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Kopach O, Pivneva T, Fedirko N, Voitenko N. Mitochondrial malfunction mediates impaired cholinergic Ca 2+ signalling and submandibular salivary gland dysfunction in diabetes. Neuropharmacology 2024; 243:109789. [PMID: 37972885 DOI: 10.1016/j.neuropharm.2023.109789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 10/23/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023]
Abstract
Xerostomia (dry-mouth syndrome) is a painful and debilitating condition that frequently occurs in individuals with diabetes and is associated with impaired saliva production and salivary gland hypofunction. Saliva fluid production relies on Ca2+-coupled secretion driven by neurotransmitter stimulation of submandibular acinar cells. Although impairments in intracellular Ca2+ signalling have been reported in various xerostomia models, the specific Ca2+-dependent mechanisms underlying saliva fluid hypofunction in diabetes remain unclear. In this study, we show that diabetic animals exhibit severe xerostomia, evident by reduced saliva flow rate, diminished total protein content, and decreased amylase activity in the saliva secreted by submandibular glands. These impairments remained resistant to exogenous cholinergic stimulation. In submandibular acinar cells, the intracellular Ca2+ signals evoked by cholinergic stimulation were reduced and delayed in diabetes, caused by malfunctioning mitochondria. Upon initiation of cholinergic-evoked Ca2+ signals, mitochondria accumulate higher Ca2+ and fail to redistribute Ca2+ influx and facilitate the store-operated Ca2+ entry effectively. Structural damage to mitochondria was evident in the acinar cells in diabetes. These findings provide insights into the potential targeting of malfunctioning mitochondria for the treatment of diabetic xerostomia as an alternative strategy to the existing pharmacotherapeutic approaches. This article is part of the Special Issue on "Ukrainian Neuroscience".
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Affiliation(s)
- Olga Kopach
- Bogomoletz Institute of Physiology, Kyiv, Ukraine; Queen Square Institute of Neurology, University College London, London, UK.
| | - Tetyana Pivneva
- Bogomoletz Institute of Physiology, Kyiv, Ukraine; Kyiv Academic University, Kyiv, Ukraine
| | | | - Nana Voitenko
- Kyiv Academic University, Kyiv, Ukraine; Dobrobut Academy Medical School, Kyiv, Ukraine
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Inagaki S, Suzuki Y, Kawasaki K, Kondo R, Imaizumi Y, Yamamura H. Mitofusin 2 positively regulates Ca 2+ signaling by tethering the sarcoplasmic reticulum and mitochondria in rat aortic smooth muscle cells. Am J Physiol Cell Physiol 2022; 323:C295-C305. [PMID: 35704692 DOI: 10.1152/ajpcell.00274.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mitochondria buffer cytosolic Ca2+increases following Ca2+ influx from extracellular spaces and Ca2+ release from intracellular Ca2+ store sites under physiological circumstances. Therefore, close contact of mitochondria with the sarcoplasmic reticulum (SR) is required for maintaining Ca2+ homeostasis. Mitofusin 2 (Mfn2) localizes in both mitochondrial and SR membranes, and is hypothesized to optimize the distance and Ca2+ transfer between these organelles. However, the physiological significance of Mfn2 in vascular smooth muscle cells (VSMCs) is poorly understood. In the present study, the role of Mfn2 in the physical and functional couplings between SR and mitochondria was examined in rat aortic smooth muscle cells (rASMCs) by confocal and electron microscope imaging. When Mfn2 was knocked-down using siRNA in rASMCs, the mean distance between these organelles was extended from 16.2 to 21.6 nm. The increase in the cytosolic Ca2+ concentration ([Ca2+]cyt) induced by 100 nM arginine vasopressin (AVP) was not affected by Mfn2 siRNA knockdown, whereas cytosolic Ca2+ removal was slower after Mfn2 knockdown. Following the AVP-induced [Ca2+]cyt increase, mitochondrial Ca2+ uptake and Ca2+ refill into the SR were attenuated by Mfn2 knockdown. In addition, Mfn2-knockdown cells exhibited a loss of mitochondrial membrane potential (ΔΨmito) and lower ATP levels in mitochondria. Moreover, Mfn2 knockdown inhibited cell proliferation. In contrast, Mfn2 overexpression increased ΔΨmito and cell growth. This study strongly suggests that Mfn2 is responsible for SR-mitochondria Ca2+ signaling by tethering mitochondria to SR, thereby regulating ATP production and proliferation of VSMCs.
