1
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Garrud TAC, Bell B, Mata-Daboin A, Peixoto-Neves D, Collier DM, Cordero-Morales JF, Jaggar JH. WNK kinase is a vasoactive chloride sensor in endothelial cells. Proc Natl Acad Sci U S A 2024; 121:e2322135121. [PMID: 38568964 PMCID: PMC11009681 DOI: 10.1073/pnas.2322135121] [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: 12/21/2023] [Accepted: 03/01/2024] [Indexed: 04/05/2024] Open
Abstract
Endothelial cells (ECs) line the wall of blood vessels and regulate arterial contractility to tune regional organ blood flow and systemic pressure. Chloride (Cl-) is the most abundant anion in ECs and the Cl- sensitive With-No-Lysine (WNK) kinase is expressed in this cell type. Whether intracellular Cl- signaling and WNK kinase regulate EC function to alter arterial contractility is unclear. Here, we tested the hypothesis that intracellular Cl- signaling in ECs regulates arterial contractility and examined the signaling mechanisms involved, including the participation of WNK kinase. Our data obtained using two-photon microscopy and cell-specific inducible knockout mice indicated that acetylcholine, a prototypical vasodilator, stimulated a rapid reduction in intracellular Cl- concentration ([Cl-]i) due to the activation of TMEM16A, a Cl- channel, in ECs of resistance-size arteries. TMEM16A channel-mediated Cl- signaling activated WNK kinase, which phosphorylated its substrate proteins SPAK and OSR1 in ECs. OSR1 potentiated transient receptor potential vanilloid 4 (TRPV4) currents in a kinase-dependent manner and required a conserved binding motif located in the channel C terminus. Intracellular Ca2+ signaling was measured in four dimensions in ECs using a high-speed lightsheet microscope. WNK kinase-dependent activation of TRPV4 channels increased local intracellular Ca2+ signaling in ECs and produced vasodilation. In summary, we show that TMEM16A channel activation reduces [Cl-]i, which activates WNK kinase in ECs. WNK kinase phosphorylates OSR1 which then stimulates TRPV4 channels to produce vasodilation. Thus, TMEM16A channels regulate intracellular Cl- signaling and WNK kinase activity in ECs to control arterial contractility.
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Affiliation(s)
- Tessa A. C. Garrud
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN38163
| | - Briar Bell
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN38163
- Department of Biochemistry and Molecular Biology, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX77030
| | - Alejandro Mata-Daboin
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN38163
| | | | - Daniel M. Collier
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, TN38163
| | - Julio F. Cordero-Morales
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN38163
- Department of Biochemistry and Molecular Biology, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX77030
| | - Jonathan H. Jaggar
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN38163
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2
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Romero LO, Caires R, Kaitlyn Victor A, Ramirez J, Sierra-Valdez FJ, Walsh P, Truong V, Lee J, Mayor U, Reiter LT, Vásquez V, Cordero-Morales JF. Linoleic acid improves PIEZO2 dysfunction in a mouse model of Angelman Syndrome. Nat Commun 2023; 14:1167. [PMID: 36859399 PMCID: PMC9977963 DOI: 10.1038/s41467-023-36818-0] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 02/17/2023] [Indexed: 03/03/2023] Open
Abstract
Angelman syndrome (AS) is a neurogenetic disorder characterized by intellectual disability and atypical behaviors. AS results from loss of expression of the E3 ubiquitin-protein ligase UBE3A from the maternal allele in neurons. Individuals with AS display impaired coordination, poor balance, and gait ataxia. PIEZO2 is a mechanosensitive ion channel essential for coordination and balance. Here, we report that PIEZO2 activity is reduced in Ube3a deficient male and female mouse sensory neurons, a human Merkel cell carcinoma cell line and female human iPSC-derived sensory neurons with UBE3A knock-down, and de-identified stem cell-derived neurons from individuals with AS. We find that loss of UBE3A decreases actin filaments and reduces PIEZO2 expression and function. A linoleic acid (LA)-enriched diet increases PIEZO2 activity, mechano-excitability, and improves gait in male AS mice. Finally, LA supplementation increases PIEZO2 function in stem cell-derived neurons from individuals with AS. We propose a mechanism whereby loss of UBE3A expression reduces PIEZO2 function and identified a fatty acid that enhances channel activity and ameliorates AS-associated mechano-sensory deficits.
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Affiliation(s)
- Luis O Romero
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38103, USA
- Integrated Biomedical Sciences Graduate Program, College of Graduate Health Sciences, Memphis, TN, 38163, USA
| | - Rebeca Caires
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38103, USA
| | - A Kaitlyn Victor
- Department of Neurology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38103, USA
| | - Juanma Ramirez
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, UPV/EHU, Leioa, Bizkaia, Spain
| | - Francisco J Sierra-Valdez
- School of Engineering and Sciences, Tecnológico de Monterrey, Ave. Eugenio Garza Sada 2501 Sur, Monterrey, 64849, Mexico
| | | | | | - Jungsoo Lee
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38103, USA
| | - Ugo Mayor
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, UPV/EHU, Leioa, Bizkaia, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Bizkaia, Spain
| | - Lawrence T Reiter
- Department of Neurology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38103, USA
- Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38104, USA
- Department of Pediatrics, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38104, USA
| | - Valeria Vásquez
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38103, USA.
| | - Julio F Cordero-Morales
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38103, USA.
