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Papadakos SP, Chatzikalil E, Arvanitakis K, Vakadaris G, Stergiou IE, Koutsompina ML, Argyrou A, Lekakis V, Konstantinidis I, Germanidis G, Theocharis S. Understanding the Role of Connexins in Hepatocellular Carcinoma: Molecular and Prognostic Implications. Cancers (Basel) 2024; 16:1533. [PMID: 38672615 PMCID: PMC11048329 DOI: 10.3390/cancers16081533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 04/28/2024] Open
Abstract
Connexins, a family of tetraspan membrane proteins forming intercellular channels localized in gap junctions, play a pivotal role at the different stages of tumor progression presenting both pro- and anti-tumorigenic effects. Considering the potential role of connexins as tumor suppressors through multiple channel-independent mechanisms, their loss of expression may be associated with tumorigenic activity, while it is hypothesized that connexins favor the clonal expansion of tumor cells and promote cell migration, invasion, and proliferation, affecting metastasis and chemoresistance in some cases. Hepatocellular carcinoma (HCC), characterized by unfavorable prognosis and limited responsiveness to current therapeutic strategies, has been linked to gap junction proteins as tumorigenic factors with prognostic value. Notably, several members of connexins have emerged as promising markers for assessing the progression and aggressiveness of HCC, as well as the chemosensitivity and radiosensitivity of hepatocellular tumor cells. Our review sheds light on the multifaceted role of connexins in HCC pathogenesis, offering valuable insights on recent advances in determining their prognostic and therapeutic potential.
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Affiliation(s)
- Stavros P. Papadakos
- First Department of Pathology, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (S.P.P.); (E.C.)
| | - Elena Chatzikalil
- First Department of Pathology, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (S.P.P.); (E.C.)
| | - Konstantinos Arvanitakis
- Division of Gastroenterology and Hepatology, First Department of Internal Medicine, AHEPA University Hospital, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (K.A.); (G.V.)
- Basic and Translational Research Unit, Special Unit for Biomedical Research and Education, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece
| | - Georgios Vakadaris
- Division of Gastroenterology and Hepatology, First Department of Internal Medicine, AHEPA University Hospital, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (K.A.); (G.V.)
| | - Ioanna E. Stergiou
- Pathophysiology Department, School of Medicine, National and Kapodistrian University of Athens, 11527 Athens, Greece; (I.E.S.); (M.-L.K.)
| | - Maria-Loukia Koutsompina
- Pathophysiology Department, School of Medicine, National and Kapodistrian University of Athens, 11527 Athens, Greece; (I.E.S.); (M.-L.K.)
| | - Alexandra Argyrou
- Academic Department of Gastroenterology, Laikon General Hospital, Athens University Medical School, 11527 Athens, Greece; (A.A.); (V.L.)
| | - Vasileios Lekakis
- Academic Department of Gastroenterology, Laikon General Hospital, Athens University Medical School, 11527 Athens, Greece; (A.A.); (V.L.)
| | | | - Georgios Germanidis
- Division of Gastroenterology and Hepatology, First Department of Internal Medicine, AHEPA University Hospital, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece; (K.A.); (G.V.)
- Basic and Translational Research Unit, Special Unit for Biomedical Research and Education, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece
| | - Stamatios Theocharis
- First Department of Pathology, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (S.P.P.); (E.C.)
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2
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Martins-Marques T, Witschas K, Ribeiro I, Zuzarte M, Catarino S, Ribeiro-Rodrigues T, Caramelo F, Aasen T, Carreira IM, Goncalves L, Leybaert L, Girao H. Cx43 can form functional channels at the nuclear envelope and modulate gene expression in cardiac cells. Open Biol 2023; 13:230258. [PMID: 37907090 PMCID: PMC10645070 DOI: 10.1098/rsob.230258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 09/12/2023] [Indexed: 11/02/2023] Open
Abstract
Classically associated with gap junction-mediated intercellular communication, connexin43 (Cx43) is increasingly recognized to possess non-canonical biological functions, including gene expression regulation. However, the mechanisms governing the localization and role played by Cx43 in the nucleus, namely in transcription modulation, remain unknown. Using comprehensive and complementary approaches encompassing biochemical assays, super-resolution and immunogold transmission electron microscopy, we demonstrate that Cx43 localizes to the nuclear envelope of different cell types and in cardiac tissue. We show that translocation of Cx43 to the nucleus relies on Importin-β, and that Cx43 significantly impacts the cellular transcriptome, likely by interacting with transcriptional regulators. In vitro patch-clamp recordings from HEK293 and adult primary cardiomyocytes demonstrate that Cx43 forms active channels at the nuclear envelope, providing evidence that Cx43 can participate in nucleocytoplasmic shuttling of small molecules. The accumulation of nuclear Cx43 during myogenic differentiation of cardiomyoblasts is suggested to modulate expression of genes implicated in this process. Altogether, our study provides new evidence for further defining the biological roles of nuclear Cx43, namely in cardiac pathophysiology.