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Affiliation(s)
- Sou Inagaki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Yoshiaki Suzuki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Keisuke Kawasaki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Rubii Kondo
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Yuji Imaizumi
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Aichi, Japan
| | - Hisao Yamamura
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
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Resveratrol Treatment in Human Parkin-Mutant Fibroblasts Modulates cAMP and Calcium Homeostasis Regulating the Expression of Mitochondria-Associated Membranes Resident Proteins. Biomolecules 2021; 11:biom11101511. [PMID: 34680144 PMCID: PMC8534032 DOI: 10.3390/biom11101511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/12/2021] [Accepted: 10/13/2021] [Indexed: 12/16/2022] Open
Abstract
Parkin plays an important role in ensuring efficient mitochondrial function and calcium homeostasis. Parkin-mutant human fibroblasts, with defective oxidative phosphorylation activity, showed high basal cAMP level likely ascribed to increased activity/expression of soluble adenylyl cyclase and/or low expression/activity of the phosphodiesterase isoform 4 and to a higher Ca2+ level. Overall, these findings support the existence, in parkin-mutant fibroblasts, of an abnormal Ca2+ and cAMP homeostasis in mitochondria. In our previous studies resveratrol treatment of parkin-mutant fibroblasts induced a partial rescue of mitochondrial functions associated with stimulation of the AMPK/SIRT1/PGC-1α pathway. In this study we provide additional evidence of the potential beneficial effects of resveratrol inducing an increase in the pre-existing high Ca2+ level and remodulation of the cAMP homeostasis in parkin-mutant fibroblasts. Consistently, we report in these fibroblasts higher expression of proteins implicated in the tethering of ER and mitochondrial contact sites along with their renormalization after resveratrol treatment. On this basis we hypothesize that resveratrol-mediated enhancement of the Ca2+ level, fine-tuned by the ER-mitochondria Ca2+ crosstalk, might modulate the pAMPK/AMPK pathway in parkin-mutant fibroblasts.
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Yao Y, Dong S, Zhu C, Hu M, Du B, Tong X. [Down-regulation of pannexin 2 channel enhances cisplatin-induced apoptosis in testicular cancer I-10 cells]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2020; 40:1090-1096. [PMID: 32895173 DOI: 10.12122/j.issn.1673-4254.2020.08.04] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To investigate the effect of down-regulation of pannexin 2 (Panx-2) channels on cisplatin-induced apoptosis in I-10 cells. METHODS The expression of Panx-2 protein in testicular cancer cells was detected with Western blotting. The testicular cancer cell line I-10 was transfected with two short hairpin RNA (shRNA1 and shRNA2) via Lipofectamine2000, the empty vector (NC group) or Lipofectamine2000 (blank control group), and the changes in the expression of Panx-2 was detected with Western blotting. The effects of transfection with a Panx-2 inhibitor on surviving fraction of the cells treated with cisplatin (16 μmol/L) for 24 h, 48 h and 72 h was assessed with MTT assay, and the clonogenic capacity of the cells was evaluated with colony-forming assay. At 8 h after incubation with 16 μmol/L cisplatin, AnnexinV/PI double staining was used to detect the early apoptosis of the cells. After 24 h of treatment with 16 μmol/L cisplatin, the cells were examined for expressions of caspase-3, Bcl-2 and Bax using Western blotting. RESULTS The expression of Panx-2 was significantly increased in cisplatin-resistant I-10/DDP (P < 0.001) cells and Tcam-2/DDP (P < 0.01) cells as compared with I-10 cells and Tcam-2 cells. Transfection of I-10 cells with shRNA1 and shRNA2 resulted in significantly decreased Panx-2 expression (P < 0.05) and significantly reduced cell surviving fraction (P < 0.001). In the presence of cisplatin, the cells in NC group showed a higher clonogenic efficiency than those in shRNA1 and shRNA2 groups (P < 0.001). The early-stage apoptosis rate of the cells in shRNA1 and shRNA2 groups were significantly higher than that in NC group (P < 0.01). Panx-2 knockdown in I-10 cells significantly increased caspase-3 and Bax expressions (P < 0.05) and significantly decreased the expression of Bcl-2 (P < 0.01). CONCLUSIONS Down-regulation of Panx-2 channel enhances cisplatin-induced apoptosis in cultured testicular cancer cells.
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Affiliation(s)
- Yanxue Yao
- School of Pharmacy, Bengbu Medical College, Bengbu 233030, China
| | - Shuying Dong
- School of Pharmacy, Bengbu Medical College, Bengbu 233030, China
| | - Chenlu Zhu
- School of Pharmacy, Bengbu Medical College, Bengbu 233030, China
| | - Miao Hu
- School of Pharmacy, Bengbu Medical College, Bengbu 233030, China
| | - Baolong Du
- School of Pharmacy, Bengbu Medical College, Bengbu 233030, China
| | - Xuhui Tong
- School of Pharmacy, Bengbu Medical College, Bengbu 233030, China
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Agrawal RR, Montesinos J, Larrea D, Area-Gomez E, Pera M. The silence of the fats: A MAM's story about Alzheimer. Neurobiol Dis 2020; 145:105062. [PMID: 32866617 DOI: 10.1016/j.nbd.2020.105062] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 08/07/2020] [Accepted: 08/22/2020] [Indexed: 02/07/2023] Open
Abstract
The discovery of contact sites was a breakthrough in cell biology. We have learned that an organelle cannot function in isolation, and that many cellular functions depend on communication between two or more organelles. One such contact site results from the close apposition of the endoplasmic reticulum (ER) and mitochondria, known as mitochondria-associated ER membranes (MAMs). These intracellular lipid rafts serve as hubs for the regulation of cellular lipid and calcium homeostasis, and a growing body of evidence indicates that MAM domains modulate cellular function in both health and disease. Indeed, MAM dysfunction has been described as a key event in Alzheimer disease (AD) pathogenesis. Our most recent work shows that, by means of its affinity for cholesterol, APP-C99 accumulates in MAM domains of the ER and induces the uptake of extracellular cholesterol as well as its trafficking from the plasma membrane to the ER. As a result, MAM functionality becomes chronically upregulated while undergoing continual turnover. The goal of this review is to discuss the consequences of C99 elevation in AD, specifically the upregulation of cholesterol trafficking and MAM activity, which abrogate cellular lipid homeostasis and disrupt the lipid composition of cellular membranes. Overall, we present a novel framework for AD pathogenesis that can be linked to the many complex alterations that occur during disease progression, and that may open a door to new therapeutic strategies.
