β-Asarone-induced vasorelaxation in isolated rat mesenteric artery: An efficacy vs toxicity paradox of Acorus calamus.

See related article, pages 1483–1491 The Notch family of receptors, Notch1 to -4, are heterodimer transmembrane proteins, consisting of an extracellular domain and a noncovalently linked intracellular domain (ICD). Upon interaction with the DSL family of proteins (Jagged, Delta-like) on neighboring cells, Notch undergoes proteolytic cleavage, which frees the ICD from the plasma membrane. This results in translocation of the ICD into the nucleus, where it forms a complex with the CSL family of transcriptional repressors (CBF1/RBP-Jk), removing the repression and allowing for target gene (Hes, Hey) transcription.1,2 Tissue distribution of the Notch proteins varies widely. Notch1 and -4 are predominantly endothelial, prominent in both arteries and veins, and present in all stages of development (embryonic to adult); the expression of Notch2 is typically confined to pulmonary endothelium, but Notch3 is primarily expressed in adult arterial vascular smooth muscle cells (VSMCs) in large conduit, pulmonary, and systemic resistance arteries.3 This specific pattern of temporal and spatial distribution correlate to diverse functions of the Notch family in vascular development and physiology in vertebrates reported to date.4 In the cardiovascular system, Notch signaling plays a role in several aspects of vascular development, including vasculogenesis, angiogenesis, differentiation, vascular remodeling, and VSMC maturation. Notch1 and -4 signaling appears critical in vasculogenesis and angiogenesis during early development, when it interacts with vascular endothelial growth factor signaling to specify artery–vein differentiation of endothelial cells (ECs). Transgenic mice deficient for Notch1 fail to undergo embryonic angiogenic remodeling, and vascular development is arrested at the primitive undifferentiated plexus, resulting in an embryonic lethal phenotype. Notch2-null mutations likewise result in embryonic lethality characterized by multiple large and small vessel aneurysms. Notch4 deletion results in no obvious phenotypic alteration. Notch3−/− mice are viable; however, they fail to develop proper arterial VSMC phenotype, resulting in vein-like …

Induction of Neutrophil Gelatinase-Associated Lipocalin in Vascular Injury via Activation of Nuclear Factor-κB

The Human Genome Project was barely completed in 2003 before a new quest was launched: this time, in a search for short stretches of RNA called microRNA. The belief that these miniature molecules, which had only been discovered a decade earlier, were major regulators of genetic function gained momentum in the intervening years and sparked a worldwide interest in the physiologic and pathologic roles of microRNAs in the human body. These single-stranded, noncoding molecules of RNA, spanning to lengths of only 25 nucleotides, appear to modulate a range of cellular events by modifying the primary function of messenger RNA (mRNA): protein synthesis. The first regulatory RNA, lin-4, was discovered by Victor Ambros in 1993. Later, Andy Fire, Craig Mello, and David Baulcombe discovered small interfering RNA (siRNAs) and established the role of small noncoding mRNA in regulating cell function under a variety of conditions. The field has exploded in directions that no one could have predicted. We now know that small RNAs are expressed in most eukaryotic cells and regulate a remarkable number of cellular functions.1 The exact mechanism of action of microRNAs is unclear; however, it is believed that these molecules bind to select, noncoding regions of mRNA through traditional Watson and Crick base pairing, repressing or increasing expression of the genetic transcript and its corresponding protein. It is theorized that each molecule of microRNA regulates more than 100 distinct molecules of mRNA, with unknown but potentially far-reaching effects in the human body.2 Already multiple reports implicate an array of distinct microRNAs in cardiac and skeletal muscle myogenesis, apoptosis, regeneration, hypertrophy, fibrosis, and cardiac function. Investigators use microRNA expression profiling to identify specific microRNAs in a host of human and animal cells. Quantitative mass spectrometry measures protein levels in cells following the introduction of a specific microRNA …

Binding and functional pharmacological characteristics of gepant-type antagonists in rat brain and mesenteric arteries

