Browsing by Subject "Carotid Arteries"
Now showing 1 - 7 of 7
- Results Per Page
- Sort Options
Item Open Access Cigarette smoke modulates vascular smooth muscle phenotype: implications for carotid and cerebrovascular disease.(PloS one, 2013-01) Starke, Robert M; Ali, Muhammad S; Jabbour, Pascal M; Tjoumakaris, Stavropoula I; Gonzalez, Fernando; Hasan, David M; Rosenwasser, Robert H; Owens, Gary K; Koch, Walter J; Dumont, Aaron SBackground
The role of smooth muscle cell (SMC) phenotypic modulation in the cerebral circulation and pathogenesis of stroke has not been determined. Cigarette smoke is a major risk factor for atherosclerosis, but potential mechanisms are unclear, and its role in SMC phenotypic modulation has not been established.Methods and results
In cultured cerebral vascular SMCs, exposure to cigarette smoke extract (CSE) resulted in decreased promoter activity and mRNA expression of key SMC contractile genes (SM-α-actin, SM-22α, SM-MHC) and the transcription factor myocardin in a dose-dependent manner. CSE also induced pro-inflammatory/matrix remodeling genes (MCP-1, MMPs, TNF-α, IL-1β, NF-κB). CSE increased expression of KLF4, a known regulator of SMC differentiation, and siKLF4 inhibited CSE induced suppression of SMC contractile genes and myocardin and activation of inflammatory genes. These mechanisms were confirmed in vivo following exposure of rat carotid arteries to CSE. Chromatin immune-precipitation assays in vivo and in vitro demonstrated that CSE promotes epigenetic changes with binding of KLF4 to the promoter regions of myocardin and SMC marker genes and alterations in promoter acetylation and methylation.Conclusion
CSE exposure results in phenotypic modulation of cerebral SMC through myocardin and KLF4 dependent mechanisms. These results provides a mechanism by which cigarette smoke induces a pro-inflammatory/matrix remodeling phenotype in SMC and an important pathway for cigarette smoke to contribute to atherosclerosis and stroke.Item Open Access Geographic variation and trends in carotid imaging among medicare beneficiaries, 2001 to 2006.(Circulation. Cardiovascular quality and outcomes, 2010-11) Curtis, LH; Greiner, MA; Patel, MR; Duncan, PW; Schulman, KA; Matchar, DBBackground
Diagnostic imaging among Medicare beneficiaries is an important contributor to rising health care costs. We examined temporal trends and geographic variation in the use of carotid ultrasound, carotid magnetic resonance angiography (MRA), and carotid x-ray angiography.Methods and results
Analysis of a 5% national sample of claims from the Centers for Medicare and Medicaid Services for 1999 through 2006. Patients were 65 years or older and underwent carotid ultrasound, carotid MRA, carotid x-ray angiography, or a carotid intervention. The main outcome measures were annual age-adjusted rates of carotid imaging and interventions and factors associated with the use of carotid imaging. Rates of imaging increased by 27%, from 98.2 per 1000 person-years in 2001 to 124.3 per 1000 in 2006. Rates of carotid ultrasound increased by 23%, and rates of MRA increased by 66%. Carotid intervention rates decreased from 3.6 per 1000 person-years in 2001 to 3.1 per 1000 person-years in 2006. In 2006, rates of carotid ultrasound were lowest in the New England, Mountain, and West North Central regions and highest in the Middle Atlantic and South Atlantic regions. Regional differences persisted after adjustment for patient demographic characteristics, history of vascular disease and other comorbid conditions, and study year.Conclusions
From 2001 through 2006, there was substantial growth and variation in the use of carotid imaging, including a marked increase in the use of MRA, and a decrease in the overall rate of carotid intervention.Item Open Access Kalirin promotes neointimal hyperplasia by activating Rac in smooth muscle cells.(Arteriosclerosis, thrombosis, and vascular biology, 2013-04) Wu, Jiao-Hui; Fanaroff, Alexander C; Sharma, Krishn C; Smith, Liisa S; Brian, Leigh; Eipper, Betty A; Mains, Richard E; Freedman, Neil J; Zhang, LishengObjective
Kalirin is a multifunctional protein that contains 2 guanine nucleotide exchange factor domains for the GTPases Rac1 and RhoA. Variants of KALRN have been associated with atherosclerosis in humans, but Kalirin's activity has been characterized almost exclusively in the central nervous system. We therefore tested the hypothesis that Kalirin functions as a Rho-guanine nucleotide exchange factor in arterial smooth muscle cells (SMCs).Approach and results