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Affiliation(s)
- Tania Martins-Marques
- Univ Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3004-504 Coimbra, Portugal
- Clinical Academic Centre of Coimbra (CACC), 3004-561 Coimbra, Portugal
| | - Katja Witschas
- Department of Basic Medical Sciences – Physiology group, Ghent University, 9000 Ghent, Belgium
| | - Ilda Ribeiro
- Univ Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3004-504 Coimbra, Portugal
- Univ Coimbra, Cytogenetics and Genomics Laboratory (CIMAGO), Faculty of Medicine, 3004-531 Coimbra, Portugal
| | - Mónica Zuzarte
- Univ Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3004-504 Coimbra, Portugal
- Clinical Academic Centre of Coimbra (CACC), 3004-561 Coimbra, Portugal
| | - Steve Catarino
- Univ Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3004-504 Coimbra, Portugal
- Clinical Academic Centre of Coimbra (CACC), 3004-561 Coimbra, Portugal
| | - Teresa Ribeiro-Rodrigues
- Univ Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3004-504 Coimbra, Portugal
- Clinical Academic Centre of Coimbra (CACC), 3004-561 Coimbra, Portugal
| | - Francisco Caramelo
- Univ Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3004-504 Coimbra, Portugal
- Univ Coimbra, Laboratory of Biostatistics and Medical Informatics, Faculty of Medicine, 3004-531 Coimbra, Portugal
| | - Trond Aasen
- Patologia Molecular Translacional, Vall d'Hebron Institut de Recerca (VHIR), Vall d'Hebron Hospital Universitari, Vall d'Hebron Barcelona Hospital Campus, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain
- CIBER de Cáncer (CIBERONC), Instituto de Salud Carlos III, Avenida de Monforte de Lemos 3-5, 28029 Madrid, Spain
| | - Isabel Marques Carreira
- Univ Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3004-504 Coimbra, Portugal
- Univ Coimbra, Cytogenetics and Genomics Laboratory (CIMAGO), Faculty of Medicine, 3004-531 Coimbra, Portugal
| | - Lino Goncalves
- Univ Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3004-504 Coimbra, Portugal
- Clinical Academic Centre of Coimbra (CACC), 3004-561 Coimbra, Portugal
| | - Luc Leybaert
- Department of Basic Medical Sciences – Physiology group, Ghent University, 9000 Ghent, Belgium
| | - Henrique Girao
- Univ Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3004-504 Coimbra, Portugal
- Clinical Academic Centre of Coimbra (CACC), 3004-561 Coimbra, Portugal
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3
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Ek-Vitorin JF, Jiang JX. The Role of Gap Junctions Dysfunction in the Development of Cataracts: From Loss of Cell-to-Cell Transfer to Blurred Vision-Review. Bioelectricity 2023; 5:164-172. [PMID: 37746311 PMCID: PMC10516237 DOI: 10.1089/bioe.2023.0025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/26/2023] Open
Abstract
Mutations of lens connexins are linked to congenital cataracts. However, the role of connexin mutations in the development of age-related lens opacification remains largely unknown. Here, we present a focused review of the literature on lens organization and factors associated with cataract development. Several lines of evidence indicate that disturbances of the lens circulation by dysfunctional connexin channels, and/or accumulation of protein damage due to oxidative stress, are key factors in cataract development. Phosphorylation by protein kinase A improves the permeability of connexins channels to small molecules and mitigates the lens clouding induced by oxidative stress. We conclude (1) that connexin channels are central to the lens circulation and (2) that their permeability to antioxidant molecules contributes to the maintenance of lens transparency.
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Affiliation(s)
| | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, Texas, USA
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4
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Gallego C, Jaracz-Ros A, Laganà M, Mercier-Nomé F, Domenichini S, Fumagalli A, Roingeard P, Herfs M, Pidoux G, Bachelerie F, Schlecht-Louf G. Reprogramming of connexin landscape fosters fast gap junction intercellular communication in human papillomavirus-infected epithelia. Front Cell Infect Microbiol 2023; 13:1138232. [PMID: 37260709 PMCID: PMC10228504 DOI: 10.3389/fcimb.2023.1138232] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 04/26/2023] [Indexed: 06/02/2023] Open
Abstract
Human papillomaviruses (HPVs) are highly prevalent commensal viruses that require epithelial stratification to complete their replicative cycle. While HPV infections are most often asymptomatic, certain HPV types can cause lesions, that are usually benign. In rare cases, these infections may progress to non-replicative viral cycles associated with high HPV oncogene expression promoting cell transformation, and eventually cancer when not cleared by host responses. While the consequences of HPV-induced transformation on keratinocytes have been extensively explored, the impact of viral replication on epithelial homeostasis remains largely unexplored. Gap junction intercellular communication (GJIC) is critical for stratified epithelium integrity and function. This process is ensured by a family of proteins named connexins (Cxs), including 8 isoforms that are expressed in stratified squamous epithelia. GJIC was reported to be impaired in HPV-transformed cells, which was attributed to the decreased expression of the Cx43 isoform. However, it remains unknown whether and how HPV replication might impact on the expression of Cx isoforms and GJIC in stratified squamous epithelia. To address this question, we have used 3D-epithelial cell cultures (3D-EpCs), the only model supporting the productive HPV life cycle. We report a transcriptional downregulation of most epithelial Cx isoforms except Cx45 in HPV-replicating epithelia. At the protein level, HPV replication results in a reduction of Cx43 expression while that of Cx45 increases and displays a topological shift toward the cell membrane. To quantify GJIC, we pioneered quantitative gap-fluorescence loss in photobleaching (FLIP) assay in 3D-EpCs, which allowed us to show that the reprogramming of Cx landscape in response to HPV replication translates into accelerated GJIC in living epithelia. Supporting the pathophysiological relevance of our observations, the HPV-associated Cx43 and Cx45 expression pattern was confirmed in human cervical biopsies harboring HPV. In conclusion, the reprogramming of Cx expression and distribution in HPV-replicating epithelia fosters accelerated GJIC, which may participate in epithelial homeostasis and host immunosurveillance.
