1
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Manning D, Rivera EJ, Santana LF. The life cycle of a capillary: Mechanisms of angiogenesis and rarefaction in microvascular physiology and pathologies. Vascul Pharmacol 2024; 156:107393. [PMID: 38857638 DOI: 10.1016/j.vph.2024.107393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 06/02/2024] [Accepted: 06/07/2024] [Indexed: 06/12/2024]
Abstract
Capillaries are the smallest blood vessels (<10 μm in diameter) in the body and their walls are lined by endothelial cells. These microvessels play a crucial role in nutrient and gas exchange between blood and tissues. Capillary endothelial cells also produce vasoactive molecules and initiate the electrical signals that underlie functional hyperemia and neurovascular coupling. Accordingly, capillary function and density are critical for all cell types to match blood flow to cellular activity. This begins with the process of angiogenesis, when new capillary blood vessels emerge from pre-existing vessels, and ends with rarefaction, the loss of these microvascular structures. This review explores the mechanisms behind these processes, emphasizing their roles in various microvascular diseases and their impact on surrounding cells in health and disease. We discuss recent work on the mechanisms controlling endothelial cell proliferation, migration, and tube formation that underlie angiogenesis under physiological and pathological conditions. The mechanisms underlying functional and anatomical rarefaction and the role of pericytes in this process are also discussed. Based on this work, a model is proposed in which the balance of angiogenic and rarefaction signaling pathways in a particular tissue match microvascular density to the metabolic demands of the surrounding cells. This negative feedback loop becomes disrupted during microvascular rarefaction: angiogenic mechanisms are blunted, reactive oxygen species accumulate, capillary function declines and eventually, capillaries disappear. This, we propose, forms the foundation of the reciprocal relationship between vascular density, blood flow, and metabolic needs and functionality of nearby cells.
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Affiliation(s)
- Declan Manning
- Department of Physiology & Membrane Biology, School of Medicine, University of California, Davis, United States of America.
| | - Ernesto J Rivera
- Department of Physiology & Membrane Biology, School of Medicine, University of California, Davis, United States of America
| | - L Fernando Santana
- Department of Physiology & Membrane Biology, School of Medicine, University of California, Davis, United States of America
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2
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Lim XR, Harraz OF. Mechanosensing by Vascular Endothelium. Annu Rev Physiol 2024; 86:71-97. [PMID: 37863105 PMCID: PMC10922104 DOI: 10.1146/annurev-physiol-042022-030946] [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] [Indexed: 10/22/2023]
Abstract
Mechanical forces influence different cell types in our bodies. Among the earliest forces experienced in mammals is blood movement in the vascular system. Blood flow starts at the embryonic stage and ceases when the heart stops. Blood flow exposes endothelial cells (ECs) that line all blood vessels to hemodynamic forces. ECs detect these mechanical forces (mechanosensing) through mechanosensors, thus triggering physiological responses such as changes in vascular diameter. In this review, we focus on endothelial mechanosensing and on how different ion channels, receptors, and membrane structures detect forces and mediate intricate mechanotransduction responses. We further highlight that these responses often reflect collaborative efforts involving several mechanosensors and mechanotransducers. We close with a consideration of current knowledge regarding the dysregulation of endothelial mechanosensing during disease. Because hemodynamic disruptions are hallmarks of cardiovascular disease, studying endothelial mechanosensing holds great promise for advancing our understanding of vascular physiology and pathophysiology.
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Affiliation(s)
- Xin Rui Lim
- Department of Pharmacology, Larner College of Medicine and Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, Vermont, USA;
| | - Osama F Harraz
- Department of Pharmacology, Larner College of Medicine and Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, Vermont, USA;
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3
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Longden TA, Lederer WJ. Electro-metabolic signaling. J Gen Physiol 2024; 156:e202313451. [PMID: 38197953 PMCID: PMC10783436 DOI: 10.1085/jgp.202313451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/27/2023] [Accepted: 12/14/2023] [Indexed: 01/11/2024] Open
Abstract
Precise matching of energy substrate delivery to local metabolic needs is essential for the health and function of all tissues. Here, we outline a mechanistic framework for understanding this critical process, which we refer to as electro-metabolic signaling (EMS). All tissues exhibit changes in metabolism over varying spatiotemporal scales and have widely varying energetic needs and reserves. We propose that across tissues, common signatures of elevated metabolism or increases in energy substrate usage that exceed key local thresholds rapidly engage mechanisms that generate hyperpolarizing electrical signals in capillaries that then relax contractile elements throughout the vasculature to quickly adjust blood flow to meet changing needs. The attendant increase in energy substrate delivery serves to meet local metabolic requirements and thus avoids a mismatch in supply and demand and prevents metabolic stress. We discuss in detail key examples of EMS that our laboratories have discovered in the brain and the heart, and we outline potential further EMS mechanisms operating in tissues such as skeletal muscle, pancreas, and kidney. We suggest that the energy imbalance evoked by EMS uncoupling may be central to cellular dysfunction from which the hallmarks of aging and metabolic diseases emerge and may lead to generalized organ failure states-such as diverse flavors of heart failure and dementia. Understanding and manipulating EMS may be key to preventing or reversing these dysfunctions.
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Affiliation(s)
- Thomas A. Longden
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - W. Jonathan Lederer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
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4
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Harraz OF, Delpire E. Recent insights into channelopathies. Physiol Rev 2024; 104:23-31. [PMID: 37561136 DOI: 10.1152/physrev.00022.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 07/12/2023] [Accepted: 08/05/2023] [Indexed: 08/11/2023] Open
Affiliation(s)
- Osama F Harraz
- Department of Pharmacology, Larner College of Medicine, Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, Vermont, United States
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University Medical School, Nashville, Tennessee, United States
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee, United States
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5
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Moccia F, Brunetti V, Soda T, Berra-Romani R, Scarpellino G. Cracking the Endothelial Calcium (Ca 2+) Code: A Matter of Timing and Spacing. Int J Mol Sci 2023; 24:16765. [PMID: 38069089 PMCID: PMC10706333 DOI: 10.3390/ijms242316765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 11/16/2023] [Accepted: 11/24/2023] [Indexed: 12/18/2023] Open
Abstract
A monolayer of endothelial cells lines the innermost surface of all blood vessels, thereby coming into close contact with every region of the body and perceiving signals deriving from both the bloodstream and parenchymal tissues. An increase in intracellular Ca2+ concentration ([Ca2+]i) is the main mechanism whereby vascular endothelial cells integrate the information conveyed by local and circulating cues. Herein, we describe the dynamics and spatial distribution of endothelial Ca2+ signals to understand how an array of spatially restricted (at both the subcellular and cellular levels) Ca2+ signals is exploited by the vascular intima to fulfill this complex task. We then illustrate how local endothelial Ca2+ signals affect the most appropriate vascular function and are integrated to transmit this information to more distant sites to maintain cardiovascular homeostasis. Vasorelaxation and sprouting angiogenesis were selected as an example of functions that are finely tuned by the variable spatio-temporal profile endothelial Ca2+ signals. We further highlighted how distinct Ca2+ signatures regulate the different phases of vasculogenesis, i.e., proliferation and migration, in circulating endothelial precursors.
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Affiliation(s)
- Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.B.); (G.S.)
| | - Valentina Brunetti
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.B.); (G.S.)
| | - Teresa Soda
- Department of Health Sciences, University of Magna Graecia, 88100 Catanzaro, Italy;
| | - Roberto Berra-Romani
- Department of Biomedicine, School of Medicine, Benemérita Universidad Autónoma de Puebla, Puebla 72410, Mexico;
| | - Giorgia Scarpellino
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.B.); (G.S.)
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6
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Ferris HR, Stine NC, Hill-Eubanks DC, Nelson MT, Wellman GC, Koide M. Epidermal Growth Factor Receptors in Vascular Endothelial Cells Contribute to Functional Hyperemia in the Brain. Int J Mol Sci 2023; 24:16284. [PMID: 38003472 PMCID: PMC10671586 DOI: 10.3390/ijms242216284] [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: 09/15/2023] [Revised: 11/06/2023] [Accepted: 11/12/2023] [Indexed: 11/26/2023] Open
Abstract
Functional hyperemia-activity-dependent increases in local blood perfusion-underlies the on-demand delivery of blood to regions of enhanced neuronal activity, a process that is crucial for brain health. Importantly, functional hyperemia deficits have been linked to multiple dementia risk factors, including aging, chronic hypertension, and cerebral small vessel disease (cSVD). We previously reported crippled functional hyperemia in a mouse model of genetic cSVD that was likely caused by depletion of phosphatidylinositol 4,5-bisphosphate (PIP2) in capillary endothelial cells (EC) downstream of impaired epidermal growth factor receptor (EGFR) signaling. Here, using EC-specific EGFR-knockout (KO) mice, we directly examined the role of endothelial EGFR signaling in functional hyperemia, assessed by measuring increases in cerebral blood flow in response to contralateral whisker stimulation using laser Doppler flowmetry. Molecular characterizations showed that EGFR expression was dramatically decreased in freshly isolated capillaries from EC-EGFR-KO mice, as expected. Notably, whisker stimulation-induced functional hyperemia was significantly impaired in these mice, an effect that was rescued by administration of PIP2, but not by the EGFR ligand, HB-EGF. These data suggest that the deletion of the EGFR specifically in ECs attenuates functional hyperemia, likely via depleting PIP2 and subsequently incapacitating Kir2.1 channel functionality in capillary ECs. Thus, our study underscores the role of endothelial EGFR signaling in functional hyperemia of the brain.
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Affiliation(s)
- Hannah R. Ferris
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT 05405, USA; (H.R.F.); (N.C.S.)
| | - Nathan C. Stine
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT 05405, USA; (H.R.F.); (N.C.S.)
| | - David C. Hill-Eubanks
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT 05405, USA; (H.R.F.); (N.C.S.)
| | - Mark T. Nelson
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT 05405, USA; (H.R.F.); (N.C.S.)
- Vermont Center for Cardiovascular and Brain Health, Larner College of Medicine University of Vermont, Burlington, VT 05405, USA
- Division of Cardiovascular Sciences, University of Manchester, Manchester M13 9PL, UK
| | - George C. Wellman
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT 05405, USA; (H.R.F.); (N.C.S.)
| | - Masayo Koide
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT 05405, USA; (H.R.F.); (N.C.S.)
