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Riquelme MA, Wang X, Acosta FM, Zhang J, Chavez J, Gu S, Zhao P, Xiong W, Zhang N, Li G, Srinivasan S, Ma C, Rao MK, Sun LZ, Zhang N, An Z, Jiang JX. Antibody-activation of connexin hemichannels in bone osteocytes with ATP release suppresses breast cancer and osteosarcoma malignancy. Cell Rep 2024; 43:114377. [PMID: 38889005 PMCID: PMC11380445 DOI: 10.1016/j.celrep.2024.114377] [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: 10/05/2023] [Revised: 05/02/2024] [Accepted: 05/31/2024] [Indexed: 06/20/2024] Open
Abstract
Bone tissue represents the most frequent site of cancer metastasis. We developed a hemichannel-activating antibody, Cx43-M2. Cx43-M2, directly targeting osteocytes in situ, activates osteocytic hemichannels and elevates extracellular ATP, thereby inhibiting the growth and migration of cultured breast and osteosarcoma cancer cells. Cx43-M2 significantly decreases breast cancer metastasis, osteosarcoma growth, and osteolytic activity, while improving survival rates in mice. The antibody's inhibition of breast cancer and osteosarcoma is dose dependent in both mouse and human cancer metastatic models. Furthermore, Cx43-M2 enhances anti-tumor immunity by increasing the population and activation of tumor-infiltrating immune-promoting effector T lymphocytes, while reducing immune-suppressive regulatory T cells. Our results suggest that the Cx43-M2 antibody, by activating Cx43 hemichannels and facilitating ATP release and purinergic signaling, transforms the cancer microenvironment from a supportive to a suppressive state. Collectively, our study underscores the potential of Cx43-M2 as a therapeutic for treating breast cancer bone metastasis and osteosarcoma.
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Affiliation(s)
- Manuel A Riquelme
- Departments of Biochemistry and Structural Biology, Microbiology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Xuewei Wang
- Departments of Biochemistry and Structural Biology, Microbiology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Francisca M Acosta
- Departments of Biochemistry and Structural Biology, Microbiology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Jingruo Zhang
- Departments of Biochemistry and Structural Biology, Microbiology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Jeffery Chavez
- Departments of Biochemistry and Structural Biology, Microbiology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Sumin Gu
- Departments of Biochemistry and Structural Biology, Microbiology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Peng Zhao
- The Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Wei Xiong
- The Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Ningyan Zhang
- The Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Guo Li
- Immunology & Molecular Genetics, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Saranya Srinivasan
- Immunology & Molecular Genetics, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Chaoyu Ma
- Immunology & Molecular Genetics, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Manjeet K Rao
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA; Cell Systems and Anatomy, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Lu-Zhe Sun
- Cell Systems and Anatomy, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Nu Zhang
- Immunology & Molecular Genetics, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA; South Texas Veterans Health Care System, San Antonio, TX 78229, USA
| | - Zhiqiang An
- The Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center, Houston, TX 77030, USA.
| | - Jean X Jiang
- Departments of Biochemistry and Structural Biology, Microbiology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA.
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Rengarajan A, Goldblatt HE, Beebe DJ, Virumbrales-Muñoz M, Boeldt DS. Immune cells and inflammatory mediators cause endothelial dysfunction in a vascular microphysiological system. LAB ON A CHIP 2024; 24:1808-1820. [PMID: 38363157 PMCID: PMC11022267 DOI: 10.1039/d3lc00824j] [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: 02/17/2024]
Abstract
Functional assessment of endothelium serves as an important indicator of vascular health and is compromised in vascular disorders including hypertension, atherosclerosis, and preeclampsia. Endothelial dysfunction in these cases is linked to dysregulation of the immune system involving both changes to immune cells and increased secretion of inflammatory cytokines. Herein, we utilize a well-established microfluidic device to generate a 3-dimensional vascular microphysiological system (MPS) consisting of a tubular blood vessel lined with human umbilical vein endothelial cells (HUVECs) to evaluate endothelial function measured via endothelial permeability and Ca2+ signaling. We evaluated the effect of a mixture of factors associated with inflammation and cardiovascular disease (TNFα, VEGF-A, IL-6 at 10 ng ml-1 each) on vascular MPS and inferred that inflammatory mediators contribute to endothelial dysfunction by disrupting the endothelial barrier over a 48 hour treatment and by diminishing coordinated Ca2+ activity over a 1 hour treatment. We also evaluated the effect of peripheral blood mononuclear cells (PBMCs) on endothelial permeability and Ca2+ signaling in the HUVEC MPS. HUVECs were co-cultured with PBMCs either directly wherein PBMCs passed through the lumen or indirectly with PBMCs embedded in the supporting collagen hydrogel. We revealed that phytohemagglutinin (PHA)-M activated PBMCs cause endothelial dysfunction in MPS both through increased permeability and decreased coordinated Ca2+ activity compared to non-activated PBMCs. Our MPS has potential applications in modeling cardiovascular disorders and screening for potential treatments using measures of endothelial function.
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Affiliation(s)
- Aishwarya Rengarajan
- Department of Obstetrics & Gynecology, University of Wisconsin-Madison, School of Medicine and Public Health, USA.
- Perinatal Research Laboratories, UnityPoint Health-Meriter Hospital, 202 South Park St. 7E, Madison, WI, 53715, USA
| | - Hannah E Goldblatt
- Department of Obstetrics & Gynecology, University of Wisconsin-Madison, School of Medicine and Public Health, USA.
- Perinatal Research Laboratories, UnityPoint Health-Meriter Hospital, 202 South Park St. 7E, Madison, WI, 53715, USA
| | - David J Beebe
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI, 53705, USA
- University of Wisconsin Carbone Cancer Center, Wisconsin Institutes for Medical Research, 1111 Highland Ave, Madison, WI, 53705, USA
- Department of Biomedical Engineering, Wisconsin Institutes for Medical Research, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI, 53705, USA
| | - María Virumbrales-Muñoz
- Department of Obstetrics & Gynecology, University of Wisconsin-Madison, School of Medicine and Public Health, USA.