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Affiliation(s)
- Carmen Gallego
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
| | - Agnieszka Jaracz-Ros
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
| | - Marta Laganà
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
| | - Françoise Mercier-Nomé
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
- US31-UMS3679-Plateforme PHIC, Ingénierie et Plateformes au Service de l’Innovation Thérapeutique (IPSIT), INSERM, CNRS, Université Paris-Saclay, Orsay, France
| | - Séverine Domenichini
- UMS-IPSIT Plateforme MIPSIT, Université Paris-Saclay, CNRS, Inserm, Ingénierie et Plateformes au Service de l’Innovation Thérapeutique, Orsay, France
| | - Amos Fumagalli
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France
| | - Philippe Roingeard
- INSERM U1259, Université de Tours et CHRU de Tours & Plateforme IBiSA des Microscopies, PPF ASB, CHRU de Tours, Tours, France
| | - Michael Herfs
- Laboratory of Experimental Pathology, GIGA-Cancer, University of Liège, Liège, Belgium
| | | | - Françoise Bachelerie
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
| | - Géraldine Schlecht-Louf
- Inflammation, Microbiome and Immunosurveillance, INSERM UMR-996, Université Paris-Saclay, Orsay, France
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5
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Basu I, Li H, Trease AJ, Sorgen PL. Regulation of Cx43 Gap Junction Intercellular Communication by Bruton's Tyrosine Kinase and Interleukin-2-Inducible T-Cell Kinase. Biomolecules 2023; 13:biom13040660. [PMID: 37189407 DOI: 10.3390/biom13040660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/30/2023] [Accepted: 04/06/2023] [Indexed: 05/17/2023] Open
Abstract
T and B cell receptor signaling involves the activation of Akt, MAPKs, and PKC as well as an increase in intracellular Ca2+ and calmodulin activation. While these coordinate the rapid turnover of gap junctions, also implicated in this process is Src, which is not activated as part of T and B cell receptor signaling. An in vitro kinase screen identified that Bruton's tyrosine kinase (BTK) and interleukin-2-inducible T-cell kinase (ITK) phosphorylate Cx43. Mass spectroscopy revealed that BTK and ITK phosphorylate Cx43 residues Y247, Y265, and Y313, which are identical to the residues phosphorylated by Src. Overexpression of BTK or ITK in the HEK-293T cells led to increased Cx43 tyrosine phosphorylation as well as decreased gap junction intercellular communication (GJIC) and Cx43 membrane localization. In the lymphocytes, activation of the B cell receptor (Daudi cells) or T cell receptor (Jurkat cells) increased the BTK and ITK activity, respectively. While this led to increased tyrosine phosphorylation of Cx43 and decreased GJIC, the cellular localization of Cx43 changed little. We have previously identified that Pyk2 and Tyk2 also phosphorylate Cx43 at residues Y247, Y265, and Y313 with a similar cellular fate to that of Src. With phosphorylation critical to Cx43 assembly and turnover, and kinase expression varying between different cell types, there would be a need for different kinases to achieve the same regulation of Cx43. The work presented herein suggests that in the immune system, ITK and BTK have the capacity for the tyrosine phosphorylation of Cx43 to alter the gap junction function in a similar manner as Pyk2, Tyk2, and Src.
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Affiliation(s)
- Ishika Basu
- 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
| | - Andrew J Trease
- Department of Biochemistry and Molecular Biology, 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
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6
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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: 0] [Impact Index Per Article: 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.
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Zhou M, Zheng M, Zhou X, Tian S, Yang X, Ning Y, Li Y, Zhang S. The roles of connexins and gap junctions in the progression of cancer. Cell Commun Signal 2023; 21:8. [PMID: 36639804 PMCID: PMC9837928 DOI: 10.1186/s12964-022-01009-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 12/03/2022] [Indexed: 01/15/2023] Open
Abstract
Gap junctions (GJs), which are composed of connexins (Cxs), provide channels for direct information exchange between cells. Cx expression has a strong spatial specificity; however, its influence on cell behavior and information exchange between cells cannot be ignored. A variety of factors in organisms can modulate Cxs and subsequently trigger a series of responses that have important effects on cellular behavior. The expression and function of Cxs and the number and function of GJs are in dynamic change. Cxs have been characterized as tumor suppressors in the past, but recent studies have highlighted the critical roles of Cxs and GJs in cancer pathogenesis. The complex mechanism underlying Cx and GJ involvement in cancer development is a major obstacle to the evolution of therapy targeting Cxs. In this paper, we review the post-translational modifications of Cxs, the interactions of Cxs with several chaperone proteins, and the effects of Cxs and GJs on cancer. Video Abstract.
