1
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Tanaka K, Chen M, Prendergast A, Zhuang Z, Nasiri A, Joshi D, Hintzen J, Chung M, Kumar A, Mani A, Koleske A, Crawford J, Nicoli S, Schwartz MA. Latrophilin-2 mediates fluid shear stress mechanotransduction at endothelial junctions. EMBO J 2024:10.1038/s44318-024-00142-0. [PMID: 38886581 DOI: 10.1038/s44318-024-00142-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 02/20/2024] [Accepted: 05/13/2024] [Indexed: 06/20/2024] Open
Abstract
Endothelial cell responses to fluid shear stress from blood flow are crucial for vascular development, function, and disease. A complex of PECAM-1, VE-cadherin, VEGF receptors (VEGFRs), and Plexin D1 located at cell-cell junctions mediates many of these events. However, available evidence suggests that another mechanosensor upstream of PECAM-1 initiates signaling. Hypothesizing that GPCR and Gα proteins may serve this role, we performed siRNA screening of Gα subunits and found that Gαi2 and Gαq/11 are required for activation of the junctional complex. We then developed a new activation assay, which showed that these G proteins are activated by flow. We next mapped the Gα residues required for activation and developed an affinity purification method that used this information to identify latrophilin-2 (Lphn2/ADGRL2) as the upstream GPCR. Latrophilin-2 is required for all PECAM-1 downstream events tested. In both mice and zebrafish, latrophilin-2 is required for flow-dependent angiogenesis and artery remodeling. Furthermore, endothelial-specific knockout demonstrates that latrophilin plays a role in flow-dependent artery remodeling. Human genetic data reveal a correlation between the latrophilin-2-encoding Adgrl2 gene and cardiovascular disease. Together, these results define a pathway that connects latrophilin-dependent G protein activation to subsequent endothelial signaling, vascular physiology, and disease.
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Affiliation(s)
- Keiichiro Tanaka
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT, 06511, USA.
| | - Minghao Chen
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT, 06511, USA
| | - Andrew Prendergast
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT, 06511, USA
| | - Zhenwu Zhuang
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT, 06511, USA
| | - Ali Nasiri
- Department of Internal Medicine, Yale University, New Haven, CT, USA
| | - Divyesh Joshi
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT, 06511, USA
| | - Jared Hintzen
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT, 06511, USA
| | - Minhwan Chung
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT, 06511, USA
| | - Abhishek Kumar
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT, 06511, USA
| | - Arya Mani
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT, 06511, USA
| | - Anthony Koleske
- Department of Molecular Biochemistry and Biophysics, Yale University, New Haven, CT, USA
| | - Jason Crawford
- Department of Chemistry, Yale University, New Haven, CT, USA
| | - Stefania Nicoli
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT, 06511, USA
| | - Martin A Schwartz
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, Yale University, New Haven, CT, 06511, USA.
- Department of Cell Biology, Yale University, New Haven, CT, USA.
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA.
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2
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Tanaka K, Chen M, Prendergast A, Zhuang Z, Nasiri A, Joshi D, Hintzen J, Chung M, Kumar A, Mani A, Koleske A, Crawford J, Nicoli S, Schwartz MA. Latrophilin-2 mediates fluid shear stress mechanotransduction at endothelial junctions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.13.598386. [PMID: 38915515 PMCID: PMC11195282 DOI: 10.1101/2024.06.13.598386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Endothelial cell responses to fluid shear stress from blood flow are crucial for vascular development, function and disease. A complex of PECAM-1, VE-cadherin, VEGF receptors (VEGFRs) and PlexinD1 located at cell-cell junctions mediates many of these events. But available evidence suggests that another mechanosensor upstream of PECAM-1 initiates signaling. Hypothesizing that GPCR and Gα proteins may serve this role, we performed siRNA screening of Gα subunits and found that Gαi2 and Gαq/11 are required for activation of the junctional complex. We then developed a new activation assay, which showed that these G proteins are activated by flow. We next mapped the Gα residues required for activation and developed an affinity purification method that used this information to identify latrophilin-2 (Lphn-2/ADGRL2) as the upstream GPCR. Latrophilin-2 is required for all PECAM-1 downstream events tested. In both mice and zebrafish, latrophilin-2 is required for flow-dependent angiogenesis and artery remodeling. Furthermore, endothelial specific knockout demonstrates that latrophilin plays a role in flow-dependent artery remodeling. Human genetic data reveal a correlation between the latrophilin-2-encoding Adgrl2 gene and cardiovascular disease. Together, these results define a pathway that connects latrophilin-dependent G protein activation to subsequent endothelial signaling, vascular physiology and disease.
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3
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Rokka S, Sadeghinejad M, Hudgins EC, Johnson EJ, Nguyen T, Fancher IS. Visceral adipose of obese mice inhibits endothelial inwardly rectifying K + channels in a CD36-dependent fashion. Am J Physiol Cell Physiol 2024; 326:C1543-C1555. [PMID: 38586877 DOI: 10.1152/ajpcell.00073.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 03/28/2024] [Accepted: 03/29/2024] [Indexed: 04/09/2024]
Abstract
Obesity imposes deficits on adipose tissue and vascular endothelium, yet the role that distinct adipose depots play in mediating endothelial dysfunction in local arteries remains unresolved. We recently showed that obesity impairs endothelial Kir2.1 channels, mediators of nitric oxide production, in arteries of visceral adipose tissue (VAT), while Kir2.1 function in subcutaneous adipose tissue (SAT) endothelium remains intact. Therefore, we determined if VAT versus SAT from lean or diet-induced obese mice affected Kir2.1 channel function in vitro. We found that VAT from obese mice reduces Kir2.1 function without altering channel expression whereas AT from lean mice and SAT from obese mice had no effect on Kir2.1 function as compared to untreated control cells. As Kir2.1 is well known to be inhibited by fatty acid derivatives and obesity is strongly associated with elevated circulating fatty acids, we next tested the role of the fatty acid translocase CD36 in mediating VAT-induced Kir2.1 dysfunction. We found that the downregulation of CD36 restored Kir2.1 currents in endothelial cells exposed to VAT from obese mice. In addition, endothelial cells exposed to VAT from obese mice exhibited a significant increase in CD36-mediated fatty acid uptake. The importance of CD36 in obesity-induced endothelial dysfunction of VAT arteries was further supported in ex vivo pressure myography studies where CD36 ablation rescued the endothelium-dependent response to flow via restoring Kir2.1 and endothelial nitric oxide synthase function. These findings provide new insight into the role of VAT in mediating obesity-induced endothelial dysfunction and suggest a novel role for CD36 as a mediator of endothelial Kir2.1 impairment.NEW & NOTEWORTHY Our findings suggest a role for visceral adipose tissue (VAT) in the dysfunction of endothelial Kir2.1 in obesity. We further reveal a role for CD36 as a major contributor to VAT-mediated Kir2.1 and endothelial dysfunction, suggesting that CD36 offers a potential target for preventing the early development of obesity-associated cardiovascular disease.
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Affiliation(s)
- Sabita Rokka
- Department of Kinesiology and Applied Physiology, College of Health SciencesUniversity of Delaware, Newark, Delaware, United States
| | - Masoumeh Sadeghinejad
- Department of Kinesiology and Applied Physiology, College of Health SciencesUniversity of Delaware, Newark, Delaware, United States
| | - Emma C Hudgins
- Department of Kinesiology and Applied Physiology, College of Health SciencesUniversity of Delaware, Newark, Delaware, United States
| | - Erica J Johnson
- Department of Kinesiology and Applied Physiology, College of Health SciencesUniversity of Delaware, Newark, Delaware, United States
| | - Thanh Nguyen
- Department of Kinesiology and Applied Physiology, College of Health SciencesUniversity of Delaware, Newark, Delaware, United States
| | - Ibra S Fancher
- Department of Kinesiology and Applied Physiology, College of Health SciencesUniversity of Delaware, Newark, Delaware, United States
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4
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Beverley KM, Levitan I. Cholesterol regulation of mechanosensitive ion channels. Front Cell Dev Biol 2024; 12:1352259. [PMID: 38333595 PMCID: PMC10850386 DOI: 10.3389/fcell.2024.1352259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 01/17/2024] [Indexed: 02/10/2024] Open
Abstract
The purpose of this review is to evaluate the role of cholesterol in regulating mechanosensitive ion channels. Ion channels discussed in this review are sensitive to two types of mechanical signals, fluid shear stress and/or membrane stretch. Cholesterol regulates the channels primarily in two ways: 1) indirectly through localizing the channels into cholesterol-rich membrane domains where they interact with accessory proteins and/or 2) direct binding of cholesterol to the channel at specified putative binding sites. Cholesterol may also regulate channel function via changes of the biophysical properties of the membrane bilayer. Changes in cholesterol affect both mechanosensitivity and basal channel function. We focus on four mechanosensitive ion channels in this review Piezo, Kir2, TRPV4, and VRAC channels. Piezo channels were shown to be regulated by auxiliary proteins that enhance channel function in high cholesterol domains. The direct binding mechanism was shown in Kir2.1 and TRPV4 where cholesterol inhibits channel function. Finally, cholesterol regulation of VRAC was attributed to changes in the physical properties of lipid bilayer. Additional studies should be performed to determine the physiological implications of these sterol effects in complex cellular environments.
