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Sun CC, Lee SY, Chen LH, Lai CH, Shen ZQ, Chen NN, Lai YS, Tung CY, Tzeng TY, Chiu WT, Tsai TF. Targeting Ca 2+-dependent pathways to promote corneal epithelial wound healing induced by CISD2 deficiency. Cell Signal 2023:110755. [PMID: 37315750 DOI: 10.1016/j.cellsig.2023.110755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/25/2023] [Accepted: 06/06/2023] [Indexed: 06/16/2023]
Abstract
Chronic epithelial defects of the cornea, which are usually associated with severe dry eye disease, diabetes mellitus, chemical injuries or neurotrophic keratitis, as well as aging, are an unmet clinical need. CDGSH Iron Sulfur Domain 2 (CISD2) is the causative gene for Wolfram syndrome 2 (WFS2; MIM 604928). CISD2 protein is significantly decreased in the corneal epithelium of patients with various corneal epithelial diseases. Here we summarize the most updated publications and discuss the central role of CISD2 in corneal repair, as well as providing new results describing how targeting Ca2+-dependent pathways can improve corneal epithelial regeneration. This review mainly focuses on the following topics. Firstly, an overview of the cornea and of corneal epithelial wound healing. The key players involved in this process, such as Ca2+, various growth factors/cytokines, extracellular matrix remodeling, focal adhesions and proteinases, are briefly discussed. Secondly, it is well known that CISD2 plays an essential role in corneal epithelial regeneration via the maintenance of intracellular Ca2+ homeostasis. CISD2 deficiency dysregulates cytosolic Ca2+, impairs cell proliferation and migration, decreases mitochondrial function and increases oxidative stress. As a consequence, these abnormalities bring about poor epithelial wound healing and this, in turn, will lead to persistent corneal regeneration and limbal progenitor cell exhaustion. Thirdly, CISD2 deficiency induces three distinct Ca2+-dependent pathways, namely the calcineurin, CaMKII and PKCα signaling pathways. Intriguingly, inhibition of each of the Ca2+-dependent pathways seems to reverse cytosolic Ca2+ dysregulation and restore cell migration during corneal wound healing. Notably, cyclosporin, an inhibitor of calcineurin, appears to have a dual effect on both inflammatory and corneal epithelial cells. Finally, corneal transcriptomic analyses have revealed that there are six major functional groupings of differential expression genes when CISD2 deficiency is present: (1) inflammation and cell death; (2) cell proliferation, migration and differentiation; (3) cell adhesion, junction and interaction; (4) Ca2+ homeostasis; (5) wound healing and extracellular matrix; and (6) oxidative stress and aging. This review highlights the importance of CISD2 in corneal epithelial regeneration and identifies the potential of repurposing venerable FDA-approved drugs that target Ca2+-dependent pathways for new uses, namely treating chronic epithelial defects of the cornea.
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Affiliation(s)
- Chi-Chin Sun
- Department of Ophthalmology, Chang Gung Memorial Hospital, Keelung 204, Taiwan; School of Medicine, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan
| | - Shao-Yun Lee
- Department of Ophthalmology, Chang Gung Memorial Hospital, Keelung 204, Taiwan
| | - Li-Hsien Chen
- Department of Pharmacology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Chia-Hui Lai
- Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan 333, Taiwan
| | - Zhao-Qing Shen
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Nan-Ni Chen
- Department of Ophthalmology, Chang Gung Memorial Hospital, Chiayi 613, Taiwan
| | - Yi-Shyun Lai
- Department of Biomedical Engineering, College of Engineering, National Cheng Kung University, Tainan 701, Taiwan
| | - Chien-Yi Tung
- Genomics Center for Clinical and Biotechnological Applications, Cancer Progression Research Center, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Tsai-Yu Tzeng
- Genomics Center for Clinical and Biotechnological Applications, Cancer Progression Research Center, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Wen-Tai Chiu
- Department of Biomedical Engineering, College of Engineering, National Cheng Kung University, Tainan 701, Taiwan.
| | - Ting-Fen Tsai
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan; Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli 350, Taiwan; Center for Healthy Longevity and Aging Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.