- Vermont Center for Cardiovascular and Brain Health, Larner College of Medicine University of Vermont, Burlington, VT 05405, USA
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7
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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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8
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Alarcon-Martinez L, Shiga Y, Villafranca-Baughman D, Cueva Vargas JL, Vidal Paredes IA, Quintero H, Fortune B, Danesh-Meyer H, Di Polo A. Neurovascular dysfunction in glaucoma. Prog Retin Eye Res 2023; 97:101217. [PMID: 37778617 DOI: 10.1016/j.preteyeres.2023.101217] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/23/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
Retinal ganglion cells, the neurons that die in glaucoma, are endowed with a high metabolism requiring optimal provision of oxygen and nutrients to sustain their activity. The timely regulation of blood flow is, therefore, essential to supply firing neurons in active areas with the oxygen and glucose they need for energy. Many glaucoma patients suffer from vascular deficits including reduced blood flow, impaired autoregulation, neurovascular coupling dysfunction, and blood-retina/brain-barrier breakdown. These processes are tightly regulated by a community of cells known as the neurovascular unit comprising neurons, endothelial cells, pericytes, Müller cells, astrocytes, and microglia. In this review, the neurovascular unit takes center stage as we examine the ability of its members to regulate neurovascular interactions and how their function might be altered during glaucomatous stress. Pericytes receive special attention based on recent data demonstrating their key role in the regulation of neurovascular coupling in physiological and pathological conditions. Of particular interest is the discovery and characterization of tunneling nanotubes, thin actin-based conduits that connect distal pericytes, which play essential roles in the complex spatial and temporal distribution of blood within the retinal capillary network. We discuss cellular and molecular mechanisms of neurovascular interactions and their pathophysiological implications, while highlighting opportunities to develop strategies for vascular protection and regeneration to improve functional outcomes in glaucoma.
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Affiliation(s)
- Luis Alarcon-Martinez
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada; Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia
| | - Yukihiro Shiga
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Deborah Villafranca-Baughman
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Jorge L Cueva Vargas
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Isaac A Vidal Paredes
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Heberto Quintero
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Healthy, Portland, OR, USA
| | - Helen Danesh-Meyer
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Adriana Di Polo
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada.
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9
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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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10
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Fang X, Border JJ, Rivers PL, Zhang H, Williams JM, Fan F, Roman RJ. Amyloid beta accumulation in TgF344-AD rats is associated with reduced cerebral capillary endothelial Kir2.1 expression and neurovascular uncoupling. GeroScience 2023; 45:2909-2926. [PMID: 37326915 PMCID: PMC10643802 DOI: 10.1007/s11357-023-00841-2] [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: 04/21/2023] [Accepted: 05/25/2023] [Indexed: 06/17/2023] Open
Abstract
Alzheimer's disease (AD) exerts a tremendous socio-economic burden worldwide. Although reduced cerebral blood flow is an early and persistent symptom that precedes the loss of cognitive function in AD, the underlying molecular and cellular mechanisms remain unclear. The present study investigated whether capillary endothelial inward rectifier potassium 2 (Kir2.1) expression is reduced in TgF344-AD (AD) rats and contributes to neurovascular uncoupling and cognitive deficits in AD. Three- to fourteen-month-old AD rats expressing mutant human APP and PS1 and age-matched wild-type (WT) F344 rats were studied. AD rats exhibited higher amyloid beta (Aβ) expression in the brain as early as 3 months of age and amyloid plaques by 4 months of age. Functional hyperemic responses induced by whisker stimulation were impaired at 4 months of age, which were exacerbated in 6-month- and 14-month-old AD rats. The expression of Kir2.1 protein was significantly lower in the brains of 6-month-old AD versus WT rats, and Kir2.1 coverage was lower in the cerebral microvasculature of AD than in WT rats. Aβ1-42 reduced the Kir2.1 expression in cultured capillary endothelial cells. Cerebral parenchymal arterioles with attached capillaries exhibited a reduced vasodilator in response to 10 mM K+ applied to capillaries, and constricted less following administration of a Kir2.1 channel blocker, compared to WT vessels. These results indicate that capillary endothelial Kir2.1 expression is reduced and contributes to impaired functional hyperemia in AD rats at early ages, perhaps secondary to elevated Aβ expression.
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Affiliation(s)
- Xing Fang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA
| | - Jane J Border
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA
| | - Patrice L Rivers
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA
| | - Huawei Zhang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA
| | - Jan Michael Williams
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA
| | - Fan Fan
- Department of Physiology, Medical College of Georgia, Augusta University, 1462 Laney Walker Blvd, Augusta, GA, 30912, USA.
| | - Richard J Roman
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA.
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11
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Ferris HR, Hill-Eubanks DC, Nelson MT, Wellman GC, Koide M. Epidermal growth factor receptors in vascular endothelial cells contribute to functional hyperemia in the brain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.15.557981. [PMID: 37745396 PMCID: PMC10516026 DOI: 10.1101/2023.09.15.557981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Functional hyperemia - activity-dependent increases in local blood perfusion - underlies the on-demand delivery of blood to regions of enhanced neuronal activity, a process that is crucial for brain health. Importantly, functional hyperemia deficits have been linked to multiple dementia risk factors, including aging, chronic hypertension, and cerebral small vessel disease (cSVD). We previously reported crippled functional hyperemia in a mouse model of genetic cSVD that was likely caused by depletion of phosphatidylinositol 4,5-bisphosphate (PIP2) in capillary endothelial cells (EC) downstream of impaired epidermal growth factor receptor (EGFR) signaling. Here, using EC-specific EGFR-knockout (KO) mice, we directly examined the role of endothelial EGFR signaling in functional hyperemia, assessed by measuring increases in cerebral blood flow in response to contralateral whisker stimulation using laser Doppler flowmetry. Molecular characterizations showed that EGFR expression was dramatically decreased in freshly isolated capillaries from EC-EGFR-KO mice, as expected. Notably, whisker stimulation-induced functional hyperemia was significantly impaired in these mice, an effect that was rescued by exogenous administration of PIP2, but not by the EGFR ligand, HB-EGF. These data suggest that the deletion of the EGFR specifically in ECs depletes PIP2 and attenuates functional hyperemia, underscoring the central role of the endothelial EGFR signaling in cerebral blood flow regulation.
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Affiliation(s)
- Hannah R. Ferris
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT, USA
| | - David C. Hill-Eubanks
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT, USA
| | - Mark T. Nelson
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT, USA
- Vermont Center for Cardiovascular and Brain Health, Larner College of Medicine University of Vermont, Burlington, VT, USA
- Division of Cardiovascular Sciences, University of Manchester, Manchester, UK
| | - George C. Wellman
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT, USA
| | - Masayo Koide
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT, USA
- Vermont Center for Cardiovascular and Brain Health, Larner College of Medicine University of Vermont, Burlington, VT, USA
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12
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Thakore P, Yamasaki E, Ali S, Sanchez Solano A, Labelle-Dumais C, Gao X, Chaumeil MM, Gould DB, Earley S. PI3K block restores age-dependent neurovascular coupling defects associated with cerebral small vessel disease. Proc Natl Acad Sci U S A 2023; 120:e2306479120. [PMID: 37607233 PMCID: PMC10467353 DOI: 10.1073/pnas.2306479120] [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: 04/20/2023] [Accepted: 07/17/2023] [Indexed: 08/24/2023] Open
Abstract
Neurovascular coupling (NVC), a vital physiological process that rapidly and precisely directs localized blood flow to the most active regions of the brain, is accomplished in part by the vast network of cerebral capillaries acting as a sensory web capable of detecting increases in neuronal activity and orchestrating the dilation of upstream parenchymal arterioles. Here, we report a Col4a1 mutant mouse model of cerebral small vessel disease (cSVD) with age-dependent defects in capillary-to-arteriole dilation, functional hyperemia in the brain, and memory. The fundamental defect in aged mutant animals was the depletion of the minor membrane phospholipid phosphatidylinositol 4,5 bisphosphate (PIP2) in brain capillary endothelial cells, leading to the loss of inwardly rectifying K+ (Kir2.1) channel activity. Blocking phosphatidylinositol-3-kinase (PI3K), an enzyme that diminishes the bioavailability of PIP2 by converting it to phosphatidylinositol (3, 4, 5)-trisphosphate (PIP3), restored Kir2.1 channel activity, capillary-to-arteriole dilation, and functional hyperemia. In longitudinal studies, chronic PI3K inhibition also improved the memory function of aged Col4a1 mutant mice. Our data suggest that PI3K inhibition is a viable therapeutic strategy for treating defective NVC and cognitive impairment associated with cSVD.
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Affiliation(s)
- Pratish Thakore
- Department of Pharmacology, Center for Molecular and Cellular Signaling in the Cardiovascular System University of Nevada, Reno School of Medicine, Reno, NV89557-0318
| | - Evan Yamasaki
- Department of Pharmacology, Center for Molecular and Cellular Signaling in the Cardiovascular System University of Nevada, Reno School of Medicine, Reno, NV89557-0318
| | - Sher Ali
- Department of Pharmacology, Center for Molecular and Cellular Signaling in the Cardiovascular System University of Nevada, Reno School of Medicine, Reno, NV89557-0318
| | - Alfredo Sanchez Solano
- Department of Pharmacology, Center for Molecular and Cellular Signaling in the Cardiovascular System University of Nevada, Reno School of Medicine, Reno, NV89557-0318
| | - Cassandre Labelle-Dumais
- Department of Ophthalmology and Anatomy, Institute for Human Genetics, University of California San Francisco School of Medicine, San Francisco, CA94143
| | - Xiao Gao
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA94158
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA94143-0628
| | - Myriam M. Chaumeil
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA94158
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA94143-0628
| | - Douglas B. Gould
- Department of Ophthalmology and Anatomy, Institute for Human Genetics, University of California San Francisco School of Medicine, San Francisco, CA94143
| | - Scott Earley
- Department of Pharmacology, Center for Molecular and Cellular Signaling in the Cardiovascular System University of Nevada, Reno School of Medicine, Reno, NV89557-0318
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13
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Berra-Romani R, Brunetti V, Pellavio G, Soda T, Laforenza U, Scarpellino G, Moccia F. Allyl Isothiocianate Induces Ca 2+ Signals and Nitric Oxide Release by Inducing Reactive Oxygen Species Production in the Human Cerebrovascular Endothelial Cell Line hCMEC/D3. Cells 2023; 12:1732. [PMID: 37443764 PMCID: PMC10340171 DOI: 10.3390/cells12131732] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 06/20/2023] [Accepted: 06/24/2023] [Indexed: 07/15/2023] Open
Abstract
Nitric oxide (NO) represents a crucial mediator to regulate cerebral blood flow (CBF) in the human brain both under basal conditions and in response to somatosensory stimulation. An increase in intracellular Ca2+ concentrations ([Ca2+]i) stimulates the endothelial NO synthase to produce NO in human cerebrovascular endothelial cells. Therefore, targeting the endothelial ion channel machinery could represent a promising strategy to rescue endothelial NO signalling in traumatic brain injury and neurodegenerative disorders. Allyl isothiocyanate (AITC), a major active constituent of cruciferous vegetables, was found to increase CBF in non-human preclinical models, but it is still unknown whether it stimulates NO release in human brain capillary endothelial cells. In the present investigation, we showed that AITC evoked a Ca2+-dependent NO release in the human cerebrovascular endothelial cell line, hCMEC/D3. The Ca2+ response to AITC was shaped by both intra- and extracellular Ca2+ sources, although it was insensitive to the pharmacological blockade of transient receptor potential ankyrin 1, which is regarded to be among the main molecular targets of AITC. In accord, AITC failed to induce transmembrane currents or to elicit membrane hyperpolarization, although NS309, a selective opener of the small- and intermediate-conductance Ca2+-activated K+ channels, induced a significant membrane hyperpolarization. The AITC-evoked Ca2+ signal was triggered by the production of cytosolic, but not mitochondrial, reactive oxygen species (ROS), and was supported by store-operated Ca2+ entry (SOCE). Conversely, the Ca2+ response to AITC did not require Ca2+ mobilization from the endoplasmic reticulum, lysosomes or mitochondria. However, pharmacological manipulation revealed that AITC-dependent ROS generation inhibited plasma membrane Ca2+-ATPase (PMCA) activity, thereby attenuating Ca2+ removal across the plasma membrane and resulting in a sustained increase in [Ca2+]i. In accord, the AITC-evoked NO release was driven by ROS generation and required ROS-dependent inhibition of PMCA activity. These data suggest that AITC could be exploited to restore NO signalling and restore CBF in brain disorders that feature neurovascular dysfunction.
