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Jovanovic M, Marini JC. Update on the Genetics of Osteogenesis Imperfecta. Calcif Tissue Int 2024:10.1007/s00223-024-01266-5. [PMID: 39127989 DOI: 10.1007/s00223-024-01266-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Accepted: 07/22/2024] [Indexed: 08/12/2024]
Abstract
Osteogenesis imperfecta (OI) is a heterogeneous heritable skeletal dysplasia characterized by bone fragility and deformity, growth deficiency, and other secondary connective tissue defects. OI is now understood as a collagen-related disorder caused by defects of genes whose protein products interact with collagen for folding, post-translational modification, processing and trafficking, affecting bone mineralization and osteoblast differentiation. This review provides the latest updates on genetics of OI, including new developments in both dominant and rare OI forms, as well as the signaling pathways involved in OI pathophysiology. There is a special emphasis on discoveries of recessive mutations in TENT5A, MESD, KDELR2 and CCDC134 whose causality of OI types XIX, XX, XXI and XXI, respectively, is now established and expends the complexity of mechanisms underlying OI to overlap LRP5/6 and MAPK/ERK pathways. We also review in detail new discoveries connecting the known OI types to each other, which may underlie an eventual understanding of a final common pathway in OI cellular and bone biology.
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Affiliation(s)
- Milena Jovanovic
- Section on Heritable Disorders of Bone and Extracellular Matrix, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
- Section on Adolescent Bone and Body Composition, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Joan C Marini
- Section on Heritable Disorders of Bone and Extracellular Matrix, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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2
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Kang H, Lee CJ. Transmembrane proteins with unknown function (TMEMs) as ion channels: electrophysiological properties, structure, and pathophysiological roles. Exp Mol Med 2024; 56:850-860. [PMID: 38556553 PMCID: PMC11059273 DOI: 10.1038/s12276-024-01206-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 12/27/2023] [Accepted: 01/19/2024] [Indexed: 04/02/2024] Open
Abstract
A transmembrane (TMEM) protein with an unknown function is a type of membrane-spanning protein expressed in the plasma membrane or the membranes of intracellular organelles. Recently, several TMEM proteins have been identified as functional ion channels. The structures and functions of these proteins have been extensively studied over the last two decades, starting with TMEM16A (ANO1). In this review, we provide a summary of the electrophysiological properties of known TMEM proteins that function as ion channels, such as TMEM175 (KEL), TMEM206 (PAC), TMEM38 (TRIC), TMEM87A (GolpHCat), TMEM120A (TACAN), TMEM63 (OSCA), TMEM150C (Tentonin3), and TMEM43 (Gapjinc). Additionally, we examine the unique structural features of these channels compared to those of other well-known ion channels. Furthermore, we discuss the diverse physiological roles of these proteins in lysosomal/endosomal/Golgi pH regulation, intracellular Ca2+ regulation, spatial memory, cell migration, adipocyte differentiation, and mechanical pain, as well as their pathophysiological roles in Parkinson's disease, cancer, osteogenesis imperfecta, infantile hypomyelination, cardiomyopathy, and auditory neuropathy spectrum disorder. This review highlights the potential for the discovery of novel ion channels within the TMEM protein family and the development of new therapeutic targets for related channelopathies.
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Affiliation(s)
- Hyunji Kang
- Center for Cognition and Sociality, Life Science Cluster, Institute for Basic Science (IBS), 55 Expo-ro, Yuseong-gu, Daejeon, 34126, Republic of Korea
| | - C Justin Lee
- Center for Cognition and Sociality, Life Science Cluster, Institute for Basic Science (IBS), 55 Expo-ro, Yuseong-gu, Daejeon, 34126, Republic of Korea.
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Xiong FR, Lu J, Zhu JJ, Zhao RX, Zhang YC, Yang JK. KCNH6 is essential for insulin secretion by regulating intracellular ER Ca 2+ store. FASEB J 2024; 38:e23490. [PMID: 38363581 DOI: 10.1096/fj.202302194rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 01/17/2024] [Accepted: 01/30/2024] [Indexed: 02/17/2024]
Abstract
Appropriate Ca2+ concentration in the endoplasmic reticulum (ER), modulating cytosolic Ca2+ signal, serves significant roles in physiological function of pancreatic β cells. To maintaining ER homeostasis, Ca2+ movement across the ER membrane is always accompanied by a simultaneous K+ flux in the opposite direction. KCNH6 was proven to modulate insulin secretion by controlling plasma membrane action potential duration and intracellular Ca2+ influx. Meanwhile, the specific function of KCNH6 in pancreatic β-cells remains unclear. In this study, we found that KCNH6 exhibited mainly ER localization and Kcnh6 β-cell-specific knockout (βKO) mice suffered from abnormal glucose tolerance and impaired insulin secretion in adulthood. ER Ca2+ store was overloaded in islets of βKO mice, which contributed to ER stress and ER stress-induced apoptosis in β cells. Next, we verified that ethanol treatment induced increases in ER Ca2+ store and apoptosis in pancreatic β cells, whereas adenovirus-mediated KCNH6 overexpression in islets attenuated ethanol-induced ER stress and apoptosis. In addition, tail-vein injections of KCNH6 lentivirus rescued KCNH6 expression in βKO mice, restored ER Ca2+ overload and attenuated ER stress in β cells, which further confirms that KCNH6 protects islets from ER stress and apoptosis. These data suggest that KCNH6 on the ER membrane may help to stabilize intracellular ER Ca2+ stores and protect β cells from ER stress and apoptosis. In conclusion, our study reveals the protective potential of KCNH6-targeting drugs in ER stress-induced diabetes.
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Affiliation(s)
- Feng-Ran Xiong
- Department of Endocrinology, Beijing Diabetes Institute, Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Laboratory for Clinical Medicine, Capital Medical University, Beijing, China
| | - Jing Lu
- Department of Endocrinology, Beijing Diabetes Institute, Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Laboratory for Clinical Medicine, Capital Medical University, Beijing, China
| | - Juan-Juan Zhu
- Department of Endocrinology, Beijing Diabetes Institute, Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Laboratory for Clinical Medicine, Capital Medical University, Beijing, China
| | - Ru-Xuan Zhao
- Department of Endocrinology, Beijing Diabetes Institute, Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Laboratory for Clinical Medicine, Capital Medical University, Beijing, China
| | - Ying-Chao Zhang
- Department of Endocrinology, Beijing Diabetes Institute, Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Laboratory for Clinical Medicine, Capital Medical University, Beijing, China
| | - Jin-Kui Yang
- Department of Endocrinology, Beijing Diabetes Institute, Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Laboratory for Clinical Medicine, Capital Medical University, Beijing, China
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Ichimura A, Miyazaki Y, Nagatomo H, Kawabe T, Nakajima N, Kim GE, Tomizawa M, Okamoto N, Komazaki S, Kakizawa S, Nishi M, Takeshima H. Atypical cell death and insufficient matrix organization in long-bone growth plates from Tric-b-knockout mice. Cell Death Dis 2023; 14:848. [PMID: 38123563 PMCID: PMC10733378 DOI: 10.1038/s41419-023-06285-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 10/27/2023] [Accepted: 11/07/2023] [Indexed: 12/23/2023]
Abstract
TRIC-A and TRIC-B proteins form homotrimeric cation-permeable channels in the endoplasmic reticulum (ER) and nuclear membranes and are thought to contribute to counterionic flux coupled with store Ca2+ release in various cell types. Serious mutations in the TRIC-B (also referred to as TMEM38B) locus cause autosomal recessive osteogenesis imperfecta (OI), which is characterized by insufficient bone mineralization. We have reported that Tric-b-knockout mice can be used as an OI model; Tric-b deficiency deranges ER Ca2+ handling and thus reduces extracellular matrix (ECM) synthesis in osteoblasts, leading to poor mineralization. Here we report irregular cell death and insufficient ECM in long-bone growth plates from Tric-b-knockout embryos. In the knockout growth plate chondrocytes, excess pro-collagen fibers were occasionally accumulated in severely dilated ER elements. Of the major ER stress pathways, activated PERK/eIF2α (PKR-like ER kinase/ eukaryotic initiation factor 2α) signaling seemed to inordinately alter gene expression to induce apoptosis-related proteins including CHOP (CCAAT/enhancer binding protein homologous protein) and caspase 12 in the knockout chondrocytes. Ca2+ imaging detected aberrant Ca2+ handling in the knockout chondrocytes; ER Ca2+ release was impaired, while cytoplasmic Ca2+ level was elevated. Our observations suggest that Tric-b deficiency directs growth plate chondrocytes to pro-apoptotic states by compromising cellular Ca2+-handling and exacerbating ER stress response, leading to impaired ECM synthesis and accidental cell death.
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Affiliation(s)
- Atsuhiko Ichimura
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Yuu Miyazaki
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Hiroki Nagatomo
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Takaaki Kawabe
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Nobuhisa Nakajima
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Ga Eun Kim
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Masato Tomizawa
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Naoki Okamoto
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | | | - Sho Kakizawa
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Miyuki Nishi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Hiroshi Takeshima
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan.
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Yu H, Li C, Wu H, Xia W, Wang Y, Zhao J, Xu C. Pathogenic mechanisms of osteogenesis imperfecta, evidence for classification. Orphanet J Rare Dis 2023; 18:234. [PMID: 37559063 PMCID: PMC10411007 DOI: 10.1186/s13023-023-02849-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 07/31/2023] [Indexed: 08/11/2023] Open
Abstract
Osteogenesis imperfecta (OI) is a connective tissue disorder affecting the skeleton and other organs, which has multiple genetic patterns, numerous causative genes, and complex pathogenic mechanisms. The previous classifications lack structure and scientific basis and have poor applicability. In this paper, we summarize and sort out the pathogenic mechanisms of OI, and analyze the molecular pathogenic mechanisms of OI from the perspectives of type I collagen defects(synthesis defects, processing defects, post-translational modification defects, folding and cross-linking defects), bone mineralization disorders, osteoblast differentiation and functional defects respectively, and also generalize several new untyped OI-causing genes and their pathogenic mechanisms, intending to provide the evidence of classification and a scientific basis for the precise diagnosis and treatment of OI.
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Affiliation(s)
- Hongjie Yu
- Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, China
- Shandong Institute of Endocrine and Metabolic Diseases, Jinan, Shandong, 250021, China
- Shandong Engineering Research Center of Stem Cell and Gene Therapy for Endocrine and Metabolic Diseases, Jinan, Shandong, 250021, China
| | - Changrong Li
- Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, China
- Shandong Institute of Endocrine and Metabolic Diseases, Jinan, Shandong, 250021, China
- Shandong Engineering Research Center of Stem Cell and Gene Therapy for Endocrine and Metabolic Diseases, Jinan, Shandong, 250021, China
| | - Huixiao Wu
- Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, China
- Shandong Institute of Endocrine and Metabolic Diseases, Jinan, Shandong, 250021, China
- Shandong Engineering Research Center of Stem Cell and Gene Therapy for Endocrine and Metabolic Diseases, Jinan, Shandong, 250021, China
| | - Weibo Xia
- Department of Endocrinology, Key Laboratory of Endocrinology, Peking Union Medical College Hospital, National Commission of Health, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 100730
| | - Yanzhou Wang
- Department of Pediatric Orthopedics, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, China
| | - Jiajun Zhao
- Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, China
- Shandong Institute of Endocrine and Metabolic Diseases, Jinan, Shandong, 250021, China
- Shandong Engineering Research Center of Stem Cell and Gene Therapy for Endocrine and Metabolic Diseases, Jinan, Shandong, 250021, China
| | - Chao Xu
- Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, China.
- Shandong Institute of Endocrine and Metabolic Diseases, Jinan, Shandong, 250021, China.
- Shandong Engineering Research Center of Stem Cell and Gene Therapy for Endocrine and Metabolic Diseases, Jinan, Shandong, 250021, China.