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Affiliation(s)
- Katie M. Beverley
- Division of Pulmonary, Critical Care, Sleep, and Allergy, Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Irena Levitan
- Division of Pulmonary, Critical Care, Sleep, and Allergy, Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
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5
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Li C, Yang Y. Advancements in the study of inward rectifying potassium channels on vascular cells. Channels (Austin) 2023; 17:2237303. [PMID: 37463317 PMCID: PMC10355679 DOI: 10.1080/19336950.2023.2237303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/20/2023] [Accepted: 07/04/2023] [Indexed: 07/20/2023] Open
Abstract
Inward rectifier potassium channels (Kir channels) exist in a variety of cells and are involved in maintaining resting membrane potential and signal transduction in most cells, as well as connecting metabolism and membrane excitability of body cells. It is closely related to normal physiological functions of body and the occurrence and development of some diseases. Although the functional expression of Kir channels and their role in disease have been studied, they have not been fully elucidated. In this paper, the functional expression of Kir channels in vascular endothelial cells and smooth muscle cells and their changes in disease states were reviewed, especially the recent research progress of Kir channels in stem cells was introduced, in order to have a deeper understanding of Kir channels in vascular tissues and provide new ideas and directions for the treatment of related ion channel diseases.
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Affiliation(s)
- Chunshu Li
- Key Lab of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Lab of Sichuan Province, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Yan Yang
- Key Lab of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Lab of Sichuan Province, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
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6
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Behringer EJ. Impact of aging on vascular ion channels: perspectives and knowledge gaps across major organ systems. Am J Physiol Heart Circ Physiol 2023; 325:H1012-H1038. [PMID: 37624095 PMCID: PMC10908410 DOI: 10.1152/ajpheart.00288.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 08/21/2023] [Accepted: 08/21/2023] [Indexed: 08/26/2023]
Abstract
Individuals aged ≥65 yr will comprise ∼20% of the global population by 2030. Cardiovascular disease remains the leading cause of death in the world with age-related endothelial "dysfunction" as a key risk factor. As an organ in and of itself, vascular endothelium courses throughout the mammalian body to coordinate blood flow to all other organs and tissues (e.g., brain, heart, lung, skeletal muscle, gut, kidney, skin) in accord with metabolic demand. In turn, emerging evidence demonstrates that vascular aging and its comorbidities (e.g., neurodegeneration, diabetes, hypertension, kidney disease, heart failure, and cancer) are "channelopathies" in large part. With an emphasis on distinct functional traits and common arrangements across major organs systems, the present literature review encompasses regulation of vascular ion channels that underlie blood flow control throughout the body. The regulation of myoendothelial coupling and local versus conducted signaling are discussed with new perspectives for aging and the development of chronic diseases. Although equipped with an awareness of knowledge gaps in the vascular aging field, a section has been included to encompass general feasibility, role of biological sex, and additional conceptual and experimental considerations (e.g., cell regression and proliferation, gene profile analyses). The ultimate goal is for the reader to see and understand major points of deterioration in vascular function while gaining the ability to think of potential mechanistic and therapeutic strategies to sustain organ perfusion and whole body health with aging.
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Affiliation(s)
- Erik J Behringer
- Basic Sciences, Loma Linda University, Loma Linda, California, United States
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7
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Polk FD, Hakim MA, Silva JF, Behringer EJ, Pires PW. Endothelial K IR2 channel dysfunction in aged cerebral parenchymal arterioles. Am J Physiol Heart Circ Physiol 2023; 325:H1360-H1372. [PMID: 37801044 PMCID: PMC10907073 DOI: 10.1152/ajpheart.00279.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 09/27/2023] [Accepted: 09/28/2023] [Indexed: 10/07/2023]
Abstract
Aging is associated with cognitive decline via incompletely understood mechanisms. Cerebral microvascular dysfunction occurs in aging, particularly impaired endothelium-mediated dilation. Parenchymal arterioles are bottlenecks of the cerebral microcirculation, and dysfunction causes a mismatch in nutrient demand and delivery, leaving neurons at risk. Extracellular nucleotides elicit parenchymal arteriole dilation by activating endothelial purinergic receptors (P2Y), leading to opening of K+ channels, including inwardly-rectifying K+ channels (KIR2). These channels amplify hyperpolarizing signals, resulting in dilation. However, it remains unknown if endothelial P2Y and KIR2 signaling are altered in brain parenchymal arterioles during aging. We hypothesized that aging impairs endothelial P2Y and KIR2 function in parenchymal arterioles. We observed reduced dilation to the purinergic agonist 2-methyl-S-ADP (1 µM) in arterioles from Aged (>24-month-old) mice when compared to Young (4-6 months of age) despite similar hyperpolarization in endothelial cells tubes. No differences were observed in vasodilation or endothelial cell hyperpolarization to activation of small- and intermediate-conductance Ca2+-activated K+ channels (KCa2.3 / KCa3.1) by NS309. Hyperpolarization to 15 mM [K+]E was smaller in Aged than Young mice, despite a paradoxical increased dilation in Aged arterioles to 15 mM [K+]E that was unchanged by endothelium removal. KIR2 Inhibition attenuated vasodilatory responses to 15 mM [K+]E and 1 µM 2-me-S-ADP in both Young and Aged arterioles. Further, we observed a significant increase in myogenic tone in Aged parenchymal arterioles, which was not enhanced by endothelium removal. We conclude that aging impairs endothelial KIR2 channel function in the cerebral microcirculation with possible compensation by smooth muscle cells.
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Affiliation(s)
- Felipe D Polk
- Department of Physiology, University of Arizona, Tucson, Arizona, United States
| | - Md A Hakim
- Loma Linda University, Loma Linda, CA, United States
| | - Josiane F Silva
- Physiology, University of Arizona, Tucson, Arizona, United States
| | - Erik J Behringer
- Basic Sciences, Loma Linda University, Loma Linda, CA, United States
| | - Paulo W Pires
- Physiology, University of Arizona, Tucson, AZ, United States
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8
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Fancher IS, Levitan I. Membrane Cholesterol Interactions with Proteins in Hypercholesterolemia-Induced Endothelial Dysfunction. Curr Atheroscler Rep 2023; 25:535-541. [PMID: 37418067 PMCID: PMC10471518 DOI: 10.1007/s11883-023-01127-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2023] [Indexed: 07/08/2023]
Abstract
PURPOSE OF REVIEW The goal of this review is to highlight work identifying mechanisms driving hypercholesterolemia-mediated endothelial dysfunction. We specifically focus on cholesterol-protein interactions and address specific questions related to the impact of hypercholesterolemia on cellular cholesterol and vascular endothelial function. We describe key approaches used to determine the effects of cholesterol-protein interactions in mediating endothelial dysfunction under dyslipidemic conditions. RECENT FINDINGS The benefits of removing the cholesterol surplus on endothelial function in models of hypercholesterolemia is clear. However, specific mechanisms driving cholesterol-induced endothelial dysfunction need to be determined. In this review, we detail the latest findings describing cholesterol-mediated endothelial dysfunction, highlighting our studies indicating that cholesterol suppresses endothelial Kir2.1 channels as a major underlying mechanism. The findings detailed in this review support the targeting of cholesterol-induced suppression of proteins in restoring endothelial function in dyslipidemic conditions. The identification of similar mechanisms regarding other cholesterol-endothelial protein interactions is warranted.
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Affiliation(s)
- Ibra S. Fancher
- Department of Kinesiology and Applied Physiology, College of Health Sciences, University of Delaware, Newark, DE USA
| | - Irena Levitan
- Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL USA
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9
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Davis MJ, Earley S, Li YS, Chien S. Vascular mechanotransduction. Physiol Rev 2023; 103:1247-1421. [PMID: 36603156 PMCID: PMC9942936 DOI: 10.1152/physrev.00053.2021] [Citation(s) in RCA: 43] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 09/26/2022] [Accepted: 10/04/2022] [Indexed: 01/07/2023] Open
Abstract
This review aims to survey the current state of mechanotransduction in vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), including their sensing of mechanical stimuli and transduction of mechanical signals that result in the acute functional modulation and longer-term transcriptomic and epigenetic regulation of blood vessels. The mechanosensors discussed include ion channels, plasma membrane-associated structures and receptors, and junction proteins. The mechanosignaling pathways presented include the cytoskeleton, integrins, extracellular matrix, and intracellular signaling molecules. These are followed by discussions on mechanical regulation of transcriptome and epigenetics, relevance of mechanotransduction to health and disease, and interactions between VSMCs and ECs. Throughout this review, we offer suggestions for specific topics that require further understanding. In the closing section on conclusions and perspectives, we summarize what is known and point out the need to treat the vasculature as a system, including not only VSMCs and ECs but also the extracellular matrix and other types of cells such as resident macrophages and pericytes, so that we can fully understand the physiology and pathophysiology of the blood vessel as a whole, thus enhancing the comprehension, diagnosis, treatment, and prevention of vascular diseases.