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI, 53705, USA
- University of Wisconsin Carbone Cancer Center, Wisconsin Institutes for Medical Research, 1111 Highland Ave, Madison, WI, 53705, USA
| | - Derek S Boeldt
- Department of Obstetrics & Gynecology, University of Wisconsin-Madison, School of Medicine and Public Health, USA.
- Perinatal Research Laboratories, UnityPoint Health-Meriter Hospital, 202 South Park St. 7E, Madison, WI, 53715, USA
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3
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Totland MZ, Omori Y, Sørensen V, Kryeziu K, Aasen T, Brech A, Leithe E. Endocytic trafficking of connexins in cancer pathogenesis. Biochim Biophys Acta Mol Basis Dis 2023:166812. [PMID: 37454772 DOI: 10.1016/j.bbadis.2023.166812] [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: 02/06/2023] [Revised: 06/26/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
Gap junctions are specialized regions of the plasma membrane containing clusters of channels that provide for the diffusion of ions and small molecules between adjacent cells. A fundamental role of gap junctions is to coordinate the functions of cells in tissues. Cancer pathogenesis is usually associated with loss of intercellular communication mediated by gap junctions, which may affect tumor growth and the response to radio- and chemotherapy. Gap junction channels consist of integral membrane proteins termed connexins. In addition to their canonical roles in cell-cell communication, connexins modulate a range of signal transduction pathways via interactions with proteins such as β-catenin, c-Src, and PTEN. Consequently, connexins can regulate cellular processes such as cell growth, migration, and differentiation through both channel-dependent and independent mechanisms. Gap junctions are dynamic plasma membrane entities, and by modulating the rate at which connexins undergo endocytosis and sorting to lysosomes for degradation, cells rapidly adjust the level of gap junctions in response to alterations in the intracellular or extracellular milieu. Current experimental evidence indicates that aberrant trafficking of connexins in the endocytic system is intrinsically involved in mediating the loss of gap junctions during carcinogenesis. This review highlights the role played by the endocytic system in controlling connexin degradation, and consequently gap junction levels, and discusses how dysregulation of these processes contributes to the loss of gap junctions during cancer development. We also discuss the therapeutic implications of aberrant endocytic trafficking of connexins in cancer cells.
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Affiliation(s)
| | - Yasufumi Omori
- Department of Molecular and Tumour Pathology, Akita University Graduate School of Medicine, Akita, Japan
| | | | | | - 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, Barcelona, Spain
| | - Andreas Brech
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway; Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway; Section for Physiology and Cell Biology, Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
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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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5
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Applicability of Scrape Loading-Dye Transfer Assay for Non-Genotoxic Carcinogen Testing. Int J Mol Sci 2021; 22:ijms22168977. [PMID: 34445682 PMCID: PMC8396440 DOI: 10.3390/ijms22168977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/30/2021] [Accepted: 07/31/2021] [Indexed: 12/27/2022] Open
Abstract
Dysregulation of gap junction intercellular communication (GJIC) is recognized as one of the key hallmarks for identifying non-genotoxic carcinogens (NGTxC). Currently, there is a demand for in vitro assays addressing the gap junction hallmark, which would have the potential to eventually become an integral part of an integrated approach to the testing and assessment (IATA) of NGTxC. The scrape loading-dye transfer (SL-DT) technique is a simple assay for the functional evaluation of GJIC in various in vitro cultured mammalian cells and represents an interesting candidate assay. Out of the various techniques for evaluating GJIC, the SL-DT assay has been used frequently to assess the effects of various chemicals on GJIC in toxicological and tumor promotion research. In this review, we systematically searched the existing literature to gather papers assessing GJIC using the SL-DT assay in a rat liver epithelial cell line, WB-F344, after treating with chemicals, especially environmental and food toxicants, drugs, reproductive-, cardio- and neuro-toxicants and chemical tumor promoters. We discuss findings derived from the SL-DT assay with the known knowledge about the tumor-promoting activity and carcinogenicity of the assessed chemicals to evaluate the predictive capacity of the SL-DT assay in terms of its sensitivity, specificity and accuracy for identifying carcinogens. These data represent important information with respect to the applicability of the SL-DT assay for the testing of NGTxC within the IATA framework.
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Martins-Marques T, Catarino S, Gonçalves A, Miranda-Silva D, Gonçalves L, Antunes P, Coutinho G, Leite Moreira A, Falcão Pires I, Girão H. EHD1 Modulates Cx43 Gap Junction Remodeling Associated With Cardiac Diseases. Circ Res 2020; 126:e97-e113. [PMID: 32138615 DOI: 10.1161/circresaha.119.316502] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
RATIONALE Efficient communication between heart cells is vital to ensure the anisotropic propagation of electrical impulses, a function mainly accomplished by gap junctions (GJ) composed of Cx43 (connexin 43). Although the molecular mechanisms remain unclear, altered distribution and function of gap junctions have been associated with acute myocardial infarction and heart failure. OBJECTIVE A recent proteomic study from our laboratory identified EHD1 (Eps15 [endocytic adaptor epidermal growth factor receptor substrate 15] homology domain-containing protein 1) as a novel interactor of Cx43 in the heart. METHODS AND RESULTS In the present work, we demonstrate that knockdown of EHD1 impaired the internalization of Cx43, preserving gap junction-intercellular coupling in cardiomyocytes. Interaction of Cx43 with EHD1 was mediated by Eps15 and promoted by phosphorylation and ubiquitination of Cx43. Overexpression of wild-type EHD1 accelerated internalization of Cx43 and exacerbated ischemia-induced lateralization of Cx43 in isolated adult cardiomyocytes. In addition, we show that EHDs associate with Cx43 in human and murine failing hearts. CONCLUSIONS Overall, we identified EHDs as novel regulators of endocytic trafficking of Cx43, participating in the pathological remodeling of gap junctions, paving the way to innovative therapeutic strategies aiming at preserving intercellular communication in the heart.