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Besio R, Contento BM, Garibaldi N, Filibian M, Sonntag S, Shmerling D, Tonelli F, Biggiogera M, Brini M, Salmaso A, Jovanovic M, Marini JC, Rossi A, Forlino A. CaMKII inhibition due to TRIC-B loss-of-function dysregulates SMAD signaling in osteogenesis imperfecta. Matrix Biol 2023; 120:43-59. [PMID: 37178987 PMCID: PMC11123566 DOI: 10.1016/j.matbio.2023.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 05/02/2023] [Accepted: 05/10/2023] [Indexed: 05/15/2023]
Abstract
Ca2+ is a second messenger that regulates a variety of cellular responses in bone, including osteoblast differentiation. Mutations in trimeric intracellular cation channel B (TRIC-B), an endoplasmic reticulum channel specific for K+, a counter ion for Ca2+flux, affect bone and cause a recessive form of osteogenesis imperfecta (OI) with a still puzzling mechanism. Using a conditional Tmem38b knock out mouse, we demonstrated that lack of TRIC-B in osteoblasts strongly impairs skeleton growth and structure, leading to bone fractures. At the cellular level, delayed osteoblast differentiation and decreased collagen synthesis were found consequent to the Ca2+ imbalance and associated with reduced collagen incorporation in the extracellular matrix and poor mineralization. The impaired SMAD signaling detected in mutant mice, and validated in OI patient osteoblasts, explained the osteoblast malfunction. The reduced SMAD phosphorylation and nuclear translocation were mainly caused by alteration in Ca2+ calmodulin kinase II (CaMKII)-mediated signaling and to a less extend by a lower TGF-β reservoir. SMAD signaling, osteoblast differentiation and matrix mineralization were only partially rescued by TGF-β treatment, strengthening the impact of CaMKII-SMAD axes on osteoblast function. Our data established the TRIC-B role in osteoblasts and deepened the contribution of the CaMKII-SMAD signaling in bone.
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Affiliation(s)
- Roberta Besio
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Barbara M Contento
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Nadia Garibaldi
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Marta Filibian
- Centro Grandi Strumenti, University of Pavia, Pavia, Italy; INFN, Istituto Nazionale di Fisica Nucleare-Pavia Unit, Pavia, Italy
| | - Stephan Sonntag
- PolyGene AG, Rümlang, Switzerland; LIMES-Institute, University of Bonn, Bonn , Germany
| | | | - Francesca Tonelli
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Marco Biggiogera
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Marisa Brini
- Department of Biology, University of Padova, Padova, Italy; Centro Studi per la Neurodegenerazione (CESNE), University of Padova, Padova, Italy
| | - Andrea Salmaso
- Department of Biology, University of Padova, Padova, Italy
| | - Milena Jovanovic
- Section on Heritable Disorders of Bone and Extracellular Matrix, Eunice Kennedy Shiver National Institute of Child Health and Human Development, National Institute of Health, Bethesda, MD, United States of America
| | - Joan C Marini
- Section on Heritable Disorders of Bone and Extracellular Matrix, Eunice Kennedy Shiver National Institute of Child Health and Human Development, National Institute of Health, Bethesda, MD, United States of America
| | - Antonio Rossi
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Antonella Forlino
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy.
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Tonelli F, Leoni L, Daponte V, Gioia R, Cotti S, Fiedler IAK, Larianova D, Willaert A, Coucke PJ, Villani S, Busse B, Besio R, Rossi A, Witten PE, Forlino A. Zebrafish Tric-b is required for skeletal development and bone cells differentiation. Front Endocrinol (Lausanne) 2023; 14:1002914. [PMID: 36755921 PMCID: PMC9899828 DOI: 10.3389/fendo.2023.1002914] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 01/03/2023] [Indexed: 01/24/2023] Open
Abstract
INTRODUCTION Trimeric intracellular potassium channels TRIC-A and -B are endoplasmic reticulum (ER) integral membrane proteins, involved in the regulation of calcium release mediated by ryanodine (RyRs) and inositol 1,4,5-trisphosphate (IP3Rs) receptors, respectively. While TRIC-A is mainly expressed in excitable cells, TRIC-B is ubiquitously distributed at moderate level. TRIC-B deficiency causes a dysregulation of calcium flux from the ER, which impacts on multiple collagen specific chaperones and modifying enzymatic activity, leading to a rare form of osteogenesis imperfecta (OI Type XIV). The relevance of TRIC-B on cell homeostasis and the molecular mechanism behind the disease are still unknown. RESULTS In this study, we exploited zebrafish to elucidate the role of TRIC-B in skeletal tissue. We demonstrated, for the first time, that tmem38a and tmem38b genes encoding Tric-a and -b, respectively are expressed at early developmental stages in zebrafish, but only the latter has a maternal expression. Two zebrafish mutants for tmem38b were generated by CRISPR/Cas9, one carrying an out of frame mutation introducing a premature stop codon (tmem38b-/- ) and one with an in frame deletion that removes the highly conserved KEV domain (tmem38bΔ120-7/Δ120-7 ). In both models collagen type I is under-modified and partially intracellularly retained in the endoplasmic reticulum, as described in individuals affected by OI type XIV. Tmem38b-/- showed a mild skeletal phenotype at the late larval and juvenile stages of development whereas tmem38bΔ120-7/Δ120-7 bone outcome was limited to a reduced vertebral length at 21 dpf. A caudal fin regeneration study pointed towards impaired activity of osteoblasts and osteoclasts associated with mineralization impairment. DISCUSSION Our data support the requirement of Tric-b during early development and for bone cell differentiation.
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Affiliation(s)
- Francesca Tonelli
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Laura Leoni
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Valentina Daponte
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Roberta Gioia
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Silvia Cotti
- Department of Biology, Ghent University, Ghent, Belgium
| | - Imke A. K. Fiedler
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Andy Willaert
- Department of Biomolecular Medicine, Center of Medical Genetics, Ghent University-University Hospital, Ghent, Belgium
| | - Paul J. Coucke
- Department of Biomolecular Medicine, Center of Medical Genetics, Ghent University-University Hospital, Ghent, Belgium
| | - Simona Villani
- Department of Public Health and Experimental and Forensic Medicine, Unit of Biostatistics and Clinical Epidemiology, University of Pavia, Pavia, Italy
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Roberta Besio
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Antonio Rossi
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | | | - Antonella Forlino
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
- *Correspondence: Antonella Forlino,
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Lv F, Cai X, Ji L. An Update on Animal Models of Osteogenesis Imperfecta. Calcif Tissue Int 2022; 111:345-366. [PMID: 35767009 DOI: 10.1007/s00223-022-00998-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 06/01/2022] [Indexed: 11/02/2022]
Abstract
Osteogenesis imperfecta (OI) is a heterogeneous disorder characterized by bone fragility, multiple fractures, bone deformity, and short stature. In recent years, the application of next generation sequencing has triggered the discovery of many new genetic causes for OI. Until now, more than 25 genetic causes of OI and closely related disorders have been identified. However, the mechanisms of many genes on skeletal fragility in OI are not entirely clear. Animal models of OI could help to understand the cellular, signaling, and metabolic mechanisms contributing to the disease, and how targeting these pathways can provide therapeutic targets. To date, a lot of animal models, mainly mice and zebrafish, have been described with defects in 19 OI-associated genes. In this review, we summarize the known genetic causes and animal models that recapitulate OI with a main focus on engineered mouse and zebrafish models. Additionally, we briefly discuss domestic animals with naturally occurring OI phenotypes. Knowledge of the specific molecular basis of OI will advance clinical diagnosis and potentially stimulate targeted therapeutic approaches.
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Affiliation(s)
- Fang Lv
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Xizhimen South Street No.11, Beijing, 100044, China
| | - Xiaoling Cai
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Xizhimen South Street No.11, Beijing, 100044, China.
| | - Linong Ji
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Xizhimen South Street No.11, Beijing, 100044, China.
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Padhy B, Xie J, Wang R, Lin F, Huang CL. Channel Function of Polycystin-2 in the Endoplasmic Reticulum Protects against Autosomal Dominant Polycystic Kidney Disease. J Am Soc Nephrol 2022; 33:1501-1516. [PMID: 35835458 PMCID: PMC9342640 DOI: 10.1681/asn.2022010053] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 04/03/2022] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Mutations of PKD2, which encodes polycystin-2, cause autosomal dominant polycystic kidney disease (ADPKD). The prevailing view is that defects in polycystin-2-mediated calcium ion influx in the primary cilia play a central role in the pathogenesis of cyst growth. However, polycystin-2 is predominantly expressed in the endoplasmic reticulum (ER) and more permeable to potassium ions than to calcium ions. METHODS The trimeric intracellular cation (TRIC) channel TRIC-B is an ER-resident potassium channel that mediates potassium-calcium counterion exchange for inositol trisphosphate-mediated calcium ion release. Using TRIC-B as a tool, we examined the function of ER-localized polycystin-2 and its role in ADPKD pathogenesis in cultured cells, zebrafish, and mouse models. RESULTS Agonist-induced ER calcium ion release was defective in cells lacking polycystin-2 and reversed by exogenous expression of TRIC-B. Vice versa, exogenous polycystin-2 reversed an ER calcium-release defect in cells lacking TRIC-B. In a zebrafish model, expression of wild-type but not nonfunctional TRIC-B suppressed polycystin-2-deficient phenotypes. Similarly, these phenotypes were suppressed by targeting the ROMK potassium channel (normally expressed on the cell surface) to the ER. In cultured cells and polycystin-2-deficient zebrafish phenotypes, polycystin-2 remained capable of reversing the ER calcium release defect even when it was not present in the cilia. Transgenic expression of Tric-b ameliorated cystogenesis in the kidneys of conditional Pkd2-inactivated mice, whereas Tric-b deletion enhanced cystogenesis in Pkd2-heterozygous kidneys. CONCLUSIONS Polycystin-2 in the ER appears to be critical for anticystogenesis and likely functions as a potassium ion channel to facilitate potassium-calcium counterion exchange for inositol trisphosphate-mediated calcium release. The results advance the understanding of ADPKD pathogenesis and provides proof of principle for pharmacotherapy by TRIC-B activators.
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Affiliation(s)
- Biswajit Padhy
- Division of Nephrology, Department of Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Jian Xie
- Division of Nephrology, Department of Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Runping Wang
- Division of Nephrology, Department of Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Fang Lin
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Chou-Long Huang
- Division of Nephrology, Department of Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
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Zhang N, Pan H, Liang X, Xie J, Han W. The roles of transmembrane family proteins in the regulation of store-operated Ca 2+ entry. Cell Mol Life Sci 2022; 79:118. [PMID: 35119538 PMCID: PMC11071953 DOI: 10.1007/s00018-021-04034-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 12/15/2022]
Abstract
Store-operated Ca2+ entry (SOCE) is a major pathway for calcium signaling, which regulates almost every biological process, involving cell proliferation, differentiation, movement and death. Stromal interaction molecule (STIM) and ORAI calcium release-activated calcium modulator (ORAI) are the two major proteins involved in SOCE. With the deepening of studies, more and more proteins are found to be able to regulate SOCE, among which the transmembrane (TMEM) family proteins are worth paying more attention. In addition, the ORAI proteins belong to the TMEM family themselves. As the name suggests, TMEM family is a type of proteins that spans biological membranes including plasma membrane and membrane of organelles. TMEM proteins are in a large family with more than 300 proteins that have been already identified, while the functional knowledge about the proteins is preliminary. In this review, we mainly summarized the TMEM proteins that are involved in SOCE, to better describe a picture of the interaction between STIM and ORAI proteins during SOCE and its downstream signaling pathways, as well as to provide an idea for the study of the TMEM family proteins.
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Affiliation(s)
- Ningxia Zhang
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Hongming Pan
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Xiaojing Liang
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Jiansheng Xie
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
- Laboratory of Cancer Biology, Institute of Clinical Science, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
| | - Weidong Han
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
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11
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Jovanovic M, Guterman-Ram G, Marini JC. Osteogenesis Imperfecta: Mechanisms and Signaling Pathways Connecting Classical and Rare OI Types. Endocr Rev 2022; 43:61-90. [PMID: 34007986 PMCID: PMC8755987 DOI: 10.1210/endrev/bnab017] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Osteogenesis imperfecta (OI) is a phenotypically and genetically heterogeneous skeletal dysplasia characterized by bone fragility, growth deficiency, and skeletal deformity. Previously known to be caused by defects in type I collagen, the major protein of extracellular matrix, it is now also understood to be a collagen-related disorder caused by defects in collagen folding, posttranslational modification and processing, bone mineralization, and osteoblast differentiation, with inheritance of OI types spanning autosomal dominant and recessive as well as X-linked recessive. This review provides the latest updates on OI, encompassing both classical OI and rare forms, their mechanism, and the signaling pathways involved in their pathophysiology. There is a special emphasis on mutations in type I procollagen C-propeptide structure and processing, the later causing OI with strikingly high bone mass. Types V and VI OI, while notably different, are shown to be interrelated by the interferon-induced transmembrane protein 5 p.S40L mutation that reveals the connection between the bone-restricted interferon-induced transmembrane protein-like protein and pigment epithelium-derived factor pathways. The function of regulated intramembrane proteolysis has been extended beyond cholesterol metabolism to bone formation by defects in regulated membrane proteolysis components site-2 protease and old astrocyte specifically induced-substance. Several recently proposed candidate genes for new types of OI are also presented. Discoveries of new OI genes add complexity to already-challenging OI management; current and potential approaches are summarized.
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Affiliation(s)
- Milena Jovanovic
- Section on Heritable Disorders of Bone and Extracellular Matrix, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Gali Guterman-Ram
- Section on Heritable Disorders of Bone and Extracellular Matrix, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Joan C Marini
- Section on Heritable Disorders of Bone and Extracellular Matrix, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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12
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Knocking out TMEM38B in human foetal osteoblasts hFOB 1.19 by CRISPR/Cas9: A model for recessive OI type XIV. PLoS One 2021; 16:e0257254. [PMID: 34582479 PMCID: PMC8478202 DOI: 10.1371/journal.pone.0257254] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 08/26/2021] [Indexed: 11/19/2022] Open
Abstract
Osteogenesis imperfecta (OI) type XIV is a rare recessive bone disorder characterized by variable degree of severity associated to osteopenia. It is caused by mutations in TMEM38B encoding for the trimeric intracellular cation channel TRIC-B, specific for potassium and ubiquitously present in the endoplasmic reticulum (ER) membrane. OI type XIV molecular basis is largely unknown and, due to the rarity of the disease, the availability of patients’ osteoblasts is challenging. Thus, CRISPR/Cas9 was used to knock out (KO) TMEM38B in the human Foetal Osteoblast hFOB 1.19 to obtain an OI type XIV model. CRISPR/Cas9 is a powerful technology to generate in vitro and in vivo models for heritable disorders. Its limited cost and ease of use make this technique widely applicable in most laboratories. Nevertheless, to fully take advantage of this approach, it is important to be aware of its strengths and limitations. Three gRNAs were used and several KO clones lacking the expression of TRIC-B were obtained. Few clones were validated as good models for the disease since they reproduce the altered ER calcium flux, collagen I structure and impaired secretion and osteoblastic markers expression detected in patients’ cells. Impaired proliferation and mineralization in KO clones unveiled the relevance of TRIC-B in osteoblasts functionality.
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13
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Ramzan K, Alotaibi M, Huma R, Afzal S. Detection of a Recurrent TMEM38B Gene Deletion Associated with Recessive Osteogenesis Imperfecta. Discoveries (Craiova) 2021; 9:e124. [PMID: 34036147 PMCID: PMC8140756 DOI: 10.15190/d.2021.3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Osteogenesis imperfecta is a clinically and genetically group of heterogeneous disorders associated with decreased bone density, brittle bones, bone deformity, recurrent fractures, and growth retardation. Osteogenesis imperfecta is commonly associated with mutations of the genes encoding for type I collagen (COL1A1/COL1A2). Mutations in other genes, some associated with type I collagen post-translational processing, have also been identified as the cause of osteogenesis imperfecta. Mutations in the transmembrane protein 38B (TMEM38B) gene have been reported in a rare autosomal recessive form of osteogenesis imperfecta. TMEM38B encodes TRIC-B - a trimeric intracellular cation channel type B which is essential to modulate intracellular calcium signaling. In this study, we are reporting a case of osteogenesis imperfecta type XIV from a Saudi consanguineous family. Our patient was an eight-month-old child with short limbs, club feet, and lower limb deformities with developmental delay. Radiological findings were consistent with the evidence of osteogenesis imperfecta. There was no evidence of impaired hearing or blue sclera and based on the clinical assessment, we classified our patient as a non-syndromic osteogenesis imperfecta. A pathogenic deletion in the chromosome 9q31.2 region, partially encompassing the TMEM38B gene, was detected using chromosomal microarray analysis. This study expands our knowledge about the rare type of osteogenesis imperfecta in our consanguineous population. Besides, it emphasizes the use of genomic medicine in clinical practices to formulate early interventions to clinically improve the patient’s condition.
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Affiliation(s)
- Khushnooda Ramzan
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Maha Alotaibi
- Department of Genetics, Children's Hospital, King Saud Medical City, Riyadh, Saudi Arabia
| | - Rozeena Huma
- King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Sibtain Afzal
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
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14
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Zhou X, Li A, Lin PH, Zhou J, Ma J. TRIC-A regulates intracellular Ca 2+ homeostasis in cardiomyocytes. Pflugers Arch 2021; 473:547-556. [PMID: 33474637 PMCID: PMC7940156 DOI: 10.1007/s00424-021-02513-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/14/2020] [Accepted: 01/04/2021] [Indexed: 01/26/2023]
Abstract
Trimeric intracellular cation (TRIC) channels have been identified as monovalent cation channels that are located in the ER/SR membrane. Two isoforms discovered in mammals are TRIC-A (TMEM38a) and TRIC-B (TMEM38b). TRIC-B ubiquitously expresses in all tissues, and TRIC-B-/- mice is lethal at the neonatal stage. TRIC-A mainly expresses in excitable cells. TRIC-A-/- mice survive normally but show abnormal SR Ca2+ handling in both skeletal and cardiac muscle cells. Importantly, TRIC-A mutations have been identified in human patients with stress-induced arrhythmia. In the past decade, important discoveries have been made to understand the structure and function of TRIC channels, especially its role in regulating intracellular Ca2+ homeostasis. In this review article, we focus on the potential roles of TRIC-A in regulating cardiac function, particularly its effects on intracellular Ca2+ signaling of cardiomyocytes and discuss the current knowledge gaps.
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Affiliation(s)
- Xinyu Zhou
- Department of Surgery, The Ohio State University Columbus, Columbus, OH, 43210, USA
| | - Ang Li
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, 76019, USA
| | - Pei-Hui Lin
- Department of Surgery, The Ohio State University Columbus, Columbus, OH, 43210, USA
| | - Jingsong Zhou
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, 76019, USA
| | - Jianjie Ma
- Department of Surgery, The Ohio State University Columbus, Columbus, OH, 43210, USA.
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15
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He F, Yu J, Yang J, Wang S, Zhuang A, Shi H, Gu X, Xu X, Chai P, Jia R. m 6A RNA hypermethylation-induced BACE2 boosts intracellular calcium release and accelerates tumorigenesis of ocular melanoma. Mol Ther 2021; 29:2121-2133. [PMID: 33601055 DOI: 10.1016/j.ymthe.2021.02.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/22/2021] [Accepted: 02/10/2021] [Indexed: 12/11/2022] Open
Abstract
Ocular melanoma, including uveal melanoma (UM) and conjunctival melanoma (CM), is the most common and deadly eye cancer in adults. Both UM and CM originate from melanocytes and exhibit an aggressive growth pattern with high rates of metastasis and mortality. The integral membrane glycoprotein beta-secretase 2 (BACE2), an enzyme that cleaves amyloid precursor protein into amyloid beta peptide, has been reported to play a vital role in vertebrate pigmentation and metastatic melanoma. However, the role of BACE2 in ocular melanoma remains unclear. In this study, we showed that BACE2 was significantly upregulated in ocular melanoma, and inhibition of BACE2 significantly impaired tumor progression both in vitro and in vivo. Notably, we identified that transmembrane protein 38B (TMEM38B), whose expression was highly dependent on BACE2, modulated calcium release from endoplasmic reticulum (ER). Inhibition of the BACE2/TMEM38B axis could trigger exhaustion of intracellular calcium release and inhibit tumor progression. We further demonstrated that BACE2 presented an increased level of N6-methyladenosine (m6A) RNA methylation, which led to the upregulation of BACE2 mRNA. To our knowledge, this study provides a novel pattern of BACE2-mediated intracellular calcium release in ocular melanoma progression, and our findings suggest that m6A/BACE2/TMEM38b could be a potential therapeutic axis for ocular melanoma.
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Affiliation(s)
- Fanglin He
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200001, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai 200001, China
| | - Jie Yu
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200001, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai 200001, China
| | - Jie Yang
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200001, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai 200001, China
| | - Shaoyun Wang
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200001, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai 200001, China
| | - Ai Zhuang
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200001, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai 200001, China
| | - Hanhan Shi
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200001, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai 200001, China
| | - Xiang Gu
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200001, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai 200001, China
| | - Xiaofang Xu
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200001, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai 200001, China
| | - Peiwei Chai
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200001, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai 200001, China
| | - Renbing Jia
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200001, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai 200001, China.
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16
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Njegic A, Wilson C, Cartwright EJ. Targeting Ca 2 + Handling Proteins for the Treatment of Heart Failure and Arrhythmias. Front Physiol 2020; 11:1068. [PMID: 33013458 PMCID: PMC7498719 DOI: 10.3389/fphys.2020.01068] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/04/2020] [Indexed: 12/18/2022] Open
Abstract
Diseases of the heart, such as heart failure and cardiac arrhythmias, are a growing socio-economic burden. Calcium (Ca2+) dysregulation is key hallmark of the failing myocardium and has long been touted as a potential therapeutic target in the treatment of a variety of cardiovascular diseases (CVD). In the heart, Ca2+ is essential for maintaining normal cardiac function through the generation of the cardiac action potential and its involvement in excitation contraction coupling. As such, the proteins which regulate Ca2+ cycling and signaling play a vital role in maintaining Ca2+ homeostasis. Changes to the expression levels and function of Ca2+-channels, pumps and associated intracellular handling proteins contribute to altered Ca2+ homeostasis in CVD. The remodeling of Ca2+-handling proteins therefore results in impaired Ca2+ cycling, Ca2+ leak from the sarcoplasmic reticulum and reduced Ca2+ clearance, all of which contributes to increased intracellular Ca2+. Currently, approved treatments for targeting Ca2+ handling dysfunction in CVD are focused on Ca2+ channel blockers. However, whilst Ca2+ channel blockers have been successful in the treatment of some arrhythmic disorders, they are not universally prescribed to heart failure patients owing to their ability to depress cardiac function. Despite the progress in CVD treatments, there remains a clear need for novel therapeutic approaches which are able to reverse pathophysiology associated with heart failure and arrhythmias. Given that heart failure and cardiac arrhythmias are closely associated with altered Ca2+ homeostasis, this review will address the molecular changes to proteins associated with both Ca2+-handling and -signaling; their potential as novel therapeutic targets will be discussed in the context of pre-clinical and, where available, clinical data.
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Affiliation(s)
- Alexandra Njegic
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom.,Centre for Tumour Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Claire Wilson
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom.,Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Elizabeth J Cartwright
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom
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17
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Zhou X, Park KH, Yamazaki D, Lin PH, Nishi M, Ma Z, Qiu L, Murayama T, Zou X, Takeshima H, Zhou J, Ma J. TRIC-A Channel Maintains Store Calcium Handling by Interacting With Type 2 Ryanodine Receptor in Cardiac Muscle. Circ Res 2019; 126:417-435. [PMID: 31805819 DOI: 10.1161/circresaha.119.316241] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
RATIONALE Trimeric intracellular cation (TRIC)-A and B are distributed to endoplasmic reticulum/sarcoplasmic reticulum intracellular Ca2+ stores. The crystal structure of TRIC has been determined, confirming the homotrimeric structure of a potassium channel. While the pore architectures of TRIC-A and TRIC-B are conserved, the carboxyl-terminal tail (CTT) domains of TRIC-A and TRIC-B are different from each other. Aside from its recognized role as a counterion channel that participates in excitation-contraction coupling of striated muscles, the physiological function of TRIC-A in heart physiology and disease has remained largely unexplored. OBJECTIVE In cardiomyocytes, spontaneous Ca2+ waves, triggered by store overload-induced Ca2+ release mediated by the RyR2 (type 2 ryanodine receptor), develop extrasystolic contractions often associated with arrhythmic events. Here, we test the hypothesis that TRIC-A is a physiological component of RyR2-mediated Ca2+ release machinery that directly modulates store overload-induced Ca2+ release activity via CTT. METHODS AND RESULTS We show that cardiomyocytes derived from the TRIC-A-/- (TRIC-A knockout) mice display dysregulated Ca2+ movement across sarcoplasmic reticulum. Biochemical studies demonstrate a direct interaction between CTT-A and RyR2. Modeling and docking studies reveal potential sites on RyR2 that show differential interactions with CTT-A and CTT-B. In HEK293 (human embryonic kidney) cells with stable expression of RyR2, transient expression of TRIC-A, but not TRIC-B, leads to apparent suppression of spontaneous Ca2+ oscillations. Ca2+ measurements using the cytosolic indicator Fura-2 and the endoplasmic reticulum luminal store indicator D1ER suggest that TRIC-A enhances Ca2+ leak across the endoplasmic reticulum by directly targeting RyR2 to modulate store overload-induced Ca2+ release. Moreover, synthetic CTT-A peptide facilitates RyR2 activity in lipid bilayer reconstitution system, enhances Ca2+ sparks in permeabilized TRIC-A-/- cardiomyocytes, and induces intracellular Ca2+ release after microinjection into isolated cardiomyocytes, whereas such effects were not observed with the CTT-B peptide. In response to isoproterenol stimulation, the TRIC-A-/- mice display irregular ECG and develop more fibrosis than the WT (wild type) littermates. CONCLUSIONS In addition to the ion-conducting function, TRIC-A functions as an accessory protein of RyR2 to modulate sarcoplasmic reticulum Ca2+ handling in cardiac muscle.