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Affiliation(s)
- Roberto Berra-Romani
- Department of Biomedicine, School of Medicine, Benemérita Universidad Autónoma de Puebla, Puebla 72410, Mexico;
| | - Valentina Brunetti
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.B.); (G.S.)
| | - Giorgia Pellavio
- Department of Molecular Medicine, University of Pavia, 27100 Pavia, Italy; (G.P.); (U.L.)
| | - Teresa Soda
- Department of Health Sciences, University of Magna Graecia, 88100 Catanzaro, Italy;
| | - Umberto Laforenza
- Department of Molecular Medicine, University of Pavia, 27100 Pavia, Italy; (G.P.); (U.L.)
| | - Giorgia Scarpellino
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.B.); (G.S.)
| | - Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.B.); (G.S.)
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14
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Suzuki H, Takeda H, Takuwa H, Ji B, Higuchi M, Kanno I, Masamoto K. Capillary responses to functional and pathological activations rely on the capillary states at rest. J Cereb Blood Flow Metab 2023; 43:1010-1024. [PMID: 36752020 PMCID: PMC10196750 DOI: 10.1177/0271678x231156372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 01/09/2023] [Accepted: 01/19/2023] [Indexed: 02/09/2023]
Abstract
Brain capillaries play a crucial role in maintaining cellular viability and thus preventing neurodegeneration. The aim of this study was to characterize the brain capillary morphology at rest and during neural activation based on a big data analysis from three-dimensional microangiography. Neurovascular responses were measured using a genetic calcium sensor expressed in neurons and microangiography with two-photon microscopy, while neural acivity was modulated by stimulation of contralateral whiskers or by a seizure evoked by kainic acid. For whisker stimulation, 84% of the capillary sites showed no detectable diameter change. The remaining 10% and 6% were dilated and constricted, respectively. Significant differences were observed for capillaries in the diameter at rest between the locations of dilation and constriction. Even the seizures resulted in 44% of the capillaries having no detectable change in diameter, while 56% of the capillaries dilated. The extent of dilation was dependent on the diameter at rest. In conclusion, big data analysis on brain capillary morphology has identified at least two types of capillary states: capillaries with diameters that are relatively large at rest and stable over time regardless of neural activity and capillaries whose diameters are relatively small at rest and vary according to neural activity.
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Affiliation(s)
- Hiroki Suzuki
- Graduate School of
Informatics and Engineering, University of Electro-Communications,
Tokyo, Japan
| | - Hiroshi Takeda
- Graduate School of
Informatics and Engineering, University of Electro-Communications,
Tokyo, Japan
| | - Hiroyuki Takuwa
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
| | - Bin Ji
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
- Department of Radiopharmacy
and Molecular Imaging, School of Pharmacy, Fudan University, Shanghai,
China
| | - Makoto Higuchi
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
| | - Iwao Kanno
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
| | - Kazuto Masamoto
- Graduate School of
Informatics and Engineering, University of Electro-Communications,
Tokyo, Japan
- Department of Functional
Brain Imaging, National Institutes for Quantum Science and Technology,
Chiba, Japan
- Center for Neuroscience and
Biomedical Engineering, University of Electro-Communications, Tokyo,
Japan
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15
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Hashimoto Y, Greene C, Munnich A, Campbell M. The CLDN5 gene at the blood-brain barrier in health and disease. Fluids Barriers CNS 2023; 20:22. [PMID: 36978081 PMCID: PMC10044825 DOI: 10.1186/s12987-023-00424-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023] Open
Abstract
The CLDN5 gene encodes claudin-5 (CLDN-5) that is expressed in endothelial cells and forms tight junctions which limit the passive diffusions of ions and solutes. The blood-brain barrier (BBB), composed of brain microvascular endothelial cells and associated pericytes and end-feet of astrocytes, is a physical and biological barrier to maintain the brain microenvironment. The expression of CLDN-5 is tightly regulated in the BBB by other junctional proteins in endothelial cells and by supports from pericytes and astrocytes. The most recent literature clearly shows a compromised BBB with a decline in CLDN-5 expression increasing the risks of developing neuropsychiatric disorders, epilepsy, brain calcification and dementia. The purpose of this review is to summarize the known diseases associated with CLDN-5 expression and function. In the first part of this review, we highlight the recent understanding of how other junctional proteins as well as pericytes and astrocytes maintain CLDN-5 expression in brain endothelial cells. We detail some drugs that can enhance these supports and are being developed or currently in use to treat diseases associated with CLDN-5 decline. We then summarise mutagenesis-based studies which have facilitated a better understanding of the physiological role of the CLDN-5 protein at the BBB and have demonstrated the functional consequences of a recently identified pathogenic CLDN-5 missense mutation from patients with alternating hemiplegia of childhood. This mutation is the first gain-of-function mutation identified in the CLDN gene family with all others representing loss-of-function mutations resulting in mis-localization of CLDN protein and/or attenuated barrier function. Finally, we summarize recent reports about the dosage-dependent effect of CLDN-5 expression on the development of neurological diseases in mice and discuss what cellular supports for CLDN-5 regulation are compromised in the BBB in human diseases.
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Affiliation(s)
- Yosuke Hashimoto
- Trinity College Dublin, Smurfit Institute of Genetics, Dublin, D02 VF25, Ireland.
| | - Chris Greene
- Trinity College Dublin, Smurfit Institute of Genetics, Dublin, D02 VF25, Ireland
| | - Arnold Munnich
- Institut Imagine, INSERM UMR1163, Université Paris Cité, Paris, F-75015, France
- Departments of Pediatric Neurology and Medical Genetics, Hospital Necker Enfants Malades, Université Paris Cité, Paris, F-75015, France
| | - Matthew Campbell
- Trinity College Dublin, Smurfit Institute of Genetics, Dublin, D02 VF25, Ireland.
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16
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Thakore P, Yamasaki E, Ali S, Solano AS, Labelle-Dumais C, Gao X, Chaumeil MM, Gould DB, Earley S. PI3K block restores age-dependent neurovascular coupling defects associated with cerebral small vessel disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.03.531032. [PMID: 36945616 PMCID: PMC10028793 DOI: 10.1101/2023.03.03.531032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/10/2023]
Abstract
Neurovascular coupling (NVC), a vital physiological process that rapidly and precisely directs localized blood flow to the most active regions of the brain, is accomplished in part by the vast network of cerebral capillaries acting as a sensory web capable of detecting increases in neuronal activity and orchestrating the dilation of upstream parenchymal arterioles. Here, we report a Col4a1 mutant mouse model of cerebral small vessel disease (cSVD) with age-dependent defects in capillary-to-arteriole dilation, functional hyperemia in the brain, and memory. The fundamental defect in aged mutant animals was the depletion of the minor membrane phospholipid phosphatidylinositol 4,5 bisphosphate (PIP 2 ) in brain capillary endothelial cells, leading to the loss of inwardly rectifier K + (Kir2.1) channel activity. Blocking phosphatidylinositol-3-kinase (PI3K), an enzyme that diminishes the bioavailability of PIP 2 by converting it to phosphatidylinositol (3,4,5)-trisphosphate (PIP 3 ), restored Kir2.1 channel activity, capillary-to-arteriole dilation, and functional hyperemia. In longitudinal studies, chronic PI3K inhibition also improved the memory function of aged Col4a1 mutant mice. Our data suggest that PI3K inhibition is a viable therapeutic strategy for treating defective NVC and cognitive impairment associated with cSVD. One-sentence summary PI3K inhibition rescues neurovascular coupling defects in cerebral small vessel disease.
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17
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Abstract
Pericytes, attached to the surface of capillaries, play an important role in regulating local blood flow. Using optogenetic tools and genetically encoded reporters in conjunction with confocal and multiphoton imaging techniques, the 3D structure, anatomical organization, and physiology of pericytes have recently been the subject of detailed examination. This work has revealed novel functions of pericytes and morphological features such as tunneling nanotubes in brain and tunneling microtubes in heart. Here, we discuss the state of our current understanding of the roles of pericytes in blood flow control in brain and heart, where functions may differ due to the distinct spatiotemporal metabolic requirements of these tissues. We also outline the novel concept of electro-metabolic signaling, a universal mechanistic framework that links tissue metabolic state with blood flow regulation by pericytes and vascular smooth muscle cells, with capillary KATP and Kir2.1 channels as primary sensors. Finally, we present major unresolved questions and outline how they can be addressed.
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Affiliation(s)
- Thomas A Longden
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Guiling Zhao
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Ashwini Hariharan
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - W Jonathan Lederer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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18
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Negri S, Sanford M, Shi H, Tarantini S. The role of endothelial TRP channels in age-related vascular cognitive impairment and dementia. Front Aging Neurosci 2023; 15:1149820. [PMID: 37020858 PMCID: PMC10067599 DOI: 10.3389/fnagi.2023.1149820] [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: 01/23/2023] [Accepted: 02/28/2023] [Indexed: 04/07/2023] Open
Abstract
Transient receptor potential (TRP) proteins are part of a superfamily of polymodal cation channels that can be activated by mechanical, physical, and chemical stimuli. In the vascular endothelium, TRP channels regulate two fundamental parameters: the membrane potential and the intracellular Ca2+ concentration [(Ca2+)i]. TRP channels are widely expressed in the cerebrovascular endothelium, and are emerging as important mediators of several brain microvascular functions (e.g., neurovascular coupling, endothelial function, and blood-brain barrier permeability), which become impaired with aging. Aging is the most significant risk factor for vascular cognitive impairment (VCI), and the number of individuals affected by VCI is expected to exponentially increase in the coming decades. Yet, there are currently no preventative or therapeutic treatments available against the development and progression of VCI. In this review, we discuss the involvement of endothelial TRP channels in diverse physiological processes in the brain as well as in the pathogenesis of age-related VCI to explore future potential neuroprotective strategies.
