1
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González-Burguera I, Lin G, López de Jesús M, Saumell-Esnaola M, Barrondo S, García Del Caño G, Sallés J, Scarlata S. PLCβ1 by-passes early growth response -1 to induce the differentiation of neuronal cells. Cell Death Discov 2024; 10:250. [PMID: 38789419 PMCID: PMC11126630 DOI: 10.1038/s41420-024-02009-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 04/30/2024] [Accepted: 05/07/2024] [Indexed: 05/26/2024] Open
Abstract
The Gαq/phospholipase C-β (PLCβ) signaling system mediates calcium responses to a variety of hormones and neurotransmitters. Recent studies suggest that PLCβ1 expression plays a role in the differentiation of two types of cultured neuronal cells (PC12 and SK-N-SH) through a mechanism independent of Gαq. Here, we show that, similar to that observed in PC12 and SK-N-SH cells, PLCβ1 expression increases when human NT2 cells are induced to differentiate either through cytosine-β-D-arabinofuranoside or retinoic acid. Preventing this increase, abolishes differentiation, and down-regulating PLCβ1 in rat primary astrocytes causes cells to adapt an undifferentiated morphology. Surprisingly, transfecting PLCβ1 into undifferentiated PC12 or NT2 cells induces differentiation without the need for differentiating agents. Studies to uncover the underlying mechanism focused on the transcription factor early growth response 1 (Egr-1) which mediates PLCβ1 expression early in differentiation. Over-expressing PLCβ1 in HEK293 cells enhances Egr-1 expression and induces morphological changes. We show that increased levels of cytosolic PLCβ1 in undifferentiated PC12 cells disrupts the association between Egr-1 and its cytosolic binding partner (Tar RNA binding protein), promoting relocalization of Egr-1 to the nucleus, which promotes transcription of proteins needed for differentiation. These studies show a novel mechanism through which differentiation can be modulated.
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Affiliation(s)
- Imanol González-Burguera
- Department of Neurosciences, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006, Vitoria-Gasteiz, Spain
- Bioaraba, Neurofarmacología Celular y Molecular, 01006, Vitoria-Gasteiz, Spain
| | - Guanyu Lin
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, 01609, USA
| | - Maider López de Jesús
- Bioaraba, Neurofarmacología Celular y Molecular, 01006, Vitoria-Gasteiz, Spain
- Department of Pharmacology, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006, Vitoria-Gasteiz, Spain
| | - Miquel Saumell-Esnaola
- Bioaraba, Neurofarmacología Celular y Molecular, 01006, Vitoria-Gasteiz, Spain
- Department of Pharmacology, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006, Vitoria-Gasteiz, Spain
| | - Sergio Barrondo
- Bioaraba, Neurofarmacología Celular y Molecular, 01006, Vitoria-Gasteiz, Spain
- Department of Pharmacology, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006, Vitoria-Gasteiz, Spain
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), 28029, Madrid, Spain
| | - Gontzal García Del Caño
- Department of Neurosciences, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006, Vitoria-Gasteiz, Spain
- Bioaraba, Neurofarmacología Celular y Molecular, 01006, Vitoria-Gasteiz, Spain
| | - Joan Sallés
- Bioaraba, Neurofarmacología Celular y Molecular, 01006, Vitoria-Gasteiz, Spain
- Department of Pharmacology, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006, Vitoria-Gasteiz, Spain
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), 28029, Madrid, Spain
| | - Suzanne Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, 01609, USA.
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2
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Fazio A, Evangelisti C, Cappellini A, Mongiorgi S, Koufi FD, Neri I, Marvi MV, Russo M, Ghigo A, Manzoli L, Fiume R, Ratti S. Emerging Roles of Phospholipase C Beta Isozymes as Potential Biomarkers in Cardiac Disorders. Int J Mol Sci 2023; 24:13096. [PMID: 37685903 PMCID: PMC10487445 DOI: 10.3390/ijms241713096] [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: 08/03/2023] [Revised: 08/19/2023] [Accepted: 08/21/2023] [Indexed: 09/10/2023] Open
Abstract
Phospholipase C (PLC) enzymes represent crucial participants in the plasma membrane of mammalian cells, including the cardiac sarcolemmal (SL) membrane of cardiomyocytes. They are responsible for the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) into 1,2-diacylglycerol (DAG) and inositol (1,4,5) trisphosphate (Ins(1,4,5)P3), both essential lipid mediators. These second messengers regulate the intracellular calcium (Ca2+) concentration, which activates signal transduction cascades involved in the regulation of cardiomyocyte activity. Of note, emerging evidence suggests that changes in cardiomyocytes' phospholipid profiles are associated with an increased occurrence of cardiovascular diseases, but the underlying mechanisms are still poorly understood. This review aims to provide a comprehensive overview of the significant impact of PLC on the cardiovascular system, encompassing both physiological and pathological conditions. Specifically, it focuses on the relevance of PLCβ isoforms as potential cardiac biomarkers, due to their implications for pathological disorders, such as cardiac hypertrophy, diabetic cardiomyopathy, and myocardial ischemia/reperfusion injury. Gaining a deeper understanding of the mechanisms underlying PLCβ activation and regulation is crucial for unraveling the complex signaling networks involved in healthy and diseased myocardium. Ultimately, this knowledge holds significant promise for advancing the development of potential therapeutic strategies that can effectively target and address cardiac disorders by focusing on the PLCβ subfamily.
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Affiliation(s)
- Antonietta Fazio
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Camilla Evangelisti
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Alessandra Cappellini
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Sara Mongiorgi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Foteini-Dionysia Koufi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Irene Neri
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Maria Vittoria Marvi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Michele Russo
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center “Guido Tarone”, University of Torino, 10126 Torino, Italy; (M.R.); (A.G.)
| | - Alessandra Ghigo
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center “Guido Tarone”, University of Torino, 10126 Torino, Italy; (M.R.); (A.G.)
| | - Lucia Manzoli
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Roberta Fiume
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Stefano Ratti
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
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Kim Y, Ko TH, Jin C, Zhang Y, Kang HR, Ma R, Li H, Choi JI, Han K. The emerging roles of Shank3 in cardiac function and dysfunction. Front Cell Dev Biol 2023; 11:1191369. [PMID: 37187620 PMCID: PMC10175600 DOI: 10.3389/fcell.2023.1191369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 04/17/2023] [Indexed: 05/17/2023] Open
Abstract
Shank3 is a member of the Shank family proteins (Shank1-3), which are abundantly present in the postsynaptic density (PSD) of neuronal excitatory synapses. As a core scaffold in the PSD, Shank3 plays a critical role in organizing the macromolecular complex, ensuring proper synaptic development and function. Clinically, various mutations of the SHANK3 gene are causally associated with brain disorders such as autism spectrum disorders and schizophrenia. However, recent in vitro and in vivo functional studies and expression profiling in various tissues and cell types suggest that Shank3 also plays a role in cardiac function and dysfunction. For example, Shank3 interacts with phospholipase Cβ1b (PLCβ1b) in cardiomyocytes, regulating its localization to the sarcolemma and its role in mediating Gq-induced signaling. In addition, changes in cardiac morphology and function associated with myocardial infarction and aging have been investigated in a few Shank3 mutant mouse models. This review highlights these results and potential underlying mechanisms, and predicts additional molecular functions of Shank3 based on its protein interactors in the PSD, which are also highly expressed and function in the heart. Finally, we provide perspectives and possible directions for future studies to better understand the roles of Shank3 in the heart.
