1
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Hongo H, Miyawaki S, Teranishi Y, Mitsui J, Katoh H, Komura D, Tsubota K, Matsukawa T, Watanabe M, Kurita M, Yoshimura J, Dofuku S, Ohara K, Ishigami D, Okano A, Kato M, Hakuno F, Takahashi A, Kunita A, Ishiura H, Shin M, Nakatomi H, Nagao T, Goto H, Takahashi SI, Ushiku T, Ishikawa S, Okazaki M, Morishita S, Tsuji S, Saito N. Somatic GJA4 gain-of-function mutation in orbital cavernous venous malformations. Angiogenesis 2023; 26:37-52. [PMID: 35902510 PMCID: PMC9908695 DOI: 10.1007/s10456-022-09846-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 06/23/2022] [Indexed: 12/25/2022]
Abstract
Orbital cavernous venous malformation (OCVM) is a sporadic vascular anomaly of uncertain etiology characterized by abnormally dilated vascular channels. Here, we identify a somatic missense mutation, c.121G > T (p.Gly41Cys) in GJA4, which encodes a transmembrane protein that is a component of gap junctions and hemichannels in the vascular system, in OCVM tissues from 25/26 (96.2%) individuals with OCVM. GJA4 expression was detected in OCVM tissue including endothelial cells and the stroma, through immunohistochemistry. Within OCVM tissue, the mutation allele frequency was higher in endothelial cell-enriched fractions obtained using magnetic-activated cell sorting. Whole-cell voltage clamp analysis in Xenopus oocytes revealed that GJA4 c.121G > T (p.Gly41Cys) is a gain-of-function mutation that leads to the formation of a hyperactive hemichannel. Overexpression of the mutant protein in human umbilical vein endothelial cells led to a loss of cellular integrity, which was rescued by carbenoxolone, a non-specific gap junction/hemichannel inhibitor. Our data suggest that GJA4 c.121G > T (p.Gly41Cys) is a potential driver gene mutation for OCVM. We propose that hyperactive hemichannel plays a role in the development of this vascular phenotype.
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Affiliation(s)
- Hiroki Hongo
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Satoru Miyawaki
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
| | - Yu Teranishi
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Jun Mitsui
- Department of Molecular Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hiroto Katoh
- Department of Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Daisuke Komura
- Department of Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kinya Tsubota
- Department of Ophthalmology, Tokyo Medical University, Tokyo, Japan
| | - Takashi Matsukawa
- Department of Molecular Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Masakatsu Watanabe
- Laboratory of Pattern Formation, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Masakazu Kurita
- Department of Plastic, Reconstructive and Aesthetic Surgery, The University of Tokyo Hospital, Tokyo, Japan
| | - Jun Yoshimura
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Shogo Dofuku
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Kenta Ohara
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Daiichiro Ishigami
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Atsushi Okano
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Motoi Kato
- Department of Plastic, Reconstructive and Aesthetic Surgery, The University of Tokyo Hospital, Tokyo, Japan
| | - Fumihiko Hakuno
- Department of Animal Resource Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Ayaka Takahashi
- Department of Animal Resource Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Akiko Kunita
- Department of Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hiroyuki Ishiura
- Department of Neurology, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Masahiro Shin
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Hirofumi Nakatomi
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Toshitaka Nagao
- Department of Anatomic Pathology, Tokyo Medical University, Tokyo, Japan
| | - Hiroshi Goto
- Department of Ophthalmology, Tokyo Medical University, Tokyo, Japan
| | - Shin-Ichiro Takahashi
- Department of Animal Resource Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Tetsuo Ushiku
- Department of Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Shumpei Ishikawa
- Department of Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Mutsumi Okazaki
- Department of Plastic, Reconstructive and Aesthetic Surgery, The University of Tokyo Hospital, Tokyo, Japan
| | - Shinichi Morishita
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Shoji Tsuji
- Department of Molecular Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Institute of Medical Genomics, International University of Health and Welfare, Narita, Chiba, Japan
| | - Nobuhito Saito
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
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2
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Fang JS, Burt JM. Connexin37 Regulates Cell Cycle in the Vasculature. J Vasc Res 2022; 60:73-86. [PMID: 36067749 DOI: 10.1159/000525619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/08/2022] [Indexed: 11/19/2022] Open
Abstract
Control of vascular cell growth responses is critical for development and maintenance of a healthy vasculature. Connexins - the proteins comprising gap junction channels - are key regulators of cell growth in diseases such as cancer, but their involvement in controlling cell growth in the vasculature is less well appreciated. Connexin37 (Cx37) is one of four connexin isotypes expressed in the vessel wall. Its primary role in blood vessels relies on its unique ability to transduce flow-sensitive signals into changes in cell cycle status of endothelial (and perhaps, mural) cells. Here, we review available evidence for Cx37's role in the regulation of vascular growth, vessel organization, and vascular tone in healthy and diseased vasculature. We propose a novel mechanism whereby Cx37 accomplishes this with a phosphorylation-dependent transition between closed (growth-suppressive) and multiple open (growth-permissive) channel conformations that result from interactions of the C-terminus with cell-cycle regulators to limit or support cell cycle progression. Lastly, we discuss Cx37 and its downstream signaling as a novel potential target in the treatment of cardiovascular disease, and we address outstanding research questions that still challenge the development of such therapies.
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Affiliation(s)
- Jennifer S Fang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana, USA
| | - Janis M Burt
- Department of Physiology, University of Arizona, Tucson, Arizona, USA
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3
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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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4
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Koepple C, Zhou Z, Huber L, Schulte M, Schmidt K, Gloe T, Kneser U, Schmidt VJ, de Wit C. Expression of Connexin43 Stimulates Endothelial Angiogenesis Independently of Gap Junctional Communication In Vitro. Int J Mol Sci 2021; 22:ijms22147400. [PMID: 34299018 PMCID: PMC8306600 DOI: 10.3390/ijms22147400] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/02/2021] [Accepted: 07/07/2021] [Indexed: 12/14/2022] Open
Abstract
Connexins (Cx) form gap junctions (GJ) and allow for intercellular communication. However, these proteins also modulate gene expression, growth, and cell migration. The downregulation of Cx43 impairs endothelial cell migration and angiogenetic potential. Conversely, endothelial Cx43 expression is upregulated in an in vivo angiogenesis model relying on hemodynamic forces. We studied the effects of Cx43 expression on tube formation and proliferation in HUVECs and examined its dependency on GJ communication. Expectedly, intercellular communication assessed by dye transfer was linked to Cx43 expression levels in HUVECs and was sensitive to a GJ blockade by the Cx43 mimetic peptide Gap27. The proliferation of HUVECs was not affected by Cx43 overexpression using Cx43 cDNA transfection, siRNA-mediated knockdown of Cx43, or the inhibition of GJ compared to the controls (transfection of an empty vector, scrambled siRNA, and the solvent). In contrast, endothelial tube and sprout formation in HUVECs was minimized after Cx43 knockdown and significantly enhanced after Cx43 overexpression. This was not affected by a GJ blockade (Gap27). We conclude that Cx43 expression positively modulates the angiogenic potential of endothelial cells independent of GJ communication. Since proliferation remained unaffected, we suggest that Cx43 protein may modulate endothelial cell migration, thereby supporting angiogenesis. The modulation of Cx43 expression may represent an exploitable principle for angiogenesis induction in clinical therapy.
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Affiliation(s)
- Christoph Koepple
- Department for Hand Surgery, Plastic Surgery and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Heidelberg University, 67071 Ludwigshafen, Germany; (Z.Z.); (L.H.); (M.S.); (U.K.)
- Correspondence: (C.K.); (V.J.S.); (C.d.W.)
| | - Zizi Zhou
- Department for Hand Surgery, Plastic Surgery and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Heidelberg University, 67071 Ludwigshafen, Germany; (Z.Z.); (L.H.); (M.S.); (U.K.)
| | - Lena Huber
- Department for Hand Surgery, Plastic Surgery and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Heidelberg University, 67071 Ludwigshafen, Germany; (Z.Z.); (L.H.); (M.S.); (U.K.)
| | - Matthias Schulte
- Department for Hand Surgery, Plastic Surgery and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Heidelberg University, 67071 Ludwigshafen, Germany; (Z.Z.); (L.H.); (M.S.); (U.K.)
| | - Kjestine Schmidt
- Institut für Physiologie, Universität zu Lübeck, 23562 Lübeck, Germany;
- Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), 23562 Lübeck, Germany
| | - Torsten Gloe
- Physiology, Institute of Theoretical Medicine, Universität Augsburg, 86159 Augsburg, Germany;
| | - Ulrich Kneser
- Department for Hand Surgery, Plastic Surgery and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Heidelberg University, 67071 Ludwigshafen, Germany; (Z.Z.); (L.H.); (M.S.); (U.K.)
| | - Volker Jürgen Schmidt
- Department for Plastic Surgery and Breast Surgery, Zealand University Hospital (SUH) Roskilde, Copenhagen University, 4000 Roskilde, Denmark
- Correspondence: (C.K.); (V.J.S.); (C.d.W.)
| | - Cor de Wit
- Institut für Physiologie, Universität zu Lübeck, 23562 Lübeck, Germany;
- Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), 23562 Lübeck, Germany
- Correspondence: (C.K.); (V.J.S.); (C.d.W.)
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5
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Abstract
Of the 21 members of the connexin family, 4 (Cx37, Cx40, Cx43, and Cx45) are expressed in the endothelium and/or smooth muscle of intact blood vessels to a variable and dynamically regulated degree. Full-length connexins oligomerize and form channel structures connecting the cytosol of adjacent cells (gap junctions) or the cytosol with the extracellular space (hemichannels). The different connexins vary mainly with regard to length and sequence of their cytosolic COOH-terminal tails. These COOH-terminal parts, which in the case of Cx43 are also translated as independent short isoforms, are involved in various cellular signaling cascades and regulate cell functions. This review focuses on channel-dependent and -independent effects of connexins in vascular cells. Channels play an essential role in coordinating and synchronizing endothelial and smooth muscle activity and in their interplay, in the control of vasomotor actions of blood vessels including endothelial cell reactivity to agonist stimulation, nitric oxide-dependent dilation, and endothelial-derived hyperpolarizing factor-type responses. Further channel-dependent and -independent roles of connexins in blood vessel function range from basic processes of vascular remodeling and angiogenesis to vascular permeability and interactions with leukocytes with the vessel wall. Together, these connexin functions constitute an often underestimated basis for the enormous plasticity of vascular morphology and function enabling the required dynamic adaptation of the vascular system to varying tissue demands.