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Affiliation(s)
- Sharon Negri
- Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging/Center for Geroscience and Healthy Brain Aging, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, Hungary
| | - Madison Sanford
- Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging/Center for Geroscience and Healthy Brain Aging, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, Hungary
| | - Helen Shi
- Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging/Center for Geroscience and Healthy Brain Aging, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Stefano Tarantini
- Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging/Center for Geroscience and Healthy Brain Aging, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, Hungary
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- *Correspondence: Stefano Tarantini,
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19
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Bracko O, Harraz OF. Editorial: Small and mighty: Brain capillaries in health and disease. Front Mol Neurosci 2022; 15:1108978. [PMID: 36583082 PMCID: PMC9792964 DOI: 10.3389/fnmol.2022.1108978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Accepted: 11/29/2022] [Indexed: 12/15/2022] Open
Affiliation(s)
- Oliver Bracko
- Department of Biology, University of Miami, Coral Gables, FL, United States,Department of Neurology, University of Miami-Miller School of Medicine, Miami, FL, United States,*Correspondence: Oliver Bracko
| | - Osama F. Harraz
- Department of Pharmacology, Larner College of Medicine, and Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, VT, United States,Osama F. Harraz
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20
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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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21
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Jeffrey DA, Fontaine JT, Dabertrand F. Ex vivo capillary-parenchymal arteriole approach to study brain pericyte physiology. NEUROPHOTONICS 2022; 9:031919. [PMID: 36278784 PMCID: PMC9225307 DOI: 10.1117/1.nph.9.3.031919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 06/01/2022] [Indexed: 06/16/2023]
Abstract
Significance Vascular mural cells, defined as smooth muscle cells (SMCs) and pericytes, influence brain microcirculation, but how they contribute is not fully understood. Most approaches used to investigate pericyte and capillary interactions include ex vivo retinal/slice preparations or in vivo two-photon microscopy. However, neither method adequately captures mural cell behavior without interfering neuronal tissue. Thus, there is a need to isolate vessels with their respective mural cells to study functional and pathological changes. Aim The aim of our work was to implement an ex vivo method that recapitulates vessel dynamics in the brain. Approach Expanding upon our established ex vivo capillary-parenchymal arteriole (CaPA) preparation, we isolated and pressurized arteriole-capillary branches. Using Alexa Fluor™ 633 Hydrazide, we distinguished arterioles (containing elastin) versus capillaries (lacking elastin). In addition, our transgenic SMMHC-GCaMP6f mice allowed for us to visualize mural cell morphology andCa 2 + signals. Lastly, isolated microvasculature was cultured in DMEM media (up to 72 h), mounted, and pressurized using our CaPA preparation. Results U46619 induced a decrease in capillary lumen diameter using both a bath perfusion and local application. In addition, U46619 increasedCa 2 + signaling both globally and locally in contractile pericytes. In our SMMHC-GCaMP6f mice, we saw that thin strand pericytes had sparse processes while contractile pericytes had long, thick processes that wrapped around the lumen of the capillary. Fresh and cultured pericytes constricted in response to U46619 to the same level, and upstream arteriolar dilation induced by capillary stimulation with 10 mMK + remained unchanged by culture conditions adding another application of longer treatment to our approach. Conclusion Our ex vivo CaPA methodology facilitates observation of arteriolar SMC and pericyte dynamic changes in real-time without environmental factors. This method will help to better understand how mural cells differ based on microvasculature location.
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Affiliation(s)
- Danielle A. Jeffrey
- University of Colorado Anschutz Medical Campus, Department of Anesthesiology, Aurora, Colorado, United States
| | - Jackson T. Fontaine
- University of Colorado Anschutz Medical Campus, Department of Anesthesiology, Aurora, Colorado, United States
| | - Fabrice Dabertrand
- University of Colorado Anschutz Medical Campus, Department of Anesthesiology, Aurora, Colorado, United States
- University of Colorado Anschutz Medical Campus, Department of Pharmacology, Aurora, Colorado, United States
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22
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Lansdell TA, Chambers LC, Dorrance AM. Endothelial Cells and the Cerebral Circulation. Compr Physiol 2022; 12:3449-3508. [PMID: 35766836 DOI: 10.1002/cphy.c210015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Endothelial cells form the innermost layer of all blood vessels and are the only vascular component that remains throughout all vascular segments. The cerebral vasculature has several unique properties not found in the peripheral circulation; this requires that the cerebral endothelium be considered as a unique entity. Cerebral endothelial cells perform several functions vital for brain health. The cerebral vasculature is responsible for protecting the brain from external threats carried in the blood. The endothelial cells are central to this requirement as they form the basis of the blood-brain barrier. The endothelium also regulates fibrinolysis, thrombosis, platelet activation, vascular permeability, metabolism, catabolism, inflammation, and white cell trafficking. Endothelial cells regulate the changes in vascular structure caused by angiogenesis and artery remodeling. Further, the endothelium contributes to vascular tone, allowing proper perfusion of the brain which has high energy demands and no energy stores. In this article, we discuss the basic anatomy and physiology of the cerebral endothelium. Where appropriate, we discuss the detrimental effects of high blood pressure on the cerebral endothelium and the contribution of cerebrovascular disease endothelial dysfunction and dementia. © 2022 American Physiological Society. Compr Physiol 12:3449-3508, 2022.
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Affiliation(s)
- Theresa A Lansdell
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, 48824, USA
| | - Laura C Chambers
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, 48824, USA
| | - Anne M Dorrance
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, 48824, USA
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23
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Functionally linked potassium channel activity in cerebral endothelial and smooth muscle cells is compromised in Alzheimer's disease. Proc Natl Acad Sci U S A 2022; 119:e2204581119. [PMID: 35727988 PMCID: PMC9245656 DOI: 10.1073/pnas.2204581119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Patients with Alzheimer’s disease show hypoperfusion of the brain and this may contribute to disease progression. To elucidate underlying mechanisms, we studied pial arteries from 18-mo-old mice with Alzheimer’s disease due to overexpression of amyloid precursor protein. We found enhanced pressure-induced constriction of arteries because of reduction in ryanodine receptor-mediated, local calcium-release events (“Ca2+ sparks”) in arterial smooth muscle cells and a consequent decrease in the activity of large-conductance Ca2+-activated K+ (BK) channels. This phenotype was partially recapitulated by application of an amyloid-β peptide to healthy arteries. Our results will direct further research to restore cerebrovascular function, which is damaged in Alzheimer’s disease, leading to potentially new treatment options. The brain microcirculation is increasingly viewed as a potential target for disease-modifying drugs in the treatment of Alzheimer’s disease patients, reflecting a growing appreciation of evidence that cerebral blood flow is compromised in such patients. However, the pathogenic mechanisms in brain resistance arteries underlying blood flow defects have not yet been elucidated. Here we probed the roles of principal vasodilatory pathways in cerebral arteries using the APP23 mouse model of Alzheimer’s disease, in which amyloid precursor protein is increased approximately sevenfold, leading to neuritic plaques and cerebrovascular accumulation of amyloid-β similar to those in patients with Alzheimer’s disease. Pial arteries from APP23 mice (18 mo old) exhibited enhanced pressure-induced (myogenic) constriction because of a profound reduction in ryanodine receptor-mediated, local calcium-release events (“Ca2+ sparks”) in arterial smooth muscle cells and a consequent decrease in the activity of large-conductance Ca2+-activated K+ (BK) channels. The ability of the endothelial cell inward rectifier K+ (Kir2.1) channel to cause dilation was also compromised. Acute application of amyloid-β 1-40 peptide to cerebral arteries from wild-type mice partially recapitulated the BK dysfunction seen in APP23 mice but had no effect on Kir2.1 function. If mirrored in human Alzheimer’s disease, these tandem defects in K+ channel-mediated vasodilation could account for the clinical cerebrovascular presentation seen in patients: reduced blood flow and crippled functional hyperemia. These data direct future research toward approaches that reverse this dual vascular channel dysfunction, with the ultimate aim of restoring healthy cerebral blood flow and improving clinical outcomes.
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24
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Harraz OF, Klug NR, Senatore AJ, Hill-Eubanks DC, Nelson MT. Piezo1 Is a Mechanosensor Channel in Central Nervous System Capillaries. Circ Res 2022; 130:1531-1546. [PMID: 35382561 PMCID: PMC9106929 DOI: 10.1161/circresaha.122.320827] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Capillaries are equipped to sense neurovascular coupling agents released onto the outer wall of a capillary, translating these external signals into electrical/Ca2+ changes that play a crucial role in blood flow regulation and ensuring that neuronal demands are met. However, control mechanisms attributable to forces imposed onto the lumen are less clear. Here, we show that Piezo1 channels act as mechanosensors in central nervous system capillaries. Electrophysiological analyses confirmed expression and function of Piezo1 channels in brain cortical and retinal capillaries. Activation of Piezo1 channels evoked currents that were sensitive to endothelial cell-specific Piezo1 deletion. Using genetically encoded Ca2+ indicator mice and an ex vivo pressurized retina preparation, we found that activation of Piezo1 channels by mechanical forces triggered Ca2+ signals in capillary endothelial cells. Collectively, these findings indicate that Piezo1 channels are capillary mechanosensors that initiate crucial Ca2+ signals and could, therefore, have a profound impact on central nervous system blood flow control.
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Affiliation(s)
- Osama F. Harraz
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA
- Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, VT, USA
| | - Nicholas R. Klug
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - Amanda J. Senatore
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - David C. Hill-Eubanks
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - Mark T. Nelson
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA
- Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, VT, USA
- Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester, UK
- Geoffrey Jefferson Brain Research Centre, The Manchester Academic Health Science Centre, Northern Care Alliance NHS Group, University of Manchester, UK
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25
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Moccia F, Negri S, Faris P, Angelone T. Targeting endothelial ion signalling to rescue cerebral blood flow in cerebral disorders. Vascul Pharmacol 2022; 145:106997. [DOI: 10.1016/j.vph.2022.106997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/22/2022] [Accepted: 05/02/2022] [Indexed: 10/18/2022]
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26
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Aisenberg WH, McCray BA, Sullivan JM, Diehl E, DeVine LR, Alevy J, Bagnell AM, Carr P, Donohue JK, Goretzki B, Cole RN, Hellmich UA, Sumner CJ. Multiubiquitination of TRPV4 reduces channel activity independent of surface localization. J Biol Chem 2022; 298:101826. [PMID: 35300980 PMCID: PMC9010760 DOI: 10.1016/j.jbc.2022.101826] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 02/19/2022] [Accepted: 02/21/2022] [Indexed: 02/06/2023] Open
Abstract
Ubiquitin (Ub)-mediated regulation of plasmalemmal ion channel activity canonically occurs via stimulation of endocytosis. Whether ubiquitination can modulate channel activity by alternative mechanisms remains unknown. Here, we show that the transient receptor potential vanilloid 4 (TRPV4) cation channel is multiubiquitinated within its cytosolic N-terminal and C-terminal intrinsically disordered regions (IDRs). Mutagenizing select lysine residues to block ubiquitination of the N-terminal but not C-terminal IDR resulted in a marked elevation of TRPV4-mediated intracellular calcium influx, without increasing cell surface expression levels. Conversely, enhancing TRPV4 ubiquitination via expression of an E3 Ub ligase reduced TRPV4 channel activity but did not decrease plasma membrane abundance. These results demonstrate Ub-dependent regulation of TRPV4 channel function independent of effects on plasma membrane localization. Consistent with ubiquitination playing a key negative modulatory role of the channel, gain-of-function neuropathy-causing mutations in the TRPV4 gene led to reduced channel ubiquitination in both cellular and Drosophila models of TRPV4 neuropathy, whereas increasing mutant TRPV4 ubiquitination partially suppressed channel overactivity. Together, these data reveal a novel mechanism via which ubiquitination of an intracellular flexible IDR domain modulates ion channel function independently of endocytic trafficking and identify a contributory role for this pathway in the dysregulation of TRPV4 channel activity by neuropathy-causing mutations.