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Affiliation(s)
- Mingming Zhou
- grid.265021.20000 0000 9792 1228Graduate School, Tianjin Medical University, Tianjin, 300070 People’s Republic of China
| | - Minying Zheng
- Department of Pathology, Tianjin Union Medical Center, Nankai University, Tianjin, 300121 People’s Republic of China
| | - Xinyue Zhou
- grid.265021.20000 0000 9792 1228Graduate School, Tianjin Medical University, Tianjin, 300070 People’s Republic of China
| | - Shifeng Tian
- grid.265021.20000 0000 9792 1228Graduate School, Tianjin Medical University, Tianjin, 300070 People’s Republic of China
| | - Xiaohui Yang
- grid.216938.70000 0000 9878 7032Nankai University School of Medicine, Nankai University, Tianjin, 300071 People’s Republic of China
| | - Yidi Ning
- grid.216938.70000 0000 9878 7032Nankai University School of Medicine, Nankai University, Tianjin, 300071 People’s Republic of China
| | - Yuwei Li
- grid.417031.00000 0004 1799 2675Department of Colorectal Surgery, Tianjin Union Medical Center, Tianjin, 300121 People’s Republic of China
| | - Shiwu Zhang
- Department of Pathology, Tianjin Union Medical Center, Nankai University, Tianjin, 300121 People’s Republic of China
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Pun R, Kim MH, North BJ. Role of Connexin 43 phosphorylation on Serine-368 by PKC in cardiac function and disease. Front Cardiovasc Med 2023; 9:1080131. [PMID: 36712244 PMCID: PMC9877470 DOI: 10.3389/fcvm.2022.1080131] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 12/19/2022] [Indexed: 01/13/2023] Open
Abstract
Intercellular communication mediated by gap junction channels and hemichannels composed of Connexin 43 (Cx43) is vital for the propagation of electrical impulses through cardiomyocytes. The carboxyl terminal tail of Cx43 undergoes various post-translational modifications including phosphorylation of its Serine-368 (S368) residue. Protein Kinase C isozymes directly phosphorylate S368 to alter Cx43 function and stability through inducing conformational changes affecting channel permeability or promoting internalization and degradation to reduce intercellular communication between cardiomyocytes. Recent studies have implicated this PKC/Cx43-pS368 circuit in several cardiac-associated diseases. In this review, we describe the molecular and cellular basis of PKC-mediated Cx43 phosphorylation and discuss the implications of Cx43 S368 phosphorylation in the context of various cardiac diseases, such as cardiomyopathy, as well as the therapeutic potential of targeting this pathway.
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Affiliation(s)
- Renju Pun
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, United States
| | - Michael H. Kim
- CHI Health Heart Institute, School of Medicine, Creighton University, Omaha, NE, United States
| | - Brian J. North
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, United States,*Correspondence: Brian J. North,
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9
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Xu WT, Shi LL, Xu J, Qian H, Zhou H, Wang LH. Ezrin expression in female reproductive tissues: A review of regulation and pathophysiological implications. Front Cell Dev Biol 2023; 11:1125881. [PMID: 36968198 PMCID: PMC10030596 DOI: 10.3389/fcell.2023.1125881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 02/27/2023] [Indexed: 03/29/2023] Open
Abstract
Ezrin, a plasma membrane-microfilament linker, is a cytoskeletal organizer involved in many cellular activities by binding to the membrane protein-ezrin-cytoskeletal protein complex and regulating downstream signal transduction. Increasing evidence demonstrates that ezrin plays an important role in regulating cell polarity, proliferation and invasion. In this study, we analyzed the effects of ezrin on oocytes, follicle development, embryo development and embryo implantation. We reviewed the recent studies on the modalities of ezrin regulation and its involvement in the biological processes of female reproductive physiology and summarized the current research advances in ezrin inhibitors. These studies will provide new strategies and insights for the treatment of diseases.
