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Fraile A, Cebrián J, Thuissard-Vasallo I, Pérez-Martín S, Casado R, Gil-Fournier B, Alonso-Martín J, Tamargo J, Caballero R, Delpón E, Cosío FG. Coexistent HCN4 and GATA5 rare variants and Atrial Fibrillation in a large Spanish Family. Can J Cardiol 2024:S0828-282X(24)00189-2. [PMID: 38432398 DOI: 10.1016/j.cjca.2024.02.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 02/02/2024] [Accepted: 02/28/2024] [Indexed: 03/05/2024] Open
Abstract
BACKGROUND Familial association of atrial fibrillation (AF) can involve single gene variants related to known arrhythmogenic mechanisms; however, genome-wide association studies often disclose complex genetic variants in familial and non-familial AF, making it difficult to relate to known pathogenetic mechanisms. METHODS The finding of 4 siblings with AF led to studying 47 members of a family. Long-term Holter monitoring (298 hours average) ruled out silent AFWhole-exome sequencing was performed and variants shared by the index cases were filtered and prioritized according to current recommendations. HCN4 currents (IHCN4) were recorded in Chinese hamster ovary cells expressing human p.P1163H and/or native Hcn4 channels using the patch-clamp technique and topologically associated domain analysis of GATA5 variant carriers were performed. RESULTS The clinical study diagnosed 2 more AF cases. Five family members carried the heterozygous p.P1163H, HCN4 variant, 14 the intronic 20,61040536,G,A GATA5 rare variant, and 9 carried both variants (HCN4+GATA5). Five of the 6 AF cases (onset age ranging 33-70 years) carried both variants and one the GATA5 variant alone. Multivariate analysis showed that the presence of HCN4+GATA5 variants significantly and independently increased AF risk [OR=32.740 (1.812-591.408)] and not age, hypertension or overweight. Functional testing showed that IHcn4 generated by heterozygous p.P1163H were normal. Topologically associating domain analysis suggested that GATA5 could affect the expression of many genes, including those encoding microRNA-1. CONCLUSION The coincidence of two rare gene variants was independently associated with AF, but functional studies do not allow the postulation of the arrhythmogenic mechanism(s) involved.
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Affiliation(s)
- Alfonso Fraile
- Cardiology Department. Hospital Universitario de Getafe. Carretera de Toledo, Km. 12,500. 28905-Getafe, Spain.
| | - Jorge Cebrián
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid. Instituto de Investigación Gregorio Marañón. CIBERCV. 28040-Madrid, Spain
| | - Israel Thuissard-Vasallo
- Department of Biomedical and Health Sciences. Universidad Europea de Madrid. 28670-Madrid, Spain
| | - Sara Pérez-Martín
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid. Instituto de Investigación Gregorio Marañón. CIBERCV. 28040-Madrid, Spain
| | - Raquel Casado
- Cardiology Department. Hospital Universitario de Getafe. Carretera de Toledo, Km. 12,500. 28905-Getafe, Spain
| | - Belen Gil-Fournier
- Cardiology Department. Hospital Universitario de Getafe. Carretera de Toledo, Km. 12,500. 28905-Getafe, Spain
| | - Joaquín Alonso-Martín
- Cardiology Department. Hospital Universitario de Getafe. Carretera de Toledo, Km. 12,500. 28905-Getafe, Spain
| | - Juan Tamargo
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid. Instituto de Investigación Gregorio Marañón. CIBERCV. 28040-Madrid, Spain
| | - Ricardo Caballero
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid. Instituto de Investigación Gregorio Marañón. CIBERCV. 28040-Madrid, Spain.
| | - Eva Delpón
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid. Instituto de Investigación Gregorio Marañón. CIBERCV. 28040-Madrid, Spain
| | - Francisco G Cosío
- Department of Biomedical and Health Sciences. Universidad Europea de Madrid. 28670-Madrid, Spain
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Shi L, Zhao W, Jiu Z, Guo J, Zhu Q, Sun Y, Zhu B, Chang J, Xin P. Redox-Regulated Synthetic Channels: Enabling Reversible Ion Transport by Modulating the Ion-Permeation Pathway. Angew Chem Int Ed Engl 2024:e202403667. [PMID: 38407803 DOI: 10.1002/anie.202403667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 02/25/2024] [Accepted: 02/26/2024] [Indexed: 02/27/2024]
Abstract
Natural redox-regulated channel proteins often utilize disulfide bonds as redox sensors for adaptive regulation of channel conformations in response to diverse physiological environments. In this study, we developed novel synthetic ion channels capable of reversibly switching their ion-transport capabilities by incorporating multiple disulfide bonds into artificial systems. X-ray structural analysis and electrophysiological experiments demonstrated that these disulfide-bridged molecules possess well-defined tubular cavities and can be efficiently inserted into lipid bilayers to form artificial ion channels. More importantly, the disulfide bonds in these molecules serve as redox-tunable switches to regulate the formation and disruption of ion-permeation pathways, thereby achieving a transition in the transmembrane transport process between the ON and OFF states.
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Affiliation(s)
- Linlin Shi
- State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, NMPA Key Laboratory for Research and Evaluation of Innovative Drug, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Wen Zhao
- State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, NMPA Key Laboratory for Research and Evaluation of Innovative Drug, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Zhihui Jiu
- State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, NMPA Key Laboratory for Research and Evaluation of Innovative Drug, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Jingjing Guo
- Centre in Artificial Intelligence Driven Drug Discovery, Faculty of Applied Sciences, Macao Polytechnic University, Macao, 999078, China
| | - Qiuhui Zhu
- State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, NMPA Key Laboratory for Research and Evaluation of Innovative Drug, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Yonghui Sun
- State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, NMPA Key Laboratory for Research and Evaluation of Innovative Drug, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Bo Zhu
- State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, NMPA Key Laboratory for Research and Evaluation of Innovative Drug, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Junbiao Chang
- State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, NMPA Key Laboratory for Research and Evaluation of Innovative Drug, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Pengyang Xin
- State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, NMPA Key Laboratory for Research and Evaluation of Innovative Drug, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
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3
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Qi Y, Zhang YM, Gao YN, Chen WG, Zhou T, Chang L, Zang Y, Li J. AMPK role in epilepsy: a promising therapeutic target? J Neurol 2024; 271:748-771. [PMID: 38010498 DOI: 10.1007/s00415-023-12062-w] [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: 07/21/2023] [Revised: 10/11/2023] [Accepted: 10/12/2023] [Indexed: 11/29/2023]
Abstract
Epilepsy is a complex and multifaceted neurological disorder characterized by spontaneous and recurring seizures. It poses significant therapeutic challenges due to its diverse etiology and often-refractory nature. This comprehensive review highlights the pivotal role of AMP-activated protein kinase (AMPK), a key metabolic regulator involved in cellular energy homeostasis, which may be a promising therapeutic target for epilepsy. Current therapeutic strategies such as antiseizure medication (ASMs) can alleviate seizures (up to 70%). However, 30% of epileptic patients may develop refractory epilepsy. Due to the complicated nature of refractory epilepsy, other treatment options such as ketogenic dieting, adjunctive therapy, and in limited cases, surgical interventions are employed. These therapy options are only suitable for a select group of patients and have limitations of their own. Current treatment options for epilepsy need to be improved. Emerging evidence underscores a potential association between impaired AMPK functionality in the brain and the onset of epilepsy, prompting an in-depth examination of AMPK's influence on neural excitability and ion channel regulation, both critical factors implicated in epileptic seizures. AMPK activation through agents such as metformin has shown promising antiepileptic effects in various preclinical and clinical settings. These effects are primarily mediated through the inhibition of the mTOR signaling pathway, activation of the AMPK-PI3K-c-Jun pathway, and stimulation of the PGC-1α pathway. Despite the potential of AMPK-targeted therapies, several aspects warrant further exploration, including the detailed mechanisms of AMPK's role in different brain regions, the impact of AMPK under various conditional circumstances such as neural injury and zinc toxicity, the long-term safety and efficacy of chronic metformin use in epilepsy treatment, and the potential benefits of combination therapy involving AMPK activators. Moreover, the efficacy of AMPK activators in refractory epilepsy remains an open question. This review sets the stage for further research with the aim of enhancing our understanding of the role of AMPK in epilepsy, potentially leading to the development of more effective, AMPK-targeted therapeutic strategies for this challenging and debilitating disorder.
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Affiliation(s)
- Yingbei Qi
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, Zhejiang, China
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yong-Mei Zhang
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, Zhejiang, China
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ya-Nan Gao
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- China Pharmaceutical University, Nanjing, 210009, Jiangsu, China
| | - Wen-Gang Chen
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- China Pharmaceutical University, Nanjing, 210009, Jiangsu, China
| | - Ting Zhou
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Liuliu Chang
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yi Zang
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
| | - Jia Li
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, Zhejiang, China.
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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4
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Gong Y, Liu R, Zha H, Dong D, Lu N, Yan H, Wan L, Nian Y. Analgesic Buxus alkaloids with Enhanced Selectivity for the Low-Voltage-Gated Calcium Channel Ca v 3.2 over Ca v 3.1 through a New Binding Mode. Angew Chem Int Ed Engl 2024; 63:e202313461. [PMID: 37997012 DOI: 10.1002/anie.202313461] [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: 09/18/2023] [Revised: 11/20/2023] [Accepted: 11/23/2023] [Indexed: 11/25/2023]
Abstract
Low-voltage-gated calcium channels (LVGCCs; Cav 3.1-3.3) represent promising drug targets for epilepsy, pain, and essential tremor. At present, modulators with heightened selectivity for a subtype of LVGCCs are still highly desired. In this study we explored three classes of Buxus alkaloids and identified 9(10/19)abeo-artanes Buxusemine H and Buxusemine L (BXSL) as an unprecedented type of Cav 3.2 inhibitors. Particularly, BXSL exhibited Cav 3.2 inhibition comparable to Z944, a non-subtype-selective LVGCCs inhibitor under clinical trial. While lacking specificity for Cav 3.3, BXSL showed a 30-fold selectivity of Cav 3.2 over Cav 3.1. As compared to several well-known inhibitors, the experimental and computational studies suggested BXSL exhibits a distinct binding mode to Cav 3.2, notably through the essential interaction with serine-1543 in domain III. Furthermore, BXSL showed minimal impact on various recombinant and native nociceptive ion channels, while significantly reducing the excitability of isolated mouse dorsal root ganglion neurons. Animal studies in wild-type and Cav 3.2 knock-out mice revealed that BXSL (5 mg/kg), by inhibiting Cav 3.2, exhibits an analgesic effect equivalent to Z944 (10 mg/kg) or mibefradil (10 mg/kg). Moreover, we proposed a structural rationale for the high selectivity of 9(10/19)abeo-artane-type alkaloids towards Cav 3.2 over Cav 3.1. This study introduces a novel analgesic agent and valuable molecular insight for structure-based innovative Cav 3.2 drug development.
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Affiliation(s)
- Ye Gong
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, Yunnan, P. R. China
| | - Rui Liu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, Yunnan, P. R. China
| | - Hongjing Zha
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, P. R. China
| | - Ding Dong
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, Yunnan, P. R. China
| | - Nihong Lu
- Department of Respiratory Medicine, The Third People's Hospital of Kunming, Kunming, 650041, Yunnan, P. R. China
| | - Hui Yan
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, Yunnan, P. R. China
| | - Luosheng Wan
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, P. R. China
| | - Yin Nian
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, Yunnan, P. R. China
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Bahcheli AT, Min HK, Bayati M, Zhao H, Fortuna A, Dong W, Dzneladze I, Chan J, Chen X, Guevara-Hoyer K, Dirks PB, Huang X, Reimand J. Pan-cancer ion transport signature reveals functional regulators of glioblastoma aggression. EMBO J 2024; 43:196-224. [PMID: 38177502 PMCID: PMC10897389 DOI: 10.1038/s44318-023-00016-x] [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: 05/05/2023] [Revised: 11/30/2023] [Accepted: 11/30/2023] [Indexed: 01/06/2024] Open
Abstract
Ion channels, transporters, and other ion-flux controlling proteins, collectively comprising the "ion permeome", are common drug targets, however, their roles in cancer remain understudied. Our integrative pan-cancer transcriptome analysis shows that genes encoding the ion permeome are significantly more often highly expressed in specific subsets of cancer samples, compared to pan-transcriptome expectations. To enable target selection, we identified 410 survival-associated IP genes in 33 cancer types using a machine-learning approach. Notably, GJB2 and SCN9A show prominent expression in neoplastic cells and are associated with poor prognosis in glioblastoma, the most common and aggressive brain cancer. GJB2 or SCN9A knockdown in patient-derived glioblastoma cells induces transcriptome-wide changes involving neuron projection and proliferation pathways, impairs cell viability and tumor sphere formation in vitro, perturbs tunneling nanotube dynamics, and extends the survival of glioblastoma-bearing mice. Thus, aberrant activation of genes encoding ion transport proteins appears as a pan-cancer feature defining tumor heterogeneity, which can be exploited for mechanistic insights and therapy development.
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Affiliation(s)
- Alexander T Bahcheli
- Computational Biology Program, Ontario Institute for Cancer Research, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Hyun-Kee Min
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada
| | - Masroor Bayati
- Computational Biology Program, Ontario Institute for Cancer Research, Toronto, ON, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Hongyu Zhao
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Neurosurgery and Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Alexander Fortuna
- Computational Biology Program, Ontario Institute for Cancer Research, Toronto, ON, Canada
| | - Weifan Dong
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada
| | - Irakli Dzneladze
- Computational Biology Program, Ontario Institute for Cancer Research, Toronto, ON, Canada
| | - Jade Chan
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada
| | - Xin Chen
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada
- Songjiang Research Institute, Songjiang Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Kissy Guevara-Hoyer
- Computational Biology Program, Ontario Institute for Cancer Research, Toronto, ON, Canada
- Cancer Immunomonitoring and Immuno-Mediated Pathologies Support Unit, Department of Clinical Immunology, Institute of Laboratory Medicine (IML) and Biomedical Research Foundation (IdiSCC), San Carlos Clinical Hospital, Madrid, Spain
| | - Peter B Dirks
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada
| | - Xi Huang
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada.
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada.
| | - Jüri Reimand
- Computational Biology Program, Ontario Institute for Cancer Research, Toronto, ON, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
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6
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Moreddu R. Nanotechnology and Cancer Bioelectricity: Bridging the Gap Between Biology and Translational Medicine. Adv Sci (Weinh) 2024; 11:e2304110. [PMID: 37984883 PMCID: PMC10767462 DOI: 10.1002/advs.202304110] [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] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 09/25/2023] [Indexed: 11/22/2023]
Abstract
Bioelectricity is the electrical activity that occurs within living cells and tissues. This activity is critical for regulating homeostatic cellular function and communication, and disruptions of the same can lead to a variety of conditions, including cancer. Cancer cells are known to exhibit abnormal electrical properties compared to their healthy counterparts, and this has driven researchers to investigate the potential of harnessing bioelectricity as a tool in cancer diagnosis, prognosis, and treatment. In parallel, bioelectricity represents one of the means to gain fundamental insights on how electrical signals and charges play a role in cancer insurgence, growth, and progression. This review provides a comprehensive analysis of the literature in this field, addressing the fundamentals of bioelectricity in single cancer cells, cancer cell cohorts, and cancerous tissues. The emerging role of bioelectricity in cancer proliferation and metastasis is introduced. Based on the acknowledgement that this biological information is still hard to access due to the existing gap between biological findings and translational medicine, the latest advancements in the field of nanotechnologies for cellular electrophysiology are examined, as well as the most recent developments in micro- and nano-devices for cancer diagnostics and therapy targeting bioelectricity.
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7
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Yousf S, Malla JA, Sardesai DM, Sharma S, Talukdar P, Chugh J. Mapping metabolic perturbations induced by glutathione activatable synthetic ion channels in human breast cancer cells. J Pharm Biomed Anal 2023; 235:115605. [PMID: 37531734 DOI: 10.1016/j.jpba.2023.115605] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/24/2023] [Accepted: 07/25/2023] [Indexed: 08/04/2023]
Abstract
Ion channels and transporters play key roles in various biological processes, including cell proliferation and programmed cell death. Recently, we reported that 2,4-dinitrobenzene-sulfonyl-protected N1,N3-dihexy-2-hydroxyisophthalamide (1) forms ion channels upon activation by glutathione (GSH) and results in the induction of apoptosis by depleting the intracellular GSH reservoir in cancer cells. However, the detailed molecular events leading to the induction of apoptosis by these synthetic transport systems in cancer cells still need to be uncovered. Along these lines, we investigated the alterations in cellular metabolites and the associated metabolic pathways by performing untargeted global metabolic profiling of breast cancer cells - MCF-7 - using 1H NMR-based metabolomics. The evaluation of spectral profiles from MCF-7 cells exposed to 1 and their comparison with those corresponding to untreated (control) cells identified 14 significantly perturbed signature metabolites. These metabolites belonged mostly to antioxidant defence, energy metabolism, amino acid biosynthesis, and lipid metabolism pathways and included GSH, o-phosphocholine, malate, and aspartate, to name a few. These results would help us gain deeper insights into the molecular mechanism underlying 1-mediated cytotoxicity of MCF-7 cells and eventually help identify potential novel therapeutic targets for more effective cancer management.
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Affiliation(s)
- Saleem Yousf
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
| | - Javid A Malla
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Devika M Sardesai
- Department of Biotechnology, Savitribai Phule Pune University (SPPU), Ganeshkhind, Pune 411007, India
| | - Shilpy Sharma
- Department of Biotechnology, Savitribai Phule Pune University (SPPU), Ganeshkhind, Pune 411007, India
| | - Pinaki Talukdar
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Jeetender Chugh
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
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Clemens DJ, Ye D, Wang L, Kim CSJ, Zhou W, Dotzler SM, Tester DJ, Marty I, Knollmann BC, Ackerman MJ. Cellular and electrophysiological characterization of triadin knockout syndrome using induced pluripotent stem cell-derived cardiomyocytes. Stem Cell Reports 2023; 18:1075-1089. [PMID: 37163978 PMCID: PMC10202692 DOI: 10.1016/j.stemcr.2023.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 04/07/2023] [Accepted: 04/11/2023] [Indexed: 05/12/2023] Open
Abstract
Triadin knockout syndrome (TKOS) is a malignant arrhythmia disorder caused by recessive null variants in TRDN-encoded cardiac triadin. Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) were generated from two unrelated TKOS patients and an unrelated control. CRISPR-Cas9 gene editing was used to insert homozygous TRDN-p.D18fs∗13 into a control line to generate a TKOS model (TRDN-/-). Western blot confirmed total knockout of triadin in patient-specific and TRDN-/- iPSC-CMs. iPSC-CMs from both patients revealed a prolonged action potential duration (APD) at 90% repolarization, and this was normalized by protein replacement of triadin. APD prolongation was confirmed in TRDN-/- iPSC-CMs. TRDN-/- iPSC-CMs revealed that loss of triadin underlies decreased expression and co-localization of key calcium handling proteins, slow and decreased calcium release from the sarcoplasmic reticulum, and slow inactivation of the L-type calcium channel leading to frequent cellular arrhythmias, including early and delayed afterdepolarizations and APD alternans.
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Affiliation(s)
- Daniel J Clemens
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Dan Ye
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | - Lili Wang
- Department of Medicine, Vanderbilt Center for Arrhythmia Research and Therapeutics, Nashville, TN, USA
| | - C S John Kim
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | - Wei Zhou
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | - Steven M Dotzler
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - David J Tester
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | - Isabelle Marty
- University Grenoble Alpes, INSERM U1216, CHU Grenoble Alpes, Grenoble Institute Neurosciences, 38000 Grenoble, France
| | - Bjorn C Knollmann
- Department of Medicine, Vanderbilt Center for Arrhythmia Research and Therapeutics, Nashville, TN, USA; Vanderbilt School of Medicine, Nashville, TN, USA
| | - Michael J Ackerman
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA; Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN, USA.
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9
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Roberts M, Yao S, Wei S, Jensen JT, Han L. Hormonal regulation of non-CFTR ion channels in the endocervix. F S Sci 2023; 4:163-171. [PMID: 36907435 DOI: 10.1016/j.xfss.2023.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 03/03/2023] [Accepted: 03/07/2023] [Indexed: 03/14/2023]
Abstract
OBJECTIVE To characterize ion channel expression and localization in the endocervix under different hormonal conditions using a non-human primate (NHP) primary endocervical epithelial cell model. DESIGN Experimental. SETTING University-based, translational science laboratory. INTERVENTIONS We cultured and treated conditionally reprogrammed primary rhesus macaque endocervix cells with estradiol and progesterone and measured gene expression changes for several known ion channel and ion channel regulators of mucus secreting epithelia. Using both rhesus macaque endocervical samples and human samples, we localized channels in the endocervix using immunohistochemistry (IHC). MAIN OUTCOME MEASURES Relative abundance of transcripts was evaluated using real-time PCR. Immunostaining results evaluated qualitatively. RESULTS Compared to controls, we found that estradiol increased gene expression for ANO6, NKCC1, CLCA1 and PDE4D. Progesterone downregulated gene expression for ANO6, SCNN1A, SCNN1B, NKCC1, and PDE4D (P ≤ .05). IHC confirmed endocervical cell membrane localization of ANO1, ANO6, KCNN4, LRR8CA, and NKCC1. CONCLUSION We find several ion channels and ion channel regulators that are hormonally sensitive in the endocervix. These channels therefore may play a role in the cyclic fertility changes in the endocervix and could be further investigated as targets for future fertility and contraceptive studies.
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Affiliation(s)
- Mackenzie Roberts
- Oregon National Primate Research Center, Division of Reproductive and Developmental Sciences, Portland, OR.
| | - Shan Yao
- Oregon National Primate Research Center, Division of Reproductive and Developmental Sciences, Portland, OR
| | - Shuhao Wei
- Oregon National Primate Research Center, Division of Reproductive and Developmental Sciences, Portland, OR
| | - Jeffrey T Jensen
- Oregon National Primate Research Center, Division of Reproductive and Developmental Sciences, Portland, OR; Oregon Health & Science University, Department of Obstetrics and Gynecology, Portland, OR
| | - Leo Han
- Oregon National Primate Research Center, Division of Reproductive and Developmental Sciences, Portland, OR; Oregon Health & Science University, Department of Obstetrics and Gynecology, Portland, OR
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10
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Xin P, Xu L, Dong W, Mao L, Guo J, Bi J, Zhang S, Pei Y, Chen CP. Synthetic K + Channels Constructed by Rebuilding the Core Modules of Natural K + Channels in an Artificial System. Angew Chem Int Ed Engl 2023; 62:e202217859. [PMID: 36583482 DOI: 10.1002/anie.202217859] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 12/26/2022] [Accepted: 12/29/2022] [Indexed: 12/31/2022]
Abstract
Different types of natural K+ channels share similar core modules and cation permeability characteristics. In this study, we have developed novel artificial K+ channels by rebuilding the core modules of natural K+ channels in artificial systems. All the channels displayed high selectivity for K+ over Na+ and exhibited a selectivity sequence of K+ ≈Rb+ during the transport process, which is highly consistent with the cation permeability characteristics of natural K+ channels. More importantly, these artificial channels could be efficiently inserted into cell membranes and mediate the transmembrane transport of K+ , disrupting the cellular K+ homeostasis and eventually triggering the apoptosis of cells. These findings demonstrate that, by rebuilding the core modules of natural K+ channels in artificial systems, the structures, transport behaviors, and physiological functions of natural K+ channels can be mimicked in synthetic channels.
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Affiliation(s)
- Pengyang Xin
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Linqi Xu
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Wenpei Dong
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Linlin Mao
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Jingjing Guo
- Engineering Research Centre of Applied Technology on Machine Translation and Artificial Intelligence, Macao Polytechnic University, Macao, 999078, China
| | - Jingjing Bi
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Shouwei Zhang
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Yan Pei
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Chang-Po Chen
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
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11
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Yang H, Yi J, Pang S, Ye K, Ye Z, Duan Q, Yan Z, Lian C, Yang Y, Zhu L, Qu DH, Bao C. A Light-Driven Molecular Machine Controls K + Channel Transport and Induces Cancer Cell Apoptosis. Angew Chem Int Ed Engl 2022; 61:e202204605. [PMID: 35442566 DOI: 10.1002/anie.202204605] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Indexed: 12/21/2022]
Abstract
The design of artificial ion channels with high activity, selectivity and gating function is challenging. Herein, we designed the light-driven motor molecule MC2, which provides new design criteria to overcome these challenges. MC2 forms a selective K+ channel through a single molecular transmembrane mechanism, and the light-driven rotary motion significantly accelerates ion transport, which endows the irradiated motor molecule with excellent cytotoxicity and cancer cell selectivity. Mechanistic studies reveal that the rotary motion of MC2 promotes K+ efflux, generates reactive oxygen species and eventually activates caspase-3-dependent apoptosis in cancer cells. Combined with the spatiotemporally controllable advantages of light, we believe this strategy can be exploited in the structural design and application of next-generation synthetic cation transporters for the treatment of cancer and other diseases.
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Affiliation(s)
- Huiting Yang
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Jinhao Yi
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Shihao Pang
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Kai Ye
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Zhicheng Ye
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Qi Duan
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Zexin Yan
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Cheng Lian
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Yi Yang
- Shanghai Frontier Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, Shanghai, 200237, China
| | - Linyong Zhu
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, China.,Shanghai Frontier Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, Shanghai, 200237, China
| | - Da-Hui Qu
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Chunyan Bao
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, China.,Shanghai Frontier Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, Shanghai, 200237, China
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12
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Yu X, Li C, Chang J, Wang Y, Xia W, Suo J, Guan X, Valtchev V, Yan Y, Qiu S, Fang Q. Gating Effects for Ion Transport in Three-Dimensional Functionalized Covalent Organic Frameworks. Angew Chem Int Ed Engl 2022; 61:e202200820. [PMID: 35072979 DOI: 10.1002/anie.202200820] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Indexed: 12/12/2022]
Abstract
The development of bioinspired nano/subnano-sized (<2 nm) ion channels is still considered a great challenge due to the difficulty in precisely controlling pore's internal structure and chemistry. Herein, for the first time, we report that three-dimensional functionalized covalent organic frameworks (COFs) can act as an effective nanofluidic platform for intelligent modulation of the ion transport. By strategic attachment of 12-crown-4 groups to the monomers as ion-driver door locks, we demonstrate that gating effects of functionalized COFs can be activated by lithium ions. The obtained materials exhibit an outstanding selective ion transmission performance with a high gating ratio (up to 23.6 for JUC-590), which is among the highest values in metal ion-activated solid-state nanochannels reported so far. Furthermore, JUC-590 offers high tunability, selectivity, and recyclability of ion transport proved by the experimental and simulated studies.
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Affiliation(s)
- Xiuqin Yu
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun, 130012, China
| | - Cuiyan Li
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun, 130012, China
| | - Jianhong Chang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun, 130012, China
| | - Yujie Wang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun, 130012, China
| | - Weifeng Xia
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun, 130012, China
| | - Jinquan Suo
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun, 130012, China
| | - Xinyu Guan
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun, 130012, China
| | - Valentin Valtchev
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Song Ling Rd, Qingdao, Shandong, 266101, China.,Normandie Univ, ENSICAEN, UNICAEN, CNRS, Laboratoire Catalyse et Spectrochimie, 6 Marechal Juin, 14050, Caen, France
| | - Yushan Yan
- Department of Chemical and Biomolecular Engineering, Center for Catalytic Science and Technology, University of Delaware, Newark, DE 19716, USA
| | - Shilun Qiu
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun, 130012, China
| | - Qianrong Fang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun, 130012, China
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13
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Treichel AJ, Finholm I, Knutson KR, Alcaino C, Whiteman ST, Brown MR, Matveyenko A, Wegner A, Kacmaz H, Mercado-Perez A, Bedekovicsne Gajdos G, Ordog T, Grover M, Szurzewski J, Linden DR, Farrugia G, Beyder A. Specialized Mechanosensory Epithelial Cells in Mouse Gut Intrinsic Tactile Sensitivity. Gastroenterology 2022; 162:535-547.e13. [PMID: 34688712 PMCID: PMC8792331 DOI: 10.1053/j.gastro.2021.10.026] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 08/30/2021] [Accepted: 10/12/2021] [Indexed: 01/07/2023]
Abstract
BACKGROUND AND AIMS The gastrointestinal (GI) tract extracts nutrients from ingested meals while protecting the organism from infectious agents frequently present in meals. Consequently, most animals conduct the entire digestive process within the GI tract while keeping the luminal contents entirely outside the body, separated by the tightly sealed GI epithelium. Therefore, like the skin and oral cavity, the GI tract must sense the chemical and physical properties of the its external interface to optimize its function. Specialized sensory enteroendocrine cells (EECs) in GI epithelium interact intimately with luminal contents. A subpopulation of EECs express the mechanically gated ion channel Piezo2 and are developmentally and functionally like the skin's touch sensor- the Merkel cell. We hypothesized that Piezo2+ EECs endow the gut with intrinsic tactile sensitivity. METHODS We generated transgenic mouse models with optogenetic activators in EECs and Piezo2 conditional knockouts. We used a range of reference standard and novel techniques from single cells to living animals, including single-cell RNA sequencing and opto-electrophysiology, opto-organ baths with luminal shear forces, and in vivo studies that assayed GI transit while manipulating the physical properties of luminal contents. RESULTS Piezo2+ EECs have transcriptomic features of synaptically connected, mechanosensory epithelial cells. EEC activation by optogenetics and forces led to Piezo2-dependent alterations in colonic propagating contractions driven by intrinsic circuitry, with Piezo2+ EECs detecting the small luminal forces and physical properties of the luminal contents to regulate transit times in the small and large bowel. CONCLUSIONS The GI tract has intrinsic tactile sensitivity that depends on Piezo2+ EECs and allows it to detect luminal forces and physical properties of luminal contents to modulate physiology.
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Affiliation(s)
- Anthony J. Treichel
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Isabelle Finholm
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Kaitlyn R. Knutson
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Constanza Alcaino
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Sara T. Whiteman
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Matthew R. Brown
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Aleksey Matveyenko
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Andrew Wegner
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Halil Kacmaz
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Arnaldo Mercado-Perez
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Medical Scientist Training Program, Mayo Clinic, Rochester, Minnesota
| | - Gabriella Bedekovicsne Gajdos
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Tamas Ordog
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Madhusudan Grover
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Joseph Szurzewski
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - David R. Linden
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Gianrico Farrugia
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Arthur Beyder
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota; Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota.
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14
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Montañés-Agudo P, Casini S, Aufiero S, Ernault AC, van der Made I, Pinto YM, Remme CA, Creemers EE. Inhibition of minor intron splicing reduces Na+ and Ca2+ channel expression and function in cardiomyocytes. J Cell Sci 2021; 135:273616. [PMID: 34859816 PMCID: PMC8767276 DOI: 10.1242/jcs.259191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 11/26/2021] [Indexed: 12/04/2022] Open
Abstract
Eukaryotic genomes contain a tiny subset of ‘minor class’ introns with unique sequence elements that require their own splicing machinery. These minor introns are present in certain gene families with specific functions, such as voltage-gated Na+ and voltage-gated Ca2+ channels. Removal of minor introns by the minor spliceosome has been proposed as a post-transcriptional regulatory layer, which remains unexplored in the heart. Here, we investigate whether the minor spliceosome regulates electrophysiological properties of cardiomyocytes by knocking down the essential minor spliceosome small nuclear snRNA component U6atac in neonatal rat ventricular myocytes. Loss of U6atac led to robust minor intron retention within Scn5a and Cacna1c, resulting in reduced protein levels of Nav1.5 and Cav1.2 channels. Functional consequences were studied through patch-clamp analysis, and revealed reduced Na+ and L-type Ca2+ currents after loss of U6atac. In conclusion, minor intron splicing modulates voltage-dependent ion channel expression and function in cardiomyocytes. This may be of particular relevance in situations in which minor splicing activity changes, such as in genetic diseases affecting minor spliceosome components, or in acquired diseases in which minor spliceosome components are dysregulated, such as heart failure. Summary: Knockdown of minor spliceosome component U6atac in cardiomyocytes reveals that expression of the Na+ channel Scn5a and the L-type Ca2+ channel Cacna1c critically depend on minor intron splicing.
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Affiliation(s)
- Pablo Montañés-Agudo
- Departments of Experimental Cardiology, Biostatistics and Bioinformatics, Amsterdam UMC, location AMC, Amsterdam, The Netherlands
| | - Simona Casini
- Departments of Experimental Cardiology, Biostatistics and Bioinformatics, Amsterdam UMC, location AMC, Amsterdam, The Netherlands
| | - Simona Aufiero
- Departments of Experimental Cardiology, Biostatistics and Bioinformatics, Amsterdam UMC, location AMC, Amsterdam, The Netherlands.,Clinical Epidemiology, Biostatistics and Bioinformatics, Amsterdam UMC, location AMC, Amsterdam, The Netherlands
| | - Auriane C Ernault
- Departments of Experimental Cardiology, Biostatistics and Bioinformatics, Amsterdam UMC, location AMC, Amsterdam, The Netherlands
| | - Ingeborg van der Made
- Departments of Experimental Cardiology, Biostatistics and Bioinformatics, Amsterdam UMC, location AMC, Amsterdam, The Netherlands
| | - Yigal M Pinto
- Departments of Experimental Cardiology, Biostatistics and Bioinformatics, Amsterdam UMC, location AMC, Amsterdam, The Netherlands
| | - Carol Ann Remme
- Departments of Experimental Cardiology, Biostatistics and Bioinformatics, Amsterdam UMC, location AMC, Amsterdam, The Netherlands
| | - Esther E Creemers
- Departments of Experimental Cardiology, Biostatistics and Bioinformatics, Amsterdam UMC, location AMC, Amsterdam, The Netherlands
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15
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Shah V, Patel S, Shah J. Emerging Role of Piezo Ion Channels in Cardiovascular Development. Dev Dyn 2021; 251:276-286. [PMID: 34255896 DOI: 10.1002/dvdy.401] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [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: 12/01/2020] [Revised: 06/12/2021] [Accepted: 07/09/2021] [Indexed: 12/23/2022] Open
Abstract
Mechanical cues are crucial for vascular development and the proper differentiation of various cell types. Piezo1 and Piezo2 are mechanically activated cationic channels expressed in various cell types, especially in vascular smooth muscle and endothelial cells. It is present as a transmembrane homotrimeric complex, regulating calcium influx. Local blood flow associated shear stress, in addition to blood pressure associated cell membrane stretching are key Piezo channel activators. There is rising proof, showcasing Piezo channels significance in myocytes, cardiac fibroblast, vascular tone maintenance, atherosclerosis, hypertension, NO generation, and baroreceptor reflex. Here, we review the role of Piezo channels in cardiovascular development and its associated clinical disorders. Also, emphasizing on Piezo channel modulators which might lead to novel therapies for cardiovascular diseases. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Vandit Shah
- Department of Pharmacology, L.M. College of Pharmacy, Navrangpura, Ahmedabad, Gujarat, India
| | - Sandip Patel
- Department of Pharmacology, L.M. College of Pharmacy, Navrangpura, Ahmedabad, Gujarat, India
| | - Jigna Shah
- Department of Pharmacology, Institute of Pharmacy Nirma University, Ahmedabad, Gujarat, India
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16
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Huang L, Xu G, Jiang R, Luo Y, Zuo Y, Liu J. Development of Non-opioid Analgesics Targeting Two-pore Domain Potassium Channels. Curr Neuropharmacol 2021; 20:16-26. [PMID: 33827408 PMCID: PMC9199554 DOI: 10.2174/1570159x19666210407152528] [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] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/14/2021] [Accepted: 03/24/2021] [Indexed: 02/08/2023] Open
Abstract
Two-pore domain potassium (K2P) channels are a diverse family of potassium channels. K2P channels generate background leak potassium currents to regulate cellular excitability and are thereby involved in a wide range of neurological disorders. K2P channels are modulated by a variety of physicochemical factors such as mechanical stretch, temperature, and pH. In the the peripheral nervous system (PNS), K2P channels are widely expressed in nociceptive neurons and play a critical roles in pain perception. In this review, we summarize the recent advances in the pharmacological properties of K2P channels, with a focus on the exogenous small-molecule activators targeting K2P channels. We emphasize the subtype-selectivity, cellular and in vivo pharmacological properties of all the reported small-molecule activators. The key underlying analgesic mechanisms mediated by K2P are also summarized based on the data in the literature from studies using small-molecule activators and genetic knock-out animals. We discuss advantages and limitations of the translational perspectives of K2P in pain medicine and provide outstanding questions for future studies in the end.
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Affiliation(s)
- Lu Huang
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610000, Sichuan. China
| | - Guangyin Xu
- Department of Physiology and Neurobiology, Institute of Neuroscience, Medical College of Soochow University, Suzhou, 215123, Jiangsu. China
| | - Ruotian Jiang
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610000, Sichuan. China
| | - Yuncheng Luo
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610000, Sichuan. China
| | - Yunxia Zuo
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610000, Sichuan. China
| | - Jin Liu
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610000, Sichuan. China
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17
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Gillespie D. Simulating diffusion from a cluster of point sources using propagation integrals. Eur Biophys J 2020; 49:385-393. [PMID: 32488299 DOI: 10.1007/s00249-020-01438-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/30/2020] [Accepted: 05/17/2020] [Indexed: 11/25/2022]
Abstract
A computational methodology to simulate the diffusion of ions from point sources (e.g., ion channels) is described. The outlined approach computes the ion concentration from a cluster of many ion channels at pre-specified locations as a function of time using the theory of propagation integrals. How the channels' open/closed states evolve in time does not need to be known at the start of the simulation, but can be updated on-the-fly as the simulation goes along. The technique uses analytic formulas for the solutions of the diffusion equation for three common geometries: (1) ions diffusing from a membrane (planar symmetry); (2) ions diffusing into a narrow cleft for effective two-dimensional diffusion (cylindrical symmetry); and (3) ions diffusing into open space like the cytosol (spherical symmetry). Because these formulas are exact solutions valid for arbitrarily long timesteps, no spatial or time discretizations are necessary. The only discrete locations are where the ion concentration is computed, and the only discrete timesteps are when the channels' open/closed states are updated. Beyond pure diffusion, the technique is generalized to the Excess Buffer Approximation of ion chelation to give an analytic solution of this approximation of the full reaction/diffusion system. Both the pure diffusion and the diffusion/buffering algorithms scale linearly with the number of channels and the number of ion concentration locations.
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Affiliation(s)
- Dirk Gillespie
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL, USA.
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18
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LoRusso E, Hickman JJ, Guo X. Ion channel dysfunction and altered motoneuron excitability in ALS. Neurol Disord Epilepsy J 2019; 3:124. [PMID: 32313901 PMCID: PMC7170321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Dysregulated excitability is a hallmark of Amyotrophic Lateral Sclerosis (ALS) pathology both in ALS research models and in clinical settings. This primarily results from the dysfunction of Na+, K+, and Ca2+ ion channels responsible for maintaining neuronal thresholds and executing signal transduction or synaptic transmission. The exact dysfunction that each of these ion channel currents display in ALS pathology can vary between different ALS models, mainly induced pluripotent stem cell (iPSC) derived human motoneurons and ALS mouse models. Moreover, results can vary further across ALS mutations and between different developmental periods of these disease models. This review attempts to gather observations regarding ion channel dysfunction contributing to both hyperexcitable and hypoexcitable phenotypes in ALS motoneurons both in vivo and in vitro, so as to assess their potential as therapeutic targets.
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19
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Vigneault P, Naud P, Qi X, Xiao J, Villeneuve L, Davis DR, Nattel S. Calcium-dependent potassium channels control proliferation of cardiac progenitor cells and bone marrow-derived mesenchymal stem cells. J Physiol 2018; 596:2359-2379. [PMID: 29574723 DOI: 10.1113/jp275388] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 02/26/2018] [Indexed: 12/26/2022] Open
Abstract
KEY POINTS Ex vivo proliferated c-Kit+ endogenous cardiac progenitor cells (eCPCs) obtained from mouse and human cardiac tissues have been reported to express a wide range of functional ion channels. In contrast to previous reports in cultured c-Kit+ eCPCs, we found that ion currents were minimal in freshly isolated cells. However, inclusion of free Ca2+ intracellularly revealed a prominent inwardly rectifying current identified as the intermediate conductance Ca2+ -activated K+ current (KCa3.1) Electrical function of both c-Kit+ eCPCs and bone marrow-derived mesenchymal stem cells is critically governed by KCa3.1 calcium-dependent potassium channels. Ca2+ -induced increases in KCa3.1 conductance are necessary to optimize membrane potential during Ca2+ entry. Membrane hyperpolarization due to KCa3.1 activation maintains the driving force for Ca2+ entry that activates stem cell proliferation. Cardiac disease downregulates KCa3.1 channels in resident cardiac progenitor cells. Alterations in KCa3.1 may have pathophysiological and therapeutic significance in regenerative medicine. ABSTRACT Endogenous c-Kit+ cardiac progenitor cells (eCPCs) and bone marrow (BM)-derived mesenchymal stem cells (MSCs) are being developed for cardiac regenerative therapy, but a better understanding of their physiology is needed. Here, we addressed the unknown functional role of ion channels in freshly isolated eCPCs and expanded BM-MSCs using patch-clamp, microfluorometry and confocal microscopy. Isolated c-Kit+ eCPCs were purified from dog hearts by immunomagnetic selection. Ion currents were barely detectable in freshly isolated c-Kit+ eCPCs with buffering of intracellular calcium (Ca2+i ). Under conditions allowing free intracellular Ca2+ , freshly isolated c-Kit+ eCPCs and ex vivo proliferated BM-MSCs showed prominent voltage-independent conductances that were sensitive to intermediate-conductance K+ -channel (KCa3.1 current, IKCa3.1 ) blockers and corresponding gene (KCNN4)-expression knockdown. Depletion of Ca2+i induced membrane-potential (Vmem ) depolarization, while store-operated Ca2+ entry (SOCE) hyperpolarized Vmem in both cell types. The hyperpolarizing SOCE effect was substantially reduced by IKCa3.1 or SOCE blockade (TRAM-34, 2-APB), and IKCa3.1 blockade (TRAM-34) or KCNN4-knockdown decreased the Ca2+ entry resulting from SOCE. IKCa3.1 suppression reduced c-Kit+ eCPC and BM-MSC proliferation, while significantly altering the profile of cyclin expression. IKCa3.1 was reduced in c-Kit+ eCPCs isolated from dogs with congestive heart failure (CHF), along with corresponding KCNN4 mRNA. Under perforated-patch conditions to maintain physiological [Ca2+ ]i , c-Kit+ eCPCs from CHF dogs had less negative resting membrane potentials (-58 ± 7 mV) versus c-Kit+ eCPCs from control dogs (-73 ± 3 mV, P < 0.05), along with slower proliferation. Our study suggests that Ca2+ -induced increases in IKCa3.1 are necessary to optimize membrane potential during the Ca2+ entry that activates progenitor cell proliferation, and that alterations in KCa3.1 may have pathophysiological and therapeutic significance in regenerative medicine.
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Affiliation(s)
- Patrick Vigneault
- Research Center and Department of Medicine, Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada
| | - Patrice Naud
- Research Center and Department of Medicine, Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada
| | - Xiaoyan Qi
- Research Center and Department of Medicine, Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada
| | - Jiening Xiao
- Research Center and Department of Medicine, Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada
| | - Louis Villeneuve
- Research Center and Department of Medicine, Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada
| | - Darryl R Davis
- University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Stanley Nattel
- Research Center and Department of Medicine, Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada.,Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada.,Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
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20
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Valinsky WC, Touyz RM, Shrier A. Aldosterone, SGK1, and ion channels in the kidney. Clin Sci (Lond) 2018; 132:173-83. [PMID: 29352074 DOI: 10.1042/CS20171525] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 12/15/2017] [Accepted: 12/19/2017] [Indexed: 12/14/2022]
Abstract
Hyperaldosteronism, a common cause of hypertension, is strongly connected to Na+, K+, and Mg2+ dysregulation. Owing to its steroidal structure, aldosterone is an active transcriptional modifier when bound to the mineralocorticoid receptor (MR) in cells expressing the enzyme 11β-hydroxysteroid dehydrogenase 2, such as those comprising the aldosterone-sensitive distal nephron (ASDN). One such up-regulated protein, the ubiquitous serum and glucocorticoid regulated kinase 1 (SGK1), has the capacity to modulate the surface expression and function of many classes of renal ion channels, including those that transport Na+ (ENaC), K+ (ROMK/BK), Ca2+ (TRPV4/5/6), Mg2+ (TRPM7/6), and Cl− (ClC-K, CFTR). Here, we discuss the mechanisms by which ASDN expressed channels are up-regulated by SGK1, while highlighting newly discovered pathways connecting aldosterone to nonselective cation channels that are permeable to Mg2+ (TRPM7) or Ca2+ (TRPV4).
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21
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Affiliation(s)
- Thomas E DeCoursey
- Department of Physiology and Biophysics, Rush University, Chicago, IL, 60612, USA
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22
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Sutphin BS, Boczek NJ, Barajas-Martínez H, Hu D, Ye D, Tester DJ, Antzelevitch C, Ackerman MJ. Molecular and Functional Characterization of Rare CACNA1C Variants in Sudden Unexplained Death in the Young. CONGENIT HEART DIS 2016; 11:683-692. [PMID: 27218670 DOI: 10.1111/chd.12371] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 02/03/2016] [Accepted: 03/18/2016] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Perturbations in the CACNA1C-encoded L-type calcium channel α-subunit have been linked recently to heritable arrhythmia syndromes, including Timothy syndrome, Brugada syndrome, early repolarization syndrome, and long QT syndrome. These heritable arrhythmia syndromes may serve as a pathogenic basis for autopsy-negative sudden unexplained death in the young (SUDY). However, the contribution of CACNA1C mutations to SUDY is unknown. OBJECTIVE We set out to determine the spectrum, prevalence, and pathophysiology of rare CACNA1C variants in SUDY. METHODS Mutational analysis of CACNA1C was conducted in 82 SUDY cases using polymerase chain reaction, denaturing high-performance liquid chromatography, and direct sequencing. Identified variants were engineered using site-directed mutagenesis, and heterologously expressed in TSA-201 or HEK293 cells. RESULTS Two SUDY cases (2.4%) harbored functional variants in CACNA1C. The E850del and N2091S variants involve highly conserved residues and localize to the II-III linker and C-terminus, respectively. Although observed in publically available exome databases, both variants confer abnormal CaV 1.2 electrophysiological characteristics. Examination of the electrophysiological properties revealed the E850del mutation in CACNA1C led to a 95% loss-of-function in ICa , and the N2091S variant led to a 105% gain-of-function in ICa. Additionally, N2091S led to minor kinetic alterations including a -3.4 mV shift in V1/2 of activation. CONCLUSION This study provides molecular and functional evidence that rare CACNA1C genetic variants may contribute to the underlying pathogenic basis for some cases of SUDY in either a gain or loss-of-function mechanism.
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Affiliation(s)
- Brittan S Sutphin
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland, Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minn, USA
| | - Nicole J Boczek
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland, Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minn, USA
| | | | - Dan Hu
- Department of Molecular Genetics, Masonic Medical Research Laboratory, Utica, N.Y., USA
| | - Dan Ye
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland, Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minn, USA
| | - David J Tester
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland, Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minn, USA
| | - Charles Antzelevitch
- Department of Molecular Genetics, Masonic Medical Research Laboratory, Utica, N.Y., USA
| | - Michael J Ackerman
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland, Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minn, USA.,Departments of Medicine (Division of Cardiovascular Diseases) and Pediatrics (Division of Pediatric Cardiology), Mayo Clinic, Rochester, Minn, USA
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23
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Meiselbach H, Vogel N, Langlhofer G, Stangl S, Schleyer B, Bahnassawy L, Sticht H, Breitinger HG, Becker CM, Villmann C. Single expressed glycine receptor domains reconstitute functional ion channels without subunit-specific desensitization behavior. J Biol Chem 2014; 289:29135-47. [PMID: 25143388 DOI: 10.1074/jbc.m114.559138] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cys loop receptors are pentameric arrangements of independent subunits that assemble into functional ion channels. Each subunit shows a domain architecture. Functional ion channels can be reconstituted even from independent, nonfunctional subunit domains, as shown previously for GlyRα1 receptors. Here, we demonstrate that this reconstitution is not restricted to α1 but can be transferred to other members of the Cys loop receptor family. A nonfunctional GlyR subunit, truncated at the intracellular TM3-4 loop by a premature stop codon, can be complemented by co-expression of the missing tail portion of the receptor. Compared with α1 subunits, rescue by domain complementation was less efficient when GlyRα3 or the GABAA/C subunit ρ1 was used. If truncation disrupted an alternative splicing cassette within the intracellular TM3-4 loop of α3 subunits, which also regulates receptor desensitization, functional rescue was not possible. When α3 receptors were restored by complementation using domains with and without the spliced insert, no difference in desensitization was found. In contrast, desensitization properties could even be transferred between α1/α3 receptor chimeras harboring or lacking the α3 splice cassette proving that functional rescue depends on the integrity of the alternative splicing cassette in α3. Thus, an intact α3 splicing cassette in the TM3-4 loop environment is indispensable for functional rescue, and the quality of receptor restoration can be assessed from desensitization properties.
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Affiliation(s)
| | - Nico Vogel
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander University Erlangen-Nürnberg, Fahrstrasse 17, 91054 Erlangen, Germany
| | - Georg Langlhofer
- the Institute for Clinical Neurobiology, University of Würzburg, Versbacherstrasse 5, 97078 Würzburg, Germany, and
| | - Sabine Stangl
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander University Erlangen-Nürnberg, Fahrstrasse 17, 91054 Erlangen, Germany
| | - Barbara Schleyer
- the Institute for Clinical Neurobiology, University of Würzburg, Versbacherstrasse 5, 97078 Würzburg, Germany, and
| | - Lamia'a Bahnassawy
- the Biochemistry Department, German University Cairo, New Cairo City, Cairo 11835, Egypt
| | | | - Hans-Georg Breitinger
- the Biochemistry Department, German University Cairo, New Cairo City, Cairo 11835, Egypt
| | - Cord-Michael Becker
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander University Erlangen-Nürnberg, Fahrstrasse 17, 91054 Erlangen, Germany
| | - Carmen Villmann
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander University Erlangen-Nürnberg, Fahrstrasse 17, 91054 Erlangen, Germany, the Institute for Clinical Neurobiology, University of Würzburg, Versbacherstrasse 5, 97078 Würzburg, Germany, and
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24
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Ko EA, Jin BJ, Namkung W, Ma T, Thiagarajah JR, Verkman AS. Chloride channel inhibition by a red wine extract and a synthetic small molecule prevents rotaviral secretory diarrhoea in neonatal mice. Gut 2014; 63:1120-9. [PMID: 24052273 PMCID: PMC4048772 DOI: 10.1136/gutjnl-2013-305663] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Rotavirus is the most common cause of severe secretory diarrhoea in infants and young children globally. The rotaviral enterotoxin, NSP4, has been proposed to stimulate calcium-activated chloride channels (CaCC) on the apical plasma membrane of intestinal epithelial cells. We previously identified red wine and small molecule CaCC inhibitors. OBJECTIVE To investigate the efficacy of a red wine extract and a synthetic small molecule, CaCCinh-A01, in inhibiting intestinal CaCCs and rotaviral diarrhoea. DESIGN Inhibition of CaCC-dependent current was measured in T84 cells and mouse ileum. The effectiveness of an orally administered wine extract and CaCCinh-A01 in inhibiting diarrhoea in vivo was determined in a neonatal mouse model of rotaviral infection. RESULTS Screening of ∼150 red wines revealed a Cabernet Sauvignon that inhibited CaCC current in T84 cells with IC50 at a ∼1:200 dilution, and higher concentrations producing 100% inhibition. A >1 kdalton wine extract prepared by dialysis, which retained full inhibition activity, blocked CaCC current in T84 cells and mouse intestine. In rotavirus-inoculated mice, oral administration of the wine extract prevented diarrhoea by inhibition of intestinal fluid secretion without affecting rotaviral infection. The wine extract did not inhibit the cystic fibrosis chloride channel (CFTR) in cell cultures, nor did it prevent watery stools in neonatal mice administered cholera toxin, which activates CFTR-dependent fluid secretion. CaCCinh-A01 also inhibited rotaviral diarrhoea. CONCLUSIONS Our results support a pathogenic role for enterocyte CaCCs in rotaviral diarrhoea and demonstrate the antidiarrhoeal action of CaCC inhibition by an alcohol-free, red wine extract and by a synthetic small molecule.
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Affiliation(s)
- Eun-A Ko
- Departments of Medicine and Physiology, University of California, San Francisco, California, USA
| | - Byung-Ju Jin
- Departments of Medicine and Physiology, University of California, San Francisco, California, USA
| | - Wan Namkung
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, Korea
| | - Tonghui Ma
- Department of Physiology, Dalian Medical University, Dalian, China
| | - Jay R. Thiagarajah
- Department of Gastroenterology, Hepatology and Nutrition, Children’s Hospital, Boston, Harvard Medical School, Boston, Massachusetts, USA
| | - A. S. Verkman
- Departments of Medicine and Physiology, University of California, San Francisco, California, USA
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25
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Tillman TS, Seyoum E, Mowrey DD, Xu Y, Tang P. ELIC-α7 Nicotinic acetylcholine receptor (α7nAChR) chimeras reveal a prominent role of the extracellular-transmembrane domain interface in allosteric modulation. J Biol Chem 2014; 289:13851-7. [PMID: 24695730 PMCID: PMC4022858 DOI: 10.1074/jbc.m113.524611] [Citation(s) in RCA: 20] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 03/10/2014] [Indexed: 01/08/2023] Open
Abstract
The native α7 nicotinic acetylcholine receptor (α7nAChR) is a homopentameric ligand-gated ion channel mediating fast synaptic transmission and is of pharmaceutical interest for treatment of numerous disorders. The transmembrane domain (TMD) of α7nAChR has been identified as a target for positive allosteric modulators (PAMs), but it is unclear whether modulation occurs through changes entirely within the TMD or changes involving both the TMD and the extracellular domain (ECD)-TMD interface. In this study, we constructed multiple chimeras using the TMD of human α7nAChR and the ECD of a prokaryotic homolog, ELIC, which is not sensitive to these modulators, and for which a high resolution structure has been solved. Functional ELIC-α7nAChR (EA) chimeras were obtained when their ECD-TMD interfaces were modified to resemble either the ELIC interface (EAELIC) or α7nAChR interface (EAα7). Both EAα7 and EAELIC show similar activation response and desensitization characteristics, but only EAα7 retained the unique pharmacology of α7nAChR evoked by PAMs, including potentiation by ivermectin, PNU-120596, and TQS, as well as activation by 4BP-TQS. This study suggests that PAM modulation through the TMD has a more stringent requirement at the ECD-TMD interface than agonist activation.
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Affiliation(s)
| | | | - David D Mowrey
- From the Departments of Anesthesiology, Computational and Systems Biology, and
| | - Yan Xu
- From the Departments of Anesthesiology, Pharmacology and Chemical Biology, Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260
| | - Pei Tang
- From the Departments of Anesthesiology, Computational and Systems Biology, and Pharmacology and Chemical Biology,
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26
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Williams SM, Chandran AV, Vijayabaskar MS, Roy S, Balaram H, Vishveshwara S, Vijayan M, Chatterji D. A histidine aspartate ionic lock gates the iron passage in miniferritins from Mycobacterium smegmatis. J Biol Chem 2014; 289:11042-11058. [PMID: 24573673 PMCID: PMC4036245 DOI: 10.1074/jbc.m113.524421] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 02/24/2014] [Indexed: 11/06/2022] Open
Abstract
Dps (DNA-binding protein from starved cells) are dodecameric assemblies belonging to the ferritin family that can bind DNA, carry out ferroxidation, and store iron in their shells. The ferritin-like trimeric pore harbors the channel for the entry and exit of iron. By representing the structure of Dps as a network we have identified a charge-driven interface formed by a histidine aspartate cluster at the pore interface unique to Mycobacterium smegmatis Dps protein, MsDps2. Site-directed mutagenesis was employed to generate mutants to disrupt the charged interactions. Kinetics of iron uptake/release of the wild type and mutants were compared. Crystal structures were solved at a resolution of 1.8-2.2 Å for the various mutants to compare structural alterations vis à vis the wild type protein. The substitutions at the pore interface resulted in alterations in the side chain conformations leading to an overall weakening of the interface network, especially in cases of substitutions that alter the charge at the pore interface. Contrary to earlier findings where conserved aspartate residues were found crucial for iron release, we propose here that in the case of MsDps2, it is the interplay of negative-positive potentials at the pore that enables proper functioning of the protein. In similar studies in ferritins, negative and positive patches near the iron exit pore were found to be important in iron uptake/release kinetics. The unique ionic cluster in MsDps2 makes it a suitable candidate to act as nano-delivery vehicle, as these gated pores can be manipulated to exhibit conformations allowing for slow or fast rates of iron release.
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Affiliation(s)
| | - Anu V Chandran
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Mahalingam S Vijayabaskar
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom, and
| | - Sourav Roy
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| | - Hemalatha Balaram
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| | | | - Mamannamana Vijayan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Dipankar Chatterji
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India,; Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India.
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27
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Baek JH, Rubinstein M, Scheuer T, Trimmer JS. Reciprocal changes in phosphorylation and methylation of mammalian brain sodium channels in response to seizures. J Biol Chem 2014; 289:15363-73. [PMID: 24737319 DOI: 10.1074/jbc.m114.562785] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium (Nav) channels initiate action potentials in brain neurons and are primary therapeutic targets for anti-epileptic drugs controlling neuronal hyperexcitability in epilepsy. The molecular mechanisms underlying abnormal Nav channel expression, localization, and function during development of epilepsy are poorly understood but can potentially result from altered posttranslational modifications (PTMs). For example, phosphorylation regulates Nav channel gating, and has been proposed to contribute to acquired insensitivity to anti-epileptic drugs exhibited by Nav channels in epileptic neurons. However, whether changes in specific brain Nav channel PTMs occur acutely in response to seizures has not been established. Here, we show changes in PTMs of the major brain Nav channel, Nav1.2, after acute kainate-induced seizures. Mass spectrometry-based proteomic analyses of Nav1.2 purified from the brains of control and seizure animals revealed a significant down-regulation of phosphorylation at nine sites, primarily located in the interdomain I-II linker, the region of Nav1.2 crucial for phosphorylation-dependent regulation of activity. Interestingly, Nav1.2 in the seizure samples contained methylated arginine (MeArg) at three sites. These MeArgs were adjacent to down-regulated sites of phosphorylation, and Nav1.2 methylation increased after seizure. Phosphorylation and MeArg were not found together on the same tryptic peptide, suggesting reciprocal regulation of these two PTMs. Coexpression of Nav1.2 with the primary brain arginine methyltransferase PRMT8 led to a surprising 3-fold increase in Nav1.2 current. Reciprocal regulation of phosphorylation and MeArg of Nav1.2 may underlie changes in neuronal Nav channel function in response to seizures and also contribute to physiological modulation of neuronal excitability.
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Affiliation(s)
- Je-Hyun Baek
- From the Department of Neurobiology, Physiology, and Behavior and
| | - Moran Rubinstein
- the Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195-7280
| | - Todd Scheuer
- the Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195-7280
| | - James S Trimmer
- From the Department of Neurobiology, Physiology, and Behavior and the Department of Physiology and Membrane Biology, University of California, Davis, California 95616 and
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Mukherjee A, Mueller GM, Kinlough CL, Sheng N, Wang Z, Mustafa SA, Kashlan OB, Kleyman TR, Hughey RP. Cysteine palmitoylation of the γ subunit has a dominant role in modulating activity of the epithelial sodium channel. J Biol Chem 2014; 289:14351-9. [PMID: 24692558 DOI: 10.1074/jbc.m113.526020] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The epithelial sodium channel (ENaC) is composed of three homologous subunits (α, β, and γ) with cytoplasmic N and C termini. Our previous work revealed that two cytoplasmic Cys residues in the β subunit, βCys-43 and βCys-557, are Cys-palmitoylated. ENaCs with mutant βC43A/C557A exhibit normal surface expression but enhanced Na(+) self-inhibition and reduced channel open probability. Although the α subunit is not palmitoylated, we now show that the two cytoplasmic Cys residues in the γ subunit are palmitoylated. ENaCs with mutant γC33A, γC41A, or γC33A/C41A exhibit reduced activity compared with wild type channels but normal surface expression and normal levels of α and γ subunit-activating cleavage. These mutant channels have significantly enhanced Na(+) self-inhibition and reduced open probability compared with wild type ENaCs. Channel activity was enhanced by co-expression with the palmitoyltransferase DHHC2 that also co-immunoprecipitates with ENaCs. Secondary structure prediction of the N terminus of the γ subunit places γCys-33 within an α-helix and γCys-44 on a coil before the first transmembrane domain within a short tract that includes a well conserved His-Gly motif, where mutations have been associated with altered channel gating. Our current and previous results suggest that palmitoylation of the β and γ subunits of ENaCs enhances interactions of their respective cytoplasmic domains with the plasma membrane and stabilizes the open state of the channel. Comparison of activities of channels lacking palmitoylation sites in individual or multiple subunits revealed that γ subunit palmitoylation has a dominant role over β subunit palmitoylation in modulating ENaC gating.
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Affiliation(s)
| | | | - Carol L Kinlough
- From the Renal-Electrolyte Division, Department of Medicine, and
| | - Nan Sheng
- From the Renal-Electrolyte Division, Department of Medicine, and
| | - Zhijian Wang
- From the Renal-Electrolyte Division, Department of Medicine, and
| | - S Atif Mustafa
- From the Renal-Electrolyte Division, Department of Medicine, and
| | - Ossama B Kashlan
- From the Renal-Electrolyte Division, Department of Medicine, and
| | - Thomas R Kleyman
- From the Renal-Electrolyte Division, Department of Medicine, and Department of Cell Biology,
| | - Rebecca P Hughey
- From the Renal-Electrolyte Division, Department of Medicine, and Department of Cell Biology, Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
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29
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Dai G, Sherpa T, Varnum MD. Alternative splicing governs cone cyclic nucleotide-gated (CNG) channel sensitivity to regulation by phosphoinositides. J Biol Chem 2014; 289:13680-90. [PMID: 24675082 DOI: 10.1074/jbc.m114.562272] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Precursor mRNA encoding CNGA3 subunits of cone photoreceptor cyclic nucleotide-gated (CNG) channels undergoes alternative splicing, generating isoforms differing in the N-terminal cytoplasmic region of the protein. In humans, four variants arise from alternative splicing, but the functional significance of these changes has been a persistent mystery. Heterologous expression of the four possible CNGA3 isoforms alone or with CNGB3 subunits did not reveal significant differences in basic channel properties. However, inclusion of optional exon 3, with or without optional exon 5, produced heteromeric CNGA3 + CNGB3 channels exhibiting an ∼2-fold greater shift in K1/2,cGMP after phosphatidylinositol 4,5-biphosphate or phosphatidylinositol 3,4,5-trisphosphate application compared with channels lacking the sequence encoded by exon 3. We have previously identified two structural features within CNGA3 that support phosphoinositides (PIPn) regulation of cone CNG channels: N- and C-terminal regulatory modules. Specific mutations within these regions eliminated PIPn sensitivity of CNGA3 + CNGB3 channels. The exon 3 variant enhanced the component of PIPn regulation that depends on the C-terminal region rather than the nearby N-terminal region, consistent with an allosteric effect on PIPn sensitivity because of altered N-C coupling. Alternative splicing of CNGA3 occurs in multiple species, although the exact variants are not conserved across CNGA3 orthologs. Optional exon 3 appears to be unique to humans, even compared with other primates. In parallel, we found that a specific splice variant of canine CNGA3 removes a region of the protein that is necessary for high sensitivity to PIPn. CNGA3 alternative splicing may have evolved, in part, to tune the interactions between cone CNG channels and membrane-bound phosphoinositides.
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Affiliation(s)
- Gucan Dai
- From the Department of Integrative Physiology and Neuroscience
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30
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Möykkynen T, Coleman SK, Semenov A, Keinänen K. The N-terminal domain modulates α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor desensitization. J Biol Chem 2014; 289:13197-205. [PMID: 24652293 DOI: 10.1074/jbc.m113.526301] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
AMPA receptors are tetrameric glutamate-gated ion channels that mediate fast synaptic neurotransmission in mammalian brain. Their subunits contain a two-lobed N-terminal domain (NTD) that comprises over 40% of the mature polypeptide. The NTD is not obligatory for the assembly of tetrameric receptors, and its functional role is still unclear. By analyzing full-length and NTD-deleted GluA1-4 AMPA receptors expressed in HEK 293 cells, we found that the removal of the NTD leads to a significant reduction in receptor transport to the plasma membrane, a higher steady state-to-peak current ratio of glutamate responses, and strongly increased sensitivity to glutamate toxicity in cell culture. Further analyses showed that NTD-deleted receptors display both a slower onset of desensitization and a faster recovery from desensitization of agonist responses. Our results indicate that the NTD promotes the biosynthetic maturation of AMPA receptors and, for membrane-expressed channels, enhances the stability of the desensitized state. Moreover, these findings suggest that interactions of the NTD with extracellular/synaptic ligands may be able to fine-tune AMPA receptor-mediated responses, in analogy with the allosteric regulatory role demonstrated for the NTD of NMDA receptors.
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Affiliation(s)
- Tommi Möykkynen
- From the Division of Biochemistry and Biotechnology, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
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31
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Schredelseker J, Paz A, López CJ, Altenbach C, Leung CS, Drexler MK, Chen JN, Hubbell WL, Abramson J. High resolution structure and double electron-electron resonance of the zebrafish voltage-dependent anion channel 2 reveal an oligomeric population. J Biol Chem 2014; 289:12566-77. [PMID: 24627492 DOI: 10.1074/jbc.m113.497438] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In recent years, there has been a vast increase in structural and functional understanding of VDAC1, but VDAC2 and -3 have been understudied despite having many unique phenotypes. One reason for the paucity of structural and biochemical characterization of the VDAC2 and -3 isoforms stems from the inability of obtaining purified, functional protein. Here we demonstrate the expression, isolation, and basic characterization of zebrafish VDAC2 (zfVDAC2). Further, we resolved the structure of zfVDAC2 at 2.8 Å resolution, revealing a crystallographic dimer. The dimer orientation was confirmed in solution by double electron-electron resonance spectroscopy and by cross-linking experiments disclosing a dimer population of ∼20% in lauryldimethine amine oxide detergent micelles, whereas in lipidic bicelles a higher population of dimeric and higher order oligomers species were observed. The present study allows for a more accurate structural comparison between VDAC2 and its better-studied counterpart VDAC1.
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Senning EN, Collins MD, Stratiievska A, Ufret-Vincenty CA, Gordon SE. Regulation of TRPV1 ion channel by phosphoinositide (4,5)-bisphosphate: the role of membrane asymmetry. J Biol Chem 2014; 289:10999-11006. [PMID: 24599956 DOI: 10.1074/jbc.m114.553180] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Membrane asymmetry is essential for generating second messengers that act in the cytosol and for trafficking of membrane proteins and membrane lipids, but the role of asymmetry in regulating membrane protein function remains unclear. Here we show that the signaling lipid phosphoinositide 4,5-bisphosphate (PI(4,5)P2) has opposite effects on the function of TRPV1 ion channels depending on which leaflet of the cell membrane it resides in. We observed potentiation of capsaicin-activated TRPV1 currents by PI(4,5)P2 in the intracellular leaflet of the plasma membrane but inhibition of capsaicin-activated currents when PI(4,5)P2 was in both leaflets of the membrane, although much higher concentrations of PI(4,5)P2 in the extracellular leaflet were required for inhibition compared with the concentrations of PI(4,5)P2 in the intracellular leaflet that produced activation. Patch clamp fluorometry using a synthetic PI(4,5)P2 whose fluorescence reports its concentration in the membrane indicates that PI(4,5)P2 must incorporate into the extracellular leaflet for its inhibitory effects to be observed. The asymmetry-dependent effect of PI(4,5)P2 may resolve the long standing controversy about whether PI(4,5)P2 is an activator or inhibitor of TRPV1. Our results also underscore the importance of membrane asymmetry and the need to consider its influence when studying membrane proteins reconstituted into synthetic bilayers.
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Affiliation(s)
- Eric N Senning
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington 98195-7290 and
| | - Marcus D Collins
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington 98195-7290 and
| | - Anastasiia Stratiievska
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington 98195-7290 and; Laboratory of Biophysics of Ion Channels, Department of General Physiology of the Nervous System, Bogomoletz Institute of Physiology, International Center for Molecular Physiology, 01024 Kyiv, Ukraine
| | - Carmen A Ufret-Vincenty
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington 98195-7290 and
| | - Sharona E Gordon
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington 98195-7290 and.
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Bill A, Hall ML, Borawski J, Hodgson C, Jenkins J, Piechon P, Popa O, Rothwell C, Tranter P, Tria S, Wagner T, Whitehead L, Gaither LA. Small molecule-facilitated degradation of ANO1 protein: a new targeting approach for anticancer therapeutics. J Biol Chem 2014; 289:11029-11041. [PMID: 24599954 PMCID: PMC4036244 DOI: 10.1074/jbc.m114.549188] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
ANO1, a calcium-activated chloride channel, is highly expressed and amplified in human cancers and is a critical survival factor in these cancers. The ANO1 inhibitor CaCCinh-A01 decreases proliferation of ANO1-amplified cell lines; however, the mechanism of action remains elusive. We explored the mechanism behind the inhibitory effect of CaCCinh-A01 on cell proliferation using a combined experimental and in silico approach. We show that inhibition of ANO1 function is not sufficient to diminish proliferation of ANO1-dependent cancer cells. We report that CaCCinh-A01 reduces ANO1 protein levels by facilitating endoplasmic reticulum-associated, proteasomal turnover of ANO1. Washout of CaCCinh-A01 rescued ANO1 protein levels and resumed cell proliferation. Proliferation of newly derived CaCCinh-A01-resistant cell pools was not affected by CaCCinh-A01 as compared with the parental cells. Consistently, CaCCinh-A01 failed to reduce ANO1 protein levels in these cells, whereas ANO1 currents were still inhibited by CaCCinh-A01, indicating that CaCCinh-A01 inhibits cell proliferation by reducing ANO1 protein levels. Furthermore, we employed in silico methods to elucidate novel biological functions of ANO1 inhibitors. Specifically, we derived a pharmacophore model to describe inhibitors capable of promoting ANO1 degradation and report new inhibitors of ANO1-dependent cell proliferation. In summary, our data demonstrate that inhibition of the channel activity of ANO1 is not sufficient to inhibit ANO1-dependent cell proliferation, indicating that the role of ANO1 in cancer only partially depends on its function as a channel. Our results provide an impetus for gaining a deeper understanding of ANO1 modulation in cells and introduce a new targeting approach for antitumor therapy in ANO1-amplified cancers.
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Affiliation(s)
- Anke Bill
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Michelle Lynn Hall
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Jason Borawski
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Catherine Hodgson
- Novartis Institutes for Biomedical Research, Horsham, West Sussex, RH12 5AB, United Kingdom, and
| | - Jeremy Jenkins
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Philippe Piechon
- the Novartis Institutes for Biomedical Research, Basel CH-4002, Switzerland
| | - Oana Popa
- Novartis Institutes for Biomedical Research, Horsham, West Sussex, RH12 5AB, United Kingdom, and
| | | | - Pamela Tranter
- Novartis Institutes for Biomedical Research, Horsham, West Sussex, RH12 5AB, United Kingdom, and
| | - Scott Tria
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Trixie Wagner
- the Novartis Institutes for Biomedical Research, Basel CH-4002, Switzerland
| | - Lewis Whitehead
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - L Alex Gaither
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139,.
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Noam Y, Ehrengruber MU, Koh A, Feyen P, Manders EMM, Abbott GW, Wadman WJ, Baram TZ. Filamin A promotes dynamin-dependent internalization of hyperpolarization-activated cyclic nucleotide-gated type 1 (HCN1) channels and restricts Ih in hippocampal neurons. J Biol Chem 2014; 289:5889-903. [PMID: 24403084 PMCID: PMC3937658 DOI: 10.1074/jbc.m113.522060] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [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: 09/24/2013] [Revised: 12/27/2013] [Indexed: 11/06/2022] Open
Abstract
The actin-binding protein filamin A (FLNa) regulates neuronal migration during development, yet its roles in the mature brain remain largely obscure. Here, we probed the effects of FLNa on the regulation of ion channels that influence neuronal properties. We focused on the HCN1 channels that conduct Ih, a hyperpolarization-activated current crucial for shaping intrinsic neuronal properties. Whereas regulation of HCN1 channels by FLNa has been observed in melanoma cell lines, its physiological relevance to neuronal function and the underlying cellular pathways that govern this regulation remain unknown. Using a combination of mutational, pharmacological, and imaging approaches, we find here that FLNa facilitates a selective and reversible dynamin-dependent internalization of HCN1 channels in HEK293 cells. This internalization is accompanied by a redistribution of HCN1 channels on the cell surface, by accumulation of the channels in endosomal compartments, and by reduced Ih density. In hippocampal neurons, expression of a truncated dominant-negative FLNa enhances the expression of native HCN1. Furthermore, acute abrogation of HCN1-FLNa interaction in neurons, with the use of decoy peptides that mimic the FLNa-binding domain of HCN1, abolishes the punctate distribution of HCN1 channels in neuronal cell bodies, augments endogenous Ih, and enhances the rebound-response ("voltage-sag") of the neuronal membrane to transient hyperpolarizing events. Together, these results support a major function of FLNa in modulating ion channel abundance and membrane trafficking in neurons, thereby shaping their biophysical properties and function.
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Affiliation(s)
- Yoav Noam
- From the Departments of Anatomy/Neurobiology and Pediatrics and
| | | | - Annie Koh
- From the Departments of Anatomy/Neurobiology and Pediatrics and
| | | | - Erik M. M. Manders
- van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, 1098XH Amsterdam, The Netherlands
| | - Geoffrey W. Abbott
- Pharmacology, University of California at Irvine, Irvine, California 92697-4475 and
| | | | - Tallie Z. Baram
- From the Departments of Anatomy/Neurobiology and Pediatrics and
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Lorca RA, Stamnes SJ, Pillai MK, Hsiao JJ, Wright ME, England SK. N-terminal isoforms of the large-conductance Ca²⁺-activated K⁺ channel are differentially modulated by the auxiliary β1-subunit. J Biol Chem 2014; 289:10095-103. [PMID: 24569989 DOI: 10.1074/jbc.m113.521526] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The large-conductance Ca(2+)-activated K(+) (BK(Ca)) channel is essential for maintaining the membrane in a hyperpolarized state, thereby regulating neuronal excitability, smooth muscle contraction, and secretion. The BK(Ca) α-subunit has three predicted initiation codons that generate proteins with N-terminal ends starting with the amino acid sequences MANG, MSSN, or MDAL. Because the N-terminal region and first transmembrane domain of the α-subunit are required for modulation by auxiliary β1-subunits, we examined whether β1 differentially modulates the N-terminal BK(Ca) α-subunit isoforms. In the absence of β1, all isoforms had similar single-channel conductances and voltage-dependent activation. However, whereas β1 did not modulate the voltage-activation curve of MSSN, β1 induced a significant leftward shift of the voltage activation curves of both the MDAL and MANG isoforms. These shifts, of which the MDAL was larger, occurred at both 10 μM and 100 μM Ca(2+). The β1-subunit increased the open dwell times of all three isoforms and decreased the closed dwell times of MANG and MDAL but increased the closed dwell times of MSSN. The distinct modulation of voltage activation by the β1-subunit may be due to the differential effect of β1 on burst duration and interburst intervals observed among these isoforms. Additionally, we observed that the related β2-subunit induced comparable leftward shifts in the voltage-activation curves of all three isoforms, indicating that the differential modulation of these isoforms was specific to β1. These findings suggest that the relative expression of the N-terminal isoforms can fine-tune BK(Ca) channel activity in cells, highlighting a novel mechanism of BK(Ca) channel regulation.