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Affiliation(s)
- Tania Martins-Marques
- From the Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine (T.M.-M., S.C., L.C., P.A., G.C., H.G.), University of Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology (T.M.-M., S.C., H.G.), University of Coimbra, Portugal.,Clinical Academic Centre of Coimbra, CACC, Portugal (T.M-M., S.C., L.G., P.A., G.C., H.G.)
| | - Steve Catarino
- From the Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine (T.M.-M., S.C., L.C., P.A., G.C., H.G.), University of Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology (T.M.-M., S.C., H.G.), University of Coimbra, Portugal.,Clinical Academic Centre of Coimbra, CACC, Portugal (T.M-M., S.C., L.G., P.A., G.C., H.G.)
| | - Alexandre Gonçalves
- Department of Surgery and Physiology & Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Portugal (A.G., D.M.S., A.L.M., I.F.P.)
| | - Daniela Miranda-Silva
- Department of Surgery and Physiology & Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Portugal (A.G., D.M.S., A.L.M., I.F.P.)
| | - Lino Gonçalves
- Clinical Academic Centre of Coimbra, CACC, Portugal (T.M-M., S.C., L.G., P.A., G.C., H.G.)
| | - Pedro Antunes
- From the Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine (T.M.-M., S.C., L.C., P.A., G.C., H.G.), University of Coimbra, Portugal.,Clinical Academic Centre of Coimbra, CACC, Portugal (T.M-M., S.C., L.G., P.A., G.C., H.G.).,Cardiothoracic Surgery (P.A., G.C.), Coimbra Hospital and University Centre, Portugal
| | - Gonçalo Coutinho
- From the Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine (T.M.-M., S.C., L.C., P.A., G.C., H.G.), University of Coimbra, Portugal.,Clinical Academic Centre of Coimbra, CACC, Portugal (T.M-M., S.C., L.G., P.A., G.C., H.G.).,Cardiothoracic Surgery (P.A., G.C.), Coimbra Hospital and University Centre, Portugal
| | - Adelino Leite Moreira
- Department of Surgery and Physiology & Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Portugal (A.G., D.M.S., A.L.M., I.F.P.)
| | - Inês Falcão Pires
- Department of Surgery and Physiology & Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Portugal (A.G., D.M.S., A.L.M., I.F.P.)
| | - Henrique Girão
- From the Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine (T.M.-M., S.C., L.C., P.A., G.C., H.G.), University of Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology (T.M.-M., S.C., H.G.), University of Coimbra, Portugal.,Clinical Academic Centre of Coimbra, CACC, Portugal (T.M-M., S.C., L.G., P.A., G.C., H.G.)
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Totland MZ, Rasmussen NL, Knudsen LM, Leithe E. Regulation of gap junction intercellular communication by connexin ubiquitination: physiological and pathophysiological implications. Cell Mol Life Sci 2020; 77:573-591. [PMID: 31501970 PMCID: PMC7040059 DOI: 10.1007/s00018-019-03285-0] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 08/10/2019] [Accepted: 08/16/2019] [Indexed: 12/15/2022]
Abstract
Gap junctions consist of arrays of intercellular channels that enable adjacent cells to communicate both electrically and metabolically. Gap junctions have a wide diversity of physiological functions, playing critical roles in both excitable and non-excitable tissues. Gap junction channels are formed by integral membrane proteins called connexins. Inherited or acquired alterations in connexins are associated with numerous diseases, including heart failure, neuropathologies, deafness, skin disorders, cataracts and cancer. Gap junctions are highly dynamic structures and by modulating the turnover rate of connexins, cells can rapidly alter the number of gap junction channels at the plasma membrane in response to extracellular or intracellular cues. Increasing evidence suggests that ubiquitination has important roles in the regulation of endoplasmic reticulum-associated degradation of connexins as well as in the modulation of gap junction endocytosis and post-endocytic sorting of connexins to lysosomes. In recent years, researchers have also started to provide insights into the physiological roles of connexin ubiquitination in specific tissue types. This review provides an overview of the advances made in understanding the roles of connexin ubiquitination in the regulation of gap junction intercellular communication and discusses the emerging physiological and pathophysiological implications of these processes.
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Affiliation(s)
- Max Zachrisson Totland
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, 0424, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Nikoline Lander Rasmussen
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, 0424, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
- Department of Medical Biology, University of Tromsø, Tromsø, Norway
| | - Lars Mørland Knudsen
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, 0424, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Edward Leithe
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, 0424, Oslo, Norway.
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway.