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Affiliation(s)
- Wen-Ting Xu
- Department of Reproduction, Zhangjiagang TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Zhangjiagang, Suzhou, Jiangsu, China
| | - Ling-Li Shi
- Department of Reproduction, Zhangjiagang TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Zhangjiagang, Suzhou, Jiangsu, China
| | - Jie Xu
- Translational Medical Innovation Center, Zhangjiagang TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Zhangjiagang, Suzhou, Jiangsu, China
| | - Haiqing Qian
- Department of Reproduction, Zhangjiagang TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Zhangjiagang, Suzhou, Jiangsu, China
| | - Huifang Zhou
- Department of Gynaecology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
- *Correspondence: Huifang Zhou, ; Li-Hong Wang,
| | - Li-Hong Wang
- Department of Reproduction, Zhangjiagang TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Zhangjiagang, Suzhou, Jiangsu, China
- *Correspondence: Huifang Zhou, ; Li-Hong Wang,
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10
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Zhao Y, Pasanen M, Rysä J. Placental ion channels: potential target of chemical exposure. Biol Reprod 2022; 108:41-51. [PMID: 36173899 PMCID: PMC9843680 DOI: 10.1093/biolre/ioac186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 09/23/2022] [Accepted: 09/29/2022] [Indexed: 01/21/2023] Open
Abstract
The placenta is an important organ for the exchange of substances between the fetus and the mother, hormone secretion, and fetoplacental immunological defense. Placenta has an organ-specific distribution of ion channels and trophoblasts, and placental vessels express a large number of ion channels. Several placental housekeeping activities and pregnancy complications are at least partly controlled by ion channels, which are playing an important role in regulating hormone secretion, trophoblastic homeostasis, ion transport, and vasomotor activity. The function of several placental ion channels (Na, Ca, and Cl ion channels, cation channel, nicotinic acetylcholine receptors, and aquaporin-1) is known to be influenced by chemical exposure, i.e., their responses to different chemicals have been tested and confirmed in experimental models. Here, we review the possibility that placental ion channels are targets of toxicological concern in terms of placental function, fetal growth, and development.
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Affiliation(s)
- Yi Zhao
- Department of Obstetrics, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning, China
| | - Markku Pasanen
- School of Pharmacy, University of Eastern Finland, Kuopio, Finland
| | - Jaana Rysä
- Correspondence: School of Pharmacy, University of Eastern Finland, POB 1627, Kuopio 70211, Finland. Tel: +358403552412; E-mail:
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11
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Guo W, Gao H, Pan W, Yu P, Che G. High glucose induces Nox4 expression and podocyte apoptosis through the Smad3/ezrin/PKA pathway. Biol Open 2021; 10:bio.055012. [PMID: 33046439 PMCID: PMC8181897 DOI: 10.1242/bio.055012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 09/28/2020] [Indexed: 12/27/2022] Open
Abstract
Podocytes are the major target in proteinuric kidney diseases such as diabetic nephropathy. The underlying molecular mechanisms by which high glucose (HG) results in podocyte damage remain unclear. This study investigated the regulatory role of Smad3, ezrin, and protein kinase A (PKA) in NADPH oxidase (Nox4) expression, reactive oxidative species (ROS) production, and apoptosis in HG-treated podocytes. A human podocyte cell line was cultured and differentiated, then treated with 30 mM HG. Apoptosis and intracellular ROS levels were assessed using TUNEL and DCF assays, respectively. Expressions of Nox4, phospho-Smad3Ser423/425, phospho-PKAThr197, and phospho-ezrinThr567 were evaluated using western blotting. ELISA was used to quantify intracellular cAMP concentration and PKA activity. Knockdown assay was used to inhibit the expressions of Smad3, Nox4, and ezrin by lentiviral shRNA. In HG-treated podocytes, the level of phospho-Smad3Ser423/425 and phospho-ezrinThr567 was increased significantly, which was accompanied by the reduction of cAMP and phospho-PKAThr197. HG-induced apoptosis was significantly prevented by the Smad3-inhibitor SIS3 or shRNA-Smad3. In podocytes expressing shRNA-ezrin or shRNA-Nox4, apoptosis was remarkably mitigated following HG treatment. HG-induced upregulation of phospho-ezrinThr567 and downregulation of phospho-PKAThr197 was significantly prevented by SIS3, shRNA-ezrin or shRNA-Smad3. Forskolin, a PKA activator, significantly inhibited HG-mediated upregulation of Nox4 expression, ROS generation, and apoptosis. Additionally, an increase in the ROS level was prohibited in HG-treated podocytes with the knockdown of Nox4, Smad3, or ezrin. Taken together, our findings provided evidence that Smad3-mediated ezrin activation upregulates Nox4 expression and ROS production, by suppressing PKA activity, which may at least in part contribute to HG-induced podocyte apoptosis. Summary: The actin-membrane linker protein ezrin-related signaling plays a critical role in podocyte apoptosis through regulation of Nox4 expression and ROS production.
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Affiliation(s)
- Wanxu Guo
- Department of Pediatrics, Second Hospital, Jilin University, Changchun, 130041, China
| | - Hang Gao
- The Key Laboratory of Pathobiology, Ministry of Education, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China
| | - Wei Pan
- Department of Pediatrics, Second Hospital, Jilin University, Changchun, 130041, China
| | - Panapn Yu
- Department of Pediatrics, Second Hospital, Jilin University, Changchun, 130041, China
| | - Guanghua Che
- Department of Pediatrics, Second Hospital, Jilin University, Changchun, 130041, China
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Lone AM, Taskén K. Phosphoproteomics-Based Characterization of Prostaglandin E 2 Signaling in T Cells. Mol Pharmacol 2021; 99:370-382. [PMID: 33674363 DOI: 10.1124/molpharm.120.000170] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 03/01/2021] [Indexed: 12/24/2022] Open
Abstract
Prostaglandin E2 (PGE2) is a key lipid mediator in health and disease and serves as a crucial link between the immune response and cancer. With the advent of cancer therapies targeting PGE2 signaling pathways at different levels, there has been increased interest in mapping and understanding the complex and interconnected signaling pathways arising from the four distinct PGE2 receptors. Here, we review phosphoproteomics studies that have investigated different aspects of PGE2 signaling in T cells. These studies have elucidated PGE2's regulatory effect on T cell receptor signaling and T cell function, the key role of protein kinase A in many PGE2 signaling pathways, the temporal regulation of PGE2 signaling, differences in PGE2 signaling between different T cell subtypes, and finally, the crosstalk between PGE2 signaling pathways elicited by the four distinct PGE2 receptors present in T cells. SIGNIFICANCE STATEMENT: Through the reviewed studies, we now have a much better understanding of PGE2's signaling mechanisms and functional roles in T cells, as well as a solid platform for targeted and functional studies of specific PGE2-triggered pathways in T cells.