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Affiliation(s)
- Xinyu Zhou
- From the Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus (X. Zhou, K.H.P., P.-h.L., J.M.)
| | - Ki Ho Park
- From the Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus (X. Zhou, K.H.P., P.-h.L., J.M.)
| | - Daiju Yamazaki
- Department of Biological Chemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Japan (D.Y., M.N., H.T.)
| | - Pei-Hui Lin
- From the Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus (X. Zhou, K.H.P., P.-h.L., J.M.)
| | - Miyuki Nishi
- Department of Biological Chemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Japan (D.Y., M.N., H.T.)
| | - Zhiwei Ma
- Department of Physics and Astronomy, Dalton Cardiovascular Research Center (Z.M., L.Q., X. Zou), University of Missouri, Columbia.,Department of Biochemistry (Z.M., L.Q., X. Zou), University of Missouri, Columbia
| | - Liming Qiu
- Department of Physics and Astronomy, Dalton Cardiovascular Research Center (Z.M., L.Q., X. Zou), University of Missouri, Columbia.,Department of Biochemistry (Z.M., L.Q., X. Zou), University of Missouri, Columbia
| | - Takashi Murayama
- Department of Pharmacology, Juntendo University School of Medicine, Tokyo, Japan (T.M.)
| | - Xiaoqin Zou
- Department of Physics and Astronomy, Dalton Cardiovascular Research Center (Z.M., L.Q., X. Zou), University of Missouri, Columbia.,Department of Biochemistry (Z.M., L.Q., X. Zou), University of Missouri, Columbia
| | - Hiroshi Takeshima
- Department of Biological Chemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Japan (D.Y., M.N., H.T.)
| | - Jingsong Zhou
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington (J.Z.)
| | - Jianjie Ma
- From the Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus (X. Zhou, K.H.P., P.-h.L., J.M.)
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18
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O'Brien F, Eberhardt D, Witschas K, El‐Ajouz S, Iida T, Nishi M, Takeshima H, Sitsapesan R, Venturi E. Enhanced activity of multiple TRIC-B channels: an endoplasmic reticulum/sarcoplasmic reticulum mechanism to boost counterion currents. J Physiol 2019; 597:2691-2705. [PMID: 30907436 PMCID: PMC6567852 DOI: 10.1113/jp277241] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 03/20/2019] [Indexed: 01/27/2023] Open
Abstract
KEY POINTS There are two subtypes of trimeric intracellular cation (TRIC) channels but their distinct single-channel properties and physiological regulation have not been characterized. We examined the differences in function between native skeletal muscle sarcoplasmic reticulum (SR) K+ -channels from wild-type (WT) mice (where TRIC-A is the principal subtype) and from Tric-a knockout (KO) mice that only express TRIC-B. We find that lone SR K+ -channels from Tric-a KO mice have a lower open probability and gate more frequently in subconducting states than channels from WT mice but, unlike channels from WT mice, multiple channels gate with high open probability with a more than six-fold increase in activity when four channels are present in the bilayer. No evidence was found for a direct gating interaction between ryanodine receptor and SR K+ -channels in Tric-a KO SR, suggesting that TRIC-B-TRIC-B interactions are highly specific and may be important for meeting counterion requirements during excitation-contraction coupling in tissues where TRIC-A is sparse or absent. ABSTRACT The trimeric intracellular cation channels, TRIC-A and TRIC-B, represent two subtypes of sarcoplasmic reticulum (SR) K+ -channel but their individual functional roles are unknown. We therefore compared the biophysical properties of SR K+ -channels derived from the skeletal muscle of wild-type (WT) or Tric-a knockout (KO) mice. Because TRIC-A is the major TRIC-subtype in skeletal muscle, WT SR will predominantly contain TRIC-A channels, whereas Tric-a KO SR will only contain TRIC-B channels. When lone SR K+ -channels were incorporated into bilayers, the open probability (Po) of channels from Tric-a KO mice was markedly lower than that of channels from WT mice; gating was characterized by shorter opening bursts and more frequent brief subconductance openings. However, unlike channels from WT mice, the Po of SR K+ -channels from Tric-a KO mice increased as increasing channel numbers were present in the bilayer, driving the channels into long sojourns in the fully open state. When co-incorporated into bilayers, ryanodine receptor channels did not directly affect the gating of SR K+ -channels, nor did the presence or absence of SR K+ -channels influence ryanodine receptor activity. We suggest that because of high expression levels in striated muscle, TRIC-A produces most of the counterion flux required during excitation-contraction coupling. TRIC-B, in contrast, is sparsely expressed in most cells and, although lone TRIC-B channels exhibit low Po, the high Po levels reached by multiple TRIC-B channels may provide a compensatory mechanism to rapidly restore K+ gradients and charge differences across the SR of tissues containing few TRIC-A channels.
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Affiliation(s)
- Fiona O'Brien
- Department of PharmacologyUniversity of OxfordOxfordUK
| | | | | | - Sam El‐Ajouz
- Department of PharmacologyUniversity of OxfordOxfordUK
| | - Tsunaki Iida
- Graduate School of Pharmaceutical SciencesKyoto UniversityKyotoJapan
| | - Miyuki Nishi
- Graduate School of Pharmaceutical SciencesKyoto UniversityKyotoJapan
| | - Hiroshi Takeshima
- Graduate School of Pharmaceutical SciencesKyoto UniversityKyotoJapan
| | | | - Elisa Venturi
- Department of PharmacologyUniversity of OxfordOxfordUK
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19
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Cao YJ, Zhang H, Zhang ZL. NOVEL MUTATIONS IN THE WNT1, TMEM38B, P4HB, AND PLS3 GENES IN FOUR UNRELATED CHINESE FAMILIES WITH OSTEOGENESIS IMPERFECTA. Endocr Pract 2019; 25:230-241. [PMID: 30913006 DOI: 10.4158/ep-2018-0443] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE Osteogenesis imperfecta (OI) is a group of heritable fragile bone diseases, and the majority are caused by pathogenic variants in the COL1A1 and COL1A2 genes. We sought to identify the genetic causes and phenotypes of OI in Chinese patients without COL1A1 or COL1A2 mutations. METHODS Twenty-three patients who were diagnosed with sporadic OI but did not carry COL1A1/2 mutations were recruited, and their genomic DNA was analyzed using targeted next-generation sequencing of rare OI-related genes. The resulting damaging mutations in the probands and their parents were verified using Sanger sequencing. Moreover, the efficacy of long-term bisphosphonate treatment was evaluated in proband 1. RESULTS Compound heterozygous variants in the WNT1 and TMEM38B genes were identified in proband 1 and proband 2, respectively. A heterozygous mutation in the P4HB gene was identified in proband 3, and a hemizygous mutation in PLS3 was identified in proband 4. The unaffected parents of the probands (except the father of proband 4) with mutations in the WNT1, TMEM38B, and PLS3 genes were heterozygous carriers of each of the variants, respectively. Notably, proband 3 had the characteristic exophthalmos, flat nasal bridge and flat, wide forehead. None of the patients presented with dentinogenesis imperfecta or hearing loss. Furthermore, bisphosphonates exerted beneficial effects on proband 1, who carried the WNT1 mutations, by increasing bone mineral density Z-score, reshaping the compressed vertebrae and decreasing the fracture risk. CONCLUSION We identified novel mutations and expanded the spectrum of phenotypes and genotypes of the extremely rare disorder OI. ABBREVIATIONS BMD = bone mineral density; MIM = Mendelian Inheritance in Man; OI = osteogenesis imperfecta; PDI = protein disulfide isomerase.
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20
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Structural basis for activity of TRIC counter-ion channels in calcium release. Proc Natl Acad Sci U S A 2019; 116:4238-4243. [PMID: 30770441 DOI: 10.1073/pnas.1817271116] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Trimeric intracellular cation (TRIC) channels are thought to provide counter-ion currents that facilitate the active release of Ca2+ from intracellular stores. TRIC activity is controlled by voltage and Ca2+ modulation, but underlying mechanisms have remained unknown. Here we describe high-resolution crystal structures of vertebrate TRIC-A and TRIC-B channels, both in Ca2+-bound and Ca2+-free states, and we analyze conductance properties in structure-inspired mutagenesis experiments. The TRIC channels are symmetric trimers, wherein we find a pore in each protomer that is gated by a highly conserved lysine residue. In the resting state, Ca2+ binding at the luminal surface of TRIC-A, on its threefold axis, stabilizes lysine blockage of the pores. During active Ca2+ release, luminal Ca2+ depletion removes inhibition to permit the lysine-bearing and voltage-sensing helix to move in response to consequent membrane hyperpolarization. Diacylglycerol is found at interprotomer interfaces, suggesting a role in metabolic control.
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21
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Moon S, Im SK, Kim N, Youn H, Park UH, Kim JY, Kim AR, An SJ, Kim JH, Sun W, Hwang JT, Kim EJ, Um SJ. Asxl1 exerts an antiproliferative effect on mouse lung maturation via epigenetic repression of the E2f1-Nmyc axis. Cell Death Dis 2018; 9:1118. [PMID: 30389914 PMCID: PMC6215009 DOI: 10.1038/s41419-018-1171-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/04/2018] [Accepted: 10/19/2018] [Indexed: 11/26/2022]
Abstract
Although additional sex combs-like 1 (ASXL1) has been extensively described in hematologic malignancies, little is known about the molecular role of ASXL1 in organ development. Here, we show that Asxl1 ablation in mice results in postnatal lethality due to cyanosis, a respiratory failure. This lung defect is likely caused by higher proliferative potential and reduced expression of surfactant proteins, leading to reduced air space and defective lung maturation. By microarray analysis, we identified E2F1-responsive genes, including Nmyc, as targets repressed by Asxl1. Nmyc and Asxl1 are reciprocally expressed during the fetal development of normal mouse lungs, whereas Nmyc downregulation is impaired in Asxl1-deficient lungs. Together with E2F1 and ASXL1, host cell factor 1 (HCF-1), purified as an Asxl1-bound protein, is recruited to the E2F1-binding site of the Nmyc promoter. The interaction occurs between the C-terminal region of Asxl1 and the N-terminal Kelch domain of HCF-1. Trimethylation (me3) of histone H3 lysine 27 (H3K27) is enriched in the Nmyc promoter upon Asxl1 overexpression, whereas it is downregulated in Asxl1-deleted lung and -depleted A549 cells, similar to H3K9me3, another repressive histone marker. Overall, these findings suggest that Asxl1 modulates proliferation of lung epithelial cells via the epigenetic repression of Nmyc expression, deficiency of which may cause hyperplasia, leading to dyspnea.
