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Abstract
Connexins are a family of gap junction forming proteins widely expressed by mammalian cells. They assemble into hexameric hemichannels, which can either function independently or dock with opposing hemichannels on apposite cells, forming a gap junction. Pannexins are structurally related to the connexins but extensive glycosylation of these channels prevents docking to form gap junctions and they function as membrane channels. Platelets express pannexin-1 and several connexin family members (Cx37, Cx40 and Cx62). These channels are permeable to molecules up to 1,000 Daltons in molecular mass and functional studies demonstrate their role in non-vesicular ATP release. Channel activation is regulated by (patho)physiological stimuli, such as mechanical stimulation, making them attractive potential drug targets for the management of arterial thrombosis. This review explores the structure and function of platelet pannexin-1 and connexins, the mechanisms by which they are gated and their therapeutic potential.
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Affiliation(s)
- Kirk A Taylor
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK.,National Heart and Lung Institute, Imperial College London, London, UK
| | - Gemma Little
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
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2
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Abstract
Renin cells are essential for survival perfected throughout evolution to ensure normal development and defend the organism against a variety of homeostatic threats. During embryonic and early postnatal life, they are progenitors that participate in the morphogenesis of the renal arterial tree. In adult life, they are capable of regenerating injured glomeruli, control blood pressure, fluid-electrolyte balance, tissue perfusion, and in turn, the delivery of oxygen and nutrients to cells. Throughout life, renin cell descendants retain the plasticity or memory to regain the renin phenotype when homeostasis is threatened. To perform all of these functions and maintain well-being, renin cells must regulate their identity and fate. Here, we review the major mechanisms that control the differentiation and fate of renin cells, the chromatin events that control the memory of the renin phenotype, and the major pathways that determine their plasticity. We also examine how chronic stimulation of renin cells alters their fate leading to the development of a severe and concentric hypertrophy of the intrarenal arteries and arterioles. Lastly, we provide examples of additional changes in renin cell fate that contribute to equally severe kidney disorders.
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Affiliation(s)
- Maria Luisa S. Sequeira-Lopez
- Departments of Pediatrics an Biology, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - R. Ariel Gomez
- Departments of Pediatrics an Biology, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
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3
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DeLalio LJ, Masati E, Mendu S, Ruddiman CA, Yang Y, Johnstone SR, Milstein JA, Keller TCS, Weaver RB, Guagliardo NA, Best AK, Ravichandran KS, Bayliss DA, Sequeira-Lopez MLS, Sonkusare SN, Shu XH, Desai B, Barrett PQ, Le TH, Gomez RA, Isakson BE. Pannexin 1 channels in renin-expressing cells influence renin secretion and blood pressure homeostasis. Kidney Int 2020; 98:630-644. [PMID: 32446934 PMCID: PMC7483468 DOI: 10.1016/j.kint.2020.04.041] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 03/29/2020] [Accepted: 04/02/2020] [Indexed: 02/07/2023]
Abstract
Kidney function and blood pressure homeostasis are regulated by purinergic signaling mechanisms. These autocrine/paracrine signaling pathways are initiated by the release of cellular ATP, which influences kidney hemodynamics and steady-state renin secretion from juxtaglomerular cells. However, the mechanism responsible for ATP release that supports tonic inputs to juxtaglomerular cells and regulates renin secretion remains unclear. Pannexin 1 (Panx1) channels localize to both afferent arterioles and juxtaglomerular cells and provide a transmembrane conduit for ATP release and ion permeability in the kidney and the vasculature. We hypothesized that Panx1 channels in renin-expressing cells regulate renin secretion in vivo. Using a renin cell-specific Panx1 knockout model, we found that male Panx1 deficient mice exhibiting a heightened activation of the renin-angiotensin-aldosterone system have markedly increased plasma renin and aldosterone concentrations, and elevated mean arterial pressure with altered peripheral hemodynamics. Following ovariectomy, female mice mirrored the male phenotype. Furthermore, constitutive Panx1 channel activity was observed in As4.1 renin-secreting cells, whereby Panx1 knockdown reduced extracellular ATP accumulation, lowered basal intracellular calcium concentrations and recapitulated a hyper-secretory renin phenotype. Moreover, in response to stress stimuli that lower blood pressure, Panx1-deficient mice exhibited aberrant "renin recruitment" as evidenced by reactivation of renin expression in pre-glomerular arteriolar smooth muscle cells. Thus, renin-cell Panx1 channels suppress renin secretion and influence adaptive renin responses when blood pressure homeostasis is threatened.
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Affiliation(s)
- Leon J DeLalio
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA; Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Ester Masati
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Suresh Mendu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Claire A Ruddiman
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA; Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Yang Yang
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA; Department of Pharmacology, Dalian Medical University, Dalian, China
| | - Scott R Johnstone
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Jenna A Milstein
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - T C Stevenson Keller
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA; Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Rachel B Weaver
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Nick A Guagliardo
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Angela K Best
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Kodi S Ravichandran
- Department of Microbiology, Immunology, and Cancer, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Maria Luisa S Sequeira-Lopez
- Pediatric Center of Excellence in Nephrology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Swapnil N Sonkusare
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA; Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Xiaohong H Shu
- Department of Pharmacology, Dalian Medical University, Dalian, China
| | - Bimal Desai
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Paula Q Barrett
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Thu H Le
- Department of Medicine, Division of Nephrology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
| | - R Ariel Gomez
- Pediatric Center of Excellence in Nephrology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Brant E Isakson
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA; Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia, USA.
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4
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Alhenc-Gelas F. A new channel for the control of renin secretion in juxtaglomerular cells. Kidney Int 2020; 98:543-545. [PMID: 32828234 DOI: 10.1016/j.kint.2020.05.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/09/2020] [Accepted: 05/14/2020] [Indexed: 11/25/2022]
Abstract
The role of membrane channels in juxtaglomerular cell physiology is only partially understood. Pannexin 1 is a mechanosensitive, nonjunctional channel known for its role in adenosine triphosphate release. The study by DeLalio et al. documents involvement of pannexin 1 in renin secretion by studying mice deficient in pannexin 1 in renin-secreting cells and a prorenin-secreting cell line. Pannexin 1 is believed to suppress renin secretion and thereby modify blood pressure. The commentary addresses the broader physiological implication of these observations for the regulation of renin and blood pressure.
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Affiliation(s)
- Francois Alhenc-Gelas
- Institut National de la Santé et de la Recherche Médicale U1138-Centre de Recherche des Cordeliers, Paris Universite, Sorbonne Universite, Paris, France.
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