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Collins HE, Anderson JC, Wende AR, Chatham JC. Cardiomyocyte stromal interaction molecule 1 is a key regulator of Ca 2+ -dependent kinase and phosphatase activity in the mouse heart. Physiol Rep 2022; 10:e15177. [PMID: 35179826 PMCID: PMC8855923 DOI: 10.14814/phy2.15177] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/04/2022] [Accepted: 01/07/2022] [Indexed: 04/26/2023] Open
Abstract
Stromal interaction molecule 1 (STIM1) is a major regulator of store-operated calcium entry in non-excitable cells. Recent studies have suggested that STIM1 plays a role in pathological hypertrophy; however, the physiological role of STIM1 in the heart is not well understood. We have shown that mice with a cardiomyocyte deletion of STIM1 (cr STIM1-/- ) develop ER stress, mitochondrial, and metabolic abnormalities, and dilated cardiomyopathy. However, the specific signaling pathways and kinases regulated by STIM1 are largely unknown. Therefore, we used a discovery-based kinomics approach to identify kinases differentially regulated by STIM1. Twelve-week male control and cr STIM1-/- mice were injected with saline or phenylephrine (PE, 15 mg/kg, s.c, 15 min), and hearts obtained for analysis of the Serine/threonine kinome. Primary analysis was performed using BioNavigator 6.0 (PamGene), using scoring from the Kinexus PhosphoNET database and GeneGo network modeling, and confirmed using standard immunoblotting. Kinomics revealed significantly lower PKG and protein kinase C (PKC) signaling in the hearts of the cr STIM1-/- in comparison to control hearts, confirmed by immunoblotting for the calcium-dependent PKC isoform PKCα and its downstream target MARCKS. Similar reductions in cr STIM1-/- hearts were found for the kinases: MEK1/2, AMPK, and PDPK1, and in the activity of the Ca2+ -dependent phosphatase, calcineurin. Electrocardiogram analysis also revealed that cr STIM1-/- mice have significantly lower HR and prolonged QT interval. In conclusion, we have shown several calcium-dependent kinases and phosphatases are regulated by STIM1 in the adult mouse heart. This has important implications in understanding how STIM1 contributes to the regulation of cardiac physiology and pathophysiology.
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Affiliation(s)
- Helen E. Collins
- Division of Environmental MedicineDepartment of MedicineUniversity of LouisvilleLouisvilleKentuckyUSA
| | - Joshua C. Anderson
- Department of Radiation OncologyUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Adam R. Wende
- Division of Molecular and Cellular PathologyDepartment of PathologyUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - John C. Chatham
- Division of Molecular and Cellular PathologyDepartment of PathologyUniversity of Alabama at BirminghamBirminghamAlabamaUSA
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3
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Hypoxia-activated platelets stimulate proliferation and migration of pulmonary arterial smooth muscle cells by phosphatidylserine/LOX-1 signaling-impelled intercellular communication. Cell Signal 2021; 87:110149. [PMID: 34520855 DOI: 10.1016/j.cellsig.2021.110149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 08/23/2021] [Accepted: 09/09/2021] [Indexed: 11/20/2022]
Abstract
Continuous recruitment and inappropriate activation of platelets in pulmonary arteries contribute to pulmonary vascular remodeling in pulmonary hypertension (PH). Our previous study has demonstrated that lectin like oxidized low-density lipoprotein receptor-1 (LOX-1) regulates the proliferation of pulmonary arterial smooth muscle cells (PASMCs). Phosphatidylserine exposed on the surface of activated platelets is a ligand for LOX-1. However, whether hypoxia-activated platelets stimulate the proliferation and migration of PASMCs by phosphatidylserine/LOX-1 signaling-impelled intercellular communication remains unclear. The present study found that rats treated with hypoxia (10% O2) for 21 days revealed PH with the activation of platelets and the recruitment of platelets in pulmonary arteries, and LOX-1 knockout inhibited hypoxia-induced PH and platelets activation. Notably, co-incubation of PASMCs with hypoxic PH rats-derived platelets up-regulated LOX-1 expression in PASMCs leading to the proliferation and migration of PASMCs, which was inhibited by the phosphatidylserine inhibitor annexin V or the LOX-1 neutralizing antibody. LOX-1 knockout led to decreased proliferation and migration of PASMCs stimulated by hypoxia-activated platelets. In rats, hypoxia up-regulated the phosphorylation of signal transducer and activator of transcription 3 (Stat3) and the expression of Pim-1 in pulmonary arteries. Hypoxia-activated platelets also up-regulated the phosphorylation of Stat3 and the expression of Pim-1 in PASMCs, which was inhibited by annexin V, the LOX-1 neutralizing antibody, the protein kinase C inhibitor and LOX-1 knockout. In conclusion, we for the first time demonstrated that hypoxia-activated platelets stimulated the proliferation and migration of PASMCs by phosphatidylserine/LOX-1/PKC/Stat3/Pim-1 signaling-impelled intercellular communication, thereby potentially contributing to hypoxic pulmonary vascular remodeling.