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Affiliation(s)
- Ulrich Pohl
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Planegg-Martinsried, Germany; Biomedical Centre, Cardiovascular Physiology, LMU Munich, Planegg-Martinsried, Germany; German Centre for Cardiovascular Research, Partner Site Munich Heart Alliance, Munich, Germany; and Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
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6
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Rozas-Villanueva MF, Casanello P, Retamal MA. Role of ROS/RNS in Preeclampsia: Are Connexins the Missing Piece? Int J Mol Sci 2020; 21:ijms21134698. [PMID: 32630161 PMCID: PMC7369723 DOI: 10.3390/ijms21134698] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 06/18/2020] [Accepted: 06/28/2020] [Indexed: 12/15/2022] Open
Abstract
Preeclampsia is a pregnancy complication that appears after 20 weeks of gestation and is characterized by hypertension and proteinuria, affecting both mother and offspring. The cellular and molecular mechanisms that cause the development of preeclampsia are poorly understood. An important feature of preeclampsia is an increase in oxygen and nitrogen derived free radicals (reactive oxygen species/reactive nitrogen species (ROS/RNS), which seem to be central players setting the development and progression of preeclampsia. Cell-to-cell communication may be disrupted as well. Connexins (Cxs), a family of transmembrane proteins that form hemichannels and gap junction channels (GJCs), are essential in paracrine and autocrine cell communication, allowing the movement of signaling molecules between cells as well as between the cytoplasm and the extracellular media. GJCs and hemichannels are fundamental for communication between endothelial and smooth muscle cells and, therefore, in the control of vascular contraction and relaxation. In systemic vasculature, the activity of GJCs and hemichannels is modulated by ROS and RNS. Cxs participate in the development of the placenta and are expressed in placental vasculature. However, it is unknown whether Cxs are modulated by ROS/RNS in the placenta, or whether this potential modulation contributes to the pathogenesis of preeclampsia. Our review addresses the possible role of Cxs in preeclampsia, and the plausible modulation of Cxs-formed channels by ROS and RNS. We suggest these factors may contribute to the development of preeclampsia.
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Affiliation(s)
- María F. Rozas-Villanueva
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago 7690000, Chile;
- Programa de Doctorado en Ciencias e Innovación en Medicina, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago 7690000, Chile
| | - Paola Casanello
- Department of Obstetrics, School of Medicine, Pontificia Universidad Católica de Chile, Santiago 7690000, Chile;
- Department of Neonatology, School of Medicine, Pontificia Universidad Católica de Chile, Santiago 7690000, Chile
| | - Mauricio A. Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago 7690000, Chile;
- Programa de Comunicación Celular de Cáncer, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago 7690000, Chile
- Correspondence:
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7
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Wu X, Zhang W, Li Y, Lin X. Structure and Function of Cochlear Gap Junctions and Implications for the Translation of Cochlear Gene Therapies. Front Cell Neurosci 2019; 13:529. [PMID: 31827424 PMCID: PMC6892400 DOI: 10.3389/fncel.2019.00529] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 11/13/2019] [Indexed: 12/23/2022] Open
Abstract
Connexins (Cxs) are ubiquitous membrane proteins that are found throughout vertebrate organs, acting as building blocks of the gap junctions (GJs) known to play vital roles in the normal function of many organs. Mutations in Cx genes (particularly GJB2, which encodes Cx26) cause approximately half of all cases of congenital hearing loss in newborns. Great progress has been made in understanding GJ function and the molecular mechanisms for the role of Cxs in the cochlea. Data reveal that multiple types of Cxs work together to ensure normal development and function of the cochlea. These findings include many aspects not proposed in the classic K+ recycling theory, such as the formation of normal cochlear morphology (e.g., the opening of the tunnel of Corti), the fine-tuning of the innervation of nerve fibers to the hair cells (HCs), the maturation of the ribbon synapses, and the initiation of the endocochlear potential (EP). New data, especially those collected from targeted modification of major Cx genes in the mouse cochlea, have demonstrated that Cx26 plays an essential role in the postnatal maturation of the cochlea. Studies also show that Cx26 and Cx30 assume very different roles in the EP generation, given that only Cx26 is required for normal hearing. This article will review our current understanding of the molecular structure, cellular distribution, and major functions of cochlear GJs. Potential implications of the knowledge of cochlear GJs on the design and implementation of translational studies of cochlear gene therapies for Cx mutations are also discussed.
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Affiliation(s)
- Xuewen Wu
- Department of Otolaryngology, Head-Neck and Surgery, Xiangya Hospital of Central South University, Changsha, China
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
| | - Wenjuan Zhang
- Department of Otolaryngology, Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yihui Li
- Department of Pharmacy, Changsha Hospital of Traditional Medicine, Changsha, China
| | - Xi Lin
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
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8
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Pogoda K, Kameritsch P, Mannell H, Pohl U. Connexins in the control of vasomotor function. Acta Physiol (Oxf) 2019; 225:e13108. [PMID: 29858558 DOI: 10.1111/apha.13108] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 05/25/2018] [Accepted: 05/28/2018] [Indexed: 12/13/2022]
Abstract
Vascular endothelial cells, as well as smooth muscle cells, show heterogeneity with regard to their receptor expression and reactivity. For the vascular wall to act as a functional unit, the various cells' responses require integration. Such an integration is not only required for a homogeneous response of the vascular wall, but also for the vasomotor behaviour of consecutive segments of the microvascular arteriolar tree. As flow resistances of individual sections are connected in series, sections require synchronization and coordination to allow effective changes of conductivity and blood flow. A prerequisite for the local coordination of individual vascular cells and different sections of an arteriolar tree is intercellular communication. Connexins are involved in a dual manner in this coordination. (i) By forming gap junctions between cells, they allow an intercellular exchange of signalling molecules and electrical currents. In particular, the spread of electrical currents allows for coordination of cell responses over longer distances. (ii) Connexins are able to interact with other proteins to form signalling complexes. In this way, they can modulate and integrate individual cells' responses also in a channel-independent manner. This review outlines mechanisms allowing the vascular connexins to exert their coordinating function and to regulate the vasomotor reactions of blood vessels both locally, and in vascular networks. Wherever possible, we focus on the vasomotor behaviour of small vessels and arterioles which are the main vessels determining vascular resistance, blood pressure and local blood flow.
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Affiliation(s)
- K. Pogoda
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
- DZHK (German Center for Cardiovascular Research); Partner Site Munich Heart Alliance; Munich Germany
| | - P. Kameritsch
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
- DZHK (German Center for Cardiovascular Research); Partner Site Munich Heart Alliance; Munich Germany
| | - H. Mannell
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
| | - U. Pohl
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
- DZHK (German Center for Cardiovascular Research); Partner Site Munich Heart Alliance; Munich Germany
- Munich Cluster for Systems Neurology (SyNergy); Munich Germany
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9
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Htet M, Nally JE, Shaw A, Foote BE, Martin PE, Dempsie Y. Connexin 43 Plays a Role in Pulmonary Vascular Reactivity in Mice. Int J Mol Sci 2018; 19:E1891. [PMID: 29954114 PMCID: PMC6073802 DOI: 10.3390/ijms19071891] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/07/2018] [Accepted: 06/20/2018] [Indexed: 11/25/2022] Open
Abstract
Pulmonary arterial hypertension (PAH) is a chronic condition characterized by vascular remodeling and increased vaso-reactivity. PAH is more common in females than in males (~3:1). Connexin (Cx)43 has been shown to be involved in cellular communication within the pulmonary vasculature. Therefore, we investigated the role of Cx43 in pulmonary vascular reactivity using Cx43 heterozygous (Cx43+/−) mice and 37,43Gap27, which is a pharmacological inhibitor of Cx37 and Cx43. Contraction and relaxation responses were studied in intra-lobar pulmonary arteries (IPAs) derived from normoxic mice and hypoxic mice using wire myography. IPAs from male Cx43+/− mice displayed a small but significant increase in the contractile response to endothelin-1 (but not 5-hydroxytryptamine) under both normoxic and hypoxic conditions. There was no difference in the contractile response to endothelin-1 (ET-1) or 5-hydroxytryptamine (5-HT) in IPAs derived from female Cx43+/−mice compared to wildtype mice. Relaxation responses to methacholine (MCh) were attenuated in IPAs from male and female Cx43+/− mice or by pre-incubation of IPAs with 37,43Gap27. Nω-Nitro-L-arginine methyl ester (l-NAME) fully inhibited MCh-induced relaxation. In conclusion, Cx43 is involved in nitric oxide (NO)-induced pulmonary vascular relaxation and plays a gender-specific and agonist-specific role in pulmonary vascular contractility. Therefore, reduced Cx43 signaling may contribute to pulmonary vascular dysfunction.
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Affiliation(s)
- Myo Htet
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Jane E Nally
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Andrew Shaw
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Bradley E Foote
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Patricia E Martin
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Yvonne Dempsie
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
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10
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Ortiz-Escribano N, Szymanska KJ, Bol M, Vandenberghe L, Decrock E, Van Poucke M, Peelman L, Van den Abbeel E, Van Soom A, Leybaert L. Blocking connexin channels improves embryo development of vitrified bovine blastocysts. Biol Reprod 2018; 96:288-301. [PMID: 28203704 DOI: 10.1095/biolreprod.116.144121] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 12/01/2016] [Accepted: 01/03/2017] [Indexed: 01/13/2023] Open
Abstract
Connexins (Cxs) are required for normal embryo development and implantation. They form gap junctions (GJs) connecting the cytoplasm of adjacent cells and hemichannels (HCs), which are normally closed but open in response to stress conditions. Excessive HC opening is detrimental for cell function and may lead to cell death. We found that hatching of in vitro-produced bovine embryos, matured in serum-containing conditions, was significantly improved when vitrification/warming was done in the presence of Gap26 that targets GJA1 (Cx43) and GJA4 (Cx37). Further work showed that HCs from blastocysts produced after oocyte maturation in the presence of serum were open shortly after vitrification/warming, and this was prevented by Gap26. Gap26, applied for the exposure times used, inhibited Cx43 and Cx37 HCs while it did not have an effect on GJs. Interestingly, Gap26 had no effect on blastocyst degeneration or cell death. We conclude that blocking HCs protects embryos during vitrification and warming by a functional effect not linked to cell death.
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Affiliation(s)
| | | | - Melissa Bol
- Physiology group, Department of Basic Medical Sciences, Ghent University, Ghent, Belgium
| | - Lynn Vandenberghe
- Reproduction, Obstetrics and Herd Health, Ghent University, Merelbeke, Belgium
| | - Elke Decrock
- Physiology group, Department of Basic Medical Sciences, Ghent University, Ghent, Belgium
| | - Mario Van Poucke
- Department of Nutrition, Genetics and Ethology, Ghent University, Merelbeke, Belgium
| | - Luc Peelman
- Department of Nutrition, Genetics and Ethology, Ghent University, Merelbeke, Belgium
| | | | - Ann Van Soom
- Reproduction, Obstetrics and Herd Health, Ghent University, Merelbeke, Belgium
| | - Luc Leybaert
- Physiology group, Department of Basic Medical Sciences, Ghent University, Ghent, Belgium
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Redox-mediated regulation of connexin proteins; focus on nitric oxide. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:91-95. [DOI: 10.1016/j.bbamem.2017.10.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 08/25/2017] [Accepted: 10/06/2017] [Indexed: 12/14/2022]
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Pogoda K, Mannell H, Blodow S, Schneider H, Schubert KM, Qiu J, Schmidt A, Imhof A, Beck H, Tanase LI, Pfeifer A, Pohl U, Kameritsch P. NO Augments Endothelial Reactivity by Reducing Myoendothelial Calcium Signal Spreading: A Novel Role for Cx37 (Connexin 37) and the Protein Tyrosine Phosphatase SHP-2. Arterioscler Thromb Vasc Biol 2017; 37:2280-2290. [PMID: 29025706 DOI: 10.1161/atvbaha.117.309913] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 09/26/2017] [Indexed: 01/31/2023]
Abstract
OBJECTIVE Because of its strategic position between endothelial and smooth muscle cells in microvessels, Cx37 (Connexin 37) plays an important role in myoendothelial gap junctional intercellular communication. We have shown before that NO inhibits gap junctional intercellular communication through gap junctions containing Cx37. However, the underlying mechanism is not yet identified. APPROACH AND RESULTS Using channel-forming Cx37 mutants exhibiting partial deletions or amino acid exchanges in their C-terminal loops, we now show that the phosphorylation state of a tyrosine residue at position 332 (Y332) in the C-terminus of Cx37 controls the gap junction-dependent spread of calcium signals. Mass spectra revealed that NO protects Cx37 from dephosphorylation at Y332 by inhibition of the protein tyrosine phosphatase SHP-2. Functionally, the inhibition of gap junctional intercellular communication by NO decreased the spread of the calcium signal (induced by mechanical stimulation of individual endothelial cells) from endothelial to smooth muscle cells in intact vessels, while, at the same time, augmenting the calcium signal spreading within the endothelium. Consequently, preincubation of small resistance arteries with exogenous NO enhanced the endothelium-dependent dilator response to acetylcholine in spite of a pharmacological blockade of NO-dependent cGMP formation by the soluable guanylyl cyclase inhibitor ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one). CONCLUSIONS Our results identify a novel mechanism by which NO can increase the efficacy of calcium, rising vasoactive agonists in the microvascular endothelium.