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Affiliation(s)
- Seungtae Moon
- Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul, 05006, Korea
| | - Sun-Kyoung Im
- Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 06273, Korea
| | - Nackhyoung Kim
- Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul, 05006, Korea
| | - Hyesook Youn
- Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul, 05006, Korea
| | - Ui-Hyun Park
- Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul, 05006, Korea
| | - Joo-Yeon Kim
- Department of Anatomy, Korea University College of Medicine, Seoul, 02841, Korea
| | - A-Reum Kim
- Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul, 05006, Korea
| | - So-Jung An
- Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul, 05006, Korea
| | - Ji-Hoon Kim
- School of Biological Science, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea
| | - Woong Sun
- Department of Anatomy, Korea University College of Medicine, Seoul, 02841, Korea
| | - Jin-Taek Hwang
- Korea Food Research Institute, Jeonju, Jeonbuk, 55365, Korea
| | - Eun-Joo Kim
- Department of Molecular Biology, Dankook University, Chungnam, 31116, Korea
| | - Soo-Jong Um
- Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul, 05006, Korea.
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Crystal structures of the TRIC trimeric intracellular cation channel orthologues. Cell Res 2017; 26:1288-1301. [PMID: 27909292 PMCID: PMC5143425 DOI: 10.1038/cr.2016.140] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 10/23/2016] [Accepted: 10/27/2016] [Indexed: 12/30/2022] Open
Abstract
Ca2+ release from the sarcoplasmic reticulum (SR) and endoplasmic reticulum (ER) is crucial for muscle contraction, cell growth, apoptosis, learning and memory. The trimeric intracellular cation (TRIC) channels were recently identified as cation channels balancing the SR and ER membrane potentials, and are implicated in Ca2+ signaling and homeostasis. Here we present the crystal structures of prokaryotic TRIC channels in the closed state and structure-based functional analyses of prokaryotic and eukaryotic TRIC channels. Each trimer subunit consists of seven transmembrane (TM) helices with two inverted repeated regions. The electrophysiological, biochemical and biophysical analyses revealed that TRIC channels possess an ion-conducting pore within each subunit, and that the trimer formation contributes to the stability of the protein. The symmetrically related TM2 and TM5 helices are kinked at the conserved glycine clusters, and these kinks are important for the channel activity. Furthermore, the kinks of the TM2 and TM5 helices generate lateral fenestrations at each subunit interface. Unexpectedly, these lateral fenestrations are occupied with lipid molecules. This study provides the structural and functional framework for the molecular mechanism of this ion channel superfamily.
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23
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Vierra NC, Dadi PK, Milian SC, Dickerson MT, Jordan KL, Gilon P, Jacobson DA. TALK-1 channels control β cell endoplasmic reticulum Ca 2+ homeostasis. Sci Signal 2017; 10:eaan2883. [PMID: 28928238 PMCID: PMC5672804 DOI: 10.1126/scisignal.aan2883] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Ca2+ handling by the endoplasmic reticulum (ER) serves critical roles in controlling pancreatic β cell function and becomes perturbed during the pathogenesis of diabetes. ER Ca2+ homeostasis is determined by ion movements across the ER membrane, including K+ flux through K+ channels. We demonstrated that K+ flux through ER-localized TALK-1 channels facilitated Ca2+ release from the ER in mouse and human β cells. We found that β cells from mice lacking TALK-1 exhibited reduced basal cytosolic Ca2+ and increased ER Ca2+ concentrations, suggesting reduced ER Ca2+ leak. These changes in Ca2+ homeostasis were presumably due to TALK-1-mediated ER K+ flux, because we recorded K+ currents mediated by functional TALK-1 channels on the nuclear membrane, which is continuous with the ER. Moreover, overexpression of K+-impermeable TALK-1 channels in HEK293 cells did not reduce ER Ca2+ stores. Reduced ER Ca2+ content in β cells is associated with ER stress and islet dysfunction in diabetes, and islets from TALK-1-deficient mice fed a high-fat diet showed reduced signs of ER stress, suggesting that TALK-1 activity exacerbated ER stress. Our data establish TALK-1 channels as key regulators of β cell ER Ca2+ and suggest that TALK-1 may be a therapeutic target to reduce ER Ca2+ handling defects in β cells during the pathogenesis of diabetes.
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Affiliation(s)
- Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Sarah C Milian
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Kelli L Jordan
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Patrick Gilon
- Pôle d'endocrinologie, diabète et nutrition, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels 1200, Belgium
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
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Abstract
Skeletal deformity and bone fragility are the hallmarks of the brittle bone dysplasia osteogenesis imperfecta. The diagnosis of osteogenesis imperfecta usually depends on family history and clinical presentation characterized by a fracture (or fractures) during the prenatal period, at birth or in early childhood; genetic tests can confirm diagnosis. Osteogenesis imperfecta is caused by dominant autosomal mutations in the type I collagen coding genes (COL1A1 and COL1A2) in about 85% of individuals, affecting collagen quantity or structure. In the past decade, (mostly) recessive, dominant and X-linked defects in a wide variety of genes encoding proteins involved in type I collagen synthesis, processing, secretion and post-translational modification, as well as in proteins that regulate the differentiation and activity of bone-forming cells have been shown to cause osteogenesis imperfecta. The large number of causative genes has complicated the classic classification of the disease, and although a new genetic classification system is widely used, it is still debated. Phenotypic manifestations in many organs, in addition to bone, are reported, such as abnormalities in the cardiovascular and pulmonary systems, skin fragility, muscle weakness, hearing loss and dentinogenesis imperfecta. Management involves surgical and medical treatment of skeletal abnormalities, and treatment of other complications. More innovative approaches based on gene and cell therapy, and signalling pathway alterations, are under investigation.
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El-Ajouz S, Venturi E, Witschas K, Beech M, Wilson AD, Lindsay C, Eberhardt D, O'Brien F, Iida T, Nishi M, Takeshima H, Sitsapesan R. Dampened activity of ryanodine receptor channels in mutant skeletal muscle lacking TRIC-A. J Physiol 2017; 595:4769-4784. [PMID: 28387457 PMCID: PMC5509884 DOI: 10.1113/jp273550] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 03/29/2017] [Indexed: 01/02/2023] Open
Abstract
KEY POINTS The role of trimeric intracellular cation (TRIC) channels is not known, although evidence suggests they may regulate ryanodine receptors (RyR) via multiple mechanisms. We therefore investigated whether Tric-a gene knockout (KO) alters the single-channel function of skeletal RyR (RyR1). We find that RyR1 from Tric-a KO mice are more sensitive to inhibition by divalent cations, although they respond normally to cytosolic Ca2+ , ATP, caffeine and luminal Ca2+ . In the presence of Mg2+ , ATP cannot effectively activate RyR1 from Tric-a KO mice. Additionally, RyR1 from Tric-a KO mice are not activated by protein kinase A phosphorylation, demonstrating a defect in the ability of β-adrenergic stimulation to regulate sarcoplasmic reticulum (SR) Ca2+ -release. The defective RyR1 gating that we describe probably contributes significantly to the impaired SR Ca2+ -release observed in skeletal muscle from Tric-a KO mice, further highlighting the importance of TRIC-A for normal physiological regulation of SR Ca2+ -release in skeletal muscle. ABSTRACT The type A trimeric intracellular cation channel (TRIC-A) is a major component of the nuclear and sarcoplasmic reticulum (SR) membranes of cardiac and skeletal muscle, and is localized closely with ryanodine receptor (RyR) channels in the SR terminal cisternae. The skeletal muscle of Tric-a knockout (KO) mice is characterized by Ca2+ overloaded and swollen SR and by changes in the properties of SR Ca2+ release. We therefore investigated whether RyR1 gating behaviour is modified in the SR from Tric-a KO mice by incorporating native RyR1 into planar phospholipid bilayers under voltage-clamp conditions. We find that RyR1 channels from Tric-a KO mice respond normally to cytosolic Ca2+ , ATP, adenine, caffeine and to luminal Ca2+ . However, the channels are more sensitive to the inactivating effects of divalent cations, thus, in the presence of Mg2+ , ATP is inadequate as an activator. Additionally, channels are not characteristically activated by protein kinase A even though the phosphorylation levels of Ser2844 are similar to controls. The results of the present study suggest that TRIC-A functions as an excitatory modulator of RyR1 channels within the SR terminal cisternae. Importantly, this regulatory action of TRIC-A appears to be independent of (although additive to) any indirect consequences to RyR1 activity that arise as a result of K+ fluxes across the SR via TRIC-A.
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Affiliation(s)
- Sam El-Ajouz
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Elisa Venturi
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Katja Witschas
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Matthew Beech
- Department of Pharmacology, University of Oxford, Oxford, UK
| | | | - Chris Lindsay
- Department of Pharmacology, University of Oxford, Oxford, UK.,Department of Chemistry, University of Oxford, Oxford, UK
| | - David Eberhardt
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Fiona O'Brien
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Tsunaki Iida
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Miyuki Nishi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Hiroshi Takeshima
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
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26
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Structural basis for conductance through TRIC cation channels. Nat Commun 2017; 8:15103. [PMID: 28524849 PMCID: PMC5477506 DOI: 10.1038/ncomms15103] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Accepted: 02/28/2017] [Indexed: 01/08/2023] Open
Abstract
Mammalian TRICs function as K+-permeable cation channels that provide counter ions for Ca2+ handling in intracellular stores. Here we describe the structures of two prokaryotic homologues, archaeal SaTRIC and bacterial CpTRIC, showing that TRIC channels are symmetrical trimers with transmembrane pores through each protomer. Each pore holds a string of water molecules centred at kinked helices in two inverted-repeat triple-helix bundles (THBs). The pores are locked in a closed state by a hydrogen bond network at the C terminus of the THBs, which is lost when the pores assume an open conformation. The transition between the open and close states seems to be mediated by cation binding to conserved residues along the three-fold axis. Electrophysiology and mutagenesis studies show that prokaryotic TRICs have similar functional properties to those of mammalian TRICs and implicate the three-fold axis in the allosteric regulation of the channel. Trimeric intracellular cation channels (TRICs) elicit K+ currents to counteract luminal negative potential during Ca2+ release from intracellular stores. Here the authors present structures of prokaryotic TRICs in their open and closed states, obtaining molecular insight into TRICs' function.
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27
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Ou X, Guo J, Wang L, Yang H, Liu X, Sun J, Liu Z. Ion- and water-binding sites inside an occluded hourglass pore of a trimeric intracellular cation (TRIC) channel. BMC Biol 2017; 15:31. [PMID: 28431535 PMCID: PMC5401562 DOI: 10.1186/s12915-017-0372-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Accepted: 04/05/2017] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Trimeric intracellular cation (TRIC) channels are crucial for Ca2+ handling in eukaryotes and are involved in K+ uptake in prokaryotes. Recent studies on the representative members of eukaryotic and prokaryotic TRIC channels demonstrated that they form homotrimeric units with the ion-conducting pores contained within each individual monomer. RESULTS Here we report detailed insights into the ion- and water-binding sites inside the pore of a TRIC channel from Sulfolobus solfataricus (SsTRIC). Like the mammalian TRIC channels, SsTRIC is permeable to both K+ and Na+ with a slight preference for K+, and is nearly impermeable to Ca2+, Mg2+, or Cl-. In the 2.2-Å resolution K+-bound structure of SsTRIC, ion/water densities have been well resolved inside the pore. At the central region, a filter-like structure is shaped by the kinks on the second and fifth transmembrane helices and two nearby phenylalanine residues. Below the filter, the cytoplasmic vestibule is occluded by a plug-like motif attached to an array of pore-lining charged residues. CONCLUSIONS The asymmetric filter-like structure at the pore center of SsTRIC might serve as the basis for the channel to bind and select monovalent cations. A Velcro-like plug-pore interacting model has been proposed and suggests a unified framework accounting for the gating mechanisms of prokaryotic and eukaryotic TRIC channels.
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Affiliation(s)
- Xiaomin Ou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jianli Guo
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Longfei Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Hanting Yang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiuying Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jianyuan Sun
- State Key Laboratory of Brain & Cognitive Sciences, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhenfeng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
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28
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Kang H, Aryal A C S, Marini JC. Osteogenesis imperfecta: new genes reveal novel mechanisms in bone dysplasia. Transl Res 2017; 181:27-48. [PMID: 27914223 DOI: 10.1016/j.trsl.2016.11.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 11/04/2016] [Accepted: 11/07/2016] [Indexed: 12/20/2022]
Abstract
Osteogenesis imperfecta (OI) is a skeletal dysplasia characterized by fragile bones and short stature and known for its clinical and genetic heterogeneity which is now understood as a collagen-related disorder. During the last decade, research has made remarkable progress in identifying new OI-causing genes and beginning to understand the intertwined molecular and biochemical mechanisms of their gene products. Most cases of OI have dominant inheritance. Each new gene for recessive OI, and a recently identified gene for X-linked OI, has shed new light on its (often previously unsuspected) function in bone biology. Here, we summarize the literature that has contributed to our current understanding of the pathogenesis of OI.
