1
|
Zheng L, Shi W, Liu B, Duan B, Sorgen P. Evaluation of Tyrosine Kinase Inhibitors Loaded Injectable Hydrogels for Improving Connexin43 Gap Junction Intercellular Communication. ACS APPLIED MATERIALS & INTERFACES 2024; 16:1985-1998. [PMID: 38175743 PMCID: PMC11061860 DOI: 10.1021/acsami.3c10923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
Myocardial infarction (MI) is one of the leading causes of death in the developed world, and the loss of cardiomyocytes plays a critical role in the pathogenesis of heart failure. Implicated in this process is a decrease in gap junction intercellular communication due to remodeling of Connexin43 (Cx43). We previously identified that intraperitoneal injection of the Pyk2 inhibitor PF4618433 reduced infarct size, maintained Cx43 at the intercalated disc in left ventricle hypertrophic myocytes, and improved cardiac function in an MI animal model of heart failure. With the emergence of injectable hydrogels as a therapeutic toward the regeneration of cardiac tissue after MI, here, we provide proof of concept that the release of tyrosine kinase inhibitors from hydrogels could have beneficial effects on cardiomyocytes. We developed an injectable hydrogel consisting of thiolated hyaluronic acid and P123-maleimide micelles that can incorporate PF4618433 as well as the Src inhibitor Saracatinib and achieved sustained release (of note, Src activates Pyk2). Using neonatal rat ventricular myocytes in the presence of a phorbol ester, endothelin-1, or phenylephrine to stimulate cardiac hypertrophy, the release of PF4618433 from the hydrogel had the same ability to decrease Cx43 tyrosine phosphorylation and maintain Cx43 localization at the plasma membrane as when directly added to the growth media. Additional beneficial effects included decreases in apoptosis, the hypertrophic marker atrial natriuretic peptide (ANP), and serine kinases upregulated in hypertrophy. Finally, the presence of both PF4618433 and Saracatinib further decreased the level of ANP and apoptosis than each inhibitor alone, suggesting that a combinatorial approach may be most beneficial. These findings provide the groundwork to test if tyrosine kinase inhibitor release from hydrogels will have a beneficial effect in an animal model of MI-induced heart failure.
Collapse
Affiliation(s)
- Li Zheng
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Wen Shi
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Bo Liu
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Bin Duan
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Surgery, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Paul Sorgen
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| |
Collapse
|
2
|
Al-attar R, Jargstorf J, Romagnuolo R, Jouni M, Alibhai FJ, Lampe PD, Solan JL, Laflamme MA. Casein Kinase 1 Phosphomimetic Mutations Negatively Impact Connexin-43 Gap Junctions in Human Pluripotent Stem Cell-Derived Cardiomyocytes. Biomolecules 2024; 14:61. [PMID: 38254663 PMCID: PMC10813327 DOI: 10.3390/biom14010061] [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: 11/10/2023] [Revised: 12/14/2023] [Accepted: 12/25/2023] [Indexed: 01/24/2024] Open
Abstract
The transplantation of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) has shown promise in preclinical models of myocardial infarction, but graft myocardium exhibits incomplete host-graft electromechanical integration and a propensity for pro-arrhythmic behavior. Perhaps contributing to this situation, hPSC-CM grafts show low expression of connexin 43 (Cx43), the major gap junction (GJ) protein, in ventricular myocardia. We hypothesized that Cx43 expression and function could be rescued by engineering Cx43 in hPSC-CMs with a series of phosphatase-resistant mutations at three casein kinase 1 phosphorylation sites (Cx43-S3E) that have been previously reported to stabilize Cx43 GJs and reduce arrhythmias in transgenic mice. However, contrary to our predictions, transgenic Cx43-S3E hPSC-CMs exhibited reduced Cx43 expression relative to wild-type cells, both at baseline and following ischemic challenge. Cx43-S3E hPSC-CMs showed correspondingly slower conduction velocities, increased automaticity, and differential expression of other connexin isoforms and various genes involved in cardiac excitation-contraction coupling. Cx43-S3E hPSC-CMs also had phosphorylation marks associated with Cx43 GJ internalization, a finding that may account for their impaired GJ localization. Taken collectively, our data indicate that the Cx43-S3E mutation behaves differently in hPSC-CMs than in adult mouse ventricular myocytes and that multiple biological factors likely need to be addressed synchronously to ensure proper Cx43 expression, localization, and function.
Collapse
Affiliation(s)
- Rasha Al-attar
- McEwen Stem Cell Institute, University Health Network, Toronto, ON M5G 1L7, Canada; (R.A.-a.); (J.J.); (R.R.); (M.J.); (F.J.A.)
| | - Joseph Jargstorf
- McEwen Stem Cell Institute, University Health Network, Toronto, ON M5G 1L7, Canada; (R.A.-a.); (J.J.); (R.R.); (M.J.); (F.J.A.)
| | - Rocco Romagnuolo
- McEwen Stem Cell Institute, University Health Network, Toronto, ON M5G 1L7, Canada; (R.A.-a.); (J.J.); (R.R.); (M.J.); (F.J.A.)
| | - Mariam Jouni
- McEwen Stem Cell Institute, University Health Network, Toronto, ON M5G 1L7, Canada; (R.A.-a.); (J.J.); (R.R.); (M.J.); (F.J.A.)
| | - Faisal J. Alibhai
- McEwen Stem Cell Institute, University Health Network, Toronto, ON M5G 1L7, Canada; (R.A.-a.); (J.J.); (R.R.); (M.J.); (F.J.A.)
| | - Paul D. Lampe
- Translational Research Program, Public Health Sciences and Human Biology Divisions, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; (P.D.L.); (J.L.S.)
| | - Joell L. Solan
- Translational Research Program, Public Health Sciences and Human Biology Divisions, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; (P.D.L.); (J.L.S.)
| | - Michael A. Laflamme
- McEwen Stem Cell Institute, University Health Network, Toronto, ON M5G 1L7, Canada; (R.A.-a.); (J.J.); (R.R.); (M.J.); (F.J.A.)
- Peter Munk Cardiac Centre, University Health Network, Toronto, ON M5G 1L7, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5G 1L7, Canada
| |
Collapse
|
3
|
Zheng L, Spagnol G, Gandhi DR, Sharma K, Kumar V, Patel KP, Sorgen PL. Inhibition of Pyk2 Improves Cx43 Intercalated Disc Localization, Infarct Size, and Cardiac Function in Rats With Heart Failure. Circ Heart Fail 2023; 16:e010294. [PMID: 37465947 PMCID: PMC10524803 DOI: 10.1161/circheartfailure.122.010294] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 05/12/2023] [Indexed: 07/20/2023]
Abstract
BACKGROUND Heart failure causes changes in Cx43 (Connexin43) regulation that are associated with arrhythmic heart disease. Pyk2 (proline-rich tyrosine kinase 2) is activated in cardiomyopathies and phosphorylates Cx43 to decrease intercellular communication. This study was designed to determine if Pyk2 inhibition improves cardiac function in a myocardial infarction (MI)-induced heart failure model in rats. METHODS MI (ligation of left anterior descending artery) rats were treated with the Pyk2 inhibitor PF4618433. Hemodynamic and structural parameters were monitored in Sham (n=5), MI-vehicle (n=5), and MI-PF4618433 (n=8) groups. Heart tissues were collected after 6 weeks to assess Pyk2 and Cx43 protein level and localization. RESULTS PF4618433 produced no observed adverse effects and inhibited ventricular Pyk2. PF4618433 reduced the MI infarct size from 34% to 17% (P=0.007). PF4618433 improved stroke volume (P=0.031) and cardiac output (P=0.009) in comparison to MI-vehicle with values similar to the Sham group. PF4618433 also led to an increase in the ejection fraction (P=0.002) and fractional shortening (P=0.006) when compared with the MI-vehicle (32% and 35% improvement, respectively) yet were lower in comparison with the Sham group. Pyk2 inhibition decreased Cx43 tyrosine phosphorylation (P=0.043) and maintained Cx43 at the intercalated disc in the distal ventricle 6 weeks post-MI. CONCLUSIONS Unlike other attempts to decrease Cx43 remodeling after MI-induced heart failure, inhibition of Pyk2 activity maintained Cx43 at the intercalated disc. This may have aided in the reduced infarct size (acute time frame) and improved cardiac function (chronic time frame). Additionally, we provide evidence that Pyk2 is activated following MI in human left ventricle, implicating a novel potential target for therapy in patients with heart failure.
Collapse
Affiliation(s)
- Li Zheng
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Gaelle Spagnol
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Devashri R. Gandhi
- Department of Genetics, Cell Biology, and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Kanika Sharma
- Department of Genetics, Cell Biology, and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Vikas Kumar
- Department of Genetics, Cell Biology, and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Kaushik P. Patel
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Paul L. Sorgen
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| |
Collapse
|
4
|
Zhang M, Wang ZZ, Chen NH. Connexin 43 Phosphorylation: Implications in Multiple Diseases. Molecules 2023; 28:4914. [PMID: 37446576 DOI: 10.3390/molecules28134914] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 06/16/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023] Open
Abstract
Connexin 43 (Cx43) is most widely distributed in mammals, especially in the cardiovascular and nervous systems. Its phosphorylation state has been found to be regulated by the action of more than ten kinases and phosphatases, including mitogen-activated protein kinase/extracellular signaling and regulating kinase signaling. In addition, the phosphorylation status of different phosphorylation sites affects its own synthesis and assembly and the function of the gap junctions (GJs) to varying degrees. The phosphorylation of Cx43 can affect the permeability, electrical conductivity, and gating properties of GJs, thereby having various effects on intercellular communication and affecting physiological or pathological processes in vitro and in vivo. Therefore, clarifying the relationship between Cx43 phosphorylation and specific disease processes will help us better understand the disease. Based on the above clinical and preclinical findings, we present in this review the functional significance of Cx43 phosphorylation in multiple diseases and discuss the potential of Cx43 as a drug target in Cx43-related disease pathophysiology, with an emphasis on the importance of connexin 43 as an emerging therapeutic target in cardiac and neuroprotection.
Collapse
Affiliation(s)
- Meng Zhang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100050, China
| | - Zhen-Zhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100050, China
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100050, China
| |
Collapse
|
5
|
LRP6-mediated phosphorylation of connexin43 in myocardial infarction. iScience 2023; 26:106160. [PMID: 36879803 PMCID: PMC9985046 DOI: 10.1016/j.isci.2023.106160] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 10/30/2022] [Accepted: 02/02/2023] [Indexed: 02/11/2023] Open
Abstract
Ventricular tachycardia (VT) and ventricular fibrillation are most causes of early death in patients with acute myocardial infarction (AMI). Conditional cardiac-specific low-density lipoprotein receptor-related protein 6 (LRP6)-knockout mice with connexin 43 (Cx43) reduction triggered the lethal ventricular arrhythmias. Thus, it is necessary for exploring whether LRP6 and its upstream genes circRNA1615 mediate the phosphorylation of Cx43 in VT of AMI. Here, we showed that circRNA1615 regulated the expression of LRP6 mRNA through sponge adsorption of miR-152-3p. Importantly, LRP6 interference fragments aggravated hypoxia injury of Cx43, while overexpression of LRP6 improved the phosphorylation of Cx43. Subsequently, interference with G-protein alpha subunit (Gαs) downstream of LRP6 further inhibited the phosphorylation of Cx43, along with increasing VT. Our results demonstrated that LRP6 upstream genes circRNA1615 controlled the damage effect and VT in AMI, and LRP6 mediated the phosphorylation of Cx43 via Gαs which played a role in VT of AMI.