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Affiliation(s)
- Yoonhee Kim
- Department of Neuroscience, Korea University College of Medicine, Seoul, Republic of Korea
| | - Tae Hee Ko
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Anam Hospital, Seoul, Republic of Korea
| | - Chunmei Jin
- Department of Neuroscience, Korea University College of Medicine, Seoul, Republic of Korea
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon, Republic of Korea
| | - Yinhua Zhang
- Department of Neuroscience, Korea University College of Medicine, Seoul, Republic of Korea
| | - Hyae Rim Kang
- Department of Neuroscience, Korea University College of Medicine, Seoul, Republic of Korea
- BK21 Graduate Program, Department of Biomedical Sciences, Korea University College of Medicine, Seoul, Republic of Korea
| | - Ruiying Ma
- Department of Neuroscience, Korea University College of Medicine, Seoul, Republic of Korea
- BK21 Graduate Program, Department of Biomedical Sciences, Korea University College of Medicine, Seoul, Republic of Korea
| | - Huiling Li
- Department of Neuroscience, Korea University College of Medicine, Seoul, Republic of Korea
- BK21 Graduate Program, Department of Biomedical Sciences, Korea University College of Medicine, Seoul, Republic of Korea
| | - Jong-Il Choi
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Anam Hospital, Seoul, Republic of Korea
- BK21 Graduate Program, Department of Biomedical Sciences, Korea University College of Medicine, Seoul, Republic of Korea
- *Correspondence: Jong-Il Choi, ; Kihoon Han,
| | - Kihoon Han
- Department of Neuroscience, Korea University College of Medicine, Seoul, Republic of Korea
- BK21 Graduate Program, Department of Biomedical Sciences, Korea University College of Medicine, Seoul, Republic of Korea
- *Correspondence: Jong-Il Choi, ; Kihoon Han,
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4
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Rennie M, Lin G, Scarlata S. Multiple functions of phospholipase Cβ1 at a glance. J Cell Sci 2022; 135:276667. [PMID: 36125065 DOI: 10.1242/jcs.260282] [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: 11/20/2022] Open
Abstract
Phospholipase Cβ (PLCβ) is the main effector of the Gq family of heterotrimeric G proteins that transduces signals from hormones and neurotransmitters into Ca2+ signals. While PLCβ is critical for Ca2+ responses, recent studies have suggested that PLCβ has additional roles independent of its lipase activity. These novel functions are carried out by a cytosolic population of PLCβ that binds and inhibits the component 3 promoter of RNA-induced silencing complex (C3PO) to impact cytosolic RNA populations. Additionally, cytosolic PLCβ binds to stress granule proteins, keeping them dispersed and thus inhibiting stress granule formation. Upon activation of the Gα subunit of Gq (Gαq), cytosolic PLCβ relocalizes to the membrane, releasing C3PO and stress granule proteins, which in turn promotes activation of C3PO and RNA processing, as well as sequestration of specific transcripts into newly formed stress granules. As highlighted in this Cell Science at a Glance and the accompanying poster, the link between Gαq signaling, increased intracellular Ca2+ and changes in RNA processing impacts neuronal cell differentiation and may also affect neuronal development and dysfunction.
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Affiliation(s)
- Madison Rennie
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA
| | - Guanyu Lin
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA
| | - Suzanne Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA
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5
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Upregulation of Phospholipase C Gene Expression Due to Norepinephrine-Induced Hypertrophic Response. Cells 2022; 11:cells11162488. [PMID: 36010565 PMCID: PMC9406906 DOI: 10.3390/cells11162488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/04/2022] [Accepted: 08/09/2022] [Indexed: 11/28/2022] Open
Abstract
The activation of phospholipase C (PLC) is thought to have a key role in the cardiomyocyte response to several different hypertrophic agents such as norepinephrine, angiotensin II and endothelin-1. PLC activity results in the generation of diacylglycerol and inositol trisphosphate, which are downstream signal transducers for the expression of fetal genes, increased protein synthesis, and subsequent cardiomyocyte growth. In this article, we describe the signal transduction elements that regulate PLC gene expression. The discussion is focused on the norepinephrine- α1-adrenoceptor signaling pathway and downstream signaling processes that mediate an upregulation of PLC isozyme gene expression. Evidence is also indicated to demonstrate that PLC activities self-regulate the expression of PLC isozymes with the suggestion that PLC activities may be part of a coordinated signaling process for the perpetuation of cardiac hypertrophy. Accordingly, from the information provided, it is plausible that specific PLC isozymes could be targeted for the mitigation of cardiac hypertrophy.
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6
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Tappia PS, Ramjiawan B, Dhalla NS. Role of Phospholipase C in Catecholamine-induced Increase in Myocardial Protein Synthesis. Can J Physiol Pharmacol 2022; 100:945-955. [PMID: 35767883 DOI: 10.1139/cjpp-2022-0189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The activation of the α1-adrenoceptor-(α1-AR) by norepinephrine results in the G-protein (Gqα) mediated increase in the phosphoinositide-specific phospholipase C (PLC) activity. The byproducts of PLC hydrolytic activity, namely, 1,2-diacylglycerol and inositol-1,4,5-trisphosphate, are important downstream signal transducers for increased protein synthesis in the cardiomyocyte and the subsequent hypertrophic response. In this article, evidence is outlined to demonstrate the role of cardiomyocyte PLC isozymes in the catecholamine-induced increase in protein synthesis by using a blocker of α1-AR and an inhibitor of PLC. The discussion will be focused on the α1-AR-Gqα-PLC-mediated hypertrophic signaling pathway from the viewpoint that it may compliment the other β1-AR-Gs protein-adenylyl cyclase signal transduction mechanisms in the early stages of cardiac hypertrophy development, but may become more relevant at the late stage of cardiac hypertrophy. From the information provided here, it is suggested that some specific PLC isozymes may potentially serve as important targets for the attenuation of cardiac hypertrophy in the vulnerable patient population at-risk for heart failure.
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Affiliation(s)
- Paramjit S Tappia
- Asper Clinical Research Institute, St. Boniface Hospital, Office of Clinical Research, Winnipeg, Manitoba, Canada;
| | - Bram Ramjiawan
- University of Manitoba, Faculty of Medicine, Winnipeg, Manitoba, Canada;
| | - Naranjan S Dhalla
- St Boniface Hospital Research, 120927, Institute of Cardiovascular Sciences, Albrechtsen Research Centre, Winnipeg, Manitoba, Canada;
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7
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Zhou J, Singh N, Monnier C, Marszalec W, Gao L, Jin J, Frisk M, Louch WE, Verma S, Krishnamurthy P, Nico E, Mulla M, Aistrup GL, Kishore R, Wasserstrom JA. Phosphatidylinositol-4,5-Bisphosphate Binding to Amphiphysin-II Modulates T-Tubule Remodeling: Implications for Heart Failure. Front Physiol 2022; 12:782767. [PMID: 35002765 PMCID: PMC8733645 DOI: 10.3389/fphys.2021.782767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/19/2021] [Indexed: 11/13/2022] Open
Abstract
BIN1 (amphyphysin-II) is a structural protein involved in T-tubule (TT) formation and phosphatidylinositol-4,5-bisphosphate (PIP2) is responsible for localization of BIN1 to sarcolemma. The goal of this study was to determine if PIP2-mediated targeting of BIN1 to sarcolemma is compromised during the development of heart failure (HF) and is responsible for TT remodeling. Immunohistochemistry showed co-localization of BIN1, Cav1.2, PIP2, and phospholipase-Cβ1 (PLCβ1) in TTs in normal rat and human ventricular myocytes. PIP2 levels were reduced in spontaneously hypertensive rats during HF progression compared to age-matched controls. A PIP Strip assay of two native mouse cardiac-specific isoforms of BIN1 including the longest (cardiac BIN1 #4) and shortest (cardiac BIN1 #1) isoforms as well human skeletal BIN1 showed that all bound PIP2. In addition, overexpression of all three BIN1 isoforms caused tubule formation in HL-1 cells. A triple-lysine motif in a short loop segment between two helices was mutated and replaced by negative charges which abolished tubule formation, suggesting a possible location for PIP2 interaction aside from known consensus binding sites. Pharmacological PIP2 depletion in rat ventricular myocytes caused TT loss and was associated with changes in Ca2+ release typically found in myocytes during HF, including a higher variability in release along the cell length and a slowing in rise time, time to peak, and decay time in treated myocytes. These results demonstrate that depletion of PIP2 can lead to TT disruption and suggest that PIP2 interaction with cardiac BIN1 is required for TT maintenance and function.