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Affiliation(s)
- Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Scott Earley
- Department of Pharmacology, University of Nevada, Reno, Nevada
| | - Yi-Shuan Li
- Department of Bioengineering, University of California, San Diego, California
- Institute of Engineering in Medicine, University of California, San Diego, California
| | - Shu Chien
- Department of Bioengineering, University of California, San Diego, California
- Institute of Engineering in Medicine, University of California, San Diego, California
- Department of Medicine, University of California, San Diego, California
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10
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Askari H, Sadeghinejad M, Fancher IS. Mechanotransduction and the endothelial glycocalyx: Interactions with membrane and cytoskeletal proteins to transduce force. CURRENT TOPICS IN MEMBRANES 2023; 91:43-60. [PMID: 37080680 DOI: 10.1016/bs.ctm.2023.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
The endothelial glycocalyx is an extracellular matrix that coats the endothelium and extends into the lumen of blood vessels, acting as a barrier between the vascular wall and blood flowing through the vessel. This positioning of the glycocalyx permits a variety of its constituents, including the major endothelial proteoglycans glypican-1 and syndecan-1, as well as the major glycosaminoglycans heparan sulfate and hyaluronic acid, to contribute to the processes of mechanosensation and subsequent mechanotransduction following such stimuli as elevated shear stress. To coordinate the vast array of processes that occur in response to physical force, the glycocalyx interacts with a plethora of membrane and cytoskeletal proteins to carry out specific signaling pathways resulting in a variety of responses of endothelial cells and, ultimately, blood vessels to mechanical force. This review focuses on proposed glycocalyx-protein relationships whereby the endothelial glycocalyx interacts with a variety of membrane and cytoskeletal proteins to transduce force into a myriad of chemical signaling pathways. The established and proposed interactions at the molecular level are discussed in context of how the glycocalyx regulates membrane/cytoskeletal protein function in the many processes of endothelial mechanotransduction.
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11
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Sytha SP, Self TS, Heaps CL. K + channels in the coronary microvasculature of the ischemic heart. CURRENT TOPICS IN MEMBRANES 2022; 90:141-166. [PMID: 36368873 PMCID: PMC10494550 DOI: 10.1016/bs.ctm.2022.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Ischemic heart disease is the leading cause of death and a major public health and economic burden worldwide with expectations of predicted growth in the foreseeable future. It is now recognized clinically that flow-limiting stenosis of the large coronary conduit arteries as well as microvascular dysfunction in the absence of severe stenosis can each contribute to the etiology of ischemic heart disease. The primary site of coronary vascular resistance, and control of subsequent coronary blood flow, is found in the coronary microvasculature, where small changes in radius can have profound impacts on myocardial perfusion. Basal active tone and responses to vasodilators and vasoconstrictors are paramount in the regulation of coronary blood flow and adaptations in signaling associated with ion channels are a major factor in determining alterations in vascular resistance and thereby myocardial blood flow. K+ channels are of particular importance as contributors to all aspects of the regulation of arteriole resistance and control of perfusion into the myocardium because these channels dictate membrane potential, the resultant activity of voltage-gated calcium channels, and thereby, the contractile state of smooth muscle. Evidence also suggests that K+ channels play a significant role in adaptations with cardiovascular disease states. In this review, we highlight our research examining the role of K+ channels in ischemic heart disease and adaptations with exercise training as treatment, as well as how our findings have contributed to this area of study.
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Affiliation(s)
- Sharanee P Sytha
- Department of Physiology and Pharmacology, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
| | - Trevor S Self
- Department of Physiology and Pharmacology, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
| | - Cristine L Heaps
- Department of Physiology and Pharmacology, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States; Michael E. DeBakey Institute for Comparative Cardiovascular Science and Biomedical Devices, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States.
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12
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Jiang M, Ding H, Huang Y, Wang L. Shear Stress and Metabolic Disorders-Two Sides of the Same Plaque. Antioxid Redox Signal 2022; 37:820-841. [PMID: 34148374 DOI: 10.1089/ars.2021.0126] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Significance: Shear stress and metabolic disorder are the two sides of the same atherosclerotic coin. Atherosclerotic lesions are prone to develop at branches and curvatures of arteries, which are exposed to oscillatory and low shear stress exerted by blood flow. Meanwhile, metabolic disorders are pivotal contributors to the formation and advancement of atherosclerotic plaques. Recent Advances: Accumulated evidence has provided insight into the impact and mechanisms of biomechanical forces and metabolic disorder on atherogenesis, in association with mechanotransduction, epigenetic regulation, and so on. Moreover, recent studies have shed light on the cross talk between the two drivers of atherosclerosis. Critical Issues: There are extensive cross talk and interactions between shear stress and metabolic disorder during the pathogenesis of atherosclerosis. The communications may amplify the proatherogenic effects through increasing oxidative stress and inflammation. Nonetheless, the precise mechanisms underlying such interactions remain to be fully elucidated as the cross talk network is considerably complex. Future Directions: A better understanding of the cross talk network may confer benefits for a more comprehensive clinical management of atherosclerosis. Critical mediators of the cross talk may serve as promising therapeutic targets for atherosclerotic vascular diseases, as they can inhibit effects from both sides of the plaque. Hence, further in-depth investigations with advanced omics approaches are required to develop novel and effective therapeutic strategies against atherosclerosis. Antioxid. Redox Signal. 37, 820-841.
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Affiliation(s)
- Minchun Jiang
- Heart and Vascular Institute, School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China.,Shenzhen Research Institute, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Huanyu Ding
- Heart and Vascular Institute, School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China.,Shenzhen Research Institute, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Yu Huang
- Heart and Vascular Institute, School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China.,Shenzhen Research Institute, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Li Wang
- Heart and Vascular Institute, School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China.,Shenzhen Research Institute, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
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13
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King DR, Sedovy MW, Eaton X, Dunaway LS, Good ME, Isakson BE, Johnstone SR. Cell-To-Cell Communication in the Resistance Vasculature. Compr Physiol 2022; 12:3833-3867. [PMID: 35959755 DOI: 10.1002/cphy.c210040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The arterial vasculature can be divided into large conduit arteries, intermediate contractile arteries, resistance arteries, arterioles, and capillaries. Resistance arteries and arterioles primarily function to control systemic blood pressure. The resistance arteries are composed of a layer of endothelial cells oriented parallel to the direction of blood flow, which are separated by a matrix layer termed the internal elastic lamina from several layers of smooth muscle cells oriented perpendicular to the direction of blood flow. Cells within the vessel walls communicate in a homocellular and heterocellular fashion to govern luminal diameter, arterial resistance, and blood pressure. At rest, potassium currents govern the basal state of endothelial and smooth muscle cells. Multiple stimuli can elicit rises in intracellular calcium levels in either endothelial cells or smooth muscle cells, sourced from intracellular stores such as the endoplasmic reticulum or the extracellular space. In general, activation of endothelial cells results in the production of a vasodilatory signal, usually in the form of nitric oxide or endothelial-derived hyperpolarization. Conversely, activation of smooth muscle cells results in a vasoconstriction response through smooth muscle cell contraction. © 2022 American Physiological Society. Compr Physiol 12: 1-35, 2022.