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Wang YM, Xu WJ, Xiang LL, Ding M, Zhang JJ, Lu JY, Xie BJ, Gao YD. Store-operated Calcium Entry-associated Regulatory Factor Regulates Airway Inflammation and Airway Remodeling in Asthma Mice Models. Am J Physiol Lung Cell Mol Physiol 2021; 321:L533-L544. [PMID: 34231388 DOI: 10.1152/ajplung.00079.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Store-operated calcium entry (SOCE) is involved in the pathogenesis of airway inflammation and remodeling in asthma. Store-operated calcium entry-associated regulatory factor (SARAF) can down-regulate SOCE. OBJECTIVE We sought to investigate the role of SARAF in the regulation of airway inflammation and remodeling in asthma mice models, as well as in the functional regulation of human airway smooth muscle cells (hASMCs). METHODS Balb/c mice were sensitized and challenged with ovalbumin to establish the asthma mice models. Mice were transfected with lentivirus, which expressed the SARAF gene + GFP or the negative control gene + GFP. Airway resistance was measured with the animal pulmonary function system. Airway inflammation and remodeling were evaluated via histological staining. In vitro cultured hASMCs were transfected with scrambled small interfering RNA(siRNA) or SARAF-specific siRNA respecitvely. The proliferation, migration rate, hypertrophy and SOCE activity of hASMCs were examined with cell counting kit 8, wound healing test, bright field imaging and Ca2+ fluorescence imaging, respectively. SARAF expression was measured by quantitative real-time-PCR. RESULTS Asthma mice models showed decreased SARAF mRNA expression in the lungs. SARAF overexpression attenuated airway inflammation, resistance and also remodeling. Downregulation of SARAF expression with siRNA promoted the proliferation, migration, hypertrophy and SOCE activity in hASMCs. CONCLUSIONS SARAF plays a protective role against airway inflammation and remodeling in asthma mice models by blunting SOCE; SARAF may also be a functional regulating factor of hASMCs.
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Affiliation(s)
- Yi-Min Wang
- Department of Respiratory Medicine, Zhongnan Hospital of Wuhan University, China.,Department of Allergology, Zhongnan Hospital of Wuhan University, China
| | - Wen-Juan Xu
- Department of Respiratory Medicine, Zhongnan Hospital of Wuhan University, China
| | - Lin-Li Xiang
- Department of Respiratory Medicine, Zhongnan Hospital of Wuhan University, China
| | - Mei Ding
- Department of Allergology, Zhongnan Hospital of Wuhan University, China
| | - Jin-Jin Zhang
- Department of Allergology, Zhongnan Hospital of Wuhan University, China
| | - Jing-Ya Lu
- Department of Epidemiology and Biostatistics, Ministry of Education Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, China
| | - Bao-Juan Xie
- Department of Respiratory Medicine, Zhongnan Hospital of Wuhan University, China
| | - Ya-Dong Gao
- Department of Allergology, Zhongnan Hospital of Wuhan University, China
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Martín-Aragón Baudel MAS, Shi J, Large WA, Albert AP. Obligatory role for PKCδ in PIP 2 -mediated activation of store-operated TRPC1 channels in vascular smooth muscle cells. J Physiol 2020; 598:3911-3925. [PMID: 32627185 PMCID: PMC7656825 DOI: 10.1113/jp279947] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/01/2020] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS In vascular smooth muscle cells (VSMCs), activation of Ca2+ -permeable store-operated channels (SOCs) composed of canonical transient receptor potential channel 1 (TRPC1) subunits mediates Ca2+ entry pathways that regulate contraction, proliferation and migration, which are processes associated with vascular disease. Activation of TRPC1-based SOCs requires protein kinase C (PKC) activity, which is proposed to phosphorylate TRPC1 proteins to promote channel opening by phosphatidylinositol 4,5-bisphosphate (PIP2 ). We investigated the identity of the PKC isoform involved in activating TRPC1-based SOCs in rat mesenteric artery VSMCs. TRPC1-based SOCs were reduced by PKCδ inhibitors and knockdown of PKCδ expression. Store depletion induced interactions between TRPC1 and PKCδ and PKCδ-dependent phosphorylation of