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Gaete PS, Kumar D, Fernandez CI, Valdez Capuccino JM, Bhatt A, Jiang W, Lin YC, Liu Y, Harris AL, Luo YL, Contreras JE. Large-pore connexin hemichannels function like molecule transporters independent of ion conduction. Proc Natl Acad Sci U S A 2024; 121:e2403903121. [PMID: 39116127 DOI: 10.1073/pnas.2403903121] [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: 03/14/2024] [Accepted: 07/05/2024] [Indexed: 08/10/2024] Open
Abstract
Connexin hemichannels were identified as the first members of the eukaryotic large-pore channel family that mediate permeation of both atomic ions and small molecules between the intracellular and extracellular environments. The conventional view is that their pore is a large passive conduit through which both ions and molecules diffuse in a similar manner. In stark contrast to this notion, we demonstrate that the permeation of ions and of molecules in connexin hemichannels can be uncoupled and differentially regulated. We find that human connexin mutations that produce pathologies and were previously thought to be loss-of-function mutations due to the lack of ionic currents are still capable of mediating the passive transport of molecules with kinetics close to those of wild-type channels. This molecular transport displays saturability in the micromolar range, selectivity, and competitive inhibition, properties that are tuned by specific interactions between the permeating molecules and the N-terminal domain that lies within the pore-a general feature of large-pore channels. We propose that connexin hemichannels and, likely, other large-pore channels, are hybrid channel/transporter-like proteins that might switch between these two modes to promote selective ion conduction or autocrine/paracrine molecular signaling in health and disease processes.
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Affiliation(s)
- Pablo S Gaete
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA 95616
| | - Deepak Kumar
- Department of Biotechnology and Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA 91766
| | - Cynthia I Fernandez
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA 95616
| | - Juan M Valdez Capuccino
- Department of Pharmacology, Physiology, and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103
| | - Aashish Bhatt
- Department of Biotechnology and Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA 91766
| | - Wenjuan Jiang
- Department of Biotechnology and Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA 91766
| | - Yi-Chun Lin
- Department of Biotechnology and Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA 91766
| | - Yu Liu
- Department of Pharmacology, Physiology, and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103
| | - Andrew L Harris
- Department of Pharmacology, Physiology, and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103
| | - Yun L Luo
- Department of Biotechnology and Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA 91766
| | - Jorge E Contreras
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA 95616
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2
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Frydrych K, Wolak D, Hrabia A. Tamoxifen-induced alterations in the expression of connexin 43 in the chicken ovary. Theriogenology 2024; 229:8-15. [PMID: 39142068 DOI: 10.1016/j.theriogenology.2024.08.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 07/22/2024] [Accepted: 08/09/2024] [Indexed: 08/16/2024]
Abstract
Connexin 43 (Cx43) is a gap junction protein that participates in small molecule exchange between adjacent cells. It is a predominant Cx within the mammalian ovary, where is associated with proper follicle development. The expression and regulation of Cx43 in the chicken ovary is largely unknown. The aim of the present study was to examine the expression of the Cx43 gene (GJA1) and protein as well as the immunolocalization of Cx43 in the laying hen ovary in relation to follicle development, and to examine how tamoxifen (TMX; an estrogen receptor modulator) treatment affects these factors. qRT-PCR and western blotting demonstrated differences in Cx43 mRNA transcript and protein abundances in ovarian white follicles, yellowish follicles, small yellow follicles, and the largest yellow preovulatory follicles (F3-F1). In general, Cx43 was more abundant in hierarchical than prehierarchical follicles and in granulosa cells compared with theca cells. Further, the response to TMX treatment depended on the stage of follicle development and the layer of the follicular wall. Ovarian regression following TMX treatment was accompanied by an increase in Cx43 expression in most ovarian tissues, which may impact the formation and function of Cx43 hemichannels. Overall, our results showed, for the first time, the differences in Cx43 mRNA and protein levels between ovarian follicles, suggesting the potential involvement of this gap junction protein in the regulation of ovarian follicle development and function. In addition, the results indicate a possible role for estradiol in regulation of Cx43 transcription and/or translation in the chicken ovary. Understanding the contribution of Cx43 in mechanisms underlying ovarian follicle development may be of considerable importance for poultry egg production.
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Affiliation(s)
- Karolina Frydrych
- Department of Animal Physiology and Endocrinology, University of Agriculture in Krakow, al. Mickiewicza 24/28, 30-059, Krakow, Poland
| | - Dominika Wolak
- Department of Animal Physiology and Endocrinology, University of Agriculture in Krakow, al. Mickiewicza 24/28, 30-059, Krakow, Poland
| | - Anna Hrabia
- Department of Animal Physiology and Endocrinology, University of Agriculture in Krakow, al. Mickiewicza 24/28, 30-059, Krakow, Poland.
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3
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Hua R, Truong VA, Fajardo RJ, Guda T, Gu S, Jiang JX. Connexin hemichannels drive lactation-induced osteocyte acidification and perilacunar-canalicular remodeling. Cell Rep 2024; 43:114363. [PMID: 38935505 DOI: 10.1016/j.celrep.2024.114363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 04/30/2024] [Accepted: 05/31/2024] [Indexed: 06/29/2024] Open
Abstract
The maternal skeleton experiences significant bone loss during lactation, followed by rapid restoration post weaning. Parathyroid-related protein (PTHrP)-induced acidification of the perilacunar matrix by osteocytes is crucial in this process, yet its mechanism remains unclear. Here, we identify Cx43 hemichannels (HCs) as key mediators of osteocyte acidification and perilacunar-canalicular remodeling (PLR). Utilizing transgenic mouse models expressing dominant-negative Cx43 mutants, we show that mice with impaired Cx43 HCs exhibit attenuated lactation-induced responses compared to wild-type and only gap junction-impaired groups, including lacunar enlargement, upregulation of PLR genes, and bone loss with compromised mechanical properties. Furthermore, inhibition of HCs by a Cx43 antibody blunts PTHrP-induced calcium influx and protein kinase A activation, followed by impaired osteocyte acidification. Additionally, impeded HCs suppress bone recovery during the post-lactation period. Our findings highlight the pivotal role of Cx43 HCs in orchestrating dynamic bone changes during lactation and recovery by regulating acidification and remodeling enzyme expression.
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Affiliation(s)
- Rui Hua
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Vu A Truong
- School of Osteopathic Medicine, University of the Incarnate Word, San Antonio, TX 78209, USA
| | - Roberto J Fajardo
- School of Osteopathic Medicine, University of the Incarnate Word, San Antonio, TX 78209, USA
| | - Teja Guda
- Department of Biomedical Engineering and Chemical Engineering, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
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4
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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 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] [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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5
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Matarrese P, Signore M, Ascione B, Fanelli G, Paggi MG, Abbruzzese C. Chlorpromazine overcomes temozolomide resistance in glioblastoma by inhibiting Cx43 and essential DNA repair pathways. J Transl Med 2024; 22:667. [PMID: 39026284 PMCID: PMC11256652 DOI: 10.1186/s12967-024-05501-3] [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: 05/06/2024] [Accepted: 07/10/2024] [Indexed: 07/20/2024] Open
Abstract
BACKGROUND In the fight against GBM, drug repurposing emerges as a viable and time-saving approach to explore new treatment options. Chlorpromazine, an old antipsychotic medication, has recently arisen as a promising candidate for repositioning in GBM therapy in addition to temozolomide, the first-line standard of care. We previously demonstrated the antitumor efficacy of chlorpromazine and its synergistic effects with temozolomide in suppressing GBM cell malignant features in vitro. This prompted us to accomplish a Phase II clinical trial to evaluate the efficacy and safety of adding chlorpromazine to temozolomide in GBM patients with unmethylated MGMT gene promoter. In this in vitro study, we investigate the potential role of chlorpromazine in overcoming temozolomide resistance. METHODS In our experimental set, we analyzed Connexin-43 expression at both the transcriptional and protein levels in control- and chlorpromazine-treated GBM cells. DNA damage and subsequent repair were assessed by immunofluorescence of γ-H2AX and Reverse-Phase Protein microArrays in chlorpromazine treated GBM cell lines. To elucidate the relationship between DNA repair systems and chemoresistance, we analyzed a signature of DNA repair genes in GBM cells after treatment with chlorpromazine, temozolomide and Connexin-43 downregulation. RESULTS Chlorpromazine treatment significantly downregulated connexin-43 expression in GBM cells, consequently compromising connexin-dependent cellular resilience, and ultimately contributing to cell death. In line with this, we observed concordant post-translational modifications of molecular determinants involved in DNA damage and repair pathways. Our evaluation of DNA repair genes revealed that temozolomide elicited an increase, while chlorpromazine, as well as connexin-43 silencing, a decrease in DNA repair gene expression in GBM cells. CONCLUSIONS Chlorpromazine potentiates the cytotoxic effects of the alkylating agent temozolomide through a mechanism involving downregulation of Cx43 expression and disruption of the cell cycle arrest essential for DNA repair processes. This finding suggests that chlorpromazine may be a potential therapeutic strategy to overcome TMZ resistance in GBM cells by inhibiting their DNA repair mechanisms.
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Affiliation(s)
- Paola Matarrese
- Center for Gender-Specific Medicine, Istituto Superiore di Sanità, 00161, Rome, Italy
| | - Michele Signore
- RPPA Unit, Proteomics Area, Core Facilities, Istituto Superiore di Sanità, 00161, Rome, Italy
| | - Barbara Ascione
- Center for Gender-Specific Medicine, Istituto Superiore di Sanità, 00161, Rome, Italy
| | - Giulia Fanelli
- Cellular Networks and Molecular Therapeutic Targets, Proteomics Unit, IRCCS-Regina Elena National Cancer Institute, Via Elio Chianesi 53, 00144, Rome, Italy
| | - Marco G Paggi
- Cellular Networks and Molecular Therapeutic Targets, Proteomics Unit, IRCCS-Regina Elena National Cancer Institute, Via Elio Chianesi 53, 00144, Rome, Italy.
| | - Claudia Abbruzzese
- Cellular Networks and Molecular Therapeutic Targets, Proteomics Unit, IRCCS-Regina Elena National Cancer Institute, Via Elio Chianesi 53, 00144, Rome, Italy.
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6
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Babaeenezhad E, Abdolvahabi Z, Asgharzadeh S, Abdollahi M, Shakeri S, Moradi Sarabi M, Yarahmadi S. Potential function of microRNA miRNA-206 in breast cancer pathogenesis: Mechanistic aspects and clinical implications. Pathol Res Pract 2024; 260:155454. [PMID: 39002434 DOI: 10.1016/j.prp.2024.155454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 07/01/2024] [Accepted: 07/05/2024] [Indexed: 07/15/2024]
Abstract
Breast cancer (BC) is a major public health problem that affects women worldwide. Growing evidence has highlighted the role of miRNA-206 in BC pathogenesis. Changes in its expression have diagnostic and prognostic potential as they are associated with clinicopathological parameters, including lymph node metastasis, overall survival, tumor size, metastatic stage, resistance to chemotherapy, and recurrence. In the present study, we summarized, assessed, and discussed the most recent understanding of the functions of miRNA-206 in BC. Unexpectedly, miRNA-206 was found to control both oncogenic and tumor-suppressive pathways. We also considered corresponding downstream effects and upstream regulators. Finally, we addressed the diagnostic and prognostic value of miRNA-206 and its potential for the development of new therapeutic strategies.
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Affiliation(s)
- Esmaeel Babaeenezhad
- Nutritional Health Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran; Department of Biochemistry and Genetics, School of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Zohreh Abdolvahabi
- Cellular and Molecular Research Centre, Research Institute for Prevention of Non-Communicable Diseases, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Sahar Asgharzadeh
- Cellular and Molecular Research Centre, Research Institute for Prevention of Non-Communicable Diseases, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Masume Abdollahi
- Cellular and Molecular Research Centre, Research Institute for Prevention of Non-Communicable Diseases, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Sara Shakeri
- Cellular and Molecular Research Centre, Research Institute for Prevention of Non-Communicable Diseases, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Mostafa Moradi Sarabi
- Hepatities Research Center, Department of Biochemistry and Genetics, School of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Sahar Yarahmadi
- Nutritional Health Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran.
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Talaverón R, Morado-Díaz CJ, Herrera A, Gálvez V, Pastor AM, Matarredona ER. The Gap Junction Inhibitor Octanol Decreases Proliferation and Increases Glial Differentiation of Postnatal Neural Progenitor Cells. Int J Mol Sci 2024; 25:6288. [PMID: 38927995 PMCID: PMC11203596 DOI: 10.3390/ijms25126288] [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: 03/30/2024] [Revised: 05/30/2024] [Accepted: 06/04/2024] [Indexed: 06/28/2024] Open
Abstract
Neural precursor cells (NPCs) that persist in the postnatal/adult subventricular zone (SVZ) express connexins that form hemichannels and gap junctions. Gap junctional communication plays a role in NPC proliferation and differentiation during development, but its relevance on postnatal age remains to be elucidated. In this work we aimed to evaluate the effect of the blockade of gap junctional communication on proliferation and cell fate of NPCs obtained from the SVZ of postnatal rats. NPCs were isolated and expanded in culture as neurospheres. Electron microscopy revealed the existence of gap junctions among neurosphere cells. Treatment of cultures with octanol, a broad-spectrum gap junction blocker, or with Gap27, a specific blocker for gap junctions formed by connexin43, produced a significant decrease in bromodeoxyuridine incorporation. Octanol treatment also exerted a dose-dependent antiproliferative effect on glioblastoma cells. To analyze possible actions on NPC fate, cells were seeded in the absence of mitogens. Treatment with octanol led to an increase in the percentage of astrocytes and oligodendrocyte precursors, whereas the percentage of neurons remained unchanged. Gap27 treatment, in contrast, did not modify the differentiation pattern of SVZ NPCs. Our results indicate that general blockade of gap junctions with octanol induces significant effects on the behavior of postnatal SVZ NPCs, by reducing proliferation and promoting glial differentiation.
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Affiliation(s)
- Rocío Talaverón
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Sevilla, 41012 Seville, Spain;
- Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain; (C.J.M.-D.); (A.M.P.)
| | - Camilo J. Morado-Díaz
- Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain; (C.J.M.-D.); (A.M.P.)
| | - Alejandro Herrera
- Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain; (C.J.M.-D.); (A.M.P.)
| | - Victoria Gálvez
- Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain; (C.J.M.-D.); (A.M.P.)
| | - Angel M. Pastor
- Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain; (C.J.M.-D.); (A.M.P.)
| | - Esperanza R. Matarredona
- Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain; (C.J.M.-D.); (A.M.P.)
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8
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Su Y, Lucas R, Fulton DJ, Verin AD. Mechanisms of pulmonary endothelial barrier dysfunction in acute lung injury and acute respiratory distress syndrome. CHINESE MEDICAL JOURNAL PULMONARY AND CRITICAL CARE MEDICINE 2024; 2:80-87. [PMID: 39006829 PMCID: PMC11242916 DOI: 10.1016/j.pccm.2024.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
Endothelial cells (ECs) form a semi-permeable barrier between the interior space of blood vessels and the underlying tissues. Pulmonary endothelial barrier integrity is maintained through coordinated cellular processes involving receptors, signaling molecules, junctional complexes, and protein-regulated cytoskeletal reorganization. In acute lung injury (ALI) or its more severe form acute respiratory distress syndrome (ARDS), the loss of endothelial barrier integrity secondary to endothelial dysfunction caused by severe pulmonary inflammation and/or infection leads to pulmonary edema and hypoxemia. Pro-inflammatory agonists such as histamine, thrombin, bradykinin, interleukin 1β, tumor necrosis factor α, vascular endothelial growth factor, angiopoietin-2, and platelet-activating factor, as well as bacterial toxins and reactive oxygen species, cause dynamic changes in cytoskeletal structure, adherens junction disorganization, and detachment of vascular endothelial cadherin (VE-cadherin) from the actin cytoskeleton, leading to an increase in endothelial permeability. Endothelial interactions with leukocytes, platelets, and coagulation enhance the inflammatory response. Moreover, inflammatory infiltration and the associated generation of pro-inflammatory cytokines during infection cause EC death, resulting in further compromise of the structural integrity of lung endothelial barrier. Despite the use of potent antibiotics and aggressive intensive care support, the mortality of ALI is still high, because the mechanisms of pulmonary EC barrier disruption are not fully understood. In this review, we summarized recent advances in the studies of endothelial cytoskeletal reorganization, inter-endothelial junctions, endothelial inflammation, EC death, and endothelial repair in ALI and ARDS, intending to shed some light on the potential diagnostic and therapeutic targets in the clinical management of the disease.
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Affiliation(s)
- Yunchao Su
- Department of Pharmacology & Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Research Service, Charlie Norwood Veterans Affairs Medical Center, Augusta, GA 30912, USA
| | - Rudolf Lucas
- Department of Pharmacology & Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - David J.R. Fulton
- Department of Pharmacology & Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Alexander D. Verin
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
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9
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Okolo CA, Maran JJ, Watts A, Maripillan J, Harkiolaki M, Martínez AD, Green CR, Mugisho OO. Correlative light and X-ray tomography jointly unveil the critical role of connexin43 channels on inflammation-induced cellular ultrastructural alterations. Heliyon 2024; 10:e27888. [PMID: 38560181 PMCID: PMC10979075 DOI: 10.1016/j.heliyon.2024.e27888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 03/06/2024] [Accepted: 03/07/2024] [Indexed: 04/04/2024] Open
Abstract
Non-junctional connexin43 (Cx43) plasma membrane hemichannels have been implicated in several inflammatory diseases, particularly playing a role in ATP release that triggers activation of the inflammasome. Therapies targeting the blocking of the hemichannels to prevent the pathological release or uptake of ions and signalling molecules through its pores are of therapeutic interest. To date, there is no close-to-native, high-definition documentation of the impact of Cx43 hemichannel-mediated inflammation on cellular ultrastructure, neither is there a robust account of the ultrastructural changes that occur following treatment with selective Cx43 hemichannel blockers such as Xentry-Gap19 (XG19). A combination of same-sample correlative high-resolution three-dimensional fluorescence microscopy and soft X-ray tomography at cryogenic temperatures, enabled in the identification of novel 3D molecular interactions within the cellular milieu when comparing behaviour in healthy states and during the early onset or late stages under inflammatory conditions. Notably, our findings suggest that XG19 blockage of connexin hemichannels under pro-inflammatory conditions may be crucial in preventing the direct degradation of connexosomes by lysosomes, without affecting connexin protein translation and trafficking. We also delineated fine and gross cellular phenotypes, characteristic of inflammatory insult or road-to-recovery from inflammation, where XG19 could indirectly prevent and reverse inflammatory cytokine-induced mitochondrial swelling and cellular hypertrophy through its action on Cx43 hemichannels. Our findings suggest that XG19 might have prophylactic and therapeutic effects on the inflammatory response, in line with functional studies.
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Affiliation(s)
- Chidinma Adanna Okolo
- Beamline B24, Life Sciences Division, Diamond Light Source, Didcot, Oxfordshire, United Kingdom
| | - Jack Jonathan Maran
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Amy Watts
- Beamline B24, Life Sciences Division, Diamond Light Source, Didcot, Oxfordshire, United Kingdom
| | - Jaime Maripillan
- Centro Interdisciplinario de Neurociencias de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile
| | - Maria Harkiolaki
- Beamline B24, Life Sciences Division, Diamond Light Source, Didcot, Oxfordshire, United Kingdom
| | - Agustín D. Martínez
- Centro Interdisciplinario de Neurociencias de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile
| | - Colin R. Green
- Department of Ophthalmology, University of Auckland, New Zealand
| | - Odunayo Omolola Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand
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10
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Bellido T. Bisphosphonates for osteoporosis: from bench to clinic. J Clin Invest 2024; 134:e179942. [PMID: 38488010 PMCID: PMC10940084 DOI: 10.1172/jci179942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2024] Open
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11
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Nardin C, Mammano F. Measurement of Ca 2+ Uptake Through Connexin Hemichannels. Methods Mol Biol 2024; 2801:97-109. [PMID: 38578416 DOI: 10.1007/978-1-0716-3842-2_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
Increasing evidence points to deregulated flux of ionized calcium (Ca2+) mediated by hyperactive mutant connexin (Cx) hemichannels (HCs) as a common gain-of-function etiopathogenetic mechanism for several diseases, ranging from skin disorders to nervous system defects. Furthermore, the opening of nonmutated Cx HCs is associated with an impressive list of widespread diseases including, but not limited to, ischemia/stroke, Alzheimer's disease, and epilepsy. HC inhibitors are attracting a growing attention due to their therapeutic potential for numerous pathologies. This chapter describes a quantitative method to measure Ca2+ uptake though HCs expressed in cultured cells. The assay we developed can be used to probe HC activity as wells as to test HC inhibitors. Furthermore, with minor changes it can be easily adapted to high-throughput high-content platforms and/or primary cells and microtissues.
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Affiliation(s)
- Chiara Nardin
- Institute of Biochemistry and Cell Biology, Italian National Research Council, Rome, Italy
- , Genoa, Italy
| | - Fabio Mammano
- Institute of Biochemistry and Cell Biology, Italian National Research Council, Rome, Italy.
- Department of Physics and Astronomy "G. Galilei", University of Padova, Padova, Italy.
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Acosta FM, Riquelme MA, Gu S, Jiang JX. Evaluation of Connexin Hemichannel Activity In Vivo. Methods Mol Biol 2024; 2801:111-124. [PMID: 38578417 DOI: 10.1007/978-1-0716-3842-2_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
Connexin hemichannels (Cx HCs) are hexameric structures at the cell plasma membrane, whose function as membrane transport proteins allows for the passive flow of small hydrophilic molecules and ions (≤1 kDa) between the cytosol and the extracellular environment. Activation of Cx HCs is highly dependent on pathological conditions. HC activity provokes changes in the microenvironment, inducing the dissemination of signaling molecules in both an autocrine and paracrine manner. Given the elicitation of a variety of signaling pathways, and assortment of Cx species and dispersion throughout the body, Cx HCs have been implicated in a range of processes such as cell proliferation, differentiation, cell death, and tissue modeling and remodeling. While studying the expression and localization of Cx HCs can be done using traditional laboratory techniques, such as immunoblot analysis, measuring the functionality/activity of the HCs requires a more explicit methodology and is essential for determining Cx-mediated physiological changes. The study of Cx HC function/activity has focused mainly on in vitro measurements through electrophysiological characterization or, more commonly, using HC-permeable dye uptake studies. Here, we describe the use of dye uptake to measure Cx HC activity in vivo using mechanically stimulated osteocytic Cx43 HCs with Evans blue dye as our model.
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Affiliation(s)
- Francisca M Acosta
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
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13
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Li Y, Acosta FM, Jiang JX. Gap Junctions or Hemichannel-Dependent and Independent Roles of Connexins in Fibrosis, Epithelial-Mesenchymal Transitions, and Wound Healing. Biomolecules 2023; 13:1796. [PMID: 38136665 PMCID: PMC10742173 DOI: 10.3390/biom13121796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/09/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
Fibrosis initially appears as a normal response to damage, where activated fibroblasts produce large amounts of the extracellular matrix (ECM) during the wound healing process to assist in the repair of injured tissue. However, the excessive accumulation of the ECM, unresolved by remodeling mechanisms, leads to organ dysfunction. Connexins, a family of transmembrane channel proteins, are widely recognized for their major roles in fibrosis, the epithelial-mesenchymal transition (EMT), and wound healing. Efforts have been made in recent years to identify novel mediators and targets for this regulation. Connexins form gap junctions and hemichannels, mediating communications between neighboring cells and inside and outside of cells, respectively. Recent evidence suggests that connexins, beyond forming channels, possess channel-independent functions in fibrosis, the EMT, and wound healing. One crucial channel-independent function is their role as the primary functional component for cell adhesion. Other channel-independent functions of connexins involve their roles in mitochondria and exosomes. This review summarizes the latest advances in the channel-dependent and independent roles of connexins in fibrosis, the EMT, and wound healing, with a particular focus on eye diseases, emphasizing their potential as novel, promising therapeutic targets.
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Affiliation(s)
- Yuting Li
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; (Y.L.); (F.M.A.)
- Department of Pathology, Basic Medical School, Ningxia Medical University, Yinchuan 750004, China
| | - Francisca M. Acosta
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; (Y.L.); (F.M.A.)
| | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; (Y.L.); (F.M.A.)
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14
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Ribelayga CP, O’Brien J. When microscopy and electrophysiology meet connectomics-Steve Massey's contribution to unraveling the structure and function of the rod/cone gap junction. FRONTIERS IN OPHTHALMOLOGY 2023; 3:1305131. [PMID: 38983007 PMCID: PMC11182179 DOI: 10.3389/fopht.2023.1305131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 10/31/2023] [Indexed: 07/11/2024]
Abstract
Electrical synapses, formed of gap junctions, are ubiquitous components of the central nervous system (CNS) that shape neuronal circuit connectivity and dynamics. In the retina, electrical synapses can create a circuit, control the signal-to-noise ratio in individual neurons, and support the coordinated neuronal firing of ganglion cells, hence, regulating signal processing at the network, single-cell, and dendritic level. We, the authors, and Steve Massey have had a long interest in gap junctions in retinal circuits, in general, and in the network of photoreceptors, in particular. Our combined efforts, based on a wide array of techniques of molecular biology, microscopy, and electrophysiology, have provided fundamental insights into the molecular structure and properties of the rod/cone gap junction. Yet, a full understanding of how rod/cone coupling controls circuit dynamics necessitates knowing its operating range. It is well established that rod/cone coupling can be greatly reduced or eliminated by bright-light adaptation or pharmacological treatment; however, the upper end of its dynamic range has long remained elusive. This held true until Steve Massey's recent interest for connectomics led to the development of a new strategy to assess this issue. The effort proved effective in establishing, with precision, the connectivity rules between rods and cones and estimating the theoretical upper limit of rod/cone electrical coupling. Comparing electrophysiological measurements and morphological data indicates that under pharmacological manipulation, rod/cone coupling can reach the theoretical maximum of its operating range, implying that, under these conditions, all the gap junction channels present at the junctions are open. As such, channel open probability is likely the main determinant of rod/cone coupling that can change momentarily in a time-of-day- and light-dependent manner. In this article we briefly review our current knowledge of the molecular structure of the rod/cone gap junction and of the mechanisms behind its modulation, and we highlight the recent work led by Steve Massey. Steve's contribution has been critical toward asserting the modulation depth of rod/cone coupling as well as elevating the rod/cone gap junction as one of the most suitable models to examine the role of electrical synapses and their plasticity in neural processing.
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Affiliation(s)
- Christophe P. Ribelayga
- Department of Vision Sciences, University of Houston College of Optometry, Houston, TX, United States
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15
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Mori R, Mae M, Yamanaka H, Kato S, Masuyama R. Locomotor function of skeletal muscle is regulated by vitamin D via adenosine triphosphate metabolism. Nutrition 2023; 115:112117. [PMID: 37531790 DOI: 10.1016/j.nut.2023.112117] [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: 03/16/2023] [Revised: 05/25/2023] [Accepted: 06/01/2023] [Indexed: 08/04/2023]
Abstract
OBJECTIVES During musculoskeletal development, the vitamin D endocrine system is crucial, because vitamin D-dependent calcium absorption is a major regulator of bone growth. Because exercise regimens depend on bone mass, the direct action of active vitamin D (1,25-dihydroxyvitamin D3 [1,25(OH)2D3]) on musculoskeletal performance should be determined. METHODS To evaluate the effect of 1,25(OH)2D3 on muscle tissue, the vitamin D receptor (Vdr) gene was genetically inactivated in mouse skeletal muscle and the role of 1,25(OH)2D3-VDR signaling on locomotor function was assessed. The direct action of 1,25(OH)2D3 on muscle development was determined using cultured C2C12 cells with myogenic differentiation. RESULTS The lack of Vdr activity in skeletal muscle decreased spontaneous locomotor activity, suggesting that the skeletal muscle performance depended on 1,25(OH)2D3-VDR signaling. Bone phenotypes, reduced femoral bone mineral density, and accelerated osteoclast bone resorption were confirmed in mice lacking skeletal muscle Vdr activity. In vitro study revealed that the treatment with 1,25(OH)2D3 decreased the cellular adenosine triphosphate (ATP)-to-adenosine monophosphate ratio without reducing ATP production. Remarkably, protein expressions of connexin 43, an ATP releaser to extracellular space, and ATP metabolizing enzyme ectonucleotide pyrophosphatase phosphodiesterase 1 were increased responding to 1,25(OH)2D3 treatment. Furthermore, the concentration of pyrophosphate in the culture medium, which inhibits tissue calcification, was increased with 1,25(OH)2D3 treatment. In the presence of 1,25(OH)2D3-VDR signaling, calcium accumulation was suppressed in both muscle samples isolated from mice and in cultured C2C12 cells. CONCLUSIONS This study dissected the physiological functions of 1,25(OH)2D3-VDR signaling in muscle and revealed that regulation of ATP dynamics is involved in sustaining locomotor function.
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Affiliation(s)
- Risako Mori
- Graduate School of Gastronomy Management, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Megumi Mae
- Department of Periodontology and Endodontology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Hitoki Yamanaka
- Division of Animal Research, Research Center for Advanced Science and Technology, Shinshu University, Matsumoto, Nagano, Japan
| | - Shigeaki Kato
- Health Sciences Research Center, Iryo Sosei University, Iwaki, Fukushima, Japan; Research Institute of Innovative Medicine, Tokiwa Foundation, Iwaki, Fukushima, Japan
| | - Ritsuko Masuyama
- Graduate School of Gastronomy Management, Ritsumeikan University, Kusatsu, Shiga, Japan.
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16
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Plotkin LI, Asad I, Kritikos AE, Sanz N. Role of Cx43 on the Bone Cell Generation, Function, and Survival. Bioelectricity 2023; 5:188-195. [PMID: 37746312 PMCID: PMC10517329 DOI: 10.1089/bioe.2023.0028] [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
The presence of gap junction intercellular communication structures in bone cells has been known since the early 1970s, further confirmed by Doty and Marotti at the structural level in the 1980-1990s. Work by Civitelli, Donahue, and others showed the expression of Cx43 at the mRNA and protein levels in all bone cell types: osteoclasts (bone resorbing cells), osteoblasts (bone forming cells), and osteocytes (mature osteoblasts embedded in the bone matrix that regulate the function of both osteoclasts and osteoblasts). While Cx45, Cx46, and Cx37 were also shown to be expressed in bone cells, most studies have focused on Cx43, the most abundant member of the connexin (Cx) family of proteins expressed in bone. The role of Cx43 has been shown to be related to the formation of gap junction intercellular channels, to unopposed hemichannels, and to channel independent functions of the molecule. Cx43 participates in the response of bone cells to pharmacological, hormonal, and mechanical stimuli, and it is involved in the skeletal phenotype with old age. Human and murine studies have shown that mutations of Cx43 lead to oculodentodigital dysplasia and craniometaphyseal dysplasia, both conditions associated with abnormalities in the skeleton. However, whereas substantial advances have been made on the skeletal role of Cx43, further research is needed to understand the basis for the effects of mutated Cx43 and potential ways to prevent the effects of these mutations on bone.
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Affiliation(s)
- Lilian I. Plotkin
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Roudebush Veterans Administration Medical Center, Indianapolis, Indiana, USA
- Indiana Center for Musculoskeletal Health, Indianapolis, Indiana, USA
| | - Iqra Asad
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Alex E. Kritikos
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Natasha Sanz
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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17
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Cao X, Cai L, Guo D, Zhang D, Zhou X, Xie J. Fibroblast growth factor 8 facilitates cell-cell communication in chondrocytes via p38-MAPK signaling. Tissue Cell 2023; 83:102155. [PMID: 37451010 DOI: 10.1016/j.tice.2023.102155] [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: 02/28/2023] [Revised: 06/10/2023] [Accepted: 07/03/2023] [Indexed: 07/18/2023]
Abstract
Gap junction intercellular communication (GJIC) is essential for regulating the development of the organism and sustaining the internal environmental homeostasis of multi-cellular tissue. Fibroblast growth factor 8 (FGF8), an indispensable regulator of the skeletal system, is implicated in regulating chondrocyte growth, differentiation, and disease occurrence. However, the influence of FGF8 on GJIC in chondrocytes is not yet known. The study aims to investigate the role of FGF8 on cell-cell communication in chondrocytes and its underlying biomechanism. We found that FGF8 facilitated cell-cell communication in living chondrocytes by the up-regulation of connexin43 (Cx43), the major fundamental component unit of gap junction channels in chondrocytes. FGF8 activated p38-MAPK signaling to increase the expression of Cx43 and promote the cell-cell communication. Inhibition of p38-MAPK signaling impaired the increase of Cx43 expression and cell-cell communication induced by FGF8, indicating the importance of p38-MAPK signaling. These results help to understand the role of FGF8 on cell communication and provide a potential cue for the treatment of cartilage diseases.
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Affiliation(s)
- Xiaoling Cao
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Lang Cai
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Daimo Guo
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Demao Zhang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China; National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China; Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China.
| | - Jing Xie
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China; National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China.
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Wang X, Dong YT, Hu XM, Zhang JZ, Shi NR, Zuo YQ, Wang X. The circadian regulation of extracellular ATP. Purinergic Signal 2023; 19:283-295. [PMID: 35939197 PMCID: PMC9984637 DOI: 10.1007/s11302-022-09881-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 06/24/2022] [Indexed: 11/25/2022] Open
Abstract
Extracellular ATP is a potent signaling molecule released from various cells throughout the body and is intimately involved in the pathophysiological functions of the nervous system and immune system by activating P2 purinergic receptors. Recent increasingly studies showed that extracellular ATP exhibits circadian oscillation with an approximately 24-h periodicity, which participates in regulatory pathways of central oscillator suprachiasmatic nucleus and peripheral oscillator bladder, respectively. Oscillators modulate the protein expression of ATP release channels and ectonucleotidase activity through clock genes; indeed, real-time alterations of ATP release and degradation determine outcomes of temporal character on extracellular ATP rhythm. The regulatory pathways on extracellular ATP rhythm are different in central and peripheral systems. In this review, we summarize the circadian rhythm of extracellular ATP and discuss several circadian regulatory pathways in different organs via ATP release and degradation, to provide a new understanding for purinergic signaling in the regulatory mechanism of circadian rhythm and a potential target to research the circadian regulation of extracellular ATP in other circadian oscillators.
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Affiliation(s)
- Xin Wang
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, 37 Shi-er Qiao Road, Chengdu, 610075 China
| | - Yu-Ting Dong
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, 37 Shi-er Qiao Road, Chengdu, 610075 China
| | - Xiu-Ming Hu
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, 37 Shi-er Qiao Road, Chengdu, 610075 China
| | - Ji-Zhou Zhang
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, 37 Shi-er Qiao Road, Chengdu, 610075 China
| | - Nan-Rui Shi
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, 37 Shi-er Qiao Road, Chengdu, 610075 China
| | - Yan-Qin Zuo
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, 37 Shi-er Qiao Road, Chengdu, 610075 China
| | - Xu Wang
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, 37 Shi-er Qiao Road, Chengdu, 610075 China
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Sihorwala AZ, Lin AJ, Stachowiak JC, Belardi B. Light-Activated Assembly of Connexon Nanopores in Synthetic Cells. J Am Chem Soc 2023; 145:3561-3568. [PMID: 36724060 PMCID: PMC10188233 DOI: 10.1021/jacs.2c12491] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
During developmental processes and wound healing, activation of living cells occurs with spatiotemporal precision and leads to rapid release of soluble molecular signals, allowing communication and coordination between neighbors. Nonliving systems capable of similar responsive release hold great promise for information transfer in materials and site-specific drug delivery. One nonliving system that offers a tunable platform for programming release is synthetic cells. Encased in a lipid bilayer structure, synthetic cells can be outfitted with molecular conduits that span the bilayer and lead to material exchange. While previous work expressing membrane pore proteins in synthetic cells demonstrated content exchange, user-defined control over release has remained elusive. In mammalian cells, connexon nanopore structures drive content release and have garnered significant interest since they can direct material exchange through intercellular contacts. Here, we focus on connexon nanopores and present activated release of material from synthetic cells in a light-sensitive fashion. To do this, we re-engineer connexon nanopores to assemble after post-translational processing by a protease. By encapsulating proteases in light-sensitive liposomes, we show that assembly of nanopores can be triggered by illumination, resulting in rapid release of molecules encapsulated within synthetic cells. Controlling connexon nanopore activity provides an opportunity for initiating communication with extracellular signals and for transferring molecular agents to the cytoplasm of living cells in a rapid, light-guided manner.
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Affiliation(s)
- Ahmed Z Sihorwala
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - Alexander J Lin
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Jeanne C Stachowiak
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - Brian Belardi
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
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20
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Understanding the Role of ATP Release through Connexins Hemichannels during Neurulation. Int J Mol Sci 2023; 24:ijms24032159. [PMID: 36768481 PMCID: PMC9916920 DOI: 10.3390/ijms24032159] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/30/2022] [Accepted: 01/04/2023] [Indexed: 01/25/2023] Open
Abstract
Neurulation is a crucial process in the formation of the central nervous system (CNS), which begins with the folding and fusion of the neural plate, leading to the generation of the neural tube and subsequent development of the brain and spinal cord. Environmental and genetic factors that interfere with the neurulation process promote neural tube defects (NTDs). Connexins (Cxs) are transmembrane proteins that form gap junctions (GJs) and hemichannels (HCs) in vertebrates, allowing cell-cell (GJ) or paracrine (HCs) communication through the release of ATP, glutamate, and NAD+; regulating processes such as cell migration and synaptic transmission. Changes in the state of phosphorylation and/or the intracellular redox potential activate the opening of HCs in different cell types. Cxs such as Cx43 and Cx32 have been associated with proliferation and migration at different stages of CNS development. Here, using molecular and cellular biology techniques (permeability), we demonstrate the expression and functionality of HCs-Cxs, including Cx46 and Cx32, which are associated with the release of ATP during the neurulation process in Xenopus laevis. Furthermore, applications of FGF2 and/or changes in intracellular redox potentials (DTT), well known HCs-Cxs modulators, transiently regulated the ATP release in our model. Importantly, the blockade of HCs-Cxs by carbenoxolone (CBX) and enoxolone (ENX) reduced ATP release with a concomitant formation of NTDs. We propose two possible and highly conserved binding sites (N and E) in Cx46 that may mediate the pharmacological effect of CBX and ENX on the formation of NTDs. In summary, our results highlight the importance of ATP release mediated by HCs-Cxs during neurulation.
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21
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Adzraku SY, Wang G, Cao C, Bao Y, Wang Y, Smith AO, Du Y, Wang H, Li Y, Xu K, Qiao J, Ju W, Zeng L. Robo4 inhibits gamma radiation-induced permeability of a murine microvascular endothelial cell by regulating the junctions. Cell Mol Biol Lett 2023; 28:2. [PMID: 36647012 PMCID: PMC9843922 DOI: 10.1186/s11658-022-00413-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 12/19/2022] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Hematopoietic stem cell transplantation involves irradiation preconditioning which causes bone marrow endothelial cell dysfunction. While much emphasis is on the reconstitution of hematopoietic stem cells in the bone marrow microenvironment, endothelial cell preservation is indispensable to overcome the preconditioning damages. This study aims to ascertain the role of Roundabout 4 (Robo4) in regulating irradiation-induced damage to the endothelium. METHODS Microvascular endothelial cells were treated with γ-radiation to establish an endothelial cell injury model. Robo4 expression in the endothelial cells was manipulated employing lentiviral-mediated RNAi and gene overexpression technology before irradiation treatment. The permeability of endothelial cells was measured using qPCR, immunocytochemistry, and immunoblotting to analyze the effect on the expression and distribution of junctional molecules, adherens junctions, tight junctions, and gap junctions. Using Transwell endothelial monolayer staining, FITC-Dextran permeability, and gap junction-mediated intercellular communication (GJIC) assays, we determined the changes in endothelial functions after Robo4 gene manipulation and irradiation. Moreover, we measured the proportion of CD31 expression in endothelial cells by flow cytometry. We analyzed variations between two or multiple groups using Student's t-tests and ANOVA. RESULTS Ionizing radiation upregulates Robo4 expression but disrupts endothelial junctional molecules. Robo4 deletion causes further degradation of endothelial junctions hence increasing the permeability of the endothelial cell monolayer. Robo4 knockdown in microvascular endothelial cells increases the degradation and delocalization of ZO-1, PECAM-1, occludin, and claudin-5 molecules after irradiation. Conversely, connexin 43 expression increases after silencing Robo4 in endothelial cells to induce permeability but are readily destroyed when exposed to 10 Gy of gamma radiation. Also, Robo4 knockdown enhances Y731-VE-cadherin phosphorylation leading to the depletion and destabilization of VE-cadherin at the endothelial junctions following irradiation. However, Robo4 overexpression mitigates irradiation-induced degradation of tight junctional proteins and stabilizes claudin-5 and ZO-1 distribution. Finally, the enhanced expression of Robo4 ameliorates the irradiation-induced depletion of VE-cadherin and connexin 43, improves the integrity of microvascular endothelial cell junctions, and decreases permeability. CONCLUSION This study reveals that Robo4 maintains microvascular integrity after radiation preconditioning treatment by regulating endothelial permeability and protecting endothelial functions. Our results also provided a potential mechanism to repair the bone marrow vascular niche after irradiation by modulating Robo4 expression.
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Affiliation(s)
- Seyram Yao Adzraku
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China ,Xuzhou Ruihu Health Management Consulting Co., Ltd, Xuzhou, 221002 China
| | - Guozhang Wang
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China ,Xuzhou Ruihu Health Management Consulting Co., Ltd, Xuzhou, 221002 China
| | - Can Cao
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China ,Xuzhou Ruihu Health Management Consulting Co., Ltd, Xuzhou, 221002 China
| | - Yurong Bao
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China
| | - Yizhou Wang
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China
| | - Alhaji Osman Smith
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China
| | - Yuwei Du
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China
| | - Haiyang Wang
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China
| | - Yue Li
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China
| | - Kailin Xu
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China
| | - Jianlin Qiao
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China
| | - Wen Ju
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China ,Xuzhou Ruihu Health Management Consulting Co., Ltd, Xuzhou, 221002 China
| | - Lingyu Zeng
- grid.417303.20000 0000 9927 0537Blood Diseases Institute, Xuzhou Medical University, Xuzhou, 221002 China ,Key Laboratory of Bone Marrow Stem Cell, Xuzhou, 221002 Jiangsu China ,grid.413389.40000 0004 1758 1622Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221002 China
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22
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Ma Q, Miri Z, Haugen HJ, Moghanian A, Loca D. Significance of mechanical loading in bone fracture healing, bone regeneration, and vascularization. J Tissue Eng 2023; 14:20417314231172573. [PMID: 37251734 PMCID: PMC10214107 DOI: 10.1177/20417314231172573] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 04/13/2023] [Indexed: 05/31/2023] Open
Abstract
In 1892, J.L. Wolff proposed that bone could respond to mechanical and biophysical stimuli as a dynamic organ. This theory presents a unique opportunity for investigations on bone and its potential to aid in tissue repair. Routine activities such as exercise or machinery application can exert mechanical loads on bone. Previous research has demonstrated that mechanical loading can affect the differentiation and development of mesenchymal tissue. However, the extent to which mechanical stimulation can help repair or generate bone tissue and the related mechanisms remain unclear. Four key cell types in bone tissue, including osteoblasts, osteoclasts, bone lining cells, and osteocytes, play critical roles in responding to mechanical stimuli, while other cell lineages such as myocytes, platelets, fibroblasts, endothelial cells, and chondrocytes also exhibit mechanosensitivity. Mechanical loading can regulate the biological functions of bone tissue through the mechanosensor of bone cells intraosseously, making it a potential target for fracture healing and bone regeneration. This review aims to clarify these issues and explain bone remodeling, structure dynamics, and mechano-transduction processes in response to mechanical loading. Loading of different magnitudes, frequencies, and types, such as dynamic versus static loads, are analyzed to determine the effects of mechanical stimulation on bone tissue structure and cellular function. Finally, the importance of vascularization in nutrient supply for bone healing and regeneration was further discussed.
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Affiliation(s)
- Qianli Ma
- Department of Biomaterials, Institute
of Clinical Dentistry, University of Oslo, Norway
- Department of Immunology, School of
Basic Medicine, Fourth Military Medical University, Xi’an, PR China
| | - Zahra Miri
- Department of Materials Engineering,
Isfahan University of Technology, Isfahan, Iran
| | - Håvard Jostein Haugen
- Department of Biomaterials, Institute
of Clinical Dentistry, University of Oslo, Norway
| | - Amirhossein Moghanian
- Department of Materials Engineering,
Imam Khomeini International University, Qazvin, Iran
| | - Dagnjia Loca
- Rudolfs Cimdins Riga Biomaterials
Innovations and Development Centre, Institute of General Chemical Engineering,
Faculty of Materials Science and Applied Chemistry, Riga Technical University, Riga,
Latvia
- Baltic Biomaterials Centre of
Excellence, Headquarters at Riga Technical University, Riga, Latvia
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23
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Aghighi Z, Ghorbani Z, Moghaddam MH, Fathi M, Abdollahifar MA, Soleimani M, Karimzadeh F, Rasoolijazi H, Aliaghaei A. Melittin ameliorates motor function and prevents autophagy-induced cell death and astrogliosis in rat models of cerebellar ataxia induced by 3-acetylpyridine. Neuropeptides 2022; 96:102295. [PMID: 36280441 DOI: 10.1016/j.npep.2022.102295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/10/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022]
Abstract
BACKGROUND Cerebellar ataxia (CA) is a form of ataxia that adversely affects the cerebellum. This study aims to investigate the therapeutic effects of melittin (MEL) on a 3-acetylpyridine-induced (3-AP) cerebellar ataxia (CA) rat model. METHODS Initially, CA rat models were generated by 3-AP administration followed by the subcutaneous injection of MEL. The open-field test was used for the evaluation of locomotion and anxiety. Immunohistochemistry was also conducted for the autophagy markers of LC3 and Beclin1. In the next step, the morphology of the astrocyte, the cell responsible for maintaining homeostasis in the CNS, was evaluated by the Sholl analysis. RESULTS The findings suggested that the administration of MEL in a 3-AP model of ataxia improved locomotion and anxiety (P < 0.001), decreased the expression of LC3 (P < 0.01) and Beclin1 (P < 0.05), increased astrocyte complexity (P < 0.05) and reduced astrocyte cell soma size (P < 0.001). CONCLUSIONS Overall, the findings imply that the MEL attenuates the 3-AP-induced autophagy, causes cell death and improves motor function. As such, it could be used as a therapeutic procedure for CA due to its neuroprotective effects.
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Affiliation(s)
- Zahra Aghighi
- Department of Anatomy, School of Medicine, Iran University of Medical Sciences, Tehran, Iran; Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Zeynab Ghorbani
- Department of Anatomy, School of Medicine, Iran University of Medical Sciences, Tehran, Iran; Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Meysam Hassani Moghaddam
- Department of Anatomical Sciences, Faculty of Medicine, AJA University of Medical Sciences, Tehran, Iran
| | - Mobina Fathi
- Student Research Committee, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad-Amin Abdollahifar
- Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mansoureh Soleimani
- Department of Anatomy, School of Medicine, Iran University of Medical Sciences, Tehran, Iran; Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Fariba Karimzadeh
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Homa Rasoolijazi
- Department of Anatomy, School of Medicine, Iran University of Medical Sciences, Tehran, Iran; Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran.
| | - Abbas Aliaghaei
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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24
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Zhang J, Riquelme MA, Hua R, Acosta FM, Gu S, Jiang JX. Connexin 43 hemichannels regulate mitochondrial ATP generation, mobilization, and mitochondrial homeostasis against oxidative stress. eLife 2022; 11:82206. [DOI: 10.7554/elife.82206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 10/25/2022] [Indexed: 11/09/2022] Open
Abstract
Oxidative stress is a major risk factor that causes osteocyte cell death and bone loss. Prior studies primarily focus on the function of cell surface expressed Cx43 channels. Here, we reported a new role of mitochondrial Cx43 (mtCx43) and hemichannels (HCs) in modulating mitochondria homeostasis and function in bone osteocytes under oxidative stress. In murine long bone osteocyte-Y4 cells, the translocation of Cx43 to mitochondria was increased under H2O2-induced oxidative stress. H2O2 increased the mtCx43 level accompanied by elevated mtCx43 HC activity, determined by dye uptake assay. Cx43 knockdown (KD) by the CRISPR-Cas9 lentivirus system resulted in impairment of mitochondrial function, primarily manifested as decreased ATP production. Cx43 KD had reduced intracellular reactive oxidative species levels and mitochondrial membrane potential. Additionally, live-cell imaging results demonstrated that the proton flux was dependent on mtCx43 HCs because its activity was specifically inhibited by an antibody targeting Cx43 C-terminus. The co-localization and interaction of mtCx43 and ATP synthase subunit F (ATP5J2) were confirmed by Förster resonance energy transfer and a protein pull-down assay. Together, our study suggests that mtCx43 HCs regulate mitochondrial ATP generation by mediating K+, H+, and ATP transfer across the mitochondrial inner membrane and the interaction with mitochondrial ATP synthase, contributing to the maintenance of mitochondrial redox levels in response to oxidative stress.
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Affiliation(s)
- Jingruo Zhang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center
| | - Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center
| | - Rui Hua
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center
| | - Francisca M Acosta
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center
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25
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A Quantitative Assay for Ca2+ Uptake through Normal and Pathological Hemichannels. Int J Mol Sci 2022; 23:ijms23137337. [PMID: 35806342 PMCID: PMC9266989 DOI: 10.3390/ijms23137337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 06/26/2022] [Accepted: 06/28/2022] [Indexed: 12/25/2022] Open
Abstract
Connexin (Cx) hemichannels (HCs) are large pore hexameric structures that allow the exchange of ions, metabolites and a variety of other molecules between the cell cytoplasm and extracellular milieu. HC inhibitors are attracting growing interest as drug candidates because deregulated fluxes through HCs have been implicated in a plethora of genetic conditions and other diseases. HC activity has been mainly investigated by electrophysiological methods and/or using HC-permeable dye uptake measurements. Here, we present an all-optical assay based on fluorometric measurements of ionized calcium (Ca2+) uptake with a Ca2+-selective genetically encoded indicator (GCaMP6s) that permits the optical tracking of cytosolic Ca2+ concentration ([Ca2+]cyt) changes with high sensitivity. We exemplify use of the assay in stable pools of HaCaT cells overexpressing human Cx26, Cx46, or the pathological mutant Cx26G45E, under control of a tetracycline (Tet) responsive element (TRE) promoter (Tet-on). We demonstrate the usefulness of the assay for the characterization of new monoclonal antibodies (mAbs) targeting the extracellular domain of the HCs. Although we developed the assay on a spinning disk confocal fluorescence microscope, the same methodology can be extended seamlessly to high-throughput high-content platforms to screen other kinds of inhibitors and/or to probe HCs expressed in primary cells and microtissues.
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26
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The Role of Connexin in Ophthalmic Neovascularization and the Interaction between Connexin and Proangiogenic Factors. J Ophthalmol 2022; 2022:8105229. [PMID: 35783340 PMCID: PMC9242797 DOI: 10.1155/2022/8105229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 06/11/2022] [Indexed: 12/02/2022] Open
Abstract
The formation of new blood vessels is an important physiological process that occurs during development. When the body is injured, new blood vessel formation helps the body recuperate by supplying more oxygen and nutrients. However, this mechanism can have a negative effect. In ophthalmologic diseases, such as corneal new blood vessels, neonatal vascular glaucoma, and diabetes retinopathy, the formation of new blood vessels has become a critical component in patient survival. Connexin is a protein that regulates the cellular and molecular material carried by cells. It has been demonstrated that it is widely expressed in vascular endothelial cells, where it forms a slit connection between adjacent cells to promote cell-cell communication via hemichannels, as well as substance exchange into intracellular environments. Numerous studies have demonstrated that connexin in vascular endothelial cells plays an important role in angiogenesis and vascular leakage. The purpose of this study was to investigate the effect between the angiogenesis-associated factor and the connexin. It also reveals the effect of connexin on ophthalmic neovascularization.
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27
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Jang MW, Lim J, Park MG, Lee JH, Lee CJ. Active role of glia-like supporting cells in the organ of Corti: Membrane proteins and their roles in hearing. Glia 2022; 70:1799-1825. [PMID: 35713516 DOI: 10.1002/glia.24229] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 05/23/2022] [Accepted: 05/30/2022] [Indexed: 12/13/2022]
Abstract
The organ of Corti, located in the cochlea in the inner ear, is one of the major sensory organs involved in hearing. The organ of Corti consists of hair cells, glia-like supporting cells, and the cochlear nerve, which work in harmony to receive sound from the outer ear and transmit auditory signals to the cochlear nucleus in the auditory ascending pathway. In this process, maintenance of the endocochlear potential, with a high potassium gradient and clearance of electrolytes and biochemicals in the inner ear, is critical for normal sound transduction. There is an emerging need for a thorough understanding of each cell type involved in this process to understand the sophisticated mechanisms of the organ of Corti. Hair cells have long been thought to be active, playing a primary role in the cochlea in actively detecting and transmitting signals. In contrast, supporting cells are thought to be silent and function to support hair cells. However, growing lines of evidence regarding the membrane proteins that mediate ionic movement in supporting cells have demonstrated that supporting cells are not silent, but actively play important roles in normal signal transduction. In this review, we summarize studies that characterize diverse membrane proteins according to the supporting cell subtypes involved in cochlear physiology and hearing. This review contributes to a better understanding of supporting cell functions and facilitates the development of potential therapeutic tools for hearing loss.
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Affiliation(s)
- Minwoo Wendy Jang
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Jiwoon Lim
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea.,IBS School, University of Science and Technology (UST), Daejeon, Republic of Korea
| | - Mingu Gordon Park
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Jae-Hun Lee
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - C Justin Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea.,IBS School, University of Science and Technology (UST), Daejeon, Republic of Korea
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28
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Hrabia A, Wolak D, Kowalik K, Sechman A. Alterations in connexin 43 gene and protein expression in the chicken oviduct following tamoxifen treatment. Theriogenology 2022; 188:125-134. [DOI: 10.1016/j.theriogenology.2022.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 06/01/2022] [Accepted: 06/01/2022] [Indexed: 11/30/2022]
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29
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Omolaoye TS, Jalaleddine N, Cardona Maya WD, du Plessis SS. Mechanisms of SARS-CoV-2 and Male Infertility: Could Connexin and Pannexin Play a Role? Front Physiol 2022; 13:866675. [PMID: 35721552 PMCID: PMC9205395 DOI: 10.3389/fphys.2022.866675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/02/2022] [Indexed: 11/13/2022] Open
Abstract
The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on male infertility has lately received significant attention. SARS-CoV-2, the virus that causes coronavirus disease (COVID-19) in humans, has been shown to impose adverse effects on both the structural components and function of the testis, which potentially impact spermatogenesis. These adverse effects are partially explained by fever, systemic inflammation, oxidative stress, and an increased immune response leading to impaired blood-testis barrier. It has been well established that efficient cellular communication via gap junctions or functional channels is required for tissue homeostasis. Connexins and pannexins are two protein families that mediate autocrine and paracrine signaling between the cells and the extracellular environment. These channel-forming proteins have been shown to play a role in coordinating cellular communication in the testis and epididymis. Despite their role in maintaining a proper male reproductive milieu, their function is disrupted under pathological conditions. The involvement of these channels has been well documented in several physiological and pathological conditions and their designated function in infectious diseases. However, their role in COVID-19 and their meaningful contribution to male infertility remains to be elucidated. Therefore, this review highlights the multivariate pathophysiological mechanisms of SARS-CoV-2 involvement in male reproduction. It also aims to shed light on the role of connexin and pannexin channels in disease progression, emphasizing their unexplored role and regulation of SARS-CoV-2 pathophysiology. Finally, we hypothesize the possible involvement of connexins and pannexins in SARS-CoV-2 inducing male infertility to assist future research ideas targeting therapeutic approaches.
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Affiliation(s)
- Temidayo S. Omolaoye
- Department of Basic Sciences, College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Nour Jalaleddine
- Department of Basic Sciences, College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Walter D. Cardona Maya
- Reproduction Group, Department of Microbiology and Parasitology, Faculty of Medicine, Universidad de Antioquia, Medellin, Colombia
| | - Stefan S. du Plessis
- Department of Basic Sciences, College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
- Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa
- *Correspondence: Stefan S. du Plessis,
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30
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Fadjukov J, Wienbar S, Hakanen S, Aho V, Vihinen-Ranta M, Ihalainen TO, Schwartz GW, Nymark S. Gap junctions and connexin hemichannels both contribute to the electrical properties of retinal pigment epithelium. J Gen Physiol 2022; 154:213064. [PMID: 35275193 PMCID: PMC8922333 DOI: 10.1085/jgp.202112916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 02/17/2022] [Indexed: 12/13/2022] Open
Abstract
Gap junctions are intercellular channels that permit the transfer of ions and small molecules between adjacent cells. These cellular junctions are particularly dense in the retinal pigment epithelium (RPE), and their contribution to many retinal diseases has been recognized. While gap junctions have been implicated in several aspects of RPE physiology, their role in shaping the electrical properties of these cells has not been characterized in mammals. The role of gap junctions in the electrical properties of the RPE is particularly important considering the growing appreciation of RPE as excitable cells containing various voltage-gated channels. We used a whole-cell patch clamp to measure the electrical characteristics and connectivity between RPE cells, both in cultures derived from human embryonic stem cells and in the intact RPE monolayers from mouse eyes. We found that the pharmacological blockade of gap junctions eliminated electrical coupling between RPE cells, and that the blockade of gap junctions or Cx43 hemichannels significantly increased their input resistance. These results demonstrate that gap junctions function in the RPE not only as a means of molecular transport but also as a regulator of electrical excitability.
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Affiliation(s)
- Julia Fadjukov
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Sophia Wienbar
- Department of Ophthalmology, Northwestern University, Chicago, IL.,Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL.,Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL
| | - Satu Hakanen
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Vesa Aho
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Maija Vihinen-Ranta
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Teemu O Ihalainen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Gregory W Schwartz
- Department of Ophthalmology, Northwestern University, Chicago, IL.,Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL.,Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL
| | - Soile Nymark
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
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31
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Mechanical regulation of bone remodeling. Bone Res 2022; 10:16. [PMID: 35181672 PMCID: PMC8857305 DOI: 10.1038/s41413-022-00190-4] [Citation(s) in RCA: 130] [Impact Index Per Article: 65.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 11/04/2021] [Accepted: 12/13/2021] [Indexed: 12/17/2022] Open
Abstract
Bone remodeling is a lifelong process that gives rise to a mature, dynamic bone structure via a balance between bone formation by osteoblasts and resorption by osteoclasts. These opposite processes allow the accommodation of bones to dynamic mechanical forces, altering bone mass in response to changing conditions. Mechanical forces are indispensable for bone homeostasis; skeletal formation, resorption, and adaptation are dependent on mechanical signals, and loss of mechanical stimulation can therefore significantly weaken the bone structure, causing disuse osteoporosis and increasing the risk of fracture. The exact mechanisms by which the body senses and transduces mechanical forces to regulate bone remodeling have long been an active area of study among researchers and clinicians. Such research will lead to a deeper understanding of bone disorders and identify new strategies for skeletal rejuvenation. Here, we will discuss the mechanical properties, mechanosensitive cell populations, and mechanotransducive signaling pathways of the skeletal system.
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32
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Gap Junction-Dependent and -Independent Functions of Connexin43 in Biology. BIOLOGY 2022; 11:biology11020283. [PMID: 35205149 PMCID: PMC8869330 DOI: 10.3390/biology11020283] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/08/2022] [Accepted: 02/10/2022] [Indexed: 12/21/2022]
Abstract
For the first time in animal evolution, the emergence of gap junctions allowed direct exchanges of cellular substances for communication between two cells. Innexin proteins constituted primordial gap junctions until the connexin protein emerged in deuterostomes and took over the gap junction function. After hundreds of millions of years of gene duplication, the connexin gene family now comprises 21 members in the human genome. Notably, GJA1, which encodes the Connexin43 protein, is one of the most widely expressed and commonly studied connexin genes. The loss of Gja1 in mice leads to swelling and a blockage of the right ventricular outflow tract and death of the embryos at birth, suggesting a vital role of Connexin43 gap junction in heart development. Since then, the importance of Connexin43-mediated gap junction function has been constantly expanded to other types of cells. Other than forming gap junctions, Connexin43 can also form hemichannels to release or uptake small molecules from the environment or even mediate many physiological processes in a gap junction-independent manner on plasma membranes. Surprisingly, Connexin43 also localizes to mitochondria in the cell, playing important roles in mitochondrial potassium import and respiration. At the molecular level, Connexin43 mRNA and protein are processed with very distinct mechanisms to yield carboxyl-terminal fragments with different sizes, which have their unique subcellular localization and distinct biological activities. Due to many exciting advancements in Connexin43 research, this review aims to start with a brief introduction of Connexin43 and then focuses on updating our knowledge of its gap junction-independent functions.
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33
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Peng B, Xu C, Wang S, Zhang Y, Li W. The Role of Connexin Hemichannels in Inflammatory Diseases. BIOLOGY 2022; 11:biology11020237. [PMID: 35205103 PMCID: PMC8869213 DOI: 10.3390/biology11020237] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 01/28/2022] [Accepted: 02/01/2022] [Indexed: 02/04/2023]
Abstract
The connexin protein family consists of approximately 20 members, and is well recognized as the structural unit of the gap junction channels that perforate the plasma membranes of coupled cells and, thereby, mediate intercellular communication. Gap junctions are assembled by two preexisting hemichannels on the membranes of apposing cells. Non-junctional connexin hemichannels (CxHC) provide a conduit between the cell interior and the extracellular milieu, and are believed to be in a protectively closed state under physiological conditions. The development and characterization of the peptide mimetics of the amino acid sequences of connexins have resulted in the development of a panel of blockers with a higher selectivity for CxHC, which have become important tools for defining the role of CxHC in various biological processes. It is increasingly clear that CxHC can be induced to open by pathogen-associated molecular patterns. The opening of CxHC facilitates the release of damage-associated molecular patterns, a class of endogenous molecules that are critical for the pathogenesis of inflammatory diseases. The blockade of CxHC leads to attenuated inflammation, reduced tissue injury and improved organ function in human and animal models of about thirty inflammatory diseases and disorders. These findings demonstrate that CxHC may contribute to the intensification of inflammation, and serve as a common target in the treatments of various inflammatory diseases. In this review, we provide an update on the progress in the understanding of CxHC, with a focus on the role of these channels in inflammatory diseases.
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Affiliation(s)
| | | | | | - Yijie Zhang
- Correspondence: (Y.Z.); (W.L.); Tel.: +86-13903782431 (Y.Z.); +86-17839250252 (W.L.)
| | - Wei Li
- Correspondence: (Y.Z.); (W.L.); Tel.: +86-13903782431 (Y.Z.); +86-17839250252 (W.L.)
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34
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Vultaggio-Poma V, Falzoni S, Chiozzi P, Sarti AC, Adinolfi E, Giuliani AL, Sánchez-Melgar A, Boldrini P, Zanoni M, Tesei A, Pinton P, Di Virgilio F. Extracellular ATP is increased by release of ATP-loaded microparticles triggered by nutrient deprivation. Theranostics 2022; 12:859-874. [PMID: 34976217 PMCID: PMC8692914 DOI: 10.7150/thno.66274] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 11/16/2021] [Indexed: 02/06/2023] Open
Abstract
Rationale: Caloric restriction improves the efficacy of anti-cancer therapy. This effect is largely dependent on the increase of the extracellular ATP concentration in the tumor microenvironment (TME). Pathways for ATP release triggered by nutrient deprivation are largely unknown. Methods: The extracellular ATP (eATP) concentration was in vivo measured in the tumor microenvironment of B16F10-inoculated C57Bl/6 mice with the pmeLuc probe. Alternatively, the pmeLuc-TG-mouse was used. Caloric restriction was in vivo induced with hydroxycitrate (HC). B16F10 melanoma cells or CT26 colon carcinoma cells were in vitro exposed to serum starvation to mimic nutrient deprivation. Energy metabolism was monitored by Seahorse. Microparticle release was measured by ultracentrifugation and by Nanosight. Results: Nutrient deprivation increases eATP release despite the dramatic inhibition of intracellular energy synthesis. Under these conditions oxidative phosphorylation was dramatically impaired, mitochondria fragmented and glycolysis and lactic acid release were enhanced. Nutrient deprivation stimulated a P2X7-dependent release of ATP-loaded, mitochondria-containing, microparticles as well as of naked mitochondria. Conclusions: Nutrient deprivation promotes a striking accumulation of eATP paralleled by a large release of ATP-laden microparticles and of naked mitochondria. This is likely to be a main mechanism driving the accumulation of eATP into the TME.
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Fan LX, Tao L, Lai YC, Cai SY, Zhao ZY, Yang F, Su RY, Wang Q. Cx32 promotes autophagy and produces resistance to SN‑induced apoptosis via activation of AMPK signalling in cervical cancer. Int J Oncol 2022; 60:10. [PMID: 34970699 DOI: 10.3892/ijo.2021.5300] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 10/01/2021] [Indexed: 11/06/2022] Open
Abstract
The roles of gap junctions (GJs) and its components, connexins, in the autophagy of cervical cancer cells have been rarely investigated. Our previous study demonstrated that connexin 32 (Cx32) exerted an anti‑apoptotic effect on cervical cancer. However, as an important regulator of apoptosis, whether the autophagy is involved in the function of Cx32 on cervical cancer cells is not well defined. The present study aimed to investigate the role of Cx32 on autophagy and apoptosis inhibition in cervical cancer cells. The expression levels of Cx32 and the autophagy‑associated protein LC3‑Ⅱ in paracancerous cervical tissues (n=30) and cervical cancer (n=50) tissues were determined via western blotting. In total, 45 cervical cancer specimens were used to evaluate the clinical relevance of Cx32 and LC3‑Ⅱ. It was found that both Cx32 and LC3‑Ⅱ were upregulated in cervical cancer tissues compared with those in paracancerous cervical tissues. The effect of Cx32 on autophagy was examined by detecting the change of LC3‑Ⅱ using western blotting, transfection with enhanced green fluorescent protein‑LC3 plasmid and transmission electron microscopy analysis. Overexpression of Cx32 significantly enhanced autophagy in HeLa‑Cx32 cells, whereas knockdown of Cx32 suppressed autophagy in C‑33A cells. The flow cytometry results demonstrated that Cx32 inhibited the apoptosis of cervical cancer cells by promoting autophagy. Moreover, Cx32 triggered autophagy via the activation of the AMP‑activated protein kinase (AMPK) signalling, regardless of the presence or absence of GJs. Collectively, it was identified that Cx32 exerted its anti‑apoptotic effect by activating autophagy via the AMPK pathway in cervical cancer, which demonstrates a novel mechanism for Cx32 in human cervical cancer progression.
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Affiliation(s)
- Li-Xia Fan
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat‑Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Liang Tao
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat‑Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Yong-Chang Lai
- Department of Urology, The Eighth Affiliated Hospital, Sun Yat‑Sen University, Shenzhen, Guangdong 518033, P.R. China
| | - Shao-Yi Cai
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat‑Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Zi-Yu Zhao
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat‑Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Feng Yang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat‑Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Ri-Ya Su
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat‑Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Qin Wang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat‑Sen University, Guangzhou, Guangdong 510080, P.R. China
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Osteocytic Connexin Hemichannels Modulate Oxidative Bone Microenvironment and Breast Cancer Growth. Cancers (Basel) 2021; 13:cancers13246343. [PMID: 34944962 PMCID: PMC8699531 DOI: 10.3390/cancers13246343] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/09/2021] [Accepted: 12/13/2021] [Indexed: 11/16/2022] Open
Abstract
Osteocytes, the most abundant bone cell types embedded in the mineral matrix, express connexin 43 (Cx43) hemichannels that play important roles in bone remodeling and osteocyte survival. Estrogen deficiency decreases osteocytic Cx43 hemichannel activity and causes a loss in osteocytes' resistance to oxidative stress (OS). In this study, we showed that OS reduced the growth of both human (MDA-MB-231) and murine (Py8119) breast cancer cells. However, co-culturing these cells with osteocytes reduced the inhibitory effect of OS on breast cancer cells, and this effect was ablated by the inhibition of Cx43 hemichannels. Py8119 cells were intratibially implanted in the bone marrow of ovariectomized (OVX) mice to determine the role of osteocytic Cx43 hemichannels in breast cancer bone metastasis in response to OS. Two transgenic mice overexpressing dominant-negative Cx43 mutants, R76W and Δ130-136, were adopted for this study; the former inhibits gap junctions while the latter inhibits gap junctions and hemichannels. Under normal conditions, Δ130-136 mice had significantly more tumor growth in bone than that in WT and R76W mice. OVX increased tumor growth in R76W but had no significant effect on WT mice. In contrast, OVX reduced tumor growth in Δ130-136 mice. To confirm the role of OS, WT and Δ130-136 mice were administered the antioxidant N-acetyl cysteine (NAC). NAC increased tumor burden and growth in Δ130-136 mice but not in WT mice. Together, the data suggest that osteocytes and Cx43 hemichannels play pivotal roles in modulating the oxidative microenvironment and breast cancer growth in the bone.
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Wang Q, Duan M, Liao J, Xie J, Zhou C. Are Osteoclasts Mechanosensitive Cells? J Biomed Nanotechnol 2021; 17:1917-1938. [PMID: 34706793 DOI: 10.1166/jbn.2021.3171] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Skeleton metabolism is a process in which osteoclasts constantly remove old bone and osteoblasts form new osteoid and induce mineralization; disruption of this balance may cause diseases. Osteoclasts play a key role in bone metabolism, as osteoclastogenesis marks the beginning of each bone remodeling cycle. As the only cell capable of bone resorption, osteoclasts are derived from the monocyte/macrophage hematopoietic precursors that terminally adhere to mineralized extracellular matrix, and they subsequently break down the extracellular compartment. Bone is generally considered the load-burdening tissue, bone homeostasis is critically affected by mechanical conductions, and the bone cells are mechanosensitive. The functions of various bone cells under mechanical forces such as chondrocytes and osteoblasts have been reported; however, the unique bone-resorbing osteoclasts are less studied. The oversuppression of osteoclasts in mechanical studies may be because of its complicated differentiation progress and flexible structure, which increases difficulty in targeting mechanical structures. This paper will focus on recent findings regarding osteoclasts and attempt to uncover proposed candidate mechanosensing structures in osteoclasts including podosome-associated complexes, gap junctions and transient receptor potential family (ion channels). We will additionally describe possible mechanotransduction signaling pathways including GTPase ras homologue family member A (RhoA), Yes-associated protein/transcriptional co-activator with PDZ-binding motif (TAZ), Ca2+ signaling and non-canonical Wnt signaling. According to numerous studies, evaluating the possible influence of various physical environments on osteoclastogenesis is conducive to the study of bone homeostasis.
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Affiliation(s)
- Qingxuan Wang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610064, China
| | - Mengmeng Duan
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610064, China
| | - Jingfeng Liao
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610064, China
| | - Jing Xie
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610064, China
| | - Chenchen Zhou
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610064, China
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38
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Quan Y, Du Y, Wu C, Gu S, Jiang JX. Connexin hemichannels regulate redox potential via metabolite exchange and protect lens against cellular oxidative damage. Redox Biol 2021; 46:102102. [PMID: 34474393 PMCID: PMC8408634 DOI: 10.1016/j.redox.2021.102102] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 11/23/2022] Open
Abstract
Increased oxidative stress contributes to cataract formation during aging. Anterior epithelial cells are a frontline antioxidant defense system with powerful capacities to maintain redox homeostasis and lens transparency. In this study, we report a new molecular mechanism of connexin (Cx) hemichannels (HCs) in lens epithelial cells to protect lens against oxidative stress. Our results showed haploinsufficiency of Cx43 elevated oxidative stress and susceptibility to cataracts in the mouse lens. Cx43 HCs opened in response to hydrogen peroxide (H2O2) or ultraviolet radiation (UVR) in human lens epithelium HLE-B3 cells, and this activation contributed to a cellular protective mechanism against oxidative stress-induced apoptotic cell death. Furthermore, we found that Cx43 HCs mediated the exchange of oxidants and antioxidants in lens epithelial cells undergoing oxidative stress. These transporting activities facilitated a reduction of intracellular reactive oxygen species (ROS) accumulation and maintained the intracellular glutathione (GSH) level through the exchange of redox metabolites and change of anti-oxidative gene expression. In addition, we show that Cx43 HCs can be regulated by the intracellular redox state and this regulation is mediated by residue Cys260 located at the Cx43 C-terminus. Together, our results demonstrate that Cx43 HCs activated by oxidative stress in the lens epithelial cells play a key role in maintaining redox homeostasis in lens under oxidative stress. Our findings contribute to advancing our understanding of oxidative stress induced lens disorders, such as age-related non-congenital cataracts.
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Affiliation(s)
- Yumeng Quan
- Department of Ophthalmology, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China; Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Yu Du
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Changrui Wu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA.
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Unal YC, Yavuz B, Ozcivici E, Mese G. The role of connexins in breast cancer: from misregulated cell communication to aberrant intracellular signaling. Tissue Barriers 2021; 10:1962698. [PMID: 34355641 DOI: 10.1080/21688370.2021.1962698] [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: 12/24/2022] Open
Abstract
In spite of clinical advancements and improved diagnostic techniques, breast cancers are the leading cause of cancer-associated deaths in women worldwide. Although 70% of early breast cancers can be cured, there are no efficient therapies against metastatic breast cancers. Several factors including connexins and gap junctions play roles in breast tumorigenesis. Connexins are critical for cellular processes as a linkage between connexin mutations and hereditary disorders demonstrated their importance for tissue homeostasis. Further, alterations in their expression, localization and channel activities were observed in many cancers including breast cancer. Both channel-dependent and independent functions of connexins were reported in initiation and progression of cancers. Unlike initial reports suggesting tumor suppressor functions, connexins and gap junctions have stage, context and isoform dependent effects in breast cancers similar to other cancers. In this review, we tried to describe the current understanding of connexins in tumorigenesis specifically in breast cancers.
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Affiliation(s)
- Yagmur Ceren Unal
- Faculty of Science, Department of Molecular Biology and Genetics, Izmir Institute of Technology, Urla, Izmir, Turkey
| | - Busra Yavuz
- Faculty of Science, Department of Molecular Biology and Genetics, Izmir Institute of Technology, Urla, Izmir, Turkey
| | - Engin Ozcivici
- Department of Bioengineering, Faculty of Engineering, Izmir Institute of Technology, Urla, Izmir, Turkey
| | - Gulistan Mese
- Faculty of Science, Department of Molecular Biology and Genetics, Izmir Institute of Technology, Urla, Izmir, Turkey
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40
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Seeing Is Believing: Gap Junctions in Motion. BIOLOGY 2021; 10:biology10060494. [PMID: 34199345 PMCID: PMC8227072 DOI: 10.3390/biology10060494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 06/01/2021] [Indexed: 11/18/2022]
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41
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Chen M, Li G, Zhang L, Ning K, Yang B, Jiang JX, