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Patton BL, Zhu P, ElSheikh A, Driggers CM, Shyng SL. Dynamic duo: Kir6 and SUR in K ATP channel structure and function. Channels (Austin) 2024; 18:2327708. [PMID: 38489043 PMCID: PMC10950283 DOI: 10.1080/19336950.2024.2327708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 01/14/2024] [Indexed: 03/17/2024] Open
Abstract
KATP channels are ligand-gated potassium channels that couple cellular energetics with membrane potential to regulate cell activity. Each channel is an eight subunit complex comprising four central pore-forming Kir6 inward rectifier potassium channel subunits surrounded by four regulatory subunits known as the sulfonylurea receptor, SUR, which confer homeostatic metabolic control of KATP gating. SUR is an ATP binding cassette (ABC) protein family homolog that lacks membrane transport activity but is essential for KATP expression and function. For more than four decades, understanding the structure-function relationship of Kir6 and SUR has remained a central objective of clinical significance. Here, we review progress in correlating the wealth of functional data in the literature with recent KATP cryoEM structures.
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Affiliation(s)
- Bruce L. Patton
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, OR, USA
| | - Phillip Zhu
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, OR, USA
| | - Assmaa ElSheikh
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, OR, USA
- Department of Medical Biochemistry, Tanta University, Tanta, Egypt
| | - Camden M. Driggers
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, OR, USA
| | - Show-Ling Shyng
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, OR, USA
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2
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Prawitt D, Eggermann T. Molecular mechanisms of human overgrowth and use of omics in its diagnostics: chances and challenges. Front Genet 2024; 15:1382371. [PMID: 38894719 PMCID: PMC11183334 DOI: 10.3389/fgene.2024.1382371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 05/14/2024] [Indexed: 06/21/2024] Open
Abstract
Overgrowth disorders comprise a group of entities with a variable phenotypic spectrum ranging from tall stature to isolated or lateralized overgrowth of body parts and or organs. Depending on the underlying physiological pathway affected by pathogenic genetic alterations, overgrowth syndromes are associated with a broad spectrum of neoplasia predisposition, (cardio) vascular and neurodevelopmental anomalies, and dysmorphisms. Pathologic overgrowth may be of prenatal or postnatal onset. It either results from an increased number of cells (intrinsic cellular hyperplasia), hypertrophy of the normal number of cells, an increase in interstitial spaces, or from a combination of all of these. The underlying molecular causes comprise a growing number of genetic alterations affecting skeletal growth and Growth-relevant signaling cascades as major effectors, and they can affect the whole body or parts of it (mosaicism). Furthermore, epigenetic modifications play a critical role in the manifestation of some overgrowth diseases. The diagnosis of overgrowth syndromes as the prerequisite of a personalized clinical management can be challenging, due to their clinical and molecular heterogeneity. Physicians should consider molecular genetic testing as a first diagnostic step in overgrowth syndromes. In particular, the urgent need for a precise diagnosis in tumor predisposition syndromes has to be taken into account as the basis for an early monitoring and therapy. With the (future) implementation of next-generation sequencing approaches and further omic technologies, clinical diagnoses can not only be verified, but they also confirm the clinical and molecular spectrum of overgrowth disorders, including unexpected findings and identification of atypical cases. However, the limitations of the applied assays have to be considered, for each of the disorders of interest, the spectrum of possible types of genomic variants has to be considered as they might require different methodological strategies. Additionally, the integration of artificial intelligence (AI) in diagnostic workflows significantly contribute to the phenotype-driven selection and interpretation of molecular and physiological data.
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Affiliation(s)
- Dirk Prawitt
- Center for Pediatrics and Adolescent Medicine, University Medical Center, Mainz, Germany
| | - Thomas Eggermann
- Institute for Human Genetics and Genome Medicine, Medical Faculty, RWTH Aachen, Aachen, Germany
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3
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Efthymiou S, Scala M, Nagaraj V, Ochenkowska K, Komdeur FL, Liang RA, Abdel-Hamid MS, Sultan T, Barøy T, Van Ghelue M, Vona B, Maroofian R, Zafar F, Alkuraya FS, Zaki MS, Severino M, Duru KC, Tryon RC, Brauteset LV, Ansari M, Hamilton M, van Haelst MM, van Haaften G, Zara F, Houlden H, Samarut É, Nichols CG, Smeland MF, McClenaghan C. Novel loss-of-function variants expand ABCC9-related intellectual disability and myopathy syndrome. Brain 2024; 147:1822-1836. [PMID: 38217872 PMCID: PMC11068106 DOI: 10.1093/brain/awae010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 11/22/2023] [Accepted: 12/30/2023] [Indexed: 01/15/2024] Open
Abstract
Loss-of-function mutation of ABCC9, the gene encoding the SUR2 subunit of ATP sensitive-potassium (KATP) channels, was recently associated with autosomal recessive ABCC9-related intellectual disability and myopathy syndrome (AIMS). Here we identify nine additional subjects, from seven unrelated families, harbouring different homozygous loss-of-function variants in ABCC9 and presenting with a conserved range of clinical features. All variants are predicted to result in severe truncations or in-frame deletions within SUR2, leading to the generation of non-functional SUR2-dependent KATP channels. Affected individuals show psychomotor delay and intellectual disability of variable severity, microcephaly, corpus callosum and white matter abnormalities, seizures, spasticity, short stature, muscle fatigability and weakness. Heterozygous parents do not show any conserved clinical pathology but report multiple incidences of intra-uterine fetal death, which were also observed in an eighth family included in this study. In vivo studies of abcc9 loss-of-function in zebrafish revealed an exacerbated motor response to pentylenetetrazole, a pro-convulsive drug, consistent with impaired neurodevelopment associated with an increased seizure susceptibility. Our findings define an ABCC9 loss-of-function-related phenotype, expanding the genotypic and phenotypic spectrum of AIMS and reveal novel human pathologies arising from KATP channel dysfunction.
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Affiliation(s)
- Stephanie Efthymiou
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Marcello Scala
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16147 Genoa, Italy
- U.O.C. Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Vini Nagaraj
- Center for Advanced Biotechnology and Medicine, and Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers the State University of New Jersey, Piscatway, NJ 08854, USA
| | - Katarzyna Ochenkowska
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), and Department of Neuroscience, Université de Montréal, Montreal H2X 0A9, Quebec, Canada
| | - Fenne L Komdeur
- Section Clinical Genetics, Department of Human Genetics and Amsterdam Reproduction and Development, Amsterdam University Medical Centers, 1105 AZ, Amsterdam, The Netherlands
| | - Robin A Liang
- Department of Medical Genetics, Division of Child and Adolescent Health, University Hospital of North Norway, 9019 Tromsø, Norway
| | - Mohamed S Abdel-Hamid
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo 12622, Egypt
| | - Tipu Sultan
- Department of Pediatric Neurology, Children Hospital, University of Child Health Sciences, Lahore, Punjab 54000, Pakistan
| | - Tuva Barøy
- Department of Medical Genetics, Oslo University Hospital, 0450 Oslo, Norway
| | - Marijke Van Ghelue
- Department of Medical Genetics, Division of Child and Adolescent Health, University Hospital of North Norway, 9019 Tromsø, Norway
| | - Barbara Vona
- Institute of Human Genetics and Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Reza Maroofian
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Faisal Zafar
- Department of Paediatric Neurology, Children’s Hospital and Institute of Child Health, Multan, Punjab 60000, Pakistan
| | - Fowzan S Alkuraya
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh 12713, Saudi Arabia
| | - Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo 12622, Egypt
| | | | - Kingsley C Duru
- Center for Advanced Biotechnology and Medicine, and Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers the State University of New Jersey, Piscatway, NJ 08854, USA
| | - Robert C Tryon
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO 63110, USA
| | - Lin Vigdis Brauteset
- Division of Habilitation for Children, Innlandet Hospital Sanderud, Hamar 2312, Norway
| | - Morad Ansari
- South East Scotland Genetic Service, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Mark Hamilton
- West of Scotland Clinical Genetics Service, Queen Elizabeth University Hospital, Glasgow G51 4TF, UK
| | - Mieke M van Haelst
- Section Clinical Genetics, Department of Human Genetics and Amsterdam Reproduction and Development, Amsterdam University Medical Centers, 1105 AZ, Amsterdam, The Netherlands
| | - Gijs van Haaften
- Department of Genetics, University Medical Center, Utrecht, 3584 CX, The Netherlands
| | - Federico Zara
- U.O.C. Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Henry Houlden
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Éric Samarut
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), and Department of Neuroscience, Université de Montréal, Montreal H2X 0A9, Quebec, Canada
| | - Colin G Nichols
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO 63110, USA
| | - Marie F Smeland
- Department of Pediatric Rehabilitation, University Hospital of North Norway, 9019 Tromsø, Norway
- Institute of Clinical Medicine, UiT The Arctic University of Norway, 9019, Tromsø, Norway
| | - Conor McClenaghan
- Center for Advanced Biotechnology and Medicine, and Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers the State University of New Jersey, Piscatway, NJ 08854, USA
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4
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Yin B, Yu X, Fu X, Liu X, Xiao J, Yu L, Nie Y, Zhang Y. Expression and influence of KATP in umbilical artery smooth muscle cells of patients with hypertensive disorders of pregnancy. Sci Rep 2024; 14:7517. [PMID: 38553483 PMCID: PMC10980746 DOI: 10.1038/s41598-024-57885-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 03/22/2024] [Indexed: 04/02/2024] Open
Abstract
The objective of this study is to investigate the expression and influence of adenosine triphosphate-sensitive potassium channel (KATP) in human umbilical arterial smooth muscle cells (HUASMCs) of patients with hypertensive disorders of pregnancy (HDP). Western blotting was used to detect the protein expression levels of KATP inwardly rectifying potassium channel (Kir)6.1 and sulphonylurea receptor (SUR)2B subunits in HUASMCs from patients with normal parturients (NP), gestational hypertension (GH), chronic hypertension (CH), preeclampsia (PE) and chronic hypertension with superimposed preeclampsia (CHSP), respectively. There was no significant difference in the protein expression of Kir6.1 subunit in NP group, GH group, CH group, PE group and CHSP group (P > 0.05). The protein expression of SUR2B subunit was gradually decreased in NP group, GH group, CH group, PE group and CHSP group, with statistically significant difference among the groups (P < 0.05). The altered expression level of KATP SUR2B subunit may be involved in the pathogenesis of HDP. The severity of HDP may be related to the degree of decrease of SUR2B subunit.
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Affiliation(s)
- Benlan Yin
- Department of Obstetrics, The Affiliated Hospital of Southwest Medical University, No.8, Kangcheng Road, Luzhou, 646000, Sichuan, China
| | - Xiaotong Yu
- Department of Clinical Medicine, Southwest Medical University, No. 319, Section 3, Zhongshan Road, Luzhou, Sichuan, China
| | - Xiaodong Fu
- Department of Obstetrics, The Affiliated Hospital of Southwest Medical University, No.8, Kangcheng Road, Luzhou, 646000, Sichuan, China
| | - Xiyuan Liu
- Department of Clinical Medicine, Southwest Medical University, No. 319, Section 3, Zhongshan Road, Luzhou, Sichuan, China
| | - Jing Xiao
- Department of Clinical Medicine, Southwest Medical University, No. 319, Section 3, Zhongshan Road, Luzhou, Sichuan, China
| | - Linli Yu
- Department of Clinical Medicine, Southwest Medical University, No. 319, Section 3, Zhongshan Road, Luzhou, Sichuan, China
| | - Yunying Nie
- Department of Clinical Medicine, Southwest Medical University, No. 319, Section 3, Zhongshan Road, Luzhou, Sichuan, China
| | - Yujiao Zhang
- Department of Obstetrics, The Affiliated Hospital of Southwest Medical University, No.8, Kangcheng Road, Luzhou, 646000, Sichuan, China.
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Li K, McClenahan SJ, Han C, Bungard JD, Rathnayake U, Boutaud O, Bauer JA, Days EL, Lindsley CW, Shelton EL, Denton JS. Discovery and Characterization of VU0542270, the First Selective Inhibitor of Vascular Kir6.1/SUR2B K ATP Channels. Mol Pharmacol 2024; 105:202-212. [PMID: 38302135 PMCID: PMC10877733 DOI: 10.1124/molpharm.123.000783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 12/21/2023] [Accepted: 01/02/2024] [Indexed: 02/03/2024] Open
Abstract
Vascular smooth muscle KATP channels critically regulate blood flow and blood pressure by modulating vascular tone and therefore represent attractive drug targets for treating several cardiovascular disorders. However, the lack of potent inhibitors that can selectively inhibit Kir6.1/SUR2B (vascular KATP) over Kir6.2/SUR1 (pancreatic KATP) has eluded discovery despite decades of intensive research. We therefore screened 47,872 chemically diverse compounds for novel inhibitors of heterologously expressed Kir6.1/SUR2B channels. The most potent inhibitor identified in the screen was an N-aryl-N'-benzyl urea compound termed VU0542270. VU0542270 inhibits Kir6.1/SUR2B with an IC50 of approximately 100 nM but has no apparent activity toward Kir6.2/SUR1 or several other members of the Kir channel family at doses up to 30 µM (>300-fold selectivity). By expressing different combinations of Kir6.1 or Kir6.2 with SUR1, SUR2A, or SUR2B, the VU0542270 binding site was localized to SUR2. Initial structure-activity relationship exploration around VU0542270 revealed basic texture related to structural elements that are required for Kir6.1/SUR2B inhibition. Analysis of the pharmacokinetic properties of VU0542270 showed that it has a short in vivo half-life due to extensive metabolism. In pressure myography experiments on isolated mouse ductus arteriosus vessels, VU0542270 induced ductus arteriosus constriction in a dose-dependent manner similar to that of the nonspecific KATP channel inhibitor glibenclamide. The discovery of VU0542270 provides conceptual proof that SUR2-specific KATP channel inhibitors can be developed using a molecular target-based approach and offers hope for developing cardiovascular therapeutics targeting Kir6.1/SUR2B. SIGNIFICANCE STATEMENT: Small-molecule inhibitors of vascular smooth muscle KATP channels might represent novel therapeutics for patent ductus arteriosus, migraine headache, and sepsis; however, the lack of selective channel inhibitors has slowed progress in these therapeutic areas. Here, this study describes the discovery and characterization of the first vascular-specific KATP channel inhibitor, VU0542270.
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Affiliation(s)
- Kangjun Li
- Departments of Anesthesiology (K.L., S.J.M., J.S.D.), Pharmacology (K.L., C.H., J.D.B., U.R., O.B., C.W.L., J.S.D.), Pediatrics (E.L.S.), and Biochemistry (J.A.B.), Vanderbilt University Medical Center, Nashville, Tennessee and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (J.A.B., E.L.D., J.S.D.)
| | - Samantha J McClenahan
- Departments of Anesthesiology (K.L., S.J.M., J.S.D.), Pharmacology (K.L., C.H., J.D.B., U.R., O.B., C.W.L., J.S.D.), Pediatrics (E.L.S.), and Biochemistry (J.A.B.), Vanderbilt University Medical Center, Nashville, Tennessee and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (J.A.B., E.L.D., J.S.D.)
| | - Changho Han
- Departments of Anesthesiology (K.L., S.J.M., J.S.D.), Pharmacology (K.L., C.H., J.D.B., U.R., O.B., C.W.L., J.S.D.), Pediatrics (E.L.S.), and Biochemistry (J.A.B.), Vanderbilt University Medical Center, Nashville, Tennessee and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (J.A.B., E.L.D., J.S.D.)
| | - Joseph D Bungard
- Departments of Anesthesiology (K.L., S.J.M., J.S.D.), Pharmacology (K.L., C.H., J.D.B., U.R., O.B., C.W.L., J.S.D.), Pediatrics (E.L.S.), and Biochemistry (J.A.B.), Vanderbilt University Medical Center, Nashville, Tennessee and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (J.A.B., E.L.D., J.S.D.)
| | - Upendra Rathnayake
- Departments of Anesthesiology (K.L., S.J.M., J.S.D.), Pharmacology (K.L., C.H., J.D.B., U.R., O.B., C.W.L., J.S.D.), Pediatrics (E.L.S.), and Biochemistry (J.A.B.), Vanderbilt University Medical Center, Nashville, Tennessee and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (J.A.B., E.L.D., J.S.D.)
| | - Olivier Boutaud
- Departments of Anesthesiology (K.L., S.J.M., J.S.D.), Pharmacology (K.L., C.H., J.D.B., U.R., O.B., C.W.L., J.S.D.), Pediatrics (E.L.S.), and Biochemistry (J.A.B.), Vanderbilt University Medical Center, Nashville, Tennessee and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (J.A.B., E.L.D., J.S.D.)
| | - Joshua A Bauer
- Departments of Anesthesiology (K.L., S.J.M., J.S.D.), Pharmacology (K.L., C.H., J.D.B., U.R., O.B., C.W.L., J.S.D.), Pediatrics (E.L.S.), and Biochemistry (J.A.B.), Vanderbilt University Medical Center, Nashville, Tennessee and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (J.A.B., E.L.D., J.S.D.)
| | - Emily L Days
- Departments of Anesthesiology (K.L., S.J.M., J.S.D.), Pharmacology (K.L., C.H., J.D.B., U.R., O.B., C.W.L., J.S.D.), Pediatrics (E.L.S.), and Biochemistry (J.A.B.), Vanderbilt University Medical Center, Nashville, Tennessee and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (J.A.B., E.L.D., J.S.D.)
| | - Craig W Lindsley
- Departments of Anesthesiology (K.L., S.J.M., J.S.D.), Pharmacology (K.L., C.H., J.D.B., U.R., O.B., C.W.L., J.S.D.), Pediatrics (E.L.S.), and Biochemistry (J.A.B.), Vanderbilt University Medical Center, Nashville, Tennessee and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (J.A.B., E.L.D., J.S.D.)
| | - Elaine L Shelton
- Departments of Anesthesiology (K.L., S.J.M., J.S.D.), Pharmacology (K.L., C.H., J.D.B., U.R., O.B., C.W.L., J.S.D.), Pediatrics (E.L.S.), and Biochemistry (J.A.B.), Vanderbilt University Medical Center, Nashville, Tennessee and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (J.A.B., E.L.D., J.S.D.)
| | - Jerod S Denton
- Departments of Anesthesiology (K.L., S.J.M., J.S.D.), Pharmacology (K.L., C.H., J.D.B., U.R., O.B., C.W.L., J.S.D.), Pediatrics (E.L.S.), and Biochemistry (J.A.B.), Vanderbilt University Medical Center, Nashville, Tennessee and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (J.A.B., E.L.D., J.S.D.)
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Gando I, Becerra Flores M, Chen IS, Yang HQ, Nakamura TY, Cardozo TJ, Coetzee WA. CL-705G: a novel chemical Kir6.2-specific K ATP channel opener. Front Pharmacol 2023; 14:1197257. [PMID: 37408765 PMCID: PMC10319115 DOI: 10.3389/fphar.2023.1197257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 06/01/2023] [Indexed: 07/07/2023] Open
Abstract
Background: KATP channels have diverse roles, including regulation of insulin secretion and blood flow, and protection against biological stress responses and are excellent therapeutic targets. Different subclasses of KATP channels exist in various tissue types due to the unique assemblies of specific pore-forming (Kir6.x) and accessory (SURx) subunits. The majority of pharmacological openers and blockers act by binding to SURx and are poorly selective against the various KATP channel subclasses. Methods and Results: We used 3D models of the Kir6.2/SUR homotetramers based on existing cryo-EM structures of channels in both the open and closed states to identify a potential agonist binding pocket in a functionally critical area of the channel. Computational docking screens of this pocket with the Chembridge Core chemical library of 492,000 drug-like compounds yielded 15 top-ranked "hits", which were tested for activity against KATP channels using patch clamping and thallium (Tl+) flux assays with a Kir6.2/SUR2A HEK-293 stable cell line. Several of the compounds increased Tl+ fluxes. One of them (CL-705G) opened Kir6.2/SUR2A channels with a similar potency as pinacidil (EC50 of 9 µM and 11 μM, respectively). Remarkably, compound CL-705G had no or minimal effects on other Kir channels, including Kir6.1/SUR2B, Kir2.1, or Kir3.1/Kir3.4 channels, or Na+ currents of TE671 medulloblastoma cells. CL-705G activated Kir6.2Δ36 in the presence of SUR2A, but not when expressed by itself. CL-705G activated Kir6.2/SUR2A channels even after PIP2 depletion. The compound has cardioprotective effects in a cellular model of pharmacological preconditioning. It also partially rescued activity of the gating-defective Kir6.2-R301C mutant that is associated with congenital hyperinsulinism. Conclusion: CL-705G is a new Kir6.2 opener with little cross-reactivity with other channels tested, including the structurally similar Kir6.1. This, to our knowledge, is the first Kir-specific channel opener.