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Affiliation(s)
- Ramón A Lorca
- From the Department of Obstetrics and Gynecology, Washington University in St. Louis School of Medicine, St. Louis, Missouri 63110 and
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36
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Jensen CS, Watanabe S, Rasmussen HB, Schmitt N, Olesen SP, Frost NA, Blanpied TA, Misonou H. Specific sorting and post-Golgi trafficking of dendritic potassium channels in living neurons. J Biol Chem 2014; 289:10566-10581. [PMID: 24569993 DOI: 10.1074/jbc.m113.534495] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Proper membrane localization of ion channels is essential for the function of neuronal cells. Particularly, the computational ability of dendrites depends on the localization of different ion channels in specific subcompartments. However, the molecular mechanisms that control ion channel localization in distinct dendritic subcompartments are largely unknown. Here, we developed a quantitative live cell imaging method to analyze protein sorting and post-Golgi vesicular trafficking. We focused on two dendritic voltage-gated potassium channels that exhibit distinct localizations: Kv2.1 in proximal dendrites and Kv4.2 in distal dendrites. Our results show that Kv2.1 and Kv4.2 channels are sorted into two distinct populations of vesicles at the Golgi apparatus. The targeting of Kv2.1 and Kv4.2 vesicles occurred by distinct mechanisms as evidenced by their requirement for specific peptide motifs, cytoskeletal elements, and motor proteins. By live cell and super-resolution imaging, we identified a novel trafficking machinery important for the localization of Kv2.1 channels. Particularly, we identified non-muscle myosin II as an important factor in Kv2.1 trafficking. These findings reveal that the sorting of ion channels at the Golgi apparatus and their subsequent trafficking by unique molecular mechanisms are crucial for their specific localizations within dendrites.
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Affiliation(s)
- Camilla Stampe Jensen
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark; Department of Neural and Pain Sciences, University of Maryland, Baltimore, Maryland 21201
| | - Shoji Watanabe
- Unit for Brain Pathology, Graduate School of Brain Science, Doshisha University, Kyoto 619-02225, Japan
| | - Hanne Borger Rasmussen
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Nicole Schmitt
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Søren-Peter Olesen
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Nicholas A Frost
- Department of Physiology, University of Maryland, Baltimore, Maryland 21201
| | - Thomas A Blanpied
- Department of Physiology, University of Maryland, Baltimore, Maryland 21201
| | - Hiroaki Misonou
- Department of Neural and Pain Sciences, University of Maryland, Baltimore, Maryland 21201; Unit for Brain Pathology, Graduate School of Brain Science, Doshisha University, Kyoto 619-02225, Japan.
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Chen X, Sun W, Gianaris NG, Riley AM, Cummins TR, Fehrenbacher JC, Obukhov AG. Furanocoumarins are a novel class of modulators for the transient receptor potential vanilloid type 1 (TRPV1) channel. J Biol Chem 2014; 289:9600-10. [PMID: 24569998 DOI: 10.1074/jbc.m113.536862] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Furanocoumarin imperatorin is the major active component of Angelica dahurica root extracts, widely used in traditional medicine to treat headache, toothache, and orbital eye pain. In this study, we investigated the mechanisms that may underlie the pain-relieving effects of the compound. We found that imperatorin significantly inhibited formalin- and capsaicin-induced nocifensive responses but did not alter baseline thermal withdrawal thresholds in the rat. We established that imperatorin is a weak agonist of TRPV1, a channel implicated in detecting several noxious stimuli, exhibiting a 50% effective concentration (EC50) of 12.6 ± 3.2 μM. A specific TRPV1 antagonist, JNJ-17203212 (0.5 μM), potently inhibited imperatorin-induced TRPV1 activation. Site-directed mutagenesis studies revealed that imperatorin most likely acted via a site adjacent to or overlapping with the TRPV1 capsaicin-binding site. TRPV1 recovery from desensitization was delayed in the presence of imperatorin. Conversely, imperatorin sensitized TRPV1 to acid activation but did not affect the current amplitude and/or the activation-inactivation properties of Na(v)1.7, a channel important for transmission of nociceptive information. Thus, our data indicate that furanocoumarins represent a novel group of TRPV1 modulators that may become important lead compounds in the drug discovery process aimed at developing new treatments for pain management.
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Affiliation(s)
- Xingjuan Chen
- From the Departments of Cellular and Integrative Physiology and
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Kamat S, Yeola S, Zhang W, Bianchi L, Driscoll M. NRA-2, a nicalin homolog, regulates neuronal death by controlling surface localization of toxic Caenorhabditis elegans DEG/ENaC channels. J Biol Chem 2014; 289:11916-11926. [PMID: 24567339 DOI: 10.1074/jbc.m113.533695] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hyperactivated DEG/ENaCs induce neuronal death through excessive cation influx and disruption of intracellular calcium homeostasis. Caenorhabditis elegans DEG/ENaC MEC-4 is hyperactivated by the (d) mutation and induces death of touch neurons. The analogous substitution in MEC-10 (MEC-10(d)) co-expressed in the same neurons is only mildly neurotoxic. We exploited the lower toxicity of MEC-10(d) to identify RNAi knockdowns that enhance neuronal death. We report here that knock-out of the C. elegans nicalin homolog NRA-2 enhances MEC-10(d)-induced neuronal death. Cell biological assays in C. elegans neurons show that NRA-2 controls the distribution of MEC-10(d) between the endoplasmic reticulum and the cell surface. Electrophysiological experiments in Xenopus oocytes support this notion and suggest that control of channel distribution by NRA-2 is dependent on the subunit composition. We propose that nicalin/NRA-2 functions in a quality control mechanism to retain mutant channels in the endoplasmic reticulum, influencing the extent of neuronal death. Mammalian nicalin may have a similar role in DEG/ENaC biology, therefore influencing pathological conditions like ischemia.
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Affiliation(s)
- Shaunak Kamat
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
| | - Shrutika Yeola
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
| | - Wenying Zhang
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
| | - Laura Bianchi
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, Florida 33136.
| | - Monica Driscoll
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854.
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Stelmashenko O, Compan V, Browne LE, North RA. Ectodomain movements of an ATP-gated ion channel (P2X2 receptor) probed by disulfide locking. J Biol Chem 2014; 289:9909-17. [PMID: 24515105 PMCID: PMC3975035 DOI: 10.1074/jbc.m113.542811] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ectodomain of the P2X receptor is formed mainly from two- or three-stranded β-sheets provided symmetrically by each of the three subunits. These enclose a central cavity that is closed off furthest from the plasma membrane (the turret) and that joins with the transmembrane helices to form the ion permeation pathway. Comparison of closed and open crystal structures indicates that ATP binds in a pocket positioned between strands provided by different subunits and that this flexes the β-sheets of the lower body and enlarges the central cavity: this pulls apart the outer ends of the transmembrane helices and thereby opens an aperture, or gate, where they intersect within the membrane bilayer. In the present work, we examined this opening model by introducing pairs of cysteines into the rat P2X2 receptor that might form disulfide bonds within or between subunits. Receptors were expressed in human embryonic kidney cells, and disulfide formation was assessed by observing the effect of dithiothreitol on currents evoked by ATP. Substitutions in the turret (P90C, P89C/S97C), body wall (S65C/S190C, S65C/D315C) and the transmembrane domains (V48C/I328C, V51C/I328C, S54C/I328C) strongly inhibited ATP-evoked currents prior to reduction with dithiothreitol. Western blotting showed that these channels also formed predominately as dimers and/or trimers rather than monomers. The results strongly support the channel opening mechanism proposed on the basis of available crystal structures.
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McCoy JG, Rusinova R, Kim DM, Kowal J, Banerjee S, Jaramillo Cartagena A, Thompson AN, Kolmakova-Partensky L, Stahlberg H, Andersen OS, Nimigean CM. A KcsA/MloK1 chimeric ion channel has lipid-dependent ligand-binding energetics. J Biol Chem 2014; 289:9535-46. [PMID: 24515111 DOI: 10.1074/jbc.m113.543389] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Cyclic nucleotide-modulated ion channels play crucial roles in signal transduction in eukaryotes. The molecular mechanism by which ligand binding leads to channel opening remains poorly understood, due in part to the lack of a robust method for preparing sufficient amounts of purified, stable protein required for structural and biochemical characterization. To overcome this limitation, we designed a stable, highly expressed chimeric ion channel consisting of the transmembrane domains of the well characterized potassium channel KcsA and the cyclic nucleotide-binding domains of the prokaryotic cyclic nucleotide-modulated channel MloK1. This chimera demonstrates KcsA-like pH-sensitive activity which is modulated by cAMP, reminiscent of the dual modulation in hyperpolarization-activated and cyclic nucleotide-gated channels that display voltage-dependent activity that is also modulated by cAMP. Using this chimeric construct, we were able to measure for the first time the binding thermodynamics of cAMP to an intact cyclic nucleotide-modulated ion channel using isothermal titration calorimetry. The energetics of ligand binding to channels reconstituted in lipid bilayers are substantially different from those observed in detergent micelles, suggesting that the conformation of the chimera's transmembrane domain is sensitive to its (lipid or lipid-mimetic) environment and that ligand binding induces conformational changes in the transmembrane domain. Nevertheless, because cAMP on its own does not activate these chimeric channels, cAMP binding likely has a smaller energetic contribution to gating than proton binding suggesting that there is only a small difference in cAMP binding energy between the open and closed states of the channel.
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Rasmussen JE, Sheridan JT, Polk W, Davies CM, Tarran R. Cigarette smoke-induced Ca2+ release leads to cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction. J Biol Chem 2014; 289:7671-81. [PMID: 24448802 DOI: 10.1074/jbc.m113.545137] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chronic obstructive pulmonary disease affects 64 million people and is currently the fourth leading cause of death worldwide. Chronic obstructive pulmonary disease includes both emphysema and chronic bronchitis, and in the case of chronic bronchitis represents an inflammatory response of the airways that is associated with mucus hypersecretion and obstruction of small airways. Recently, it has emerged that exposure to cigarette smoke (CS) leads to an inhibition of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel, causing airway surface liquid dehydration, which may play a role in the development of chronic bronchitis. CS rapidly clears CFTR from the plasma membrane and causes it to be deposited into aggresome-like compartments. However, little is known about the mechanism(s) responsible for the internalization of CFTR following CS exposure. Our studies revealed that CS triggered a rise in cytoplasmic Ca(2+) that may have emanated from lysosomes. Furthermore, chelation of cytoplasmic Ca(2+), but not inhibition of protein kinases/phosphatases, prevented CS-induced CFTR internalization. The macrolide antibiotic bafilomycin A1 inhibited CS-induced Ca(2+) release and prevented CFTR clearance from the plasma membrane, further linking cytoplasmic Ca(2+) and CFTR internalization. We hypothesize that CS-induced Ca(2+) release prevents normal sorting/degradation of CFTR and causes internalized CFTR to reroute to aggresomes. Our data provide mechanistic insight into the potentially deleterious effects of CS on airway epithelia and outline a hitherto unrecognized signaling event triggered by CS that may affect the long term transition of the lung into a hyper-inflammatory/dehydrated environment.
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Li J, Zhuo M, Pei L, Rajagopal M, Yu ASL. Comprehensive cysteine-scanning mutagenesis reveals Claudin-2 pore-lining residues with different intrapore locations. J Biol Chem 2014; 289:6475-6484. [PMID: 24436330 DOI: 10.1074/jbc.m113.536888] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The first extracellular loop (ECL1) of claudins forms paracellular pores in the tight junction that determine ion permselectivity. We aimed to map the pore-lining residues of claudin-2 by comprehensive cysteine-scanning mutagenesis of ECL1. We screened 45 cysteine mutations within the ECL1 by expression in polyclonal Madin-Darby canine kidney II Tet-Off cells and found nine mutants that displayed a significant decrease of conductance after treatment with the thiol-reactive reagent 2-(trimethylammonium)ethyl methanethiosulfonate, indicating the location of candidate pore-lining residues. Next, we stably expressed these candidates in monoclonal Madin-Darby canine kidney I Tet-Off cells and exposed them to thiol-reactive reagents. The maximum degree of inhibition of conductance, size selectivity of degree of inhibition, and size dependence of the kinetics of reaction were used to deduce the location of residues within the pore. Our data support the following sequence of pore-lining residues located from the narrowest to the widest part of the pore: Ser(68), Ser(47), Thr(62)/Ile(66), Thr(56), Thr(32)/Gly(45), and Met(52). The paracellular pore appears to primarily be lined by polar side chains, as expected for a predominantly aqueous environment. Furthermore, our results strongly suggest the existence of a continuous sequence of residues in the ECL1 centered around Asp(65)-Ser(68) that form a major part of the lining of the pore.
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Affiliation(s)
- Jiahua Li
- Division of Nephrology and Hypertension and the Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas 66160; Department of Medicine, John H. Stroger, Jr. Hospital of Cook County, Chicago, Illinois 60612
| | - Min Zhuo
- Division of Nephrology and Hypertension and the Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas 66160
| | - Lei Pei
- Division of Nephrology and Hypertension and the Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas 66160; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas 66160
| | - Madhumitha Rajagopal
- Division of Nephrology and Hypertension and the Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas 66160
| | - Alan S L Yu
- Division of Nephrology and Hypertension and the Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas 66160; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas 66160.
