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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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Skov PV, Sorensen TF, Ramlov H, Steffensen JF. Vascular arrangement and ultrastructure of the European eelpout Zoarces viviparus ovary: implications for maternal-embryonic exchange. Anat Rec (Hoboken) 2008; 290:1500-7. [PMID: 17968861 DOI: 10.1002/ar.20605] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The structural basis for exchange between maternal serum and ovarian fluid in the viviparous teleost Zoarces viviparus was investigated. Casts of the ovarian vasculature showed that blood supply to the ovary is initially directed to the follicular appendages lining the ovarian wall through thick-walled muscular arteries running along the ovary wall and within the follicular appendages. The follicles had a rich capillary network with diffusion distances between maternal blood and ovarian fluid comparable to those found for gill epithelia, suggesting this is the primary site of gas exchange between maternal plasma and ovarian fluid. Follicular capillary beds were continuous with those in the ovary wall and were eventually drained by the ovarian and intestinal venous systems. The barrier between ovarian fluid and maternal blood consisted of the endothelial cells of the maternal blood vessels and a layer of epithelial cells lining the ovarian lumen, with an intermittent layer of loose connective fibers. Junctional complexes between cells were predominantly anchoring junctions with the occurrence of occasional occluding junctions, supporting the possibility of paracellular transport from maternal serum to ovarian fluid of small molecular weight compounds. Heavy investment in keratin filaments suggests that follicles are tissues of high structural integrity. Evidence for protein synthesis in the ovarian lining was found in the form of Golgi apparatus and rough endoplasmic reticulum. Although numerous cytoplasmic vacuoles and secretory granules were present in both epithelial and endothelial cells, the fate of synthesized protein remains to be determined.
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Affiliation(s)
- Peter Vilhelm Skov
- University of Copenhagen, Marine Biological Laboratory, Helsingør, Denmark.
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Ramos RF, Hoying JB, Witte MH, Daniel Stamer W. Schlemm??s Canal Endothelia, Lymphatic, or Blood Vasculature? J Glaucoma 2007; 16:391-405. [PMID: 17571003 DOI: 10.1097/ijg.0b013e3180654ac6] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In the human eye, the final barrier for aqueous humor to cross before returning to systemic circulation is the inner wall of Schlemm's canal. Unfortunately, the specific contribution of the inner wall to total outflow resistance in the conventional pathway is unknown in both normal and glaucomatous eyes. To better understand inner wall physiology, we contrasted it with 2 specialized continuous endothelia, initial lymphatic, and blood capillary endothelia. Specifically, we compare their developmental origin, morphology, junctional complexes, microenvironment, and physiologic responses to different biomechanical factors. Our evaluation concludes that the inner wall of Schlemm's canal is unique, sharing extraordinary characteristics with both types of specialized endothelia in addition to having distinctive features of its own.
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Affiliation(s)
- Renata F Ramos
- Biomedical Engineering Program, The University of Arizona, Tucson, AZ, USA
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Nagasawa K, Chiba H, Fujita H, Kojima T, Saito T, Endo T, Sawada N. Possible involvement of gap junctions in the barrier function of tight junctions of brain and lung endothelial cells. J Cell Physiol 2006; 208:123-32. [PMID: 16547974 DOI: 10.1002/jcp.20647] [Citation(s) in RCA: 188] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Gap-junction plaques are often observed with tight-junction strands of vascular endothelial cells but the molecular interaction and functional relationships between these two junctions remain obscure. We herein show that gap-junction proteins connexin40 (Cx40) and Cx43 are colocalized and coprecipitated with tight-junction molecules occludin, claudin-5, and ZO-1 in porcine blood-brain barrier (BBB) endothelial cells. Gap junction blockers 18beta-glycyrrhetinic acid (18beta-GA) and oleamide (OA) did not influence expression of Cx40, Cx43, occludin, claudin-5, junctional adhesion molecule (JAM)-A, JAM-B, JAM-C, or ZO-1, or their subcellular localization in the porcine BBB endothelial cells. In contrast, these gap-junction blocking agents inhibited the barrier function of tight junctions in cells, determined by measurement of transendothelial electrical resistance and paracellular flux of mannitol and inulin. 18beta-GA also significantly reduced the barrier property in rat lung endothelial (RLE) cells expressing doxycycline-induced claudin-1, but did not change the interaction between Cx43 and either claudin-1 or ZO-1, nor their expression levels or subcellular distribution. These findings suggest that Cx40- and/or Cx43-based gap junctions might be required to maintain the endothelial barrier function without altering the expression and localization of the tight-junction components analyzed.