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Affiliation(s)
- Ivan Gando
- Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, United States
| | - Manuel Becerra Flores
- Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, United States
| | - I.-Shan Chen
- Phamacology, Wakayama Medical University, Wakayama, Japan
| | - Hua-Qian Yang
- Cyrus Tang Hematology Center, Soochow University, Suzhou, China
| | | | - Timothy J. Cardozo
- Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, United States
| | - William A. Coetzee
- Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, United States
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7
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Martin GM, Patton BL, Shyng SL. K ATP channels in focus: Progress toward a structural understanding of ligand regulation. Curr Opin Struct Biol 2023; 79:102541. [PMID: 36807078 PMCID: PMC10023423 DOI: 10.1016/j.sbi.2023.102541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 12/11/2022] [Accepted: 01/14/2023] [Indexed: 02/21/2023]
Abstract
KATP channels are hetero-octameric complexes of four inward rectifying potassium channels, Kir6.1 or Kir6.2, and four sulfonylurea receptors, SUR1, SUR2A, or SUR2B from the ABC transporter family. This unique combination enables KATP channels to couple intracellular ATP/ADP ratios, through gating, with membrane excitability, thus regulating a broad range of cellular activities. The prominence of KATP channels in human physiology, disease, and pharmacology has long attracted research interest. Since 2017, a steady flow of high-resolution KATP cryoEM structures has revealed complex and dynamic interactions between channel subunits and their ligands. Here, we highlight insights from recent structures that begin to provide mechanistic explanations for decades of experimental data and discuss the remaining knowledge gaps in our understanding of KATP channel regulation.
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Affiliation(s)
- Gregory M Martin
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Bruce L Patton
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Show-Ling Shyng
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, OR, 97239, USA.
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8
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Scala R, Maqoud F, McClenaghan C, Harter TM, Perrone MG, Scilimati A, Nichols CG, Tricarico D. Zoledronic Acid Blocks Overactive Kir6.1/SUR2-Dependent K ATP Channels in Skeletal Muscle and Osteoblasts in a Murine Model of Cantú Syndrome. Cells 2023; 12:928. [PMID: 36980269 PMCID: PMC10047381 DOI: 10.3390/cells12060928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/24/2023] [Accepted: 03/11/2023] [Indexed: 03/22/2023] Open
Abstract
Cantú syndrome (CS) is caused by the gain of function mutations in the ABCC9 and KCNJ8 genes encoding, respectively, for the sulfonylureas receptor type 2 (SUR2) and the inwardly rectifier potassium channel 6.1 (Kir6.1) of the ATP-sensitive potassium (KATP) channels. CS is a multi-organ condition with a cardiovascular phenotype, neuromuscular symptoms, and skeletal malformations. Glibenclamide has been proposed for use in CS, but even in animals, the drug is incompletely effective against severe mutations, including the Kir6.1wt/V65M. Patch-clamp experiments showed that zoledronic acid (ZOL) fully reduced the whole-cell KATP currents in bone calvaria cells from wild type (WT/WT) and heterozygous Kir6.1wt/V65MCS mice, with IC50 for ZOL block < 1 nM in each case. ZOL fully reduced KATP current in excised patches in skeletal muscle fibers in WT/WT and CS mice, with IC50 of 100 nM in each case. Interestingly, KATP currents in the bone of heterozygous SUR2wt/A478V mice were less sensitive to ZOL inhibition, showing an IC50 of ~500 nM and a slope of ~0.3. In homozygous SUR2A478V/A478V cells, ZOL failed to fully inhibit the KATP currents, causing only ~35% inhibition at 100 μM, but was responsive to glibenclamide. ZOL reduced the KATP currents in Kir6.1wt/VMCS mice in both skeletal muscle and bone cells but was not effective in the SUR2[A478V] mice fibers. These data indicate a subunit specificity of ZOL action that is important for appropriate CS therapies.
