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Arreola J, López-Romero AE, Huerta M, Guzmán-Hernández ML, Pérez-Cornejo P. Insights into the function and regulation of the calcium-activated chloride channel TMEM16A. Cell Calcium 2024; 121:102891. [PMID: 38772195 DOI: 10.1016/j.ceca.2024.102891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 04/23/2024] [Accepted: 04/23/2024] [Indexed: 05/23/2024]
Abstract
The TMEM16A channel, a member of the TMEM16 protein family comprising chloride (Cl-) channels and lipid scramblases, is activated by the free intracellular Ca2+ increments produced by inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release after GqPCRs or Ca2+ entry through cationic channels. It is a ubiquitous transmembrane protein that participates in multiple physiological functions essential to mammals' lives. TMEM16A structure contains two identical 10-segment monomers joined at their transmembrane segment 10. Each monomer harbours one independent hourglass-shaped pore gated by Ca2+ ligation to an orthosteric site adjacent to the pore and controlled by two gates. The orthosteric site is created by assembling negatively charged glutamate side chains near the pore´s cytosolic end. When empty, this site generates an electrostatic barrier that controls channel rectification. In addition, an isoleucine-triad forms a hydrophobic gate at the boundary of the cytosolic vestibule and the inner side of the neck. When the cytosolic Ca2+ rises, one or two Ca2+ ions bind to the orthosteric site in a voltage (V)-dependent manner, thus neutralising the electrostatic barrier and triggering an allosteric gating mechanism propagating via transmembrane segment 6 to the hydrophobic gate. These coordinated events lead to pore opening, allowing the Cl- flux to ensure the physiological response. The Ca2+-dependent function of TMEM16A is highly regulated. Anions with higher permeability than Cl- facilitate V dependence by increasing the Ca2+ sensitivity, intracellular protons can replace Ca2+ and induce channel opening, and phosphatidylinositol 4,5-bisphosphate bound to four cytosolic sites likely maintains Ca2+ sensitivity. Additional regulation is afforded by cytosolic proteins, most likely by phosphorylation and protein-protein interaction mechanisms.
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Affiliation(s)
- Jorge Arreola
- Jorge Arreola, Physics Institute of Universidad Autónoma de San Luis Potosí. Av. Parque Chapultepec 1570, Privadas del Pedregal, 78295 San Luis Potosí, SLP., Mexico.
| | - Ana Elena López-Romero
- Jorge Arreola, Physics Institute of Universidad Autónoma de San Luis Potosí. Av. Parque Chapultepec 1570, Privadas del Pedregal, 78295 San Luis Potosí, SLP., Mexico
| | - Miriam Huerta
- Jorge Arreola, Physics Institute of Universidad Autónoma de San Luis Potosí. Av. Parque Chapultepec 1570, Privadas del Pedregal, 78295 San Luis Potosí, SLP., Mexico
| | - María Luisa Guzmán-Hernández
- Catedrática CONAHCYT, Department of Physiology and Biophysics, School of Medicine, Universidad Autónoma de San Luis Potosí. Ave. V. Carranza 2905, Los Filtros, San Luis Potosí, SLP 78210, Mexico
| | - Patricia Pérez-Cornejo
- Department of Physiology and Biophysics, School of Medicine, Universidad Autónoma de San Luis Potosí. Ave. V. Carranza 2905, Los Filtros, San Luis Potosí, SLP 78210, Mexico
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Arreola J. WNK kinase, ion channels and arachidonic acid metabolites choreographically execute endothelium-dependent vasodilation. Cell Calcium 2024; 121:102904. [PMID: 38728790 DOI: 10.1016/j.ceca.2024.102904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Accepted: 05/04/2024] [Indexed: 05/12/2024]
Abstract
The smooth muscle-walled blood vessels control blood pressure. The vessel lumen is lined by an endothelial cell (ECs) layer, interconnected to the surrounding smooth muscle cells (SMCs) by myoendothelial gap junctions. Gap junctions also maintain homo-cellular ECs-ECs and SMCs-SMCs connections. This gap junction network nearly equalises both cells' membrane potential and cytosolic ionic composition, whether in resting or stimulated conditions. When acetylcholine (ACh) activates ECs M3 receptors, a complex signalling cascade involving second messengers and ion channels is triggered to induce vasodilation.
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Affiliation(s)
- Jorge Arreola
- Physics Institute, Universidad Autónoma de San Luis Potosí, Av. Parque Chapultepec 1570, Privadas del Pedregal, 78295 San Luis Potosí, S.L.P, México.
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Lin WY, Chung WY, Muallem S. The tether function of the anoctamins. Cell Calcium 2024; 121:102875. [PMID: 38701708 DOI: 10.1016/j.ceca.2024.102875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 03/17/2024] [Accepted: 03/20/2024] [Indexed: 05/05/2024]
Abstract
The core functions of the anoctamins are Cl- channel activity and phosphatidylserine (and perhaps other lipids) scrambling. These functions have been extensively studied in various tissues and cells. However, another function of the anoctamins that is less recognized and minimally explored is as tethers at membrane contact sites. This short review aims to examine evidence supporting the localization of the anoctamins at membrane contact sites, their tether properties, and their functions as tethers.