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8
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Ji X, Chou X, Ge Z, Ding F, Gao H, Wu Q. Benzo[a
]pyrene-decreased gap junctional intercellular communication via calcium/calmodulin signaling increases apoptosis in TM4 cells. J Appl Toxicol 2018; 38:1091-1103. [DOI: 10.1002/jat.3618] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/07/2018] [Accepted: 02/07/2018] [Indexed: 12/12/2022]
Affiliation(s)
- Xiaoli Ji
- School of Public Health; Fudan University and Key Laboratory of Public Health Safety, Ministry of Education; 130 Dong An Road Shanghai 200032 China
| | - Xin Chou
- School of Public Health; Fudan University and Key Laboratory of Public Health Safety, Ministry of Education; 130 Dong An Road Shanghai 200032 China
| | - Zehe Ge
- School of Public Health; Fudan University and Key Laboratory of Public Health Safety, Ministry of Education; 130 Dong An Road Shanghai 200032 China
| | - Fan Ding
- School of Public Health; Fudan University and Key Laboratory of Public Health Safety, Ministry of Education; 130 Dong An Road Shanghai 200032 China
| | - Hui Gao
- School of Public Health; Fudan University and Key Laboratory of Public Health Safety, Ministry of Education; 130 Dong An Road Shanghai 200032 China
| | - Qing Wu
- School of Public Health; Fudan University and Key Laboratory of Public Health Safety, Ministry of Education; 130 Dong An Road Shanghai 200032 China
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9
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Li H, Spagnol G, Zheng L, Stauch KL, Sorgen PL. Regulation of Connexin43 Function and Expression by Tyrosine Kinase 2. J Biol Chem 2016; 291:15867-80. [PMID: 27235399 DOI: 10.1074/jbc.m116.727008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Indexed: 11/06/2022] Open
Abstract
Connexin43 (Cx43) assembly and degradation, the regulation of electrical and metabolic coupling, as well as modulating the interaction with other proteins, involve phosphorylation. Here, we identified and characterized the biological significance of a novel tyrosine kinase that phosphorylates Cx43, tyrosine kinase 2 (Tyk2). Activation of Tyk2 led to a decrease in Cx43 gap junction communication by increasing the turnover rate of Cx43 from the plasma membrane. Tyk2 directly phosphorylated Cx43 residues Tyr-247 and Tyr-265, leading to indirect phosphorylation on residues Ser-279/Ser-282 (MAPK) and Ser-368 (PKC). Although this phosphorylation pattern is similar to what has been observed following Src activation, the response caused by Tyk2 occurred when Src was inactive in NRK cells. Knockdown of Tyk2 at the permissive temperature (active v-Src) in LA-25 cells decreased Cx43 phosphorylation, indicating that although activation of Tyk2 and v-Src leads to phosphorylation of the same Cx43CT residues, they are not identical in level at each site. Additionally, angiotensin II activation of Tyk2 increased the intracellular protein level of Cx43 via STAT3. These findings indicate that, like Src, Tyk2 can also inhibit gap junction communication by phosphorylating Cx43.
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Affiliation(s)
- Hanjun Li
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Gaelle Spagnol
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Li Zheng
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Kelly L Stauch
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Paul L Sorgen
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
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10
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Leithe E. Regulation of connexins by the ubiquitin system: Implications for intercellular communication and cancer. Biochim Biophys Acta Rev Cancer 2016; 1865:133-46. [DOI: 10.1016/j.bbcan.2016.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 01/15/2016] [Accepted: 02/04/2016] [Indexed: 12/31/2022]
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11
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Boeldt DS, Grummer MA, Yi F, Magness RR, Bird IM. Phosphorylation of Ser-279/282 and Tyr-265 positions on Cx43 as possible mediators of VEGF-165 inhibition of pregnancy-adapted Ca2+ burst function in ovine uterine artery endothelial cells. Mol Cell Endocrinol 2015; 412:73-84. [PMID: 26033246 PMCID: PMC4516676 DOI: 10.1016/j.mce.2015.05.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 05/26/2015] [Accepted: 05/26/2015] [Indexed: 10/23/2022]
Abstract
Normal pregnancy requires increased uterine endothelial cell driven vasodilation that is related to increases in sustained Ca2+ signaling via increased connexin 43 (Cx43) gap junction function. Preeclampsia, a hypertensive disorder of pregnancy associated with endothelial dysfunction, is also linked with down regulation of Ca2+ driven vasodilator production and increased levels of vascular endothelial growth factor (VEGF). Cx43 function can be acutely down-regulated by phosphorylation of multiple inhibitory residues and VEGF is known to promote phosphorylation of Cx43. Herein, we show that VEGF-165 promotes Cx43 phosphorylation at Ser-279/282 and Tyr-265 residues and blocks pregnancy-adapted Ca2+ signaling in ovine uterine artery endothelial cells (UAEC). Pharmacological Src and ERK kinase pathway inhibitors (PP2 and U0126) reverse these phosphorylations and rescue Ca2+ signaling. We also report a nutraceutical Src inhibitor, t10,c12 conjugated linoleic acid (10,12 CLA), rescues Ca2+ signaling in UAEC and therefore may have therapeutic potential for preeclampsia.
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Affiliation(s)
- Derek S Boeldt
- Perinatal Research Laboratories, Department of Obstetrics and Gynecology, University of Wisconsin - Madison, School Medicine and Public Health, Madison, WI 53715, USA.
| | - Mary A Grummer
- Perinatal Research Laboratories, Department of Obstetrics and Gynecology, University of Wisconsin - Madison, School Medicine and Public Health, Madison, WI 53715, USA
| | - FuXian Yi
- Perinatal Research Laboratories, Department of Obstetrics and Gynecology, University of Wisconsin - Madison, School Medicine and Public Health, Madison, WI 53715, USA
| | - Ronald R Magness
- Perinatal Research Laboratories, Department of Obstetrics and Gynecology, University of Wisconsin - Madison, School Medicine and Public Health, Madison, WI 53715, USA; Department of Pediatrics, University of Wisconsin - Madison, School Medicine and Public Health, Madison, WI 53715, USA; Department of Animal Sciences, University of Wisconsin - Madison, WI 53715, USA
| | - Ian M Bird
- Perinatal Research Laboratories, Department of Obstetrics and Gynecology, University of Wisconsin - Madison, School Medicine and Public Health, Madison, WI 53715, USA; Department of Pediatrics, University of Wisconsin - Madison, School Medicine and Public Health, Madison, WI 53715, USA
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12
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Li H, Spagnol G, Naslavsky N, Caplan S, Sorgen PL. TC-PTP directly interacts with connexin43 to regulate gap junction intercellular communication. J Cell Sci 2014; 127:3269-79. [PMID: 24849651 DOI: 10.1242/jcs.145193] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Protein kinases have long been reported to regulate connexins; however, little is known about the involvement of phosphatases in the modulation of intercellular communication through gap junctions and the subsequent downstream effects on cellular processes. Here, we identify an interaction between the T-cell protein tyrosine phosphatase (TC-PTP, officially known as PTPN2) and the carboxyl terminus of connexin43 (Cx43, officially known as GJA1). Two cell lines, normal rat kidney (NRK) cells endogenously expressing Cx43 and an NRK-derived cell line expressing v-Src with temperature-sensitive activity, were used to demonstrate that EGF and v-Src stimulation, respectively, induced TC-PTP to colocalize with Cx43 at the plasma membrane. Cell biology experiments using phospho-specific antibodies and biophysical assays demonstrated that the interaction is direct and that TC-PTP dephosphorylates Cx43 residues Y247 and Y265, but does not affect v-Src. Transfection of TC-PTP also indirectly led to the dephosphorylation of Cx43 S368, by inactivating PKCα and PKCδ, with no effect on the phosphorylation of S279 and S282 (MAPK-dependent phosphorylation sites). Dephosphorylation maintained Cx43 gap junctions at the plaque and partially reversed the channel closure caused by v-Src-mediated phosphorylation of Cx43. Understanding dephosphorylation, along with the well-documented roles of Cx43 phosphorylation, might eventually lead to methods to modulate the regulation of gap junction channels, with potential benefits for human health.