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3
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Caires R, Garrud TAC, Romero LO, Fernández-Peña C, Vásquez V, Jaggar JH, Cordero-Morales JF. Genetic- and diet-induced ω-3 fatty acid enrichment enhances TRPV4-mediated vasodilation in mice. Cell Rep 2022; 40:111306. [PMID: 36070688 PMCID: PMC9498980 DOI: 10.1016/j.celrep.2022.111306] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 07/05/2022] [Accepted: 08/11/2022] [Indexed: 11/19/2022] Open
Abstract
TRPV4 channel activation in endothelial cells leads to vasodilation, while impairment of TRPV4 activity is implicated in vascular dysfunction. Strategies that increase TRPV4 activity could enhance vasodilation and ameliorate vascular disorders. Here, we show that supplementation with eicosapentaenoic acid (EPA), an ω-3 polyunsaturated fatty acid known to have beneficial cardiovascular effects, increases TRPV4 activity in human endothelial cells of various vascular beds. Mice carrying the C. elegans FAT-1 enzyme, which converts ω-6 to ω-3 polyunsaturated fatty acids, display higher EPA content and increased TRPV4-mediated vasodilation in mesenteric arteries. Likewise, mice fed an EPA-enriched diet exhibit enhanced and prolonged TRPV4-dependent vasodilation in an endothelial cell-specific manner. We also show that EPA supplementation reduces TRPV4 desensitization, which contributes to the prolonged vasodilation. Neutralization of positive charges in the TRPV4 N terminus impairs the effect of EPA on channel desensitization. These findings highlight the beneficial effects of manipulating fatty acid content to enhance TRPV4-mediated vasodilation.
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Affiliation(s)
- Rebeca Caires
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Tessa A C Garrud
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Luis O Romero
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA; Integrated Biomedical Sciences Graduate Program, College of Graduate Health Sciences, Memphis, TN 38163, USA
| | - Carlos Fernández-Peña
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Valeria Vásquez
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Jonathan H Jaggar
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Julio F Cordero-Morales
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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4
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Caires Mugarra R, Garrud T, Fernández-Peña C, Saha S, Moreno CM, Vasquez V, Jaggar JH, Cordero-Morales JF, Romero LO. Genetic- and diet-induced omega 3 fatty acid enrichment reduces TRPV4 desensitization in endothelial cells to enhance vasodilation. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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5
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Bell B, Meena A, Shukla P, Caires Mugarra R, Fernández-Peña C, Vasquez V, Jaggar JH, Cordero-Morales JF, Rao R. TRPV6 mediates alcohol-induced gut barrier dysfunction. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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6
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Zhang S, Romero LO, Deng S, Wang J, Li Y, Yang L, Hamilton DJ, Miller DD, Liao FF, Cordero-Morales JF, Wu Z, Li W. Discovery of a Highly Selective and Potent TRPC3 Inhibitor with High Metabolic Stability and Low Toxicity. ACS Med Chem Lett 2021; 12:572-578. [PMID: 33859797 PMCID: PMC8040052 DOI: 10.1021/acsmedchemlett.0c00571] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [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: 11/02/2020] [Accepted: 02/26/2021] [Indexed: 12/21/2022] Open
Abstract
The overactivation of transient receptor potential canonical 3 (TRPC3) is associated with neurodegenerative diseases and hypertension. Pyrazole 3 (Pyr3) is reported as the most selective TRPC3 inhibitor, but it has two inherent structural limitations: (1) the labile ester moiety leads to its rapid hydrolysis to the inactive Pyr8 in vivo, and (2) the alkylating trichloroacrylic amide moiety is known to be toxic. To circumvent these limitations, we designed a series of conformationally restricted Pyr3 analogues and reported that compound 20 maintains high potency and selectivity for human TRPC3 over its closely related TRP channels. It has significantly improved metabolic stability compared with Pyr3 and has a good safety profile. Preliminary evaluation of 20 demonstrated its ability to rescue Aβ-induced neuron damage with similar potency to that of Pyr3 in vitro. Collectively, these results suggest that 20 represents a promising scaffold to potentially ameliorate the symptoms associated with TRPC3-mediated neurological and cardiovascular disorders.
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Affiliation(s)
- Sicheng Zhang
- Department
of Pharmaceutical Sciences, College of Pharmacy, the University of Tennessee Health Science Center, Memphis, Tennessee 38163, United States
| | - Luis O. Romero
- Department
of Physiology, the University of Tennessee
Health Science Center, Memphis, Tennessee 38163, United States
- Integrated
Biomedical Sciences Graduate Program, College
of Graduate Health Sciences, Memphis, Tennessee 38163, United States
| | - Shanshan Deng
- Department
of Pharmaceutical Sciences, College of Pharmacy, the University of Tennessee Health Science Center, Memphis, Tennessee 38163, United States
| | - Jiaxing Wang
- Department
of Pharmaceutical Sciences, College of Pharmacy, the University of Tennessee Health Science Center, Memphis, Tennessee 38163, United States
| | - Yong Li
- Department
of Chemical Biology and Therapeutics, St.
Jude Children’s Research Hospital, Memphis, Tennessee 38105, United States
| | - Lei Yang
- Department
of Chemical Biology and Therapeutics, St.
Jude Children’s Research Hospital, Memphis, Tennessee 38105, United States
| | - David J. Hamilton
- Department
of Comparative Medicine, College of Graduate Health Sciences, the University of Tennessee Health Science Center, Memphis, Tennessee 38163, United States
| | - Duane D. Miller
- Department
of Pharmaceutical Sciences, College of Pharmacy, the University of Tennessee Health Science Center, Memphis, Tennessee 38163, United States
| | - Francesca-Fang Liao
- Department
of Pharmacology, Addiction Science, and Toxicology, the University of Tennessee Health Science Center, Memphis, Tennessee 38163, United States
| | - Julio F. Cordero-Morales
- Department
of Physiology, the University of Tennessee
Health Science Center, Memphis, Tennessee 38163, United States
| | - Zhongzhi Wu
- Department
of Pharmaceutical Sciences, College of Pharmacy, the University of Tennessee Health Science Center, Memphis, Tennessee 38163, United States
| | - Wei Li
- Department
of Pharmaceutical Sciences, College of Pharmacy, the University of Tennessee Health Science Center, Memphis, Tennessee 38163, United States
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7
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Romero LO, Caires R, Nickolls AR, Chesler AT, Cordero-Morales JF, Vásquez V. A dietary fatty acid counteracts neuronal mechanical sensitization. Nat Commun 2020; 11:2997. [PMID: 32561714 PMCID: PMC7305179 DOI: 10.1038/s41467-020-16816-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 05/26/2020] [Indexed: 02/06/2023] Open
Abstract
PIEZO2 is the essential transduction channel for touch discrimination, vibration, and proprioception. Mice and humans lacking Piezo2 experience severe mechanosensory and proprioceptive deficits and fail to develop tactile allodynia. Bradykinin, a proalgesic agent released during inflammation, potentiates PIEZO2 activity. Molecules that decrease PIEZO2 function could reduce heightened touch responses during inflammation. Here, we find that the dietary fatty acid margaric acid (MA) decreases PIEZO2 function in a dose-dependent manner. Chimera analyses demonstrate that the PIEZO2 beam is a key region tuning MA-mediated channel inhibition. MA reduces neuronal action potential firing elicited by mechanical stimuli in mice and rat neurons and counteracts PIEZO2 sensitization by bradykinin. Finally, we demonstrate that this saturated fatty acid decreases PIEZO2 currents in touch neurons derived from human induced pluripotent stem cells. Our findings report on a natural product that inhibits PIEZO2 function and counteracts neuronal mechanical sensitization and reveal a key region for channel inhibition.