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Affiliation(s)
- Rishi R Agrawal
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Jorge Montesinos
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Delfina Larrea
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Estela Area-Gomez
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, 10032, USA; Department of Neurology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Marta Pera
- Departament of Basic Sciences, Facultat de Medicina I Ciències de la Salut, Universitat Internacional de Catalunya (UIC), Sant Cugat del Vallés, 08195, Spain.
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Cortes-Troncoso J, Jang SI, Perez P, Hidalgo J, Ikeuchi T, Greenwell-Wild T, Warner BM, Moutsopoulos NM, Alevizos I. T cell exosome-derived miR-142-3p impairs glandular cell function in Sjögren's syndrome. JCI Insight 2020; 5:133497. [PMID: 32376798 DOI: 10.1172/jci.insight.133497] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 04/08/2020] [Indexed: 11/17/2022] Open
Abstract
Sjögren's syndrome (SS) is a systemic autoimmune disease that mainly affects exocrine salivary and lacrimal glands. Local inflammation in the glands is thought to trigger glandular dysfunction and symptoms of dryness. However, the mechanisms underlying these processes are incompletely understood. Our work suggests T cell exosome-derived miR-142-3p as a pathogenic driver of immunopathology in SS. We first document miR-142-3p expression in the salivary glands of patients with SS, both in epithelial gland cells and within T cells of the inflammatory infiltrate, but not in healthy volunteers. Next, we show that activated T cells secreted exosomes containing miR-142-3p, which transferred into glandular cells. Finally, we uncover a functional role of miR-142-3p-containing exosomes in glandular cell dysfunction. We find that miR-142-3p targets key elements of intracellular Ca2+ signaling and cAMP production - sarco(endo)plasmic reticulum Ca2+ ATPase 2b (SERCA2B), ryanodine receptor 2 (RyR2), and adenylate cyclase 9 (AC9) - leading to restricted cAMP production, altered calcium signaling, and decreased protein production from salivary gland cells. Our work provides evidence for a functional role of the miR-142-3p in SS pathogenesis and promotes the concept that T cell activation may directly impair epithelial cell function through secretion of miRNA-containing exosomes.
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Affiliation(s)
- Juan Cortes-Troncoso
- Sjögren's Syndrome and Salivary Gland Dysfunction Unit.,Oral Immunity and Inflammation Section, and
| | - Shyh-Ing Jang
- Sjögren's Syndrome and Salivary Gland Dysfunction Unit
| | - Paola Perez
- Adeno-Associated Virus Biology Section, National Institute of Dental and Craniofacial Research (NIDCR), NIH, Bethesda, Maryland, USA
| | - Jorge Hidalgo
- Program of Physiology and Biophysics, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile
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Pannexin 2 Localizes at ER-Mitochondria Contact Sites. Cancers (Basel) 2019; 11:cancers11030343. [PMID: 30862038 PMCID: PMC6468579 DOI: 10.3390/cancers11030343] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/22/2019] [Accepted: 02/27/2019] [Indexed: 01/02/2023] Open
Abstract
Endomembrane specialization allows functional compartmentalization but imposes physical constraints to information flow within the cell. However, the evolution of an endomembrane system was associated with the emergence of contact sites facilitating communication between membrane-bound organelles. Contact sites between the endoplasmic reticulum (ER) and mitochondria are highly conserved in terms of their morphological features but show surprising molecular diversity within and across eukaryote species. ER-mitochondria contact sites are thought to regulate key processes in oncogenesis but their molecular composition remains poorly characterized in mammalian cells. In this study, we investigate the localization of pannexin 2 (Panx2), a membrane channel protein showing tumor-suppressing properties in cancer cells. Using a combination of subcellular fractionation, particle tracking in live-cell, and immunogold electron microscopy, we show that Panx2 localizes at ER-mitochondria contact sites in mammalian cells and sensitizes cells to apoptotic stimuli.
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Shi Y, Wang Y, Wei H. Dantrolene : From Malignant Hyperthermia to Alzheimer's Disease. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2019; 18:668-676. [PMID: 29921212 PMCID: PMC7754833 DOI: 10.2174/1871527317666180619162649] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Revised: 05/07/2018] [Accepted: 06/13/2018] [Indexed: 12/12/2022]
Abstract
Dantrolene, a ryanodine receptor antagonist, is primarily known as the only clinically acceptable and effective treatment for Malignant Hyperthermia (MH). Inhibition of Ryanodine Receptor (RyR) by dantrolene decreases the abnormal calcium release from the Sarcoplasmic Reticulum (SR) or Endoplasmic Reticulum (ER), where RyR is located. Recently, emerging researches on dissociated cells, brains slices, live animal models and patients have demonstrated that altered RyR expression and function can also play a vital role in the pathogenesis of Alzheimer's Disease (AD). Therefore, dantrolene is now widely studied as a novel treatment for AD, targeting the blockade of RyR channels or another alternative pathway, such as the inhibitory effects of NMDA glutamate receptors and the effects of ER-mitochondria connection. However, the therapeutic effects are not consistent. In this review, we focus on the relationship between the altered RyR expression and function and the pathogenesis of AD, and the potential application of dantrolene as a novel treatment for the disease.