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Affiliation(s)
- Wei-Yin Lin
- From the Epithelial Signaling and Transport Section, National Institute of Dental Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Woo Young Chung
- From the Epithelial Signaling and Transport Section, National Institute of Dental Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shmuel Muallem
- From the Epithelial Signaling and Transport Section, National Institute of Dental Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
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Davis MJ, Zawieja SD. Pacemaking in the lymphatic system. J Physiol 2024. [PMID: 38520402 DOI: 10.1113/jp284752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 02/08/2024] [Indexed: 03/25/2024] Open
Abstract
Lymphatic collecting vessels exhibit spontaneous phasic contractions that are critical for lymph propulsion and tissue fluid homeostasis. This rhythmic activity is driven by action potentials conducted across the lymphatic muscle cell (LMC) layer to produce entrained contractions. The contraction frequency of a lymphatic collecting vessel displays exquisite mechanosensitivity, with a dynamic range from <1 to >20 contractions per minute. A myogenic pacemaker mechanism intrinsic to the LMCs was initially postulated to account for pressure-dependent chronotropy. Further interrogation into the cellular constituents of the lymphatic vessel wall identified non-muscle cell populations that shared some characteristics with interstitial cells of Cajal, which have pacemaker functions in the gastrointestinal and lower urinary tracts, thus raising the possibility of a non-muscle cell pacemaker. However, recent genetic knockout studies in mice support LMCs and a myogenic origin of the pacemaker activity. LMCs exhibit stochastic, but pressure-sensitive, sarcoplasmic reticulum calcium release (puffs and waves) from IP3R1 receptors, which couple to the calcium-activated chloride channel Anoctamin 1, causing depolarisation. The resulting electrical activity integrates across the highly coupled lymphatic muscle electrical syncytia through connexin 45 to modulate diastolic depolarisation. However, multiple other cation channels may also contribute to the ionic pacemaking cycle. Upon reaching threshold, a voltage-gated calcium channel-dependent action potential fires, resulting in a nearly synchronous calcium global calcium flash within the LMC layer to drive an entrained contraction. This review summarizes the key ion channels potentially responsible for the pressure-dependent chronotropy of lymphatic collecting vessels and various mechanisms of IP3R1 regulation that could contribute to frequency tuning.
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Affiliation(s)
- Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, USA
| | - Scott D Zawieja
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, USA
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Al-Hosni R, Kaye R, Choi CS, Tammaro P. The TMEM16A channel as a potential therapeutic target in vascular disease. Curr Opin Nephrol Hypertens 2024; 33:161-169. [PMID: 38193301 PMCID: PMC10842660 DOI: 10.1097/mnh.0000000000000967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
PURPOSE OF REVIEW The transmembrane protein 16A (TMEM16A) Ca 2+ -activated Cl - channel constitutes a key depolarising mechanism in vascular smooth muscle and contractile pericytes, while in endothelial cells the channel is implicated in angiogenesis and in the response to vasoactive stimuli. Here, we offer a critical analysis of recent physiological investigations and consider the potential for targeting TMEM16A channels in vascular disease. RECENT FINDINGS Genetic deletion or pharmacological inhibition of TMEM16A channels in vascular smooth muscle decreases artery tone and lowers systemic blood pressure in rodent models. Inhibition of TMEM16A channels in cerebral cortical pericytes protects against ischemia-induced tissue damage and improves microvascular blood flow in rodent stroke models. In endothelial cells, the TMEM16A channel plays varied roles including modulation of cell division and control of vessel tone through spread of hyperpolarisation to the smooth muscle cells. Genetic studies implicate TMEM16A channels in human disease including systemic and pulmonary hypertension, stroke and Moyamoya disease. SUMMARY The TMEM16A channel regulates vascular function by controlling artery tone and capillary diameter as well as vessel formation and histology. Preclinical and clinical investigations are highlighting the potential for therapeutic exploitation of the channel in a range of maladaptive states of the (micro)circulation.
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Affiliation(s)
- Rumaitha Al-Hosni
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, UK
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Lu P, Lifshitz LM, Bellve K, ZhuGe R. TMEM16A in smooth muscle cells acts as a pacemaker channel in the internal anal sphincter. Commun Biol 2024; 7:151. [PMID: 38317010 PMCID: PMC10844222 DOI: 10.1038/s42003-024-05850-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 01/23/2024] [Indexed: 02/07/2024] Open
Abstract
Maintenance of fecal continence requires a continuous or basal tone of the internal anal sphincter (IAS). Paradoxically, the basal tone results largely from high-frequency rhythmic contractions of the IAS smooth muscle. However, the cellular and molecular mechanisms that initiate these contractions remain elusive. Here we show that the IAS contains multiple pacemakers. These pacemakers spontaneously generate propagating calcium waves that drive rhythmic contractions and establish the basal tone. These waves are myogenic and act independently of nerve, paracrine or autocrine signals. Using cell-specific gene knockout mice, we further found that TMEM16A Cl- channels in smooth muscle cells (but not in the interstitial cells of Cajal) are indispensable for pacemaking, rhythmic contractions, and basal tone. Our results identify TMEM16A in smooth muscle cells as a critical pacemaker channel that enables the IAS to contract rhythmically and continuously. This study provides cellular and molecular insights into fecal continence.