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Affiliation(s)
- D Ryan King
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, Virginia Tech, Roanoke, Virginia, USA
| | - Meghan W Sedovy
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, Virginia Tech, Roanoke, Virginia, USA.,Translational Biology, Medicine, and Health Graduate Program, Virginia Tech, Blacksburg, Virginia, USA
| | - Xinyan Eaton
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, Virginia Tech, Roanoke, Virginia, USA
| | - Luke S Dunaway
- Robert M. Berne Cardiovascular Research Centre, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Miranda E Good
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, Massachusetts, USA
| | - Brant E Isakson
- Robert M. Berne Cardiovascular Research Centre, University of Virginia School of Medicine, Charlottesville, Virginia, USA.,Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Scott R Johnstone
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, Virginia Tech, Roanoke, Virginia, USA.,Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
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14
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Hudgins EC, Bonar AM, Nguyen T, Fancher IS. Targeting Lipid—Ion Channel Interactions in Cardiovascular Disease. Front Cardiovasc Med 2022; 9:876634. [PMID: 35600482 PMCID: PMC9120415 DOI: 10.3389/fcvm.2022.876634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 04/19/2022] [Indexed: 11/23/2022] Open
Abstract
General lipid-lowering strategies exhibit clinical benefit, however, adverse effects and low adherence of relevant pharmacotherapies warrants the investigation into distinct avenues for preventing dyslipidemia-induced cardiovascular disease. Ion channels play an important role in the maintenance of vascular tone, the impairment of which is a critical precursor to disease progression. Recent evidence suggests that the dysregulation of ion channel function in dyslipidemia is one of many contributors to the advancement of cardiovascular disease thus bringing to light a novel yet putative therapeutic avenue for preventing the progression of disease mechanisms. Increasing evidence suggests that lipid regulation of ion channels often occurs through direct binding of the lipid with the ion channel thereby creating a potential therapeutic target wherein preventing specific lipid-ion channel interactions, perhaps in combination with established lipid lowering therapies, may restore ion channel function and the proper control of vascular tone. Here we first detail specific examples of lipid-ion channel interactions that promote vascular dysfunction and highlight the benefits of preventing such interactions. We next discuss the putative therapeutic avenues, such as peptides, monoclonal antibodies, and aspects of nanomedicine that may be utilized to prevent pathological lipid-ion channel interactions. Finally, we discuss the experimental challenges with identifying lipid-ion channel interactions as well as the likely pitfalls with developing the aforementioned putative strategies.
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15
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Sabe SA, Feng J, Sellke FW, Abid MR. Mechanisms and clinical implications of endothelium-dependent vasomotor dysfunction in coronary microvasculature. Am J Physiol Heart Circ Physiol 2022; 322:H819-H841. [PMID: 35333122 PMCID: PMC9018047 DOI: 10.1152/ajpheart.00603.2021] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 03/21/2022] [Accepted: 03/21/2022] [Indexed: 12/16/2022]
Abstract
Coronary microvascular disease (CMD), which affects the arterioles and capillary endothelium that regulate myocardial perfusion, is an increasingly recognized source of morbidity and mortality, particularly in the setting of metabolic syndrome. The coronary endothelium plays a pivotal role in maintaining homeostasis, though factors such as diabetes, hypertension, hyperlipidemia, and obesity can contribute to endothelial injury and consequently arteriolar vasomotor dysfunction. These disturbances in the coronary microvasculature clinically manifest as diminished coronary flow reserve, which is a known independent risk factor for cardiac death, even in the absence of macrovascular atherosclerotic disease. Therefore, a growing body of literature has examined the molecular mechanisms by which coronary microvascular injury occurs at the level of the endothelium and the consequences on arteriolar vasomotor responses. This review will begin with an overview of normal coronary microvascular physiology, modalities of measuring coronary microvascular function, and clinical implications of CMD. These introductory topics will be followed by a discussion of recent advances in the understanding of the mechanisms by which inflammation, oxidative stress, insulin resistance, hyperlipidemia, hypertension, shear stress, endothelial cell senescence, and tissue ischemia dysregulate coronary endothelial homeostasis and arteriolar vasomotor function.
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Affiliation(s)
- Sharif A Sabe
- Cardiovascular Research Center, Rhode Island Hospital, Providence, Rhode Island
- Division of Cardiothoracic Surgery, Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - Jun Feng
- Cardiovascular Research Center, Rhode Island Hospital, Providence, Rhode Island
- Division of Cardiothoracic Surgery, Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - Frank W Sellke
- Cardiovascular Research Center, Rhode Island Hospital, Providence, Rhode Island
- Division of Cardiothoracic Surgery, Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - M Ruhul Abid
- Cardiovascular Research Center, Rhode Island Hospital, Providence, Rhode Island
- Division of Cardiothoracic Surgery, Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
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16
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Sancho M, Fletcher J, Welsh DG. Inward Rectifier Potassium Channels: Membrane Lipid-Dependent Mechanosensitive Gates in Brain Vascular Cells. Front Cardiovasc Med 2022; 9:869481. [PMID: 35419431 PMCID: PMC8995785 DOI: 10.3389/fcvm.2022.869481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 02/28/2022] [Indexed: 11/13/2022] Open
Abstract
Cerebral arteries contain two primary and interacting cell types, smooth muscle (SMCs) and endothelial cells (ECs), which are each capable of sensing particular hemodynamic forces to set basal tone and brain perfusion. These biomechanical stimuli help confer tone within arterial networks upon which local neurovascular stimuli function. Tone development is intimately tied to arterial membrane potential (VM) and changes in intracellular [Ca2+] driven by voltage-gated Ca2+ channels (VGCCs). Arterial VM is in turn set by the dynamic interplay among ion channel species, the strongly inward rectifying K+ (Kir) channel being of special interest. Kir2 channels possess a unique biophysical signature in that they strongly rectify, display negative slope conductance, respond to elevated extracellular K+ and are blocked by micromolar Ba2+. While functional Kir2 channels are expressed in both smooth muscle and endothelium, they lack classic regulatory control, thus are often viewed as a simple background conductance. Recent literature has provided new insight, with two membrane lipids, phosphatidylinositol 4,5-bisphosphate (PIP2) and cholesterol, noted to (1) stabilize Kir2 channels in a preferred open or closed state, respectively, and (2) confer, in association with the cytoskeleton, caveolin-1 (Cav1) and syntrophin, hemodynamic sensitivity. It is these aspects of vascular Kir2 channels that will be the primary focus of this review.
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Affiliation(s)
- Maria Sancho
- Department of Pharmacology, University of Vermont, Burlington, VT, United States
- Department of Physiology, Faculty of Medicine, Universidad Complutense de Madrid, Madrid, Spain
- *Correspondence: Maria Sancho,
| | - Jacob Fletcher
- Department of Physiology and Pharmacology, Robarts Research Institute, University of Western Ontario, London, ON, Canada
| | - Donald G. Welsh
- Department of Physiology and Pharmacology, Robarts Research Institute, University of Western Ontario, London, ON, Canada
- Donald G. Welsh,
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17
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Ahn SJ, Le Master E, Lee JC, Phillips SA, Levitan I, Fancher IS. Differential effects of obesity on visceral versus subcutaneous adipose arteries: role of shear-activated Kir2.1 and alterations to the glycocalyx. Am J Physiol Heart Circ Physiol 2022; 322:H156-H166. [PMID: 34890278 PMCID: PMC8742723 DOI: 10.1152/ajpheart.00399.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Obesity imposes well-established deficits to endothelial function. We recently showed that obesity-induced endothelial dysfunction was mediated by disruption of the glycocalyx and a loss of Kir channel flow sensitivity. However, obesity-induced endothelial dysfunction is not observed in all vascular beds: visceral adipose arteries (VAAs), but not subcutaneous adipose arteries (SAAs), exhibit endothelial dysfunction. To determine whether differences in SAA versus VAA endothelial function observed in obesity are attributed to differential impairment of Kir channels and alterations to the glycocalyx, mice were fed a normal rodent diet, or a high-fat Western diet to induce obesity. Flow-induced vasodilation (FIV) was measured ex vivo. Functional downregulation of endothelial Kir2.1 was accomplished by transducing adipose arteries from mice and obese humans with adenovirus containing a dominant-negative Kir2.1 construct. Kir function was tested in freshly isolated endothelial cells seeded in a flow chamber for electrophysiological recordings under fluid shear. Atomic force microscopy was used to assess biophysical properties of the glycocalyx. Endothelial dysfunction was observed in VAAs of obese mice and humans. Downregulating Kir2.1 blunted FIV in SAAs, but had no effect on VAAs, from obese mice and humans. Obesity abolished Kir shear sensitivity in VAA endothelial cells and significantly altered the VAA glycocalyx. In contrast, Kir shear sensitivity was observed in SAA endothelial cells from obese mice and effects on SAA glycocalyx were less pronounced. We reveal distinct differences in Kir function and alterations to the glycocalyx that we propose contribute to the dichotomy in SAA versus VAA endothelial function with obesity.NEW & NOTEWORTHY We identified a role for endothelial Kir2.1 in the differences observed in VAA versus SAA endothelial function with obesity. The endothelial glycocalyx, a regulator of Kir activation by shear, is unequally perturbed in VAAs as compared with SAAs, which we propose results in a near complete loss of VAA endothelial Kir shear sensitivity and endothelial dysfunction. We propose that these differences underly the preserved endothelial function of SAA in obese mice and humans.