Kalirin-9 protein is expressed abundantly in aorta and bone marrow, as well as in cultured SMCs, endothelial cells, and macrophages. Moreover, arterial Kalirin was upregulated during early atherogenesis in apolipoprotein E-deficient mice. In cultured SMCs, signaling was affected similarly in 3 models of Kalirin loss-of-function: heterozygous Kalrn deletion, Kalirin RNAi, and treatment with the Kalirin Rho-guanine nucleotide exchange factor -1 inhibitor 1-(3-nitrophenyl)-1H-pyrrole-2,5-dione. With reduced Kalirin function, SMCs showed normal RhoA activation but diminished Rac1 activation, assessed as reduced Rac-GTP levels, p21-activated kinase autophosphorylation, and SMC migration. Kalrn(-/+) SMCs proliferated 30% less rapidly than wild-type SMCs. Neointimal hyperplasia engendered by carotid endothelial denudation was ≈60% less in Kalrn(-/+) and SMC-specific Kalrn(-/+) mice than in control mice.Conclusions
Kalirin functions as a guanine nucleotide exchange factor for Rac1 in SMCs, and promotes SMC migration and proliferation both in vitro and in vivo.Item Open Access Phosphorylation of USP20 on Ser334 by IRAK1 promotes IL-1β-evoked signaling in vascular smooth muscle cells and vascular inflammation.(The Journal of biological chemistry, 2023-07) Zhang, Lisheng; Wu, Jiao-Hui; Jean-Charles, Pierre-Yves; Murali, Pavitra; Zhang, Wenli; Jazic, Aeva; Kaur, Suneet; Nepliouev, Igor; Stiber, Jonathan A; Snow, Kamie; Freedman, Neil J; Shenoy, Sudha KReversible lysine-63 (K63) polyubiquitination regulates proinflammatory signaling in vascular smooth muscle cells (SMCs) and plays an integral role in atherosclerosis. Ubiquitin-specific peptidase 20 (USP20) reduces NFκB activation triggered by proinflammatory stimuli, and USP20 activity attenuates atherosclerosis in mice. The association of USP20 with its substrates triggers deubiquitinase activity; this association is regulated by phosphorylation of USP20 on Ser334 (mouse) or Ser333 (human). USP20 Ser333 phosphorylation was greater in SMCs of atherosclerotic segments of human arteries as compared with nonatherosclerotic segments. To determine whether USP20 Ser334 phosphorylation regulates proinflammatory signaling, we created USP20-S334A mice using CRISPR/Cas9-mediated gene editing. USP20-S334A mice developed ∼50% less neointimal hyperplasia than congenic WT mice after carotid endothelial denudation. WT carotid SMCs showed substantial phosphorylation of USP20 Ser334, and WT carotids demonstrated greater NFκB activation, VCAM-1 expression, and SMC proliferation than USP20-S334A carotids. Concordantly, USP20-S334A primary SMCs in vitro proliferated and migrated less than WT SMCs in response to IL-1β. An active site ubiquitin probe bound to USP20-S334A and USP20-WT equivalently, but USP20-S334A associated more avidly with TRAF6 than USP20-WT. IL-1β induced less K63-linked polyubiquitination of TRAF6 and less downstream NFκB activity in USP20-S334A than in WT SMCs. Using in vitro phosphorylation with purified IRAK1 and siRNA-mediated gene silencing of IRAK1 in SMCs, we identified IRAK1 as a novel kinase for IL-1β-induced USP20 Ser334 phosphorylation. Our findings reveal novel mechanisms regulating IL-1β-induced proinflammatory signaling: by phosphorylating USP20 Ser334, IRAK1 diminishes the association of USP20 with TRAF6 and thus augments NFκB activation, SMC inflammation, and neointimal hyperplasia.Item Open Access Targeting Gbeta gamma signaling in arterial vascular smooth muscle proliferation: a novel strategy to limit restenosis.(Proc Natl Acad Sci U S A, 1999-03-30) Iaccarino, G; Smithwick, LA; Lefkowitz, RJ; Koch, WJRestenosis continues to be a major problem limiting the effectiveness of revascularization procedures. To date, the roles of heterotrimeric G proteins in the triggering of pathological vascular smooth muscle (VSM) cell proliferation have not been elucidated. betagamma subunits of heterotrimeric G proteins (Gbetagamma) are known to activate mitogen-activated protein (MAP) kinases after stimulation of certain G protein-coupled receptors; however, their relevance in VSM mitogenesis in vitro or in vivo is not known. Using adenoviral-mediated transfer of a transgene encoding a peptide inhibitor of Gbetagamma signaling (betaARKct), we evaluated the role of Gbetagamma in MAP kinase activation and proliferation in response to several mitogens, including serum, in cultured rat VSM cells. Our results include the striking finding that serum-induced proliferation of VSM cells in vitro is mediated largely via Gbetagamma. Furthermore, we studied the effects of in vivo adenoviral-mediated betaARKct gene transfer on VSM intimal hyperplasia in a rat carotid artery restenosis model. Our in vivo results demonstrated that the presence of the betaARKct in injured rat carotid arteries significantly reduced VSM intimal hyperplasia by 70%. Thus, Gbetagamma plays a critical role in physiological VSM proliferation, and targeted Gbetagamma inhibition represents a novel approach for the treatment of pathological conditions such as restenosis.Item Open Access The Actin-Binding Protein Drebrin Inhibits Neointimal Hyperplasia.