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Affiliation(s)
- Kristin Pogoda
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.)
| | - Hanna Mannell
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.)
| | - Stephanie Blodow
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.)
| | - Holger Schneider
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.)
| | - Kai Michael Schubert
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.)
| | - Jiehua Qiu
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.)
| | - Andreas Schmidt
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.)
| | - Axel Imhof
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.)
| | - Heike Beck
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.)
| | - Laurentia Irina Tanase
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.)
| | - Alexander Pfeifer
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.)
| | - Ulrich Pohl
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.).
| | - Petra Kameritsch
- From the Walter Brendel Centre of Experimental Medicine, University Hospital, Biomedical Center, Munich, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., L.I.T., U.P., P.K.); Protein Analysis Unit, Biomedical Center, Munich, Germany (A.S., A.I.); DZHK (German Center for Cardiovascular Research), partner site Munich Heart Alliance, Germany (K.P., H.M., S.B., H.S., K.M.S., J.Q., H.B., U.P., P.K.); Munich Cluster for Systems Neurology (SyNergY), Germany (A.I., U.P.); and Institute of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany (A.P.)
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Ampey BC, Morschauser TJ, Ramadoss J, Magness RR. Domain-Specific Partitioning of Uterine Artery Endothelial Connexin43 and Caveolin-1. Hypertension 2016; 68:982-8. [PMID: 27572151 DOI: 10.1161/hypertensionaha.116.08000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 08/01/2016] [Indexed: 11/16/2022]
Abstract
Uterine vascular adaptations facilitate rises in uterine blood flow during pregnancy, which are associated with gap junction connexin (Cx) proteins and endothelial nitric oxide synthase. In uterine artery endothelial cells (UAECs), ATP activates endothelial nitric oxide synthase in a pregnancy (P)-specific manner that is dependent on Cx43 function. Caveolar subcellular domain partitioning plays key roles in ATP-induced endothelial nitric oxide synthase activation and nitric oxide production. Little is known regarding the partitioning of Cx proteins to caveolar domains or their dynamics with ATP treatment. We observed that Cx43-mediated gap junction function with ATP stimulation is associated with Cx43 repartitioning between the noncaveolar and caveolar domains. Compared with UAECs from nonpregnant (NP) ewes, levels of ATP, PGI2, cAMP, NOx, and cGMP were 2-fold higher (P<0.05) in pregnant UAECs. In pregnant UAECs, ATP increased Lucifer yellow dye transfer, a response abrogated by Gap27, but not Gap 26, indicating involvement of Cx43, but not Cx37. Confocal microscopy revealed domain partitioning of Cx43 and caveolin-1. In pregnant UAECs, LC/MS/MS analysis revealed only Cx43 in the caveolar domain. In contrast, Cx37 was located only in the noncaveolar pool. Western analysis revealed that ATP increased Cx43 distribution (1.7-fold; P=0.013) to the caveolar domain, but had no effect on Cx37. These data demonstrate rapid ATP-stimulated repartitioning of Cx43 to the caveolae, where endothelial nitric oxide synthase resides and plays an important role in nitric oxide-mediated increasing uterine blood flow during pregnancy.
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Affiliation(s)
- Bryan C Ampey
- From the Department of Ob/Gyn, University of Wisconsin, Madison (B.C.A., T.J.M., R.R.M.); Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station (J.R.); and Department of Ob/Gyn, University South Florida, Perinatal Research Center Tampa (R.R.M.)
| | - Timothy J Morschauser
- From the Department of Ob/Gyn, University of Wisconsin, Madison (B.C.A., T.J.M., R.R.M.); Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station (J.R.); and Department of Ob/Gyn, University South Florida, Perinatal Research Center Tampa (R.R.M.)
| | - Jayanth Ramadoss
- From the Department of Ob/Gyn, University of Wisconsin, Madison (B.C.A., T.J.M., R.R.M.); Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station (J.R.); and Department of Ob/Gyn, University South Florida, Perinatal Research Center Tampa (R.R.M.)
| | - Ronald R Magness
- From the Department of Ob/Gyn, University of Wisconsin, Madison (B.C.A., T.J.M., R.R.M.); Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station (J.R.); and Department of Ob/Gyn, University South Florida, Perinatal Research Center Tampa (R.R.M.).
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14
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Pogoda K, Kameritsch P, Retamal MA, Vega JL. Regulation of gap junction channels and hemichannels by phosphorylation and redox changes: a revision. BMC Cell Biol 2016; 17 Suppl 1:11. [PMID: 27229925 PMCID: PMC4896245 DOI: 10.1186/s12860-016-0099-3] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Post-translational modifications of connexins play an important role in the regulation of gap junction and hemichannel permeability. The prerequisite for the formation of functional gap junction channels is the assembly of connexin proteins into hemichannels and their insertion into the membrane. Hemichannels can affect cellular processes by enabling the passage of signaling molecules between the intracellular and extracellular space. For the intercellular communication hemichannels from one cell have to dock to its counterparts on the opposing membrane of an adjacent cell to allow the transmission of signals via gap junctions from one cell to the other. The controlled opening of hemichannels and gating properties of complete gap junctions can be regulated via post-translational modifications of connexins. Not only channel gating, but also connexin trafficking and assembly into hemichannels can be affected by post-translational changes. Recent investigations have shown that connexins can be modified by phosphorylation/dephosphorylation, redox-related changes including effects of nitric oxide (NO), hydrogen sulfide (H2S) or carbon monoxide (CO), acetylation, methylation or ubiquitination. Most of the connexin isoforms are known to be phosphorylated, e.g. Cx43, one of the most studied connexin at all, has 21 reported phosphorylation sites. In this review, we provide an overview about the current knowledge and relevant research of responsible kinases, connexin phosphorylation sites and reported effects on gap junction and hemichannel regulation. Regarding the effects of oxidants we discuss the role of NO in different cell types and tissues and recent studies about modifications of connexins by CO and H2S.
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Affiliation(s)
- Kristin Pogoda
- Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München and Munich University Hospital, München, Germany. .,DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, München, Germany.
| | - Petra Kameritsch
- Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München and Munich University Hospital, München, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, München, Germany
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - José L Vega
- Experimental Physiology Laboratory (EPhyL), Antofagasta Institute, Universidad de Antofagasta, Antofagasta, Chile
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15
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Dong L, Yang X, Gu W, Zhao K, Ge H, Zhou J, Bai X. Connexin 43 mediates PFOS-induced apoptosis in astrocytes. CHEMOSPHERE 2015; 132:8-16. [PMID: 25770831 DOI: 10.1016/j.chemosphere.2015.02.041] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Revised: 02/17/2015] [Accepted: 02/18/2015] [Indexed: 06/04/2023]
Abstract
Perfluorooctane sulfonate (PFOS) is a man-made environmental pollutant that is toxic to mammals. However, the neurotoxic effects of PFOS remain largely unexplored. In this study, we determined the role of an astrocyte specific gap junction protein, connexin 43 (Cx43), in PFOS-induced apoptosis. The rate of astrocyte apoptosis was higher in cortex astrocytes after PFOS treatment. These astrocytes also showed up-regulated expression of Cx43 and higher levels of cleaved caspase-3. Elevated ROS accumulation and decreased ΔΨm also confirmed the presence of PFOS-induced apoptosis. However, the exposure of astrocytes to PFOS together with carbenoxolone (CBX) significantly reduced both Cx43 and cleaved caspase-3 levels. These results indicate that Cx43 plays a proapoptotic role in PFOS-induced apoptosis in cortex astrocyte cells.
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Affiliation(s)
- Li Dong
- Institute for Environmental Health and Related Product Safety, Chinese Center for Disease Control and Prevention, 7 Panjiayuan Nanli Road, Chaoyang District, Beijing 100021, China.
| | - Xiaoyan Yang
- Institute for Environmental Health and Related Product Safety, Chinese Center for Disease Control and Prevention, 7 Panjiayuan Nanli Road, Chaoyang District, Beijing 100021, China
| | - Wen Gu
- Institute for Environmental Health and Related Product Safety, Chinese Center for Disease Control and Prevention, 7 Panjiayuan Nanli Road, Chaoyang District, Beijing 100021, China
| | - Kangfeng Zhao
- Institute for Environmental Health and Related Product Safety, Chinese Center for Disease Control and Prevention, 7 Panjiayuan Nanli Road, Chaoyang District, Beijing 100021, China
| | - Huizheng Ge
- Beijing Biodonor Biotech Ltd., 88 The 6th Kechuang Street, Incubation Center Room 303, 101111 Beijing, China
| | - Jianjun Zhou
- Beijing Biodonor Biotech Ltd., 88 The 6th Kechuang Street, Incubation Center Room 303, 101111 Beijing, China
| | - Xuetao Bai
- Institute for Environmental Health and Related Product Safety, Chinese Center for Disease Control and Prevention, 7 Panjiayuan Nanli Road, Chaoyang District, Beijing 100021, China.
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Muto T, Tien T, Kim D, Sarthy VP, Roy S. High glucose alters Cx43 expression and gap junction intercellular communication in retinal Müller cells: promotes Müller cell and pericyte apoptosis. Invest Ophthalmol Vis Sci 2014; 55:4327-37. [PMID: 24938518 DOI: 10.1167/iovs.14-14606] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
PURPOSE To investigate whether high glucose (HG) alters connexin 43 (Cx43) expression and gap junction intercellular communication (GJIC) activity in retinal Müller cells, and promotes Müller cell and pericyte loss. METHODS Retinal Müller cells (rMC-1) and cocultures of rMC-1 and retinal pericytes were grown in normal (N) or HG (30 mM glucose) medium. Additionally, rMC-1 transfected with Cx43 small interfering RNA (siRNA) were grown as cocultures with pericytes, and rMC-1 transfected with Cx43 plasmid were grown in HG. Expression of Cx43 was determined by Western blotting and immunostaining and GJIC was assessed by scrape-loading dye transfer (SLDT) technique. Apoptosis was analyzed by TUNEL or differential staining assay, and Akt activation by assessing Akt phosphorylation. RESULTS In monocultures of rMC-1 and cocultures of rMC-1 and pericytes, Cx43 protein level, number of Cx43 plaques, GJIC, and Akt phosphorylation were significantly reduced in HG medium. Number of TUNEL-positive cells was also significantly increased in rMC-1 monocultures and in rMC-1 and pericyte cocultures grown in HG medium. Importantly, when rMC-1 transfected with Cx43 siRNA were grown as cocultures with pericytes, a significant decrease in GJIC, and increase in TUNEL-positive cells was observed, concomitant with decreased Akt phosphorylation. Upregulation of Cx43 rescued rMC-1 from HG-induced apoptosis. CONCLUSIONS Gap junction communication between Müller cells and pericytes is essential for their survival. Downregulation of Cx43 that is HG induced and impairment of GJIC activity in Müller cells contributes to loss of glial and vascular cells associated with the pathogenesis of diabetic retinopathy.