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Affiliation(s)
- Sang Joon Ahn
- 1Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Elizabeth Le Master
- 1Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - James C. Lee
- 2Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, Illinois
| | - Shane A. Phillips
- 3Department of Physical Therapy, College of Applied Health Sciences,
University of Illinois at Chicago, Chicago, Illinois
| | - Irena Levitan
- 1Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Ibra S. Fancher
- 4Department of Kinesiology and Applied Physiology, College of Health
Sciences, University of Delaware, Newark, Delaware
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18
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Ahn SJ, Fancher IS, Granados ST, Do Couto NF, Hwang CL, Phillips SA, Levitan I. Cholesterol-Induced Suppression of Endothelial Kir Channels Is a Driver of Impairment of Arteriolar Flow-Induced Vasodilation in Humans. Hypertension 2022; 79:126-138. [PMID: 34784737 PMCID: PMC8845492 DOI: 10.1161/hypertensionaha.121.17672] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Dyslipidemia-induced endothelial dysfunction is an important factor in the progression of cardiovascular disease; however, the underlying mechanisms are unclear. Our recent studies demonstrated that flow-induced vasodilation (FIV) is regulated by inwardly rectifying K+ channels (Kir2.1) in resistance arteries. Furthermore, we showed that hypercholesterolemia inhibits Kir2.1-dependent vasodilation. In this study, we introduced 2 new mouse models: (1) endothelial-specific deletion of Kir2.1 to demonstrate the role of endothelial Kir2.1 in FIV and (2) cholesterol-insensitive Kir2.1 mutant to determine the Kir2.1 regulation in FIV under hypercholesterolemia. FIV was significantly reduced in endothelial-specific Kir2.1 knock-out mouse mesenteric arteries compared with control groups. In cholesterol-insensitive Kir2.1 mutant mice, Kir2.1 currents were not affected by cyclodextrin and FIV was restored in cells and arteries, respectively, with a hypercholesterolemic background. To extend our observations to humans, 16 healthy subjects were recruited with LDL (low-density lipoprotein)-cholesterol ranging from 51 to 153 mg/dL and FIV was assessed in resistance arteries isolated from gluteal adipose. Resistance arteries from participants with >100 mg/dL LDL (high-LDL) exhibited reduced FIV as compared with those participants with <100 mg/dL LDL (low-LDL). A significant negative correlation was observed between LDL cholesterol and FIV in high-LDL. Expressing dominant-negative Kir2.1 in endothelium blunted FIV in arteries from low-LDL but had no further effect on FIV in arteries from high-LDL. The Kir2.1-dependent vasodilation more negatively correlated to LDL cholesterol in high-LDL. Overexpressing wild-type Kir2.1 in endothelium fully recovered FIV in arteries from participants with high-LDL. Our data suggest that cholesterol-induced suppression of Kir2.1 is a major mechanism underlying endothelial dysfunction in hypercholesterolemia.
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Affiliation(s)
- Sang Joon Ahn
- Department of Medicine, Division of Pulmonary, Critical Care, Allergy and Sleep, College of Medicine, University of Illinois at Chicago
| | - Ibra S. Fancher
- Department of Medicine, Division of Pulmonary, Critical Care, Allergy and Sleep, College of Medicine, University of Illinois at Chicago,Department of Kinesiology and Applied Physiology, University of Delaware
| | - Sara T. Granados
- Department of Medicine, Division of Pulmonary, Critical Care, Allergy and Sleep, College of Medicine, University of Illinois at Chicago
| | - Natalia F. Do Couto
- Department of Medicine, Division of Pulmonary, Critical Care, Allergy and Sleep, College of Medicine, University of Illinois at Chicago,Department of Physical Therapy, College of Applied Health Science, University of Illinois at Chicago
| | - Chueh-Lung Hwang
- Department of Physical Therapy, College of Applied Health Science, University of Illinois at Chicago
| | - Shane A. Phillips
- Department of Physical Therapy, College of Applied Health Science, University of Illinois at Chicago
| | - Irena Levitan
- Department of Medicine, Division of Pulmonary, Critical Care, Allergy and Sleep, College of Medicine, University of Illinois at Chicago
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19
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Hakim MA, Behringer EJ. Methyl-Beta-Cyclodextrin Restores K IR Channel Function in Brain Endothelium of Female Alzheimer's Disease Mice. J Alzheimers Dis Rep 2021; 5:693-703. [PMID: 34755043 PMCID: PMC8543374 DOI: 10.3233/adr-210016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2021] [Indexed: 12/12/2022] Open
Abstract
Background: As the sixth-leading cause of death in the United States, Alzheimer’s disease (AD) entails deteriorating endothelial control of blood flow throughout the brain. In particular, reduced inward-rectifying K+ (KIR) channel function in animal models of aging and AD compromises endothelial function and optimal perfusion of brain parenchyma. Deficient endothelial KIR channels may result from aberrant interaction with plasma membrane cholesterol as a primary regulator of membrane fluidity and ion channels. Objective: We tested the hypothesis that mild methyl-β-cyclodextrin (MβCD) treatment to reduce membrane cholesterol may restore endothelial KIR channel function in brain endothelium of old AD mice. Methods: Membrane potential was continuously measured in isolated endothelial tubes from posterior cerebral arteries of young (1 to 3 months) and old (16 to 19 months) female 3xTg-AD mice before and after mild treatment with the cholesterol-removing agent MβCD (1 mmol/L). Elevated extracellular potassium ([K+]E; 15 mmol/L) and NS309 (1μmol/L) activated KIR and Ca2+-activated K+ (SKCa/IKCa) channels respectively before and after MβCD treatment. Results: SKCa/IKCa channel function for producing hyperpolarization remained stable regardless of age group and MβCD treatment (ΔVm: ∼–33 mV). However, as deficient during AD, KIR channel function was restored (ΔVm: –9±1 mV) versus pre-MβCD conditions (–5±1 mV); a progressive effect that reached –14±1 mV hyperpolarization at 60 min following MβCD washout. Conclusion: In female animals, MβCD treatment of brain endothelium selectively restores KIR versus SKCa/IKCa channel function during AD. Thus, the endothelial cholesterol-KIR channel interface is a novel target for ameliorating perfusion of the AD brain.
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Affiliation(s)
- Md A Hakim
- Basic Sciences, Loma Linda University, Loma Linda, CA, USA
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20
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Fancher IS. Cardiovascular mechanosensitive ion channels-Translating physical forces into physiological responses. CURRENT TOPICS IN MEMBRANES 2021; 87:47-95. [PMID: 34696889 DOI: 10.1016/bs.ctm.2021.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cells and tissues are constantly exposed to mechanical stress. In order to respond to alterations in mechanical stimuli, specific cellular machinery must be in place to rapidly convert physical force into chemical signaling to achieve the desired physiological responses. Mechanosensitive ion channels respond to such physical stimuli in the order of microseconds and are therefore essential components to mechanotransduction. Our understanding of how these ion channels contribute to cellular and physiological responses to mechanical force has vastly expanded in the last few decades due to engineering ingenuities accompanying patch clamp electrophysiology, as well as sophisticated molecular and genetic approaches. Such investigations have unveiled major implications for mechanosensitive ion channels in cardiovascular health and disease. Therefore, in this chapter I focus on our present understanding of how biophysical activation of various mechanosensitive ion channels promotes distinct cell signaling events with tissue-specific physiological responses in the cardiovascular system. Specifically, I discuss the roles of mechanosensitive ion channels in mediating (i) endothelial and smooth muscle cell control of vascular tone, (ii) mechano-electric feedback and cell signaling pathways in cardiomyocytes and cardiac fibroblasts, and (iii) the baroreflex.
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Affiliation(s)
- Ibra S Fancher
- Department of Kinesiology and Applied Physiology, College of Health Sciences, University of Delaware, Newark, DE, United States.
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21
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Hakim MA, Behringer EJ. Development of Alzheimer's Disease Progressively Alters Sex-Dependent KCa and Sex-Independent KIR Channel Function in Cerebrovascular Endothelium. J Alzheimers Dis 2021; 76:1423-1442. [PMID: 32651315 DOI: 10.3233/jad-200085] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Development of Alzheimer's disease (AD) pathology is associated with impaired blood flow delivery of oxygen and nutrients throughout the brain. Cerebrovascular endothelium regulates vasoreactivity of blood vessel networks for optimal cerebral blood flow. OBJECTIVE We tested the hypothesis that cerebrovascular endothelial Gq-protein-coupled receptor (GPCR; purinergic and muscarinic) and K+ channel [Ca2+-activated (KCa2.3/SK3 and KCa3.1/IK1) and inward-rectifying (KIR2.x)] function declines during progressive AD pathology. METHODS We applied simultaneous measurements of intracellular Ca2+ ([Ca2+]i) and membrane potential (Vm) in freshly isolated endothelium from posterior cerebral arteries of 3×Tg-AD mice [young, no pathology (1- 2 mo), cognitive impairment (CI; 4- 5 mo), extracellular Aβ plaques (Aβ; 6- 8 mo), and Aβ plaques + neurofibrillary tangles (AβT; 12- 15 mo)]. RESULTS The coupling of ΔVm-to-Δ[Ca2+]i during AβT pathology was lowest for both sexes but, overall, ATP-induced purinergic receptor function was stable throughout AD pathology. SKCa/IKCa channel function itself was enhanced by ∼20% during AD (Aβ+ AβT) versus pre-AD (Young + CI) in males while steady in females. Accordingly, hyperpolarization-induced [Ca2+]i increases following SKCa/IKCa channel activation and Δ[Ca2+]i-to-ΔVm coupling was enhanced by ≥two-fold during AD pathology in males but not females. Further, KIR channel function decreased by ∼50% during AD conditions versus young regardless of sex. Finally, other than a ∼40% increase in females versus males during Aβ pathology, [Ca2+]i responses to the mitochondrial uncoupler FCCP were similar among AD versus pre-AD conditions. CONCLUSION Altogether, AD pathology represents a condition of altered KCa and KIR channel function in cerebrovascular endothelium in a sex-dependent and sex-independent manner respectively.