Collapse
|
6
|
Youssef AM, Song DK. Lysophosphatidylcholine induces adenosine release from macrophages via TRPM7-mediated mitochondrial activation. Purinergic Signal 2022; 18:317-343. [PMID: 35779163 PMCID: PMC9391566 DOI: 10.1007/s11302-022-09878-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 06/13/2022] [Indexed: 01/04/2023] Open
Abstract
Even though macrophages have the potential to harm tissues through excessive release of inflammatory mediators, they play protective roles to maintain tissue integrity. In this study, we hypothesized that lysophosphatidylcholine (LPC), via G2A and A2B receptors, puts brakes on macrophages by the induction of adenosine release which could contribute to termination of inflammation. Mechanistically, LPC-induced PGE2 production followed by the activation of cAMP/protein kinase A (PKA) pathway which results in the activation of LKB1/AMPK signaling pathway leading to increasing Mg2+ influx concomitantly with an increase in mitochondrial membrane potential (MMP, Δψm) and ATP production. Then, ATP is converted to adenosine intracellularly followed by efflux via ENT1. In a parallel pathway, LPC-induced elevation of cytosolic calcium was essential for adenosine release, and Ca2+/calmodulin signaling cooperated with PKA to regulate ENT1 permeation to adenosine. Pharmacological blockade of TRPM7 and antisense treatment suppressed LPC-induced adenosine release and magnesium influx in bone marrow-derived macrophages (BMDMs). Moreover, LPC suppressed LPS-induced phosphorylation of connexin-43, which may counteract TLR4-mediated inflammatory response. Intriguingly, we found LPC increased netrin-1 production from BMDMs. Netrin-1 induces anti-inflammatory signaling via A2B receptor. In the presence of adenosine deaminase which removes adenosine in the medium, the chemotaxis of macrophages toward LPC was significantly increased. Hypoxia and metabolic acidosis are usually developed in a variety of inflammatory situations such as sepsis. We found LPC augmented hypoxia- or acidosis-induced adenosine release from BMDMs. These results provide evidence of LPC-induced brake-like action on macrophages by adenosine release via cellular magnesium signaling.
Collapse
Affiliation(s)
- Ahmed M Youssef
- Department of Pharmacology, College of Medicine, Hallym University, Chuncheon, Gangwon-do, 24252, Republic of Korea
| | - Dong-Keun Song
- Department of Pharmacology, College of Medicine, Hallym University, Chuncheon, Gangwon-do, 24252, Republic of Korea.
| |
Collapse
|
7
|
Thu VT, Kim HK. Majonoside-R2 Postconditioning Protects Cardiomyocytes Against Hypoxia/Reoxygenation Injury by Attenuating the Expression of HIF1 α and Activating RISK Pathway. J Med Food 2021; 24:1222-1229. [PMID: 34714126 DOI: 10.1089/jmf.2021.k.0083] [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] [Indexed: 11/12/2022] Open
Abstract
Reoxygenation of hypoxic cardiac myocytes can paradoxically induce myocardial injury and affect the recovery processes. Pharmacological postconditioning is an efficient strategy used in clinical practice that protects cardiomyocytes from hypoxia/reoxygenation (HR) injury. Natural products or foods have been known to possess effective cardioprotective properties. Majonoside-R2 (MR2) is a dominant saponin component of Vietnamese ginseng that has several biological effects. In this study, we evaluated the protective effect of MR2 on HR-stimulated cardiomyocytes and investigated the related molecular mechanisms. H9C2 cardiomyocytes were exposed to HR conditions with or without MR2 supplementation. Samples from experimental groups were used to analyze the expression of apoptosis- and activating reperfusion injury salvage kinase (RISK)-related factors in response to HR injury by using enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and Western blotting. Post-treatment, MR2 enhanced cell viability under HR conditions. We found that MR2 suppressed the expression of hypoxia-inducible factor 1-alpha (HIF1α) and transforming growth factor beta 1 (TGFβ1), modulated Akt/GSK3ß/cAMP response element-binding signaling, and regulated gene expression related to apoptosis (B cell lymphoma-extra-large [Bcl-xl], Bcl-2 homologous killer [Bak], Bcl-2 associated X [Bax], and connexin 43 [Cnx43]). Thus, the present findings demonstrate that MR2 protects cardiomyocytes against HR injury by suppressing the expression of HIF1α and activating the RISK pathway.
Collapse
Affiliation(s)
- Vu Thi Thu
- Center for Life Science Research, Faculty of Biology, and VNU University of Science, Vietnam National Univeristy, Hanoi, Vietnam.,The Key Laboratory of Enzyme and Protein Technology, VNU University of Science, Vietnam National Univeristy, Hanoi, Vietnam
| | - Hyoung Kyu Kim
- Cardiovascular and Metabolic Research Center and Inje University, Busan, Korea.,Smart Marine Therapeutic Center, Inje University, Busan, Korea
| |
Collapse
|
8
|
Khalil NN, McCain ML. Engineering the Cellular Microenvironment of Post-infarct Myocardium on a Chip. Front Cardiovasc Med 2021; 8:709871. [PMID: 34336962 PMCID: PMC8316619 DOI: 10.3389/fcvm.2021.709871] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 06/14/2021] [Indexed: 01/02/2023] Open
Abstract
Myocardial infarctions are one of the most common forms of cardiac injury and death worldwide. Infarctions cause immediate necrosis in a localized region of the myocardium, which is followed by a repair process with inflammatory, proliferative, and maturation phases. This repair process culminates in the formation of scar tissue, which often leads to heart failure in the months or years after the initial injury. In each reparative phase, the infarct microenvironment is characterized by distinct biochemical, physical, and mechanical features, such as inflammatory cytokine production, localized hypoxia, and tissue stiffening, which likely each contribute to physiological and pathological tissue remodeling by mechanisms that are incompletely understood. Traditionally, simplified two-dimensional cell culture systems or animal models have been implemented to elucidate basic pathophysiological mechanisms or predict drug responses following myocardial infarction. However, these conventional approaches offer limited spatiotemporal control over relevant features of the post-infarct cellular microenvironment. To address these gaps, Organ on a Chip models of post-infarct myocardium have recently emerged as new paradigms for dissecting the highly complex, heterogeneous, and dynamic post-infarct microenvironment. In this review, we describe recent Organ on a Chip models of post-infarct myocardium, including their limitations and future opportunities in disease modeling and drug screening.
Collapse
Affiliation(s)
- Natalie N Khalil
- Laboratory for Living Systems Engineering, Department of Biomedical Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States
| | - Megan L McCain
- Laboratory for Living Systems Engineering, Department of Biomedical Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States.,Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| |
Collapse
|
9
|
Hirschhäuser C, Lissoni A, Görge PM, Lampe PD, Heger J, Schlüter KD, Leybaert L, Schulz R, Boengler K. Connexin 43 phosphorylation by casein kinase 1 is essential for the cardioprotection by ischemic preconditioning. Basic Res Cardiol 2021; 116:21. [PMID: 33751227 PMCID: PMC7985055 DOI: 10.1007/s00395-021-00861-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 03/10/2021] [Indexed: 02/07/2023]
Abstract
Myocardial connexin 43 (Cx43) forms gap junctions and hemichannels, and is also present within subsarcolemmal mitochondria. The protein is phosphorylated by several kinases including mitogen-activated protein kinase (MAPK), protein kinase C (PKC), and casein kinase 1 (CK1). A reduction in Cx43 content abrogates myocardial infarct size reduction by ischemic preconditioning (IPC). The present study characterizes the contribution of Cx43 phosphorylation towards mitochondrial function, hemichannel activity, and the cardioprotection by IPC in wild-type (WT) mice and in mice in which Cx43-phosphorylation sites targeted by above kinases are mutated to non-phosphorylatable residues (Cx43MAPKmut, Cx43PKCmut, and Cx43CK1mut mice). The amount of Cx43 in the left ventricle and in mitochondria was reduced in all mutant strains compared to WT mice and Cx43 phosphorylation was altered at residues not directly targeted by the mutations. Whereas complex 1 respiration was reduced in all strains, complex 2 respiration was decreased in Cx43CK1mut mice only. In Cx43 epitope-mutated mice, formation of reactive oxygen species and opening of the mitochondrial permeability transition pore were not affected. The hemichannel open probability was reduced in Cx43PKCmut and Cx43CK1mut but not in Cx43MAPKmut cardiomyocytes. Infarct size in isolated saline-perfused hearts after ischemia/reperfusion (45 min/120 min) was comparable between genotypes and was significantly reduced by IPC (3 × 3 min ischemia/5 min reperfusion) in WT, Cx43MAPKmut, and Cx43PKCmut, but not in Cx43CK1mut mice, an effect independent from the amount of Cx43 and the probability of hemichannel opening. Taken together, our study shows that alterations of Cx43 phosphorylation affect specific cellular functions and highlights the importance of Cx43 phosphorylation by CK1 for IPC's cardioprotection.
Collapse
Affiliation(s)
- Christine Hirschhäuser
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany
| | - Alessio Lissoni
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | | | - Paul D Lampe
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Jacqueline Heger
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany
| | - Klaus-Dieter Schlüter
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Rainer Schulz
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany
| | - Kerstin Boengler
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany.
| |
Collapse
|
10
|
Zheng L, Trease AJ, Katsurada K, Spagnol G, Li H, Shi W, Duan B, Patel KP, Sorgen PL. Inhibition of Pyk2 and Src activity improves Cx43 gap junction intercellular communication. J Mol Cell Cardiol 2020; 149:27-40. [PMID: 32956670 DOI: 10.1016/j.yjmcc.2020.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 09/08/2020] [Accepted: 09/10/2020] [Indexed: 11/24/2022]
Abstract
Identification of proteins that interact with Cx43 has been instrumental in the understanding of gap junction (GJ) regulation. An in vitro phosphorylation screen identified that Protein tyrosine kinase 2 beta (Pyk2) phosphorylated purified Cx43CT and this led us to characterize the impact of this phosphorylation on Cx43 function. Mass spectrometry identified Pyk2 phosphorylates Cx43 residues Y247, Y265, Y267, and Y313. Western blot and immunofluorescence staining using HeLaCx43 cells, HEK 293 T cells, and neonatal rat ventricular myocytes (NRVMs) revealed Pyk2 can be activated by Src and active Pyk2 interacts with Cx43 at the plasma membrane. Overexpression of Pyk2 increases Cx43 phosphorylation and knock-down of Pyk2 decreases Cx43 phosphorylation, without affecting the level of active Src. In HeLaCx43 cells treated with PMA to activate Pyk2, a decrease in Cx43 GJ intercellular communication (GJIC) was observed when assayed by dye transfer. Moreover, PMA activation of Pyk2 could be inhibited by the small molecule PF4618433. This partially restored GJIC, and when paired with a Src inhibitor, returned GJIC to the no PMA control-level. The ability of Pyk2 and Src inhibitors to restore Cx43 function in the presence of PMA was also observed in NRVMs. Additionally, an animal model of myocardial infarction induced heart failure showed a higher level of active Pyk2 activity and increased interaction with Cx43 in ventricular myocytes. Src inhibitors have been used to reverse Cx43 remodeling and improve heart function after myocardial infarction; however, they alone could not fully restore proper Cx43 function. Our data suggest that Pyk2 may need to be inhibited, in addition to Src, to further (if not completely) reverse Cx43 remodeling and improve intercellular communication.
Collapse
Affiliation(s)
- Li Zheng
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Andrew J Trease
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Kenichi Katsurada
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Gaelle Spagnol
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Hanjun Li
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Wen Shi
- Division of Cardiology, Department of Internal Medicine/Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Bin Duan
- Division of Cardiology, Department of Internal Medicine/Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Kaushik P Patel
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Paul L Sorgen
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| |
Collapse
|
11
|
Ferraro E, Pozhidaeva L, Pitcher DS, Mansfield C, Koh JHB, Williamson C, Aslanidi O, Gorelik J, Ng FS. Prolonged ursodeoxycholic acid administration reduces acute ischaemia-induced arrhythmias in adult rat hearts. Sci Rep 2020; 10:15284. [PMID: 32943714 PMCID: PMC7499428 DOI: 10.1038/s41598-020-72016-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 08/07/2020] [Indexed: 12/13/2022] Open
Abstract
Acute myocardial ischaemia and reperfusion (I-R) are major causes of ventricular arrhythmias in patients with a history of coronary artery disease. Ursodeoxycholic acid (UDCA) has previously been shown to be antiarrhythmic in fetal hearts. This study was performed to investigate if UDCA protects against ischaemia-induced and reperfusion-induced arrhythmias in the adult myocardium, and compares the effect of acute (perfusion only) versus prolonged (2 weeks pre-treatment plus perfusion) UDCA administration. Langendorff-perfused adult Sprague-Dawley rat hearts were subjected to acute regional ischaemia by ligation of the left anterior descending artery (10 min), followed by reperfusion (2 min), and arrhythmia incidence quantified. Prolonged UDCA administration reduced the incidence of acute ischaemia-induced arrhythmias (p = 0.028), with a reduction in number of ventricular ectopic beats during the ischaemic phase compared with acute treatment (10 ± 3 vs 58 ± 15, p = 0.036). No antiarrhythmic effect was observed in the acute UDCA administration group. Neither acute nor prolonged UDCA treatment altered the incidence of reperfusion arrhythmias. The antiarrhythmic effect of UDCA may be partially mediated by an increase in cardiac wavelength, due to the attenuation of conduction velocity slowing (p = 0.03), and the preservation of Connexin43 phosphorylation during acute ischaemia (p = 0.0027). The potential antiarrhythmic effects of prolonged UDCA administration merit further investigation.