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Affiliation(s)
- Tetsuya Muto
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Thomas Tien
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Dongjoon Kim
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Vijay P Sarthy
- Department of Ophthalmology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States
| | - Sayon Roy
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
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Pogoda K, Füller M, Pohl U, Kameritsch P. NO, via its target Cx37, modulates calcium signal propagation selectively at myoendothelial gap junctions. Cell Commun Signal 2014; 12:33. [PMID: 24885166 PMCID: PMC4036488 DOI: 10.1186/1478-811x-12-33] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 05/03/2014] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Gap junctional calcium signal propagation (transfer of calcium or a calcium releasing messenger via gap junctions) between vascular cells has been shown to be involved in the control of vascular tone. We have shown before that nitric oxide (NO) inhibits gap junctional communication in HeLa cells exclusively expressing connexin 37 (HeLa-Cx37) but not in HeLa-Cx40 or HeLa-Cx43. Here we studied the effect of NO on the gap junctional calcium signal propagation in endothelial cells which, in addition to Cx37, also express Cx40 and Cx43. Furthermore, we analyzed the impact of NO on intermuscle and on myoendothelial gap junction-dependent calcium signal propagation. Since specific effects of NO at one of these three junctional areas (interendothelial/ myoendothelial/ intermuscle) may depend on a differential membrane localization of the connexins, we also studied the distribution of the vascular connexins in small resistance arteries. RESULTS In endothelial (HUVEC) or smooth muscle cells (HUVSMC) alone, NO did not affect gap junctional Ca2+ signal propagation as assessed by analyzing the spread of Ca2+ signals after mechanical stimulation of a single cell. In contrast, at myoendothelial junctions, it decreased Ca2+ signal propagation in both directions by about 60% (co-cultures of HUVEC and HUVSMC). This resulted in a longer maintenance of calcium elevation at the endothelial side and a faster calcium signal propagation at the smooth muscle side, respectively. Immunohistochemical stainings (confocal and two-photon-microscopy) of cells in co-cultures or of small arteries revealed that Cx37 expression was relatively higher in endothelial cells adjoining smooth muscle (culture) or in potential areas of myoendothelial junctions (arteries). Accordingly, Cx37 - in contrast to Cx40 - was not only expressed on the endothelial surface of small arteries but also in deeper layers (corresponding to the internal elastic lamina IEL). Holes of the IEL where myoendothelial contacts can only occur, stained significantly more frequently for Cx37 and Cx43 than for Cx40 (endothelium) or Cx45 (smooth muscle). CONCLUSION NO modulates the calcium signal propagation specifically between endothelial and smooth muscle cells. The effect is due to an augmented distribution of Cx37 towards myoendothelial contact areas and potentially counteracts endothelial Ca2+ signal loss from endothelial to smooth muscle cells. This targeted effect of NO may optimize calcium dependent endothelial vasomotor function.
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Affiliation(s)
- Kristin Pogoda
- Walter Brendel Centre of Experimental Medicine, Munich Heart Alliance, Ludwig-Maximilians-Universität München, Munich, Germany
- DZHK (German Centre of Cardiovascular Research), partner site Munich Heart Alliance, Marchioninistr. 27, 81377 Munich, Germany
| | - Monika Füller
- Walter Brendel Centre of Experimental Medicine, Munich Heart Alliance, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Ulrich Pohl
- Walter Brendel Centre of Experimental Medicine, Munich Heart Alliance, Ludwig-Maximilians-Universität München, Munich, Germany
- DZHK (German Centre of Cardiovascular Research), partner site Munich Heart Alliance, Marchioninistr. 27, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergY), Munich, Germany
| | - Petra Kameritsch
- Walter Brendel Centre of Experimental Medicine, Munich Heart Alliance, Ludwig-Maximilians-Universität München, Munich, Germany
- DZHK (German Centre of Cardiovascular Research), partner site Munich Heart Alliance, Marchioninistr. 27, 81377 Munich, Germany
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Feher A, Broskova Z, Bagi Z. Age-related impairment of conducted dilation in human coronary arterioles. Am J Physiol Heart Circ Physiol 2014; 306:H1595-601. [PMID: 24778172 DOI: 10.1152/ajpheart.00179.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Conducted vasodilation is essential to coordinate vascular resistance along distances to ensure adequate tissue perfusion. We hypothesized that conducted vasodilation of coronary resistance arteries declines with age. Coronary arterioles were dissected from right atrial appendage of patients (n = 27) undergoing cardiac surgery. Arterioles (~100 μm) were cannulated and pressurized (80 mmHg), and developed spontaneous myogenic tone. Conducted vasodilation was initiated by locally administering the endothelium-dependent agonist bradykinin (BK; 100 μM) ejected from a glass micropipette (~3 μm tip opening, positioned in close proximity to the vessel wall). Diameter changes were measured at local and upstream sites (500 and 1,000 μm from the stimulus) with videomicroscopy. Local administration of BK elicited vasodilation, the magnitude of which increased with the duration of stimulus (69 ± 6, 81 ± 6, 90 ± 2%, after 1, 3, and 5 × 100 ms, respectively). BK-induced dilation remained substantial at upstream sites (500 μm: 53 ± 7%; 1,000 μm: 46 ± 9%). The gap junction uncoupler carbenoxolone or 18-α-glycyrrhetinic acid did not affect local responses, but diminished conducted vasodilation. Inhibitors of small/intermediate conductance calcium-activated potassium channels (SKCa/IKCa), apamin and TRAM34, reduced dilations both at local and remote sites. We found that conducted dilation, but not the local response, was significantly reduced in older (≥64 yr) patients. The nitric oxide (NO) synthesis inhibitor N(ω)-nitro-l-arginine methyl ester did not affect local responses, but markedly reduced conducted dilation in younger (<64 yr) individuals. Collectively, we show that human coronary arterioles exhibit SKCa/IKCa-mediated hyperpolarization spread through gap junctions, which contributes to conducted vasodilation initiated by focal application of BK. We demonstrate that conducted dilation declines with age, likely due to reduced NO availability, which plays a permissive role in propagating longitudinal vasomotor signaling.
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Affiliation(s)
- Attila Feher
- Vascular Biology Center, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
| | - Zuzana Broskova
- Vascular Biology Center, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
| | - Zsolt Bagi
- Vascular Biology Center, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
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19
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Billaud M, Lohman AW, Johnstone SR, Biwer LA, Mutchler S, Isakson BE. Regulation of cellular communication by signaling microdomains in the blood vessel wall. Pharmacol Rev 2014; 66:513-69. [PMID: 24671377 DOI: 10.1124/pr.112.007351] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
It has become increasingly clear that the accumulation of proteins in specific regions of the plasma membrane can facilitate cellular communication. These regions, termed signaling microdomains, are found throughout the blood vessel wall where cellular communication, both within and between cell types, must be tightly regulated to maintain proper vascular function. We will define a cellular signaling microdomain and apply this definition to the plethora of means by which cellular communication has been hypothesized to occur in the blood vessel wall. To that end, we make a case for three broad areas of cellular communication where signaling microdomains could play an important role: 1) paracrine release of free radicals and gaseous molecules such as nitric oxide and reactive oxygen species; 2) role of ion channels including gap junctions and potassium channels, especially those associated with the endothelium-derived hyperpolarization mediated signaling, and lastly, 3) mechanism of exocytosis that has considerable oversight by signaling microdomains, especially those associated with the release of von Willebrand factor. When summed, we believe that it is clear that the organization and regulation of signaling microdomains is an essential component to vessel wall function.
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Affiliation(s)
- Marie Billaud
- Dept. of Molecular Physiology and Biophysics, University of Virginia School of Medicine, PO Box 801394, Charlottesville, VA 22902.
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20
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Axelsen LN, Calloe K, Holstein-Rathlou NH, Nielsen MS. Managing the complexity of communication: regulation of gap junctions by post-translational modification. Front Pharmacol 2013; 4:130. [PMID: 24155720 PMCID: PMC3804956 DOI: 10.3389/fphar.2013.00130] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 09/30/2013] [Indexed: 12/21/2022] Open
Abstract
Gap junctions are comprised of connexins that form cell-to-cell channels which couple neighboring cells to accommodate the exchange of information. The need for communication does, however, change over time and therefore must be tightly controlled. Although the regulation of connexin protein expression by transcription and translation is of great importance, the trafficking, channel activity and degradation are also under tight control. The function of connexins can be regulated by several post translational modifications, which affect numerous parameters; including number of channels, open probability, single channel conductance or selectivity. The most extensively investigated post translational modifications are phosphorylations, which have been documented in all mammalian connexins. Besides phosphorylations, some connexins are known to be ubiquitinated, SUMOylated, nitrosylated, hydroxylated, acetylated, methylated, and γ-carboxyglutamated. The aim of the present review is to summarize our current knowledge of post translational regulation of the connexin family of proteins.
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Affiliation(s)
- Lene N Axelsen
- Department of Biomedical Sciences and The Danish National Research Foundation Centre for Cardiac Arrhythmia, Faculty of Health and Medical Sciences, University of Copenhagen Copenhagen, Denmark
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21
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D'hondt C, Iyyathurai J, Vinken M, Rogiers V, Leybaert L, Himpens B, Bultynck G. Regulation of connexin- and pannexin-based channels by post-translational modifications. Biol Cell 2013; 105:373-98. [PMID: 23718186 DOI: 10.1111/boc.201200096] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 05/24/2013] [Indexed: 12/28/2022]
Abstract
Connexin (Cx) and pannexin (Panx) proteins form large conductance channels, which function as regulators of communication between neighbouring cells via gap junctions and/or hemichannels. Intercellular communication is essential to coordinate cellular responses in tissues and organs, thereby fulfilling an essential role in the spreading of signalling, survival and death processes. The functional properties of gap junctions and hemichannels are modulated by different physiological and pathophysiological stimuli. At the molecular level, Cxs and Panxs function as multi-protein channel complexes, regulating their channel localisation and activity. In addition to this, gap junctional channels and hemichannels are modulated by different post-translational modifications (PTMs), including phosphorylation, glycosylation, proteolysis, N-acetylation, S-nitrosylation, ubiquitination, lipidation, hydroxylation, methylation and deamidation. These PTMs influence almost all aspects of communicating junctional channels in normal cell biology and pathophysiology. In this review, we will provide a systematic overview of PTMs of communicating junction proteins and discuss their effects on Cx and Panx-channel activity and localisation.
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Affiliation(s)
- Catheleyne D'hondt
- Laboratory of Molecular and Cellular Signalling, Department Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O/N 1, BE-3000, Leuven, Belgium.