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Affiliation(s)
- Luis O Romero
- 71S. Manassas St. Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38103, USA
- Integrated Biomedical Sciences Graduate Program, College of Graduate Health Sciences, Memphis, TN, 38103, USA
| | - Rebeca Caires
- 71S. Manassas St. Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38103, USA
| | - Alec R Nickolls
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, 20892, USA
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Alexander T Chesler
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD, 20892, USA.
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Julio F Cordero-Morales
- 71S. Manassas St. Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38103, USA.
| | - Valeria Vásquez
- 71S. Manassas St. Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38103, USA.
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8
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Nikolaev Y, Cox CD, Ridone P, Rohde PR, Cordero-Morales JF, Vasquez V, Laver DR, Martinac B. Mammalian TRP Ion Channels are Insensitive to Membrane Stretch. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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9
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Vasquez V, Caires Mugarra R, Bell B, Lee J, Cordero-Morales JF. Inhibition of Inositol Monophosphatase Enhances TRPV1 Function in vivo. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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10
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Romero LO, Cordero-Morales JF, Vasquez V. Margaric Acid Decreases Sensory Neurons Mechanical Excitability by Inhibiting PIEZO2 Channels. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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11
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Garcia-Maldonado E, Sierra Valdez FJ, Vasquez V, Cordero-Morales JF. Expression and Purification of a Mammalian TRPV4 for Functional and Structural Analyses. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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12
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Nikolaev YA, Cox CD, Ridone P, Rohde PR, Cordero-Morales JF, Vásquez V, Laver DR, Martinac B. Mammalian TRP ion channels are insensitive to membrane stretch. J Cell Sci 2019; 132:jcs238360. [PMID: 31722978 PMCID: PMC6918743 DOI: 10.1242/jcs.238360] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 10/29/2019] [Indexed: 12/27/2022] Open
Abstract
TRP channels of the transient receptor potential ion channel superfamily are involved in a wide variety of mechanosensory processes, including touch sensation, pain, blood pressure regulation, bone loading and detection of cerebrospinal fluid flow. However, in many instances it is unclear whether TRP channels are the primary transducers of mechanical force in these processes. In this study, we tested stretch activation of eleven TRP channels from six mammalian subfamilies. We found that these TRP channels were insensitive to short membrane stretches in cellular systems. Furthermore, we purified TRPC6 and demonstrated its insensitivity to stretch in liposomes, an artificial bilayer system free from cellular components. Additionally, we demonstrated that, when expressed in C. elegans neurons, mouse TRPC6 restores the mechanoresponse of a touch insensitive mutant but requires diacylglycerol for activation. These results strongly suggest that the mammalian members of the TRP ion channel family are insensitive to tension induced by cell membrane stretching and, thus, are more likely to be activated by cytoplasmic tethers or downstream components and to act as amplifiers of cellular mechanosensory signaling cascades.
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Affiliation(s)
- Yury A Nikolaev
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney 2010, Australia
- Human Physiology, School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle 2308, Australia
| | - Charles D Cox
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney 2010, Australia
| | - Pietro Ridone
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney 2010, Australia
| | - Paul R Rohde
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney 2010, Australia
| | - Julio F Cordero-Morales
- Department of Physiology, College of Medicine, The University of Tennessee Health Science Center, Memphis 38163, USA
| | - Valeria Vásquez
- Department of Physiology, College of Medicine, The University of Tennessee Health Science Center, Memphis 38163, USA
| | - Derek R Laver
- Human Physiology, School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle 2308, Australia
| | - Boris Martinac
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney 2010, Australia
- St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney 2052, Australia
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13
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Romero LO, Massey AE, Mata-Daboin AD, Sierra-Valdez FJ, Chauhan SC, Cordero-Morales JF, Vásquez V. Dietary fatty acids fine-tune Piezo1 mechanical response. Nat Commun 2019; 10:1200. [PMID: 30867417 PMCID: PMC6416271 DOI: 10.1038/s41467-019-09055-7] [Citation(s) in RCA: 134] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 02/18/2019] [Indexed: 12/18/2022] Open
Abstract
Mechanosensitive ion channels rely on membrane composition to transduce physical stimuli into electrical signals. The Piezo1 channel mediates mechanoelectrical transduction and regulates crucial physiological processes, including vascular architecture and remodeling, cell migration, and erythrocyte volume. The identity of the membrane components that modulate Piezo1 function remain largely unknown. Using lipid profiling analyses, we here identify dietary fatty acids that tune Piezo1 mechanical response. We find that margaric acid, a saturated fatty acid present in dairy products and fish, inhibits Piezo1 activation and polyunsaturated fatty acids (PUFAs), present in fish oils, modulate channel inactivation. Force measurements reveal that margaric acid increases membrane bending stiffness, whereas PUFAs decrease it. We use fatty acid supplementation to abrogate the phenotype of gain-of-function Piezo1 mutations causing human dehydrated hereditary stomatocytosis. Beyond Piezo1, our findings demonstrate that cell-intrinsic lipid profile and changes in the fatty acid metabolism can dictate the cell's response to mechanical cues.