Objective To investigate the effect of hypoxia on endothelial growth factor (VEGF) expression in vascular intimal smooth muscle cells (VSMC) and function of VSMC of swine models of brain arteriovenous malformations (BAVM). Methods The stable swine models of BAVM were established; separation of cerebral microvascular network (RM) was performed and VSMC was selected and primarily cultured. VSMC from the above models and normal swines were divided into four groups: group A, VSMC from normal swines cultured at 21% O2; group B, VSMC from models cultured at 21% O2; group C, VSMC from normal swines cultured at 1% O2; group D, VSMC from models cultured at 1% O2. Quantitative real-time polymerase chain reaction (RT-PCR) and Western blotting were used to validate the mRNA and protein VEGF expressions in VSMC; TUNNEL was used to detect the apoptosis of VSMC, and Transwell assay was used to determine the VSMC invasion. Results (1) VSMC density in the four groups was 71.65±4.22, 158.24±9.87, 95.33±7.21 and 299.80±13.23 cells/field in group A-D, with significant differences (F=119.351, P=0.000). (2) VEGF mRNA expression quantity in the four groups was 1.93±0.77, 4.51±1.25, 2.87±1.94 and 8.03±1.74 in group A-D, with significant differences (F=119.351, P=0.000); that in group B-D was significantly higher than that in group A (P 0.05); at the 72 h, the number of apoptosis and invasion cells in group A was significantly decreased as compared with those in group B, C and D (P<0.05). Conclusion Hypoxia can increase the VEGF expression, aggravate the apoptosis and invasion of VSMC, and accelerate the formation of vascular malformation in BAVM models. Key words: Hypoxia; Endangium; Vascular smooth muscle cell; Vascular endothelial growth factor

Cadherins are a superfamily of intercellular adhesion molecules essential for structural maintenance of tissue cohesion, precise primary tissue segregation and regulation of regeneration processes in adult. Cadherins are widely expressed in the vasculature. Adherens junctions and desmosomes, where cadherins are the intercellular adhesion transmembrane linkers, have been demonstrated in large and small arteries in vivo and their participation in correct organization of vascular smooth muscle architecture is doubtless. However, knowledge on precise functional roles for cadherin in healthy or diseased vascular smooth muscle is limited. T-cadherin is an atypical cadherin highly expressed on endothelial and smooth muscle layers of the vasculature. Dynamic T-cadherin expression on vascular smooth muscle in vivo has been reported in number of vascular pathologies including two major vasoproliferative disorders – atherosclerosis and restenosis. Functions and molecular mechanisms regulated by this molecule in the smooth muscle cell component of the vasculature are unknown. The primary functions of vascular smooth muscle cells (VSMC) are contraction and regulation of blood vessel tone. However, VSMC possess inherent plasticity: they can switch from mature contractile phenotype to a de-differentiated proliferative and synthetic phenotype in response to vascular injury, or local environmental cues signalling. Studies in this dissertation are aimed at establishing cellular functions for T-cadherin in VSMC contraction and phenotype plasticity and identifying mediating molecular mechanisms. First, we found that T-cadherin modulates non-metabolic insulin signalling via Akt/mTOR, which in turn leads to alterations in VSMC contractile competence and increased matrix remodelling. T-cadherin overexpressing cells exhibited elevated constitutive levels of phosphorylated Aktser473, GSK3βser9, S6RPser235/236 and IRS-1ser636/639. Contractile machinery was constitutively altered in a manner indicative of reduced intrinsic contractile competence, namely decreased phosphorylation of MYPT1thr696 or MYPT1thr853 and MLC20thr18/ser19, reduced RhoA activity and increased iNOS expression. T-cadherin overexpressing VSMC-populated collagen lattices exhibited greater compaction which was due to increased collagen fibril packing/reorganization. These cells also exhibited a state of insulin insensitivity as evidenced by attenuation of the ability of insulin to stimulate Akt/mTOR axis signalling, phosphorylation of MLC20 and MYPT1, compaction of free-floating lattices and collagen fibril reorganization in unreleased lattices. Second, T-cadherin upregulation on VSMC, a phenomenon observed in VSMC-driven vascular pathologies (atherosclerosis and restenosis) promotes VSMC phenotype transition. T-cadherin upregulation in VSMC caused loss of spindle morphology, reduced/disorganized stress fibre formation, decay of SMC-differentiation marker proteins, increased levels of β-catenin and cyclin D1, and migro-proliferative behaviour. Genetic T-cadherin ablation, on the other hand, enforced differentiated phenotype. T-cadherin hyperactivates Akt axis signalling and inactivates classical downstream effector GSK3β. Ectopic adenoviral-mediated co-expression of constitutively active GSK3β restored morphological, molecular, and functional characteristics of differentiated VSMC in T-cadherin overexpressing cells, suggesting that GSK3β inactivation is essential for T-cadherin induced VSMC de-differentiation. The studies have revealed novel cadherin-based modalities to regulate VSMC sensitivity to insulin and phenotype plasticity, which is achieved via Akt/mTOR axis hyperactivation and altered downstream effector signalling.