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Affiliation(s)
- Yun Shi
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, 305 John Morgan Building, 3620 Hamilton Walk, Philadelphia, PA 19104, USA
- Department of Anesthesiology, Children’s Hospital of Fudan University, Shanghai, China
| | - Yong Wang
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, 305 John Morgan Building, 3620 Hamilton Walk, Philadelphia, PA 19104, USA
- Department of Anesthesiology, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510405, China
| | - Huafeng Wei
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, 305 John Morgan Building, 3620 Hamilton Walk, Philadelphia, PA 19104, USA
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Rosiglitazone rescues human neural stem cells from amyloid-beta induced ER stress via PPARγ dependent signaling. Exp Cell Res 2018; 370:312-321. [DOI: 10.1016/j.yexcr.2018.06.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 06/23/2018] [Accepted: 06/27/2018] [Indexed: 12/15/2022]
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10
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Bhattarai KR, Junjappa R, Handigund M, Kim HR, Chae HJ. The imprint of salivary secretion in autoimmune disorders and related pathological conditions. Autoimmun Rev 2018; 17:376-390. [DOI: 10.1016/j.autrev.2017.11.031] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 11/16/2017] [Indexed: 12/11/2022]
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Yamamura H, Kawasaki K, Inagaki S, Suzuki Y, Imaizumi Y. Local Ca 2+ coupling between mitochondria and sarcoplasmic reticulum following depolarization in guinea pig urinary bladder smooth muscle cells. Am J Physiol Cell Physiol 2017; 314:C88-C98. [PMID: 29046294 DOI: 10.1152/ajpcell.00208.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Spatiotemporal changes in cytosolic Ca2+ concentration ([Ca2+]c) trigger a number of physiological functions in smooth muscle cells (SMCs). We previously imaged Ca2+-induced Ca2+ release following membrane depolarization as local Ca2+ transients, Ca2+ hotspots, in subplasmalemmal regions. In this study, the physiological significance of mitochondria on local Ca2+ signaling was examined. Cytosolic and mitochondrial Ca2+ images following depolarization or action potentials were recorded in single SMCs from the guinea pig urinary bladder using a fast-scanning confocal fluorescent microscope. Depolarization- and action potential-induced [Ca2+]c transients occurred at several discrete sites in subplasmalemmal regions, peaked within 30 ms, and then spread throughout the whole-cell. In contrast, Ca2+ concentration in the mitochondria matrix ([Ca2+]m) increased after a delay of ~50 ms from the start of depolarization, and then peaked within 500 ms. Following repolarization, [Ca2+]c returned to the resting level with a half-decay time of ~500 ms, while [Ca2+]m recovered more slowly (∼1.5 s). Carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone, a mitochondrial uncoupler, abolished depolarization-induced [Ca2+]m elevations and slowed [Ca2+]c changes. Importantly, short depolarization-induced changes in [Ca2+]m and transmembrane potential in mitochondria coupled to Ca2+ hotspots were significantly larger than those in other mitochondria. Total internal reflection fluorescence imaging revealed that a subset of mitochondria closely localized with ryanodine receptors and voltage-dependent Ca2+ channels. These results indicate that particular mitochondria are functionally coupled to ion channels and sarcoplasmic reticulum fragments within the local Ca2+ microdomain, and thus, strongly contribute to [Ca2+]c regulation in SMCs.
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Affiliation(s)
- Hisao Yamamura
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya , Japan
| | - Keisuke Kawasaki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya , Japan
| | - Sou Inagaki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya , Japan
| | - Yoshiaki Suzuki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya , Japan
| | - Yuji Imaizumi
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya , Japan
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Naia L, Ferreira IL, Ferreiro E, Rego AC. Mitochondrial Ca 2+ handling in Huntington's and Alzheimer's diseases - Role of ER-mitochondria crosstalk. Biochem Biophys Res Commun 2016; 483:1069-1077. [PMID: 27485547 DOI: 10.1016/j.bbrc.2016.07.122] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 07/26/2016] [Accepted: 07/29/2016] [Indexed: 10/21/2022]
Abstract
Mitochondria play a relevant role in Ca2+ buffering, governing energy metabolism and neuronal function. Huntington's disease (HD) and Alzheimer's disease (AD) are two neurodegenerative disorders that, although clinically distinct, share pathological features linked to selective brain damage. These include mitochondrial dysfunction, intracellular Ca2+ deregulation and mitochondrial Ca2+ handling deficits. Both diseases are associated with misfolding and aggregation of specific proteins that physically interact with mitochondria and interfere with endoplasmic reticulum (ER)/mitochondria-contact sites. Cumulating evidences indicate that impairment of mitochondrial Ca2+ homeostasis underlies the susceptibility to selective neuronal death observed in HD and AD; however data obtained with different models and experimental approaches are not always consistent. In this review, we explore the recent literature on deregulation of mitochondrial Ca2+ handling underlying the interplay between mitochondria and ER in HD and AD-associated neurodegeneration.