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Affiliation(s)
- William H Aisenberg
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Brett A McCray
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jeremy M Sullivan
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Erika Diehl
- Department of Chemistry, Biochemistry Section, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Lauren R DeVine
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jonathan Alevy
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Anna M Bagnell
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Patrice Carr
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jack K Donohue
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Benedikt Goretzki
- Institute of Organic Chemistry and Macromolecular Chemistry, Cluster of Excellence 'Balance of the Microverse', Friedrich-Schiller-Universität, Jena, Germany; Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-Universität, Frankfurt am Main, Germany
| | - Robert N Cole
- Institute of Organic Chemistry and Macromolecular Chemistry, Cluster of Excellence 'Balance of the Microverse', Friedrich-Schiller-Universität, Jena, Germany
| | - Ute A Hellmich
- Institute of Organic Chemistry and Macromolecular Chemistry, Cluster of Excellence 'Balance of the Microverse', Friedrich-Schiller-Universität, Jena, Germany; Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-Universität, Frankfurt am Main, Germany
| | - Charlotte J Sumner
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
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27
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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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28
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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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29
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Powell S, Fosi T, Sloneem J, Hawkins C, Richardson H, Aylett S. Neurological presentations and cognitive outcome in Sturge-Weber syndrome. Eur J Paediatr Neurol 2021; 34:21-32. [PMID: 34293629 DOI: 10.1016/j.ejpn.2021.07.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 06/03/2021] [Accepted: 07/07/2021] [Indexed: 11/17/2022]
Abstract
INTRODUCTION This study of children with Sturge-Weber syndrome (SWS) profiled neurological presentations; compared patients with (+) and without (-) port-wine stain (PWS); and determined risk factors for intellectual and language impairments. METHODS A retrospective case note review was conducted at a national centre. RESULTS This cohort (n = 140, male 72, median follow up 114 months) showed sex parity. Intellectual disability ("ID": IQ ≤ 70) affected half (66), being severe (IQ ≤ 40) in two-fifths (27) with ID. Language disorder (core score≤70) affected half (57). Neurological presentations were: status epilepticus 57% (80), hemiplegia 58% (81), headaches 36% (50) and acutely acquired neurological deficits lasting over 24 h 40% (56). One-seventh (20) were PWS(-). This group had: fewer lobes with angioma (p < 0.0001); and less frequent ID (p = 0.002) or language disorder (p = 0.013). Seizure frequency and status epilepticus prevalence did not differ from PWS(+). ID and language disorder were associated with: more lobes with angioma; earlier seizure onset; more frequent status epilepticus and seizure clusters. On multivariable analysis recurrent status epilepticus (p = 0.037) and multi-lobe involvement (p = 0.002) increased the risk of severe intellectual disability. Active epilepsy was associated with language disorder (p = 0.030). CONCLUSIONS This is the largest reported series documenting detailed developmental profiles of children with SWS, including ID and ASD. PWS(+) shows high rates of ID and language disorder. PWS(-) SWS has a more favourable outcome. Cognitive outcome is contingent on number of affected lobes and bilateral involvement. Epilepsy exerts an additional deleterious effect on language and cognition. A high percentage of children have a history of status epilepticus, with evidence that this impacts language and cognitive outcomes. Acutely acquired neurological deficits did not penalise either. Regular structured clinical and developmental assessment permit greater identification of neurological and neurodevelopmental impairments in SWS, and appropriate support.
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Affiliation(s)
- Sebastian Powell
- University College London Medical School, London, Gower Street, WC1E 6BT, United Kingdom.
| | - Tangunu Fosi
- Great Ormond Street Hospital for Children Neurodisability Department, Great Ormond Street, UCL Great Ormond Street Institute of Child Health Clinical Neurosciences, London, United Kingdom
| | - Jenny Sloneem
- Great Ormond Street Hospital for Children Neurodisability Department, Great Ormond Street, London, United Kingdom
| | - Christina Hawkins
- Great Ormond Street Hospital for Children Neurodisability Department, Great Ormond Street, London, United Kingdom
| | - Hanna Richardson
- Great Ormond Street Hospital for Children Neurodisability Department, Great Ormond Street, London, United Kingdom
| | - Sarah Aylett
- Great Ormond Street Hospital for Children Neurodisability Department, Great Ormond Street, UCL Great Ormond Street Institute of Child Health Clinical Neurosciences, London, United Kingdom
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30
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Rosehart AC, Longden TA, Weir N, Fontaine JT, Joutel A, Dabertrand F. Prostaglandin E 2 Dilates Intracerebral Arterioles When Applied to Capillaries: Implications for Small Vessel Diseases. Front Aging Neurosci 2021; 13:695965. [PMID: 34483880 PMCID: PMC8414797 DOI: 10.3389/fnagi.2021.695965] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/15/2021] [Indexed: 11/24/2022] Open
Abstract
Prostaglandin E2 (PGE2) has been widely proposed to mediate neurovascular coupling by dilating brain parenchymal arterioles through activation of prostanoid EP4 receptors. However, our previous report that direct application of PGE2 induces an EP1-mediated constriction strongly argues against its direct action on arterioles during neurovascular coupling, the mechanisms sustaining functional hyperemia. Recent advances have highlighted the role of capillaries in sensing neuronal activity and propagating vasodilatory signals to the upstream penetrating parenchymal arteriole. Here, we examined the effect of capillary stimulation with PGE2 on upstream arteriolar diameter using an ex vivo capillary-parenchymal arteriole preparation and in vivo cerebral blood flow measurements with two-photon laser-scanning microscopy. We found that PGE2 caused upstream arteriolar dilation when applied onto capillaries with an EC50 of 70 nM. The response was inhibited by EP1 receptor antagonist and was greatly reduced, but not abolished, by blocking the strong inward-rectifier K+ channel. We further observed a blunted dilatory response to capillary stimulation with PGE2 in a genetic mouse model of cerebral small vessel disease with impaired functional hyperemia. This evidence casts previous findings in a different light, indicating that capillaries are the locus of PGE2 action to induce upstream arteriolar dilation in the control of brain blood flow, thereby providing a paradigm-shifting view that nonetheless remains coherent with the broad contours of a substantial body of existing literature.
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Affiliation(s)
- Amanda C. Rosehart
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Thomas A. Longden
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Baltimore, MD, United States
| | - Nick Weir
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Baltimore, MD, United States
| | - Jackson T. Fontaine
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Anne Joutel
- INSERM, UMR 1266, GHU Paris Psychiatrie et Neurosciences, Institute of Psychiatry and Neuroscience of Paris, University of Paris, Paris, France
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, United States
| | - Fabrice Dabertrand
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
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31
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Kir Channel Molecular Physiology, Pharmacology, and Therapeutic Implications. Handb Exp Pharmacol 2021; 267:277-356. [PMID: 34345939 DOI: 10.1007/164_2021_501] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
For the past two decades several scholarly reviews have appeared on the inwardly rectifying potassium (Kir) channels. We would like to highlight two efforts in particular, which have provided comprehensive reviews of the literature up to 2010 (Hibino et al., Physiol Rev 90(1):291-366, 2010; Stanfield et al., Rev Physiol Biochem Pharmacol 145:47-179, 2002). In the past decade, great insights into the 3-D atomic resolution structures of Kir channels have begun to provide the molecular basis for their functional properties. More recently, computational studies are beginning to close the time domain gap between in silico dynamic and patch-clamp functional studies. The pharmacology of these channels has also been expanding and the dynamic structural studies provide hope that we are heading toward successful structure-based drug design for this family of K+ channels. In the present review we focus on placing the physiology and pharmacology of this K+ channel family in the context of atomic resolution structures and in providing a glimpse of the promising future of therapeutic opportunities.
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32
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Lynch CE, Eisenbaum M, Algamal M, Balbi M, Ferguson S, Mouzon B, Saltiel N, Ojo J, Diaz-Arrastia R, Mullan M, Crawford F, Bachmeier C. Impairment of cerebrovascular reactivity in response to hypercapnic challenge in a mouse model of repetitive mild traumatic brain injury. J Cereb Blood Flow Metab 2021; 41:1362-1378. [PMID: 33050825 PMCID: PMC8142124 DOI: 10.1177/0271678x20954015] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Incidences of repetitive mild TBI (r-mTBI), like those sustained by contact sports athletes and military personnel, are thought to be a risk factor for development of neurodegenerative disorders. Those suffering from chronic TBI-related illness demonstrate deficits in cerebrovascular reactivity (CVR), the ability of the cerebral vasculature to respond to a vasoactive stimulus. CVR is thus an important measure of traumatic cerebral vascular injury (TCVI), and a possible in vivo endophenotype of TBI-related neuropathogenesis. We combined laser speckle imaging of CVR in response to hypercapnic challenge with neurobehavioral assessment of learning and memory, to investigate if decreased cerebrovascular responsiveness underlies impaired cognitive function in our mouse model of chronic r-mTBI. We demonstrate a profile of blunted hypercapnia-evoked CVR in the cortices of r-mTBI mice like that of human TBI, alongside sustained memory and learning impairment, without biochemical or immunohistopathological signs of cerebral vessel laminar or endothelium constituent loss. Transient decreased expression of alpha smooth muscle actin and platelet-derived growth factor receptor β, indicative of TCVI, is obvious only at the time of the most pronounced CVR deficit. These findings implicate CVR as a valid preclinical measure of TCVI, perhaps useful for developing therapies targeting TCVI after recurrent mild head trauma.