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Affiliation(s)
- Heeseog Kang
- Section on Heritable Disorders of Bone and Extracellular Matrix, NICHD, NIH, Bethesda, Md
| | - Smriti Aryal A C
- Section on Heritable Disorders of Bone and Extracellular Matrix, NICHD, NIH, Bethesda, Md
| | - Joan C Marini
- Section on Heritable Disorders of Bone and Extracellular Matrix, NICHD, NIH, Bethesda, Md.
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29
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Abstract
Trimeric intracellular cation (TRIC) channel subtypes, namely TRIC-A and TRIC-B, are expressed in the endoplasmic/sarcoplasmic reticulum and nuclear envelope, and likely function as monovalent cation channels in various cell types. Our studies using knockout mice so far suggest that TRIC subtypes support Ca2+ release from intracellular stores by mediating counter-cationic fluxes. Several genetic mutations within the TRIC-B locus were recently identified in autosomal recessive osteogenesis imperfecta (OI) patients. However, the molecular mechanism by which the mutations cause human disease is not fully addressed. We found that Tric-b-knockout mice exhibit poor bone ossification and thus serve as an OI-model animal. Studies on Tric-b-knockout bones and cultured cell lines derived from the patients currently reveal the main part of the pathophysiological mechanism involved in the TRIC-B-mutated OI form. This mini-review focuses on the essential role of TRIC-B channels in bone ossification.
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30
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Pore architecture of TRIC channels and insights into their gating mechanism. Nature 2016; 538:537-541. [PMID: 27698420 DOI: 10.1038/nature19767] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 08/16/2016] [Indexed: 01/23/2023]
Abstract
Intracellular Ca2+ signalling processes are fundamental to muscle contraction, neurotransmitter release, cell growth and apoptosis. Release of Ca2+ from the intracellular stores is supported by a series of ion channels in sarcoplasmic or endoplasmic reticulum (SR/ER). Among them, two isoforms of the trimeric intracellular cation (TRIC) channel family, named TRIC-A and TRIC-B, modulate the release of Ca2+ through the ryanodine receptor or inositol triphosphate receptor, and maintain the homeostasis of ions within SR/ER lumen. Genetic ablations or mutations of TRIC channels are associated with hypertension, heart disease, respiratory defects and brittle bone disease. Despite the pivotal function of TRIC channels in Ca2+ signalling, their pore architectures and gating mechanisms remain unknown. Here we present the structures of TRIC-B1 and TRIC-B2 channels from Caenorhabditis elegans in complex with endogenous phosphatidylinositol-4,5-biphosphate (PtdIns(4,5)P2, also known as PIP2) lipid molecules. The TRIC-B1/B2 proteins and PIP2 assemble into a symmetrical homotrimeric complex. Each monomer contains an hourglass-shaped hydrophilic pore contained within a seven-transmembrane-helix domain. Structural and functional analyses unravel the central role of PIP2 in stabilizing the cytoplasmic gate of the ion permeation pathway and reveal a marked Ca2+-induced conformational change in a cytoplasmic loop above the gate. A mechanistic model has been proposed to account for the complex gating mechanism of TRIC channels.
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31
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Absence of the ER Cation Channel TMEM38B/TRIC-B Disrupts Intracellular Calcium Homeostasis and Dysregulates Collagen Synthesis in Recessive Osteogenesis Imperfecta. PLoS Genet 2016; 12:e1006156. [PMID: 27441836 PMCID: PMC4956114 DOI: 10.1371/journal.pgen.1006156] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 06/09/2016] [Indexed: 12/15/2022] Open
Abstract
Recessive osteogenesis imperfecta (OI) is caused by defects in proteins involved in post-translational interactions with type I collagen. Recently, a novel form of moderately severe OI caused by null mutations in TMEM38B was identified. TMEM38B encodes the ER membrane monovalent cation channel, TRIC-B, proposed to counterbalance IP3R-mediated Ca2+ release from intracellular stores. The molecular mechanisms by which TMEM38B mutations cause OI are unknown. We identified 3 probands with recessive defects in TMEM38B. TRIC-B protein is undetectable in proband fibroblasts and osteoblasts, although reduced TMEM38B transcripts are present. TRIC-B deficiency causes impaired release of ER luminal Ca2+, associated with deficient store-operated calcium entry, although SERCA and IP3R have normal stability. Notably, steady state ER Ca2+ is unchanged in TRIC-B deficiency, supporting a role for TRIC-B in the kinetics of ER calcium depletion and recovery. The disturbed Ca2+ flux causes ER stress and increased BiP, and dysregulates synthesis of proband type I collagen at multiple steps. Collagen helical lysine hydroxylation is reduced, while telopeptide hydroxylation is increased, despite increased LH1 and decreased Ca2+-dependent FKBP65, respectively. Although PDI levels are maintained, procollagen chain assembly is delayed in proband cells. The resulting misfolded collagen is substantially retained in TRIC-B null cells, consistent with a 50–70% reduction in secreted collagen. Lower-stability forms of collagen that elude proteasomal degradation are not incorporated into extracellular matrix, which contains only normal stability collagen, resulting in matrix insufficiency. These data support a role for TRIC-B in intracellular Ca2+ homeostasis, and demonstrate that absence of TMEM38B causes OI by dysregulation of calcium flux kinetics in the ER, impacting multiple collagen-specific chaperones and modifying enzymes. Osteogenesis imperfecta (OI) is a heritable disorder of connective tissues characterized by fracture susceptibility and growth deficiency. Most OI cases are caused by autosomal dominant mutations in the genes encoding type I collagen, COL1A1 and COL1A2. Delineation of novel gene defects causing dominant and recessive forms of OI has led to the understanding that the bone pathology results not only from abnormalities in type I collagen quantity and primary structure, but also from defects in post-translational modification, folding, intracellular transport and extracellular matrix incorporation. Recently, mutations in TMEM38B, which encodes the integral ER membrane K+ channel TRIC-B, have been identified as causative for the OI phenotype. However, the mechanism by which absence of TRIC-B causes OI has not been reported. Using cell lines established from three independent probands, we have demonstrated that absence of TRIC-B leads to abnormal ER Ca2+ flux and store-operated calcium entry (SOCE), although ER steady state Ca2+ is normal. Disruption of intracellular calcium dynamics alters the expression and activity of multiple collagen interacting chaperones and modifying enzymes within the ER. Thus TRIC-B deficiency causes OI by dysregulation of collagen synthesis, through the impairment of calcium-dependent gene expression and protein-protein interactions within the ER.
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32
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Zhao C, Ichimura A, Qian N, Iida T, Yamazaki D, Noma N, Asagiri M, Yamamoto K, Komazaki S, Sato C, Aoyama F, Sawaguchi A, Kakizawa S, Nishi M, Takeshima H. Mice lacking the intracellular cation channel TRIC-B have compromised collagen production and impaired bone mineralization. Sci Signal 2016; 9:ra49. [PMID: 27188440 DOI: 10.1126/scisignal.aad9055] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The trimeric intracellular cation (TRIC) channels TRIC-A and TRIC-B localize predominantly to the endoplasmic reticulum (ER) and likely support Ca(2+) release from intracellular stores by mediating cationic flux to maintain electrical neutrality. Deletion and point mutations in TRIC-B occur in families with autosomal recessive osteogenesis imperfecta. Tric-b knockout mice develop neonatal respiratory failure and exhibit poor bone ossification. We investigated the cellular defect causing the bone phenotype. Bone histology indicated collagen matrix deposition was reduced in Tric-b knockout mice. Osteoblasts, the bone-depositing cells, from Tric-b knockout mice exhibited reduced Ca(2+) release from ER and increased ER Ca(2+) content, which was associated with ER swelling. These cells also had impaired collagen release without a decrease in collagen-encoding transcripts, consistent with a defect in trafficking of collagen through ER. In contrast, osteoclasts, the bone-degrading cells, from Tric-b knockout mice were similar to those from wild-type mice. Thus, TRIC-B function is essential to support the production and release of large amounts of collagen by osteoblasts, which is necessary for bone mineralization.
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Affiliation(s)
- Chengzhu Zhao
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Atsuhiko Ichimura
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan. Keihanshin Consortium for Fostering the Next Generation of Global Leaders in Research (K-CONNEX), Kyoto University, Kyoto 606-8501, Japan
| | - Nianchao Qian
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Tsunaki Iida
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Daiju Yamazaki
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Naruto Noma
- Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Masataka Asagiri
- Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Koji Yamamoto
- Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | | | - Chikara Sato
- National Institute of Advanced Industrial Science and Technology, Ibaraki 305-8568, Japan
| | - Fumiyo Aoyama
- Faculty of Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Akira Sawaguchi
- Faculty of Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Sho Kakizawa
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Miyuki Nishi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Hiroshi Takeshima
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
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Abstract
Sarcoplasmic reticulum (SR) K+ channels are voltage-regulated channels that are thought to be actively gating when the membrane potential across the SR is close to zero as is expected physiologically. A characteristic of SR K+ channels is that they gate to subconductance open states but the relevance of the subconductance events and their contribution to the overall current flowing through the channels at physiological membrane potentials is not known. We have investigated the relationship between subconductance and full conductance openings and developed kinetic models to describe the voltage sensitivity of channel gating. Because there may be two subtypes of SR K+ channels (TRIC-A and TRIC-B) present in most tissues, to conduct our study on a homogeneous population of SR K+ channels, we incorporated SR vesicles derived from Tric-a knockout mice into artificial membranes to examine the remaining SR K+ channel (TRIC-B) function. The channels displayed very low open probability (Po) at negative potentials (≤0 mV) and opened predominantly to subconductance open states. Positive holding potentials primarily increased the frequency of subconductance state openings and thereby increased the number of subsequent transitions into the full open state, although a slowing of transitions back to the sublevels was also important. We investigated whether the subconductance gating could arise as an artifact of incomplete resolution of rapid transitions between full open and closed states; however, we were not able to produce a model that could fit the data as well as one that included multiple distinct current amplitudes. Our results suggest that the apparent subconductance openings will provide most of the K+ flux when the SR membrane potential is close to zero. The relative contribution played by openings to the full open state would increase if negative charge developed within the SR thus increasing the capacity of the channel to compensate for ionic imbalances.
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34
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Lv F, Xu XJ, Wang JY, Liu Y, Asan, Wang JW, Song LJ, Song YW, Jiang Y, Wang O, Xia WB, Xing XP, Li M. Two novel mutations in TMEM38B result in rare autosomal recessive osteogenesis imperfecta. J Hum Genet 2016; 61:539-45. [PMID: 26911354 DOI: 10.1038/jhg.2016.11] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 01/19/2016] [Accepted: 01/19/2016] [Indexed: 12/29/2022]
Abstract
Osteogenesis imperfecta (OI) is a group of clinically and genetically heterogeneous disorders characterized by decreased bone mass and recurrent bone fractures. Transmembrane protein 38B (TMEM38B) gene encodes trimeric intracellular cation channel type B (TRIC-B), mutations of which will lead to the rare form of autosomal recessive OI. Here we detected pathogenic gene mutations in TMEM38B and investigated its phenotypes in three children with OI from two non-consanguineous families of Chinese Han origin. The patients suffered from recurrent fractures, low bone mass, mild bone deformities and growth retardation, but did not have impaired hearing or dentinogenesis imperfecta. Next-generation sequencing and Sanger sequencing revealed a homozygous novel acceptor splice site variant (c.455-7T>G in intron 3, p.R151_G152insVL) in family 1 and a homozygous novel nonsense variant (c.507G>A in exon 4, p.W169X) in family 2. The parents of the probands were all heterozygous carriers of these mutations. We reported the phenotype and novel mutations in TMEM38B of OI for the first time in Chinese population. Our findings of the novel mutations in TMEM38B expand the pathogenic spectrum of OI and strengthen the role of TRIC-B in the pathogenesis of OI.