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Affiliation(s)
- Anna Mari Lone
- Department of Cancer Immunology, Institute for Cancer Research, Oslo University Hospital (A.M.L., K.T.) and Institute for Clinical Medicine, University of Oslo, Oslo, Norway (K.T.)
| | - Kjetil Taskén
- Department of Cancer Immunology, Institute for Cancer Research, Oslo University Hospital (A.M.L., K.T.) and Institute for Clinical Medicine, University of Oslo, Oslo, Norway (K.T.)
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Connexins and cAMP Cross-Talk in Cancer Progression and Metastasis. Cancers (Basel) 2020; 13:cancers13010058. [PMID: 33379194 PMCID: PMC7795795 DOI: 10.3390/cancers13010058] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/21/2020] [Accepted: 12/21/2020] [Indexed: 02/06/2023] Open
Abstract
Simple Summary Different connexins play diverse roles in cancers, either tumor-suppressing or tumor-promoting. In lung cancer, Cx43 serves as a tumor suppressor at the early stage, but it can also be a tumor-promotor at an advanced stage and during metastasis. Moreover, other connexins, including Cx26, Cx31.1, and Cx32, can be tumor suppressors. In contrast, Cx30.3 can be a tumor-promotor. The roles of different connexins in different cancers have also been established. Cx43 acts as a tumor suppressor in colorectal cancer, breast cancer, and glioma, whereas Cx32 can be a suppressor in liver tumors and hepatocarcinogenesis. Cx26 can be a tumor suppressor in mammary tumors; in contrast, it can be a tumor-promotor in melanoma. Existing drugs/molecules targeting the cAMP/PKA/connexin axis act to regulate channel opening/closing. Mimic peptides, such as Gap19, Gap26, and Gap 27 block hemichannels, mimetic peptides, and CT9/CT10 and promote hemichannel opening and also hemichannel closing. Abstract Connexin-containing gap junctions mediate the direct exchange of small molecules between cells, thus promoting cell–cell communication. Connexins (Cxs) have been widely studied as key tumor-suppressors. However, certain Cx subtypes, such as Cx43 and Cx26, are overexpressed in metastatic tumor lesions. Cyclic adenosine monophosphate (cAMP) signaling regulates Cx expression and function via transcriptional control and phosphorylation. cAMP also passes through gap junction channels between adjacent cells, regulating cell cycle progression, particularly in cancer cell populations. Low levels of cAMP are sufficient to activate key effectors. The present review evaluates the mechanisms underlying Cx regulation by cAMP signaling and the role of gap junctions in cancer progression and metastasis. A deeper understanding of these processes might facilitate the development of novel anticancer drugs.
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Adu-Gyamfi EA, Czika A, Gorleku PN, Ullah A, Panhwar Z, Ruan LL, Ding YB, Wang YX. The Involvement of Cell Adhesion Molecules, Tight Junctions, and Gap Junctions in Human Placentation. Reprod Sci 2020; 28:305-320. [PMID: 33146876 DOI: 10.1007/s43032-020-00364-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/19/2020] [Indexed: 02/06/2023]
Abstract
Placentation is a major determinant of the success of pregnancy. It is regulated by several factors such as cell adhesion molecules, tight junctions, and gap junctions. The cell adhesion molecules are integrins, cadherins, immunoglobulins, nectins, and selectins. The tight junctions are composed of claudins, occludin, and junction adhesion molecule proteins while the gap junctions are composed of connexins of varying molecular weights. During placentation, some of these molecules regulate trophoblast proliferation, trophoblast fusion, trophoblast migration, trophoblast invasion, trophoblast-endothelium adhesion, glandular remodeling, and spiral artery remodeling. There is a dysregulated placental expression of some of these molecules during obstetric complications. We have, hereby, indicated the expression patterns of the subunits of each of these molecules in the various trophoblast subtypes and in the decidua, and have highlighted their involvement in physiological and pathological placentation. The available evidence points to the relevance of these molecules as distinguishing markers of the various trophoblast lineages and as potential therapeutic targets in the management of malplacentation-mediated diseases.
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Affiliation(s)
- Enoch Appiah Adu-Gyamfi
- Department of Reproductive Sciences, School of Basic Medicine, Chongqing Medical University, Chongqing, 400016, People's Republic of China.