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Affiliation(s)
- Md A Hakim
- Basic Sciences, Loma Linda University, Loma Linda, CA, USA
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22
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Marlow B, Kuenze G, Li B, Sanders CR, Meiler J. Structural determinants of cholesterol recognition in helical integral membrane proteins. Biophys J 2021; 120:1592-1604. [PMID: 33640379 DOI: 10.1016/j.bpj.2021.02.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 01/12/2021] [Accepted: 02/08/2021] [Indexed: 12/20/2022] Open
Abstract
Cholesterol is an integral component of mammalian membranes. It has been shown to modulate membrane fluidity and dynamics and alter integral membrane protein function. However, understanding the molecular mechanisms of how cholesterol impacts protein function is complicated by limited and conflicting structural data. Because of the nature of the crystallization and cryo-EM structure determination, it is difficult to distinguish between specific and biologically relevant interactions and a nonspecific association. The only widely recognized search algorithm for cholesterol-integral-membrane-protein interaction sites is sequence based, i.e., searching for the so-called "Cholesterol Recognition/interaction Amino acid Consensus" motif. Although these motifs are present in numerous integral membrane proteins, there is inconclusive evidence to support their necessity or sufficiency for cholesterol binding. Here, we leverage the increasing number of experimental cholesterol-integral-membrane-protein structures to systematically analyze putative interaction sites based on their spatial arrangement and evolutionary conservation. This analysis creates three-dimensional representations of general cholesterol interaction sites that form clusters across multiple integral membrane protein classes. We also classify cholesterol-integral-membrane-protein interaction sites as either likely-specific or nonspecific. Information gleaned from our characterization will eventually enable a structure-based approach to predict and design cholesterol-integral-membrane-protein interaction sites.
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Affiliation(s)
- Brennica Marlow
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Chemical and Physical Biology Program, Vanderbilt University, Nashville, Tennessee
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee; Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - Bian Li
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee
| | - Charles R Sanders
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Biochemistry, Vanderbilt University, Nashville, Tennessee
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Chemical and Physical Biology Program, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee; Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany.
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23
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Fancher IS, Le Master E, Ahn SJ, Adamos C, Lee JC, Berdyshev E, Dull RO, Phillips SA, Levitan I. Impairment of Flow-Sensitive Inwardly Rectifying K + Channels via Disruption of Glycocalyx Mediates Obesity-Induced Endothelial Dysfunction. Arterioscler Thromb Vasc Biol 2020; 40:e240-e255. [PMID: 32698687 DOI: 10.1161/atvbaha.120.314935] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE To determine if endothelial dysfunction in a mouse model of diet-induced obesity and in obese humans is mediated by the suppression of endothelial Kir (inwardly rectifying K+) channels. Approach and Results: Endothelial dysfunction, observed as reduced dilations to flow, occurred after feeding mice a high-fat, Western diet for 8 weeks. The functional downregulation of endothelial Kir2.1 using dominant-negative Kir2.1 construct resulted in substantial reductions in the response to flow in mesenteric arteries of lean mice, whereas no effect was observed in arteries of obese mice. Overexpressing wild-type-Kir2.1 in endothelium of arteries from obese mice resulted in full recovery of the flow response. Exposing freshly isolated endothelial cells to fluid shear during patch-clamp electrophysiology revealed that the flow-sensitivity of Kir was virtually abolished in cells from obese mice. Atomic force microscopy revealed that the endothelial glycocalyx was stiffer and the thickness of the glycocalyx layer reduced in arteries from obese mice. We also identified that the length of the glycocalyx is critical to the flow-activation of Kir. Overexpressing Kir2.1 in endothelium of arteries from obese mice restored flow- and heparanase-sensitivity, indicating an important role for heparan sulfates in the flow-activation of Kir. Furthermore, the Kir2.1-dependent component of flow-induced vasodilation was lost in the endothelium of resistance arteries of obese humans obtained from biopsies collected during bariatric surgery. CONCLUSIONS We conclude that obesity-induced impairment of flow-induced vasodilation is attributed to the loss of flow-sensitivity of endothelial Kir channels and propose that the latter is mediated by the biophysical alterations of the glycocalyx.
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Affiliation(s)
- Ibra S Fancher
- From the Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine (I.S.F., E.L.M., S.J.A., C.A., I.L.), University of Illinois at Chicago
| | - Elizabeth Le Master
- From the Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine (I.S.F., E.L.M., S.J.A., C.A., I.L.), University of Illinois at Chicago
| | - Sang Joon Ahn
- From the Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine (I.S.F., E.L.M., S.J.A., C.A., I.L.), University of Illinois at Chicago
| | - Crystal Adamos
- From the Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine (I.S.F., E.L.M., S.J.A., C.A., I.L.), University of Illinois at Chicago
| | - James C Lee
- Departement of Bioengineering (J.C.L.), University of Illinois at Chicago
| | - Evgeny Berdyshev
- Division of Pulmonary, Critical Care and Sleep Medicine, Departement of Medicine, National Jewish Health, Denver, CO (E.B.)
| | - Randal O Dull
- Department of Anesthesiology, University of Arizona College of Medicine, Banner-University Medical Center, Tucson (R.O.D.)
| | - Shane A Phillips
- Department of Physical Therapy (S.A.P.), University of Illinois at Chicago
| | - Irena Levitan
- From the Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine (I.S.F., E.L.M., S.J.A., C.A., I.L.), University of Illinois at Chicago
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24
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Sancho M, Welsh DG. K IR channels in the microvasculature: Regulatory properties and the lipid-hemodynamic environment. CURRENT TOPICS IN MEMBRANES 2020; 85:227-259. [PMID: 32402641 DOI: 10.1016/bs.ctm.2020.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Basal tone and perfusion control is set in cerebral arteries by the sensing of pressure and flow, key hemodynamic stimuli. These forces establish a contractile foundation within arterial networks upon which local neurovascular stimuli operate. This fundamental process is intimately tied to arterial VM and the rise in cytosolic [Ca2+] by the graded opening of voltage-operated Ca2+ channels. Arterial VM is in turn controlled by a dynamic interaction among several resident ion channels, KIR being one of particular significance. As the name suggests, KIR displays strong inward rectification, retains a small outward component, potentiated by extracellular K+ and blocked by micromolar Ba2+. Cerebrovascular KIR is unique from other K+ currents as it is present in both smooth muscle and endothelium yet lacking in classical regulatory modulation. Such observations have fostered the view that KIR is nothing more than a background conductance, activated by extracellular K+ and which passively facilitates dilation. Recent work in cell model systems has; however, identified two membrane lipids, phosphatidylinositol 4,5-bisphosphate (PIP2) and cholesterol, that interact with KIR2.x, to stabilize the channel in the preferred open or silent state, respectively. Translating this unique form of regulation, recent studies have demonstrated that specific lipid-protein interactions enable unique KIR populations to sense distinct hemodynamic stimuli and set basal tone. This review summarizes the current knowledge of vascular KIR channels and how the lipid and hemodynamic impact their activity.
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Affiliation(s)
- Maria Sancho
- Robarts Research Institute and the Department of Physiology & Pharmacology, University of Western Ontario, London, ON, Canada
| | - Donald G Welsh
- Robarts Research Institute and the Department of Physiology & Pharmacology, University of Western Ontario, London, ON, Canada.
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25
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Fancher IS, Levitan I. Endothelial inwardly-rectifying K + channels as a key component of shear stress-induced mechanotransduction. CURRENT TOPICS IN MEMBRANES 2020; 85:59-88. [PMID: 32402645 DOI: 10.1016/bs.ctm.2020.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
It has been recognized for decades that fluid shear stress plays a major role in vascular function. Acting on the endothelium shear stress induces vasorelaxation of resistance arteries and plays a major role in the propensity of the major arteries to atherosclerosis. Many elements of shear-induced signaling have been identified yet we are just beginning to decipher the roles that mechanosensitive ion channels may play in the signaling pathways initiated by shear stress. Endothelial inwardly-rectifying K+ channels were identified as potential primary mechanosensors in the late 1980s yet until our recent works, highlighted in the forthcoming chapter, the functional effect of a shear-activated K+ current was completely unknown. In this chapter, we present the physiological effects of shear stress in arteries in health and disease and highlight the most prevalent of today's investigated mechanosensitive ion channels. Ultimately, we focus on Kir2.1 channels and discuss in detail our findings regarding the downstream signaling events that are induced by shear-activated endothelial Kir2.1 channels. Most importantly, we examine our findings regarding hypercholesterolemia-induced inhibition of Kir channel shear-sensitivity and the impact on endothelial function in the context of flow (shear)-mediated vasodilation and atherosclerosis.