Collapse
Affiliation(s)
- Elisa Ferraro
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Lidia Pozhidaeva
- School of Biomedical Engineering and Imaging Science, King's College London, London, UK
| | - David S Pitcher
- National Heart and Lung Institute, Imperial College London, London, UK
| | | | - Jia Han Benjamin Koh
- School of Biomedical Engineering and Imaging Science, King's College London, London, UK
| | | | - Oleg Aslanidi
- School of Biomedical Engineering and Imaging Science, King's College London, London, UK
| | - Julia Gorelik
- National Heart and Lung Institute, Imperial College London, London, UK.
| | - Fu Siong Ng
- National Heart and Lung Institute, Imperial College London, London, UK.
| |
Collapse
|
12
|
Rusiecka OM, Montgomery J, Morel S, Batista-Almeida D, Van Campenhout R, Vinken M, Girao H, Kwak BR. Canonical and Non-Canonical Roles of Connexin43 in Cardioprotection. Biomolecules 2020; 10:biom10091225. [PMID: 32842488 PMCID: PMC7563275 DOI: 10.3390/biom10091225] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/17/2020] [Accepted: 08/20/2020] [Indexed: 12/15/2022] Open
Abstract
Since the mid-20th century, ischemic heart disease has been the world’s leading cause of death. Developing effective clinical cardioprotection strategies would make a significant impact in improving both quality of life and longevity in the worldwide population. Both ex vivo and in vivo animal models of cardiac ischemia/reperfusion (I/R) injury are robustly used in research. Connexin43 (Cx43), the predominant gap junction channel-forming protein in cardiomyocytes, has emerged as a cardioprotective target. Cx43 posttranslational modifications as well as cellular distribution are altered during cardiac reperfusion injury, inducing phosphorylation states and localization detrimental to maintaining intercellular communication and cardiac conduction. Pre- (before ischemia) and post- (after ischemia but before reperfusion) conditioning can abrogate this injury process, preserving Cx43 and reducing cell death. Pre-/post-conditioning has been shown to largely rely on the presence of Cx43, including mitochondrial Cx43, which is implicated to play a major role in pre-conditioning. Posttranslational modifications of Cx43 after injury alter the protein interactome, inducing negative protein cascades and altering protein trafficking, which then causes further damage post-I/R injury. Recently, several peptides based on the Cx43 sequence have been found to successfully diminish cardiac injury in pre-clinical studies.
Collapse
Affiliation(s)
- Olga M. Rusiecka
- Department of Pathology and Immunology, University of Geneva, CH-1211 Geneva, Switzerland; (O.M.R.); (J.M.); (S.M.)
| | - Jade Montgomery
- Department of Pathology and Immunology, University of Geneva, CH-1211 Geneva, Switzerland; (O.M.R.); (J.M.); (S.M.)
| | - Sandrine Morel
- Department of Pathology and Immunology, University of Geneva, CH-1211 Geneva, Switzerland; (O.M.R.); (J.M.); (S.M.)
| | - Daniela Batista-Almeida
- Univ Coimbra, Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal; (D.B.-A.); (H.G.)
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3000-548 Coimbra, Portugal
- Clinical Academic Centre of Coimbra (CACC), 3000-548 Coimbra, Portugal
| | - Raf Van Campenhout
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, 1090 Brussels, Belgium; (R.V.C.); (M.V.)
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, 1090 Brussels, Belgium; (R.V.C.); (M.V.)
| | - Henrique Girao
- Univ Coimbra, Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal; (D.B.-A.); (H.G.)
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3000-548 Coimbra, Portugal
- Clinical Academic Centre of Coimbra (CACC), 3000-548 Coimbra, Portugal
| | - Brenda R. Kwak
- Department of Pathology and Immunology, University of Geneva, CH-1211 Geneva, Switzerland; (O.M.R.); (J.M.); (S.M.)
- Correspondence:
| |
Collapse
|
13
|
Losenkova K, Zuccarini M, Karikoski M, Laurila J, Boison D, Jalkanen S, Yegutkin GG. Compartmentalization of adenosine metabolism in cancer cells and its modulation during acute hypoxia. J Cell Sci 2020; 133:jcs241463. [PMID: 32317394 PMCID: PMC10681022 DOI: 10.1242/jcs.241463] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 04/02/2020] [Indexed: 12/20/2022] Open
Abstract
Extracellular adenosine mediates diverse anti-inflammatory, angiogenic and vasoactive effects, and has become an important therapeutic target for cancer, which has been translated into clinical trials. This study was designed to comprehensively assess adenosine metabolism in prostate and breast cancer cells. We identified cellular adenosine turnover as a complex cascade, comprising (1) the ectoenzymatic breakdown of ATP via sequential ecto-nucleotide pyrophosphatase/phosphodiesterase-1 (NPP1, officially known as ENPP1), ecto-5'-nucleotidase (CD73, also known as NT5E), and adenosine deaminase reactions, and ATP re-synthesis through a counteracting adenylate kinase and members of the nucleoside diphosphate kinase (NDPK, also known as NME/NM23) family; (2) the uptake of nucleotide-derived adenosine via equilibrative nucleoside transporters; and (3) the intracellular adenosine phosphorylation into ATP by adenosine kinase and other nucleotide kinases. The exposure of cancer cells to 1% O2 for 24 h triggered an ∼2-fold upregulation of CD73, without affecting nucleoside transporters, adenosine kinase activity and cellular ATP content. The ability of adenosine to inhibit the tumor-initiating potential of breast cancer cells via a receptor-independent mechanism was confirmed in vivo using a xenograft mouse model. The existence of redundant pathways controlling extracellular and intracellular adenosine provides a sufficient justification for reexamination of the current concepts of cellular purine homeostasis and signaling in cancer.This article has an associated First Person interview with the first author of the paper.
Collapse
Affiliation(s)
| | - Mariachiara Zuccarini
- MediCity Research Laboratory, University of Turku, 20520 Turku, Finland
- Department of Medical, Oral and Biotechnological Sciences, 'G. D'Annunzio' University of Chieti-Pescara, 66100 Chieti, Italy
| | - Marika Karikoski
- MediCity Research Laboratory, University of Turku, 20520 Turku, Finland
| | - Juha Laurila
- MediCity Research Laboratory, University of Turku, 20520 Turku, Finland
| | - Detlev Boison
- Department of Neurosurgery, Robert Wood Johnson and New Jersey Medical Schools, Rutgers University, Piscataway, NJ 08854, USA
| | - Sirpa Jalkanen
- MediCity Research Laboratory, University of Turku, 20520 Turku, Finland
| | | |
Collapse
|
14
|
George SA, Hoeker G, Calhoun PJ, Entz M, Raisch TB, King DR, Khan M, Baker C, Gourdie RG, Smyth JW, Nielsen MS, Poelzing S. Modulating cardiac conduction during metabolic ischemia with perfusate sodium and calcium in guinea pig hearts. Am J Physiol Heart Circ Physiol 2019; 316:H849-H861. [PMID: 30707595 DOI: 10.1152/ajpheart.00083.2018] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We previously demonstrated that altering extracellular sodium (Nao) and calcium (Cao) can modulate a form of electrical communication between cardiomyocytes termed "ephaptic coupling" (EpC), especially during loss of gap junction coupling. We hypothesized that altering Nao and Cao modulates conduction velocity (CV) and arrhythmic burden during ischemia. Electrophysiology was quantified by optically mapping Langendorff-perfused guinea pig ventricles with modified Nao (147 or 155 mM) and Cao (1.25 or 2.0 mM) during 30 min of simulated metabolic ischemia (pH 6.5, anoxia, aglycemia). Gap junction-adjacent perinexal width ( WP), a candidate cardiac ephapse, and connexin (Cx)43 protein expression and Cx43 phosphorylation at S368 were quantified by transmission electron microscopy and Western immunoblot analysis, respectively. Metabolic ischemia slowed CV in hearts perfused with 147 mM Nao and 2.0 mM Cao; however, theoretically increasing EpC with 155 mM Nao was arrhythmogenic, and CV could not be measured. Reducing Cao to 1.25 mM expanded WP, as expected during ischemia, consistent with reduced EpC, but attenuated CV slowing while delaying arrhythmia onset. These results were further supported by osmotically reducing WP with albumin, which exacerbated CV slowing and increased early arrhythmias during ischemia, whereas mannitol expanded WP, permitted conduction, and delayed the onset of arrhythmias. Cx43 expression patterns during the various interventions insufficiently correlated with observed CV changes and arrhythmic burden. In conclusion, decreasing perfusate calcium during metabolic ischemia enhances perinexal expansion, attenuates conduction slowing, and delays arrhythmias. Thus, perinexal expansion may be cardioprotective during metabolic ischemia. NEW & NOTEWORTHY This study demonstrates, for the first time, that modulating perfusate ion composition can alter cardiac electrophysiology during simulated metabolic ischemia.
Collapse
Affiliation(s)
- Sharon A George
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University , Blacksburg, Virginia.,Center for Heart and Reparative Medicine Research, Virginia Tech Carilion Research Institute , Roanoke, Virginia
| | - Gregory Hoeker
- Center for Heart and Reparative Medicine Research, Virginia Tech Carilion Research Institute , Roanoke, Virginia
| | - Patrick J Calhoun
- Center for Heart and Reparative Medicine Research, Virginia Tech Carilion Research Institute , Roanoke, Virginia.,Department of Biological Sciences, Virginia Polytechnic Institute and State University , Blacksburg, Virginia
| | - Michael Entz
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University , Blacksburg, Virginia.,Center for Heart and Reparative Medicine Research, Virginia Tech Carilion Research Institute , Roanoke, Virginia
| | - Tristan B Raisch
- Center for Heart and Reparative Medicine Research, Virginia Tech Carilion Research Institute , Roanoke, Virginia.,Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University , Blacksburg, Virginia
| | - D Ryan King
- Center for Heart and Reparative Medicine Research, Virginia Tech Carilion Research Institute , Roanoke, Virginia.,Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University , Blacksburg, Virginia
| | - Momina Khan
- Department of Human Food Nutrition and Exercise, Virginia Polytechnic Institute and State University , Blacksburg, Virginia
| | - Chandra Baker
- Center for Heart and Reparative Medicine Research, Virginia Tech Carilion Research Institute , Roanoke, Virginia
| | - Robert G Gourdie
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University , Blacksburg, Virginia.,Center for Heart and Reparative Medicine Research, Virginia Tech Carilion Research Institute , Roanoke, Virginia
| | - James W Smyth
- Center for Heart and Reparative Medicine Research, Virginia Tech Carilion Research Institute , Roanoke, Virginia.,Department of Biological Sciences, Virginia Polytechnic Institute and State University , Blacksburg, Virginia
| | - Morten S Nielsen
- Department of Biomedical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Steven Poelzing
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University , Blacksburg, Virginia.,Center for Heart and Reparative Medicine Research, Virginia Tech Carilion Research Institute , Roanoke, Virginia.,Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University , Blacksburg, Virginia
| |
Collapse
|
15
|
Visonà SD, Benati D, Monti MC, Galiè M, Andrello L, Frontini A, Osculati A. Diagnosis of sudden cardiac death due to early myocardial ischemia: An ultrastructural and immunohistochemical study. Eur J Histochem 2018; 62:2866. [PMID: 29943950 PMCID: PMC6038110 DOI: 10.4081/ejh.2018.2866] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 02/13/2018] [Accepted: 02/20/2018] [Indexed: 01/06/2023] Open
Abstract
The aim of this post-mortem ultrastructural and immunohistochemical study is to explore the characteristics of acute myocardial ischemia in the context of sudden death, using the combination of two different methods, both more insightful than ordinary histology. Transmission electron microscopy and immunohistochemistry, in addition to the traditional histology, were applied to study human heart specimens collected during forensic autopsies. The whole series was sub-grouped into cases (n=17) and controls (N=10). The control group consisted of unnatural death with a short agonal period (immediately lethal injuries). Heart samples of the two cohorts of subjects were prepared for electron microscopy. On the other hand, each specimen, formalin fixed and paraffin embedded, was stained with haematoxylin and eosin and immunoreacted with the following primary antibodies: anti-Fibronectin, anti- Connexin-43, anti-npCx43 (dephosphorylated form of Connexin43), anti-Zonula occludens-1. Immunopositivity for each marker in the myocardium was semi-quantitatively graded. Electron microscopy revealed a number of interesting differences, statistically significant, between acute myocardial ischemia and controls, regarding the morphology of nucleus, mitochondria and intercellular junctions. By immunohistochemistry, fibronectin was found to be increased in the extracellular matrix of the acute myocardial ischemia cases, with a statistically significant difference compared to the controls. Connexin 43 staining disclosed a slight increase (not statistically significant) in the cytoplasm of acute myocardial ischemia cases compared to the controls, whereas no significant differences were seen between cases and controls at intercellular junctions. npCx43 showed an evident difference of intensity and pattern (even though not statistically significant) in cases compared to controls and overall this difference was more evident in the cytoplasm. Zonula occludens 1, described as an important marker for functional modification of cardiac muscle fibers, resulted negative or very weak in the vast majority of both cases and controls. The present study attempts to simultaneously apply electron microscopy and immunohistochemistry, in order to figure out the morphological changes that might lead to pathological processes underlying the sudden, unexpected death due to acute myocardial ischemia, and consequently to find useful diagnostic markers of very early ischemic injury. Both methods showed significant differences between acute myocardial ischemia and controls, regarding, overall nuclei, mitochondria, and intercellular junctions.