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Affiliation(s)
- Ping Lu
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Lawrence M Lifshitz
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Karl Bellve
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Ronghua ZhuGe
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA, USA.
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Grainger N. Identifying peristaltic pacemaker cells in the upper urinary tract. J Physiol 2024. [PMID: 38180778 DOI: 10.1113/jp284754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 12/18/2023] [Indexed: 01/06/2024] Open
Abstract
Urine expulsion from the upper urinary tract is a necessary process that eliminates waste, promotes renal filtration and prevents nephron damage. To facilitate the movement of urine boluses throughout the upper urinary tract, smooth muscle cells that line the renal pelvis contract in a coordinated effort to form peristaltic waves. Resident pacemaker cells in the renal pelvis are critical to this process and spontaneously evoke transient depolarizations that initiate each peristaltic wave and establish rhythmic contractions. Renal pacemakers have been termed atypical smooth muscle cells due to their low expression of smooth muscle myosin and poor organization of myofilaments compared to typical (or contractile) smooth muscle cells that perform peristalsis. Recent findings discovered that pacemaker cells also express the tyrosine kinase receptor PDGFRα, enabling their identification and purification amongst other renal pelvis cell types. Improved identification methods have determined that the calcium-activated chloride channel, ANO1, is expressed by pacemaker cells and may contribute to spontaneous depolarization. A greater understanding of pacemaker and peristaltic mechanisms is warranted since aberrant contractile function may underlie diseases such as hydronephrosis, a deleterious condition that can cause significant and irreversible nephron injury.
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Affiliation(s)
- Nathan Grainger
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada, USA
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Zawieja SD, Pea GA, Broyhill SE, Patro A, Bromert KH, Li M, Norton CE, Castorena-Gonzalez JA, Hancock EJ, Bertram CD, Davis MJ. IP3R1 underlies diastolic ANO1 activation and pressure-dependent chronotropy in lymphatic collecting vessels. J Gen Physiol 2023; 155:e202313358. [PMID: 37851027 PMCID: PMC10585095 DOI: 10.1085/jgp.202313358] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 08/11/2023] [Accepted: 09/22/2023] [Indexed: 10/19/2023] Open
Abstract
Pressure-dependent chronotropy of murine lymphatic collecting vessels relies on the activation of the Ca2+-activated chloride channel encoded by Anoctamin 1 (Ano1) in lymphatic muscle cells. Genetic ablation or pharmacological inhibition of ANO1 results in a significant reduction in basal contraction frequency and essentially complete loss of pressure-dependent frequency modulation by decreasing the rate of the diastolic depolarization phase of the ionic pacemaker in lymphatic muscle cells (LMCs). Oscillating Ca2+ release from sarcoendoplasmic reticulum Ca2+ channels has been hypothesized to drive ANO1 activity during diastole, but the source of Ca2+ for ANO1 activation in smooth muscle remains unclear. Here, we investigated the role of the inositol triphosphate receptor 1 (Itpr1; Ip3r1) in this process using pressure myography, Ca2+ imaging, and membrane potential recordings in LMCs of ex vivo pressurized inguinal-axillary lymphatic vessels from control or Myh11CreERT2;Ip3r1fl/fl (Ip3r1ismKO) mice. Ip3r1ismKO vessels had significant reductions in contraction frequency and tone but an increased contraction amplitude. Membrane potential recordings from LMCs of Ip3r1ismKO vessels revealed a depressed diastolic depolarization rate and an elongation of the plateau phase of the action potential (AP). Ca2+ imaging of LMCs using the genetically encoded Ca2+ sensor GCaMP6f demonstrated an elongation of the Ca2+ flash associated with an AP-driven contraction. Critically, diastolic subcellular Ca2+ transients were absent in LMCs of Ip3r1ismKO mice, demonstrating the necessity of IP3R1 activity in controlling ANO1-mediated diastolic depolarization. These findings indicate a critical role for IP3R1 in lymphatic vessel pressure-dependent chronotropy and contractile regulation.
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Affiliation(s)
- Scott D. Zawieja
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
| | - Grace A. Pea
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
| | - Sarah E. Broyhill
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
| | - Advaya Patro
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
| | - Karen H. Bromert
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
| | - Min Li
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
| | - Charles E. Norton
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
| | | | - Edward J. Hancock
- School of Mathematics and Statistics, University of Sydney, Sydney, Australia
| | | | - Michael J. Davis
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
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