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Affiliation(s)
- Cillian E Lynch
- The Roskamp Institute, Sarasota, FL, USA.,Department of Life Sciences, The Open University, Milton Keynes, UK.,James A. Haley Veteran's Administration, Tampa, FL, USA.,Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Maxwell Eisenbaum
- The Roskamp Institute, Sarasota, FL, USA.,Department of Life Sciences, The Open University, Milton Keynes, UK
| | - Moustafa Algamal
- The Roskamp Institute, Sarasota, FL, USA.,Department of Life Sciences, The Open University, Milton Keynes, UK
| | - Matilde Balbi
- Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Scott Ferguson
- The Roskamp Institute, Sarasota, FL, USA.,Department of Life Sciences, The Open University, Milton Keynes, UK
| | - Benoit Mouzon
- The Roskamp Institute, Sarasota, FL, USA.,Department of Life Sciences, The Open University, Milton Keynes, UK.,James A. Haley Veteran's Administration, Tampa, FL, USA
| | | | - Joseph Ojo
- The Roskamp Institute, Sarasota, FL, USA.,Department of Life Sciences, The Open University, Milton Keynes, UK.,James A. Haley Veteran's Administration, Tampa, FL, USA
| | - Ramon Diaz-Arrastia
- Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Mike Mullan
- The Roskamp Institute, Sarasota, FL, USA.,Department of Life Sciences, The Open University, Milton Keynes, UK
| | - Fiona Crawford
- The Roskamp Institute, Sarasota, FL, USA.,Department of Life Sciences, The Open University, Milton Keynes, UK.,James A. Haley Veteran's Administration, Tampa, FL, USA
| | - Corbin Bachmeier
- The Roskamp Institute, Sarasota, FL, USA.,Department of Life Sciences, The Open University, Milton Keynes, UK.,Bay Pines VA Healthcare System, Bay Pines, FL, USA
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33
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Mughal A, Sackheim AM, Sancho M, Longden TA, Russell S, Lockette W, Nelson MT, Freeman K. Impaired capillary-to-arteriolar electrical signaling after traumatic brain injury. J Cereb Blood Flow Metab 2021; 41:1313-1327. [PMID: 33050826 PMCID: PMC8142130 DOI: 10.1177/0271678x20962594] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/28/2020] [Accepted: 08/31/2020] [Indexed: 12/20/2022]
Abstract
Traumatic brain injury (TBI) acutely impairs dynamic regulation of local cerebral blood flow, but long-term (>72 h) effects on functional hyperemia are unknown. Functional hyperemia depends on capillary endothelial cell inward rectifier potassium channels (Kir2.1) responding to potassium (K+) released during neuronal activity to produce a regenerative, hyperpolarizing electrical signal that propagates from capillaries to dilate upstream penetrating arterioles. We hypothesized that TBI causes widespread disruption of electrical signaling from capillaries-to-arterioles through impairment of Kir2.1 channel function. We randomized mice to TBI or control groups and allowed them to recover for 4 to 7 days post-injury. We measured in vivo cerebral hemodynamics and arteriolar responses to local stimulation of capillaries with 10 mM K+ using multiphoton laser scanning microscopy through a cranial window under urethane and α-chloralose anesthesia. Capillary angio-architecture was not significantly affected following injury. However, K+-induced hyperemia was significantly impaired. Electrophysiology recordings in freshly isolated capillary endothelial cells revealed diminished Ba2+-sensitive Kir2.1 currents, consistent with a reduction in channel function. In pressurized cerebral arteries isolated from TBI mice, K+ failed to elicit the vasodilation seen in controls. We conclude that disruption of endothelial Kir2.1 channel function impairs capillary-to-arteriole electrical signaling, contributing to altered cerebral hemodynamics after TBI.
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Affiliation(s)
- Amreen Mughal
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | | | - Maria Sancho
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Thomas A Longden
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Sheila Russell
- Department of Surgery, University of Vermont, Burlington, VT, USA
| | - Warren Lockette
- Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI, USA
| | - Mark T Nelson
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
- Division of Cardiovascular Sciences, University of Manchester, Manchester, UK
| | - Kalev Freeman
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
- Department of Surgery, University of Vermont, Burlington, VT, USA
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34
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Cai YX, Zhang BL, Yu M, Yang YC, Ao X, Zhu D, Wang QS, Lou J, Liang C, Tang LL, Wu MM, Zhang ZR, Ma HP. Cholesterol Stimulates the Transient Receptor Potential Melastatin 4 Channel in mpkCCD c14 Cells. Front Pharmacol 2021; 12:627875. [PMID: 34054517 PMCID: PMC8160378 DOI: 10.3389/fphar.2021.627875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 04/21/2021] [Indexed: 11/24/2022] Open
Abstract
We have shown that cholesterol regulates the activity of ion channels in mouse cortical collecting duct (CCD) mpkCCDc14 cells and that the transient receptor potential melastatin 4 (TRPM4) channel is expressed in these cells. However, whether TRPM4 channel is regulated by cholesterol remains unclear. Here, we performed inside-out patch-clamp experiments and found that inhibition of cholesterol biosynthesis by lovastatin significantly decreased, whereas enrichment of cholesterol with exogenous cholesterol significantly increased, TRPM4 channel open probability (Po) by regulating its sensitivity to Ca2+ in mpkCCDc14 cells. In addition, inside-out patch-clamp data show that acute depletion of cholesterol in the membrane inner leaflet by methyl-β-cyclodextrin (MβCD) significantly reduced TRPM4 Po, which was reversed by exogenous cholesterol. Moreover, immunofluorescence microscopy, Western blot, cell-surface biotinylation, and patch clamp analysis show that neither inhibition of intracellular cholesterol biosynthesis with lovastatin nor application of exogenous cholesterol had effect on TRPM4 channel protein abundance in the plasma membrane of mpkCCDc14 cells. Sucrose density gradient centrifugation studies demonstrate that TRPM4 was mainly located in cholesterol-rich lipid rafts. Lipid-protein overlay experiments show that TRPM4 directly interacted with several anionic phospholipids, including PI(4,5)P2. Depletion of PI(4,5)P2 with either wortmannin or PGE2 abrogated the stimulatory effects of exogenous cholesterol on TRPM4 activity, whereas exogenous PI(4,5)P2 (diC8-PI(4,5)P2, a water-soluble analog) increased the effects. These results suggest that cholesterol stimulates TRPM4 via a PI(4,5)P2-dependent mechanism.
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Affiliation(s)
- Yong-Xu Cai
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Bao-Long Zhang
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Miao Yu
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Yan-Chao Yang
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Xue Ao
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Di Zhu
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Qiu-Shi Wang
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Jie Lou
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Chen Liang
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Liang-Liang Tang
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Ming-Ming Wu
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Zhi-Ren Zhang
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
- NHC Key Laboratory of Cell Transplantation, Harbin Medical University, Harbin, China
| | - He-Ping Ma
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
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35
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PIP 2 as the "coin of the realm" for neurovascular coupling. Proc Natl Acad Sci U S A 2021; 118:2106308118. [PMID: 33952688 DOI: 10.1073/pnas.2106308118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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36
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PIP 2 corrects cerebral blood flow deficits in small vessel disease by rescuing capillary Kir2.1 activity. Proc Natl Acad Sci U S A 2021; 118:2025998118. [PMID: 33875602 PMCID: PMC8092380 DOI: 10.1073/pnas.2025998118] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cerebral small vessel diseases (SVDs) are a central link between stroke and dementia-two comorbidities without specific treatments. Despite the emerging consensus that SVDs are initiated in the endothelium, the early mechanisms remain largely unknown. Deficits in on-demand delivery of blood to active brain regions (functional hyperemia) are early manifestations of the underlying pathogenesis. The capillary endothelial cell strong inward-rectifier K+ channel Kir2.1, which senses neuronal activity and initiates a propagating electrical signal that dilates upstream arterioles, is a cornerstone of functional hyperemia. Here, using a genetic SVD mouse model, we show that impaired functional hyperemia is caused by diminished Kir2.1 channel activity. We link Kir2.1 deactivation to depletion of phosphatidylinositol 4,5-bisphosphate (PIP2), a membrane phospholipid essential for Kir2.1 activity. Systemic injection of soluble PIP2 rapidly restored functional hyperemia in SVD mice, suggesting a possible strategy for rescuing functional hyperemia in brain disorders in which blood flow is disturbed.
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37
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Weir N, Longden TA. Pathologically Entangled: Brain Trauma-Evoked ROS Imbalance Disrupts Kir Channel Function in Distant Peripheral Vessels. FUNCTION (OXFORD, ENGLAND) 2021; 2:zqab021. [PMID: 35330675 PMCID: PMC8788822 DOI: 10.1093/function/zqab021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 01/06/2023]
Affiliation(s)
- Nick Weir
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Thomas A Longden
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, USA,Address correspondence to T.A.L. (e-mail: )
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38
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Negri S, Faris P, Soda T, Moccia F. Endothelial signaling at the core of neurovascular coupling: The emerging role of endothelial inward-rectifier K + (K ir2.1) channels and N-methyl-d-aspartate receptors in the regulation of cerebral blood flow. Int J Biochem Cell Biol 2021; 135:105983. [PMID: 33894355 DOI: 10.1016/j.biocel.2021.105983] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/08/2021] [Accepted: 04/19/2021] [Indexed: 12/21/2022]
Abstract
Neurovascular coupling (NVC) represents the mechanisms whereby an increase in neuronal activity (NA) may lead to local vasodilation and increase in regional cerebral blood flow (CBF). It has long been thought that neurons and astrocytes generate the vasoactive mediators regulating local changes in CBF, whereas cerebrovascular endothelial cells are not able to directly sense NA. Unexpectedly, recent evidence demonstrated that brain microvascular endothelial cells may sense NA through inward-rectifier K+ (Kir2.1) channels and may detect synaptic activity via N-methyl-d-aspartate (NMDA) receptors (NMDARs). In the present perspective, therefore, we discuss the hypothesis that endothelial Kir2.1 channels and NMDARs play a key role in NVC and in CBF regulation, which is crucial to unravel the cellular and molecular underpinnings of blood oxygen level-dependent signals.
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Affiliation(s)
- Sharon Negri
- Department of Biology and Biotechnology "Lazzaro Spallanzani", Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Pawan Faris
- Department of Biology and Biotechnology "Lazzaro Spallanzani", Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Teresa Soda
- Department of Brain and Behavioral Sciences, University if Pavia, Pavia, Italy
| | - Francesco Moccia
- Department of Biology and Biotechnology "Lazzaro Spallanzani", Laboratory of General Physiology, University of Pavia, Pavia, Italy.