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Affiliation(s)
- Fang Lv
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
| | - Xiao-Jie Xu
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
| | - Jian-Yi Wang
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
| | - Yi Liu
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
| | - Asan
- Binhai Genomics Institute, Tianjin, China.,Tianjin Translational Genomics Center, Tianjin, China
| | - Jia-Wei Wang
- Binhai Genomics Institute, Tianjin, China.,Tianjin Translational Genomics Center, Tianjin, China
| | - Li-Jie Song
- Binhai Genomics Institute, Tianjin, China.,Tianjin Translational Genomics Center, Tianjin, China
| | - Yu-Wen Song
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
| | - Yan Jiang
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
| | - Ou Wang
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
| | - Wei-Bo Xia
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
| | - Xiao-Ping Xing
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
| | - Mei Li
- Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, China
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35
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Schneider JP, Pedersen L, Mühlfeld C, Ochs M. Staining histological lung sections with Sudan Black B or Sudan III for automated identification of alveolar epithelial type II cells. Acta Histochem 2015; 117:675-80. [PMID: 26558990 DOI: 10.1016/j.acthis.2015.10.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 10/14/2015] [Accepted: 10/20/2015] [Indexed: 12/28/2022]
Abstract
Alveolar epithelial type II (AE2) cells produce, store and secrete pulmonary surfactant and serve as progenitor cells for the alveolar epithelium. They are thus an interesting target in wide fields of pulmonary research. Stereological methods allow their quantification based on measurements on histological sections. A proper AE2 cell quantification, however, requires a method of tissue processing that results in little tissue shrinkage during processing. It was recently shown that a primary fixation with a mixture of glutaraldehyde and formaldehyde, postfixation with osmium tetroxide and uranyl acetate and embedding in glycol methacrylate fulfills this requirement. However, a proper quantification, furthermore, requires a secure identification of the cells under the microscope. Classical approaches using routine stainings, high magnifications and systematic uniform random sampling can result in a tedious counting procedure. In this article we show that Sudan Black B and Sudan III staining in combination with the previously described "low shrinkage method" of tissue processing result in good staining of lamellar bodies of AE2 cells (their storing organelles of surfactant) and thus provide a good signal of AE2 cells, which allows their easy and secure identification even at rather low magnifications. We further show that this signal enables automated detection of AE2 cells by image analysis, which should make this method a suitable staining method for the recently developed and more efficient proportionator sampling.
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36
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Takeshima H, Venturi E, Sitsapesan R. New and notable ion-channels in the sarcoplasmic/endoplasmic reticulum: do they support the process of intracellular Ca²⁺ release? J Physiol 2014; 593:3241-51. [PMID: 26228553 DOI: 10.1113/jphysiol.2014.281881] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 10/10/2014] [Indexed: 12/11/2022] Open
Abstract
Intracellular Ca(2+) release through ryanodine receptor (RyR) and inositol trisphosphate receptor (IP3 R) channels is supported by a complex network of additional proteins that are located in or near the Ca(2+) release sites. In this review, we focus, not on RyR/IP3 R, but on other ion-channels that are known to be present in the sarcoplasmic/endoplasmic reticulum (ER/SR) membranes. We review their putative physiological roles and the evidence suggesting that they may support the process of intracellular Ca(2+) release, either indirectly by manipulating ionic fluxes across the ER/SR membrane or by directly interacting with a Ca(2+) -release channel. These channels rarely receive scientific attention because of the general lack of information regarding their biochemical and/or electrophysiological characteristics makes it difficult to predict their physiological roles and their impact on SR Ca(2+) fluxes. We discuss the possible role of SR K(+) channels and, in parallel, detail the known biochemical and biophysical properties of the trimeric intracellular cation (TRIC) proteins and their possible biological and pathophysiological roles in ER/SR Ca(2+) release. We summarise what is known regarding Cl(-) channels in the ER/SR and the non-selective cation channels or putative 'Ca(2+) leak channels', including mitsugumin23 (MG23), pannexins, presenilins and the transient receptor potential (TRP) channels that are distributed across ER/SR membranes but which have not yet been fully characterised functionally.
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Affiliation(s)
- Hiroshi Takeshima
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Elisa Venturi
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
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Kuum M, Veksler V, Kaasik A. Potassium fluxes across the endoplasmic reticulum and their role in endoplasmic reticulum calcium homeostasis. Cell Calcium 2014; 58:79-85. [PMID: 25467968 DOI: 10.1016/j.ceca.2014.11.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 11/07/2014] [Accepted: 11/10/2014] [Indexed: 12/16/2022]
Abstract
There are a number of known and suspected channels and exchangers in the endoplasmic reticulum that may participate in potassium flux across its membrane. They include trimeric intracellular cation channels permeable for potassium, ATP-sensitive potassium channels, calcium-activated potassium channels and the potassium-hydrogen exchanger. Apart from trimeric intracellular cation channels, which are specific to the endoplasmic reticulum, other potassium channels are also expressed in the plasma membrane and/or mitochondria, and their specific role in the endoplasmic reticulum has not yet been fully established. In addition to these potassium-selective channels, the ryanodine receptor and, potentially, the inositol 1,4,5-trisphosphate receptor are permeable to potassium ions. Also, the role of potassium fluxes across the endoplasmic reticulum membrane has remained elusive. It has been proposed that their main role is to balance the charge movement that occurs during calcium release and uptake from or to the endoplasmic reticulum. This review aims to summarize current knowledge on endoplasmic reticulum potassium channels and fluxes and their potential role in endoplasmic reticulum calcium uptake and release.
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Affiliation(s)
- Malle Kuum
- Department of Pharmacology, Centre of Excellence for Translational Medicine, University of Tartu, Ravila 19, Tartu, Estonia
| | - Vladimir Veksler
- INSERM, U-769, Châtenay-Malabry F-92296, France; Univ Paris-Sud, Châtenay-Malabry F-92296, France
| | - Allen Kaasik
- Department of Pharmacology, Centre of Excellence for Translational Medicine, University of Tartu, Ravila 19, Tartu, Estonia.
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Boucherat O, Nadeau V, Bérubé-Simard FA, Charron J, Jeannotte L. Crucial requirement of ERK/MAPK signaling in respiratory tract development. Development 2014; 141:3197-211. [DOI: 10.1242/dev.110254] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The mammalian genome contains two ERK/MAP kinase genes, Mek1 and Mek2, which encode dual-specificity kinases responsible for ERK/MAP kinase activation. In order to define the function of the ERK/MAPK pathway in the lung development in mice, we performed tissue-specific deletions of Mek1 function on a Mek2 null background. Inactivation of both Mek genes in mesenchyme resulted in several phenotypes, including giant omphalocele, kyphosis, pulmonary hypoplasia, defective tracheal cartilage and death at birth. The absence of tracheal cartilage rings establishes the crucial role of intracellular signaling molecules in tracheal chondrogenesis and provides a putative mouse model for tracheomalacia. In vitro, the loss of Mek function in lung mesenchyme did not interfere with lung growth and branching, suggesting that both the reduced intrathoracic space due to the dysmorphic rib cage and the omphalocele impaired lung development in vivo. Conversely, Mek mutation in the respiratory epithelium caused lung agenesis, a phenotype resulting from the direct impact of the ERK/MAPK pathway on cell proliferation and survival. No tracheal epithelial cell differentiation occurred and no SOX2-positive progenitor cells were detected in mutants, implying a role for the ERK/MAPK pathway in trachea progenitor cell maintenance and differentiation. Moreover, these anomalies were phenocopied when the Erk1 and Erk2 genes were mutated in airway epithelium. Thus, the ERK/MAPK pathway is required for the integration of mesenchymal and epithelial signals essential for the development of the entire respiratory tract.
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Affiliation(s)
- Olivier Boucherat
- Centre de recherche sur le cancer de l'Université Laval, Centre Hospitalier Universitaire de Québec, L'Hôtel-Dieu de Québec, Québec, CanadaG1R 2J6
| | - Valérie Nadeau
- Centre de recherche sur le cancer de l'Université Laval, Centre Hospitalier Universitaire de Québec, L'Hôtel-Dieu de Québec, Québec, CanadaG1R 2J6
| | - Félix-Antoine Bérubé-Simard
- Centre de recherche sur le cancer de l'Université Laval, Centre Hospitalier Universitaire de Québec, L'Hôtel-Dieu de Québec, Québec, CanadaG1R 2J6
| | - Jean Charron
- Centre de recherche sur le cancer de l'Université Laval, Centre Hospitalier Universitaire de Québec, L'Hôtel-Dieu de Québec, Québec, CanadaG1R 2J6
- Department of Molecular Biology, Medical Biochemistry and Pathology, Université Laval, Québec, Canada G1V 0A6
| | - Lucie Jeannotte
- Centre de recherche sur le cancer de l'Université Laval, Centre Hospitalier Universitaire de Québec, L'Hôtel-Dieu de Québec, Québec, CanadaG1R 2J6
- Department of Molecular Biology, Medical Biochemistry and Pathology, Université Laval, Québec, Canada G1V 0A6
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39
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Rubinato E, Morgan A, D'Eustacchio A, Pecile V, Gortani G, Gasparini P, Faletra F. A novel deletion mutation involving TMEM38B in a patient with autosomal recessive osteogenesis imperfecta. Gene 2014; 545:290-2. [DOI: 10.1016/j.gene.2014.05.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Revised: 05/04/2014] [Accepted: 05/09/2014] [Indexed: 10/25/2022]
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40
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Zhou X, Lin P, Yamazaki D, Park KH, Komazaki S, Chen SRW, Takeshima H, Ma J. Trimeric intracellular cation channels and sarcoplasmic/endoplasmic reticulum calcium homeostasis. Circ Res 2014; 114:706-16. [PMID: 24526676 DOI: 10.1161/circresaha.114.301816] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Trimeric intracellular cation channels (TRIC) represents a novel class of trimeric intracellular cation channels. Two TRIC isoforms have been identified in both the human and the mouse genomes: TRIC-A, a subtype predominantly expressed in the sarcoplasmic reticulum (SR) of muscle cells, and TRIC-B, a ubiquitous subtype expressed in the endoplasmic reticulum (ER) of all tissues. Genetic ablation of either TRIC-A or TRIC-B leads to compromised K(+) permeation and Ca(2+) release across the SR/ER membrane, supporting the hypothesis that TRIC channels provide a counter balancing K(+) flux that reduces SR/ER membrane depolarization for maintenance of the electrochemical gradient that drives SR/ER Ca(2+) release. TRIC-A and TRIC-B seem to have differential functions in Ca(2+) signaling in excitable and nonexcitable cells. Tric-a(-/-) mice display defective Ca(2+) sparks and spontaneous transient outward currents in arterial smooth muscle and develop hypertension, in addition to skeletal muscle dysfunction. Knockout of TRIC-B results in abnormal IP3 receptor-mediated Ca(2+) release in airway epithelial cells, respiratory defects, and neonatal lethality. Double knockout mice lacking both TRIC-A and TRIC-B show embryonic lethality as a result of cardiac arrest. Such an aggravated lethality indicates that TRIC-A and TRIC-B share complementary physiological functions in Ca(2+) signaling in embryonic cardiomyocytes. Tric-a(-/-) and Tric-b(+/-) mice are viable and susceptible to stress-induced heart failure. Recent evidence suggests that TRIC-A directly modulates the function of the cardiac ryanodine receptor 2 Ca(2+) release channel, which in turn controls store-overload-induced Ca(2+) release from the SR. Thus, the TRIC channels, in addition to providing a countercurrent for SR/ER Ca(2+) release, may also function as accessory proteins that directly modulate the ryanodine receptor/IP3 receptor channel functions.
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Affiliation(s)
- Xinyu Zhou
- From the Department of Surgery, Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus (X.Z., P.L., K.H.P., J.M.); Department of Biological Chemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Kyoto, Japan (D.Y., H.T.); Department of Anatomy, Saitama Medical University, Saitama, Japan (S.K.); and Departments of Physiology and Pharmacology, and Biochemistry and Molecular Biology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada (W.C.)