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Affiliation(s)
- Luis O Romero
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, 71S. Manassas St., Memphis, TN, 38163, USA
| | - Andrew E Massey
- Department of Pharmaceutical Sciences and Institute of Biomarker and Molecular Therapeutics (IBMT), College of Pharmacy, University of Tennessee Health Science Center, 881 Madison Ave., Memphis, TN, 38163, USA
| | - Alejandro D Mata-Daboin
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, 71S. Manassas St., Memphis, TN, 38163, USA
| | - Francisco J Sierra-Valdez
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, 71S. Manassas St., Memphis, TN, 38163, USA
- Centro de Investigación Biomédica, Hospital Zambrano Hellion, TecSalud, Ave. Batallon de San Patricio 112, 66278, San Pedro Garza García, Nuevo León, Mexico
- Tecnólogico de Monterrey, Escuela de Ingeniería y Ciencias, Ave. Eugenio Garza Sada 2501 Sur, 64849, Monterrey, Nuevo León, Mexico
| | - Subhash C Chauhan
- Department of Pharmaceutical Sciences and Institute of Biomarker and Molecular Therapeutics (IBMT), College of Pharmacy, University of Tennessee Health Science Center, 881 Madison Ave., Memphis, TN, 38163, USA
| | - Julio F Cordero-Morales
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, 71S. Manassas St., Memphis, TN, 38163, USA
| | - Valeria Vásquez
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, 71S. Manassas St., Memphis, TN, 38163, USA.
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14
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Sierra Valdez FJ, Azumaya CM, Romero LO, Nakagawa T, Cordero-Morales JF. Structural and Functional Analyses of TRPC3 Reveal Allosteric Gating Modulation by the Cytoplasmic Domain. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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15
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Sierra-Valdez F, Azumaya CM, Romero LO, Nakagawa T, Cordero-Morales JF. Structure-function analyses of the ion channel TRPC3 reveal that its cytoplasmic domain allosterically modulates channel gating. J Biol Chem 2018; 293:16102-16114. [PMID: 30139744 DOI: 10.1074/jbc.ra118.005066] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [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: 07/25/2018] [Revised: 08/17/2018] [Indexed: 12/14/2022] Open
Abstract
The transient receptor potential ion channels support Ca2+ permeation in many organs, including the heart, brain, and kidney. Genetic mutations in transient receptor potential cation channel subfamily C member 3 (TRPC3) are associated with neurodegenerative diseases, memory loss, and hypertension. To better understand the conformational changes that regulate TRPC3 function, we solved the cryo-EM structures for the full-length human TRPC3 and its cytoplasmic domain (CPD) in the apo state at 5.8- and 4.0-Å resolution, respectively. These structures revealed that the TRPC3 transmembrane domain resembles those of other TRP channels and that the CPD is a stable module involved in channel assembly and gating. We observed the presence of a C-terminal domain swap at the center of the CPD where horizontal helices (HHs) transition into a coiled-coil bundle. Comparison of TRPC3 structures revealed that the HHs can reside in two distinct positions. Electrophysiological analyses disclosed that shortening the length of the C-terminal loop connecting the HH with the TRP helices increases TRPC3 activity and that elongating the length of the loop has the opposite effect. Our findings indicate that the C-terminal loop affects channel gating by altering the allosteric coupling between the cytoplasmic and transmembrane domains. We propose that molecules that target the HH may represent a promising strategy for controlling TRPC3-associated neurological disorders and hypertension.
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Affiliation(s)
- Francisco Sierra-Valdez
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163 and
| | | | - Luis O Romero
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163 and
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, .,Center for Structural Biology, and.,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Julio F Cordero-Morales
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163 and
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16
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Cordero-Morales JF, Vásquez V. How lipids contribute to ion channel function, a fat perspective on direct and indirect interactions. Curr Opin Struct Biol 2018; 51:92-98. [PMID: 29602157 PMCID: PMC6162190 DOI: 10.1016/j.sbi.2018.03.015] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [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: 11/03/2017] [Revised: 03/07/2018] [Accepted: 03/15/2018] [Indexed: 11/30/2022]
Abstract
Membrane lipid composition and remodeling influence the function of ion channels. Polyunsaturated fatty acids (PUFAs) and their derivatives modulate ion channel function; whether this effect occurs directly by binding to the protein or indirectly through alteration of membranes' mechanical properties has been difficult to distinguish. There are a large number of studies addressing the effect of fatty acids; recent structural and functional analyses have identified binding sites and provided further evidence for the role of the plasma membrane in ion channel function. Here, we review cation channels that do not share a common topology or lipid-binding signature sequence, but for which there are recent compelling data that support both direct and indirect modulation by PUFAs or their derivatives.
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Affiliation(s)
- Julio F Cordero-Morales
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Valeria Vásquez
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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Sierra-Valdez FJ, Stein RA, Velissety P, Vasquez V, Cordero-Morales JF. Purification and Reconstitution of TRPV1 for Spectroscopic Analysis. J Vis Exp 2018. [PMID: 30035769 DOI: 10.3791/57796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Polymodal ion channels transduce multiple stimuli of different natures into allosteric changes; these dynamic conformations are challenging to determine and remain largely unknown. With recent advances in single-particle cryo-electron microscopy (cryo-EM) shedding light on the structural features of agonist binding sites and the activation mechanism of several ion channels, the stage is set for an in-depth dynamic analysis of their gating mechanisms using spectroscopic approaches. Spectroscopic techniques such as electron paramagnetic resonance (EPR) and double electron-electron resonance (DEER) have been mainly restricted to the study of prokaryotic ion channels that can be purified in large quantities. The requirement for large amounts of functional and stable membrane proteins has hampered the study of mammalian ion channels using these approaches. EPR and DEER offer many advantages, including determination of the structure and dynamic changes of mobile protein regions, albeit at low resolution, that might be difficult to obtain by X-ray crystallography or cryo-EM, and monitoring reversible gating transition (i.e., closed, open, sensitized, and desensitized). Here, we provide protocols for obtaining milligrams of functional detergent-solubilized transient receptor potential cation channel subfamily V member 1 (TRPV1) that can be labeled for EPR and DEER spectroscopy.