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Affiliation(s)
- Luana Naia
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; FMUC-Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Ildete Luísa Ferreira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; IIIUC-Institute for Interdisciplinary Research, University of Coimbra (IIIUC), Polo II, Coimbra, Portugal
| | - Elisabete Ferreiro
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; IIIUC-Institute for Interdisciplinary Research, University of Coimbra (IIIUC), Polo II, Coimbra, Portugal
| | - A Cristina Rego
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; FMUC-Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
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Medler KF. Calcium signaling in taste cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:2025-32. [PMID: 25450977 DOI: 10.1016/j.bbamcr.2014.11.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 10/21/2014] [Accepted: 11/07/2014] [Indexed: 11/19/2022]
Abstract
The sense of taste is a common ability shared by all organisms and is used to detect nutrients as well as potentially harmful compounds. Thus taste is critical to survival. Despite its importance, surprisingly little is known about the mechanisms generating and regulating responses to taste stimuli. All taste responses depend on calcium signals to generate appropriate responses which are relayed to the brain. Some taste cells have conventional synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release to formulate an output signal through a hemichannel. Beyond establishing these characteristics, few studies have focused on understanding how these calcium signals are formed. We identified multiple calcium clearance mechanisms that regulate calcium levels in taste cells as well as a calcium influx that contributes to maintaining appropriate calcium homeostasis in these cells. Multiple factors regulate the evoked taste signals with varying roles in different cell populations. Clearly, calcium signaling is a dynamic process in taste cells and is more complex than has previously been appreciated. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.
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Affiliation(s)
- Kathryn F Medler
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
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14
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Zheng Y, Cretoiu D, Yan G, Cretoiu SM, Popescu LM, Wang X. Comparative proteomic analysis of human lung telocytes with fibroblasts. J Cell Mol Med 2014; 18:568-89. [PMID: 24674459 PMCID: PMC4000110 DOI: 10.1111/jcmm.12290] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 01/24/2014] [Indexed: 12/22/2022] Open
Abstract
Telocytes (TCs) were recently described as interstitial cells with very long prolongations named telopodes (Tps; http://www.telocytes.com). Establishing the TC proteome is a priority to show that TCs are a distinct type of cells. Therefore, we examined the molecular aspects of lung TCs by comparison with fibroblasts (FBs). Proteins extracted from primary cultures of these cells were analysed by automated 2-dimensional nano-electrospray ionization liquid chromatography tandem mass spectrometry (2D Nano-ESI LC-MS/MS). Differentially expressed proteins were screened by two-sample t-test (P < 0.05) and fold change (>2), based on the bioinformatics analysis. We identified hundreds of proteins up- or down-regulated, respectively, in TCs as compared with FBs. TC proteins with known identities are localized in the cytoskeleton (87%) and plasma membrane (13%), while FB up-regulated proteins are in the cytoskeleton (75%) and destined to extracellular matrix (25%). These identified proteins were classified into different categories based on their molecular functions and biological processes. While the proteins identified in TCs are mainly involved in catalytic activity (43%) and as structural molecular activity (25%), the proteins in FBs are involved in catalytic activity (24%) and in structural molecular activity, particularly synthesis of collagen and other extracellular matrix components (25%). Anyway, our data show that TCs are completely different from FBs. In conclusion, we report here the first extensive identification of proteins from TCs using a quantitative proteomics approach. Protein expression profile shows many up-regulated proteins e.g. myosin-14, periplakin, suggesting that TCs might play specific roles in mechanical sensing and mechanochemical conversion task, tissue homoeostasis and remodelling/renewal. Furthermore, up-regulated proteins matching those found in extracellular vesicles emphasize TCs roles in intercellular signalling and stem cell niche modulation. The novel proteins identified in TCs will be an important resource for further proteomic research and it will possibly allow biomarker identification for TCs. It also creates the premises for understanding the pathogenesis of some lung diseases involving TCs.
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Affiliation(s)
- Yonghua Zheng
- Department of Respirology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Aravamudan B, Thompson MA, Pabelick CM, Prakash YS. Mitochondria in lung diseases. Expert Rev Respir Med 2013; 7:631-46. [PMID: 23978003 DOI: 10.1586/17476348.2013.834252] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mitochondria are autonomous cellular organelles that oversee a variety of functions such as metabolism, energy production, calcium buffering and cell fate determination. Regulation of their morphology and diverse activities beyond energy production are being recognized as playing major roles in cellular health and dysfunction. This review is aimed at summarizing what is known regarding mitochondrial contributions to pathogenesis of lung diseases. Emphasis is given to understanding the importance of structural and functional aspects of mitochondria in both normal cellular function (based on knowledge from other cell types) and in development and modulation of lung diseases such as asthma, chronic obstructive pulmonary disease, cystic fibrosis and cancer. Emerging techniques that allow examination of mitochondria, and potential strategies to target mitochondria in the treatment of lung diseases are also discussed.