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41
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A molecular ensemble in the rER for procollagen maturation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2479-91. [DOI: 10.1016/j.bbamcr.2013.04.008] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 04/06/2013] [Accepted: 04/08/2013] [Indexed: 01/18/2023]
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42
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Lam AK, Galione A. The endoplasmic reticulum and junctional membrane communication during calcium signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2542-59. [DOI: 10.1016/j.bbamcr.2013.06.004] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 06/03/2013] [Accepted: 06/03/2013] [Indexed: 12/13/2022]
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43
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Autosomal Recessive Osteogenesis Imperfecta: A Puzzle for Bone Formation, Structure and Function. CURRENT GENETIC MEDICINE REPORTS 2013. [DOI: 10.1007/s40142-013-0026-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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44
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Tao S, Yamazaki D, Komazaki S, Zhao C, Iida T, Kakizawa S, Imaizumi Y, Takeshima H. Facilitated hyperpolarization signaling in vascular smooth muscle-overexpressing TRIC-A channels. J Biol Chem 2013; 288:15581-9. [PMID: 23592776 DOI: 10.1074/jbc.m112.435396] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The TRIC channel subtypes, namely TRIC-A and TRIC-B, are intracellular monovalent cation-specific channels and likely mediate counterion movements to support efficient Ca(2+) release from the sarco/endoplasmic reticulum. Vascular smooth muscle cells (VSMCs) contain both TRIC subtypes and two Ca(2+) release mechanisms; incidental opening of ryanodine receptors (RyRs) generates local Ca(2+) sparks to induce hyperpolarization and relaxation, whereas agonist-induced activation of inositol trisphosphate receptors produces global Ca(2+) transients causing contraction. Tric-a knock-out mice develop hypertension due to insufficient RyR-mediated Ca(2+) sparks in VSMCs. Here we describe transgenic mice overexpressing TRIC-A channels under the control of a smooth muscle cell-specific promoter. The transgenic mice developed congenital hypotension. In Tric-a-overexpressing VSMCs from the transgenic mice, the resting membrane potential decreased because RyR-mediated Ca(2+) sparks were facilitated and cell surface Ca(2+)-dependent K(+) channels were hyperactivated. Under such hyperpolarized conditions, L-type Ca(2+) channels were inactivated, and thus, the resting intracellular Ca(2+) levels were reduced in Tric-a-overexpressing VSMCs. Moreover, Tric-a overexpression impaired inositol trisphosphate-sensitive stores to diminish agonist-induced Ca(2+) signaling in VSMCs. These altered features likely reduced vascular tonus leading to the hypotensive phenotype. Our Tric-a-transgenic mice together with Tric-a knock-out mice indicate that TRIC-A channel density in VSMCs is responsible for controlling basal blood pressure at the whole-animal level.
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Affiliation(s)
- Shengchen Tao
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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45
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Venturi E, Matyjaszkiewicz A, Pitt SJ, Tsaneva-Atanasova K, Nishi M, Yamazaki D, Takeshima H, Sitsapesan R. TRIC-B channels display labile gating: evidence from the TRIC-A knockout mouse model. Pflugers Arch 2013; 465:1135-48. [PMID: 23467973 PMCID: PMC3732801 DOI: 10.1007/s00424-013-1251-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 01/24/2013] [Accepted: 02/11/2013] [Indexed: 11/25/2022]
Abstract
Sarcoplasmic/endoplasmic reticulum (SR) and nuclear membranes contain two related cation channels named TRIC-A and TRIC-B. In many tissues, both subtypes are co-expressed, making it impossible to distinguish the distinct single-channel properties of each subtype. We therefore incorporated skeletal muscle SR vesicles derived from Tric-a-knockout mice into bilayers in order to characterise the biophysical properties of native TRIC-B without possible misclassification of the channels as TRIC-A, and without potential distortion of functional properties by detergent purification protocols. The native TRIC-B channels were ideally selective for cations. In symmetrical 210 mM K+, the maximum (full) open channel level (199 pS) was equivalent to that observed when wild-type SR vesicles were incorporated into bilayers. Analysis of TRIC-B gating revealed complex and variable behaviour. Four main sub-conductance levels were observed at approximately 80 % (161 pS), 60 % (123 pS), 46 % (93 pS), and 30 % (60 pS) of the full open state. Seventy-five percent of the channels were voltage sensitive with Po being markedly reduced at negative holding potentials. The frequent, rapid transitions between TRIC-B sub-conductance states prevented development of reliable gating models using conventional single-channel analysis. Instead, we used mean-variance plots to highlight key features of TRIC-B gating in a more accurate and visually useful manner. Our study provides the first biophysical characterisation of native TRIC-B channels and indicates that this channel would be suited to provide counter current in response to Ca2+ release from the SR. Further experiments are required to distinguish the distinct functional properties of TRIC-A and TRIC-B and understand their individual but complementary physiological roles.
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Affiliation(s)
- Elisa Venturi
- School of Physiology & Pharmacology, NSQI and Bristol Heart Institute, University of Bristol, Bristol, BS8 1TD UK
| | - Antoni Matyjaszkiewicz
- School of Physiology & Pharmacology, NSQI and Bristol Heart Institute, University of Bristol, Bristol, BS8 1TD UK
- Department of Engineering Mathematics, University of Bristol, Bristol, BS8 1TR UK
- Bristol Centre for Complexity Sciences, University of Bristol, Bristol, BS8 1TR UK
| | - Samantha J. Pitt
- School of Medicine, University of St Andrews, St Andrews, KY16 9TF UK
| | | | - Miyuki Nishi
- Graduate School of Pharmaceutical Sciences and Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, 606-8501 Japan
| | - Daiju Yamazaki
- Graduate School of Pharmaceutical Sciences and Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, 606-8501 Japan
| | - Hiroshi Takeshima
- Graduate School of Pharmaceutical Sciences and Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, 606-8501 Japan
| | - Rebecca Sitsapesan
- School of Physiology & Pharmacology, NSQI and Bristol Heart Institute, University of Bristol, Bristol, BS8 1TD UK
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46
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Sayin VI, Nilton A, Ibrahim MX, Ågren P, Larsson E, Petit MM, Hultén LM, Ståhlman M, Johansson BR, Bergo MO, Lindahl P. Zfp148 deficiency causes lung maturation defects and lethality in newborn mice that are rescued by deletion of p53 or antioxidant treatment. PLoS One 2013; 8:e55720. [PMID: 23405202 PMCID: PMC3566028 DOI: 10.1371/journal.pone.0055720] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 12/29/2012] [Indexed: 12/18/2022] Open
Abstract
The transcription factor Zfp148 (Zbp-89, BFCOL, BERF1, htβ) interacts physically with the tumor suppressor p53 and is implicated in cell cycle control, but the physiological role of Zfp148 remains unknown. Here we show that Zfp148 deficiency leads to respiratory distress and lethality in newborn mice. Zfp148 deficiency prevented structural maturation of the prenatal lung without affecting type II cell differentiation or surfactant production. BrdU analyses revealed that Zfp148 deficiency caused proliferation arrest of pulmonary cells at E18.5–19.5. Similarly, Zfp148-deficient fibroblasts exhibited proliferative arrest that was dependent on p53, raising the possibility that cell stress is part of the underlying mechanism. Indeed, Zfp148 deficiency lowered the threshold for activation of p53 under oxidative conditions. Moreover, both in vivo and cellular phenotypes were rescued on Trp53+/− or Trp53−/− backgrounds and by antioxidant treatment. Thus, Zfp148 prevents respiratory distress and lethality in newborn mice by attenuating oxidative stress–dependent p53-activity during the saccular stage of lung development. Our results establish Zfp148 as a novel player in mammalian lung maturation and demonstrate that Zfp148 is critical for cell cycle progression in vivo.
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MESH Headings
- Animals
- Animals, Newborn
- Antioxidants/pharmacology
- Apoptosis
- Blotting, Southern
- Blotting, Western
- Cell Cycle
- Cell Proliferation
- Cells, Cultured
- DNA-Binding Proteins/physiology
- Embryo, Mammalian/cytology
- Embryo, Mammalian/drug effects
- Embryo, Mammalian/metabolism
- Female
- Fibroblasts/cytology
- Fibroblasts/drug effects
- Fibroblasts/metabolism
- Gene Deletion
- Genes, Lethal
- Immunoenzyme Techniques
- Lung/drug effects
- Lung/embryology
- Lung/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Oxidative Stress/drug effects
- RNA, Messenger/genetics
- Real-Time Polymerase Chain Reaction
- Respiratory Tract Diseases/genetics
- Respiratory Tract Diseases/pathology
- Respiratory Tract Diseases/prevention & control
- Reverse Transcriptase Polymerase Chain Reaction
- Transcription Factors/physiology
- Tumor Suppressor Protein p53/deficiency
- Tumor Suppressor Protein p53/genetics
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Affiliation(s)
- Volkan I. Sayin
- Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
- Department of Biochemistry, Institute of Biomedicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Anna Nilton
- Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Mohamed X. Ibrahim
- Sahlgrenska Cancer Center, Institute of Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Pia Ågren
- Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Erik Larsson
- Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
- Department of Biochemistry, Institute of Biomedicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Marleen M. Petit
- Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Lillemor Mattsson Hultén
- Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Marcus Ståhlman
- Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Bengt R. Johansson
- Department of Biochemistry, Institute of Biomedicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Martin O. Bergo
- Sahlgrenska Cancer Center, Institute of Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Per Lindahl
- Wallenberg Laboratory, Institute of Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
- Department of Biochemistry, Institute of Biomedicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
- * E-mail:
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47
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TRIC channels supporting efficient Ca2+ release from intracellular stores. Pflugers Arch 2012; 465:187-95. [DOI: 10.1007/s00424-012-1197-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 11/30/2012] [Accepted: 11/30/2012] [Indexed: 12/22/2022]
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48
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Effect of aging on calcium signaling in C57Bl6J mouse cerebral arteries. Pflugers Arch 2012; 465:829-38. [DOI: 10.1007/s00424-012-1195-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 11/28/2012] [Accepted: 11/29/2012] [Indexed: 01/08/2023]
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Yamazaki D. [TRIC(trimeric intracellular cation)-A channels contribute to blood pressure maintenance in vascular smooth muscle]. YAKUGAKU ZASSHI 2012; 132:1037-43. [PMID: 23023421 DOI: 10.1248/yakushi.132.1037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
TRIC (trimeric intracellular cation) channel subtypes, namely TRIC-A and TRIC-B, are intracellular monovalent cation channels postulated to mediate counter-ion movements facilitating physiological Ca²⁺ release from intracellular stores. Tric-a-knockout mice developed hypertension during the daytime due to enhanced myogenic tone in resistance arteries. There are two Ca²⁺ release mechanisms in vascular smooth muscle cells (VSMCs); incidental opening of ryanodine receptors (RyRs) generates local Ca²⁺ sparks to induce hyperpolarization, while agonist-induced activation of inositol trisphosphate receptors (IP₃Rs) evokes global Ca²⁺ transients causing contraction. Tric-a gene ablation inhibited RyR-mediated hyperpolarization signaling to stimulate voltage-dependent Ca²⁺ influx, and adversely enhanced IP₃R-mediated Ca²⁺ transients by overloading Ca²⁺ stores in VSMCs. Therefore, TRIC-A channels contribute to maintaining blood pressure in vascular smooth muscles.
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Affiliation(s)
- Daiju Yamazaki
- Department of Biological Chemistry, Graduate School of Phamaceutical Sciences, Kyoto University, Japan.
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Dietl P, Haller T, Frick M. Spatio-temporal aspects, pathways and actions of Ca(2+) in surfactant secreting pulmonary alveolar type II pneumocytes. Cell Calcium 2012; 52:296-302. [PMID: 22591642 DOI: 10.1016/j.ceca.2012.04.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 04/11/2012] [Accepted: 04/18/2012] [Indexed: 01/16/2023]
Abstract
The type II cell of the pulmonary alveolus is a polarized epithelial cell that secretes surfactant into the alveolar space by regulated exocytosis of lamellar bodies (LBs). This process consists of multiple sequential steps and is correlated to elevations of the cytoplasmic Ca(2+) concentration ([Ca(2+)](c)) required for extended periods of secretory activity. Both chemical (purinergic) and mechanical (cell stretch or exposure to an air-liquid interface) stimuli give rise to complex Ca(2+) signals (such as Ca(2+) peaks, spikes and plateaus) that differ in shape, origin and spatio-temporal behavior. This review summarizes current knowledge about Ca(2+) channels, including vesicular P2X4 purinoceptors, in type II cells and associated signaling cascades within the alveolar microenvironment, and relates stimulus-dependent activation of these pathways with distinct stages of surfactant secretion, including pre- and postfusion stages of LB exocytosis.
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Affiliation(s)
- Paul Dietl
- Institute of General Physiology, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
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