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Affiliation(s)
| | - Richard A Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center
| | - Phanindra Velissety
- Department of Physiology, University of Tennessee Health Science Center; CuriRX, Inc
| | - Valeria Vasquez
- Department of Physiology, University of Tennessee Health Science Center
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Azumaya CM, Sierra-Valdez F, Cordero-Morales JF, Nakagawa T. Cryo-EM structure of the cytoplasmic domain of murine transient receptor potential cation channel subfamily C member 6 (TRPC6). J Biol Chem 2018; 293:10381-10391. [PMID: 29752403 PMCID: PMC6028952 DOI: 10.1074/jbc.ra118.003183] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [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: 03/29/2018] [Revised: 05/08/2018] [Indexed: 01/08/2023] Open
Abstract
The kidney maintains the internal milieu by regulating the retention and excretion of proteins, ions, and small molecules. The glomerular podocyte forms the slit diaphragm of the ultrafiltration filter, whose damage leads to progressive kidney failure and focal segmental glomerulosclerosis (FSGS). The canonical transient receptor potential 6 (TRPC6) ion channel is expressed in the podocyte, and mutations in its cytoplasmic domain cause FSGS in humans. In vitro evaluation of disease-causing mutations in TRPC6 has revealed that these genetic alterations result in abnormal ion channel gating. However, the mechanism whereby the cytoplasmic domain modulates TRPC6 function is largely unknown. Here, we report a cryo-EM structure of the cytoplasmic domain of murine TRPC6 at 3.8 Å resolution. The cytoplasmic fold of TRPC6 is characterized by an inverted dome-like chamber pierced by four radial horizontal helices that converge into a vertical coiled-coil at the central axis. Unlike other TRP channels, TRPC6 displays a unique domain swap that occurs at the junction of the horizontal helices and coiled-coil. Multiple FSGS mutations converge at the buried interface between the vertical coiled-coil and the ankyrin repeats, which form the dome, suggesting these regions are critical for allosteric gating modulation. This functionally critical interface is a potential target for drug design. Importantly, dysfunction in other family members leads to learning deficits (TRPC1/4/5) and ataxia (TRPC3). Our data provide a structural framework for the mechanistic investigation of the TRPC family.
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Affiliation(s)
| | - Francisco Sierra-Valdez
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Julio F Cordero-Morales
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Terunaga Nakagawa
- From the Department of Molecular Physiology and Biophysics,
- Center for Structural Biology, and
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232 and
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Romero LO, Cordero-Morales JF, Vásquez V. Electrophysiological Characterization of Mechano-Activated Currents in Human Endothelial Cells. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Caires R, Sierra-Valdez FJ, Millet JR, Herwig JD, Roan E, Vásquez V, Cordero-Morales JF. Omega-3 Fatty Acids Modulate TRPV4 Function through Plasma Membrane Remodeling. Cell Rep 2017; 21:246-258. [DOI: 10.1016/j.celrep.2017.09.029] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 07/18/2017] [Accepted: 09/07/2017] [Indexed: 12/26/2022] Open
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21
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Caires RC, Vasquez V, Cordero-Morales JF. Novel Role of PUFAs as Essential Cofactors for TRPV4 Function. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.2203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Vasquez V, Velisetty P, Cordero-Morales JF. Studying the Effects of Bioactive Lipids on TRPV4 Activation. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.1552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Cao E, Cordero-Morales JF, Liu B, Qin F, Julius D. TRPV1 channels are intrinsically heat sensitive and negatively regulated by phosphoinositide lipids. Neuron 2013; 77:667-79. [PMID: 23439120 DOI: 10.1016/j.neuron.2012.12.016] [Citation(s) in RCA: 232] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2012] [Indexed: 01/20/2023]
Abstract
The capsaicin receptor, TRPV1, is regulated by phosphatidylinositol-4,5-bisphosphate (PIP(2)), although the precise nature of this effect (i.e., positive or negative) remains controversial. Here, we reconstitute purified TRPV1 into artificial liposomes, where it is gated robustly by capsaicin, protons, spider toxins, and, notably, heat, demonstrating intrinsic sensitivity of the channel to both chemical and thermal stimuli. TRPV1 is fully functional in the absence of phosphoinositides, arguing against their proposed obligatory role in channel activation. Rather, introduction of various phosphoinositides, including PIP(2), PI4P, and phosphatidylinositol, inhibits TRPV1, supporting a model whereby phosphoinositide turnover contributes to thermal hyperalgesia by disinhibiting the channel. Using an orthogonal chemical strategy, we show that association of the TRPV1 C terminus with the bilayer modulates channel gating, consistent with phylogenetic data implicating this domain as a key regulatory site for tuning stimulus sensitivity. Beyond TRPV1, these findings are relevant to understanding how membrane lipids modulate other "receptor-operated" TRP channels.