Diabetes mellitus is associated with an increased risk of micro and macrovascular complications. During hyperglycemic conditions, endothelial cells and vascular smooth muscle cells are exquisitely sensitive to high glucose. This high glucose-induced sustained reactive oxygen species production leads to redox imbalance, which is associated with endothelial dysfunction and vascular wall remodeling. Nrf2, a redox-regulated transcription factor plays a key role in the antioxidant response element (ARE)-mediated expression of antioxidant genes. Although accumulating data indicate the molecular mechanisms underpinning the Nrf2 regulated redox balance, understanding the influence of the Nrf2/ARE axis during hyperglycemic condition on vascular cells is paramount. This review focuses on the context-dependent role of Nrf2/ARE signaling on vascular endothelial and smooth muscle cell function during hyperglycemic conditions. This review also highlights improving the Nrf2 system in vascular tissues, which could be a potential therapeutic strategy for vascular dysfunction.

Although hypertrophy and hyperplasia of adipocytes as well as increased synthesis and release of adipokines are commonly observed in obesity, a condition associated with insulin resistance and endothelial dysfunction, it is extremely important to understand the biological effects of adipokines, or more specifically of the adipokine chemerin, in nonpathological conditions,. The mechanisms by which cytokines released by the adipose tissue may interfere with vascular function are not yet fully understood. Furthermore, the effects of the cytokine/adipokine chemerin on vascular function are not known. Considering that the chemerin receptor is expressed by vascular smooth muscle and endothelial cells, this study investigated the effects produced by this cytokine in vascular reactivity, as well as the mechanisms by which it modifies vascular function in non-obese animals. Our working hypothesis is that chemerin enhances vascular reactivity to constrictor stimuli, such as endothelin-1(ET-1) and phenylephrine (Phe), and decreases the vasodilation induced by acetylcholine (ACh) and sodium nitroprussiate (SNP). Our specific aims were to determine: 1) whether chemerin induces changes in vascular reactivity, 2) if the alterations of vascular reactivity induced by chemerin are mediated by changes in the function of endothelial cells or vascular smooth muscle cells, 3) which signaling pathways (focus on the MAPKs pathway) are being modified by chemerin and how they contribute to changes in vascular reactivity produced by this cytokine. Our study showed that the adipokine chemerin has biological and cellular activity in aortas from non-obese rats. Chemerin increased vascular responses to contractile stimuli (ET-1 and PhE), producing effects both in the endothelial and vascular smooth muscle cells. The increased contractile responses to ET-1 and PhE were mediated via activation of MEK-ERK1/2, COX-1 and COX-2 and increased expression of the ETA and ETB receptors. Furthermore, this adipokine reduced the vasodilation induced by ACh via eNOS uncoupling and oxidative stress, and by SNP, via effects in the enzyme guanylate cyclase. Our studies may contribute to a better understanding of the role of factors released by the visceral adipose tissue on vascular function and, consequently, on the vascular lesions in obesity and obesity-associated diseases.