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Affiliation(s)
- Junlan Zhou
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Neha Singh
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Chloe Monnier
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - William Marszalec
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Li Gao
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Jing Jin
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Michael Frisk
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital, Oslo, Norway.,K. G. Jebsen Cardiac Research Center, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital, Oslo, Norway.,K. G. Jebsen Cardiac Research Center, University of Oslo, Oslo, Norway
| | - Suresh Verma
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Prasanna Krishnamurthy
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Elsa Nico
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Maaz Mulla
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Gary L Aistrup
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Raj Kishore
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - J Andrew Wasserstrom
- Department of Medicine (Cardiology), Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
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8
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Tappia P, Elimban V, Dhalla N. Involvement of phospholipase C in the norepinephrine-induced hypertrophic response in Cardiomyocytes. SCRIPTA MEDICA 2022. [DOI: 10.5937/scriptamed53-36527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Norepinephrine (NE) is known to mediate cardiomyocyte hypertrophy through the G protein coupled a1 -adrenoceptor (a1 -AR) and the activation of the phosphoinositide-specific phospholipase C (PLC). Since the by-products of PLC activity are important downstream signal transducers for cardiac hypertrophy, the role of and the regulatory mechanisms involved in the activation of PLC isozymes in cardiac hypertrophy are highlighted in this review. The discussion is focused to underscore PLC in different experimental models of cardiac hypertrophy, as well as in isolated adult and neonatal cardiomyocytes treated with NE. Particular emphasis is laid concerning the a1 -AR-PLC-mediated hypertrophic signalling pathway. From the information provided, it is evident that the specific activation of PLC isozymes is a primary signalling event in the a1 -AR mediated response to NE as well as initiation and progression of cardiac hypertrophy. Furthermore, the possibility of PLC involvement in the perpetuation of cardiac hypertrophy is also described. It is suggested that specific PLC isozymes may serve as viable targets for the prevention of cardiac hypertrophy in patient population at-risk for the development of heart failure.
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9
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Qifti A, Jackson L, Singla A, Garwain O, Scarlata S. Stimulation of phospholipase Cβ1 by Gα q promotes the assembly of stress granule proteins. Sci Signal 2021; 14:eaav1012. [PMID: 34665639 DOI: 10.1126/scisignal.aav1012] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
[Figure: see text].
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Affiliation(s)
- Androniqi Qifti
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Lela Jackson
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Ashima Singla
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Osama Garwain
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Suzanne Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA 01609, USA
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10
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Muralidharan K, Van Camp MM, Lyon AM. Structure and regulation of phospholipase Cβ and ε at the membrane. Chem Phys Lipids 2021; 235:105050. [PMID: 33422547 DOI: 10.1016/j.chemphyslip.2021.105050] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/28/2020] [Accepted: 01/04/2021] [Indexed: 12/28/2022]
Abstract
Phospholipase C (PLC) β and ε enzymes hydrolyze phosphatidylinositol (PI) lipids in response to direct interactions with heterotrimeric G protein subunits and small GTPases, which are activated downstream of G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs). PI hydrolysis generates second messengers that increase the intracellular Ca2+ concentration and activate protein kinase C (PKC), thereby regulating numerous physiological processes. PLCβ and PLCε share a highly conserved core required for lipase activity, but use different strategies and structural elements to autoinhibit basal activity, bind membranes, and engage G protein activators. In this review, we discuss recent structural insights into these enzymes and the implications for how they engage membranes alone or in complex with their G protein regulators.
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Affiliation(s)
- Kaushik Muralidharan
- Department of Biological Sciences, 560 Oval Drive, Purdue University, West Lafayette, IN, 47907, United States.
| | - Michelle M Van Camp
- Department of Chemistry, 560 Oval Drive, Purdue University, West Lafayette, IN, 47907, United States.
| | - Angeline M Lyon
- Department of Biological Sciences, 560 Oval Drive, Purdue University, West Lafayette, IN, 47907, United States; Department of Chemistry, 560 Oval Drive, Purdue University, West Lafayette, IN, 47907, United States.
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11
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Scarlata S. The role of phospholipase Cβ on the plasma membrane and in the cytosol: How modular domains enable novel functions. Adv Biol Regul 2019; 73:100636. [PMID: 31409535 DOI: 10.1016/j.jbior.2019.100636] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 07/14/2019] [Accepted: 07/25/2019] [Indexed: 01/14/2023]
Abstract
Phospholipase Cβ (PLCβ) is a signaling enzyme activated by G proteins to generate calcium signals. The catalytic core of PLCβ is surrounded by modular domains that mediate the interaction of the enzyme with known protein partners on the plasma membrane. The C-terminal region PLCβ contains a novel coiled-coil domain that is required for Gαq binding and activation. Recent work has shown that this domain also binds a number of cytosolic proteins that regulate protein translation, and that these proteins compete with Gαq for PLCβ binding. The ability of PLCβ to shuttle between the cytosol to impact protein translation and the plasma membrane to mediate calcium signals puts PLCβ in a central role in cell function.
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Affiliation(s)
- Suzanne Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA, 01609, United States.
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12
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Bakhsh AD, Ladas I, Hamshere ML, Bullock M, Kirov G, Zhang L, Taylor PN, Gregory JW, Scott-Coombes D, Völzke H, Teumer A, Mantripragada K, Williams ED, Clifton-Bligh RJ, Williams NM, Ludgate ME. An InDel in Phospholipase-C-B-1 Is Linked with Euthyroid Multinodular Goiter. Thyroid 2018; 28:891-901. [PMID: 29897006 DOI: 10.1089/thy.2017.0312] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Euthyroid multinodular goiter (MNG) is common, but little is known about the genetic variations conferring predisposition. Previously, a family with MNG of adolescent onset was reported in which some family members developed papillary thyroid carcinomas (PTC). METHODS Genome-wide linkage analysis and next-generation sequencing were conducted to identify genetic variants that may confer disease predisposition. A multipoint nonparametric LOD score of 3.01 was obtained, covering 19 cM on chromosome 20p. Haplotype analysis reduced the region of interest to 10 cM. RESULTS Analysis of copy number variation identified an intronic InDel (∼1000 bp) in the PLCB1 gene in all eight affected family members and carriers (an unaffected person who has inherited the genetic trait). This InDel is present in approximately 1% of "healthy" Caucasians. Next-generation sequencing of the region identified no additional disease-associated variant, suggesting a possible role of the InDel. Since PLCB1 contributes to thyrocyte growth regulation, the InDel was investigated in relevant Caucasian cohorts. It was detected in 0/70 PTC but 4/81 unrelated subjects with MNG (three females; age at thyroidectomy 27-59 years; no family history of MNG/PTC). The InDel frequency is significantly higher in MNG subjects compared to controls (χ2 = 5.076; p = 0.024. PLCB1 transcript levels were significantly higher in thyroids with the InDel than without (p < 0.02). CONCLUSIONS The intronic PLCB1 InDel is the first variant found in familial multiple papilloid adenomata-type MNG and in a subset of patients with sporadic MNG. It may function through overexpression, and increased PLC activity has been reported in thyroid neoplasms. The potential role of the deletion as a biomarker to identify MNG patients more likely to progress to PTC merits exploration.