- Joint International Research Laboratory of Reproduction & Development, Chongqing Medical University, Box 197, No. 1 Yixueyuan Rd, Chongqing, 400016, People's Republic of China.
| | - Armin Czika
- Joint International Research Laboratory of Reproduction & Development, Chongqing Medical University, Box 197, No. 1 Yixueyuan Rd, Chongqing, 400016, People's Republic of China
| | - Philip Narteh Gorleku
- Department of Medical Imaging, School of Medical Sciences, University of Cape Coast, Cape Coast, Republic of Ghana
| | - Amin Ullah
- Joint International Research Laboratory of Reproduction & Development, Chongqing Medical University, Box 197, No. 1 Yixueyuan Rd, Chongqing, 400016, People's Republic of China
| | - Zulqarnain Panhwar
- Joint International Research Laboratory of Reproduction & Development, Chongqing Medical University, Box 197, No. 1 Yixueyuan Rd, Chongqing, 400016, People's Republic of China
| | - Ling-Ling Ruan
- Joint International Research Laboratory of Reproduction & Development, Chongqing Medical University, Box 197, No. 1 Yixueyuan Rd, Chongqing, 400016, People's Republic of China
| | - Yu-Bin Ding
- Department of Reproductive Sciences, School of Basic Medicine, Chongqing Medical University, Chongqing, 400016, People's Republic of China.
- Joint International Research Laboratory of Reproduction & Development, Chongqing Medical University, Box 197, No. 1 Yixueyuan Rd, Chongqing, 400016, People's Republic of China.
| | - Ying-Xiong Wang
- Department of Reproductive Sciences, School of Basic Medicine, Chongqing Medical University, Chongqing, 400016, People's Republic of China.
- Joint International Research Laboratory of Reproduction & Development, Chongqing Medical University, Box 197, No. 1 Yixueyuan Rd, Chongqing, 400016, People's Republic of China.
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Ezrin interacts with L-periaxin by the "head to head and tail to tail" mode and influences the location of L-periaxin in Schwann cell RSC96. Biochim Biophys Acta Gen Subj 2020; 1864:129520. [PMID: 31931020 DOI: 10.1016/j.bbagen.2020.129520] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 12/31/2019] [Accepted: 01/09/2020] [Indexed: 01/01/2023]
Abstract
In the peripheral nervous system (PNS), Schwann cells (SCs) are required for the myelination of axons. Periaxin (PRX), one of the myelination proteins expressed in SCs, is critical for the normal development and maintenance of PNS. As a member of the ERM (ezrin-radxin-moesin) protein family, ezrin holds our attention since their link to the formation of the nodes of Ranvier. Furthermore, PRX and ezrin are co-expressed in cytoskeletal complexes with periplakin and desmoyokin in lens fiber cells. In the present study, we observed that L-periaxin and ezrin interacted in a "head to head and tail to tail" mode in SC RSC96 through NLS3 region of L-periaxin with F3 subdomain of ezrin interaction, and the region of L-periaxin (residues 1368-1461) with ezrin (residues 475-557) interaction. A phosphorylation-mimicking mutation of ezrin resulted in L-periaxin accumulation on SC RSC96 membrane. Ezrin could inhibit the self-association of L-periaxin, and ezrin overexpression in sciatic nerve injury rats could facilitate the repair of impaired myelin sheath. Therefore, the interaction between L-periaxin and ezrin may adopt a close form to complete protein accumulation and to participate in myelin sheath maintenance.
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Xie J, Wang X, Ge H, Peng F, Zheng N, Wang Q, Tao L. Cx32 mediates norepinephrine-promoted EGFR-TKI resistance in a gap junction-independent manner in non-small-cell lung cancer. J Cell Physiol 2019; 234:23146-23159. [PMID: 31152452 DOI: 10.1002/jcp.28881] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 05/07/2019] [Accepted: 05/09/2019] [Indexed: 01/10/2023]
Abstract
The second-generation EGFR-TKI Afatinib is an irreversible ErbB family blocker used to treat patients with non-small-cell lung cancer (NSCLC). Unfortunately, resistance to this drug develops over time, and patients are always under great psychological pressure. A previous study showed that chronic stress hormones participate in EGFR-TKI resistance via β2 -AR signaling via an IL-6 dependent mechanism. Our study further explores a novel potential underlying mechanism. In the present study, we show that the stress hormone norepinephrine (NE) promotes Afatinib resistance by upregulating Cx32 expression. Furthermore, we, for the first time, find that Cx32 is a target gene for transcription factor CREB and NE enhances Cx32 mRNA expression by activation of CREB. We also demonstrate that Cx32 promotes Afatinib resistance by decreasing the degradation of EGFR-TKI resistance-associated proteins (MET, IGF-1R) and by increasing their transcription levels. Together, these results reveal that the stress hormone NE accelerates Afatinib resistance by increasing the expression of Cx32, which augments MET and IGF-1R levels in cancer cells and provides a promising therapeutic strategy against EGFR-TKI Afatinib resistance in NSCLC.