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Affiliation(s)
- Ibra S Fancher
- Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, IL, United States.
| | - Irena Levitan
- Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, IL, United States
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26
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Xu F, Liu Y, Zhu X, Li S, Shi X, Li Z, Ai M, Sun J, Hou B, Cai W, Sun H, Ni L, Zhou Y, Qiu L. Protective Effects and Mechanisms of Vaccarin on Vascular Endothelial Dysfunction in Diabetic Angiopathy. Int J Mol Sci 2019; 20:ijms20184587. [PMID: 31533227 PMCID: PMC6769517 DOI: 10.3390/ijms20184587] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 08/29/2019] [Accepted: 09/09/2019] [Indexed: 12/11/2022] Open
Abstract
Cardiovascular complications are a major leading cause of mortality in patients suffering from type 2 diabetes mellitus (T2DM). Vascular endothelial dysfunction is a core pathophysiological event in the early stage of T2DM and eventually leads to cardiovascular disease. Vaccarin (VAC), an active flavonoid glycoside extracted from vaccariae semen, exhibits extensive biological activities including vascular endothelial cell protection effects. However, little is known about whether VAC is involved in endothelial dysfunction regulation under high glucose (HG) or hyperglycemia conditions. Here, in an in vivo study, we found that VAC attenuated increased blood glucose, increased glucose and insulin tolerance, relieved the disorder of lipid metabolism and oxidative stress, and improved endothelium-dependent vasorelaxation in STZ/HFD-induced T2DM mice. Furthermore, in cultured human microvascular endothelial cell-1 (HMEC-1) cells, we showed that pretreatment with VAC dose-dependently increased nitric oxide (NO) generation and the phosphorylation of eNOS under HG conditions. Mechanistically, VAC-treated HMEC-1 cells exhibited higher AMPK phosphorylation, which was attenuated by HG stimulation. Moreover, HG-triggered miRNA-34a upregulation was inhibited by VAC pretreatment, which is in accordance with pretreatment with AMPK inhibitor compound C (CC). In addition, both reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC) and VAC abolished HG-evoked dephosphorylation of AMPK and eNOS, increased miRNA-34a expression, and decreased NO production. These results suggest that VAC impedes HG-induced endothelial dysfunction via inhibition of the ROS/AMPK/miRNA-34a/eNOS signaling cascade.
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Affiliation(s)
- Fei Xu
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Yixiao Liu
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Xuexue Zhu
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Shuangshuang Li
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Xuelin Shi
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Zhongjie Li
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Min Ai
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Jiangnan Sun
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Bao Hou
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Weiwei Cai
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Haijian Sun
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Lulu Ni
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Yuetao Zhou
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
| | - Liying Qiu
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214100, China.
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27
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Alaaeddine R, Elkhatib MAW, Mroueh A, Fouad H, Saad EI, El-Sabban ME, Plane F, El-Yazbi AF. Impaired Endothelium-Dependent Hyperpolarization Underlies Endothelial Dysfunction during Early Metabolic Challenge: Increased ROS Generation and Possible Interference with NO Function. J Pharmacol Exp Ther 2019; 371:567-582. [PMID: 31511364 DOI: 10.1124/jpet.119.262048] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Accepted: 09/06/2019] [Indexed: 12/18/2022] Open
Abstract
Endothelial dysfunction is a hallmark of diabetic vasculopathies. Although hyperglycemia is believed to be the culprit causing endothelial damage, the mechanism underlying early endothelial insult in prediabetes remains obscure. We used a nonobese high-calorie (HC)-fed rat model with hyperinsulinemia, hypercholesterolemia, and delayed development of hyperglycemia to unravel this mechanism. Compared with aortic rings from control rats, HC-fed rat rings displayed attenuated acetylcholine-mediated relaxation. While sensitive to nitric oxide synthase (NOS) inhibition, aortic relaxation in HC-rat tissues was not affected by blocking the inward-rectifier potassium (Kir) channels using BaCl2 Although Kir channel expression was reduced in HC-rat aorta, Kir expression, endothelium-dependent relaxation, and the BaCl2-sensitive component improved in HC rats treated with atorvastatin to reduce serum cholesterol. Remarkably, HC tissues demonstrated increased reactive species (ROS) in smooth muscle cells, which was reversed in rats receiving atorvastatin. In vitro ROS reduction, with superoxide dismutase, improved endothelium-dependent relaxation in HC-rat tissues. Significantly, connexin-43 expression increased in HC aortic tissues, possibly allowing ROS movement into the endothelium and reduction of eNOS activity. In this context, gap junction blockade with 18-β-glycyrrhetinic acid reduced vascular tone in HC rat tissues but not in controls. This reduction was sensitive to NOS inhibition and SOD treatment, possibly as an outcome of reduced ROS influence, and emerged in BaCl2-treated control tissues. In conclusion, our results suggest that early metabolic challenge leads to reduced Kir-mediated endothelium-dependent hyperpolarization, increased vascular ROS potentially impairing NO synthesis and highlight these channels as a possible target for early intervention with vascular dysfunction in metabolic disease. SIGNIFICANCE STATEMENT: The present study examines early endothelial dysfunction in metabolic disease. Our results suggest that reduced inward-rectifier potassium channel function underlies a defective endothelium-mediated relaxation possibly through alteration of nitric oxide synthase activity. This study provides a possible mechanism for the augmentation of relatively small changes in one endothelium-mediated relaxation pathway to affect overall endothelial response and highlights the potential role of inward-rectifier potassium channel function as a therapeutic target to treat vascular dysfunction early in the course of metabolic disease.
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Affiliation(s)
- Rana Alaaeddine
- Departments of Pharmacology and Therapeutics (R.A., A.M., A.F.E.-Y.) and Anatomy, Cell Biology, and Physiology (M.E.E.-S.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt (M.A.W.E., H.F., E.I.S., A.F.E.-Y.); and Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada (F.P.)
| | - Mohammed A W Elkhatib
- Departments of Pharmacology and Therapeutics (R.A., A.M., A.F.E.-Y.) and Anatomy, Cell Biology, and Physiology (M.E.E.-S.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt (M.A.W.E., H.F., E.I.S., A.F.E.-Y.); and Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada (F.P.)
| | - Ali Mroueh
- Departments of Pharmacology and Therapeutics (R.A., A.M., A.F.E.-Y.) and Anatomy, Cell Biology, and Physiology (M.E.E.-S.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt (M.A.W.E., H.F., E.I.S., A.F.E.-Y.); and Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada (F.P.)
| | - Hosny Fouad
- Departments of Pharmacology and Therapeutics (R.A., A.M., A.F.E.-Y.) and Anatomy, Cell Biology, and Physiology (M.E.E.-S.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt (M.A.W.E., H.F., E.I.S., A.F.E.-Y.); and Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada (F.P.)
| | - Evan I Saad
- Departments of Pharmacology and Therapeutics (R.A., A.M., A.F.E.-Y.) and Anatomy, Cell Biology, and Physiology (M.E.E.-S.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt (M.A.W.E., H.F., E.I.S., A.F.E.-Y.); and Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada (F.P.)
| | - Marwan E El-Sabban
- Departments of Pharmacology and Therapeutics (R.A., A.M., A.F.E.-Y.) and Anatomy, Cell Biology, and Physiology (M.E.E.-S.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt (M.A.W.E., H.F., E.I.S., A.F.E.-Y.); and Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada (F.P.)
| | - Frances Plane
- Departments of Pharmacology and Therapeutics (R.A., A.M., A.F.E.-Y.) and Anatomy, Cell Biology, and Physiology (M.E.E.-S.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt (M.A.W.E., H.F., E.I.S., A.F.E.-Y.); and Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada (F.P.)
| | - Ahmed F El-Yazbi
- Departments of Pharmacology and Therapeutics (R.A., A.M., A.F.E.-Y.) and Anatomy, Cell Biology, and Physiology (M.E.E.-S.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt (M.A.W.E., H.F., E.I.S., A.F.E.-Y.); and Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada (F.P.)