Tetrahydropalmatine (THP) regulates mitochondrial function in vascular smooth muscle cells (VSMCs) to prevent or alleviate atherosclerosis (AS), with unclear specific mechanism. AS models were constructed by oxidized low-density lipoprotein (ox-LDL)-treated VSMCs. Cell counting kit-8 for cell viability, wound scratch assay for cell migration, and flow cytometry for cell cycle, intracellular reactive oxygen species, and mitochondrial membrane potential (MMP) were performed. Malondialdehyde (MDA) and superoxide dismutase (SOD) levels by biochemical kits, oxygen consumption rate (OCR) by seahorse apparatus, apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay (TUNEL) staining, and apoptosis-related expression by western blot were detected. Ras homolog gene family A/Rho-associated protein kinase-1 (RhoA/ROCK1) levels were measured by western blot and ELISA. The RhoA agonist, U46619, was employed to validate mechanism of THP. THP suppressed cell cycle progression and cell migration whereas alleviating cell viability and oxidative stress, as reduced MDA and enhanced SOD levels in ox-LDL-incubated VSMCs. THP protected mitochondrial function by higher MMP levels and OCR values. Additionally, THP decreased TUNEL-positive cells, Bax, Caspase-3, RhoA, ROCK1, and osteopontin expression, while increased Bcl-2 and smooth muscle myosin heavy chain levels. Furthermore, U46619 intervention antagonized effects of THP. THP improved mitochondrial function in VSMCs of AS by inhibiting RhoA/ROCK1 signaling pathway.

Cardiac, skeletal, and smooth muscle cells shared the common feature of contraction in response to different stimuli. Agonist-induced muscle's contraction is triggered by a cytosolic free Ca2+ concentration increase due to a rapid Ca2+ release from intracellular stores and a transmembrane Ca2+ influx, mainly through L-type Ca2+ channels. Compelling evidences have demonstrated that Ca2+ might also enter through other cationic channels such as Store-Operated Ca2+ Channels (SOCCs), involved in several physiological functions and pathological conditions. The opening of SOCCs is regulated by the filling state of the intracellular Ca2+ store, the sarcoplasmic reticulum, which communicates to the plasma membrane channels through the Stromal Interaction Molecule 1/2 (STIM1/2) protein. In muscle cells, SOCCs can be mainly non-selective cation channels formed by Orai1 and other members of the Transient Receptor Potential-Canonical (TRPC) channels family, as well as highly selective Ca2+ Release-Activated Ca2+ (CRAC) channels, formed exclusively by subunits of Orai proteins likely organized in macromolecular complexes. This review summarizes the current knowledge of the complex role of Store Operated Calcium Entry (SOCE) pathways and related proteins in the function of cardiac, skeletal, and vascular smooth muscle cells.

JE is a member of the family of "immediate early" genes induced by growth factors and cytokines. JE encodes a low molecular weight secretory glycoprotein analogous to the human monocyte chemoattractant protein, MCP-1. JE and MCP-1 proteins are thought to play an important role in inflammation and in the recruitment of monocyte/macrophages to the vessel wall during the development of atherosclerosis. We have previously reported that the induction of JE in rat aortic smooth muscle cells (SMC) was specific to platelet-derived growth factor (PDGF) and was not seen with other growth agonists. Using a luciferase reporter system and transient transfection assays of rat aortic SMC, we now report the identification of a region in the proximal rat JE promoter that is responsive to PDGF but not to other growth factors (angiotensin II and alpha-thrombin) or cytokines (interleukin 1-beta and tumor necrosis factor-alpha). The full response to PDGF (approximately 6-fold) requires the cooperative activity of two potentially novel cis-acting elements, at positions -146 to -128 and -84 to -59. While each element produces a different pattern in electrophoretic mobility shift assays, they appear to bind the same PDGF-responsive species. Further analysis of these regions should provide important insights into PDGF-specific responses in vascular SMC.

"Cre"ating New Tools for Smooth Muscle Analysis.

The small G protein RhoA is a convergence point for multiple signals that regulate smooth muscle cell functions. NO plays a major role in the structure and function of the normal adult vessel wall, mainly through modulation of gene transcription. This study was thus performed to analyze in vitro and in vivo the effect of NO signaling on RhoA expression in arterial smooth muscle cells. In rat or human artery smooth muscle cells, sodium nitroprusside or 8-(2-chlorophenylthio)-cGMP induced a rise in RhoA mRNA and protein expression, which was inhibited by the cGMP-dependent protein kinase (PKG) inhibitor (R(p))-8-bromo-beta-phenyl-1,N(2)-ethenoguanosine 3':5'-phosphorothioate. The NO/PKG stimulation of RhoA expression involved both an increase in RhoA protein stability and stimulation of rhoA gene transcription. Cloning and functional analysis of the human rhoA promoter revealed that the effect of NO/PKG involved phosphorylation of ATF-1 and subsequent binding to the cAMP-response element. Chronic inhibition of NO synthesis in N(omega)-nitro-l-arginine-treated rats induced a strong decrease in RhoA mRNA and protein expression in aorta and pulmonary artery associated with inhibition of RhoA-mediated Ca(2+) sensitization. These effects were prevented by oral administration of the cGMP phosphodiesterase inhibitor sildenafil. These results show that NO/PKG signaling positively controls RhoA expression and suggest that the basal release of NO is necessary to maintain RhoA expression and RhoA-dependent functions in vascular smooth muscle cells.