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Affiliation(s)
- Hanjun Li
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Gaelle Spagnol
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Naava Naslavsky
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Steve Caplan
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Paul L Sorgen
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
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13
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Connexins: mechanisms regulating protein levels and intercellular communication. FEBS Lett 2014; 588:1212-20. [PMID: 24457202 DOI: 10.1016/j.febslet.2014.01.013] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 01/10/2014] [Accepted: 01/13/2014] [Indexed: 11/21/2022]
Abstract
Intercellular communication can occur through gap junction channels, which are comprised of connexin proteins. Therefore, levels of connexins can directly correlate with gap junctional intercellular communication. Because gap junctions have a critical role in maintaining cellular homeostasis, the regulation of connexin protein levels is important. In the connexin life cycle, connexin protein levels can be modified through differential gene transcription or altered through trafficking and degradation mechanisms. More recently, significant attention has been directed to the pathways that cells utilize to increase or decrease connexin levels and thus indirectly, gap junctional communication. Here, we review the studies revealing the mechanisms that affect connexin protein levels and gap junctional intercellular communication.
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Dunn CA, Lampe PD. Injury-triggered Akt phosphorylation of Cx43: a ZO-1-driven molecular switch that regulates gap junction size. J Cell Sci 2013; 127:455-64. [PMID: 24213533 DOI: 10.1242/jcs.142497] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The proteins that form vertebrate gap junctions, the connexins, are highly regulated and have short (<2 hour) half-lives. Phosphorylation of connexin43 (Cx43) affects gap junction assembly, channel gating and turnover. After finding dramatic effects on gap junctions with Akt inhibitors, we created an antibody specific for Cx43 phosphorylated on S373, a potential Akt substrate. We found S373 phosphorylation in cells and skin or heart almost exclusively in larger gap-junctional structures that increased dramatically after wounding or hypoxia. We were able to mechanistically show that Akt-dependent phosphorylation of S373 increases gap junction size and communication by completely eliminating the interaction between Cx43 and ZO-1. Thus, phosphorylation on S373 acts as a molecular 'switch' to rapidly increase gap-junctional communication, potentially leading to initiation of activation and migration of keratinocytes or ischemic injury response in the skin and the heart, respectively.
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Affiliation(s)
- Clarence A Dunn
- Translational Research Program, Human Biology and Public Health Sciences Divisions, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA 98109, USA
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15
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Axelsen LN, Calloe K, Holstein-Rathlou NH, Nielsen MS. Managing the complexity of communication: regulation of gap junctions by post-translational modification. Front Pharmacol 2013; 4:130. [PMID: 24155720 PMCID: PMC3804956 DOI: 10.3389/fphar.2013.00130] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 09/30/2013] [Indexed: 12/21/2022] Open
Abstract
Gap junctions are comprised of connexins that form cell-to-cell channels which couple neighboring cells to accommodate the exchange of information. The need for communication does, however, change over time and therefore must be tightly controlled. Although the regulation of connexin protein expression by transcription and translation is of great importance, the trafficking, channel activity and degradation are also under tight control. The function of connexins can be regulated by several post translational modifications, which affect numerous parameters; including number of channels, open probability, single channel conductance or selectivity. The most extensively investigated post translational modifications are phosphorylations, which have been documented in all mammalian connexins. Besides phosphorylations, some connexins are known to be ubiquitinated, SUMOylated, nitrosylated, hydroxylated, acetylated, methylated, and γ-carboxyglutamated. The aim of the present review is to summarize our current knowledge of post translational regulation of the connexin family of proteins.
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Affiliation(s)
- Lene N Axelsen
- Department of Biomedical Sciences and The Danish National Research Foundation Centre for Cardiac Arrhythmia, Faculty of Health and Medical Sciences, University of Copenhagen Copenhagen, Denmark
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16
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Cochrane K, Su V, Lau AF. The connexin43-interacting protein, CIP85, mediates the internalization of connexin43 from the plasma membrane. ACTA ACUST UNITED AC 2013; 20:53-66. [PMID: 23586710 DOI: 10.3109/15419061.2013.784745] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CIP85 was previously identified as a connexin43 (Cx43)-interacting protein that is ubiquitously expressed in multiple mammalian tissues and cell types. The interaction between the SH3 domain of CIP85 and a proline-rich region of Cx43 has previously been associated with an increased rate of Cx43 turnover through lysosomal mechanisms. This report presents biochemical and immunofluorescence evidence that overexpression of CIP85 reduced the presence of Cx43 in gap junction plaques at the plasma membrane. Furthermore, this effect was dependent upon the interaction of CIP85 with Cx43 at the plasma membrane. These results indicate that CIP85 increases Cx43 turnover by accelerating the internalization of Cx43 from the plasma membrane. CIP85 was also observed to interact with clathrin, which suggested a role for CIP85 in the clathrin-mediated internalization of Cx43.