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Affiliation(s)
- Ameen D Bakhsh
- 1 Division of Infection and Immunity, Cardiff University , Cardiff, United Kingdom
| | - Ioannis Ladas
- 1 Division of Infection and Immunity, Cardiff University , Cardiff, United Kingdom
| | - Marian L Hamshere
- 2 Institute of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University , Cardiff, United Kingdom
| | - Martyn Bullock
- 3 Kolling Institute of Medical Research and Department of Endocrinology, University of Sydney , Royal North Shore Hospital, Sydney, Australia
| | - George Kirov
- 2 Institute of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University , Cardiff, United Kingdom
| | - Lei Zhang
- 1 Division of Infection and Immunity, Cardiff University , Cardiff, United Kingdom
| | - Peter N Taylor
- 1 Division of Infection and Immunity, Cardiff University , Cardiff, United Kingdom
| | - John W Gregory
- 1 Division of Infection and Immunity, Cardiff University , Cardiff, United Kingdom
| | - David Scott-Coombes
- 4 Department of Endocrine Surgery; Cardiff University , Cardiff, United Kingdom
| | - Henry Völzke
- 5 Institute for Community Medicine, Study of Health in Pomerania, Ernst Moritz Arndt University , Greifswald, Germany
| | - Alexander Teumer
- 5 Institute for Community Medicine, Study of Health in Pomerania, Ernst Moritz Arndt University , Greifswald, Germany
| | - Kiran Mantripragada
- 2 Institute of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University , Cardiff, United Kingdom
| | - E Dillwyn Williams
- 6 Thyroid Carcinogenesis Research Group, Strangeways Research Laboratory , Wort's Causeway, Cambridge, United Kingdom
| | - Roderick J Clifton-Bligh
- 3 Kolling Institute of Medical Research and Department of Endocrinology, University of Sydney , Royal North Shore Hospital, Sydney, Australia
| | - Nigel M Williams
- 2 Institute of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University , Cardiff, United Kingdom
| | - Marian E Ludgate
- 1 Division of Infection and Immunity, Cardiff University , Cardiff, United Kingdom
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13
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Dahl EF, Wu SC, Healy CL, Harsch BA, Shearer GC, O'Connell TD. Subcellular compartmentalization of proximal Gα q-receptor signaling produces unique hypertrophic phenotypes in adult cardiac myocytes. J Biol Chem 2018; 293:8734-8749. [PMID: 29610273 DOI: 10.1074/jbc.ra118.002283] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 03/13/2018] [Indexed: 12/12/2022] Open
Abstract
G protein-coupled receptors that signal through Gαq (Gq receptors), such as α1-adrenergic receptors (α1-ARs) or angiotensin receptors, share a common proximal signaling pathway that activates phospholipase Cβ1 (PLCβ1), which cleaves phosphatidylinositol 4,5-bisphosphate (PIP2) to produce inositol 1,4,5-trisphosphate (IP3) and diacylglycerol. Despite these common proximal signaling mechanisms, Gq receptors produce distinct physiological responses, yet the mechanistic basis for this remains unclear. In the heart, Gq receptors are thought to induce myocyte hypertrophy through a mechanism termed excitation-transcription coupling, which provides a mechanistic basis for compartmentalization of calcium required for contraction versus IP3-dependent intranuclear calcium required for hypertrophy. Here, we identified subcellular compartmentalization of Gq-receptor signaling as a mechanistic basis for unique Gq receptor-induced hypertrophic phenotypes in cardiac myocytes. We show that α1-ARs co-localize with PLCβ1 and PIP2 at the nuclear membrane. Further, nuclear α1-ARs induced intranuclear PLCβ1 activity, leading to histone deacetylase 5 (HDAC5) export and a robust transcriptional response (i.e. significant up- or down-regulation of 806 genes). Conversely, we found that angiotensin receptors localize to the sarcolemma and induce sarcolemmal PLCβ1 activity, but fail to promote HDAC5 nuclear export, while producing a transcriptional response that is mostly a subset of α1-AR-induced transcription. In summary, these results link Gq-receptor compartmentalization in cardiac myocytes to unique hypertrophic transcription. They suggest a new model of excitation-transcription coupling in adult cardiac myocytes that accounts for differential Gq-receptor localization and better explains distinct physiological functions of Gq receptors.
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Affiliation(s)
| | - Steven C Wu
- Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota 55455 and
| | - Chastity L Healy
- Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota 55455 and
| | - Brian A Harsch
- the Department of Nutritional Sciences, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Gregory C Shearer
- the Department of Nutritional Sciences, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Timothy D O'Connell
- Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota 55455 and
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14
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Udawela M, Scarr E, Boer S, Um JY, Hannan AJ, McOmish C, Felder CC, Thomas EA, Dean B. Isoform specific differences in phospholipase C beta 1 expression in the prefrontal cortex in schizophrenia and suicide. NPJ SCHIZOPHRENIA 2017; 3:19. [PMID: 28560265 PMCID: PMC5441535 DOI: 10.1038/s41537-017-0020-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 03/09/2017] [Accepted: 03/21/2017] [Indexed: 11/09/2022]
Abstract
Our previous study demonstrated that phospholipase C beta 1 mRNA was down-regulated in Brodmann's area 46 from subjects with schizophrenia. However, phospholipase C beta 1 protein has also been shown to be lower in Brodmann's area 8 and 9 from teenage suicide subjects, creating a potential confound in interpreting the findings in schizophrenia due to the high suicide rate associated with this disorder. To begin to reconcile and consolidate these findings, in this study, we measured mRNA and protein levels of phospholipase C beta 1 variants a and b in Brodmann's area 46 and Brodmann's area 9 from subjects with schizophrenia, many of whom were suicide completers, and determined the diagnostic specificity of observed findings. Consistent with our previous study, levels of phospholipase C beta 1 a and b mRNA, but not protein, were lower in Brodmann's area 46 from subjects with schizophrenia. In Brodmann's area 9, phospholipase C beta 1a protein levels were lower in subjects with schizophrenia, while phospholipase C beta 1b mRNA was higher and protein was lower in those that had died of suicide. Altered protein levels in Brodmann's area 9 appeared to be diagnostically specific, as we did not detect these changes in subjects with bipolar disorder, major depressive disorder or suicide completers with no diagnosis of mental illness. We further assessed the relationship between phospholipase C beta 1 and levels of muscarinic receptors (CHRMs) that signal through this protein, in both human and Chrm knockout mouse central nervous system tissue, and found no strong relationship between the two. Understanding central nervous system differences in downstream effector pathways in schizophrenia may lead to improved treatment strategies and help to identify those at risk of suicide.
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Affiliation(s)
- M Udawela
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
| | - E Scarr
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
- Department of Psychiatry, University of Melbourne, Parkville, VIC Australia
| | - S Boer
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
| | - J Y Um
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
- Cardiovascular and Neurology Products Division, Drug Evaluation Department, National Institute of Food and Drug Safety Evaluation, Osong Health Technology Administration Complex, Chungcheongbuk-do, South Korea
| | - A J Hannan
- Epigenetics and Neural Plasticity Laboratory, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
| | - C McOmish
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
| | - C C Felder
- Lilly Research Laboratories, Neuroscience Research Division, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN USA
| | - E A Thomas
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, La Jolla, CA USA
| | - B Dean
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
- Cardiovascular and Neurology Products Division, Drug Evaluation Department, National Institute of Food and Drug Safety Evaluation, Osong Health Technology Administration Complex, Chungcheongbuk-do, South Korea
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15
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Phospholipase Cβ1 induces membrane tubulation and is involved in caveolae formation. Proc Natl Acad Sci U S A 2016; 113:7834-9. [PMID: 27342861 DOI: 10.1073/pnas.1603513113] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Lipid membrane curvature plays important roles in various physiological phenomena. Curvature-regulated dynamic membrane remodeling is achieved by the interaction between lipids and proteins. So far, several membrane sensing/sculpting proteins, such as Bin/amphiphysin/Rvs (BAR) proteins, are reported, but there remains the possibility of the existence of unidentified membrane-deforming proteins that have not been uncovered by sequence homology. To identify new lipid membrane deformation proteins, we applied liposome-based microscopic screening, using unbiased-darkfield microscopy. Using this method, we identified phospholipase Cβ1 (PLCβ1) as a new candidate. PLCβ1 is well characterized as an enzyme catalyzing the hydrolysis of phosphatidylinositol-4,5-bisphosphate (PIP2). In addition to lipase activity, our results indicate that PLCβ1 possessed the ability of membrane tubulation. Lipase domains and inositol phospholipids binding the pleckstrin homology (PH) domain of PLCβ1 were not involved, but the C-terminal sequence was responsible for this tubulation activity. Computational modeling revealed that the C terminus displays the structural homology to the BAR domains, which is well known as a membrane sensing/sculpting domain. Overexpression of PLCβ1 caused plasma membrane tubulation, whereas knockdown of the protein reduced the number of caveolae and induced the evagination of caveolin-rich membrane domains. Taken together, our results suggest a new function of PLCβ1: plasma membrane remodeling, and in particular, caveolae formation.