Schmid and coworkers1 were the first to report on the presence of heme oxygenase (HO) in liver microsomes capable of degrading heme to bilirubin, and this activity was subsequently dissociated from cytochrome P-450.2,3 HO catalyzes the first and rate-limiting step in the oxidative degradation of heme (Fe-protoporphyrin-IX) to carbon monoxide (CO), ferrous iron (Fe2+), and biliverdin-IX (Figure 1). The enzyme binds heme in a 1:1 molar complex, and HO-bound heme acts as prosthetic group and substrate. The reaction requires 3 molecules of molecular oxygen (O2) per heme molecule oxidized and reducing equivalents derived from nicotinamide adenine dinucleotide phosphate or nicotinamide adenine dinucleotide (reduced form) and transferred to the oxygenase via nicotinamide adenine dinucleotide phosphate:cytochrome P-450 reductase. Regiospecific oxidation of heme is achieved in a stepwise reaction, with α-meso-hydroxyheme and verdoheme as intermediates, and the dissociation of CO followed by that of Fe2+.4 The release of biliverdin from HO is accelerated by biliverdin reductase, which reduces the green pigment to bilirubin-IX,4 which is then excreted into bile as the glucuronic acid conjugate. Figure 1. Oxidative metabolism of heme by HO and biliverdin reductase, giving rise to CO, iron, biliverdin, and bilirubin. Originally, the interest in HO was related to its well-established function in heme catabolism and the turnover of erythrocytes. For many years, CO and bilirubin were regarded as toxic waste byproducts of the HO reaction, but in 1987, a potential beneficial role of bilirubin was proposed5 based on the in vitro antioxidant activities of the pigment. Over the last decade, however, the interest in HO has shifted greatly from a metabolic to a protective function of the enzyme in a variety of conditions associated with cellular stress and pathologies, and this has been the subject of excellent recent reviews.6,7 The …

Previous studies suggested the zinc-finger transcription factor GATA-6 inhibits vascular smooth muscle cell (VSMC) proliferation and promotes the contractile VSMC phenotype. The objective of this study was to identify bona fide target genes regulated by GATA-6 in VSMCs. Microarray analyses were performed comparing mRNA from rat aortic smooth muscle cells (SMCs) infected with either adenovirus encoding a dominant-negative GATA-6/engrailed fusion protein or with control adenovirus. These studies identified 122 genes differentially expressed by at least 2-fold, including multiple genes involved in cell-cell signaling and cell-matrix interactions. Among these, endothelin-1 and the angiotensin type(1a) (AT(1a)) receptor are known to be induced in VSMCs in response to inflammatory stimuli and to be expressed in a GATA-dependent manner in cardiac myocytes in response to hemodynamic stress. Consistent with these findings, the endothelin-1 and AT(1a) receptor promoters were activated by forced expression of GATA-6 and repressed by forced expression of GATA-6/engrailed. Surprisingly, genes encoding SMC contractile proteins were not altered, and myocardin-induced SMC differentiation was not impaired in GATA-6(-/-) embryonic stem cells. These data demonstrate that in VSMCs, GATA-6 regulates a set of genes associated with synthetic SMC functions and suggest that this transcriptional pathway may be independent from myocardin-induced SMC differentiation. An unbiased microarray screen of genes regulated by GATA-6 in VSMCs identified multiple genes involved in cell-cell signaling and cell-matrix interactions. The endothelin-1 and the AT1a receptor genes were shown to be direct GATA-6 target genes. These data suggest that GATA-6 plays a role in promoting synthetic functions in VSMCs.