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Affiliation(s)
- Erhu Cao
- Department of Physiology, University of California, San Francisco, CA 94158, USA
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Cao E, Cordero-Morales JF, Liu B, Qin F, Julius D. TRPV1 Channels are Intrinsically Heat Sensitive and Negatively Regulated by Phosphoinositide Lipids. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.2105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Gracheva EO, Cordero-Morales JF, González-Carcacóa JA, Ingolia NT, Manno M, Aranguren CI, Weissman JS, Julius D. Ganglion-Specific Splicing of TRPV1 Underlies Infrared Sensation in Vampire Bats. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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26
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Cordero-Morales JF, Gracheva EO, Julius D. Cytoplasmic Ankyrin Repeats of Transient Receptor Potential A1 (TRPA1) Dictate Sensitivity to Thermal and Chemical Stimuli. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.151] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Ferrer T, Cordero-Morales JF, Arias M, Ficker E, Medovoy D, Perozo E, Tristani-Firouzi M. Molecular coupling in the human ether-a-go-go-related gene-1 (hERG1) K+ channel inactivation pathway. J Biol Chem 2011; 286:39091-9. [PMID: 21908602 PMCID: PMC3234734 DOI: 10.1074/jbc.m111.292060] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [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: 08/09/2011] [Revised: 09/05/2011] [Indexed: 01/30/2023] Open
Abstract
Emerging evidence suggests that K(+) channel inactivation involves coupling between residues in adjacent regions of the channel. Human ether-a-go-go-related gene-1 (hERG1) K(+) channels undergo a fast inactivation gating process that is crucial for maintaining electrical stability in the heart. The molecular mechanisms that drive inactivation in hERG1 channels are unknown. Using alanine scanning mutagenesis, we show that a pore helix residue (Thr-618) that points toward the S5 segment is critical for normal inactivation gating. Amino acid substitutions at position 618 modulate the free energy of inactivation gating, causing enhanced or reduced inactivation. Mutation of an S5 residue that is predicted to be adjacent to Thr-618 (W568L) abolishes inactivation and alters ion selectivity. The introduction of the Thr-618-equivalent residue in Kv1.5 enhances inactivation. Molecular dynamic simulations of the Kv1.2 tetramer reveal van der Waals coupling between hERG1 618- and 568-equivalent residues and a significant increase in interaction energies when threonine is introduced at the 618-equivalent position. We propose that coupling between the S5 segment and pore helix may participate in the inactivation process in hERG1 channels.
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Affiliation(s)
- Tania Ferrer
- From the Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah 84112
| | | | - Marcelo Arias
- From the Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah 84112
| | - Eckhard Ficker
- the Rammelkamp Center for Education and Research, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio 44109
| | - David Medovoy
- the Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, and
| | - Eduardo Perozo
- the Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, and
| | - Martin Tristani-Firouzi
- From the Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah 84112
- the Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah 84113
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Cordero-Morales JF, Jogini V, Chakrapani S, Perozo E. A multipoint hydrogen-bond network underlying KcsA C-type inactivation. Biophys J 2011; 100:2387-93. [PMID: 21575572 DOI: 10.1016/j.bpj.2011.01.073] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 01/19/2011] [Accepted: 01/31/2011] [Indexed: 10/18/2022] Open
Abstract
In the prokaryotic potassium channel KcsA activation gating at the inner bundle gate is followed by C-type inactivation at the selectivity filter. Entry into the C-type inactivated state has been directly linked to the strength of the H-bond interaction between residues Glu-71 and Asp-80 behind the filter, and is allosterically triggered by the rearrangement of the inner bundle gate. Here, we show that H-bond pairing between residues Trp-67 and Asp-80, conserved in most K⁺ channels, constitutes another critical interaction that determines the rate and extent of KcsA C-type inactivation. Disruption of the equivalent interaction in Shaker (Trp-434-Asp-447) and Kv1.2 (Trp-366-Asp-379) leads also to modulation of the inactivation process, suggesting that these residues also play an analogous role in the inactivation gating of Kv channels. The present results show that in KcsA C-type inactivation gating is governed by a multipoint hydrogen-bond network formed by the triad Trp-67-Glu71-Asp-80. This triad exerts a critical role in the dynamics and conformational stability of the selectivity filter and might serve as a general modulator of selectivity filter gating in other members of the K⁺ channel family.
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Affiliation(s)
- Julio F Cordero-Morales
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois, USA
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Gracheva EO, Cordero-Morales JF, González-Carcacía JA, Ingolia NT, Manno C, Aranguren CI, Weissman JS, Julius D. Ganglion-specific splicing of TRPV1 underlies infrared sensation in vampire bats. Nature 2011; 476:88-91. [PMID: 21814281 PMCID: PMC3535012 DOI: 10.1038/nature10245] [Citation(s) in RCA: 151] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Accepted: 06/03/2011] [Indexed: 01/06/2023]
Abstract
Vampire bats (Desmodus rotundus) are obligate blood feeders that have evolved specialized systems to suit their unique sanguinary lifestyle 1–3. Chief among such adaptations is the ability to detect infrared radiation as a means of locating hot spots on warm-blooded prey. Among vertebrates, only vampire bats, boas, pythons, and pit vipers are capable of detecting infrared radiation 1,4. In each case, infrared heat is detected by trigeminal nerve fibers that innervate specialized pit organs on the animal’s face 5–10. Thus, vampire bats and snakes have taken thermosensation to the extreme by developing specialized systems for detecting infrared radiation. As such, these creatures provide a window into the molecular and genetic mechanisms underlying evolutionary tuning of thermoreceptors in a species or cell type specific manner. Previously, we have shown that snakes co-opt a non-heat sensitive channel (vertebrate TRPA1) to produce an infrared detector 6. Here we show that vampire bats tune an already heat sensitive channel (TRPV1) by lowering its thermal activation threshold to ~30°C. This is achieved through alternative splicing of TRPV1 transcripts to produce a channel with a truncated C-terminal cytoplasmic domain. Remarkably, these splicing events occur exclusively in trigeminal ganglia (TG), and not dorsal root ganglia (DRG), thereby maintaining a role for TRPV1 as a detector of noxious heat in somatic afferents. This reflects a unique organization of the bat TRPV1 gene that we show to be characteristic of Laurasiatheria mammals (cows, dogs, and moles), supporting a close phylogenetic relationship with bats. These findings reveal a unique molecular mechanism for physiological tuning of thermosensory nerve fibers.
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Affiliation(s)
- Elena O Gracheva
- Department of Physiology, University of California, San Francisco, California 94158-2517, USA
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Cordero-Morales JF, Jogini V, Lewis A, Vasquez V, Medovoy D, Tristani-Firouzi M, Perozo E. Structural Basis of an Inherited hERG1 Long QT Mutant. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.2517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Cuello LG, Jogini V, Cortes DM, Pan AC, Gagnon DG, Dalmas O, Cordero-Morales JF, Chakrapani S, Roux B, Perozo E. Structural basis for the coupling between activation and inactivation gates in K(+) channels. Nature 2010; 466:272-5. [PMID: 20613845 DOI: 10.1038/nature09136] [Citation(s) in RCA: 230] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Accepted: 04/30/2010] [Indexed: 12/18/2022]
Abstract
The coupled interplay between activation and inactivation gating is a functional hallmark of K(+) channels. This coupling has been experimentally demonstrated through ion interaction effects and cysteine accessibility, and is associated with a well defined boundary of energetically coupled residues. The structure of the K(+) channel KcsA in its fully open conformation, in addition to four other partial channel openings, richly illustrates the structural basis of activation-inactivation gating. Here, we identify the mechanistic principles by which movements on the inner bundle gate trigger conformational changes at the selectivity filter, leading to the non-conductive C-type inactivated state. Analysis of a series of KcsA open structures suggests that, as a consequence of the hinge-bending and rotation of the TM2 helix, the aromatic ring of Phe 103 tilts towards residues Thr 74 and Thr 75 in the pore-helix and towards Ile 100 in the neighbouring subunit. This allows the network of hydrogen bonds among residues Trp 67, Glu 71 and Asp 80 to destabilize the selectivity filter, allowing entry to its non-conductive conformation. Mutations at position 103 have a size-dependent effect on gating kinetics: small side-chain substitutions F103A and F103C severely impair inactivation kinetics, whereas larger side chains such as F103W have more subtle effects. This suggests that the allosteric coupling between the inner helical bundle and the selectivity filter might rely on straightforward mechanical deformation propagated through a network of steric contacts. Average interactions calculated from molecular dynamics simulations show favourable open-state interaction-energies between Phe 103 and the surrounding residues. We probed similar interactions in the Shaker K(+) channel where inactivation was impaired in the mutant I470A. We propose that side-chain rearrangements at position 103 mechanically couple activation and inactivation in KcsA and a variety of other K(+) channels.
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Affiliation(s)
- Luis G Cuello
- Department of Biochemistry and Molecular Biology, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, USA
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Cordero-Morales JF, Jogini V, Lewis A, Vasquez V, Tristani-Firouzi M, Perozo E. On the Nature of hERG Inactivation using KcsA, Shaker and Kv1.2 as Structural and Functional Models. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Abstract
The prokaryotic K+ channel KcsA is activated by intracellular protons and its gating is modulated by transmembrane voltage. Typically, KcsA functions have been studied under steady-state conditions, using macroscopic Rb+-flux experiments and single-channel current measurements. These studies have provided limited insights into the gating kinetics of KcsA due to its low open probability, uncertainties in the number of channels in the patch, and a very strong intrinsic kinetic variability. In this work, we have carried out a detailed analysis of KcsA gating under nonstationary conditions by examining the influence of pH and voltage on the activation, deactivation, and slow-inactivation gating events. We find that activation and deactivation gating of KcsA are predominantly modulated by pH without a significant effect of voltage. Activation gating showed sigmoidal pH dependence with a pKa of ∼4.2 and a Hill coefficient of ∼2. In the sustained presence of proton, KcsA undergoes a time-dependent decay of conductance. This inactivation process is pH independent but is modulated by voltage and the nature of permeant ion. Recovery from inactivation occurs via deactivation and also appears to be voltage dependent. We further find that inactivation in KcsA is not entirely a property of the open-conducting channel but can also occur from partially “activated” closed states. The time course of onset and recovery of the inactivation process from these pre-open closed states appears to be different from the open-state inactivation, suggesting the presence of multiple inactivated states with diverse kinetic pathways. This information has been analyzed together with a detailed study of KcsA single-channel behavior (in the accompanying paper) in the framework of a kinetic model. Taken together our data constitutes the first quantitative description of KcsA gating.
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Affiliation(s)
- Sudha Chakrapani
- Institute of Molecular Pediatrics Science, Department of Biochemistry and Molecular Biology, University of Chicago, Center for integrative Science, Chicago, IL 60637, USA
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Abstract
The kinetic transitions of proton-activated WT KcsA and the noninactivating E71A mutant were studied at the single-channel level in purified, liposome-reconstituted preparations. Single-channel currents were recorded using patch-clamp techniques under nonstationary and steady-state conditions. Maximum-likelihood analyses reveal that the key influence of acidic pH is to increase the frequency of bursting without an effect on the intraburst open and closed dwell times, consistent with the finding from macroscopic currents that protons promote activation without a significant effect on inactivation. However, in steady-conditions of pH, voltage not only alters the burst frequency but also affects their properties, such as the frequency of the flickers and the dwell times of the closed and open states. This is to be expected if voltage modulates pathways connecting open and inactivated states. Upon opening, KcsA can enter at least two closed states that are not part of the activation pathway. The frequency and duration of these closed states was found to be voltage dependent and therefore these are likely to represent short-lived inactivated states. Single-channel recordings of WT KcsA also show varying propensity for the presence of subconductance states. The probability of occurrence of these states did not show clear modulation by voltage or pH and their origin remains unclear and a focus for further investigation. A kinetic model is proposed to describe the gating events in KcsA that recapitulates its macroscopic and single-channel behavior. The model has been constrained by the single-channel analyses presented in this work along with data from macroscopic currents in the preceding paper.
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Affiliation(s)
- Sudha Chakrapani
- Institute of Molecular Pediatrics Science, Department of Biochemistry and Molecular Biology, University of Chicago, Center for Integrative Science, Chicago, IL 60637, USA
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Cordero-Morales JF, Jogini V, Lewis A, Vásquez V, Cortes DM, Roux B, Perozo E. Molecular driving forces determining potassium channel slow inactivation. Nat Struct Mol Biol 2007; 14:1062-9. [PMID: 17922012 DOI: 10.1038/nsmb1309] [Citation(s) in RCA: 197] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Accepted: 09/04/2007] [Indexed: 11/09/2022]
Abstract
K+ channels undergo a time-dependent slow inactivation process that plays a key role in modulating cellular excitability. Here we show that in the prokaryotic proton-gated K+ channel KcsA, the number and strength of hydrogen bonds between residues in the selectivity filter and its adjacent pore helix determine the rate and extent of C-type inactivation. Upon channel activation, the interaction between residues at positions Glu71 and Asp80 promotes filter constriction parallel to the permeation pathway, which affects K+-binding sites and presumably abrogates ion conduction. Coupling between these two positions results in a quantitative correlation between their interaction strength and the stability of the inactivated state. Engineering of these interactions in the eukaryotic voltage-dependent K+ channel Kv1.2 suggests that a similar mechanistic principle applies to other K+ channels. These observations provide a plausible physical framework for understanding C-type inactivation in K+ channels.
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Affiliation(s)
- Julio F Cordero-Morales
- Department of Molecular Physiology and Biological Physics, University of Virginia, 1300 JPA, Charlottesville, Virginia 22908, USA
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Blunck R, Cordero-Morales JF, Cuello LG, Perozo E, Bezanilla F. Detection of the opening of the bundle crossing in KcsA with fluorescence lifetime spectroscopy reveals the existence of two gates for ion conduction. ACTA ACUST UNITED AC 2006; 128:569-81. [PMID: 17043150 PMCID: PMC2151582 DOI: 10.1085/jgp.200609638] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The closed KcsA channel structure revealed a crossing of the cytosolic ends of the transmembrane helices blocking the permeation pathway. It is generally agreed that during channel opening this helical bundle crossing has to widen in order to enable access to the inner cavity. Here, we address the question of whether the opening of the inner gate is sufficient for ion conduction, or if a second gate, located elsewhere, may interrupt the ion flow. We used fluorescence lifetime measurements on KcsA channels labeled with tetramethylrhodamine at residues in the C-terminal end of TM2 to report on the opening of the lower pore region. We found two populations of channels with different fluorescence lifetimes, whose relative distribution agrees with the open probability of the channel. The absolute fraction of channels found with an open bundle crossing is too high to explain the low open probability of the KcsA-WT channel. We found the same distribution as in the WT channel between open and closed bundle crossing for two KcsA mutants, A73E and E71A, which significantly increase open probability at low pH. These two results strongly suggest that a second gate in the ion permeation pathway exists. The location of the mutations A73E and E71A suggests that the second gate may be the selectivity filter, which resides in an inactivated state under steady-state conditions. Since the long closed times observed in KcsA-WT are not present in KcsA-A73E or -E71A, we propose that KcsA-WT remains predominantly in a state with an open bundle crossing but closed (inactivated) second gate, while the mutations A73E and E71A sharply decrease the tendency to enter in the inactivated state, and as a consequence, the second gate is predominantly open at steady state. The ability to monitor the opening of the bundle crossing optically enables the direct recording of the movement of the pore helices while the channel is functioning.
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Affiliation(s)
- Rikard Blunck
- Département de Physique et Groupe d'Etude des Protéines Membranaires (GEPROM), Université de Montréal, Montréal, Québec, H3C 3J7, Canada.
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Cordero-Morales JF, Cuello LG, Zhao Y, Jogini V, Cortes DM, Roux B, Perozo E. Molecular determinants of gating at the potassium-channel selectivity filter. Nat Struct Mol Biol 2006; 13:311-8. [PMID: 16532009 DOI: 10.1038/nsmb1069] [Citation(s) in RCA: 350] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Accepted: 01/18/2006] [Indexed: 11/09/2022]
Abstract
We show that in the potassium channel KcsA, proton-dependent activation is followed by an inactivation process similar to C-type inactivation, and this process is suppressed by an E71A mutation in the pore helix. EPR spectroscopy demonstrates that the inner gate opens maximally at low pH regardless of the magnitude of the single-channel-open probability, implying that stationary gating originates mostly from rearrangements at the selectivity filter. Two E71A crystal structures obtained at 2.5 A reveal large structural excursions of the selectivity filter during ion conduction and provide a glimpse of the range of conformations available to this region of the channel during gating. These data establish a mechanistic basis for the role of the selectivity filter during channel activation and inactivation.
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Affiliation(s)
- Julio F Cordero-Morales
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22906, USA
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Cordero-Morales JF, Cuello LG, Perozo E. Voltage-dependent gating at the KcsA selectivity filter. Nat Struct Mol Biol 2006; 13:319-22. [PMID: 16532008 DOI: 10.1038/nsmb1070] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Accepted: 01/18/2006] [Indexed: 11/08/2022]
Abstract
The prokaryotic K(+) channel KcsA, although lacking a 'standard' voltage-sensing domain, shows voltage-dependent gating that leads to an increase in steady-state open probability of almost two orders of magnitude between +150 and -150 mV. Here we show that voltage-dependent gating in KcsA is associated with the movement of approximately 0.7 equivalent electronic charges. This charge movement produces an increase in the rate of entry into a long-lived inactivated state and seems to be independent of the proton-activation mechanism. Charge neutralization at position 71 renders the channel essentially voltage-independent by preventing entry into the inactivated state. A mechanism for voltage-dependent gating at the selectivity filter is proposed that is based on the reorientation of the carboxylic moiety of Glu71 and its influence in the conformational dynamics of the selectivity filter.
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Affiliation(s)
- Julio F Cordero-Morales
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22906, USA
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