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16
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Expressing an inhibitor of PLCβ1b sustains contractile function following pressure overload. J Mol Cell Cardiol 2016; 93:12-7. [PMID: 26906633 DOI: 10.1016/j.yjmcc.2016.02.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 01/29/2016] [Accepted: 02/17/2016] [Indexed: 01/19/2023]
Abstract
The activity of phospholipase Cβ1b (PLCβ1b) is selectively elevated in failing myocardium and cardiac expression of PLCβ1b causes contractile dysfunction. PLCβ1b can be selectively inhibited by expressing a peptide inhibitor that prevents sarcolemmal localization. The inhibitory peptide, PLCβ1b-CT was expressed in heart from a mini-gene using adeno-associated virus (rAAV6-PLCβ1b-CT). rAAV6-PLCβ1b-CT, or blank virus, was delivered IV (4×10(9)vg/g body weight) and trans-aortic-constriction (TAC) or sham-operation was performed 8weeks later. Expression of PLCβ1b-CT prevented the loss of contractile function, eliminated lung congestion and improved survival following TAC with either a 'moderate' or 'severe' pressure gradient. Hypertrophy was attenuated but not eliminated. Expression of the PLCβ1b-CT peptide 2-3weeks after TAC reduced contractile dysfunction and lung congestion, without limiting hypertrophy. PLCβ1b inhibition ameliorates pathological responses following acute pressure overload. The targeting of PLCβ1b to the sarcolemma provides the basis for the development of a new class of inotropic agent.
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17
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Grubb DR, Luo J, Woodcock EA. Phospholipase Cβ1b directly binds the SH3 domain of Shank3 for targeting and activation in cardiomyocytes. Biochem Biophys Res Commun 2015; 461:519-24. [DOI: 10.1016/j.bbrc.2015.04.060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 04/10/2015] [Indexed: 12/24/2022]
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18
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Grubb DR, Crook B, Ma Y, Luo J, Qian HW, Gao XM, Kiriazis H, Du XJ, Gregorevic P, Woodcock EA. The atypical 'b' splice variant of phospholipase Cβ1 promotes cardiac contractile dysfunction. J Mol Cell Cardiol 2015; 84:95-103. [PMID: 25918049 DOI: 10.1016/j.yjmcc.2015.04.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 04/16/2015] [Accepted: 04/20/2015] [Indexed: 10/23/2022]
Abstract
The activity of the early signaling enzyme, phospholipase Cβ1b (PLCβ1b), is selectively elevated in diseased myocardium and activity increases with disease progression. We aimed to establish the contribution of heightened PLCβ1b activity to cardiac pathology. PLCβ1b, the alternative splice variant, PLCβ1a, and a blank virus were expressed in mouse hearts using adeno-associated viral vectors (rAAV6-FLAG-PLCβ1b, rAAV6-FLAG-PLCβ1a, or rAAV6-blank) delivered intravenously (IV). Following viral delivery, FLAG-PLCβ1b was expressed in all of the chambers of the mouse heart and was localized to the sarcolemma. Heightened PLCβ1b expression caused a rapid loss of contractility, 4-6 weeks, that was fully reversed, within 5 days, by inhibition of protein kinase Cα (PKCα). PLCβ1a did not localize to the sarcolemma and did not affect contractile function. Expression of PLCβ1b, but not PLCβ1a, caused downstream dephosphorylation of phospholamban and depletion of the Ca(2+) stores of the sarcoplasmic reticulum. We conclude that heightened PLCβ1b activity observed in diseased myocardium contributes to pathology by PKCα-mediated contractile dysfunction. PLCβ1b is a cardiac-specific signaling system, and thus provides a potential therapeutic target for the development of well-tolerated inotropic agents for use in failing myocardium.
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Affiliation(s)
- David R Grubb
- Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, 3004 Victoria, Australia
| | - Bryony Crook
- Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, 3004 Victoria, Australia
| | - Yi Ma
- Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, 3004 Victoria, Australia
| | - Jieting Luo
- Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, 3004 Victoria, Australia
| | - Hong Wei Qian
- Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, 3004 Victoria, Australia
| | - Xiao-Ming Gao
- Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, 3004 Victoria, Australia
| | - Helen Kiriazis
- Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, 3004 Victoria, Australia
| | - Xiao-Jun Du
- Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, 3004 Victoria, Australia
| | - Paul Gregorevic
- Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, 3004 Victoria, Australia
| | - Elizabeth A Woodcock
- Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, 3004 Victoria, Australia.
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19
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Cooley N, Grubb DR, Luo J, Woodcock EA. The phosphatidylinositol(4,5)bisphosphate-binding sequence of transient receptor potential channel canonical 4α is critical for its contribution to cardiomyocyte hypertrophy. Mol Pharmacol 2014; 86:399-405. [PMID: 25049082 DOI: 10.1124/mol.114.093690] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Cardiomyocyte hypertrophy requires a source of Ca(2+) distinct from the Ca(2+) that regulates contraction. The canonical transient receptor potential channel (TrpC) family, a family of cation channels regulated by activation of phospholipase C (PLC), has been implicated in this response. Cardiomyocyte hypertrophy downstream of Gq-coupled receptors is mediated specifically by PLCβ1b that is scaffolded onto a SH3 and ankyrin repeat protein 3 (Shank3) complex at the sarcolemma. TrpC4 exists as two splice variants (TrpC4α and TrpC4β) that differ only in an 84-residue sequence that binds to phosphatidylinositol(4,5)bisphosphate (PIP2), the substrate of PLCβ1b. In neonatal rat cardiomyocytes, TrpC4α, but not TrpC4β, coimmunoprecipitated with both PLCβ1b and Shank3. Heightened PLCβ1b expression caused TrpC4α, but not TrpC4β, translocation to the sarcolemma, where it colocalized with PLCβ1b. When overexpressed in cardiomyocytes, TrpC4α, but not TrpC4β, increased cell area (893 ± 18 to 1497 ± 29 mm(2), P < 0.01) and marker gene expression (atrial natriuretic peptide increased by 409 ± 32%, and modulatory calcineurin inhibitory protein 1 by 315 ± 28%, P < 0.01). Dominant-negative TrpC4 reduced hypertrophy initiated by PLCβ1b, or PLCβ1b-coupled receptor activation, by 72 ± 8% and 39 ± 5 %, respectively. We conclude that TrpC4α is selectively involved in mechanisms downstream of PLCβ1b culminating in cardiomyocyte hypertrophy, and that the hypertrophic response is dependent on the TrpC4α splice variant-specific sequence that binds to PIP2.
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Affiliation(s)
- Nicola Cooley
- Molecular Cardiology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - David R Grubb
- Molecular Cardiology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Jieting Luo
- Molecular Cardiology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Elizabeth A Woodcock
- Molecular Cardiology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
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20
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Rayala S, Francis VG, Sivagnanam U, Gummadi SN. N-terminal proline-rich domain is required for scrambling activity of human phospholipid scramblases. J Biol Chem 2014; 289:13206-18. [PMID: 24648509 DOI: 10.1074/jbc.m113.522953] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Human phospholipid scramblase 1 (hPLSCR1), a type II integral class membrane protein, is known to mediate bidirectional scrambling of phospholipids in a Ca(2+)-dependent manner. hPLSCR2, a homolog of hPLSCR1 that lacks N-terminal proline-rich domain (PRD), did not show scramblase activity. We attribute this absence of scramblase activity of hPLSCR2 to the lack of N-terminal PRD. Hence to investigate the above hypothesis, we added the PRD of hPLSCR1 to hPLSCR2 (PRD-hPLSCR2) and checked whether scramblase activity was restored. Functional assays showed that the addition of PRD to hPLSCR2 restored scrambling activity, and deletion of PRD in hPLSCR1 (ΔPRD-hPLSCR1) resulted in a lack of activity. These results suggest that PRD is crucial for the function of the protein. The effects of the PRD deletion in hPLSCR1 and the addition of PRD to hPLSCR2 were characterized using various spectroscopic techniques. Our results clearly showed that hPLSCR1 and PRD-hPLSCR2 showed Ca(2+)-dependent aggregation and scrambling activity, whereas hPLSCR2 and ΔPRD-hPLSCR1 did not show aggregation and activity. Thus we conclude that scramblases exhibit Ca(2+)-dependent scrambling activity by aggregation of protein. Our results provide a possible mechanism for phospholipid scrambling mediated by PLSCRs and the importance of PRD in its function and cellular localization.