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28
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Endothelium-Dependent Hyperpolarization (EDH) in Diabetes: Mechanistic Insights and Therapeutic Implications. Int J Mol Sci 2019; 20:ijms20153737. [PMID: 31370156 PMCID: PMC6695796 DOI: 10.3390/ijms20153737] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 07/25/2019] [Accepted: 07/30/2019] [Indexed: 02/07/2023] Open
Abstract
Diabetes mellitus is one of the major risk factors for cardiovascular disease and is an important health issue worldwide. Long-term diabetes causes endothelial dysfunction, which in turn leads to diabetic vascular complications. Endothelium-derived nitric oxide is a major vasodilator in large-size vessels, and the hyperpolarization of vascular smooth muscle cells mediated by the endothelium plays a central role in agonist-mediated and flow-mediated vasodilation in resistance-size vessels. Although the mechanisms underlying diabetic vascular complications are multifactorial and complex, impairment of endothelium-dependent hyperpolarization (EDH) of vascular smooth muscle cells would contribute at least partly to the initiation and progression of microvascular complications of diabetes. In this review, we present the current knowledge about the pathophysiology and underlying mechanisms of impaired EDH in diabetes in animals and humans. We also discuss potential therapeutic approaches aimed at the prevention and restoration of EDH in diabetes.
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Boriushkin E, Fancher IS, Levitan I. Shear-Stress Sensitive Inwardly-Rectifying K + Channels Regulate Developmental Retinal Angiogenesis by Vessel Regression. Cell Physiol Biochem 2019; 52:1569-1583. [PMID: 31145841 PMCID: PMC7063968 DOI: 10.33594/000000109] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/27/2019] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND/AIMS Shear stress plays major roles in developmental angiogenesis, particularly in blood vessel remodeling and maturation but little is known about the shear stress sensors involved in this process. Our recent study identified endothelial Kir2.1 channels as major contributors to flow-induced vasodilation, a hallmark of the endothelial flow response. The goal of this study is to establish the role of Kir2.1 in the regulation of retinal angiogenesis. METHODS The retina of newly born Kir2.1+/- mice were used to investigate the sprouting angiogenesis and remodeling of newly formed branched vessels. The structure, blood density and mural cell coverage have been evaluated by immunohistochemistry of the whole-mount retina. Endothelial cell alignment was assessed using CD31 staining. The experiments with flow-induced vasodilation were used to study the cerebrovascular response to flow. RESULTS Using Kir2.1-deficient mice, we show that the retinas of Kir2.1+/- mice have higher vessel density, increased lengths and increased number of the branching points, as compared to WT littermates. In contrast, the coverage by αSMA is decreased in Kir2.1+/- mice while pericyte coverage does not change. Furthermore, to determine whether deficiency of Kir2.1 affects vessel pruning, we discriminated between intact and degraded vessels or "empty matrix sleeves" and found a significant reduction in the number of empty sleeves on the peripheral part of the retina or "angiogenic front" in Kir2.1+/- mice. We also show that Kir2.1 deficiency results in decreased endothelial alignment in retinal endothelium and impaired flow-induced vasodilation of cerebral arteries, verifying the involvement of Kir2.1 in shear-stress sensing in retina and cerebral circulation. CONCLUSION This study shows that shear-stress sensitive Kir2.1 channels play an important role in pruning of excess vessels and vascular remodeling during retinal angiogenesis. We propose that Kir2.1 mediates the effect of shear stress on vessel maturation.
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Affiliation(s)
| | - Ibra S Fancher
- Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Irena Levitan
- Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, IL, USA
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30
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Sancho M, Fabris S, Hald BO, Brett SE, Sandow SL, Poepping TL, Welsh DG. Membrane Lipid-K
IR
2.x Channel Interactions Enable Hemodynamic Sensing in Cerebral Arteries. Arterioscler Thromb Vasc Biol 2019; 39:1072-1087. [DOI: 10.1161/atvbaha.119.312493] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Objective—
Inward rectifying K
+
(K
IR
) channels are present in cerebral arterial smooth muscle and endothelial cells, a tandem arrangement suggestive of a dynamic yet undiscovered role for this channel. This study defined whether distinct pools of cerebral arterial K
IR
channels were uniquely modulated by membrane lipids and hemodynamic stimuli.
Approach and Results—
A Ba
2+
-sensitive K
IR
current was isolated in smooth muscle and endothelial cells of rat cerebral arteries; molecular analyses subsequently confirmed K
IR
2.1/K
IR
2.2 mRNA and protein expression in both cells. Patch-clamp electrophysiology next demonstrated that each population of K
IR
channels was sensitive to key membrane lipids and hemodynamic stimuli. In this regard, endothelial K
IR
was sensitive to phosphatidylinositol 4,5-bisphosphate content, with depletion impairing the ability of laminar shear stress to activate this channel pool. In contrast, smooth muscle K
IR
was sensitive to membrane cholesterol content, with sequestration blocking the ability of pressure to inhibit channel activity. The idea that membrane lipids help confer shear stress and pressure sensitivity of K
IR
channels was confirmed in intact arteries using myography. Virtual models integrating structural/electrical observations reconceptualized K
IR
as a dynamic regulator of membrane potential working in concert with other currents to set basal tone across a range of shear stresses and intravascular pressures.
Conclusions—
The data show for the first time that specific membrane lipid-K
IR
interactions enable unique channel populations to sense hemodynamic stimuli and drive vasomotor responses to set basal perfusion in the cerebral circulation.
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Affiliation(s)
- Maria Sancho
- From the Department of Physiology and Pharmacology, Robarts Research Institute (M.S., S.F., S.E.B., D.G.W.), University of Western Ontario, London, Canada
| | - Sergio Fabris
- From the Department of Physiology and Pharmacology, Robarts Research Institute (M.S., S.F., S.E.B., D.G.W.), University of Western Ontario, London, Canada
| | - Bjorn O. Hald
- Department of Neuroscience, Translational Neurobiology, University of Copenhagen, Denmark (B.O.H.)
| | - Suzanne E. Brett
- From the Department of Physiology and Pharmacology, Robarts Research Institute (M.S., S.F., S.E.B., D.G.W.), University of Western Ontario, London, Canada
| | - Shaun L. Sandow
- Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Queensland, Australia (S.L.S.)
| | - Tamie L. Poepping
- Department of Physics and Astronomy (T.L.P.), University of Western Ontario, London, Canada
| | - Donald G. Welsh
- From the Department of Physiology and Pharmacology, Robarts Research Institute (M.S., S.F., S.E.B., D.G.W.), University of Western Ontario, London, Canada
- Department of Physiology and Pharmacology, University of Calgary, Alberta, Canada (D.G.W.)
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31
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Fang Y, Wu D, Birukov KG. Mechanosensing and Mechanoregulation of Endothelial Cell Functions. Compr Physiol 2019; 9:873-904. [PMID: 30873580 PMCID: PMC6697421 DOI: 10.1002/cphy.c180020] [Citation(s) in RCA: 107] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Vascular endothelial cells (ECs) form a semiselective barrier for macromolecules and cell elements regulated by dynamic interactions between cytoskeletal elements and cell adhesion complexes. ECs also participate in many other vital processes including innate immune reactions, vascular repair, secretion, and metabolism of bioactive molecules. Moreover, vascular ECs represent a unique cell type exposed to continuous, time-dependent mechanical forces: different patterns of shear stress imposed by blood flow in macrovasculature and by rolling blood cells in the microvasculature; circumferential cyclic stretch experienced by the arterial vascular bed caused by heart propulsions; mechanical stretch of lung microvascular endothelium at different magnitudes due to spontaneous respiration or mechanical ventilation in critically ill patients. Accumulating evidence suggests that vascular ECs contain mechanosensory complexes, which rapidly react to changes in mechanical loading, process the signal, and develop context-specific adaptive responses to rebalance the cell homeostatic state. The significance of the interactions between specific mechanical forces in the EC microenvironment together with circulating bioactive molecules in the progression and resolution of vascular pathologies including vascular injury, atherosclerosis, pulmonary edema, and acute respiratory distress syndrome has been only recently recognized. This review will summarize the current understanding of EC mechanosensory mechanisms, modulation of EC responses to humoral factors by surrounding mechanical forces (particularly the cyclic stretch), and discuss recent findings of magnitude-specific regulation of EC functions by transcriptional, posttranscriptional and epigenetic mechanisms using -omics approaches. We also discuss ongoing challenges and future opportunities in developing new therapies targeting dysregulated mechanosensing mechanisms to treat vascular diseases. © 2019 American Physiological Society. Compr Physiol 9:873-904, 2019.
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Affiliation(s)
- Yun Fang
- Department of Medicine, University of Chicago, Chicago, Illinois, USA,Correspondence to
| | - David Wu
- Department of Medicine, University of Chicago, Chicago, Illinois, USA
| | - Konstantin G. Birukov
- Department of Anesthesiology, University of Maryland Baltimore School of Medicine, Baltimore, Maryland, USA
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32
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Barbera N, Levitan I. Chiral Specificity of Cholesterol Orientation Within Cholesterol Binding Sites in Inwardly Rectifying K+ Channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1115:77-95. [DOI: 10.1007/978-3-030-04278-3_4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Affiliation(s)
- Nhat-Tu Le
- Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX
| | - Jun-Ichi Abe
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX
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