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Affiliation(s)
- Bharathi Aravamudan
- Departments of Anesthesiology, Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905 USA
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16
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Schon EA, Area-Gomez E. Mitochondria-associated ER membranes in Alzheimer disease. Mol Cell Neurosci 2013; 55:26-36. [DOI: 10.1016/j.mcn.2012.07.011] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 07/26/2012] [Accepted: 07/27/2012] [Indexed: 01/03/2023] Open
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17
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Bravo R, Parra V, Gatica D, Rodriguez AE, Torrealba N, Paredes F, Wang ZV, Zorzano A, Hill JA, Jaimovich E, Quest AFG, Lavandero S. Endoplasmic reticulum and the unfolded protein response: dynamics and metabolic integration. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 301:215-90. [PMID: 23317820 DOI: 10.1016/b978-0-12-407704-1.00005-1] [Citation(s) in RCA: 418] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The endoplasmic reticulum (ER) is a dynamic intracellular organelle with multiple functions essential for cellular homeostasis, development, and stress responsiveness. In response to cellular stress, a well-established signaling cascade, the unfolded protein response (UPR), is activated. This intricate mechanism is an important means of re-establishing cellular homeostasis and alleviating the inciting stress. Now, emerging evidence has demonstrated that the UPR influences cellular metabolism through diverse mechanisms, including calcium and lipid transfer, raising the prospect of involvement of these processes in the pathogenesis of disease, including neurodegeneration, cancer, diabetes mellitus and cardiovascular disease. Here, we review the distinct functions of the ER and UPR from a metabolic point of view, highlighting their association with prevalent pathologies.
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Affiliation(s)
- Roberto Bravo
- Center for Molecular Studies of the Cell, University of Chile, Santiago, Chile
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18
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Kopach O, Vats J, Netsyk O, Voitenko N, Irving A, Fedirko N. Cannabinoid receptors in submandibular acinar cells: functional coupling between saliva fluid and electrolytes secretion and Ca2+ signalling. J Cell Sci 2012; 125:1884-95. [PMID: 22366450 DOI: 10.1242/jcs.088930] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cannabinoid receptors (CBRs) belong to the G protein-coupled receptor superfamily, and activation of CBRs in salivary cells inhibits agonist-stimulated salivation and modifies saliva content. However, the role of different CBR subtypes in acinar cell physiology and in intracellular signalling remains unclear. Here, we uncover functional CB(1)Rs and CB(2)Rs in acinar cells of rat submandibular gland and their essential role in saliva secretion. Pharmacological activation of CB(1)Rs and CB(2)Rs in the submandibular gland suppressed saliva outflow and modified saliva content produced by the submandibular gland in vivo. Using Na(+)-selective microelectrodes to record secretory Na(+) responses in the lumen of acini, we observed a reduction in Na(+) transport following the activation of CBRs, which was counteracted by the selective CB(1)R antagonist AM251. In addition, activation of CB(1)Rs or CB Rs caused inhibition of Na(+)-K(+) 2 -ATPase activity in microsomes derived from the gland tissue as well as in isolated acinar cells. Using a Ca(2+) imaging technique, we showed that activation of CB(1)Rs and CB(2)Rs alters [Ca(2+)](cyt) signalling in acinar cells by distinct pathways, involving Ca(2+) release from the endoplasmic reticulum (ER) and store-operated Ca(2+) entry (SOCE), respectively. Our data demonstrate the expression of CB(1)Rs and CB(2)Rs in acinar cells, and their involvement in the regulation of salivary gland functioning.
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Affiliation(s)
- Olga Kopach
- State Key Laboratory of Molecular and Cellular Biology, Bogomoletz Institute of Physiology, Kiev 01024, Ukraine
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Mitochondria adjust Ca2+ signaling regime to a pattern of stimulation in salivary acinar cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1740-8. [DOI: 10.1016/j.bbamcr.2011.03.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 02/27/2011] [Accepted: 03/23/2011] [Indexed: 11/19/2022]
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Fujimoto M, Hayashi T. New Insights into the Role of Mitochondria-Associated Endoplasmic Reticulum Membrane. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 292:73-117. [DOI: 10.1016/b978-0-12-386033-0.00002-5] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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21
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Fernyhough P, Calcutt NA. Abnormal calcium homeostasis in peripheral neuropathies. Cell Calcium 2009; 47:130-9. [PMID: 20034667 DOI: 10.1016/j.ceca.2009.11.008] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 11/17/2009] [Indexed: 01/02/2023]
Abstract
Abnormal neuronal calcium (Ca2+) homeostasis has been implicated in numerous diseases of the nervous system. The pathogenesis of two increasingly common disorders of the peripheral nervous system, namely neuropathic pain and diabetic polyneuropathy, has been associated with aberrant Ca2+ channel expression and function. Here we review the current state of knowledge regarding the role of Ca2+ dyshomeostasis and associated mitochondrial dysfunction in painful and diabetic neuropathies. The central impact of both alterations of Ca2+ signalling at the plasma membrane and also intracellular Ca2+ handling on sensory neurone function is discussed and related to abnormal endoplasmic reticulum performance. We also present new data highlighting sub-optimal axonal Ca2+ signalling in diabetic neuropathy and discuss the putative role for this abnormality in the induction of axonal degeneration in peripheral neuropathies. The accumulating evidence implicating Ca2+ dysregulation in both painful and degenerative neuropathies, along with recent advances in understanding of regional variations in Ca2+ channel and pump structures, makes modulation of neuronal Ca2+ handling an increasingly viable approach for therapeutic interventions against the painful and degenerative aspects of many peripheral neuropathies.