(Arteriosclerosis, thrombosis, and vascular biology, 2016-05) Stiber, Jonathan A; Wu, Jiao-Hui; Zhang, Lisheng; Nepliouev, Igor; Zhang, Zhu-Shan; Bryson, Victoria G; Brian, Leigh; Bentley, Rex C; Gordon-Weeks, Phillip R; Rosenberg, Paul B; Freedman, Neil JObjective
Vascular smooth muscle cell (SMC) migration is regulated by cytoskeletal remodeling as well as by certain transient receptor potential (TRP) channels, nonselective cation channels that modulate calcium influx. Proper function of multiple subfamily C TRP (TRPC) channels requires the scaffolding protein Homer 1, which associates with the actin-binding protein Drebrin. We found that SMC Drebrin expression is upregulated in atherosclerosis and in response to injury and investigated whether Drebrin inhibits SMC activation, either through regulation of TRP channel function via Homer or through a direct effect on the actin cytoskeleton.Approach and results
Wild-type (WT) and congenic Dbn(-/+) mice were subjected to wire-mediated carotid endothelial denudation. Subsequent neointimal hyperplasia was 2.4±0.3-fold greater in Dbn(-/+) than in WT mice. Levels of globular actin were equivalent in Dbn(-/+) and WT SMCs, but there was a 2.4±0.5-fold decrease in filamentous actin in Dbn(-/+) SMCs compared with WT. Filamentous actin was restored to WT levels in Dbn(-/+) SMCs by adenoviral-mediated rescue expression of Drebrin. Compared with WT SMCs, Dbn(-/+) SMCs exhibited increased TRP channel activity in response to platelet-derived growth factor, increased migration assessed in Boyden chambers, and increased proliferation. Enhanced TRP channel activity and migration in Dbn(-/+) SMCs were normalized to WT levels by rescue expression of not only WT Drebrin but also a mutant Drebrin isoform that binds actin but fails to bind Homer.Conclusions
Drebrin reduces SMC activation through its interaction with the actin cytoskeleton but independently of its interaction with Homer scaffolds.Item Open Access TNF-α induces phenotypic modulation in cerebral vascular smooth muscle cells: implications for cerebral aneurysm pathology.(Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism, 2013-10) Ali, Muhammad S; Starke, Robert M; Jabbour, Pascal M; Tjoumakaris, Stavropoula I; Gonzalez, L Fernando; Rosenwasser, Robert H; Owens, Gary K; Koch, Walter J; Greig, Nigel H; Dumont, Aaron SLittle is known about vascular smooth muscle cell (SMC) phenotypic modulation in the cerebral circulation or pathogenesis of intracranial aneurysms. Tumor necrosis factor-alpha (TNF-α) has been associated with aneurysms, but potential mechanisms are unclear. Cultured rat cerebral SMCs overexpressing myocardin induced expression of key SMC contractile genes (SM-α-actin, SM-22α, smooth muscle myosin heavy chain), while dominant-negative cells suppressed expression. Tumor necrosis factor-alpha treatment inhibited this contractile phenotype and induced pro-inflammatory/matrix-remodeling genes (monocyte chemoattractant protein-1, matrix metalloproteinase-3, matrix metalloproteinase-9, vascular cell adhesion molecule-1, interleukin-1 beta). Tumor necrosis factor-alpha increased expression of KLF4, a known regulator of SMC differentiation. Kruppel-like transcription factor 4 (KLF4) small interfering RNA abrogated TNF-α activation of inflammatory genes and suppression of contractile genes. These mechanisms were confirmed in vivo after exposure of rat carotid arteries to TNF-α and early on in a model of cerebral aneurysm formation. Treatment with the synthesized TNF-α inhibitor 3,6-dithiothalidomide reversed pathologic vessel wall alterations after induced hypertension and hemodynamic stress. Chromatin immunoprecipitation assays in vivo and in vitro demonstrated that TNF-α promotes epigenetic changes through KLF4-dependent alterations in promoter regions of myocardin, SMCs, and inflammatory genes. In conclusion, TNF-α induces phenotypic modulation of cerebral SMCs through myocardin and KLF4-regulated pathways. These results demonstrate a novel role for TNF-α in promoting a pro-inflammatory/matrix-remodeling phenotype, which has important implications for the mechanisms behind intracranial aneurysm formation.