Collapse
|
16
|
Endothelial cells cope with hypoxia-induced depletion of ATP via activation of cellular purine turnover and phosphotransfer networks. Biochim Biophys Acta Mol Basis Dis 2018. [PMID: 29514048 DOI: 10.1016/j.bbadis.2018.03.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Intravascular ATP and adenosine have emerged as important regulators of endothelial barrier function, vascular remodeling and neovascularization at various pathological states, including hypoxia, inflammation and oxidative stress. By using human umbilical vein endothelial cells (HUVEC) and bovine vasa vasorum endothelial cells (VVEC) as representatives of macro- and microvessel phenotypes, this study was undertaken to evaluate cellular mechanisms contributing to physiological adaptation of vascular endothelium to hypoxia, with a particular emphasis on ectoenzymatic purine-converting activities and their link to intracellular ATP homeostasis and signaling pathways. Nucleoside triphosphate diphosphohydrolase-1 (NTPDase1/CD39), ecto-5'-nucleotidase/CD73 and ecto-adenylate kinase activities were determined by thin-layer chromatography (TLC) with 3H-labelled nucleotide substrates. Exposure of HUVEC and VVEC to 1% O2 for 4-24 h triggered rather moderate activation of ATP breakdown into adenosine via the CD39-CD73 axis. Additional TLC analysis of salvage pathways revealed the enhanced ability of hypoxic HUVEC to convert cell-incorporated [3H]adenosine into [3H]ADP/ATP. Furthermore, following a period of hypoxia, HUVEC underwent concurrent changes in intracellular signaling manifested in the depletion of putative ATP stores and targeted up-regulation of phospho-p53, p70S6K/mTOR and other tyrosine kinases. The revealed complex implication of both extrinsic and intrinsic mechanisms into a tuned hypoxia-induced control of purine homeostasis and signaling may open up further research for the development of pharmacological treatments to improve endothelial cell function under disease conditions associated with a loss of cellular ATP during oxygen deprivation.
Collapse
|
17
|
Leybaert L, Lampe PD, Dhein S, Kwak BR, Ferdinandy P, Beyer EC, Laird DW, Naus CC, Green CR, Schulz R. Connexins in Cardiovascular and Neurovascular Health and Disease: Pharmacological Implications. Pharmacol Rev 2017; 69:396-478. [PMID: 28931622 PMCID: PMC5612248 DOI: 10.1124/pr.115.012062] [Citation(s) in RCA: 171] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Connexins are ubiquitous channel forming proteins that assemble as plasma membrane hemichannels and as intercellular gap junction channels that directly connect cells. In the heart, gap junction channels electrically connect myocytes and specialized conductive tissues to coordinate the atrial and ventricular contraction/relaxation cycles and pump function. In blood vessels, these channels facilitate long-distance endothelial cell communication, synchronize smooth muscle cell contraction, and support endothelial-smooth muscle cell communication. In the central nervous system they form cellular syncytia and coordinate neural function. Gap junction channels are normally open and hemichannels are normally closed, but pathologic conditions may restrict gap junction communication and promote hemichannel opening, thereby disturbing a delicate cellular communication balance. Until recently, most connexin-targeting agents exhibited little specificity and several off-target effects. Recent work with peptide-based approaches has demonstrated improved specificity and opened avenues for a more rational approach toward independently modulating the function of gap junctions and hemichannels. We here review the role of connexins and their channels in cardiovascular and neurovascular health and disease, focusing on crucial regulatory aspects and identification of potential targets to modify their function. We conclude that peptide-based investigations have raised several new opportunities for interfering with connexins and their channels that may soon allow preservation of gap junction communication, inhibition of hemichannel opening, and mitigation of inflammatory signaling.
Collapse
Affiliation(s)
- Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Paul D Lampe
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Stefan Dhein
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Brenda R Kwak
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Peter Ferdinandy
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Eric C Beyer
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Dale W Laird
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Christian C Naus
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Colin R Green
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Rainer Schulz
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| |
Collapse
|
18
|
Kardiale „gap junctions“. ZEITSCHRIFT FUR HERZ THORAX UND GEFASSCHIRURGIE 2017. [DOI: 10.1007/s00398-016-0106-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
19
|
Aghazadeh-Attari J, Sufian N, Fink-Gremmels J, Malekinejad H. Allopurinol attenuated the chemically-induced hypoxia (hypoxia-reoxygenation) injuries via down-regulation of the transcription factor HIF-1α in neuroblastoma cells. Biomed Pharmacother 2017. [DOI: 10.1016/j.biopha.2017.01.143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
|
20
|
Liu H, Li XZ, Peng M, Ji W, Zhao L, Li L, Zhang L, Si JQ, Ma KT. Role of gap junctions in the contractile response to agonists in the mesenteric resistance artery of rats with acute hypoxia. Mol Med Rep 2017; 15:1823-1831. [DOI: 10.3892/mmr.2017.6188] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 12/21/2016] [Indexed: 11/06/2022] Open
|
21
|
Connexin 43 and Mitochondria in Cardiovascular Health and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 982:227-246. [PMID: 28551790 DOI: 10.1007/978-3-319-55330-6_12] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Connexin 43 (Cx43) is the major connexin protein in ventricular cardiomyocytes. Six Cx43 proteins assemble into so-called hemichannels at the sarcolemma and opposing hemichannels form gap junctions, which allow the passage of small molecules and electrical current flow between adjacent cells. Apart from its localization at the plasma membrane, Cx43 is also present in cardiomyocyte mitochondria, where it is important for mitochondrial function in terms of oxygen consumption and potassium fluxes. The expression of gap junctional and mitochondrial Cx43 is altered under several pathophysiological conditions among them are hypertension, hypertrophy, hypercholesterolemia, ischemia/reperfusion injury, post-infarction remodeling, and heart failure. The present review will focus on the role of Cx43 in cardiovascular diseases and will highlight the importance of mitochondrial Cx43 in cardioprotection.
Collapse
|
22
|
Hou S, Shen PP, Zhao MM, Liu XP, Xie HY, Deng F, Feng JC. Mechanism of Mitochondrial Connexin43's Protection of the Neurovascular Unit under Acute Cerebral Ischemia-Reperfusion Injury. Int J Mol Sci 2016; 17:ijms17050679. [PMID: 27164087 PMCID: PMC4881505 DOI: 10.3390/ijms17050679] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 04/27/2016] [Accepted: 04/29/2016] [Indexed: 02/08/2023] Open
Abstract
We observed mitochondrial connexin43 (mtCx43) expression under cerebral ischemia-reperfusion (I/R) injury, analyzed its regulation, and explored its protective mechanisms. Wistar rats were divided into groups based on injections received before middle cerebral artery occlusion (MCAO). Cerebral infarction volume was detected by 2,3,5-triphenyltetrazolim chloride staining, and cell apoptosis was observed by transferase dUTP nick end labeling. We used transmission electron microscopy to observe mitochondrial morphology and determined superoxide dismutase (SOD) activity and malondialdehyde (MDA) content. MtCx43, p-mtCx43, protein kinase C (PKC), and p-PKC expression were detected by Western blot. Compared with those in the IR group, cerebral infarction volumes in the carbenoxolone (CBX) and diazoxide (DZX) groups were obviously smaller, and the apoptosis indices were down-regulated. Mitochondrial morphology was damaged after I/R, especially in the IR and 5-hydroxydecanoic acid (5-HD) groups. Similarly, decreased SOD activity and increased MDA were observed after MCAO; CBX, DZX, and phorbol-12-myristate-13-acetate (PMA) reduced mitochondrial functional injury. Expression of mtCx43 and p-mtCx43 and the p-Cx43/Cx43 ratio were significantly lower in the IR group than in the sham group. These abnormalities were ameliorated by CBX, DZX, and PMA. MtCx43 may protect the neurovascular unit from acute cerebral IR injury via PKC activation induced by mitoKATP channel agonists.
Collapse
Affiliation(s)
- Shuai Hou
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Ping-Ping Shen
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Ming-Ming Zhao
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Xiu-Ping Liu
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Hong-Yan Xie
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Fang Deng
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Jia-Chun Feng
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| |
Collapse
|
23
|
Joshi S, Wei J, Bishopric NH. A cardiac myocyte-restricted Lin28/let-7 regulatory axis promotes hypoxia-mediated apoptosis by inducing the AKT signaling suppressor PIK3IP1. Biochim Biophys Acta Mol Basis Dis 2015; 1862:240-51. [PMID: 26655604 DOI: 10.1016/j.bbadis.2015.12.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 11/02/2015] [Accepted: 12/01/2015] [Indexed: 12/14/2022]
Abstract
RATIONALE The let-7 family of microRNAs (miRs) regulates critical cell functions, including survival signaling, differentiation, metabolic control and glucose utilization. These functions may be important during myocardial ischemia. MiR-let-7 expression is under tight temporal and spatial control through multiple redundant mechanisms that may be stage-, isoform- and tissue-specific. OBJECTIVE To determine the mechanisms and functional consequences of miR-let-7 regulation by hypoxia in the heart. METHODS AND RESULTS MiR-let-7a, -7c and -7g were downregulated in the adult mouse heart early after coronary occlusion, and in neonatal rat ventricular myocytes subjected to hypoxia. Let-7 repression did not require glucose depletion, and occurred at a post-transcriptional level. Hypoxia also induced the RNA binding protein Lin28, a negative regulator of let-7. Hypoxia ineither induced Lin28 nor repressed miR-let-7 in cardiac fibroblasts. Both changes were abrogated by treatment with the histone deacetylase inhibitor trichostatin A. Restoration of let-7g to hypoxic myocytes and to ischemia-reperfused mouse hearts in vivo via lentiviral transduction potentiated the hypoxia-induced phosphorylation and activation of Akt, and prevented hypoxia-dependent caspase activation and death. Mechanistically, phosphatidyl inositol 3-kinase interacting protein 1 (Pik3ip1), a negative regulator of PI3K, was identified as a novel target of miR-let-7 by a crosslinking technique showing that miR-let-7g specifically targets Pik3ip1 to the cardiac myocyte Argonaute complex RISC. Finally, in non-failing and failing human myocardium, we found specific inverse relationships between Lin28 and miR-let-7g, and between miR-let-7g and PIK3IP1. CONCLUSION A conserved hypoxia-responsive Lin28-miR-let-7-Pik3ip1 regulatory axis is specific to cardiac myocytes and promotes apoptosis during myocardial ischemic injury.