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Affiliation(s)
- Kimberly Cochrane
- Cancer Biology Program, University of Hawaii Cancer Center, Honolulu, HI, USA
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17
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Degradation of connexins through the proteasomal, endolysosomal and phagolysosomal pathways. J Membr Biol 2012; 245:389-400. [PMID: 22772442 DOI: 10.1007/s00232-012-9461-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 06/20/2012] [Indexed: 01/23/2023]
Abstract
Connexins comprise gap junction channels, which create a direct conduit between the cytoplasms of adjacent cells and provide for intercellular communication. Therefore, the level of total cellular connexin protein can have a direct influence on the level of intercellular communication. Control of connexin protein levels can occur through different mechanisms during the connexin life cycle, such as by regulation of connexin gene expression and turnover of existing protein. The degradation of connexins has been extensively studied, revealing proteasomal, endolysosomal and more recently autophagosomal degradation mechanisms that modulate connexin turnover and, subsequently, affect intercellular communication. Here, we review the current knowledge of connexin degradation pathways.
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18
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Kjenseth A, Fykerud TA, Sirnes S, Bruun J, Yohannes Z, Kolberg M, Omori Y, Rivedal E, Leithe E. The gap junction channel protein connexin 43 is covalently modified and regulated by SUMOylation. J Biol Chem 2012; 287:15851-61. [PMID: 22411987 PMCID: PMC3346107 DOI: 10.1074/jbc.m111.281832] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 03/02/2012] [Indexed: 11/06/2022] Open
Abstract
SUMOylation is a posttranslational modification in which a member of the small ubiquitin-like modifier (SUMO) family of proteins is conjugated to lysine residues in specific target proteins. Most known SUMOylation target proteins are located in the nucleus, but there is increasing evidence that SUMO may also be a key determinant of many extranuclear processes. Gap junctions consist of arrays of intercellular channels that provide direct transfer of ions and small molecules between adjacent cells. Gap junction channels are formed by integral membrane proteins called connexins, of which the best-studied isoform is connexin 43 (Cx43). Here we show that Cx43 is posttranslationally modified by SUMOylation. The data suggest that the SUMO system regulates the Cx43 protein level and the level of functional Cx43 gap junctions at the plasma membrane. Cx43 was found to be modified by SUMO-1, -2, and -3. Evidence is provided that the membrane-proximal lysines at positions 144 and 237, located in the Cx43 intracellular loop and C-terminal tail, respectively, act as SUMO conjugation sites. Mutations of lysine 144 or lysine 237 resulted in reduced Cx43 SUMOylation and reduced Cx43 protein and gap junction levels. Altogether, these data identify Cx43 as a SUMOylation target protein and represent the first evidence that gap junctions are regulated by the SUMO system.
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Affiliation(s)
- Ane Kjenseth
- From the Department of Cancer Prevention, Institute for Cancer Research, Oslo University Hospital and
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0310 Oslo, Norway and
| | - Tone A. Fykerud
- From the Department of Cancer Prevention, Institute for Cancer Research, Oslo University Hospital and
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0310 Oslo, Norway and
| | - Solveig Sirnes
- From the Department of Cancer Prevention, Institute for Cancer Research, Oslo University Hospital and
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0310 Oslo, Norway and
| | - Jarle Bruun
- From the Department of Cancer Prevention, Institute for Cancer Research, Oslo University Hospital and
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0310 Oslo, Norway and
| | - Zeremariam Yohannes
- From the Department of Cancer Prevention, Institute for Cancer Research, Oslo University Hospital and
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0310 Oslo, Norway and
| | - Matthias Kolberg
- From the Department of Cancer Prevention, Institute for Cancer Research, Oslo University Hospital and
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0310 Oslo, Norway and
| | - Yasufumi Omori
- the Department of Molecular and Tumour Pathology, Akita University School of Medicine, Hondo 010-8543, Akita, Japan
| | - Edgar Rivedal
- From the Department of Cancer Prevention, Institute for Cancer Research, Oslo University Hospital and
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0310 Oslo, Norway and
| | - Edward Leithe
- From the Department of Cancer Prevention, Institute for Cancer Research, Oslo University Hospital and
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0310 Oslo, Norway and
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19
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Su V, Lau AF. Ubiquitination, intracellular trafficking, and degradation of connexins. Arch Biochem Biophys 2012; 524:16-22. [PMID: 22239989 DOI: 10.1016/j.abb.2011.12.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 12/27/2011] [Accepted: 12/28/2011] [Indexed: 12/19/2022]
Abstract
Gap junction channels provide a conduit for communication between neighboring cells. The function of gap junction channels is regulated by posttranslational modifications of connexins, the proteins that comprise these channels. Ubiquitination of connexins has increasingly been viewed as one mechanism by which cells regulate the level of connexins present in cells, as well as the corresponding intercellular communication. Here we review the current knowledge of connexin ubiquitination and the effects this may have on gap junctional communication.
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Affiliation(s)
- Vivian Su
- Cancer Biology Program, University of Hawaii Cancer Center, University of Hawaii at Manoa, Honolulu, HI 96813, USA.
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20
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Fykerud TA, Kjenseth A, Schink KO, Sirnes S, Bruun J, Omori Y, Brech A, Rivedal E, Leithe E. Smad ubiquitination regulatory factor-2 controls gap junction intercellular communication by modulating endocytosis and degradation of connexin43. J Cell Sci 2012; 125:3966-76. [DOI: 10.1242/jcs.093500] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Gap junctions consist of arrays of intercellular channels that enable adjacent cells to communicate both electrically and metabolically. Gap junction channels are made of a family of integral membrane proteins called connexins, of which the best-studied member is connexin43. Gap junctions are dynamic plasma membrane domains, and connexin43 has a high turnover rate in most tissue types. However, the mechanisms involved in the regulation of connexin43 endocytosis and transport to lysosomes are still poorly understood. Here, we demonstrate by live-cell imaging analysis that treatment of cells with 12-O-tetradecanoylphorbol 13-acetate (TPA) induces endocytosis of subdomains of connexin43 gap junctions. The internalized, connexin43-enriched vesicles were found to fuse with early endosomes, which was followed by transport of connexin43 to the lumen of early endosomes. The HECT E3 ubiquitin ligase smad ubiquitination regulatory factor-2 (Smurf2) was found to be recruited to connexin43 gap junctions in response to TPA treatment. Depletion of Smurf2 by small interfering RNA (siRNA) resulted in enhanced levels of connexin43 gap junctions between adjacent cells and increased gap junction intercellular communication. Smurf2 depletion also counteracted the TPA-induced endocytosis and degradation of connexin43. Collectively, these data identify Smurf2 as a novel regulator of connexin43 gap junctions.