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Affiliation(s)
- Sarika Rayala
- From the Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600 036, India
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21
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O'Connell TD, Jensen BC, Baker AJ, Simpson PC. Cardiac alpha1-adrenergic receptors: novel aspects of expression, signaling mechanisms, physiologic function, and clinical importance. Pharmacol Rev 2013; 66:308-33. [PMID: 24368739 DOI: 10.1124/pr.112.007203] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Adrenergic receptors (AR) are G-protein-coupled receptors (GPCRs) that have a crucial role in cardiac physiology in health and disease. Alpha1-ARs signal through Gαq, and signaling through Gq, for example, by endothelin and angiotensin receptors, is thought to be detrimental to the heart. In contrast, cardiac alpha1-ARs mediate important protective and adaptive functions in the heart, although alpha1-ARs are only a minor fraction of total cardiac ARs. Cardiac alpha1-ARs activate pleiotropic downstream signaling to prevent pathologic remodeling in heart failure. Mechanisms defined in animal and cell models include activation of adaptive hypertrophy, prevention of cardiac myocyte death, augmentation of contractility, and induction of ischemic preconditioning. Surprisingly, at the molecular level, alpha1-ARs localize to and signal at the nucleus in cardiac myocytes, and, unlike most GPCRs, activate "inside-out" signaling to cause cardioprotection. Contrary to past opinion, human cardiac alpha1-AR expression is similar to that in the mouse, where alpha1-AR effects are seen most convincingly in knockout models. Human clinical studies show that alpha1-blockade worsens heart failure in hypertension and does not improve outcomes in heart failure, implying a cardioprotective role for human alpha1-ARs. In summary, these findings identify novel functional and mechanistic aspects of cardiac alpha1-AR function and suggest that activation of cardiac alpha1-AR might be a viable therapeutic strategy in heart failure.
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Affiliation(s)
- Timothy D O'Connell
- VA Medical Center (111-C-8), 4150 Clement St., San Francisco, CA 94121. ; or Dr. Timothy D. O'Connell, E-mail:
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22
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Abstract
Phospholipase C (PLC) enzymes convert phosphatidylinositol-4,5-bisphosphate into the second messengers diacylglycerol and inositol-1,4,5-triphosphate. The production of these molecules promotes the release of intracellular calcium and activation of protein kinase C, which results in profound cellular changes. The PLCβ subfamily is of particular interest given its prominent role in cardiovascular and neuronal signaling and its regulation by G protein-coupled receptors, as PLCβ is the canonical downstream target of the heterotrimeric G protein Gαq. However, this is not the only mechanism regulating PLCβ activity. Extensive structural and biochemical evidence has revealed regulatory roles for autoinhibitory elements within PLCβ, Gβγ, small molecular weight G proteins, and the lipid membrane itself. Such complex regulation highlights the central role that this enzyme plays in cell signaling. A better understanding of the molecular mechanisms underlying the control of its activity will greatly facilitate the search for selective small molecule modulators of PLCβ.
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Affiliation(s)
- Angeline M Lyon
- Life Sciences Institute and the Departments of Pharmacology and Biological Chemistry, University of Michigan, Ann Arbor, Michigan
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23
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Abstract
Phosphoinositides (PIs) make up only a small fraction of cellular phospholipids, yet they control almost all aspects of a cell's life and death. These lipids gained tremendous research interest as plasma membrane signaling molecules when discovered in the 1970s and 1980s. Research in the last 15 years has added a wide range of biological processes regulated by PIs, turning these lipids into one of the most universal signaling entities in eukaryotic cells. PIs control organelle biology by regulating vesicular trafficking, but they also modulate lipid distribution and metabolism via their close relationship with lipid transfer proteins. PIs regulate ion channels, pumps, and transporters and control both endocytic and exocytic processes. The nuclear phosphoinositides have grown from being an epiphenomenon to a research area of its own. As expected from such pleiotropic regulators, derangements of phosphoinositide metabolism are responsible for a number of human diseases ranging from rare genetic disorders to the most common ones such as cancer, obesity, and diabetes. Moreover, it is increasingly evident that a number of infectious agents hijack the PI regulatory systems of host cells for their intracellular movements, replication, and assembly. As a result, PI converting enzymes began to be noticed by pharmaceutical companies as potential therapeutic targets. This review is an attempt to give an overview of this enormous research field focusing on major developments in diverse areas of basic science linked to cellular physiology and disease.
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Affiliation(s)
- Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
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24
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Full-length Gα(q)-phospholipase C-β3 structure reveals interfaces of the C-terminal coiled-coil domain. Nat Struct Mol Biol 2013; 20:355-62. [PMID: 23377541 PMCID: PMC3594540 DOI: 10.1038/nsmb.2497] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Accepted: 12/18/2012] [Indexed: 01/18/2023]
Abstract
Phospholipase C-β (PLCβ) is directly activated by Gαq, but the molecular basis for how its distal C-terminal domain (CTD) contributes to maximal activity is poorly understood. Herein we present both the crystal structure and cryo-EM 3D reconstructions of human full-length PLCβ3 in complex with murine Gαq. The distal CTD forms an extended, monomeric helical bundle consisting of three anti-parallel segments with structural similarity to membrane-binding bin–amphiphysin–Rvs (BAR) domains. Sequence conservation of the distal CTD identifies putative membrane and protein interaction sites, the latter of which bind the N-terminal helix of Gαq in both the crystal structure and cryo-EM reconstructions. Functional analysis suggests the distal CTD plays roles in membrane targeting and in optimizing the orientation of the catalytic core at the membrane for maximal rates of lipid hydrolysis.
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25
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Kelemen O, Convertini P, Zhang Z, Wen Y, Shen M, Falaleeva M, Stamm S. Function of alternative splicing. Gene 2013; 514:1-30. [PMID: 22909801 PMCID: PMC5632952 DOI: 10.1016/j.gene.2012.07.083] [Citation(s) in RCA: 515] [Impact Index Per Article: 46.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/21/2012] [Accepted: 07/30/2012] [Indexed: 12/15/2022]
Abstract
Almost all polymerase II transcripts undergo alternative pre-mRNA splicing. Here, we review the functions of alternative splicing events that have been experimentally determined. The overall function of alternative splicing is to increase the diversity of mRNAs expressed from the genome. Alternative splicing changes proteins encoded by mRNAs, which has profound functional effects. Experimental analysis of these protein isoforms showed that alternative splicing regulates binding between proteins, between proteins and nucleic acids as well as between proteins and membranes. Alternative splicing regulates the localization of proteins, their enzymatic properties and their interaction with ligands. In most cases, changes caused by individual splicing isoforms are small. However, cells typically coordinate numerous changes in 'splicing programs', which can have strong effects on cell proliferation, cell survival and properties of the nervous system. Due to its widespread usage and molecular versatility, alternative splicing emerges as a central element in gene regulation that interferes with almost every biological function analyzed.