Collapse
Affiliation(s)
- Shaurya Joshi
- Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States; Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Jianqin Wei
- Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Nanette H Bishopric
- Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States; Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, United States; Department of Pediatrics, University of Miami Miller School of Medicine, Miami, FL, United States.
| |
Collapse
|
24
|
Schulz R, Görge PM, Görbe A, Ferdinandy P, Lampe PD, Leybaert L. Connexin 43 is an emerging therapeutic target in ischemia/reperfusion injury, cardioprotection and neuroprotection. Pharmacol Ther 2015; 153:90-106. [PMID: 26073311 DOI: 10.1016/j.pharmthera.2015.06.005] [Citation(s) in RCA: 163] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 05/29/2015] [Indexed: 12/22/2022]
Abstract
Connexins are widely distributed proteins in the body that are crucially important for heart and brain functions. Six connexin subunits form a connexon or hemichannel in the plasma membrane. Interactions between two hemichannels in a head-to-head arrangement result in the formation of a gap junction channel. Gap junctions are necessary to coordinate cell function by passing electrical current flow between heart and nerve cells or by allowing exchange of chemical signals and energy substrates. Apart from its localization at the sarcolemma of cardiomyocytes and brain cells, connexins are also found in the mitochondria where they are involved in the regulation of mitochondrial matrix ion fluxes and respiration. Connexin expression is affected by age and gender as well as several pathophysiological alterations such as hypertension, hypertrophy, diabetes, hypercholesterolemia, ischemia, post-myocardial infarction remodeling or heart failure, and post-translationally connexins are modified by phosphorylation/de-phosphorylation and nitros(yl)ation which can modulate channel activity. Using knockout/knockin technology as well as pharmacological approaches, one of the connexins, namely connexin 43, has been identified to be important for cardiac and brain ischemia/reperfusion injuries as well as protection from it. Therefore, the current review will focus on the importance of connexin 43 for irreversible injury of heart and brain tissues following ischemia/reperfusion and will highlight the importance of connexin 43 as an emerging therapeutic target in cardio- and neuroprotection.
Collapse
Affiliation(s)
- Rainer Schulz
- Institut für Physiologie, JustusLiebig Universität Giessen, Gießen, Germany.
| | | | - Anikó Görbe
- Cardiovascular Research Group, Department of Biochemistry, Faculty of Medicine, University of Szeged, Hungary; Pharmahungary Group, Szeged, Hungary
| | - Péter Ferdinandy
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary; Pharmahungary Group, Szeged, Hungary
| | - Paul D Lampe
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Luc Leybaert
- Physiology Group, Department Basic Medical Sciences, Ghent University, Belgium
| |
Collapse
|
25
|
Kang M, Lin N, Li C, Meng Q, Zheng Y, Yan X, Deng J, Ou Y, Zhang C, He J, Luo D. Cx43 phosphorylation on S279/282 and intercellular communication are regulated by IP3/IP3 receptor signaling. Cell Commun Signal 2014; 12:58. [PMID: 25262337 PMCID: PMC4195880 DOI: 10.1186/s12964-014-0058-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 09/11/2014] [Indexed: 11/17/2022] Open
Abstract
Background Inositol 1,4,5-trisphosphate receptor (IP3R) plays a pivotal role in the Ca2+ release process in a variety of cell types. Additionally, IP3R is distributed in ventricular intercalated discs, but its function(s) in this particular site remains unknown. Connexin (Cx43), the predominant gap junction (GJ) protein in ventricular myocardium, is linked to several signaling pathways that regulate Cx43 properties by (de)phosphorylation on multiple residues. Here, we investigated the regulatory role of IP3R in cell-cell communication and the mechanism(s) underlying this effect. Results In neonatal rat and adult mouse ventricular myocytes IP3R co-localized and co-immunoprecipitated with Cx43 in GJ plaques detected by immunostaining and western blot assays. Blocking IP3R with antagonists or silencing pan-IP3R expression with shRNA hindered the 6-carboxyfluorescein (6-CFDA) diffusion through GJs and desynchronized Ca2+ transients among confluent neonatal myocytes in culture, whereas stimulation of IP3R with IP3 ester or ATP exerted the opposite effect. Likewise, 6-CFDA propagation through GJs was modulated by IP3R activation or inhibition in cell pairs of isolated adult cardiomyocytes. Furthermore, IP3R activation or IP3R suppression promoted or suppressed, respectively, Cx43 phosphorylation on S279/282. Site-directed mutagenesis indicated that expression of a mutant Cx43-S282A (alanine) inhibited S279/282 phosphorylation and GJ permeability, while the S279A mutant showed the opposite effect in ventricular myocytes. Expression of these mutants in HEK293 cells revealed that cells with a dual S279/282 mutation failed to express exogenous Cx43, whereas cells with a single S279 or S282 mutation displayed Cx43 overexpression with increased phosphorylation of S279/282 and promotion of intercellular communication. Conclusions These results demonstrated, for the first time, that IP3R physically interacts with Cx43 and participates in the regulation of Cx43 phosphorylation on S279/282, thereby affecting GJ intercellular communication in ventricular myocytes. Electronic supplementary material The online version of this article (doi:10.1186/s12964-014-0058-6) contains supplementary material, which is available to authorized users.
Collapse
|
26
|
Bejarano E, Yuste A, Patel B, Stout RF, Spray DC, Cuervo AM. Connexins modulate autophagosome biogenesis. Nat Cell Biol 2014; 16:401-14. [PMID: 24705551 PMCID: PMC4008708 DOI: 10.1038/ncb2934] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 02/14/2014] [Indexed: 12/17/2022]
Abstract
The plasma membrane contributes to the formation of autophagosomes, the double-membrane vesicles that sequester cytosolic cargo and deliver it to lysosomes for degradation during autophagy. In this study, we have identified a regulatory role for connexins (Cx), the main components of plasma membrane gap junctions, in autophagosome formation. We have found that plasma-membrane-localized Cx proteins constitutively downregulate autophagy through a direct interaction with several autophagy-related proteins involved in the initial steps of autophagosome formation, such as Atg16 and components of the PI(3)K autophagy initiation complex (Vps34, Beclin-1 and Vps15). On nutrient starvation, this inhibitory effect is released by the arrival of Atg14 to the Cx-Atg complex. This promotes the internalization of Cx-Atg along with Atg9, which is also recruited to the plasma membrane in response to starvation. Maturation of the Cx-containing pre-autophagosomes into autophagosomes leads to degradation of these endogenous inhibitors, allowing for sustained activation of autophagy.
Collapse
Affiliation(s)
- Eloy Bejarano
- Department of Developmental and Molecular Biology and Institute for Aging Studies, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Andrea Yuste
- Department of Developmental and Molecular Biology and Institute for Aging Studies, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Bindi Patel
- Department of Developmental and Molecular Biology and Institute for Aging Studies, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Randy F. Stout
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - David C. Spray
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Ana Maria Cuervo
- Department of Developmental and Molecular Biology and Institute for Aging Studies, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| |
Collapse
|
27
|
Billaud M, Lohman AW, Johnstone SR, Biwer LA, Mutchler S, Isakson BE. Regulation of cellular communication by signaling microdomains in the blood vessel wall. Pharmacol Rev 2014; 66:513-69. [PMID: 24671377 DOI: 10.1124/pr.112.007351] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
It has become increasingly clear that the accumulation of proteins in specific regions of the plasma membrane can facilitate cellular communication. These regions, termed signaling microdomains, are found throughout the blood vessel wall where cellular communication, both within and between cell types, must be tightly regulated to maintain proper vascular function. We will define a cellular signaling microdomain and apply this definition to the plethora of means by which cellular communication has been hypothesized to occur in the blood vessel wall. To that end, we make a case for three broad areas of cellular communication where signaling microdomains could play an important role: 1) paracrine release of free radicals and gaseous molecules such as nitric oxide and reactive oxygen species; 2) role of ion channels including gap junctions and potassium channels, especially those associated with the endothelium-derived hyperpolarization mediated signaling, and lastly, 3) mechanism of exocytosis that has considerable oversight by signaling microdomains, especially those associated with the release of von Willebrand factor. When summed, we believe that it is clear that the organization and regulation of signaling microdomains is an essential component to vessel wall function.
Collapse
Affiliation(s)
- Marie Billaud
- Dept. of Molecular Physiology and Biophysics, University of Virginia School of Medicine, PO Box 801394, Charlottesville, VA 22902.
| | | | | | | | | | | |
Collapse
|
28
|
Dynamic alterations of connexin43, matrix metalloproteinase-2 and tissue inhibitor of matrix metalloproteinase-2 during ventricular fibrillation in canine. Mol Cell Biochem 2014; 391:259-66. [PMID: 24639125 DOI: 10.1007/s11010-014-2012-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 02/28/2014] [Indexed: 10/25/2022]
Abstract
The aim of this study is to investigate the dynamic alterations of cardiac connexin 43 (Cx43), matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) in the setting of different ventricular fibrillation (VF) duration. In this study, thirty-two dogs were randomly divided into sham control group, 8-min VF group, 12-min VF group, and 30-min VF group. Cx43 and phosphorylated Cx43 (p-Cx43) in tissues were detected by western blot and immunofluorescence analysis. MMP-2 and TIMP-2 were detected by western blot and immunohistochemistry analysis. The results showed that Cx43 levels in three VF groups were significantly decreased compared with sham control group. p-Cx43 levels in 12-min and 30-min VF groups were significantly reduced compared with sham control group. The ratio of p-Cx43/Cx43 was also decreased in VF groups. Compared with sham controls, no significant difference was observed between the sham control group and 8-min VF group in MMP-2 level, but MMP-2 level increased in 12-min and 30-min VF groups. The ratios of MMP-2/TIMP-2 were higher in VF groups, and were correlated with the duration of VF. A remarkable correlation was observed between the ratio of p-Cx43/Cx43 and MMP-2/TIMP-2 (r = -0.93, P < 0.01). In conclusion, the alteration of Cx43 and/or p-Cx43 levels and the imbalance of MMP-2 and TIMP-2 may contribute to the initiation and/or persistence of VF. Maneuvers managed to modulate Cx43 level or normalize the balance of MMP-2/TIMP-2 are promising to ameliorate prognosis of VF.
Collapse
|
29
|
Wu X, Huang W, Luo G, Alain LA. Hypoxia induces connexin 43 dysregulation by modulating matrix metalloproteinases via MAPK signaling. Mol Cell Biochem 2013; 384:155-62. [PMID: 24002703 PMCID: PMC3825321 DOI: 10.1007/s11010-013-1793-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 08/23/2013] [Indexed: 11/30/2022]
Abstract
Connexin 43 (Cx43) is a major structural protein found in the gap junctions of the ventricular myocardium and a major determinant of its electrical properties. The effects of matrix metalloproteinases (MMPs), the mitogen-activated protein kinase (MAPK) signaling pathway, transcription factor NF-kB, and activator protein-1 (AP-1)/c-Jun on the regulation of Cx43 gene expression in H9c2 cardiomyocytes were assessed. The MAPK signaling pathway (MEK/ERK1/2 and PI3K) and transcription factors NF-kB and AP-1/c-Jun were inhibited, then Cx43 expression was assessed using Western blot analysis, and MMP-9 activity was assessed using gelatin zymography. Hypoxia decreased the Cx43 protein level by approximately 30-50 %. Doxycycline (10 μg/mL), an inhibitor of MMP, markedly attenuated the hypoxia-induced downregulation of Cx43 protein expression at 6 h. The hypoxia-induced decrease in Cx43 protein expression was significantly reversed by U0126 (10 μM), a MEK/ERK1/2 inhibitor, at 6 and 12 h; LY294002 (30 μM), a PI3K inhibitor, downregulated Cx43 expression. Hypoxia-induced MMP-9 activation was inhibited by treatment with LY294002, U0126, and, most especially, U0126. JSH-23 (30 μM), an NF-kB inhibitor, and SP600125 (10 μM), an AP-1/c-Jun inhibitor, attenuated the loss of Cx43. These results suggest that MAPK signaling and the activities NF-kB and MMPs play an important roles in the regulation of Cx43 expression.