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Abstract
N-type and P/Q-type calcium channels are documented players in the regulation of synaptic function; however, the mechanisms underlying their expression and cellular targeting are poorly understood. Ankyrin polypeptides are essential for normal integral membrane protein expression in a number of cell types, including neurons, cardiomyocytes, epithelia, secretory cells, and erythrocytes. Ankyrin dysfunction has been linked to defects in integral protein expression, abnormal cellular function, and disease. Here, we demonstrate that ankyrin-B associates with Cav2.1 and Cav2.2 in cortex, cerebellum, and brain stem. Additionally, using in vitro and in vivo techniques, we demonstrate that ankyrin-B, via its membrane-binding domain, associates with a highly conserved motif in the DII/III loop domain of Cav2.1 and Cav2.2. Further, we demonstrate that this domain is necessary for proper targeting of Cav2.1 and Cav2.2 in a heterologous system. Finally, we demonstrate that mutation of a single conserved tyrosine residue in the ankyrin-binding motif of both Cav2.1 (Y797E) and Cav2.2 (Y788E) results in loss of association with ankyrin-B in vitro and in vivo. Collectively, our findings identify an interaction between ankyrin-B and both Cav2.1 and Cav2.2 at the amino acid level that is necessary for proper Cav2.1 and Cav2.2 targeting in vivo.
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44
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Velisetty P, Chalamalasetti SV, Chakrapani S. Structural basis for allosteric coupling at the membrane-protein interface in Gloeobacter violaceus ligand-gated ion channel (GLIC). J Biol Chem 2013; 289:3013-25. [PMID: 24338475 DOI: 10.1074/jbc.m113.523050] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ligand binding at the extracellular domain of pentameric ligand-gated ion channels initiates a relay of conformational changes that culminates at the gate within the transmembrane domain. The interface between the two domains is a key structural entity that governs gating. Molecular events in signal transduction at the interface are poorly defined because of its intrinsically dynamic nature combined with functional modulation by membrane lipid and water vestibules. Here we used electron paramagnetic resonance spectroscopy to delineate protein motions underlying Gloeobacter violaceus ligand-gated ion channel gating in a membrane environment and report the interface conformation in the closed and the desensitized states. Extensive intrasubunit interactions were observed in the closed state that are weakened upon desensitization and replaced by newer intersubunit contacts. Gating involves major rearrangements of the interfacial loops, accompanied by reorganization of the protein-lipid-water interface. These structural changes may serve as targets for modulation of gating by lipids, alcohols, and amphipathic drug molecules.
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Affiliation(s)
- Phanindra Velisetty
- From the Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4970
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45
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Lukacs V, Rives JM, Sun X, Zakharian E, Rohacs T. Promiscuous activation of transient receptor potential vanilloid 1 (TRPV1) channels by negatively charged intracellular lipids: the key role of endogenous phosphoinositides in maintaining channel activity. J Biol Chem 2013; 288:35003-13. [PMID: 24158445 PMCID: PMC3853253 DOI: 10.1074/jbc.m113.520288] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [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: 09/18/2013] [Revised: 10/18/2013] [Indexed: 11/06/2022] Open
Abstract
The regulation of the heat- and capsaicin-activated transient receptor potential vanilloid 1 (TRPV1) channels by phosphoinositides is controversial. Data in cellular systems support the dependence of TRPV1 activity on phosphoinositides. The purified TRPV1, however, was recently shown to be fully functional in artificial liposomes in the absence of phosphoinositides. Here, we show that several other negatively charged phospholipids, including phosphatidylglycerol, can also support TRPV1 activity in excised patches at high concentrations. When we incorporated TRPV1 into planar lipid bilayers consisting of neutral lipids, capsaicin-induced activity depended on phosphatidylinositol 4,5-bisphosphate. We also found that TRPV1 activity in excised patches ran down and that MgATP reactivated the channel. Inhibition of phosphatidylinositol 4-kinases or enzymatic removal of phosphatidylinositol abolished this effect of MgATP, suggesting that it activated TRPV1 by generating endogenous phosphoinositides. We conclude that endogenous phosphoinositides are positive cofactors for TRPV1 activity. Our data highlight the importance of specificity in lipid regulation of ion channels and may reconcile discordant data obtained in various experimental settings.
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Affiliation(s)
- Viktor Lukacs
- From the Department of Pharmacology and Physiology, Rutgers New Jersey Medical School, Newark, New Jersey 07103 and
| | - Jan-Michael Rives
- From the Department of Pharmacology and Physiology, Rutgers New Jersey Medical School, Newark, New Jersey 07103 and
| | - Xiaohui Sun
- Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine, Peoria, Illinois 61605
| | - Eleonora Zakharian
- Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine, Peoria, Illinois 61605
| | - Tibor Rohacs
- From the Department of Pharmacology and Physiology, Rutgers New Jersey Medical School, Newark, New Jersey 07103 and
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Schneider N, Cordeiro S, Machtens JP, Braams S, Rauen T, Fahlke C. Functional properties of the retinal glutamate transporters GLT-1c and EAAT5. J Biol Chem 2013; 289:1815-24. [PMID: 24307171 DOI: 10.1074/jbc.m113.517177] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the mammalian retina, glutamate uptake is mediated by members of a family of glutamate transporters known as "excitatory amino acid transporters (EAATs)." Here we cloned and functionally characterized two retinal EAATs from mouse, the GLT-1/EAAT2 splice variant GLT-1c, and EAAT5. EAATs are glutamate transporters and anion-selective ion channels, and we used heterologous expression in mammalian cells, patch-clamp recordings and noise analysis to study and compare glutamate transport and anion channel properties of both EAAT isoforms. We found GLT-1c to be an effective glutamate transporter with high affinity for Na(+) and glutamate that resembles original GLT-1/EAAT2 in all tested functional aspects. EAAT5 exhibits glutamate transport rates too low to be accurately measured in our experimental system, with significantly lower affinities for Na(+) and glutamate than GLT-1c. Non-stationary noise analysis demonstrated that GLT-1c and EAAT5 also differ in single-channel current amplitudes of associated anion channels. Unitary current amplitudes of EAAT5 anion channels turned out to be approximately twice as high as single-channel amplitudes of GLT-1c. Moreover, at negative potentials open probabilities of EAAT5 anion channels were much larger than for GLT-1c. Our data illustrate unique functional properties of EAAT5, being a low-affinity and low-capacity glutamate transport system, with an anion channel optimized for anion conduction in the negative voltage range.
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Affiliation(s)
- Nicole Schneider
- From the Institute of Complex Systems, Zelluläre Biophysik, Forschungszentrum Jülich, Leo-Brandt-Straβe, 52428 Jülich, Germany
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47
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El Hachmane MF, Rees KA, Veale EL, Sumbayev VV, Mathie A. Enhancement of TWIK-related acid-sensitive potassium channel 3 (TASK3) two-pore domain potassium channel activity by tumor necrosis factor α. J Biol Chem 2013; 289:1388-401. [PMID: 24307172 DOI: 10.1074/jbc.m113.500033] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
TASK3 two-pore domain potassium (K2P) channels are responsible for native leak K channels in many cell types which regulate cell resting membrane potential and excitability. In addition, TASK3 channels contribute to the regulation of cellular potassium homeostasis. Because TASK3 channels are important for cell viability, having putative roles in both neuronal apoptosis and oncogenesis, we sought to determine their behavior under inflammatory conditions by investigating the effect of TNFα on TASK3 channel current. TASK3 channels were expressed in tsA-201 cells, and the current through them was measured using whole cell voltage clamp recordings. We show that THP-1 human myeloid leukemia monocytes, co-cultured with hTASK3-transfected tsA-201 cells, can be activated by the specific Toll-like receptor 7/8 activator, R848, to release TNFα that subsequently enhances hTASK3 current. Both hTASK3 and mTASK3 channel activity is increased by incubation with recombinant TNFα (10 ng/ml for 2-15 h), but other K2P channels (hTASK1, hTASK2, hTREK1, and hTRESK) are unaffected. This enhancement by TNFα is not due to alterations in levels of channel expression at the membrane but rather to an alteration in channel gating. The enhancement by TNFα can be blocked by extracellular acidification but persists for mutated TASK3 (H98A) channels that are no longer acid-sensitive even in an acidic extracellular environment. TNFα action on TASK3 channels is mediated through the intracellular C terminus of the channel. Furthermore, it occurs through the ASK1 pathway and is JNK- and p38-dependent. In combination, TNFα activation and TASK3 channel activity can promote cellular apoptosis.
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Affiliation(s)
- Mickael-F El Hachmane
- From the Medway School of Pharmacy, University of Kent, Central Avenue, Chatham Maritime, ME4 4TB Kent, United Kingdom
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48
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Rothwell SW, Stansfeld PJ, Bragg L, Verkhratsky A, North RA. Direct gating of ATP-activated ion channels (P2X2 receptors) by lipophilic attachment at the outer end of the second transmembrane domain. J Biol Chem 2013; 289:618-26. [PMID: 24273165 PMCID: PMC3887190 DOI: 10.1074/jbc.m113.529099] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ionic pore of the P2X receptor passes through the central axis of six transmembrane (TM) helices, two from each of three subunits. Val(48) and Ile(328) are at the outer end of TM1 and TM2, respectively. Homology models of the open and closed states of P2X2 indicate that pore opening is associated with a large lateral displacement of Ile(328). In addition, molecular dynamics simulations suggest that lipids enter the interstices between the outer ends of the TM domains. The P2X2(I328C) receptor was activated by propyl-methanethiosulfonate (MTS) as effectively as by ATP, but cysteine substitutions elsewhere in TM2 had no such effect. Other lipophilic MTS compounds (methyl, ethyl, and tert-butylethyl) had a similar effect but not polar MTS. The properties of the conducting pathway opened by covalent attachment of propyl-MTS were the same as those opened by ATP, with respect to unitary conductance, rectification, and permeability of N-methyl-d-glucamine. The ATP-binding residue Lys(69) was not required for the action of propyl-MTS, although propyl-MTS did not open P2X2(K308A/I328C) receptors. The propyl-MTS did not open P2X2 receptors in which the Val(48) side chain was removed (P2X2(V48G/I328C)). The results suggest that an interaction between Val(48) and Ile(328) stabilizes the closed channel and that this is broken by covalent attachment of a larger lipophilic moiety at the I328C receptors. Lipid intercalation between the separating TM domains during channel opening would be facilitated in P2X2(I328C) receptors with attached propyl-MTS. The results are consistent with the channel opening mechanism proposed on the basis of closed and open crystal structures and permit the refinement of the position of the TMs within the bilayer.
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49
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Zubcevic L, Bavro VN, Muniz JRC, Schmidt MR, Wang S, De Zorzi R, Venien-Bryan C, Sansom MSP, Nichols CG, Tucker SJ. Control of KirBac3.1 potassium channel gating at the interface between cytoplasmic domains. J Biol Chem 2013; 289:143-51. [PMID: 24257749 PMCID: PMC3879539 DOI: 10.1074/jbc.m113.501833] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
KirBac channels are prokaryotic homologs of mammalian inwardly rectifying potassium (Kir) channels, and recent structures of KirBac3.1 have provided important insights into the structural basis of gating in Kir channels. In this study, we demonstrate that KirBac3.1 channel activity is strongly pH-dependent, and we used x-ray crystallography to determine the structural changes that arise from an activatory mutation (S205L) located in the cytoplasmic domain (CTD). This mutation stabilizes a novel energetically favorable open conformation in which changes at the intersubunit interface in the CTD also alter the electrostatic potential of the inner cytoplasmic cavity. These results provide a structural explanation for the activatory effect of this mutation and provide a greater insight into the role of the CTD in Kir channel gating.
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Affiliation(s)
- Lejla Zubcevic
- From the Biological Physics Group, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
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50
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Andersen MN, Krzystanek K, Petersen F, Bomholtz SH, Olesen SP, Abriel H, Jespersen T, Rasmussen HB. A phosphoinositide 3-kinase (PI3K)-serum- and glucocorticoid-inducible kinase 1 (SGK1) pathway promotes Kv7.1 channel surface expression by inhibiting Nedd4-2 protein. J Biol Chem 2013; 288:36841-54. [PMID: 24214981 DOI: 10.1074/jbc.m113.525931] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Epithelial cell polarization involves several kinase signaling cascades that eventually divide the surface membrane into an apical and a basolateral part. One kinase, which is activated during the polarization process, is phosphoinositide 3-kinase (PI3K). In MDCK cells, the basolateral potassium channel Kv7.1 requires PI3K activity for surface-expression during the polarization process. Here, we demonstrate that Kv7.1 surface expression requires tonic PI3K activity as PI3K inhibition triggers endocytosis of these channels in polarized MDCK. Pharmacological inhibition of SGK1 gave similar results as PI3K inhibition, whereas overexpression of constitutively active SGK1 overruled it, suggesting that SGK1 is the primary downstream target of PI3K in this process. Furthermore, knockdown of the ubiquitin ligase Nedd4-2 overruled PI3K inhibition, whereas a Nedd4-2 interaction-deficient Kv7.1 mutant was resistant to both PI3K and SGK1 inhibition. Altogether, these data suggest that a PI3K-SGK1 pathway stabilizes Kv7.1 surface expression by inhibiting Nedd4-2-dependent endocytosis and thereby demonstrates that Nedd4-2 is a key regulator of Kv7.1 localization and turnover in epithelial cells.
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Affiliation(s)
- Martin Nybo Andersen
- From The Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark and
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