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Affiliation(s)
- Paul Fernyhough
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada R3E0T6.
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Wu PC, Fann MJ, Kao LS. Characterization of Ca2+ signaling pathways in mouse adrenal medullary chromaffin cells. J Neurochem 2009; 112:1210-22. [PMID: 20002295 DOI: 10.1111/j.1471-4159.2009.06533.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In the present study, we characterized the Ca2+ responses and secretions induced by various secretagogues in mouse chromaffin cells. Activation of the acetylcholine receptor (AChR) by carbachol induced a transient intracellular Ca2+ concentration ([Ca2+](i)) increase followed by two phases of [Ca2+](i) decay and a burst of exocytic events. The contribution of the subtypes of AChRs to carbachol-induced responses was examined. Based on the results obtained by stimulating the cells with the nicotinic receptor (nAChR) agonist, 1,1-dimethyl-4-phenylpiperazinium iodide, high K(+) and the effects of thapsigargin, it appears that activation of nAChRs induces an extracellular Ca2+ influx, which in turn activate Ca(2+)-induced Ca2+ release via the ryanodine receptors. Muscarine, a muscarinic receptor (mAChRs) agonist, was found to induce [Ca2+](i) oscillation and sustained catecholamine release, possibly by activation of both the receptor- and store-operated Ca2+ entry pathways. The RT-PCR results showed that mouse chromaffin cells are equipped with messages for multiple subtypes of AChRs, ryanodine receptors and all known components of the receptor- and store-operated Ca2+ entry. Furthermore, results obtained by directly monitoring endoplasmic reticulum (ER) and mitochondrial Ca2+ concentration and by disabling mitochondrial Ca2+ uptake suggest that the ER acts as a Ca2+ source, while the mitochondria acts as a Ca2+ sink. Our results show that both nAChRs and mAChRs contribute to the initial carbachol-induced [Ca2+](i) increase which is further enhanced by the Ca2+ released from the ER mediated by Ca(2+)-induced Ca2+ release and mAChR activation. This information on the Ca2+ signaling pathways should lay a good foundation for future studies using mouse chromaffin cells as a model system.
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Affiliation(s)
- Pei-Chun Wu
- Molecular Medicine Program, National Yang-Ming University, Taipei, Taiwan
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23
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Gunter TE, Sheu SS. Characteristics and possible functions of mitochondrial Ca(2+) transport mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1787:1291-308. [PMID: 19161975 PMCID: PMC2730425 DOI: 10.1016/j.bbabio.2008.12.011] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 12/22/2008] [Accepted: 12/29/2008] [Indexed: 02/07/2023]
Abstract
Mitochondria produce around 92% of the ATP used in the typical animal cell by oxidative phosphorylation using energy from their electrochemical proton gradient. Intramitochondrial free Ca(2+) concentration ([Ca(2+)](m)) has been found to be an important component of control of the rate of this ATP production. In addition, [Ca(2+)](m) also controls the opening of a large pore in the inner mitochondrial membrane, the permeability transition pore (PTP), which plays a role in mitochondrial control of programmed cell death or apoptosis. Therefore, [Ca(2+)](m) can control whether the cell has sufficient ATP to fulfill its functions and survive or is condemned to death. Ca(2+) is also one of the most important second messengers within the cytosol, signaling changes in cellular response through Ca(2+) pulses or transients. Mitochondria can also sequester Ca(2+) from these transients so as to modify the shape of Ca(2+) signaling transients or control their location within the cell. All of this is controlled by the action of four or five mitochondrial Ca(2+) transport mechanisms and the PTP. The characteristics of these mechanisms of Ca(2+) transport and a discussion of how they might function are described in this paper.
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Affiliation(s)
- Thomas E Gunter
- Department of Biochemistry and Biophysics and Mitochondrial Research and Innovation Group, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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Area-Gomez E, de Groof AJC, Boldogh I, Bird TD, Gibson GE, Koehler CM, Yu WH, Duff KE, Yaffe MP, Pon LA, Schon EA. Presenilins are enriched in endoplasmic reticulum membranes associated with mitochondria. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 175:1810-6. [PMID: 19834068 DOI: 10.2353/ajpath.2009.090219] [Citation(s) in RCA: 290] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Presenilin-1 (PS1) and -2 (PS2), which when mutated cause familial Alzheimer disease, have been localized to numerous compartments of the cell, including the endoplasmic reticulum, Golgi, nuclear envelope, endosomes, lysosomes, the plasma membrane, and mitochondria. Using three complementary approaches, subcellular fractionation, gamma-secretase activity assays, and immunocytochemistry, we show that presenilins are highly enriched in a subcompartment of the endoplasmic reticulum that is associated with mitochondria and that forms a physical bridge between the two organelles, called endoplasmic reticulum-mitochondria-associated membranes. A localization of PS1 and PS2 in mitochondria-associated membranes may help reconcile the disparate hypotheses regarding the pathogenesis of Alzheimer disease and may explain many seemingly unrelated features of this devastating neurodegenerative disorder.