Collapse
Affiliation(s)
- Xianghong Wu
- Department of Cardiology, First Affiliated Hospital, Guangxi Medical University, Nanning, People's Republic of China
| | | | | | | |
Collapse
|
30
|
Huke S, Venkataraman R, Faggioni M, Bennuri S, Hwang HS, Baudenbacher F, Knollmann BC. Focal energy deprivation underlies arrhythmia susceptibility in mice with calcium-sensitized myofilaments. Circ Res 2013; 112:1334-44. [PMID: 23532597 DOI: 10.1161/circresaha.113.301055] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
RATIONALE The Ca(2+) sensitivity of the myofilaments is increased in hypertrophic cardiomyopathy and other heart diseases and may contribute to a higher risk for sudden cardiac death. Ca(2+) sensitization increases susceptibility to reentrant ventricular tachycardia in animal models, but the underlying mechanism is unknown. OBJECTIVE To investigate how myofilament Ca(2+) sensitization creates reentrant arrhythmia susceptibility. METHODS AND RESULTS Using hypertrophic cardiomyopathy mouse models (troponinT-I79N) and a Ca(2+) sensitizing drug (EMD57033), here we identify focal energy deprivation as a direct consequence of myofilament Ca(2+) sensitization. To detect ATP depletion and thus energy deprivation, we measured accumulation of dephosphorylated Connexin 43 (Cx43) isoform P0 and AMP kinase activation by Western blotting and immunostaining. No differences were detected between groups at baseline, but regional accumulation of Connexin 43 isoform P0 occurred within minutes in all Ca(2+)-sensitized hearts, in vivo after isoproterenol challenge and in isolated hearts after rapid pacing. Lucifer yellow dye spread demonstrated reduced gap junctional coupling in areas with Connexin 43 isoform P0 accumulation. Optical mapping revealed that selectively the transverse conduction velocity was slowed and anisotropy increased. Myofilament Ca(2+) desensitization with blebbistatin prevented focal energy deprivation, transverse conduction velocity slowing, and the reentrant ventricular arrhythmias. CONCLUSIONS Myofilament Ca(2+) sensitization rapidly leads to focal energy deprivation and reduced intercellular coupling during conditions that raise arrhythmia susceptibility. This is a novel proarrhythmic mechanism that can increase arrhythmia susceptibility in structurally normal hearts within minutes and may, therefore, contribute to sudden cardiac death in diseases with increased myofilament Ca(2+) sensitivity.
Collapse
Affiliation(s)
- Sabine Huke
- Division of Clinical Pharmacology, Vanderbilt University, Nashville, TN, USA.
| | | | | | | | | | | | | |
Collapse
|
31
|
Lee TM, Lin CC, Lien HY, Chen CC. K ATP channel agonists preserve connexin43 protein in infarcted rats by a protein kinase C-dependent pathway. J Cell Mol Med 2012; 16:776-88. [PMID: 21692984 PMCID: PMC3822848 DOI: 10.1111/j.1582-4934.2011.01366.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Downward remodelling of gap junctional proteins between myocytes may trigger ventricular arrhythmia after myocardial infarction. We have demonstrated that ATP-sensitive potassium (KATP) channel agonists attenuated post-infarction arrhythmias. However, the involved mechanisms remain unclear. The purpose of this study was to determine whether KATP channel agonists can attenuate arrhythmias through preserving protein kinase C (PKC)-–dependent connexin43 level after myocardial infarction. Male Wistar rats after ligating coronary artery were randomized to either vehicle, nicorandil, pinacidil, glibenclamide or a combination of nicorandil and glibenclamide or pinacidil and glibenclamide for 4 weeks. To elucidate the role of PKC in the modulation of connexin43 level, carbachol and myristoylated PKC V1–2 peptide were also assessed. Myocardial connexin43 level was significantly decreased in vehicle-treated infarcted rats compared with sham. Attenuated connexin43 level was blunted after administering KATP channel agonists, assessed by immunofluorescent analysis, Western blotting, and real-time quantitative reverse transcription-PCR of connexin43. Arrhythmic scores during programmed stimulation in the KATP channel agonists-treated rats were significantly lower than those treated with vehicle. The beneficial effects of KATP channel agonists were blocked by either glibenclamide or 5-hydroxydecanoate. Addition of the PKC activator, phorbol 12-myristate 13-acetate and the specific PKC agonist, carbachol, blocked the effects of nicorandil on connexin43 phosphorylation and dye permeability. The specific PKC antagonist, myristoylated PKC V1–2 peptide, did not have additional beneficial effects on connexin43 phosphorylation compared with rats treated with nicorandil alone. Chronic use of KATP channel agonists after infarction, resulting in enhanced connexin43 level through a PKC-dependent pathway, may attenuate the arrhythmogenic response to programmed electrical stimulation.
Collapse
Affiliation(s)
- Tsung-Ming Lee
- Department of Medicine, Cardiology Section, Taipei Medical University and Chi-Mei Medical Center, Tainan, Taiwan.
| | | | | | | |
Collapse
|
32
|
Chen VC, Gouw JW, Naus CC, Foster LJ. Connexin multi-site phosphorylation: mass spectrometry-based proteomics fills the gap. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:23-34. [PMID: 22421184 DOI: 10.1016/j.bbamem.2012.02.028] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 02/19/2012] [Accepted: 02/28/2012] [Indexed: 10/28/2022]
Abstract
Connexins require an integrated network for protein synthesis, assembly, gating, internalization, degradation and feedback control that are necessary to regulate the biosynthesis, and turnover of gap junction channels. At the most fundamental level, the introduction of sequence-altering, modifications introduces changes in protein conformation, activity, charge, stability and localization. Understanding the sites, patterns and magnitude of protein post-translational modification, including phosphorylation, is absolutely critical. Historically, the examination of connexin phosphorylation has been placed within the context that one or small number of sites of modification strictly corresponds to one molecular function. However, the release of high-profile proteomic datasets appears to challenge this dogma by demonstrating connexins undergo multiple levels of multi-site phosphorylation. With the growing prominence of mass spectrometry in biology and medicine, we are now getting a glimpse of the richness of connexin phosphate signals. Having implications to health and disease, this review provides an overview of technologies in the context of targeted and discovery proteomics, and further discusses how these techniques are being applied to "fill the gaps" in understanding of connexin post-translational control. This article is part of a Special Issue entitled: The Communicating junctions, roles and dysfunctions.
Collapse
Affiliation(s)
- Vincent C Chen
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada.
| | | | | | | |
Collapse
|
33
|
Márquez-Rosado L, Solan JL, Dunn CA, Norris RP, Lampe PD. Connexin43 phosphorylation in brain, cardiac, endothelial and epithelial tissues. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1985-92. [PMID: 21819962 DOI: 10.1016/j.bbamem.2011.07.028] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Revised: 07/14/2011] [Accepted: 07/19/2011] [Indexed: 11/30/2022]
Abstract
Gap junctions, composed of proteins from the connexin family, allow for intercellular communication between cells in essentially all tissues. There are 21 connexin genes in the human genome and different tissues express different connexin genes. Most connexins are known to be phosphoproteins. Phosphorylation can regulate connexin assembly into gap junctions, gap junction turnover and channel gating. Given the importance of gap junctions in development, proliferation and carcinogenesis, regulation of gap junction phosphorylation in response to wounding, hypoxia and other tissue insults is proving to be critical for cellular response and return to homeostasis. Connexin43 (Cx43) is the most widely and highly expressed gap junction protein, both in cell culture models and in humans, thus more research has been done on it and more reagents to it are available. In particular, antibodies that can report Cx43 phosphorylation status have been created allowing temporal examination of specific phosphorylation events in vivo. This review is focused on the use of these antibodies in tissue in situ, predominantly looking at Cx43 phosphorylation in brain, heart, endothelium and epithelium with reference to other connexins where data is available. These data allow us to begin to correlate specific phosphorylation events with changes in cell and tissue function. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
Collapse
|
34
|
De Vuyst E, Boengler K, Antoons G, Sipido KR, Schulz R, Leybaert L. Pharmacological modulation of connexin-formed channels in cardiac pathophysiology. Br J Pharmacol 2011; 163:469-83. [PMID: 21265827 PMCID: PMC3101610 DOI: 10.1111/j.1476-5381.2011.01244.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 12/09/2010] [Accepted: 01/02/2011] [Indexed: 12/17/2022] Open
Abstract
Coordinated electrical activity in the heart is supported by gap junction channels located at the intercalated discs of cardiomyocytes. Impaired gap junctional communication between neighbouring cardiomyocytes contributes to the development of re-entry arrhythmias after myocardial ischaemia. Current antiarrhythmic therapy is hampered by a lack of efficiency and side effects, creating the need for a new generation of drugs. In this review, we focus on compounds that increase gap junctional communication, thereby increasing the conduction velocity and decreasing the risk of arrhythmias. Some of these compounds also inhibit connexin 43 (Cx43) hemichannels, thereby limiting adenosine triphosphate loss and volume overload following ischaemia/reperfusion, thus potentially increasing the survival of cardiomyocytes. The compounds discussed in this review are: (i) antiarrythmic peptide (AAP), AAP10, ZP123; (ii) GAP-134; (iii) RXP-E; and (vi) the Cx mimetic peptides Gap 26 and Gap 27. None of these compounds have effects on Na(+) , Ca(2+) and K(+) channels, and therefore have no proarrhythmic activity associated with currently available antiarrhythmic drugs. GAP-134, RXP-E, Gap 26 and Gap 27 are pharmalogical agents with a favorable clinical safety profile, as already confirmed in phase I clinical trials for GAP-134. These agents show an excellent promise for treatment of arrhythmias in patients with ischaemic cardiomyopathy.
Collapse
Affiliation(s)
- Elke De Vuyst
- Department of Basic Medical Sciences – Physiology group, Faculty of Medicine and Health Sciences, Ghent UniversityGhent, Belgium
| | - Kerstin Boengler
- Institut für Pathophysiologie, Zentrum für Innere Medizin, Universitätsklinikum EssenEssen, Germany
| | - Gudrun Antoons
- Department for Experimental Cardiology, O & N1, K.U.LeuvenLeuven, Belgium
| | - Karin R Sipido
- Department for Experimental Cardiology, O & N1, K.U.LeuvenLeuven, Belgium
| | - Rainer Schulz
- Institut für Physiologie, Justus-Liebig Universität GießenGießen, Germany
| | - Luc Leybaert
- Department of Basic Medical Sciences – Physiology group, Faculty of Medicine and Health Sciences, Ghent UniversityGhent, Belgium
| |
Collapse
|
35
|
Decrock E, Vinken M, Bol M, D'Herde K, Rogiers V, Vandenabeele P, Krysko DV, Bultynck G, Leybaert L. Calcium and connexin-based intercellular communication, a deadly catch? Cell Calcium 2011; 50:310-21. [PMID: 21621840 DOI: 10.1016/j.ceca.2011.05.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 05/03/2011] [Accepted: 05/05/2011] [Indexed: 10/18/2022]
Abstract
Ca(2+) is known as a universal messenger mediating a wide variety of cellular processes, including cell death. In fact, this ion has been proposed as the 'cell death master', not only at the intracellular but also at the intercellular level. The most direct form of intercellular spread of cell death is mediated by gap junction channels. These channels have been shown to propagate cell death as well as cell survival signals between the cytoplasm of neighbouring cells, reflecting the dual role of Ca(2+) signals, i.e. cell death versus survival. Its precursor, the unopposed hemichannel (half of a gap junction channel), has recently joined in as a toxic pore connecting the intracellular with the extracellular environment and allowing the passage of a range of substances. The biochemical nature of the so-called intercellular cell death molecule, transferred through gap junctions or released/taken up via hemichannels, remains elusive but several studies pinpoint Ca(2+) itself or its messenger inositol trisphosphate as the responsible masters in crime. Although direct evidence is still lacking, indirect data including Ca(2+) involvement in intercellular communication and cell death, and effects of intercellular communication on intracellular Ca(2+) homeostasis, support this hypothesis. In addition, hemichannels and their molecular building blocks, connexin or pannexin proteins, may exert their effects on Ca(2+)-dependent cell death at the intracellular level, independently from their channel functions. This review provides a cutting edge overview of the current knowledge and underscores the intimate connection between intercellular communication, Ca(2+) signalling and cell death.