TRPC1. Furthermore, generation of store-operated interactions between PIP2 and TRPC1 and activation of TRPC1-based SOCs by PIP2 required PKCδ. These findings reveal that PKCδ activity has an obligatory role in activating TRPC1-based SOCs, through regulating PIP2 -mediated channel opening. ABSTRACT In vascular smooth muscle cells (VMSCs), stimulation of Ca2+ -permeable canonical transient receptor potential channel 1 (TRPC1)-based store-operated channels (SOCs) mediates Ca2+ entry pathways that regulate cell contraction, proliferation and migration, which are processes associated with vascular disease. It is therefore important to understand how TRPC1-based SOCs are activated. Stimulation of TRPC1-based SOCs requires protein kinase C (PKC) activity, with store-operated PKC-dependent phosphorylation of TRPC1 essential for channel opening by phosphatidylinositol 4,5-bisphosphate (PIP2 ). Experimental protocols used to activate TRPC1-based SOCs suggest that the PKC isoform involved requires diacylglycerol (DAG) but is Ca2+ -insensitive, which are characteristics of the novel group of PKC isoforms (δ, ε, η, θ). Hence, the present study examined whether a novel PKC isoform(s) is involved in activating TRPC1-based SOCs in contractile rat mesenteric artery VSMCs. Store-operated whole-cell cation currents were blocked by Pico145, a highly selective and potent TRPC1/4/5 channel blocker and T1E3, a TRPC1 blocking antibody. PKCδ was expressed in VSMCs, and selective PKCδ inhibitory peptides and knockdown of PKCδ expression with morpholinos oligomers inhibited TRPC1-based SOCs. TRPC1 and PKCδ interactions and phosphorylation of TRPC1 induced by store depletion were both reduced by pharmacological inhibition and PKCδ knockdown. In addition, store-operated PIP2 and TRPC1 interactions were blocked by PKCδ inhibition, and PKCδ was required for PIP2 -mediated activation of TRPC1 currents. These results identify the involvement of PKCδ in stimulation of TRPC1-based SOCs and highlight that store-operated PKCδ activity is obligatory for channel opening by PIP2 , the probable activating ligand.
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Affiliation(s)
| | - Jian Shi
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds, UK
| | - William A Large
- Vascular Biology Research Centre, Molecular and Clinical Research Institute, St George's, University of London, Cranmer Terrace, London, UK
| | - Anthony P Albert
- Vascular Biology Research Centre, Molecular and Clinical Research Institute, St George's, University of London, Cranmer Terrace, London, UK
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Baratchi S, Keov P, Darby WG, Lai A, Khoshmanesh K, Thurgood P, Vahidi P, Ejendal K, McIntyre P. The TRPV4 Agonist GSK1016790A Regulates the Membrane Expression of TRPV4 Channels. Front Pharmacol 2019; 10:6. [PMID: 30728775 PMCID: PMC6351496 DOI: 10.3389/fphar.2019.00006] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 01/04/2019] [Indexed: 02/05/2023] Open
Abstract
TRPV4 is a non-selective cation channel that tunes the function of different tissues including the vascular endothelium, lung, chondrocytes, and neurons. GSK1016790A is the selective and potent agonist of TRPV4 and a pharmacological tool that is used to study the TRPV4 physiological function in vitro and in vivo. It remains unknown how the sensitivity of TRPV4 to this agonist is regulated. The spatial and temporal dynamics of receptors are the major determinants of cellular responses to stimuli. Membrane translocation has been shown to control the response of several members of the transient receptor potential (TRP) family of ion channels to different stimuli. Here, we show that TRPV4 stimulation with GSK1016790A caused an increase in [Ca2+]i that is stable for a few minutes. Single molecule analysis of TRPV4 channels showed that the density of TRPV4 at the plasma membrane is controlled through two modes of membrane trafficking, complete, and partial vesicular fusion. Further, we show that the density of TRPV4 at the plasma membrane decreased within 20 min, as they translocate to the recycling endosomes and that the surface density is dependent on the release of calcium from the intracellular stores and is controlled via a PI3K, PKC, and RhoA signaling pathway.