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Affiliation(s)
- Olga Kelemen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Paolo Convertini
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zhaiyi Zhang
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Yuan Wen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Manli Shen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Marina Falaleeva
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Stefan Stamm
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
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Zhang X, Mak S, Li L, Parra A, Denlinger B, Belmonte C, McNaughton PA. Direct inhibition of the cold-activated TRPM8 ion channel by Gαq. Nat Cell Biol 2012; 14:851-8. [PMID: 22750945 PMCID: PMC3428855 DOI: 10.1038/ncb2529] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2012] [Accepted: 05/22/2012] [Indexed: 12/03/2022]
Abstract
Activation of the TRPM8 ion channel in sensory nerve endings produces a sensation of pleasant coolness. Here we show that inflammatory mediators such as bradykinin and histamine inhibit TRPM8 in intact sensory nerves, but do not do so via conventional signalling pathways. The G-protein subunit Gaq instead binds to TRPM8 and when activated by a Gq-coupled receptor directly inhibits ion channel activity. Deletion of Gaq largely abolished inhibition of TRPM8, and inhibition was rescued by a Gaq chimera whose ability to activate downstream signalling pathways was completely ablated. Activated Gaq protein, but not Gβγ, potently inhibits TRPM8 in excised patches. We conclude that Gaq pre-forms a complex with TRPM8 and inhibits activation of TRPM8, following activation of G-protein coupled receptors, by a direct action. This signalling mechanism may underlie the abnormal cold sensation caused by inflammation.
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Affiliation(s)
- Xuming Zhang
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK.
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27
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Cellular neurochemical characterization and subcellular localization of phospholipase C β1 in rat brain. Neuroscience 2012; 222:239-68. [PMID: 22735577 DOI: 10.1016/j.neuroscience.2012.06.039] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 06/15/2012] [Accepted: 06/15/2012] [Indexed: 11/21/2022]
Abstract
The present study describes a complete and detailed neuroanatomical distribution map of the phospholipase C beta1 (PLCβ1) isoform along the adult rat neuraxis, and defines the phenotype of cells expressing PLCβ1, along with its subcellular localization in cortical neurons as assessed by double-immunofluorescence staining and confocal laser scanning. Immunohistochemical labeling revealed a considerable morphological heterogeneity among PLCβ1-positive cells in the cortex, even though there was a marked predominance of pyramidal morphologies. As an exception to the general non-matching distribution of GFAP and PLCβ1, a high degree of co-expression was observed in radial glia-like processes of the spinal cord white matter. In the somatosensory cortex, the proportion of GABAergic neurons co-stained with PLCβ1 was similar (around 2/3) in layers I, II-III, IV and VI, and considerably lower in layer V (around 2/5). Double immunofluorescence against PLCβ1 and nuclear speckle markers SC-35 and NeuN/Fox3 in isolated nuclei from the rat cortex showed a high overlap of both markers with PLCβ1 within the nuclear matrix. In contrast, there was no apparent co-localization with markers of the nuclear envelope and lamina. Finally, to assess whether the subcellular expression pattern of PLCβ1 involved specifically one of the two splice variants of PLCβ1, we carried out Western blot experiments in cortical subcellular fractions. Notably, PLCβ1a/1b ratios were statistically higher in the cytoplasm than in the nuclear and plasma membrane fractions. These results provide a deeper knowledge of the cellular distribution of the PLCβ1 isoform in different cell subtypes of the rat brain, and of its presence in the neuronal nuclear compartment.
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Grubb DR, Luo J, Yu YL, Woodcock EA. Scaffolding protein Homer 1c mediates hypertrophic responses downstream of Gq in cardiomyocytes. FASEB J 2011; 26:596-603. [PMID: 22012123 DOI: 10.1096/fj.11-190330] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Activation of the heterotrimeric G protein, Gq, causes cardiomyocyte hypertrophy in vivo and in cell models. Responses to activated Gq in cardiomyocytes are mediated exclusively by phospholipase Cβ1b (PLCβ1b), because it localizes at the sarcolemma by binding to Shank3, a high-molecular-weight (MW) scaffolding protein. Shank3 can bind to the Homer family of low-MW scaffolding proteins that fine tune Ca(2+) signaling by facilitating crosstalk between Ca(2+) channels at the cell surface with those on intracellular Ca(2+) stores. Activation of α(1)-adrenergic receptors, expression of constitutively active Gαq (GαqQL), or PLCβ1b initiated cardiomyocyte hypertrophy and increased Homer 1c mRNA expression, by 1.6 ± 0.18-, 1.9 ± 0.17-, and 1.5 ± 0.07-fold, respectively (means ± se, 6 independent experiments, P<0.05). Expression of Homer 1c induced an increase in cardiomyocyte area from 853 ± 27 to 1146 ± 31 μm(2) (P<0.05); furthermore, expression of dominant-negative Homer (Homer 1a) reversed the increase in cell size caused by α(1)-adrenergic agonist or PLCβ1b treatment (1503±48 to 996±28 and 1626±48 to 828±31 μm(2), respectively, P<0.05). Homer proteins were localized near the sarcolemma, associated with Shank3 and phospholipase Cβ1b. We conclude that Gq-mediated hypertrophy involves activation of PLCβ1b scaffolded onto a Shank3/Homer complex. Signaling downstream of Homer 1c is necessary and sufficient for Gq-initiated hypertrophy.
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Affiliation(s)
- David R Grubb
- Molecular Cardiology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne,Victoria, Australia
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Shpakov AO. Signal protein-derived peptides as functional probes and regulators of intracellular signaling. JOURNAL OF AMINO ACIDS 2011; 2011:656051. [PMID: 22312467 PMCID: PMC3268021 DOI: 10.4061/2011/656051] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 06/01/2011] [Indexed: 12/21/2022]
Abstract
The functionally important regions of signal proteins participating in their specific interaction and responsible for transduction of hormonal signal into cell are rather short in length, having, as a rule, 8 to 20 amino acid residues. Synthetic peptides corresponding to these regions are able to mimic the activated form of full-size signal protein and to trigger signaling cascades in the absence of hormonal stimulus. They modulate protein-protein interaction and influence the activity of signal proteins followed by changes in their regulatory and catalytic sites. The present review is devoted to the achievements and perspectives of the study of signal protein-derived peptides and to their application as selective and effective regulators of hormonal signaling systems in vitro and in vivo. Attention is focused on the structure, biological activity, and molecular mechanisms of action of peptides, derivatives of the receptors, G protein α subunits, and the enzymes generating second messengers.
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Affiliation(s)
- Alexander O Shpakov
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Thorez avenue 44, 194223 St. Petersburg, Russia
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Udawela M, Scarr E, Hannan AJ, Thomas EA, Dean B. Phospholipase C beta 1 expression in the dorsolateral prefrontal cortex from patients with schizophrenia at different stages of illness. Aust N Z J Psychiatry 2011; 45:140-7. [PMID: 21091263 DOI: 10.3109/00048674.2010.533364] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Our recent microarray study detected decreases in the expression of phospholipase C beta 1 mRNA in the dorsolateral prefrontal cortex from subjects with schizophrenia at different stages of illness. Thus we aimed to validate and extend these findings. METHOD We measured levels of mRNA and protein for phospholipase C beta 1 variant a and b using real-time PCR and western blot analysis, respectively, in the dorsolateral prefrontal cortex from subjects with schizophrenia, who had a short (< 7 years) or long (> 22 years) duration of illness. RESULTS Compared to age/sex matched controls, levels of phospholipase C beta 1 variant a and b mRNAs were decreased (-33% and -50%, respectively) in short duration schizophrenia. By contrast, only variant a mRNA was decreased (-24%) in long duration schizophrenia. There was no significant difference in the protein levels of either phospholipase C beta 1 variant in schizophrenia, irrespective of duration of illness (variant a; P = 0.84, variant b; P = 0.73). CONCLUSION Our data confirm that phospholipase C beta 1 transcript levels are decreased in the dorsolateral prefrontal cortex from subjects with schizophrenia. However, the changes in levels of mRNA do not translate into a change at the level of protein. It is possible protein expression is regulated independently of mRNA and it remains to be determined whether there is a functional consequence of this change in mRNA relating to the pathophysiology of schizophrenia.
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Affiliation(s)
- Madhara Udawela
- Rebecca L. Cooper Research Laboratories, Mental Health Research Institute, Parkville, Victoria, Australia.