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Affiliation(s)
- Jie Xie
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Xiyan Wang
- Tumor Research Institute, Xinjiang Medical University Affiliated Tumor Hospital, Urumqi, Xinjiang, China
| | - Hui Ge
- Tumor Research Institute, Xinjiang Medical University Affiliated Tumor Hospital, Urumqi, Xinjiang, China
| | - Fuhua Peng
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Ningze Zheng
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Qin Wang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Liang Tao
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
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Kameritsch P, Kiemer F, Mannell H, Beck H, Pohl U, Pogoda K. PKA negatively modulates the migration enhancing effect of Connexin 43. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:828-838. [PMID: 30769008 DOI: 10.1016/j.bbamcr.2019.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 01/31/2019] [Accepted: 02/01/2019] [Indexed: 12/22/2022]
Abstract
Connexin 43 (Cx43) expression is associated with an increased cell migration and related changes of the actin cytoskeleton (enhanced filopodia formation). These effects are mediated by the C-terminal cytoplasmic part of Cx43 in a channel-independent manner. Since this part has been shown to interact with a variety of proteins and has multiple phosphorylation sites we analyzed here a potential role of the protein kinase A (PKA) for the Cx43 mediated increase in cell migration. Mutation of the PKA-phosphorylation site (substitution of three serines by alanine or glycine) resulted in a further increase in cell motility compared to wild-type Cx43, but with a loss of directionality. Likewise, cell motility was enhanced by PKA inhibition only in Cx43 expressing cells, while reduced in the presence of the PKA activator forskolin. In contrast, cell motility remained unaffected by stimulation with forskolin in cells expressing Cx43 with the mutated PKA phosphorylation site (Cx43-PKA) as well as in Cx-deficient cells. Moreover, PKA activation resulted in increased binding of PKA and VASP to Cx43 associated with an enhanced phosphorylation of VASP, an important regulatory protein of cell polarity and directed migration. Functionally, we could confirm these results in endothelial cells endogenously expressing Cx43. A Tat-Cx43 peptide containing the PKA phosphorylation site abolished the PKA dependent reduction in endothelial cell migration. Our results indicate that PKA dependent phosphorylation of Cx43 modulates cell motility and plays a pivotal role in regulating directed cell migration.
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Affiliation(s)
- Petra Kameritsch
- Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München and Munich University Hospital, Großhaderner Str. 9, 82152 Planegg, Martinsried, Germany; DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, Biedersteiner Str. 29, 80802 München, Germany.
| | - Felizitas Kiemer
- Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München and Munich University Hospital, Großhaderner Str. 9, 82152 Planegg, Martinsried, Germany.
| | - Hanna Mannell
- Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München and Munich University Hospital, Großhaderner Str. 9, 82152 Planegg, Martinsried, Germany.
| | - Heike Beck
- Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München and Munich University Hospital, Großhaderner Str. 9, 82152 Planegg, Martinsried, Germany.
| | - Ulrich Pohl
- Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München and Munich University Hospital, Großhaderner Str. 9, 82152 Planegg, Martinsried, Germany; DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, Biedersteiner Str. 29, 80802 München, Germany; Munich Cluster for Systems Neurology (SyNergy), Feodor-Lynen-Str. 17, 81377 München, Germany.
| | - Kristin Pogoda
- Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München and Munich University Hospital, Großhaderner Str. 9, 82152 Planegg, Martinsried, Germany; DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, Biedersteiner Str. 29, 80802 München, Germany.
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Sorgen PL, Trease AJ, Spagnol G, Delmar M, Nielsen MS. Protein⁻Protein Interactions with Connexin 43: Regulation and Function. Int J Mol Sci 2018; 19:E1428. [PMID: 29748463 PMCID: PMC5983787 DOI: 10.3390/ijms19051428] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 05/07/2018] [Accepted: 05/08/2018] [Indexed: 12/11/2022] Open
Abstract
Connexins are integral membrane building blocks that form gap junctions, enabling direct cytoplasmic exchange of ions and low-molecular-mass metabolites between adjacent cells. In the heart, gap junctions mediate the propagation of cardiac action potentials and the maintenance of a regular beating rhythm. A number of connexin interacting proteins have been described and are known gap junction regulators either through direct effects (e.g., kinases) or the formation of larger multifunctional complexes (e.g., cytoskeleton scaffold proteins). Most connexin partners can be categorized as either proteins promoting coupling by stimulating forward trafficking and channel opening or inhibiting coupling by inducing channel closure, internalization, and degradation. While some interactions have only been implied through co-localization using immunohistochemistry, others have been confirmed by biophysical methods that allow detection of a direct interaction. Our understanding of these interactions is, by far, most well developed for connexin 43 (Cx43) and the scope of this review is to summarize our current knowledge of their functional and regulatory roles. The significance of these interactions is further exemplified by demonstrating their importance at the intercalated disc, a major hub for Cx43 regulation and Cx43 mediated effects.
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Affiliation(s)
- Paul L Sorgen
- 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.
| | - Gaelle Spagnol
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Mario Delmar
- Leon H Charney Division of Cardiology, NYU School of Medicine, New York, NY 10016, USA.
| | - Morten S Nielsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark.
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