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39
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Sackheim AM, Villalba N, Sancho M, Harraz OF, Bonev AD, D’Alessandro A, Nemkov T, Nelson MT, Freeman K. Traumatic Brain Injury Impairs Systemic Vascular Function Through Disruption of Inward-Rectifier Potassium Channels. FUNCTION (OXFORD, ENGLAND) 2021; 2:zqab018. [PMID: 34568829 PMCID: PMC8462507 DOI: 10.1093/function/zqab018] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Trauma can lead to widespread vascular dysfunction, but the underlying mechanisms remain largely unknown. Inward-rectifier potassium channels (Kir2.1) play a critical role in the dynamic regulation of regional perfusion and blood flow. Kir2.1 channel activity requires phosphatidylinositol 4,5-bisphosphate (PIP2), a membrane phospholipid that is degraded by phospholipase A2 (PLA2) in conditions of oxidative stress or inflammation. We hypothesized that PLA2-induced depletion of PIP2 after trauma impairs Kir2.1 channel function. A fluid percussion injury model of traumatic brain injury (TBI) in rats was used to study mesenteric resistance arteries 24 hours after injury. The functional responses of intact arteries were assessed using pressure myography. We analyzed circulating PLA2, hydrogen peroxide (H2O2), and metabolites to identify alterations in signaling pathways associated with PIP2 in TBI. Electrophysiology analysis of freshly-isolated endothelial and smooth muscle cells revealed a significant reduction of Ba2+-sensitive Kir2.1 currents after TBI. Additionally, dilations to elevated extracellular potassium and BaCl2- or ML 133-induced constrictions in pressurized arteries were significantly decreased following TBI, consistent with an impairment of Kir2.1 channel function. The addition of a PIP2 analog to the patch pipette successfully rescued endothelial Kir2.1 currents after TBI. Both H2O2 and PLA2 activity were increased after injury. Metabolomics analysis demonstrated altered lipid metabolism signaling pathways, including increased arachidonic acid, and fatty acid mobilization after TBI. Our findings support a model in which increased H2O2-induced PLA2 activity after trauma hydrolyzes endothelial PIP2, resulting in impaired Kir2.1 channel function.
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Affiliation(s)
- Adrian M Sackheim
- Department of Surgery, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Nuria Villalba
- Department of Surgery, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Maria Sancho
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Osama F Harraz
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Adrian D Bonev
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Angelo D’Alessandro
- Department of Surgery, University of Colorado School of Medicine, Aurora, CO, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Travis Nemkov
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Mark T Nelson
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, USA
- Division of Cardiovascular Sciences, University of Manchester, Manchester, UK
| | - Kalev Freeman
- Department of Surgery, University of Vermont Larner College of Medicine, Burlington, VT, USA
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, USA
- Address correspondence to K.F. (e-mail: )
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40
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Mughal A, Harraz OF, Gonzales AL, Hill-Eubanks D, Nelson MT. PIP 2 Improves Cerebral Blood Flow in a Mouse Model of Alzheimer's Disease. FUNCTION (OXFORD, ENGLAND) 2021; 2:zqab010. [PMID: 33763649 PMCID: PMC7955025 DOI: 10.1093/function/zqab010] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/16/2021] [Accepted: 02/16/2021] [Indexed: 02/05/2023]
Abstract
Alzheimer's disease (AD) is a leading cause of dementia and a substantial healthcare burden. Despite this, few treatment options are available for controlling AD symptoms. Notably, neuronal activity-dependent increases in cortical cerebral blood flow (CBF; functional hyperemia) are attenuated in AD patients, but the associated pathological mechanisms are not fully understood at the molecular level. A fundamental mechanism underlying functional hyperemia is activation of capillary endothelial inward-rectifying K+ (Kir2.1) channels by neuronally derived potassium (K+), which evokes a retrograde capillary-to-arteriole electrical signal that dilates upstream arterioles, increasing blood delivery to downstream active regions. Here, using a mouse model of familial AD (5xFAD), we tested whether this impairment in functional hyperemia is attributable to reduced activity of capillary Kir2.1 channels. In vivo CBF measurements revealed significant reductions in whisker stimulation (WS)-induced and K+-induced hyperemic responses in 5xFAD mice compared with age-matched controls. Notably, measurements of whole-cell currents in freshly isolated 5xFAD capillary endothelial cells showed that Kir2.1 current density was profoundly reduced, suggesting a defect in Kir2.1 function. Because Kir2.1 activity absolutely depends on binding of phosphatidylinositol 4,5-bisphosphate (PIP2) to the channel, we hypothesized that capillary Kir2.1 channel impairment could be corrected by exogenously supplying PIP2. As predicted, a PIP2 analog restored Kir2.1 current density to control levels. More importantly, systemic administration of PIP2 restored K+-induced CBF increases and WS-induced functional hyperemic responses in 5xFAD mice. Collectively, these data provide evidence that PIP2-mediated restoration of capillary endothelial Kir2.1 function improves neurovascular coupling and CBF in the setting of AD.
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Affiliation(s)
- Amreen Mughal
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - Osama F Harraz
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA,Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, VT, USA
| | - Albert L Gonzales
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA,Department of Physiology and Cell Biology, University of Nevada, Reno, School of Medicine, Reno, NV, USA
| | - David Hill-Eubanks
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - Mark T Nelson
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA,Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, VT, USA,Division of Cardiovascular Sciences, University of Manchester, Manchester, UK,Address correspondence to M.T.N. (e-mail: )
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41
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Wolpe AG, Ruddiman CA, Hall PJ, Isakson BE. Polarized Proteins in Endothelium and Their Contribution to Function. J Vasc Res 2021; 58:65-91. [PMID: 33503620 DOI: 10.1159/000512618] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 10/27/2020] [Indexed: 12/11/2022] Open
Abstract
Protein localization in endothelial cells is tightly regulated to create distinct signaling domains within their tight spatial restrictions including luminal membranes, abluminal membranes, and interendothelial junctions, as well as caveolae and calcium signaling domains. Protein localization in endothelial cells is also determined in part by the vascular bed, with differences between arteries and veins and between large and small arteries. Specific protein polarity and localization is essential for endothelial cells in responding to various extracellular stimuli. In this review, we examine protein localization in the endothelium of resistance arteries, with occasional references to other vessels for contrast, and how that polarization contributes to endothelial function and ultimately whole organism physiology. We highlight the protein localization on the luminal surface, discussing important physiological receptors and the glycocalyx. The protein polarization to the abluminal membrane is especially unique in small resistance arteries with the presence of the myoendothelial junction, a signaling microdomain that regulates vasodilation, feedback to smooth muscle cells, and ultimately total peripheral resistance. We also discuss the interendothelial junction, where tight junctions, adherens junctions, and gap junctions all convene and regulate endothelial function. Finally, we address planar cell polarity, or axial polarity, and how this is regulated by mechanosensory signals like blood flow.
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Affiliation(s)
- Abigail G Wolpe
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA.,Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Claire A Ruddiman
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA.,Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Phillip J Hall
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Brant E Isakson
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA, .,Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia, USA,
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42
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Pfeiffer T, Li Y, Attwell D. Diverse mechanisms regulating brain energy supply at the capillary level. Curr Opin Neurobiol 2021; 69:41-50. [PMID: 33485189 DOI: 10.1016/j.conb.2020.12.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/28/2020] [Accepted: 12/13/2020] [Indexed: 02/06/2023]
Abstract
Neural information processing depends critically on the brain's energy supply, which is provided in the form of glucose and oxygen in the blood. Regulation of this supply occurs by smooth muscle and contractile pericytes adjusting the diameter of arterioles and capillaries, respectively. Controversies exist over the relative importance of capillary and arteriolar level control, whether enzymatically generated signals or K+ ions are the dominant controller of cerebral blood flow, and the involvement of capillary endothelial cells. Here, we try to synthesise the relevant recent data into a coherent view of how brain energy supply is controlled and suggest approaches to answering key questions.
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Affiliation(s)
- Thomas Pfeiffer
- Department of Neuroscience, Physiology & Pharmacology, University College London Gower Street, London, WC1E 6BT, UK.
| | - Yuening Li
- Department of Neuroscience, Physiology & Pharmacology, University College London Gower Street, London, WC1E 6BT, UK
| | - David Attwell
- Department of Neuroscience, Physiology & Pharmacology, University College London Gower Street, London, WC1E 6BT, UK.
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43
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Hariharan A, Weir N, Robertson C, He L, Betsholtz C, Longden TA. The Ion Channel and GPCR Toolkit of Brain Capillary Pericytes. Front Cell Neurosci 2020; 14:601324. [PMID: 33390906 PMCID: PMC7775489 DOI: 10.3389/fncel.2020.601324] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/13/2020] [Indexed: 12/14/2022] Open
Abstract
Brain pericytes reside on the abluminal surface of capillaries, and their processes cover ~90% of the length of the capillary bed. These cells were first described almost 150 years ago (Eberth, 1871; Rouget, 1873) and have been the subject of intense experimental scrutiny in recent years, but their physiological roles remain uncertain and little is known of the complement of signaling elements that they employ to carry out their functions. In this review, we synthesize functional data with single-cell RNAseq screens to explore the ion channel and G protein-coupled receptor (GPCR) toolkit of mesh and thin-strand pericytes of the brain, with the aim of providing a framework for deeper explorations of the molecular mechanisms that govern pericyte physiology. We argue that their complement of channels and receptors ideally positions capillary pericytes to play a central role in adapting blood flow to meet the challenge of satisfying neuronal energy requirements from deep within the capillary bed, by enabling dynamic regulation of their membrane potential to influence the electrical output of the cell. In particular, we outline how genetic and functional evidence suggest an important role for Gs-coupled GPCRs and ATP-sensitive potassium (KATP) channels in this context. We put forth a predictive model for long-range hyperpolarizing electrical signaling from pericytes to upstream arterioles, and detail the TRP and Ca2+ channels and Gq, Gi/o, and G12/13 signaling processes that counterbalance this. We underscore critical questions that need to be addressed to further advance our understanding of the signaling topology of capillary pericytes, and how this contributes to their physiological roles and their dysfunction in disease.
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Affiliation(s)
- Ashwini Hariharan
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, United States
| | - Nick Weir
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, United States
| | - Colin Robertson
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, United States
| | - Liqun He
- Rudbeck Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Christer Betsholtz
- Rudbeck Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.,Department of Medicine Huddinge (MedH), Karolinska Institutet & Integrated Cardio Metabolic Centre, Huddinge, Sweden
| | - Thomas A Longden
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD, United States
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44
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Krajnik A, Brazzo JA, Vaidyanathan K, Das T, Redondo-Muñoz J, Bae Y. Phosphoinositide Signaling and Mechanotransduction in Cardiovascular Biology and Disease. Front Cell Dev Biol 2020; 8:595849. [PMID: 33381504 PMCID: PMC7767973 DOI: 10.3389/fcell.2020.595849] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 11/25/2020] [Indexed: 12/14/2022] Open
Abstract
Phosphoinositides, which are membrane-bound phospholipids, are critical signaling molecules located at the interface between the extracellular matrix, cell membrane, and cytoskeleton. Phosphoinositides are essential regulators of many biological and cellular processes, including but not limited to cell migration, proliferation, survival, and differentiation, as well as cytoskeletal rearrangements and actin dynamics. Over the years, a multitude of studies have uniquely implicated phosphoinositide signaling as being crucial in cardiovascular biology and a dominant force in the development of cardiovascular disease and its progression. Independently, the cellular transduction of mechanical forces or mechanotransduction in cardiovascular cells is widely accepted to be critical to their homeostasis and can drive aberrant cellular phenotypes and resultant cardiovascular disease. Given the versatility and diversity of phosphoinositide signaling in the cardiovascular system and the dominant regulation of cardiovascular cell functions by mechanotransduction, the molecular mechanistic overlap and extent to which these two major signaling modalities converge in cardiovascular cells remain unclear. In this review, we discuss and synthesize recent findings that rightfully connect phosphoinositide signaling to cellular mechanotransduction in the context of cardiovascular biology and disease, and we specifically focus on phosphatidylinositol-4,5-phosphate, phosphatidylinositol-4-phosphate 5-kinase, phosphatidylinositol-3,4,5-phosphate, and phosphatidylinositol 3-kinase. Throughout the review, we discuss how specific phosphoinositide subspecies have been shown to mediate biomechanically sensitive cytoskeletal remodeling in cardiovascular cells. Additionally, we discuss the direct interaction of phosphoinositides with mechanically sensitive membrane-bound ion channels in response to mechanical stimuli. Furthermore, we explore the role of phosphoinositide subspecies in association with critical downstream effectors of mechanical signaling in cardiovascular biology and disease.