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22
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Kameritsch P, Khandoga N, Pohl U, Pogoda K. Gap junctional communication promotes apoptosis in a connexin-type-dependent manner. Cell Death Dis 2013; 4:e584. [PMID: 23579271 PMCID: PMC3641328 DOI: 10.1038/cddis.2013.105] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 01/31/2013] [Accepted: 02/21/2013] [Indexed: 12/28/2022]
Abstract
Gap junctions (GJs) have been described to modulate cell death and survival. It still remains unclear whether this effect requires functional GJ channels or depends on channel-independent effects of connexins (Cx), the constituents of GJs. Therefore, we analysed the apoptotic response to streptonigrin (SN, intrinsic apoptotic pathway) or to α-Fas (extrinsic apoptotic pathway) in HeLa cells expressing Cx43 as compared with empty vector-transfected (CTL) cells. Apoptosis assessed by annexin V-fluorescein isothiocyanate/propidium iodide staining was significantly higher in HeLa-Cx43 compared with HeLa-CTL cells. Moreover, the cleavage of caspase-7 or Parp occurred earlier in HeLa-Cx43 than in HeLa-CTL cells. Comparative analysis of the effect of two further (endothelial) Cx (Cx37 and Cx40) on apoptosis revealed that apoptosis was highest in HeLa-Cx43 and lowest in HeLa-Cx37 cells, and correlated with the GJ permeability (assessed by spreading of a GJ-permeable dye and locally induced Ca(2+) signals). Pharmacologic inhibition of GJ formation in HeLa-Cx43 cells reduced apoptosis significantly. The role of GJ communication was further analysed by the expression of truncated Cx43 proteins with and without channel-forming capacity. Activation of caspases was higher in cells expressing the channel-building part (HeLa-Cx43NT-GFP) than in cells expressing the channel-incompetent C-terminal part of Cx43 (HeLa-Cx43CT-GFP) only. A hemichannel-dependent release and, hence, paracrine effect of proapoptotic signals could be excluded since the addition of a peptide (Pep)-blocking Cx43-dependent hemichannels (but not GJs) did not reduce apoptosis in HeLa-Cx43 cells. Treatment with SN resulted in a significant higher increase of the intracellular free Ca(2+) concentration in HeLa-Cx43 and HeLa-Cx43NT-GFP cells compared with HeLa-CTL or HeLa-Cx43CT-GFP cells, suggesting that Ca(2+) or a Ca(2+)-releasing agent could play a signalling role. Blocking of inositol triphosphate receptors reduced the SN-induced Ca(2+) increase as well as the increase in apoptosis. Our observations suggest that Cx43 and Cx40 but not Cx37 promote apoptosis via gap junctional transfer of pro-apoptotic signals between cells.
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Affiliation(s)
- P Kameritsch
- Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München and Munich University Hospital, Munich, Germany.
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23
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Johnstone SR, Billaud M, Lohman AW, Taddeo EP, Isakson BE. Posttranslational modifications in connexins and pannexins. J Membr Biol 2012; 245:319-32. [PMID: 22739962 DOI: 10.1007/s00232-012-9453-3] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Accepted: 06/08/2012] [Indexed: 01/17/2023]
Abstract
Posttranslational modification is a common cellular process that is used by cells to ensure a particular protein function. This can happen in a variety of ways, e.g., from the addition of phosphates or sugar residues to a particular amino acid, ensuring proper protein life cycle and function. In this review, we assess the evidence for ubiquitination, glycosylation, phosphorylation, S-nitrosylation as well as other modifications in connexins and pannexin proteins. Based on the literature, we find that posttranslational modifications are an important component of connexin and pannexin regulation.
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Affiliation(s)
- Scott R Johnstone
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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24
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Fang JS, Angelov SN, Simon AM, Burt JM. Cx37 deletion enhances vascular growth and facilitates ischemic limb recovery. Am J Physiol Heart Circ Physiol 2011; 301:H1872-81. [PMID: 21856908 PMCID: PMC3213969 DOI: 10.1152/ajpheart.00683.2011] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 08/15/2011] [Indexed: 12/27/2022]
Abstract
The unique contributions of connexin (Cx)37 and Cx40, gap junction-forming proteins that are coexpressed in vascular endothelium, to the recovery of tissues from ischemic injury are unknown. We recently reported that Cx37-deficient (Cx37(-/-)) animals recovered ischemic hindlimb function more quickly and to a greater extent than wild-type (WT) or Cx40(-/-) animals, suggesting that Cx37 limits recovery in the WT animal. Here, we tested the hypothesis that enhanced angiogenesis, arteriogenesis, and vasculogenesis contribute to improved postischemic hindlimb recovery in Cx37(-/-) animals. Ischemia was induced unilaterally in the hindlimbs of WT or Cx37(-/-) mice (isoflurane anesthesia). Postsurgical limb appearance, use, and perfusion were documented during recovery, and the number (and size) of large and small vessels was determined. Native collateral number, predominantly established during embryonic development (vasculogenesis), was also determined in the pial circulation. Both microvascular density in the gastrocnemius of the ischemic limb (an angiogenic field) and the number and tortuosity of larger vessels in the gracilis vasculature (an arteriogenic field) were increased in Cx37(-/-) animals compared with WT animals. Cx37(-/-) mice also had an increased (vs. WT) number of collateral vessels in the pial circulation. These findings suggest that in Cx37(-/-) animals, improved recovery of the ischemic hindlimb involves enhanced vasculogenesis, resulting in increased numbers of collaterals in the hindlimb (and pial circulations) and more extensive collateral remodeling and angiogenesis. These results are consistent with Cx37 exerting a growth-suppressive effect in the vasculature that limits embryonic vasculogenesis as well as arteriogenic and angiogenic responses to ischemic injury in the adult animal.
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Affiliation(s)
- Jennifer S Fang
- Department of Physiology, University of Arizona, Tucson, Arizona, USA
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25
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Looft-Wilson RC, Billaud M, Johnstone SR, Straub AC, Isakson BE. Interaction between nitric oxide signaling and gap junctions: effects on vascular function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1895-902. [PMID: 21835160 DOI: 10.1016/j.bbamem.2011.07.031] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 07/14/2011] [Accepted: 07/19/2011] [Indexed: 02/07/2023]
Abstract
Nitric oxide signaling, through eNOS (or possibly nNOS), and gap junction communication are essential for normal vascular function. While each component controls specific aspects of vascular function, there is substantial evidence for cross-talk between nitric oxide signaling and the gap junction proteins (connexins), and more recently, protein-protein association between eNOS and connexins. This review will examine the evidence for interaction between these pathways in normal and diseased arteries, highlight the questions that remain about the mechanisms of their interaction, and explore the possible interaction between nitric oxide signaling and the newly discovered pannexin channels. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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Affiliation(s)
- R C Looft-Wilson
- Department of Kinesiology and Health Sciences, College of William and Mary, Williamsburg, VA 23187, USA
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26
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Félétou M. The Endothelium, Part I: Multiple Functions of the Endothelial Cells -- Focus on Endothelium-Derived Vasoactive Mediators. ACTA ACUST UNITED AC 2011. [DOI: 10.4199/c00031ed1v01y201105isp019] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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27
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28
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Sauer H, Sharifpanah F, Hatry M, Steffen P, Bartsch C, Heller R, Padmasekar M, Howaldt HP, Bein G, Wartenberg M. NOS inhibition synchronizes calcium oscillations in human adipose tissue-derived mesenchymal stem cells by increasing gap-junctional coupling. J Cell Physiol 2011; 226:1642-50. [PMID: 21413022 DOI: 10.1002/jcp.22495] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Adipose tissue-derived mesenchymal stem cells (ASCs) are a promising stem cell source for cell transplantation. We demonstrate that undifferentiated ASCs display robust oscillations of intracellular calcium [Ca(2+) ](i) which may be associated with stem cell maintenance since oscillations were absent in endothelial cell differentiation medium supplemented with FGF-2. [Ca(2+) ](i) oscillations were dependent on extracellular Ca(2+) and Ca(2+) release from intracellular stores since they were abolished in Ca(2+) -free medium and in the presence of the store-depleting agent thapsigargin. They were inhibited by the phospholipase C antagonist U73,122, the inositol 1,4,5-trisphosphate (InsP(3) ) receptor antagonist 2-aminoethoxydiphenyl borate (2-APB) as well as by the gap-junction uncouplers 1-heptanol and carbenoxolone, indicating regulation by the InsP(3) pathway and dependence on gap-junctional coupling. Cells endogenously generated nitric oxide (NO), expressed NO synthase 1 (NOS 1) and connexin 43 (Cx 43). The nitric oxide NOS inhibitors NG-monomethyl-L-arginine (L-NMMA), N(G)-nitro-L-arginine methyl ester (L-NAME), 2-ethyl-2-thiopseudourea, and diphenylene iodonium as well as si-RNA-mediated down-regulation of NOS 1 synchronized [Ca(2+) ](i) oscillations between individual cells, whereas the NO-donors S-nitroso-N-acetylpenicillamine (SNAP) and sodium nitroprusside (SNP) as well as the soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ) were without effects. The synchronization of [Ca(2+) ](i) oscillations was due to an improvement of intracellular coupling since fluorescence recovery after photobleaching (FRAP) revealed increased reflow of fluorescent calcein into the bleached area in the presence of the NOS inhibitors DPI and L-NAME. In summary our data demonstrate that intracellular NO levels regulate synchronization of [Ca(2+) ](i) oscillations in undifferentiated ASCs by controlling gap-junctional coupling.
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Affiliation(s)
- Heinrich Sauer
- Department of Physiology, Justus Liebig University Giessen, Germany.
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29
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Mogensen C, Bergner B, Wallner S, Ritter A, d'Avis S, Ninichuk V, Kameritsch P, Gloe T, Nagel W, Pohl U. Isolation and functional characterization of pericytes derived from hamster skeletal muscle. Acta Physiol (Oxf) 2011; 201:413-26. [PMID: 20969729 DOI: 10.1111/j.1748-1716.2010.02206.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
AIM At the interface of tissue and capillaries, pericytes (PC) may generate electrical signals to be conducted along the skeletal muscle vascular network, but they are functionally not well characterized. We aimed to isolate and cultivate muscle PC allowing to analyse functional properties considered important for signal generation and conduction. METHODS Pericytes were enzymatically isolated from hamster thigh muscles and further selected during a 16-30 days' cultivation period. PC markers were studied by fluorescence activated cell scanning (FACS) and immunocytochemistry. Electrical properties of the cultured PC were investigated by patch clamp technique as well as the membrane potential sensitive dye DiBAC(4) (3). RESULTS The cultured cells showed typical PC morphology and were positive for NG2, alpha smooth muscle actin, PDGFR-β and the gap junction protein Cx43. Expressions of at least one single or combinations of several markers were found in 80-90% of subpopulations. A subset of the patched cells expressed channel activities consistent with a Kv1.5 channel. In vivo presence of the channels was confirmed in sections of hamster thigh muscles. Interleukin-8, a myokine known to be released from exercising muscle, increased the expression but not the activity of this channel. Pharmacologic stimulation of the channel activity by flufenamic acid induced hyperpolarization of PC alone but not of endothelial cells [human umbilical vein endothelial cells (HUVEC)] alone. However, hyperpolarization was observed in HUVEC adjacent to PC when kept in co-culture. CONCLUSION We established a culture method for PC from skeletal muscle. A first functional characterization revealed properties which potentially enable these cells to generate hyperpolarizing signals and to communicate them to endothelial cells.
