nmol/L). These data suggest that vascular smooth muscle contractions can occur under conditions where the [Ca2+]i is low and fixed and that these contractions may be mediated by PKC.

Cellular action and interactions of arginine vasopressin in vascular smooth muscle: mechanisms and clinical implications.

In recent years, much has been learned about the vascular action of arginine vasopressin (AVP) including (1) the structure, internalization, and recycling of the V1 AVP receptor; (2) the AVP postreceptor signaling events for the initial and sustained vascular smooth muscle cell contraction as well as the hormone's mitogenic effect; (3) the process of homologous and heterologous AVP desensitization in vascular smooth muscle cells; (4) the interaction of AVP with other vasoconstrictor and vasodilator hormones; (5) the vascular interaction of AVP with endothelial events; and (6) the vascular interactions that may occur with systemic acidemia or alkalemia as well as with ethanol. The various potential clinical and biochemical implications of these results are discussed briefly.