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Affiliation(s)
- Sara Baratchi
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - Peter Keov
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia.,Molecular Pharmacology Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.,St Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW, Australia
| | - William G Darby
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - Austin Lai
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | | | - Peter Thurgood
- School of Engineering, RMIT University, Melbourne, VIC, Australia
| | - Parisa Vahidi
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - Karin Ejendal
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| | - Peter McIntyre
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
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Lin BH, Tsai MH, Lii CK, Wang TS. IP3 and calcium signaling involved in the reorganization of the actin cytoskeleton and cell rounding induced by cigarette smoke extract in human endothelial cells. ENVIRONMENTAL TOXICOLOGY 2016; 31:1293-1306. [PMID: 25758670 DOI: 10.1002/tox.22133] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 02/09/2015] [Accepted: 02/15/2015] [Indexed: 06/04/2023]
Abstract
Smoking increases the risk of cardiovascular disorders and leads to damage caused by inflammation and oxidative stress. The actin cytoskeleton is a key player in the response to inflammatory stimuli and is an early target of cellular oxidative stress. The purpose of this study was to investigate the changes in actin cytoskeleton dynamics in human endothelial EA.hy926 cells exposed to cigarette smoke extract (CSE). Immunostaining revealed that CSE exposure resulted in modification of the actin cytoskeleton and led to cell rounding in a dose- and time-dependent manner. In addition, the intracellular calcium concentration was increased by treatment with CSE. Pretreatment with antioxidants (lipoic acid, glutathione, N-acetyl cysteine, aminoguanidine, α-tocopherol, and vitamin C) significantly attenuated the CSE-induced actin cytoskeleton reorganization and cell rounding. Calcium ion chelators (EGTA, BAPTA-AM AM) and a potent store-operated calcium channel inhibitor (MRS 1845) also reduced CSE-induced intracellular calcium changes and attenuated actin cytoskeleton reorganization and cell morphology change. Moreover, the CSE-induced intracellular calcium increase was suppressed by pretreatment with the inositol trisphosphate receptor (IP3R) inhibitor xestospongin C, the phospholipase C (PLC) inhibitor U-73122, and the protein kinase C (PKC) inhibitor GF109203X. These results suggest that reactive oxygen species production and intracellular calcium increase play an essential role in CSE-induced actin disorganization and cell rounding through a PLC-IP3-PKC signaling pathway. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1293-1306, 2016.
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Affiliation(s)
- Bo-Hong Lin
- School of Biomedical Sciences, Chung Shan Medical University, Taichung, Taiwan
| | - Ming-Hsuan Tsai
- School of Biomedical Sciences, Chung Shan Medical University, Taichung, Taiwan
| | - Chong-Kuei Lii
- Department of Nutrition, China Medical University, Taichung, Taiwan
- Department of Health and Nutrition Biotechnology, Asia University, Taichung, Taiwan
| | - Tsu-Shing Wang
- School of Biomedical Sciences, Chung Shan Medical University, Taichung, Taiwan.
- Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan.
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Plasma membrane Ca2+-ATPase regulates Ca2+ signaling and the proliferation of airway smooth muscle cells. Eur J Pharmacol 2014; 740:733-41. [PMID: 24912144 DOI: 10.1016/j.ejphar.2014.05.055] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/25/2014] [Accepted: 05/27/2014] [Indexed: 01/03/2023]
Abstract
Plasma membrane Ca2+-ATPase (PMCA) plays an important role in regulating intracellular Ca2+ homeostasis by extruding excessive Ca2+ to extracellular spaces. PMCA has four isoforms and is widely expressed in different tissues and cells including airway smooth muscle cells (ASMCs). In the present study, we investigated the role of PMCA in the maintenance of Ca2+ homeostasis and regulation of ASMCs proliferation. By using Ca2+ fluorescence, we found that inhibition of PMCA with LaCl3 or carboxyeosin (CE) decreased the decay rate of Ca2+ transient induced by bradykinin (BK). No obvious decay was observed when SERCA was inhibited by thapsigargin (TpG). LaCl3 and CE also induced a spontaneous [Ca2+]i increase in the presence of TpG even in Ca2+-free bath solution. Both LaCl3 and CE inhibited UTP-induced Ca2+ oscillations in ASMCs. PCR assay found that PMCA1 and PMCA4 mRNA were expressed in rat ASMCs. The expression of PMCA4 was downregulated in proliferating ASMCs when compared to resting cells. Both the isoform-nonselective PMCA inhibitor caloxin 2a1 and PMCA4-selective inhibitor caloxin 1b1 decreased the decay rate of Ca2+ transient induced by TpG or BK. PMCA inhibitors except caloxin 2a1 promoted ASMCs proliferation. Annexin-V apoptosis assay detected that caloxin 2a1 increased ASMCs apoptosis, suggesting that inhibition of PMCA with different blockers results in different [Ca2+]i and thus different cellular response. Our results provide evidences to support the hypothesis that PMCA is involved in the regulation of Ca2+ homeostasis and ASMCs proliferation. These data suggest that PMCA may be a new target in the treatment of chronic asthma.
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