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Leithe E, Sirnes S, Fykerud T, Kjenseth A, Rivedal E. Endocytosis and post-endocytic sorting of connexins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1870-9. [PMID: 21996040 DOI: 10.1016/j.bbamem.2011.09.029] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 09/19/2011] [Accepted: 09/28/2011] [Indexed: 12/15/2022]
Abstract
The connexins constitute a family of integral membrane proteins that form intercellular channels, enabling adjacent cells in solid tissues to directly exchange ions and small molecules. These channels assemble into distinct plasma membrane domains known as gap junctions. Gap junction intercellular communication plays critical roles in numerous cellular processes, including control of cell growth and differentiation, maintenance of tissue homeostasis and embryonic development. Gap junctions are dynamic plasma membrane domains, and there is increasing evidence that modulation of endocytosis and post-endocytic trafficking of connexins are important mechanisms for regulating the level of functional gap junctions at the plasma membrane. The emerging picture is that multiple pathways exist for endocytosis and sorting of connexins to lysosomes, and that these pathways are differentially regulated in response to physiological and pathophysiological stimuli. Recent studies suggest that endocytosis and lysosomal degradation of connexins is controlled by a complex interplay between phosphorylation and ubiquitination. This review summarizes recent progress in understanding the molecular mechanisms involved in endocytosis and post-endocytic sorting of connexins, and the relevance of these processes to the regulation of gap junction intercellular communication under normal and pathophysiological conditions. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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Affiliation(s)
- Edward Leithe
- Department of Cancer Prevention, Oslo University Hospital, Oslo, Norway
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22
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Mollerup S, Hofgaard JP, Braunstein TH, Kjenseth A, Leithe E, Rivedal E, Holstein-Rathlou NH, Nielsen MS. Norepinephrine inhibits intercellular coupling in rat cardiomyocytes by ubiquitination of connexin43 gap junctions. ACTA ACUST UNITED AC 2011; 18:57-65. [DOI: 10.3109/15419061.2011.611920] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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23
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EphB signaling inhibits gap junctional intercellular communication and synchronized contraction in cultured cardiomyocytes. Basic Res Cardiol 2011; 106:1057-68. [DOI: 10.1007/s00395-011-0219-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 08/04/2011] [Accepted: 08/22/2011] [Indexed: 12/20/2022]
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Lee CH, Chen IH, Lee CR, Chi CH, Tsai MC, Tsai JL, Lin HF. Inhibition of gap junctional Intercellular communication in WB-F344 rat liver epithelial cells by triphenyltin chloride through MAPK and PI3-kinase pathways. J Occup Med Toxicol 2010; 5:17. [PMID: 20591183 PMCID: PMC2904784 DOI: 10.1186/1745-6673-5-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Accepted: 06/30/2010] [Indexed: 11/10/2022] Open
Abstract
Background Organotin compounds (OTCs) have been widely used as stabilizers in the production of plastic, agricultural pesticides, antifoulant plaints and wood preservation. The toxicity of triphenyltin (TPT) compounds was known for their embryotoxic, neurotoxic, genotoxic and immunotoxic effects in mammals. The carcinogenicity of TPT was not well understood and few studies had discussed the effects of OTCs on gap junctional intercellular communication (GJIC) of cells. Method In the present study, the effects of triphenyltin chloride (TPTC) on GJIC in WB-F344 rat liver epithelial cells were evaluated, using the scrape-loading dye transfer technique. Results TPTC inhibited GJIC after a 30-min exposure in a concentration- and time-dependent manner. Pre-incubation of cells with the protein kinase C (PKC) inhibitor did not modify the response, but the specific MEK 1 inhibitor PD98059 and PI3K inhibitor LY294002 decreased substantially the inhibition of GJIC by TPTC. After WB-F344 cells were exposed to TPTC, phosphorylation of Cx43 increased as seen in Western blot analysis. Conclusions These results show that TPTC inhibits GJIC in WB-F344 rat liver epithelial cells by altering the Cx43 protein expression through both MAPK and PI3-kinase pathways.
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Affiliation(s)
- Chung-Hsun Lee
- Graduate Institute of Occupational Safety and Health, College of Health Science, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
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Leithe E, Kjenseth A, Bruun J, Sirnes S, Rivedal E. Inhibition of connexin 43 gap junction channels by the endocrine disruptor ioxynil. Toxicol Appl Pharmacol 2010; 247:10-7. [PMID: 20510257 DOI: 10.1016/j.taap.2010.05.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 05/04/2010] [Accepted: 05/11/2010] [Indexed: 10/19/2022]
Abstract
Gap junctions are intercellular plasma membrane domains containing channels that mediate transport of ions, metabolites and small signaling molecules between adjacent cells. Gap junctions play important roles in a variety of cellular processes, including regulation of cell growth and differentiation, maintenance of tissue homeostasis and embryogenesis. The constituents of gap junction channels are a family of trans-membrane proteins called connexins, of which the best-studied is connexin 43. Connexin 43 functions as a tumor suppressor protein in various tissue types and is frequently dysregulated in human cancers. The pesticide ioxynil has previously been shown to act as an endocrine disrupting chemical and has multiple effects on the thyroid axis. Furthermore, both ioxynil and its derivative ioxynil octanoate have been reported to induce tumors in animal bioassays. However, the molecular mechanisms underlying the possible tumorigenic effects of these compounds are unknown. In the present study we show that ioxynil and ioxynil octanoate are strong inhibitors of connexin 43 gap junction channels. Both compounds induced rapid loss of connexin 43 gap junctions at the plasma membrane and increased connexin 43 degradation. Ioxynil octanoate, but not ioxynil, was found to be a strong activator of ERK1/2. The compounds also had different effects on the phosphorylation status of connexin 43. Taken together, the data show that ioxynil and ioxynil octanoate are potent inhibitors of intercellular communication via gap junctions.