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Affiliation(s)
- Rosa Scala
- Sections of Pharmacology, Medicinal Chemistry, Department of Pharmacy—Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy
| | - Fatima Maqoud
- Sections of Pharmacology, Medicinal Chemistry, Department of Pharmacy—Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy
| | - Conor McClenaghan
- Center for the Investigation of Membrane Excitability Diseases, Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110-1010, USA
| | - Theresa M. Harter
- Center for the Investigation of Membrane Excitability Diseases, Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110-1010, USA
| | - Maria Grazia Perrone
- Sections of Pharmacology, Medicinal Chemistry, Department of Pharmacy—Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy
| | - Antonio Scilimati
- Sections of Pharmacology, Medicinal Chemistry, Department of Pharmacy—Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy
| | - Colin G. Nichols
- Center for the Investigation of Membrane Excitability Diseases, Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110-1010, USA
| | - Domenico Tricarico
- Sections of Pharmacology, Medicinal Chemistry, Department of Pharmacy—Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy
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9
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Denton JS, Delpire E. Special collection on inward rectifying K + channels. Am J Physiol Cell Physiol 2023; 324:C603-C605. [PMID: 36689674 PMCID: PMC9942886 DOI: 10.1152/ajpcell.00457.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 01/13/2023] [Accepted: 01/13/2023] [Indexed: 01/25/2023]
Affiliation(s)
- Jerod S Denton
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
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10
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Driggers CM, Shyng SL. Mechanistic insights on KATP channel regulation from cryo-EM structures. J Gen Physiol 2022; 155:213723. [PMID: 36441147 PMCID: PMC9700523 DOI: 10.1085/jgp.202113046] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 10/19/2022] [Accepted: 11/08/2022] [Indexed: 11/29/2022] Open
Abstract
Gated by intracellular ATP and ADP, ATP-sensitive potassium (KATP) channels couple cell energetics with membrane excitability in many cell types, enabling them to control a wide range of physiological processes based on metabolic demands. The KATP channel is a complex of four potassium channel subunits from the Kir channel family, Kir6.1 or Kir6.2, and four sulfonylurea receptor subunits, SUR1, SUR2A, or SUR2B, from the ATP-binding cassette (ABC) transporter family. Dysfunction of KATP channels underlies several human diseases. The importance of these channels in human health and disease has made them attractive drug targets. How the channel subunits interact with one another and how the ligands interact with the channel to regulate channel activity have been long-standing questions in the field. In the past 5 yr, a steady stream of high-resolution KATP channel structures has been published using single-particle cryo-electron microscopy (cryo-EM). Here, we review the advances these structures bring to our understanding of channel regulation by physiological and pharmacological ligands.
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Affiliation(s)
- Camden M. Driggers
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, OR
| | - Show-Ling Shyng
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, OR,Correspondence to Show-Ling Shyng:
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11
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Crespo-García T, Rubio-Alarcón M, Cámara-Checa A, Dago M, Rapún J, Nieto-Marín P, Marín M, Cebrián J, Tamargo J, Delpón E, Caballero R. A Cantú syndrome mutation produces dual effects on KATP channels by disrupting ankyrin B regulation. J Gen Physiol 2022; 155:213613. [PMID: 36287534 PMCID: PMC9614705 DOI: 10.1085/jgp.202112995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/09/2022] [Accepted: 10/04/2022] [Indexed: 02/01/2023] Open
Abstract
ATP-sensitive potassium (KATP) channels composed of Kir6.x and sulfonylurea receptor (SURs) subunits couple cellular metabolism to electrical activity. Cantú syndrome (CS) is a rare disease caused by mutations in the genes encoding Kir6.1 (KCNJ8) and SUR2A (ABCC9) that produce KATP channel hyperactivity due to a reduced channel block by physiological ATP concentrations. We functionally characterized the p.S1054Y SUR2A mutation identified in two CS carriers, who exhibited a mild phenotype although the mutation was predicted as highly pathogenic. We recorded macroscopic and single-channel currents in CHO and HEK-293 cells and measured the membrane expression of the channel subunits by biotinylation assays in HEK-293 cells. The mutation increased basal whole-cell current density and at the single-channel level, it augmented opening frequency, slope conductance, and open probability (Po), and promoted the appearance of multiple conductance levels. p.S1054Y also reduced Kir6.2 and SUR2A expression specifically at the membrane. Overexpression of ankyrin B (AnkB) prevented these gain- and loss-of-function effects, as well as the p.S1054Y-induced reduction of ATP inhibition of currents measured in inside-out macropatches. Yeast two-hybrid assays suggested that SUR2A WT and AnkB interact, while p.S1054Y interaction with AnkB is decreased. The p.E322K Kir6.2 mutation, which prevents AnkB binding to Kir6.2, produced similar biophysical alterations than p.S1054Y. Our results are the first demonstration of a CS mutation whose functional consequences involve the disruption of AnkB effects on KATP channels providing a novel mechanism by which CS mutations can reduce ATP block. Furthermore, they may help explain the mild phenotype associated with this mutation.
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Affiliation(s)
- Teresa Crespo-García
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Marcos Rubio-Alarcón
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Anabel Cámara-Checa
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - María Dago
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Josu Rapún
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Paloma Nieto-Marín
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - María Marín
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Jorge Cebrián
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Juan Tamargo
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Eva Delpón
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain,Correspondence to Eva Delpón:
| | - Ricardo Caballero
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
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