Collapse
Affiliation(s)
- Elke Decrock
- Department of Basic Medical Sciences - Physiology Group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Alesutan I, Sopjani M, Munoz C, Fraser S, Kemp BE, Föller M, Lang F. Inhibition of Connexin 26 by the AMP-Activated Protein Kinase. J Membr Biol 2011; 240:151-8. [DOI: 10.1007/s00232-011-9353-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 02/22/2011] [Indexed: 01/19/2023]
|
37
|
Zhu H, Wang H, Zhang X, Hou X, Cao K, Zou J. Inhibiting N-cadherin-mediated adhesion affects gap junction communication in isolated rat hearts. Mol Cells 2010; 30:193-200. [PMID: 20803092 DOI: 10.1007/s10059-010-0107-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 05/19/2010] [Accepted: 05/27/2010] [Indexed: 12/21/2022] Open
Abstract
Cadherin-mediated adherens junctions is impaired concomitant with a decrease in connexin 43 (Cx43) in diseases or pathological processes. We have investigated the acute effects of adherens junction impairment in isolated rat hearts by introducing Ala-His-Ala-Val-Asp-NH(2) (AHAVD, a synthetic peptide) as a specific inhibitor of N-cadherin. Effect of AHAVD on N-cadherin mediated adhension was analyzed by Cardiomy-ocyte aggregation assay. Laser confocal microscopy showed disrupted cell-cell contacts in cultured neonatal cardiomyocytes co-incubated with 0.2 mM AHAVD. In isolated adult rat hearts, Cx43 was redistributed along the bilateral of cardiomyocytes from the intercalated discs and significant dephosphorylation of Cx43 on serine368 occurred concomitantly with decreased gap junction (GJ) function in dose dependent manner after 1 h perfusion with AHAVD. These results indicate that impairing cad-herin-mediated adhesion by AHAVD rapidly results in Cx43 redistribution and dephosphorylation of serine368, thereby impairing GJ communication function.
Collapse
Affiliation(s)
- Hongjun Zhu
- Department of Cardiology, First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, 210029, China
| | | | | | | | | | | |
Collapse
|
38
|
Huke S, Knollmann BC. Increased myofilament Ca2+-sensitivity and arrhythmia susceptibility. J Mol Cell Cardiol 2010; 48:824-33. [PMID: 20097204 PMCID: PMC2854218 DOI: 10.1016/j.yjmcc.2010.01.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 01/12/2010] [Accepted: 01/12/2010] [Indexed: 10/19/2022]
Abstract
Increased myofilament Ca(2+) sensitivity is a common attribute of many inherited and acquired cardiomyopathies that are associated with cardiac arrhythmias. Accumulating evidence supports the concept that increased myofilament Ca(2+) sensitivity is an independent risk factor for arrhythmias. This review describes and discusses potential underlying molecular and cellular mechanisms how myofilament Ca(2+) sensitivity affects cardiac excitation and leads to the generation of arrhythmias. Emphasized are downstream effects of increased myofilament Ca(2+) sensitivity: altered Ca(2+) buffering/handling, impaired energy metabolism and increased mechanical stretch, and how they may contribute to arrhythmogenesis.
Collapse
Affiliation(s)
- Sabine Huke
- Division of Clinical Pharmacology, Vanderbilt University, Nashville, TN 37232-0575, USA
| | | |
Collapse
|
39
|
Miura T, Miki T, Yano T. Role of the gap junction in ischemic preconditioning in the heart. Am J Physiol Heart Circ Physiol 2010; 298:H1115-25. [DOI: 10.1152/ajpheart.00879.2009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The gap junction plays roles not only in electrical coupling of cardiomyocytes but also in intercellular transport of biologically active substances. Furthermore, the gap junction participates in decision making on cell survival versus cell death in various types of cells, and a part of reperfusion injury in the heart has been indicated to be gap junction mediated. The contribution of gap junction communication (GJC) and/or mitochondrial “hemichannels” to protective signaling during the trigger phase of ischemic preconditioning (IPC) is suggested by observations that IPC failed to protect the heart when GJC was blocked during IPC. Although ischemia suppresses both electrical and chemical GJC, chemical GJC persists for a considerable time after electrical GJC is lost. IPC facilitates the ischemia-induced suppression of chemical GJC, whereas IPC delays the reduction of electrical GJC after ischemia. The inhibition of GJC during sustained ischemia and reperfusion by GJC blockers mimics the effect of IPC on myocardial necrosis. IPC induces distinct effects on the interaction of connexin-43 with protein kinases, and the phosphorylation of connexin-43 at Ser368 by PKCε is a primary mechanism of inhibition of chemical GJC by IPC. Several lines of evidence support the notion that the modulation of GJC is a part of the mechanism of IPC-induced protection against myocardial necrosis and arrhythmias, though what percentage of IPC protection is attributable to the inhibition of GJC during ischemia-reperfusion still remains unclear.
Collapse
Affiliation(s)
- Tetsuji Miura
- Division of Cardiology, Second Department of Internal Medicine, Sapporo Medical University, School of Medicine, Sapporo, Japan
| | - Takayuki Miki
- Division of Cardiology, Second Department of Internal Medicine, Sapporo Medical University, School of Medicine, Sapporo, Japan
| | - Toshiyuki Yano
- Division of Cardiology, Second Department of Internal Medicine, Sapporo Medical University, School of Medicine, Sapporo, Japan
| |
Collapse
|
40
|
Tramoni M, Gilleron J, Tahiri K, Carette D, Corvol MT, Segretain D, Pointis G, Savouret JF. Contraceptive steroids from pharmaceutical waste perturbate junctional communication in Sertoli cells. Biochimie 2009; 91:1366-75. [DOI: 10.1016/j.biochi.2009.09.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Accepted: 09/16/2009] [Indexed: 11/16/2022]
|
41
|
Sato M, Jiao Q, Honda T, Kurotani R, Toyota E, Okumura S, Takeya T, Minamisawa S, Lanier SM, Ishikawa Y. Activator of G protein signaling 8 (AGS8) is required for hypoxia-induced apoptosis of cardiomyocytes: role of G betagamma and connexin 43 (CX43). J Biol Chem 2009; 284:31431-40. [PMID: 19723622 DOI: 10.1074/jbc.m109.014068] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ischemic injury of the heart is associated with activation of multiple signal transduction systems including the heterotrimeric G-protein system. Here, we report a role of the ischemia-inducible regulator of G betagamma subunit, AGS8, in survival of cardiomyocytes under hypoxia. Cultured rat neonatal cardiomyocytes (NCM) were exposed to hypoxia or hypoxia/reoxygenation following transfection of AGS8siRNA or pcDNA::AGS8. Hypoxia-induced apoptosis of NCM was completely blocked by AGS8siRNA, whereas overexpression of AGS8 increased apoptosis. AGS8 formed complexes with G-proteins and channel protein connexin 43 (CX43), which regulates the permeability of small molecules under hypoxic stress. AGS8 initiated CX43 phosphorylation in a G betagamma-dependent manner by providing a scaffold composed of G betagamma and CX43. AGS8siRNA blocked internalization of CX43 following exposure of NCM to repetitive hypoxia; however it did not influence epidermal growth factor-mediated internalization of CX43. The decreased dye flux through CX43 that occurred with hypoxic stress was also prevented by AGS8siRNA. Interestingly, the G betagamma inhibitor Gallein mimicked the effect of AGS8 knockdown on both the CX43 internalization and the changes in cell permeability elicited by hypoxic stress. These data indicate that AGS8 is required for hypoxia-induced apoptosis of NCM, and that AGS8-G betagamma signal input increased the sensitivity of cells to hypoxic stress by influencing CX43 regulation and associated cell permeability. Under hypoxic stress, this unrecognized response program plays a critical role in the fate of NCM.
Collapse
Affiliation(s)
- Motohiko Sato
- Cardiovascular Research Institute, Yokohama City University School of Medicine, Fukuura, Yokohama 236-0004, Japan.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Easton JA, Petersen JS, Martin PEM. The anti-arrhythmic peptide AAP10 remodels Cx43 and Cx40 expression and function. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2009; 380:11-24. [PMID: 19326099 DOI: 10.1007/s00210-009-0411-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Accepted: 03/04/2009] [Indexed: 10/21/2022]
Abstract
The anti-arrhythmic peptide AAP10 has previously been shown to acutely upregulate electrical cell-to-cell coupling mediated via connexin 43 gap junctions. In the present work, we have further examined the connexin (Cx) specificity and mechanism of action of this peptide in HeLa cells expressing Cx43, Cx40 or Cx26. The ability of cells to transfer the small fluorescent dyes Alexa 488 (MW 570) or Alexa 594 (MW 759), as markers for metabolic coupling mediated via gap junctions, before and after exposure to AAP10 and/or the protein kinase C inhibitor chelerythrine for 5 h was determined by microinjection analysis. Immunofluorescence analysis assessed the effect of AAP10 on the spatial localisation of each Cx sub-type. Cell extracts were isolated for Western blot and reverse transcription polymerase chain reaction analysis at 0, 5, 10, 18 and 24 h following exposure to AAP10 and the relative Cx expression profiles determined. AAP10 enhanced the ability of Cx43 and, to a lesser extent, Cx40 to transfer Alexa 488. It also enhanced the ability of Cx43 to transfer Alexa 594 but not Cx40. Inhibition of protein kinase C blocked this enhanced response in both Cx sub-types. Western blot analysis determined that AAP10 induced Cx40 protein expression over periods of up to 24 h with an associated increase in the localisation of Cx40 at points of cell-to-cell contact following 24-h exposure. Cx43 expression was transiently induced following exposure to the peptide for 5-10 h, with an associated increase in Cx43 at points of cell-to-cell contact, returning to control levels by 18-24 h, via a post-translational mechanism independent of chelerythrine. A transient increase in Cx40 mRNA expression but not Cx43 mRNA expression was also observed. By contrast, AAP10 had no effect on the ability of Cx26 gap junctions to transfer the dyes or on the level of Cx26 expression. We propose that AAP10 is a versatile peptide that remodels metabolic coupling via Cx43 and to a lesser extent Cx40 gap junction channels via an initial protein-kinase-C-dependent pathway modifying local responses at the plasma membrane. This is followed by enhanced Cx43 or Cx40 protein expression.
Collapse
Affiliation(s)
- Jennifer A Easton
- Department of Biomedical and Biological Sciences, School of Life Sciences, Glasgow Caledonian University, Glasgow G4OBA, Scotland, UK
| | | | | |
Collapse
|
43
|
Abstract
Evidence is accumulating that some forms of cell death, like apoptosis, are not only governed by the complex interplay between extracellular and intracellular signals but are also strongly influenced by intercellular communicative networks. The latter is provided by arrays of channels consisting of connexin proteins, with gap junctions directly connecting the cytoplasm of neighboring cells and hemichannels positioned as pores that link the cytoplasm to the extracellular environment. The role of gap junctions in cell death communication has received considerable interest and recently hemichannels have joined in as potentially toxic pores adding their part to the cell death process. However, despite a large body of existing evidence, especially for gap junctions, the exact contribution of the connexin channel family still remains controversial, as both gap junctions and hemichannels may furnish cell death as well as cell survival signals. An additional layer of complexity is formed by the fact that connexin proteins as such, beyond their channel function, may influence the cell death process. We here review the current knowledge on connexins and their channels in cell death and specifically address the molecular mechanisms that underlie connexin-related signaling. We also briefly focus on pannexins, a novel set of connexin-like proteins that have been implicated in cellular responses to pathological insults.