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Affiliation(s)
- Edward Leithe
- Department of Cancer Prevention, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital and Centre for Cancer Biomedicine, University of Oslo, Oslo, Norway
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26
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Carette D, Gilleron J, Segretain D, Pointis G. Heteromeric connexin 43/connexin 33 complex endocytosis: A connexin phosphorylation independent mechanism. Biochimie 2010; 92:555-9. [DOI: 10.1016/j.biochi.2010.02.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Accepted: 02/02/2010] [Indexed: 10/19/2022]
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Langlois S, Cowan KN, Shao Q, Cowan BJ, Laird DW. The tumor-suppressive function of Connexin43 in keratinocytes is mediated in part via interaction with caveolin-1. Cancer Res 2010; 70:4222-32. [PMID: 20406988 DOI: 10.1158/0008-5472.can-09-3281] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Connexin43 (Cx43) is known to have tumor-suppressive effects, but the underlying mechanisms are still poorly understood. In keratinocytes, we previously showed that the COOH-terminal domain of Cx43 directly interacts with the tumor suppressor Cav-1. We now show that rat epidermal keratinocytes (REK) that are reduced in Cx43 present features of epithelial-to-mesenchymal transition and are more invasive than their control counterparts, whereas overexpression of Cx43 inhibited the 12-O-tetradecanoyl-phorbol-13-acetate (TPA)- and epidermal growth factor (EGF)-induced invasive properties. Carbenoxolone did not alter the inhibitory effect of Cx43 against TPA- and EGF-induced cell invasion, indicating the involvement of a gap junctional intercellular communication-independent mechanism. Interestingly, the association of Cx43 with Cav-1 was found to be reduced after TPA and EGF treatment. Accordingly, the colocalization of Cx43 with Cav-1 was diminished in cells from a human epidermal squamous cell carcinoma, as well as in sections from human keratinocyte tumors, suggesting that Cx43/Cav-1 interaction plays a protective role against keratinocyte transformation. As opposed to cells that overexpress Cx43-GFP, invasion could be induced in rat epidermal keratinocytes that overexpressed a GFP-tagged truncated mutant of Cx43 (Delta244-GFP) that we previously showed not to interact with Cav-1, as well as in cells that overexpressed Cx43-GFP but were reduced in Cav-1. Our data show that Cx43 possesses tumor-suppressive properties in keratinocytes and provide the first evidence that the Cx43/Cav-1 interaction is altered in keratinocyte transformation processes, as well as in human keratinocyte tumors, and that this association might play a role in Cx43-mediated tumor suppression.
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Affiliation(s)
- Stéphanie Langlois
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
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28
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Leithe E, Kjenseth A, Sirnes S, Stenmark H, Brech A, Rivedal E. Ubiquitylation of the gap junction protein connexin-43 signals its trafficking from early endosomes to lysosomes in a process mediated by Hrs and Tsg101. J Cell Sci 2009; 122:3883-93. [PMID: 19808888 DOI: 10.1242/jcs.053801] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Gap junctions are dynamic plasma membrane domains, and their protein constituents, the connexins, have a high turnover rate in most tissue types. However, the molecular mechanisms involved in degradation of gap junctions have remained largely unknown. Here, we show that ubiquitin is strongly relocalized to connexin-43 (Cx43; also known as Gja1) gap junction plaques in response to activation of protein kinase C. Cx43 remained ubiquitylated during its transition to a Triton X-100-soluble state and along its trafficking to early endosomes. Following internalization, Cx43 partly colocalized with the ubiquitin-binding proteins Hrs (hepatocyte growth factor-regulated tyrosine kinase substrate; also known as Hgs) and Tsg101 (tumor susceptibility gene 101). Depletion of Hrs or Tsg101 by small interfering RNA abrogated trafficking of Cx43 from early endosomes to lysosomes. Under these conditions, Cx43 was able to undergo dephosphorylation and deubiquitylation, locate to the plasma membrane and form functional gap junctions. Simultaneous depletion of Hrs and Tsg101 caused accumulation of a phosphorylated and ubiquitylated subpopulation of Cx43 in early endosomes and in hybrid organelles between partly degraded annular gap junctions and endosomes. Collectively, these data reveal a central role of early endosomes in sorting of ubiquitylated Cx43, and identify Hrs and Tsg101 as crucial regulators of trafficking of Cx43 to lysosomes.
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Affiliation(s)
- Edward Leithe
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo and Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Montebello, Oslo, Norway.
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29
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Interplay between PKC and the MAP kinase pathway in Connexin43 phosphorylation and inhibition of gap junction intercellular communication. Biochem Biophys Res Commun 2009; 382:41-5. [PMID: 19258009 DOI: 10.1016/j.bbrc.2009.02.141] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Accepted: 02/21/2009] [Indexed: 11/22/2022]
Abstract
Gap junction channels are made of a family proteins called connexins. The best-studied type of connexin, Connexin43 (Cx43), is phosphorylated at several sites in its C-terminus. The tumor-promoting phorbol ester TPA strongly inhibits Cx43 gap junction channels. In this study we have investigated mechanisms involved in TPA-induced phosphorylation of Cx43 and inhibition of gap junction channels. The data show that TPA-induced inhibition of gap junction intercellular communication (GJIC) is dependent on both PKC and the MAP kinase pathway. The data suggest that PKC-induced activation of MAP kinase partly involves Src-independent trans-activation of the EGF receptor, and that TPA-induced shift in SDS-PAGE gel mobility of Cx43 is caused by MAP kinase phosphorylation, whereas phosphorylation of S368 by PKC does not alter gel migration of Cx43. We also show that TPA, in addition to phosphorylation of S368, also induces phosphorylation of S255 and S262, in a MAP kinase-dependent manner. The data add to our understanding of the molecular mechanisms involved in the interplay between signaling pathways in regulation of GJIC.
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