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Affiliation(s)
- C Mogensen
- Walter-Brendel-Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
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30
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Potential mechanisms of prospective antimigraine drugs: A focus on vascular (side) effects. Pharmacol Ther 2011; 129:332-51. [DOI: 10.1016/j.pharmthera.2010.12.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 11/09/2010] [Indexed: 12/13/2022]
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31
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Lee NPY, Cheng CY. Nitric oxide and cyclic nucleotides: their roles in junction dynamics and spermatogenesis. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2011; 1:25-32. [PMID: 19794905 PMCID: PMC2715196 DOI: 10.4161/oxim.1.1.6856] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Spermatogenesis is a highly complicated process in which functional spermatozoa (haploid, 1n) are generated from primitive mitotic spermatogonia (diploid, 2n). This process involves the differentiation and transformation of several types of germ cells as spermatocytes and spermatids undergo meiosis and differentiation. Due to its sophistication and complexity, testis possesses intrinsic mechanisms to modulate and regulate different stages of germ cell development under the intimate and indirect cooperation with Sertoli and Leydig cells, respectively. Furthermore, developing germ cells must translocate from the basal to the apical (adluminal) compartment of the seminiferous epithelium. Thus, extensive junction restructuring must occur to assist germ cell movement. Within the seminiferous tubules, three principal types of junctions are found namely anchoring junctions, tight junctions, and gap junctions. Other less studied junctions are desmosome-like junctions and hemidesmosome junctions. With these varieties of junction types, testes are using different regulators to monitor junction turnover. Among the uncountable junction modulators, nitric oxide (NO) is a prominent candidate due to its versatility and extensive downstream network. NO is synthesized by nitric oxide synthase (NOS). Three traditional NOS, specified as endothelial NOS (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS), and one testis-specific nNOS (TnNOS) are found in the testis. For these, eNOS and iNOS were recently shown to have putative junction regulation properties. More important, these two NOSs likely rely on the downstream soluble guanylyl cyclase/cGMP/protein kinase G signaling pathway to regulate the structural components at the tight junctions and adherens junctions in the testes. Apart from the involvement in junction regulation, NOS/NO also participates in controlling the levels of cytokines and hormones in the testes. On the other hand, NO is playing a unique role in modulating germ cell viability and development, and indirectly acting on some aspects of male infertility and testicular pathological conditions. Thus, NOS/NO bears an irreplaceable role in maintaining the homeostasis of the microenvironment in the seminiferous epithelium via its different downstream signaling pathways.
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Affiliation(s)
- Nikki P Y Lee
- Department of Medicine/Surgery, University of Hong Kong, Queen Mary Hospital, Hong Kong, China.
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32
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Tyml K. Role of connexins in microvascular dysfunction during inflammation. Can J Physiol Pharmacol 2011; 89:1-12. [DOI: 10.1139/y10-099] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In arterioles, a locally initiated diameter change can propagate rapidly along the vessel length (arteriolar conducted response), thus contributing to arteriolar hemodynamic resistance. The response is underpinned by electrical coupling along the arteriolar endothelial layer. Connexins (Cx; constituents of gap junctions) are required for this coupling. This review addresses the effect of acute systemic inflammation (sepsis) on arteriolar conduction and interendothelial electrical coupling. Lipopolysaccharide (LPS; an initiating factor in sepsis) and polymicrobial sepsis (24 h model) attenuate conducted vasoconstriction in mice. In cultured microvascular endothelial cells harvested from rat and mouse skeletal muscle, LPS reduces both conducted hyperpolarization–depolarization along capillary-like structures and electrical coupling along confluent cell monolayers. LPS also tyrosine-phosphorylates Cx43 and serine-dephosphorylates Cx40. Since LPS-reduced coupling is Cx40- but not Cx43-dependent, only Cx40 dephosphorylation may be consequential. Nitric oxide (NO) overproduction is critical in advanced sepsis, since the removal of this overproduction prevents the attenuated conduction. Consistently, (i) exogenous NO in cultured cells reduces coupling in a Cx37-dependent manner, and (ii) the septic microvasculature in vivo shows no Cx40 phenotype. A complex role emerges for endothelial connexins in sepsis. Initially, LPS may reduce interendothelial coupling and arteriolar conduction by targeting Cx40, whereas NO overproduction in advanced sepsis reduces coupling and conduction by targeting Cx37 instead.
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Affiliation(s)
- Karel Tyml
- Department of Medical Biophysics, and Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
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33
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Straub AC, Billaud M, Johnstone SR, Best AK, Yemen S, Dwyer ST, Looft-Wilson R, Lysiak JJ, Gaston B, Palmer L, Isakson BE. Compartmentalized connexin 43 s-nitrosylation/denitrosylation regulates heterocellular communication in the vessel wall. Arterioscler Thromb Vasc Biol 2010; 31:399-407. [PMID: 21071693 DOI: 10.1161/atvbaha.110.215939] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVE To determine whether S-nitrosylation of connexins (Cxs) modulates gap junction communication between endothelium and smooth muscle. METHODS AND RESULTS Heterocellular communication is essential for endothelium control of smooth muscle constriction; however, the exact mechanism governing this action remains unknown. Cxs and NO have been implicated in regulating heterocellular communication in the vessel wall. The myoendothelial junction serves as a conduit to facilitate gap junction communication between endothelial cells and vascular smooth muscle cells within the resistance vasculature. By using isolated vessels and a vascular cell coculture, we found that Cx43 is constitutively S-nitrosylated on cysteine 271 because of active endothelial NO synthase compartmentalized at the myoendothelial junction. Conversely, we found that stimulation of smooth muscle cells with the constrictor phenylephrine caused Cx43 to become denitrosylated because of compartmentalized S-nitrosoglutathione reductase, which attenuated channel permeability. We measured S-nitrosoglutathione breakdown and NO(x) concentrations at the myoendothelial junction and found S-nitrosoglutathione reductase activity to precede NO release. CONCLUSIONS This study provides evidence for compartmentalized S-nitrosylation/denitrosylation in the regulation of smooth muscle cell to endothelial cell communication.
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MESH Headings
- Alcohol Dehydrogenase
- Animals
- Cell Communication/physiology
- Cells, Cultured
- Connexin 43/metabolism
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Gap Junctions/metabolism
- Glutathione Reductase/genetics
- Glutathione Reductase/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Models, Animal
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Nitric Oxide/metabolism
- Nitric Oxide Synthase Type III/metabolism
- Phenylephrine/pharmacology
- S-Nitrosoglutathione/metabolism
- Vascular Resistance/physiology
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Adam C Straub
- Department of Molecular Physiology and Biological Physics, Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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34
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Radosinska J, Bacova B, Bernatova I, Navarova J, Zhukovska A, Shysh A, Okruhlicova L, Tribulova N. Myocardial NOS activity and connexin-43 expression in untreated and omega-3 fatty acids-treated spontaneously hypertensive and hereditary hypertriglyceridemic rats. Mol Cell Biochem 2010; 347:163-73. [PMID: 20963625 DOI: 10.1007/s11010-010-0625-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Accepted: 10/06/2010] [Indexed: 12/21/2022]
Abstract
The purpose of this study is to investigate myocardial nitric oxide synthase (NOS) activity and connexin-43 (Cx43) expression in young and old spontaneously hypertensive rats (SHR), adult hereditary hypertriglyceridemic (HTG) rats, and age-matched healthy rats without and with omega-3 PUFA supplementation for 2 months. Results showed that comparing to healthy rats the myocardial NOS activity was significantly increased in young SHR (8.2 ± 1.16 vs. 1.37 ± 0.67 pmol/min/mg) as well as old SHR (3.21 ± 0.75 vs. 2.22 ± 0.56 pmol/min/mg) and to much lesser extent in HTG rats, i.e., 1.87 ± 0.42 vs. 1.34 ± 0.1 pmol/min/mg. In parallel, there was a significant decline of total and phosphorylated forms of Cx43 in both groups of SHR while not in HTG rat hearts in which phosphorylated form of Cx43 was increased. Elevated NOS activity was suppressed (P < 0.05) in young and old SHR supplemented with omega-3 PUFA and it was associated with up-regulation of Cx43. In contrast to SHR, elevation of NOS activity in HTG rat hearts was not affected by treatment with omega-3 PUFA. However, increase of phosphorylated form of Cx43 was suppressed. In conclusion, there is an inverse relationship between myocardial NOS activity and Cx43 expression in SHR while not HTG rat hearts and omega-3 PUFA modulate both NOS activity and Cx43 expression. Whether over-expression of inducible NOS might account for down-regulation of myocardial Cx43 and whether its up-regulation is associated with an increase of endothelial NOS should be explored in further study.
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Affiliation(s)
- Jana Radosinska
- Institute for Heart Research, Slovak Academy of Sciences, Dúbravská cesta 9, P.O. Box 104, 840 05, Bratislava, Slovakia
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35
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Pfenniger A, Derouette JP, Verma V, Lin X, Foglia B, Coombs W, Roth I, Satta N, Dunoyer-Geindre S, Sorgen P, Taffet S, Kwak BR, Delmar M. Gap junction protein Cx37 interacts with endothelial nitric oxide synthase in endothelial cells. Arterioscler Thromb Vasc Biol 2010; 30:827-34. [PMID: 20081116 PMCID: PMC2930827 DOI: 10.1161/atvbaha.109.200816] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE The gap junction protein connexin37 (Cx37) plays an important role in cell-cell communication in the vasculature. A C1019T Cx37 gene polymorphism, encoding a P319S substitution in the regulatory C terminus of Cx37 (Cx37CT), correlates with arterial stenosis and myocardial infarction in humans. This study was designed to identify potential binding partners for Cx37CT and to determine whether the polymorphism modified this interaction. METHODS AND RESULTS Using a high-throughput phage display, we retrieved 2 binding motifs for Cx37CT: WHK ... [K,R]XP ... and FHK ... [K,R]XXP ... , the first being more common for Cx37CT-319P and the second more common for Cx37CT-319S. One of the peptides (WHRTPRLPPPVP) showed 77.7% homology with residues 843 to 854 of endothelial nitric oxide synthase (eNOS). In vitro binding of this peptide or of the homologous eNOS sequence to both Cx37CT isoforms was confirmed by cross-linking and surface plasmon resonance. Electrophysiological analysis of Cx37 single channel activity in transfected N2a cells showed that eNOS-like and eNOS(843-854) increased the frequency of events with conductances higher than 300 pS. We demonstrated that eNOS coimmunoprecipitated with Cx37 in a mouse endothelial cell (EC) line (bEnd.3), human primary ECs, and a human EC line transfected with Cx37-319P or Cx37-319S. Cx37 and eNOS colocalized at EC membranes. Moreover, a dose-dependent increase in nitric oxide production was observed in ECs treated with Cx37 antisense. CONCLUSIONS Overall, our data show for the first time a functional and specific interaction between eNOS and Cx37. This interaction may be relevant for the control of vascular physiology both in health and in disease.
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Affiliation(s)
- Anna Pfenniger
- Division of Cardiology, Department of Internal Medicine, Faculty of Medicine, University of Geneva, Switzerland.