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Affiliation(s)
- Amanda Krajnik
- Department of Pathology and Anatomical Sciences, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Joseph A Brazzo
- Department of Pathology and Anatomical Sciences, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Kalyanaraman Vaidyanathan
- Department of Pathology and Anatomical Sciences, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Tuhin Das
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, United States
| | - Javier Redondo-Muñoz
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas Margarita Salas, Madrid, Spain.,Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine and Health, School of Biological Sciences, University of Manchester, Manchester, United Kingdom
| | - Yongho Bae
- Department of Pathology and Anatomical Sciences, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
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45
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Quick S, Moss J, Rajani RM, Williams A. A Vessel for Change: Endothelial Dysfunction in Cerebral Small Vessel Disease. Trends Neurosci 2020; 44:289-305. [PMID: 33308877 DOI: 10.1016/j.tins.2020.11.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 09/24/2020] [Accepted: 11/11/2020] [Indexed: 01/08/2023]
Abstract
The blood vessels of the brain are lined with endothelial cells and it has been long known that these help to regulate blood flow to the brain. However, there is increasing evidence that these cells also interact with the surrounding brain tissue. These interactions change when the endothelial cells become dysfunctional and have an impact in diseases such as cerebral small vessel disease, the leading cause of vascular dementia. In this review, we focus on what endothelial dysfunction is, what causes it, how it leads to surrounding brain pathology, how researchers can investigate it with current models, and where this might lead in the future for dementia therapies.
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Affiliation(s)
- Sophie Quick
- Centre for Regenerative Medicine, Institute for Regeneration and Repair, The University of Edinburgh, Edinburgh EH16 4UU, UK
| | - Jonathan Moss
- Centre for Regenerative Medicine, Institute for Regeneration and Repair, The University of Edinburgh, Edinburgh EH16 4UU, UK
| | - Rikesh M Rajani
- UK Dementia Research Institute at UCL, University College London, London, UK
| | - Anna Williams
- Centre for Regenerative Medicine, Institute for Regeneration and Repair, The University of Edinburgh, Edinburgh EH16 4UU, UK.
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46
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Katan M, Cockcroft S. Phospholipase C families: Common themes and versatility in physiology and pathology. Prog Lipid Res 2020; 80:101065. [PMID: 32966869 DOI: 10.1016/j.plipres.2020.101065] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 08/14/2020] [Accepted: 09/17/2020] [Indexed: 12/20/2022]
Abstract
Phosphoinositide-specific phospholipase Cs (PLCs) are expressed in all mammalian cells and play critical roles in signal transduction. To obtain a comprehensive understanding of these enzymes in physiology and pathology, a detailed structural, biochemical, cell biological and genetic information is required. In this review, we cover all these aspects to summarize current knowledge of the entire superfamily. The families of PLCs have expanded from 13 enzymes to 16 with the identification of the atypical PLCs in the human genome. Recent structural insights highlight the common themes that cover not only the substrate catalysis but also the mechanisms of activation. This involves the release of autoinhibitory interactions that, in the absence of stimulation, maintain classical PLC enzymes in their inactive forms. Studies of individual PLCs provide a rich repertoire of PLC function in different physiologies. Furthermore, the genetic studies discovered numerous mutated and rare variants of PLC enzymes and their link to human disease development, greatly expanding our understanding of their roles in diverse pathologies. Notably, substantial evidence now supports involvement of different PLC isoforms in the development of specific cancer types, immune disorders and neurodegeneration. These advances will stimulate the generation of new drugs that target PLC enzymes, and will therefore open new possibilities for treatment of a number of diseases where current therapies remain ineffective.
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Affiliation(s)
- Matilda Katan
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK
| | - Shamshad Cockcroft
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, 21 University Street, London WC1E 6JJ, UK.
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47
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Contractile pericytes determine the direction of blood flow at capillary junctions. Proc Natl Acad Sci U S A 2020; 117:27022-27033. [PMID: 33051294 DOI: 10.1073/pnas.1922755117] [Citation(s) in RCA: 110] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The essential function of the circulatory system is to continuously and efficiently supply the O2 and nutrients necessary to meet the metabolic demands of every cell in the body, a function in which vast capillary networks play a key role. Capillary networks serve an additional important function in the central nervous system: acting as a sensory network, they detect neuronal activity in the form of elevated extracellular K+ and initiate a retrograde, propagating, hyperpolarizing signal that dilates upstream arterioles to rapidly increase local blood flow. Yet, little is known about how blood entering this network is distributed on a branch-to-branch basis to reach specific neurons in need. Here, we demonstrate that capillary-enwrapping projections of junctional, contractile pericytes within a postarteriole transitional region differentially constrict to structurally and dynamically determine the morphology of capillary junctions and thereby regulate branch-specific blood flow. We further found that these contractile pericytes are capable of receiving propagating K+-induced hyperpolarizing signals propagating through the capillary network and dynamically channeling red blood cells toward the initiating signal. By controlling blood flow at junctions, contractile pericytes within a functionally distinct postarteriole transitional region maintain the efficiency and effectiveness of the capillary network, enabling optimal perfusion of the brain.
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48
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Presa JL, Saravia F, Bagi Z, Filosa JA. Vasculo-Neuronal Coupling and Neurovascular Coupling at the Neurovascular Unit: Impact of Hypertension. Front Physiol 2020; 11:584135. [PMID: 33101063 PMCID: PMC7546852 DOI: 10.3389/fphys.2020.584135] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/04/2020] [Indexed: 12/18/2022] Open
Abstract
Components of the neurovascular unit (NVU) establish dynamic crosstalk that regulates cerebral blood flow and maintain brain homeostasis. Here, we describe accumulating evidence for cellular elements of the NVU contributing to critical physiological processes such as cerebral autoregulation, neurovascular coupling, and vasculo-neuronal coupling. We discuss how alterations in the cellular mechanisms governing NVU homeostasis can lead to pathological changes in which vascular endothelial and smooth muscle cell, pericyte and astrocyte function may play a key role. Because hypertension is a modifiable risk factor for stroke and accelerated cognitive decline in aging, we focus on hypertension-associated changes on cerebral arteriole function and structure, and the molecular mechanisms through which these may contribute to cognitive decline. We gather recent emerging evidence concerning cognitive loss in hypertension and the link with vascular dementia and Alzheimer’s disease. Collectively, we summarize how vascular dysfunction, chronic hypoperfusion, oxidative stress, and inflammatory processes can uncouple communication at the NVU impairing cerebral perfusion and contributing to neurodegeneration.
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Affiliation(s)
- Jessica L Presa
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Biología y Medicina Experimental, CONICET, Buenos Aires, Argentina
| | - Flavia Saravia
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Biología y Medicina Experimental, CONICET, Buenos Aires, Argentina
| | - Zsolt Bagi
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Jessica A Filosa
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States
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Drew PJ, Mateo C, Turner KL, Yu X, Kleinfeld D. Ultra-slow Oscillations in fMRI and Resting-State Connectivity: Neuronal and Vascular Contributions and Technical Confounds. Neuron 2020; 107:782-804. [PMID: 32791040 PMCID: PMC7886622 DOI: 10.1016/j.neuron.2020.07.020] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 06/09/2020] [Accepted: 07/15/2020] [Indexed: 12/27/2022]
Abstract
Ultra-slow, ∼0.1-Hz variations in the oxygenation level of brain blood are widely used as an fMRI-based surrogate of "resting-state" neuronal activity. The temporal correlations among these fluctuations across the brain are interpreted as "functional connections" for maps and neurological diagnostics. Ultra-slow variations in oxygenation follow a cascade. First, they closely track changes in arteriole diameter. Second, interpretable functional connections arise when the ultra-slow changes in amplitude of γ-band neuronal oscillations, which are shared across even far-flung but synaptically connected brain regions, entrain the ∼0.1-Hz vasomotor oscillation in diameter of local arterioles. Significant confounds to estimates of functional connectivity arise from residual vasomotor activity as well as arteriole dynamics driven by self-generated movements and subcortical common modulatory inputs. Last, methodological limitations of fMRI can lead to spurious functional connections. The neuronal generator of ultra-slow variations in γ-band amplitude, including that associated with self-generated movements, remains an open issue.
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Affiliation(s)
- Patrick J Drew
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802, USA; Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, USA; Department of Neurosurgery, Pennsylvania State University, University Park, PA 16802, USA
| | - Celine Mateo
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Kevin L Turner
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, USA
| | - Xin Yu
- High-Field Magnetic Resonance Department, Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany; MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA 02114, USA
| | - David Kleinfeld
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA; Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA.
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PIP 2: A critical regulator of vascular ion channels hiding in plain sight. Proc Natl Acad Sci U S A 2020; 117:20378-20389. [PMID: 32764146 PMCID: PMC7456132 DOI: 10.1073/pnas.2006737117] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The phosphoinositide, phosphatidylinositol 4,5-bisphosphate (PIP2), has long been established as a major contributor to intracellular signaling, primarily by virtue of its role as a substrate for phospholipase C (PLC). Signaling by Gq-protein-coupled receptors triggers PLC-mediated hydrolysis of PIP2 into inositol 1,4,5-trisphosphate and diacylglycerol, which are well known to modulate vascular ion channel activity. Often overlooked, however, is the role PIP2 itself plays in this regulation. Although numerous reports have demonstrated that PIP2 is critical for ion channel regulation, how it impacts vascular function has received scant attention. In this review, we focus on PIP2 as a regulator of ion channels in smooth muscle cells and endothelial cells-the two major classes of vascular cells. We further address the concerted effects of such regulation on vascular function and blood flow control. We close with a consideration of current knowledge regarding disruption of PIP2 regulation of vascular ion channels in disease.
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