Collapse
|
44
|
Clarke TC, Williams OJS, Martin PEM, Evans WH. ATP release by cardiac myocytes in a simulated ischaemia model: inhibition by a connexin mimetic and enhancement by an antiarrhythmic peptide. Eur J Pharmacol 2008; 605:9-14. [PMID: 19101539 DOI: 10.1016/j.ejphar.2008.12.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 11/18/2008] [Accepted: 12/01/2008] [Indexed: 02/06/2023]
Abstract
We studied the role of connexin hemichannels in the release of ATP by neonatal cardiac myocytes subject to ischaemic stress. Mechanical, osmotic and oxidative stress and changes in extracellular or intracellular Ca(2+) levels induce connexin hemichannels located in the plasma membrane to open and release small ions and molecules with signaling potential such as ATP. Since ATP release has been implicated in adaptation to oxygen deprivation, we studied its release by cardiac myocytes incubated in a custom-built hypoxia chamber for various periods. In a simulated ischaemia model (0.5% oxygen and 0.2 g/l glucose) a peak of ATP release occurred at 80 min followed by a return to steady state levels for a further 200 min. This peak of ATP release was not observed in myocytes subject to hypoxia (0.5% oxygen, 3.0 g/l glucose). ATP release in ischaemia was influenced by two classes of reagents that target connexins, the channel forming proteins of gap junctions. First, the connexin hemichannel inhibitors Gap 26 and 18a glycyrrhetinic acid abolished the ATP peak of release. Second, the AAP10, a peptide with antiarrhythmic properties markedly increased the peak of ATP release observed at 80 min of ischaemia and also induced a second smaller peak at 180-240 min. ATP content of the myocytes and Cx43 phosphorylation were monitored. Since the release of ATP in ischaemia was abolished by connexin channel inhibitors and stimulated by a peptide developed to target connexins in the context of cardiac arrhythmia, the results suggest that nucleotide release by connexin hemichannels is likely to feature in the response of myocytes to ischaemic stress in the heart.
Collapse
Affiliation(s)
- Thomas C Clarke
- Department of Medical Biochemistry and Immunology & Wales Heart Research Institute, Cardiff University, Cardiff, Wales, UK
| | | | | | | |
Collapse
|
45
|
Verma V, Hallett MB, Leybaert L, Martin PE, Evans WH. Perturbing plasma membrane hemichannels attenuates calcium signalling in cardiac cells and HeLa cells expressing connexins. Eur J Cell Biol 2008; 88:79-90. [PMID: 18951659 DOI: 10.1016/j.ejcb.2008.08.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 08/06/2008] [Accepted: 08/07/2008] [Indexed: 11/26/2022] Open
Abstract
Many cell signalling pathways are driven by changes in cytosolic calcium. We studied the effects of a range of inhibitors of connexin channels on calcium signalling in cardiac cells and HeLa cells expressing connexins. Gap 26 and 27, peptides that mimic short sequences in each of the extracellular loops of connexin 43, and anti-peptide antibodies generated to extracellular loop sequences of connexins, inhibited calcium oscillations in neonatal cardiac myocytes, as well as calcium transients induced by ATP in HL-1 cells originating from cardiac atrium and HeLa cells expressing connexin 43 or 26. Comparison of single with confluent cells showed that intracellular calcium responses were suppressed by interaction of connexin mimetic peptides and antibodies with hemichannels present on unapposed regions of the plasma membrane. To investigate how inhibition of hemichannels in the plasma membrane by the applied reagents was communicated to calcium store operation in the endoplasmic reticulum, we studied the effect of Gap 26 on calcium entry into cells and on intracellular IP3 release; both were inhibited by Gap 26. Calcium transients in both connexin 43- and connexin 26-expressing HeLa cells were inhibited by the peptides suggesting that the extended cytoplasmic carboxyl tail domain of larger connexins and their interactions with intracellular scaffolding/auxiliary proteins were unlikely to feature in transmitting peptide-induced perturbations at hemichannels in the plasma membrane to IP3 receptor channel central to calcium signalling. The results suggest that calcium levels in a microenvironment functionally connecting plasma membrane connexin hemichannels to downstream IP3-dependent calcium release channels in the endoplasmic reticulum were disrupted by the connexin mimetic peptide, although implication of other candidate hemichannels cannot be entirely discounted. Since calcium signalling is fundamental to the maintenance of cellular homeostasis, connexin hemichannels emerge as therapeutic targets open to manipulation by reagents interacting with external regions of these channels.
Collapse
Affiliation(s)
- Vandana Verma
- Department of Medical Biochemistry and Immunology, Cardiff University Medical School, Heath Park, Cardiff, Wales, UK
| | | | | | | | | |
Collapse
|
46
|
Jozwiak J, Dhein S. Local effects and mechanisms of antiarrhythmic peptide AAP10 in acute regional myocardial ischemia: electrophysiological and molecular findings. Naunyn Schmiedebergs Arch Pharmacol 2008; 378:459-70. [DOI: 10.1007/s00210-008-0317-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Accepted: 05/18/2008] [Indexed: 10/21/2022]
|
47
|
Kurebayashi N, Nishizawa H, Nakazato Y, Kurihara H, Matsushita S, Daida H, Ogawa Y. Aberrant cell-to-cell coupling in Ca2+-overloaded guinea pig ventricular muscles. Am J Physiol Cell Physiol 2008; 294:C1419-29. [DOI: 10.1152/ajpcell.00413.2007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate how intercellular coupling can be changed during Ca2+ overloading of ventricular muscle, we studied Ca2+ signals in individual cells and the histochemistry of the major gap junction channel, connexin43 (Cx43), using multicellular preparations. Papillary muscles were obtained from guinea pig ventricles and loaded with rhod-2. Sequential Ca2+ images of surface cells were obtained with a confocal microscope. In intact muscles, all cells showed simultaneous Ca2+ transients in response to field stimulation over a field of view of 0.3 × 0.3 mm2. In severely Ca2+-overloaded muscles, obtained by high-frequency stimulation in nonflowing Krebs solution, cells became less responsive to stimulation. Furthermore, nonsimultaneous but serial onsets of Ca2+ transients were often detected, suggesting a propagation delay of action potentials. The time lag of the onset between two aligned cells was sometimes as long as 100 ms. Similar lags were also observed in muscles with gap junction channels inhibited by heptanol. To investigate whether the phosphorylation state of Cx43 is affected in Ca2+-overloaded muscles, the distributions of phosphorylated and nonphosphorylated Cx43 were determined using specific antibodies. Most of the Cx43 was phosphorylated in the nonoverloaded muscles, whereas nonphosphorylated Cx43 was significantly elevated in severely Ca2+-overloaded muscles. Our results suggest that the propagation delay of action potential within a small area, a few square millimeters, can be a cause of abnormal conduction and a microreentry in Ca2+-overloaded heart. Inactivation of Na+ channels and inhibition of gap junctional communication may underlie the cell-to-cell propagation delay.
Collapse
|
48
|
Talhouk RS, Zeinieh MP, Mikati MA, El-Sabban ME. Gap junctional intercellular communication in hypoxia-ischemia-induced neuronal injury. Prog Neurobiol 2007; 84:57-76. [PMID: 18006137 DOI: 10.1016/j.pneurobio.2007.10.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 08/29/2007] [Accepted: 10/04/2007] [Indexed: 01/07/2023]
Abstract
Brain hypoxia-ischemia is a relatively common and serious problem in neonates and in adults. Its consequences include long-term histological and behavioral changes and reduction in seizure threshold. Gap junction intercellular communication is pivotal in the spread of hypoxia-ischemia related injury and in mediating its long-term effects. This review provides a comprehensive and critical review of hypoxia-ischemia and hypoxia in the brain and the potential role of gap junctions in the spread of the neuronal injury induced by these insults. It also presents the effects of hypoxia-ischemia and of hypoxia on the state of gap junctions in vitro and in vivo. Understanding the mechanisms involved in gap junction-mediated neuronal injury due to hypoxia will lead to the development of novel therapeutic strategies.
Collapse
Affiliation(s)
- Rabih S Talhouk
- Department of Biology, American University of Beirut, Beirut, Lebanon
| | | | | | | |
Collapse
|
49
|
Retamal MA, Schalper KA, Shoji KF, Orellana JA, Bennett MVL, Sáez JC. Possible involvement of different connexin43 domains in plasma membrane permeabilization induced by ischemia-reperfusion. J Membr Biol 2007; 218:49-63. [PMID: 17705051 DOI: 10.1007/s00232-007-9043-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2007] [Accepted: 06/15/2007] [Indexed: 01/04/2023]
Abstract
In vitro and in vivo studies support the involvement of connexin 43-based cell-cell channels and hemichannels in cell death propagation induced by ischemia-reperfusion. In this context, open connexin hemichannels in the plasma membrane have been proposed to act as accelerators of cell death. Progress on the mechanisms underlying the cell permeabilization induced by ischemia-reperfusion reveals the involvement of several factors leading to an augmented open probability and increased number of hemichannels on the cell surface. While open probability can be increased by a reduction in extracellular concentration of divalent cations and changes in covalent modifications of connexin 43 (oxidation and phosphorylation), increase in number of hemichannels requires an elevation of the intracellular free Ca(2+) concentration. Reversal of connexin 43 redox changes and membrane permeabilization can be induced by intracellular, but not extracellular, reducing agents, suggesting a cytoplasmic localization of the redox sensor(s). In agreement, hemichannels formed by connexin 45, which lacks cytoplasmic cysteines, or by connexin 43 with its C-terminal domain truncated to remove its cysteines are insensitive to reducing agents. Although further studies are required for a precise localization of the redox sensor of connexin 43 hemichannels, modulation of the redox potential is proposed as a target for the design of pharmacological tools to reduce cell death induced by ischemia-reperfusion in connexin 43-expressing cells.
Collapse
Affiliation(s)
- Mauricio A Retamal
- Departamento de Ciencias Fisiológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile
| | | | | | | | | | | |
Collapse
|
50
|
Zhang SW, Liu Y, Huang GZ, Liu L. Aconitine alters connexin43 phosphorylation status and [Ca2+] oscillation patterns in cultured ventricular myocytes of neonatal rats. Toxicol In Vitro 2007; 21:1476-85. [PMID: 17728094 DOI: 10.1016/j.tiv.2007.06.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 05/30/2007] [Accepted: 06/13/2007] [Indexed: 10/23/2022]
Abstract
Aconitine, a highly poisonous type of alkaloid, has a widespread effect in stimulating the membranes of cardiomyocyte. However, other effects of aconitine on cardiomyocyte are unknown. In this study, we investigated whether aconitine also affects the phosphorylation status of connexin43 (Cx43) and intracellular [Ca(2+)] oscillation patterns in cultured ventricular myocytes of neonatal rats. As determined by Western blot analysis, a decreased percentage (47.68+/-2.29%) of phosphorylated Cx43 (P-Cx43) and a concomitant increased percentage (52.32+/-2.29%) of nonphosphorylated Cx43 (NP-Cx43) were found in aconitine-treated cultures, compared to the controls (82.77+/-2.04% for P-Cx43 and 17.23+/-2.04% for NP-Cx43). Quantitative immunofluorescent microscopy revealed similar changes in phosphorylation status occurring in Cx43 containing gap junctions in the cultures under the same treatment conditions. Real-time laser scanning microscopy indicated that intracellular [Ca(2+)] oscillations were relatively stable in control cultures, with occasional calcium sparks; after being treated with aconitine, high frequency [Ca(2+)] oscillations emerged, whereas typical calcium sparks disappeared. Furthermore, Western blot analysis revealed that, after aconitine treatment, the amount of phosphorylated PKCalpha decreased significantly. These observations suggest that aconitine not only induces dephosphorylation of Cx43 and PKCalpha, but also alters intracellular [Ca(2+)] oscillation patterns in cultured cardiomyocytes.
Collapse
Affiliation(s)
- Shi-Wei Zhang
- Department of Forensic Medicine, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | | | | | | |
Collapse
|