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Affiliation(s)
- Kunihiko Nagasawa
- Department of Pathology, Sapporo Medical University School of Medicine, Sapporo, Japan
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Lacković V, Kostić V, Sternić N, Kanjuh V, Vuković I. [Angiogenesis in the central nervous system: a role of vascular endothelial growth factor]. VOJNOSANIT PREGL 2005; 62:59-67. [PMID: 15715351 DOI: 10.2298/vsp0501059l] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Dittrich M, Daut J. Voltage-dependent K(+) current in capillary endothelial cells isolated from guinea pig heart. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:H119-27. [PMID: 10409189 DOI: 10.1152/ajpheart.1999.277.1.h119] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Capillary fragments were isolated from guinea pig hearts, and their electrical properties were studied using the perforated-patch and cell-attached mode of the patch-clamp technique. A voltage-dependent K(+) current was discovered that was activated at potentials positive to -20 mV and showed a sigmoid rising phase. For depolarizing voltage steps from -128 to +52 mV, the time to peak was 71 +/- 5 ms (mean +/- SE) and the amplitude of the current was 3.7 +/- 0.5 pA/pF in the presence of 5 mM external K(+). The time course of inactivation was exponential with a time constant of 7.2 +/- 0.5 s at +52 mV. The current was blocked by tetraethylammonium (inhibitory constant approximately 3 mM) but was not affected by charybdotoxin (1 microM) or apamin (1 microM). In the cell-attached mode, depolarization-activated single-channel currents were found that inactivated completely within 30 s; the single-channel conductance was 12.3 +/- 2.4 pS. The depolarization-activated K(+) current described here may play a role in membrane potential oscillations of the endothelium.
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Affiliation(s)
- M Dittrich
- Institut für Normale und Pathologische Physiologie, Universität Marburg, D-35037 Marburg, Germany.
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Abstract
This review addresses classical questions concerning microvascular permeabiltiy in the light of recent experimental work on intact microvascular beds, single perfused microvessels, and endothelial cell cultures. Analyses, based on ultrastructural data from serial sections of the clefts between the endothelial cells of microvessels with continuous walls, conform to the hypothesis that different permeabilities to water and small hydrophilic solutes in microvessels of different tissues can be accounted for by tortuous three-dimensional pathways that pass through breaks in the junctional strands. A fiber matrix ultrafilter at the luminal entrance to the clefts is essential if microvascular walls are to retain their low permeability to macromolecules. Quantitative estimates of exchange through the channels in the endothelial cell membranes suggest that these contribute little to the permeability of most but not all microvessels. The arguments against the convective transport of macromolecules through porous pathways and for the passage of macromolecules by transcytosis via mechanisms linked to the integrity of endothelial vesicles are evaluated. Finally, intracellular signaling mechanisms implicated in transient increases in venular microvessel permeability such as occur in acute inflammation are reviewed in relation to studies of the molecular mechanisms involved in signal transduction in cultured endothelial cells.