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Grubb DR, Iliades P, Cooley N, Yu YL, Luo J, Filtz TM, Woodcock EA. Phospholipase Cbeta1b associates with a Shank3 complex at the cardiac sarcolemma. FASEB J 2010; 25:1040-7. [PMID: 21148417 DOI: 10.1096/fj.10-171470] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Activation of the heterotrimeric G protein Gq causes cardiomyocyte hypertrophy in vivo and in cell models. Our previous studies have shown that responses to activated Gq in cardiomyocytes are mediated exclusively by phospholipase Cβ1b (PLCβ1b), because only this PLCβ subtype localizes at the cardiac sarcolemma. In the current study, we investigated the proteins involved in targeting PLCβ1b to the sarcolemma in neonatal rat cardiomyocytes. PLCβ1b, but not PLCβ1a, coimmunoprecipitated with the high-MW scaffolding protein SH3 and ankyrin repeat protein 3 (Shank3), as well as the known Shank3-interacting protein α-fodrin. The 32-aa splice-variant-specific C-terminal tail of PLCβ1b also associated with Shank3 and α-fodrin, indicating that PLCβ1b binds via the C-terminal sequence. Shank3 colocalized with PLCβ1b at the sarcolemma, and both proteins were enriched in the light membrane fractions. Knockdown of Shank3 using siRNA reduced PLC activation and downstream hypertrophic responses, demonstrating the importance of sarcolemmal localization for PLC signaling. These data indicate that PLCβ1b associates with a Shank3 complex at the cardiac sarcolemma via its splice-variant-specific C-terminal tail. Sarcolemmmal localization is central to PLC activation and subsequent downstream signaling following Gq-coupled receptor activation.
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Affiliation(s)
- David R Grubb
- Baker International Diabetes Institute, 75 Commercial Road, Melbourne, 3004, VIC, Australia
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Fukami K, Inanobe S, Kanemaru K, Nakamura Y. Phospholipase C is a key enzyme regulating intracellular calcium and modulating the phosphoinositide balance. Prog Lipid Res 2010; 49:429-37. [PMID: 20553968 DOI: 10.1016/j.plipres.2010.06.001] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Spatial and temporal activation of phosphoinositide turnover enables eukaryotic cells to perform various functions such as cell proliferation/differentiation, fertilization, neuronal functions, and cell motility. In this system, phospholipase C (PLC) is a key enzyme, which hydrolyzes phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2)) into two second messengers, inositol 1,4,5-trisphosphate (Ins(1,4,5)P(3)) and diacylglycerol (DAG). Ins(1,4,5)P(3) triggers the release of calcium from intracellular stores, and DAG mediates the activation of protein kinase C (PKC). In parallel, PI(4,5)P(2) also directly regulates a variety of cellular functions, including cytoskeletal remodeling, cytokinesis, phagocytosis, membrane dynamics, and channel activity, in addition to its role as a substrate for PLC and phosphatidylinositol 3-kinase (PI3K), which generates PI(3,4,5)P(3). An imbalance of these phosphoinositides contributes to the pathogeneses of various human diseases. Therefore, strict regulation of the levels of PI(4,5)P(2) and PI(3,4,5)P(3) by PLC or other interconverting enzymes is necessary for cellular functions. In this review, we focus on the roles of PLC as a calcium-regulating enzyme and as a modulator of the phosphoinositide balance.
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Affiliation(s)
- Kiyoko Fukami
- Laboratory of the Genome and Biosignals, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo, Japan.
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Woodcock EA, Grubb DR, Filtz TM, Marasco S, Luo J, McLeod-Dryden TJ, Kaye DM, Sadoshima J, Du XJ, Wong C, McMullen JR, Dart AM. Selective activation of the “b” splice variant of phospholipase Cβ1 in chronically dilated human and mouse atria. J Mol Cell Cardiol 2009; 47:676-83. [DOI: 10.1016/j.yjmcc.2009.08.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 08/20/2009] [Accepted: 08/20/2009] [Indexed: 11/15/2022]
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Filtz TM, Grubb DR, McLeod-Dryden TJ, Luo J, Woodcock EA. Gq-initiated cardiomyocyte hypertrophy is mediated by phospholipase Cbeta1b. FASEB J 2009; 23:3564-70. [PMID: 19564249 DOI: 10.1096/fj.09-133983] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Activation of the heterotrimeric G protein Gq causes cardiomyocyte hypertrophy in vivo and in cell culture models. Hypertrophic responses induced by pressure or volume overload are exacerbated by increased Gq activity and ameliorated by Gq inhibition. Gq activates phospholipase Cbeta (PLCbeta) subtypes, resulting in generation of the intracellular messengers inositol(1,4,5)tris-phosphate [Ins(1,4,5)P(3)] and sn-1,2-diacylglycerol (DAG), which regulate intracellular Ca(2+) and conventional protein kinase C subtypes, respectively. Gq can also signal independently of PLCbeta, and the involvement of either Ins(1,4,5)P(3) or DAG in cardiomyocyte hypertrophy has not been unequivocally established. Overexpression of one splice variant of PLCbeta1, specifically PLCbeta1b, in neonatal rat cardiomyocytes causes increased cell size, elevated protein/DNA ratio, and heightened expression of the hypertrophy-related marker gene, atrial natriuretic peptide. The other splice variant, PLCbeta1a, had no effect. Expression of a 32-aa C-terminal PLCbeta1b peptide, which competes with PLCbeta1b for sarcolemmal association, prevented PLC activation and eliminated hypertrophic responses initiated by Gq or Gq-coupled alpha(1)-adrenergic receptors. In contrast, a PLCbeta1a C-terminal peptide altered neither PLC activity nor cellular hypertrophy. We conclude that hypertrophic responses initiated by Gq are mediated specifically by PLCbeta1b. Preventing PLCbeta1b association with the sarcolemma may provide a useful therapeutic target to limit hypertrophy.
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Affiliation(s)
- Theresa M Filtz
- Molecular Cardiology Laboratory, Baker IDI Heart and Diabetes Institute, PO Box 6492, St. Kilda Rd. Central, Melbourne 8008, VIC, Australia
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Balijepalli RC, Kamp TJ. Caveolae, ion channels and cardiac arrhythmias. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2009; 98:149-60. [PMID: 19351512 DOI: 10.1016/j.pbiomolbio.2009.01.012] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Caveolae are specialized membrane microdomains enriched in cholesterol and sphingolipids which are present in multiple cell types including cardiomyocytes. Along with the essential scaffolding protein caveolin-3, a number of different ion channels and transporters have been localized to caveolae in cardiac myocytes including L-type Ca2+ channels (Ca(v)1.2), Na+ channels (Na(v)1.5), pacemaker channels (HCN4), Na+/Ca2+ exchanger (NCX1) and others. Closely associated with these channels are specific macromolecular signaling complexes that provide highly localized regulation of the channels. Mutations in the caveolin-3 gene (CAV3) have been linked with the congenital long QT syndrome (LQT9), and mutations in caveolar-localized ion channels may contribute to other inherited arrhythmias. Changes in the caveolar microdomain in acquired heart disease may also lead to dysregulation and dysfunction of ion channels, altering the risk of arrhythmias in conditions such as heart failure. This review highlights the existing evidence identifying and characterizing ion channels localized to caveolae in cardiomyocytes and their role in arrhythmogenesis.
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Affiliation(s)
- Ravi C Balijepalli
- Department of Medicine, Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, WI 53792, USA
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Abstract
Arrhythmias arise from a complex interaction between structural changes in the myocardium and changes in cellular electrophysiology. Electrophysiological balance requires precise control of sarcolemmal ion channels and exchangers, many of which are regulated by phospholipid, phosphatidylinositol(4,5)bisphosphate. Phosphatidylinositol(4,5)bisphosphate is the immediate precursor of inositol(1,4,5)trisphosphate, a regulator of intracellular Ca2+ signalling and, therefore, a potential contributor to arrhythmogenesis by altering Ca2+ homeostasis. The aim of the present review is to outline current evidence that this signalling pathway can be a player in the initiation or maintenance of arrhythmias.
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Affiliation(s)
- Elizabeth A Woodcock
- Molecular Cardiology Laboratory, Baker IDI Heart and Diabetes Institute, PO Box 6492, St Kilda Road Central, Melbourne, 8008 Victoria, Australia.
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