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Affiliation(s)
- Estela Area-Gomez
- Department of Neurology, Columbia University Medical Center, New York, New York, USA
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Laskowski AI, Medler KF. Sodium-calcium exchangers contribute to the regulation of cytosolic calcium levels in mouse taste cells. J Physiol 2009; 587:4077-89. [PMID: 19581381 DOI: 10.1113/jphysiol.2009.173567] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Taste cells use multiple signalling mechanisms to generate unique calcium responses to distinct taste stimuli. Some taste stimuli activate G-protein coupled receptors (GPCRs) that cause calcium release from intracellular stores while other stimuli depolarize taste cells to cause calcium influx through voltage-gated calcium channels (VGCCs). We recently demonstrated that a constitutive calcium influx exists in taste cells that is regulated by mitochondrial calcium transport and that the magnitude of this calcium influx correlates with the signalling mechanisms used by the taste cells. In this study, we used calcium imaging to determine that sodium-calcium exchangers (NCXs) also routinely contribute to the regulation of basal cytosolic calcium and that their relative role correlates with the signalling mechanisms used by the taste cells. RT-PCR analysis revealed that multiple NCXs and sodium-calcium-potassium exchangers (NCKXs) are expressed in taste cells. Thus, a dynamic relationship exists between calcium leak channels and calcium regulatory mechanisms in taste cells that functions to keep cytosolic calcium levels in the appropriate range for cell function.
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Affiliation(s)
- Agnieszka I Laskowski
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
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Wang J, Jiang L, Gao X, Ding H, Wang Q, Cheng J, Gao R, Xiao H. Fenvalerate-induced Ca2+ transients via both intracellular and extracellular way in mouse GC-2spd (ts) cells. Toxicology 2009; 259:122-32. [DOI: 10.1016/j.tox.2009.02.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2008] [Revised: 02/19/2009] [Accepted: 02/19/2009] [Indexed: 11/28/2022]
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Sergeant GP, Bradley E, Thornbury KD, McHale NG, Hollywood MA. Role of mitochondria in modulation of spontaneous Ca2+ waves in freshly dispersed interstitial cells of Cajal from the rabbit urethra. J Physiol 2008; 586:4631-42. [PMID: 18703577 DOI: 10.1113/jphysiol.2008.159194] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Interstitial cells of Cajal (ICC) isolated from the rabbit urethra exhibit pacemaker activity that results from spontaneous Ca(2+) waves. The purpose of this study was to investigate if this activity was influenced by Ca(2+) uptake into mitochondria. Spontaneous Ca(2+) waves were recorded using a Nipkow spinning disk confocal microscope and spontaneous transient inward currents (STICs) were recorded using the whole-cell patch clamp technique. Disruption of the mitochondrial membrane potential with the electron transport chain inhibitors rotenone (10 microm) and antimycin A (5 microm) abolished Ca(2+) waves and increased basal Ca(2+) levels. Similar results were achieved when mitochondria membrane potential was collapsed using the protonophores FCCP (0.2 microm) and CCCP (1 microm). Spontaneous Ca(2+) waves were not inhibited by the ATP synthase inhibitor oligomycin (1 microm), suggesting that these effects were not attributable to an effect on ATP levels. STICs recorded under voltage clamp at -60 mV were also inhibited by CCCP and antimycin A. Dialysis of cells with the mitochondrial uniporter inhibitor RU360 (10 microm) also inhibited STICS. Stimulation of Ca(2+) uptake into mitochondria using the plant flavonoid kaempferol (10 microm) induced a series of propagating Ca(2+) waves. The kaempferol-induced activity was inhibited by application of caffeine (10 mm) or removal of extracellular Ca(2+), but was not significantly affected by the IP(3) receptor blocker 2-APB (100 microm). These data suggest that spontaneous Ca(2+) waves in urethral ICC are regulated by buffering of cytoplasmic Ca(2+) by mitochondria.
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Affiliation(s)
- Gerard P Sergeant
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co Louth, Ireland.
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Hacker K, Medler KF. Mitochondrial calcium buffering contributes to the maintenance of Basal calcium levels in mouse taste cells. J Neurophysiol 2008; 100:2177-91. [PMID: 18684902 DOI: 10.1152/jn.90534.2008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Taste stimuli are detected by taste receptor cells present in the oral cavity using diverse signaling pathways. Some taste stimuli are detected by G protein-coupled receptors (GPCRs) that cause calcium release from intracellular stores, whereas other stimuli depolarize taste cells to cause calcium influx through voltage-gated calcium channels (VGCCs). Although taste cells use two distinct mechanisms to transmit taste signals, increases in cytosolic calcium are critical for normal responses in both pathways. This creates a need to tightly control intracellular calcium levels in all transducing taste cells. To date, however, the mechanisms used by taste cells to regulate cytosolic calcium levels have not been identified. Studies in other cell types have shown that mitochondria can be important calcium buffers, even during small changes in calcium loads. In this study, we used calcium imaging to characterize the role of mitochondria in buffering calcium levels in taste cells. We discovered that mitochondria make important contributions to the maintenance of resting calcium levels in taste cells by routinely buffering a constitutive calcium influx across the plasma membrane. This is unusual because in other cell types, mitochondrial calcium buffering primarily affects large evoked calcium responses. We also found that the amount of calcium that is buffered by mitochondria varies with the signaling pathways used by the taste cells. A transient receptor potential (TRP) channel, likely TRPV1 or a taste variant of TRPV1, contributes to the constitutive calcium influx.
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Affiliation(s)
- Kyle Hacker
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
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