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Affiliation(s)
- C C Michel
- Cellular and Integrative Biology, Division of Biomedical Sciences, Imperial College School of Medicine, London, United Kingdom
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Chen SC, Liu KM, Wagner RC. Three-dimensional analysis of vacuoles and surface invaginations of capillary endothelia in the eel rete mirabile. Anat Rec (Hoboken) 1998; 252:546-53. [PMID: 9845205 DOI: 10.1002/(sici)1097-0185(199812)252:4<546::aid-ar5>3.0.co;2-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
One layer of attenuated endothelia of continuous capillaries provides a partially selective diffusion barrier between the blood and the interstitium. Ultrastructures of membrane specialization without the known physiologic functions have been found in blood vessel endothelia. The vacuolar profiles or vacuole-like, membrane-bound structures, which are larger than plasmalemmal vesicles, have been observed routinely in normal endothelial cytoplasm or in blood vessels challenged by insults in electron microscopic studies. Three-dimensional information from serial sections is required to understand the organization and functions of vacuole-like structures in capillary endothelium. The capillaries in eel retia mirabile were perfused with electron-dense tracers, glutaraldehyde in buffer, and were processed for transmission electron microscopy. Ribbons of serial thin sections without counterstaining were examined under a transmission electron microscope. The vacuolar profiles inside endothelial cytoplasm were investigated with the techniques of serial section analysis and three-dimensional reconstruction from serial sections. The vacuole-like structures inside endothelial cytoplasm either were connected to extracellular (luminal, abluminal) compartments or existed as isolated vacuoles from serial section analysis. In the eight series examined in this study, six of ten vacuole-like structures were classified as isolated vacuoles inside endothelia, and their diameters ranged between 186 nm and 266 nm. Two of ten vacuole-like structures were found to extend to the luminal surface of capillaries as luminal, pocket-like invaginations. One of ten vacuole-like structures was found to be connected to the albuminal compartment, and another one existed as an extracellular compartment surrounded by endothelia. Three-dimensional projection of the vacuolar compartments from serial sections showed that endothelial cytoplasm of sheet shape protruded and folded over adjacent endothelium. Three-dimensional information from serial sections reveals the organization of vacuolar profiles and pocket-like invaginations from the cell surfaces in capillary endothelium. The vacuolar profiles in capillary endothelia in two-dimensional electron photomicrographs may represent the extracellular compartments surrounded by the endothelial finger-like extensions. The results indicate that the luminal and abluminal surfaces of the capillary lumen are not smooth or static, and endothelia may change their shape in three dimensions through cytoplasmic protrusions when the tissue environment changes.
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Affiliation(s)
- S C Chen
- Department of Anatomy, Kaohsiung Medical College, Taiwan, ROC.
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Bendayan M, Rasio EA. Evidence of a tubular system for transendothelial transport in arterial capillaries of the rete mirabile. J Histochem Cytochem 1997; 45:1365-78. [PMID: 9313798 DOI: 10.1177/002215549704501005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The arterial endothelial cells of the rete capillaries of the eel were examined by transmission electron microscopy on thin sections, on freeze-fracture replicas, by scanning electron microscopy, after cytochemical osmium impregnation and perfusion with peroxidase. The study revealed the existence of membrane-bound tubules and vesicles that open at both the luminal and abluminal poles of the cell and at the level of the intercellular space. The tubules are straight or present successive dilations and constrictions. They branch in various directions and intrude deeply into the cell cytoplasm, forming a complex tubular network within the cell. Immunocytochemical techniques were applied on immersion-fixed tissues and on perfusion of the capillaries with albumin and insulin. These demonstrated that the tubular-vesicular system is involved in the transport of circulating proteins. Furthermore, protein A-gold immunocytochemistry has revealed the association of actin with the membranes of this system. On the basis of these results, we suggest that the transendothelial transport of serum proteins takes place by a transcytotic process through a membrane-bound tubular-vesicular system and is equivalent to the large pore system presumed from functional studies.
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Affiliation(s)
- M Bendayan
- Department of Anatomy, Université de Montréal, Quebec, Canada
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