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36
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McKinnon RL, Bolon ML, Wang HX, Swarbreck S, Kidder GM, Simon AM, Tyml K. Reduction of electrical coupling between microvascular endothelial cells by NO depends on connexin37. Am J Physiol Heart Circ Physiol 2009; 297:H93-H101. [PMID: 19429814 PMCID: PMC2711744 DOI: 10.1152/ajpheart.01148.2008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Accepted: 05/07/2009] [Indexed: 11/22/2022]
Abstract
We have previously shown that increased nitric oxide (NO) production in sepsis impairs arteriolar-conducted vasoconstriction cGMP independently and that the gap junction protein connexin (Cx) 37 is required for this conducted response. In the present study, we hypothesized that NO impairs interendothelial electrical coupling in sepsis by targeting Cx37. We examined the effect of exogenous NO on coupling in monolayers of cultured microvascular endothelial cells derived from the hindlimb skeletal muscle of wild-type (WT), Cx37 null, Cx40 null, and Cx43(G60S) (nonfunctional mutant) mice. To assess coupling, we measured the spread of electrical current injected in the monolayer and calculated the monolayer intercellular resistance (inverse measure of coupling). The NO donor 2,2'-(hydroxynitrosohydrazino)bis-ethanamine (DETA) rapidly and reversibly reduced coupling in cells from WT mice, cGMP independently. NO scavenger HbO(2) did not affect baseline coupling, but it eliminated DETA-induced reduction in coupling. Reduced coupling in response to DETA was also seen in cells from Cx40 null and Cx43(G60S) mice, but not in cells from Cx37 null mice. DETA did not alter the expression of Cx37, Cx40, and Cx43 in WT cells analyzed by immunoblotting and immunofluorescence. Furthermore, neither the peroxynitrite scavenger 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato iron (III), superoxide scavenger Mn(III)tetrakis(4-benzoic acid)porphyrin chloride, nor preloading of WT cells with the antioxidant ascorbate affected this reduction. We conclude that NO-induced reduction of electrical coupling between microvascular endothelial cells depends on Cx37 and propose that NO in sepsis impairs arteriolar-conducted vasoconstriction by targeting Cx37 within the arteriolar wall.
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Affiliation(s)
- Rebecca L McKinnon
- Critical Illness Research, Lawson Health Research Institute, London, Ontario, Canada
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37
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Just A, Kurtz L, de Wit C, Wagner C, Kurtz A, Arendshorst WJ. Connexin 40 mediates the tubuloglomerular feedback contribution to renal blood flow autoregulation. J Am Soc Nephrol 2009; 20:1577-85. [PMID: 19443640 PMCID: PMC2709687 DOI: 10.1681/asn.2008090943] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2008] [Accepted: 03/05/2009] [Indexed: 12/30/2022] Open
Abstract
Connexins are important in vascular development and function. Connexin 40 (Cx40), which plays a predominant role in the formation of gap junctions in the vasculature, participates in the autoregulation of renal blood flow (RBF), but the underlying mechanisms are unknown. Here, Cx40-deficient mice (Cx40-ko) had impaired steady-state autoregulation to a sudden step increase in renal perfusion pressure. Analysis of the mechanisms underlying this derangement suggested that a marked reduction in tubuloglomerular feedback (TGF) in Cx40-ko mice was responsible. In transgenic mice with Cx40 replaced by Cx45, steady-state autoregulation and TGF were weaker than those in wild-type mice but stronger than those in Cx40-ko mice. N omega-Nitro-L-arginine-methyl-ester (L-NAME) augmented the myogenic response similarly in all genotypes, leaving autoregulation impaired in transgenic animals. The responses of renovascular resistance and arterial pressure to norepinephrine and acetylcholine were similar in all groups before or after L-NAME inhibition. Systemic and renal vasoconstrictor responses to L-NAME were also similar in all genotypes. We conclude that Cx40 contributes to RBF autoregulation by transducing TGF-mediated signals to the afferent arteriole, a function that is independent of nitric oxide (NO). However, Cx40 is not required for the modulation of the renal myogenic response by NO, norepinephrine-induced renal vasoconstriction, and acetylcholine- or NO-induced vasodilation.
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Affiliation(s)
- Armin Just
- Department of Cell & Molecular Physiology, Carolina Cardiovascular Biology Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
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38
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Heberlein KR, Straub AC, Isakson BE. The myoendothelial junction: breaking through the matrix? Microcirculation 2009; 16:307-22. [PMID: 19330678 DOI: 10.1080/10739680902744404] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Within the vasculature, specialized cellular extensions from endothelium (and sometimes smooth muscle) protrude through the extracellular matrix where they interact with the opposing cell type. These structures, termed myoendothelial junctions, have been cited as a possible key element in the control of several vascular physiologies and pathologies. This review will discuss observations that have led to a focus on the myoendothelial junction as a cellular integration point in the vasculature for both homeostatic and pathological conditions and as a possible independent signaling entity. We will also highlight the need for novel approaches to studying the myoendothelial junction in order to comprehend the cellular biology associated with this structure.
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Affiliation(s)
- Katherine R Heberlein
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottsville, Virginia 22908, USA
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39
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Hilgers RHP, De Mey JGR. Myoendothelial coupling in the mesenteric arterial bed; segmental differences and interplay between nitric oxide and endothelin-1. Br J Pharmacol 2009; 156:1239-47. [PMID: 19302591 DOI: 10.1111/j.1476-5381.2009.00128.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND AND PURPOSE We tested the hypothesis that activated arterial smooth muscle (ASM) stimulates endothelial vasomotor influences via gap junctions and that the significance of this myoendothelial coupling increases with decreasing arterial diameter. EXPERIMENTAL APPROACH From WKY rats, first-, second-, third- and fourth-order branches of the superior mesenteric artery (MA1, MA2, MA3 and MA4 respectively) were isolated and mounted in wire-myographs to record vasomotor responses to 0.16-20 micromol x L(-1) phenylephrine. KEY RESULTS Removal of endothelium increased the sensitivity (pEC(50)) to phenylephrine in all arteries. The nitric oxide (NO) synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) (100 micromol x L(-1)) did not modify pEC(50) to phenylephrine in all denuded arteries, and increased it in intact MA1, MA2 and MA3 to the same extent as denudation. However, in intact MA4, the effect of L-NAME was significantly larger (DeltapEC(50) 0.57 +/- 0.02) than the effect of endothelium removal (DeltapEC(50) 0.20 +/- 0.06). This endothelium-dependent effect of L-NAME in MA4 was inhibited by (i) steroidal and peptidergic uncouplers of gap junctions; (ii) a low concentration of the NO donor sodium nitroprusside; and (iii) by the endothelin-receptor antagonist bosentan. It was also observed during contractions induced by (i) calcium channel activation (BayK 8644, 0.001-1 micromol x L(-1)); (ii) depolarization (10-40 mmol x L(-1) K(+)); and (iii) sympathetic nerve stimulation (0.25-32 Hz). CONCLUSIONS AND IMPLICATIONS These pharmacological observations indicated feedback control by endothelium of ASM reactivity involving gap junctions and a balance between endothelium-derived NO and endothelin-1. This myoendothelial coupling was most prominent in distal resistance arteries.
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Affiliation(s)
- R H P Hilgers
- Department of Pharmacology and Toxicology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, The Netherlands
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40
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Lee NPY, Cheng CY. Nitric oxide and cyclic nucleotides: their roles in junction dynamics and spermatogenesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 636:172-85. [PMID: 19856168 DOI: 10.1007/978-0-387-09597-4_10] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Spermatogenesis is a highly complicated process in which functional spermatozoa (haploid, 1n) are generated from primitive mitotic spermatogonia (diploid, 2n). This process involves the differentiation and transformation of several types of germ cells as spermatocytes and spermatids undergo meiosis and differentiation. Due to its sophistication and complexity, testis possesses intrinsic mechanisms to modulate and regulate different stages of germ cell development under the intimate and indirect cooperation with Sertoli and Leydig cells, respectively. Furthermore, developing germ cells must translocate from the basal to the apical (adluminal) compartment of the seminiferous epithelium. Thus, extensive junction restructuring must occur to assist germ cell movement. Within the seminiferous tubules, three principal types of junctions are found namely anchoring junctions, tight junctions, and gap junctions. Other less studied junctions are desmosome-like junctions and hemidesmosome junctions. With these varieties of junction types, testes are using different regulators to monitor junction turnover. Among the uncountable junction modulators, nitric oxide (NO) is a prominent candidate due to its versatility and extensive downstream network. NO is synthesized by nitric oxide synthase (NOS). Three traditional NOS, specified as endothelial NOS (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS), and one testis-specific nNOS (TnNOS) are found in the testis. For these, eNOS and iNOS were recently shown to have putative junction regulation properties. More important, these two NOSs likely rely on the downstream soluble guanylyl cyclase/cGMP/protein kinase G signaling pathway to regulate the structural components at the tight junctions and adherens junctions in the testes. Apart from the involvement in junction regulation, NOS/NO also participates in controlling the levels of cytokines and hormones in the testes. On the other hand, NO is playing a unique role in modulating germ cell viability and development, and indirectly acting on some aspects of male infertility and testicular pathological conditions. Thus, NOS/NO bears an irreplaceable role in maintaining the homeostasis of the microenvironment in the seminiferous epithelium via its different downstream signaling pathways.
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Affiliation(s)
- Nikki P Y Lee
- Department of Medicine and Surgery, University of Hong Kong, Queen Mary Hospital, Hong Kong, China.
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41
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Johnstone S, Isakson B, Locke D. Biological and biophysical properties of vascular connexin channels. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 278:69-118. [PMID: 19815177 PMCID: PMC2878191 DOI: 10.1016/s1937-6448(09)78002-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intercellular channels formed by connexin proteins play a pivotal role in the direct movement of ions and larger cytoplasmic solutes between vascular endothelial cells, between vascular smooth muscle cells, and between endothelial and smooth muscle cells. Multiple genetic and epigenetic factors modulate connexin expression levels and/or channel function, including cell-type-independent and cell-type-specific transcription factors, posttranslational modifications, and localized membrane targeting. Additionally, differences in protein-protein interactions, including those between connexins, significantly contribute to both vascular homeostasis and disease progression. The biophysical properties of the connexin channels identified in the vasculature, those formed by Cx37, Cx40, Cx43 and/or Cx45 proteins, are discussed in this chapter in the physiological and pathophysiological context of vessel function.
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Affiliation(s)
- Scott Johnstone
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 29908
| | - Brant Isakson
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 29908
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 29908
| | - Darren Locke
- Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103
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Chang Q, Tang W, Ahmad S, Zhou B, Lin X. Gap junction mediated intercellular metabolite transfer in the cochlea is compromised in connexin30 null mice. PLoS One 2008; 3:e4088. [PMID: 19116647 PMCID: PMC2605248 DOI: 10.1371/journal.pone.0004088] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Accepted: 12/02/2008] [Indexed: 11/19/2022] Open
Abstract
Connexin26 (Cx26) and connexin30 (Cx30) are two major protein subunits that co-assemble to form gap junctions (GJs) in the cochlea. Mutations in either one of them are the major cause of non-syndromic prelingual deafness in humans. Because the mechanisms of cochlear pathogenesis caused by Cx mutations are unclear, we investigated effects of Cx30 null mutation on GJ-mediated ionic and metabolic coupling in the cochlea of mice. A novel flattened cochlear preparation was used to directly assess intercellular coupling in the sensory epithelium of the cochlea. Double-electrode patch clamp recordings revealed that the absence of Cx30 did not significantly change GJ conductance among the cochlear supporting cells. The preserved electrical coupling is consistent with immunolabeling data showing extensive Cx26 GJs in the cochlea of the mutant mice. In contrast, dye diffusion assays showed that the rate and extent of intercellular transfer of multiple fluorescent dyes (including a non-metabolizable D-glucose analogue, 2-NBDG) among cochlear supporting cells were severely reduced in Cx30 null mice. Since the sensory epithelium in the cochlea is an avascular organ, GJ-facilitated intercellular transfer of nutrient and signaling molecules may play essential roles in cellular homeostasis. To test this possibility, NBDG was used as a tracer to study the contribution of GJs in transporting glucose into the cochlear sensory epithelium when delivered systemically. NBDG uptake in cochlear supporting cells was significantly reduced in Cx30 null mice. The decrease was also observed with GJ blockers or glucose competition, supporting the specificity of our tests. These data indicate that GJs facilitate efficient uptake of glucose in the supporting cells. This study provides the first direct experimental evidence showing that the transfer of metabolically-important molecules in cochlear supporting cells is dependent on the normal function of GJs, thereby suggesting a novel pathogenesis process in the cochlea for Cx-mutation-linked deafness.
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Affiliation(s)
- Qing Chang
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Wenxue Tang
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Shoeb Ahmad
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Binfei Zhou
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Xi Lin
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, Georgia, United States of America
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
- * E-mail: .
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Wojciak-Stothard B, Torondel B, Zhao L, Renné T, Leiper JM. Modulation of Rac1 activity by ADMA/DDAH regulates pulmonary endothelial barrier function. Mol Biol Cell 2008; 20:33-42. [PMID: 18923147 DOI: 10.1091/mbc.e08-04-0395] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Endogenously produced nitric oxide synthase inhibitor, asymmetric methylarginine (ADMA) is associated with vascular dysfunction and endothelial leakage. We studied the role of ADMA, and the enzymes metabolizing it, dimethylarginine dimethylaminohydrolases (DDAH) in the regulation of endothelial barrier function in pulmonary macrovascular and microvascular cells in vitro and in lungs of genetically modified heterozygous DDAHI knockout mice in vivo. We show that ADMA increases pulmonary endothelial permeability in vitro and in in vivo and that this effect is mediated by nitric oxide (NO) acting via protein kinase G (PKG) and independent of reactive oxygen species formation. ADMA-induced remodeling of actin cytoskeleton and intercellular adherens junctions results from a decrease in PKG-mediated phosphorylation of vasodilator-stimulated phosphoprotein (VASP) and a subsequent down-regulation of Rac1 activity. The effects of ADMA on endothelial permeability, Rac1 activation and VASP phosphorylation are prevented by overexpression of active DDAHI and DDAHII, whereas inactive DDAH mutants have no effect. These findings demonstrate for the first time that ADMA metabolism critically determines pulmonary endothelial barrier function by modulating Rac1-mediated remodeling of the actin cytoskeleton and intercellular junctions.
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44
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Isakson BE, Best AK, Duling BR. Incidence of protein on actin bridges between endothelium and smooth muscle in arterioles demonstrates heterogeneous connexin expression and phosphorylation. Am J Physiol Heart Circ Physiol 2008; 294:H2898-904. [PMID: 18408134 DOI: 10.1152/ajpheart.91488.2007] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although much physiology in resistance vessels has been attributed to the cytoplasmic connection between endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), little is known of the protein expression between the two cell types. In an attempt to identify the proteins between ECs and VSMCs, mouse cremaster arterioles were stained with phalloidin-Alexa 594 and viewed on a confocal microscope that resolved "actin bridges" within the internal elastic lamina between ECs and VSMCs. To determine the incidence of protein, the pixel intensity from the antibodies on actin bridges were compared with the pixel intensity from antibodies within ECs or VSMCs. N-cadherin, desmin, connexin (Cx)40, and Cx43 and phosphorylated Cx43 at serine-368 were identified on actin bridges, but NG2, CD31, and Cx45 were not evident. Cx37 expression was more variable than the other connexins examined. Using this method on rat mesentery, we confirm the previously published predominance of Cx37 and Cx40 at the myoendothelial junction that was determined using electron microscopy. We conclude that this new method represents an important screening mechanism in which to rapidly test for protein expression between ECs and VSMCs and possibly a first-step in quantifying protein expression at the myoendothelial junction.
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Affiliation(s)
- Brant E Isakson
- Department of Molecular Physiology and Biological Physics, University of Virginia Health Science System, Charlottesville, Virginia, USA
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45
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Alpert MH, Zhang H, Molinari M, Heitler WJ, Sillar KT. Nitric oxide modulation of the electrically excitable skin of Xenopus laevis frog tadpoles. ACTA ACUST UNITED AC 2008; 210:3910-8. [PMID: 17981858 DOI: 10.1242/jeb.009662] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Nitric oxide (NO) is a highly diffusible signalling molecule with widespread effects on the integrative electrical properties of a variety of neuronal and muscle cells. We have explored the effects of NO on the cardiac-like impulse generated by skin cells of the hatchling Xenopus tadpole. Skin cell impulses propagate from cell to cell via gap junctions and form an unusual sensory system, which triggers escape behaviour at early stages of amphibian development. We show that the NO donor S-nitroso-N-acetylpenicillamine (SNAP) increases the duration of the skin impulse and slows the rate of impulse propagation across the skin, and also produces a significant depolarization of the membrane potential of skin cells. Each of these effects of SNAP is significantly reversed by the NO scavenger, C-PTIO. Possible sources of NO have been investigated using both NADPH-diaphorase histochemistry and nNOS immunocytochemistry to label the enzyme nitric oxide synthase (NOS), and DAF-2 to label NO itself. In each case a punctate distribution of skin cells is labelled, indicating that the endogenous production of NO may regulate the properties of the skin impulse.
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Affiliation(s)
- Michael H Alpert
- School of Biology, University of St Andrews, St Andrews, Fife, KY16 9TS, UK
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46
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Anand RJ, Dai S, Rippel C, Leaphart C, Qureshi F, Gribar SC, Kohler JW, Li J, Stolz DB, Sodhi C, Hackam DJ. Activated macrophages inhibit enterocyte gap junctions via the release of nitric oxide. Am J Physiol Gastrointest Liver Physiol 2008; 294:G109-19. [PMID: 17975131 DOI: 10.1152/ajpgi.00331.2007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Enterocytes exist in close association with tissue macrophages, whose activation during inflammatory processes leads to the release of nitric oxide (NO). Repair from mucosal injury requires the migration of enterocytes into the mucosal defect, a process that requires connexin43 (Cx43)-mediated gap junction communication between adjacent enterocytes. Enterocyte migration is inhibited during inflammatory conditions including necrotizing enterocolitis, in part, through impaired gap junction communication. We now hypothesize that activated macrophages inhibit gap junctions of adjacent enterocytes and seek to determine whether NO release from macrophages was involved. Using a coculture system of enterocytes and macrophages, we now demonstrate that "activation" of macrophages with lipopolysaccharide and interferon reduces the phosphorylation of Cx43 in adjacent enterocytes, an event known to inhibit gap junction communication. The effects of macrophages on enterocyte gap junctions could be reversed by treatment of macrophages with the inducible nitric oxide synthase (iNOS) inhibitor l-Lysine omega-acetamidine hydrochloride (l-NIL) and by incubation with macrophages from iNOS(-/-) mice, implicating NO in the process. Activated macrophages also caused a NO-dependent redistribution of connexin43 in adjacent enterocytes from the cell surface to an intracellular location, further suggesting NO release may inhibit gap junction function. Treatment of enterocytes with the NO donor S-nitroso-N-acetylpenicillamine (SNAP) markedly inhibited gap junction communication as determined using single cell microinjection of the gap junction tracer Lucifer yellow. Strikingly, activated macrophages inhibited enterocyte migration into a scraped wound, which was reversed by l-NIL pretreatment. These results implicate enterocyte gap junctions as a target of the NO-mediated effects of macrophages during intestinal inflammation, particularly where enterocyte migration is impaired.
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Affiliation(s)
- Rahul J Anand
- Department of Surgery, Children's Hospital of Pittsburgh, Pittsburgh, PA 15213, USA
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47
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Rodenwaldt B, Pohl U, de Wit C. Endogenous and exogenous NO attenuates conduction of vasoconstrictions along arterioles in the microcirculation. Am J Physiol Heart Circ Physiol 2007; 292:H2341-8. [PMID: 17220177 DOI: 10.1152/ajpheart.01061.2006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vascular coordination in the microcirculation depends on gap junctional intercellular communication (GJIC), which is reflected by the conduction of locally initiated vasomotor responses. However, little is known about the regulation of GJIC in vivo. We hypothesized that endothelial NO regulates GJIC and therefore studied whether conduction of constrictions and dilations along the vessel wall is modulated by modifying the level of microcirculatory NO. Arterioles were focally stimulated using high K(+) or acetylcholine in the cremaster muscle in situ, and diameter changes were assessed at the local and remote upstream sites by intravital microscopy. Local stimulation with K(+) initiated a constriction that conducted along the arteriole with diminishing amplitude (length constant lambda: 371 +/- 42 mum). After N(omega)-nitro-l-arginine (l-NNA), lambda increased to 507 +/- 30 mum, indicating that GJIC is attenuated by endogenous NO. Exogenous NO, but not adenosine, reduced lambda after l-NNA in a reversible, concentration-dependent, and mainly cGMP-dependent manner as assessed by inhibition of soluble guanylate cyclase. In endothelial NO synthase-deficient mice, lambda was 530 +/- 80 mum and thus similar to that in wild-type mice after l-NNA. Exogenous NO likewise reduced lambda in these mice. The effects of NO were comparable to those of wild-type animals in Cx40-deficient mice, which excludes Cx40 as a specific target of NO. In contrast to constrictions, the amplitude of conducted dilations on acetylcholine did not diminish up to 1,300 mum and were not altered by l-NNA or exogenous NO. We conclude that endogenously released NO attenuates the conduction of vasoconstrictions most likely due to a modulation of gap junctional conductivity. We suggest that this effect is specific for smooth muscle cells, which probably transmit constricting signals, and involves connexins other than Cx40. This mechanism may support the dilatory potency of NO by preventing the conduction of remote vasoconstrictions into areas with basal or activated NO release.
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Affiliation(s)
- Barbara Rodenwaldt
- Physiologisches Institut, Universität Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
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Zhao Z, Walczysko P, Zhao M. Intracellular Ca2+ stores are essential for injury induced Ca2+ signaling and re-endothelialization. J Cell Physiol 2007; 214:595-603. [DOI: 10.1002/jcp.21248] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Affiliation(s)
- Xavier F Figueroa
- Unidad de Regulación Neurohumoral, Departamento de Ciencias Fisiológicas, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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Just A. Mechanisms of renal blood flow autoregulation: dynamics and contributions. Am J Physiol Regul Integr Comp Physiol 2006; 292:R1-17. [PMID: 16990493 DOI: 10.1152/ajpregu.00332.2006] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Autoregulation of renal blood flow (RBF) is caused by the myogenic response (MR), tubuloglomerular feedback (TGF), and a third regulatory mechanism that is independent of TGF but slower than MR. The underlying cause of the third regulatory mechanism remains unclear; possibilities include ATP, ANG II, or a slow component of MR. Other mechanisms, which, however, exert their action through modulation of MR and TGF are pressure-dependent change of proximal tubular reabsorption, resetting of RBF and TGF, as well as modulating influences of ANG II and nitric oxide (NO). MR requires < 10 s for completion in the kidney and normally follows first-order kinetics without rate-sensitive components. TGF takes 30-60 s and shows spontaneous oscillations at 0.025-0.033 Hz. The third regulatory component requires 30-60 s; changes in proximal tubular reabsorption develop over 5 min and more slowly for up to 30 min, while RBF and TGF resetting stretch out over 20-60 min. Due to these kinetic differences, the relative contribution of the autoregulatory mechanisms determines the amount and spectrum of pressure fluctuations reaching glomerular and postglomerular capillaries and thereby potentially impinge on filtration, reabsorption, medullary perfusion, and hypertensive renal damage. Under resting conditions, MR contributes approximately 50% to overall RBF autoregulation, TGF 35-50%, and the third mechanism < 15%. NO attenuates the strength, speed, and contribution of MR, whereas ANG II does not modify the balance of the autoregulatory mechanisms.
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Affiliation(s)
- Armin Just
- Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7545, USA.
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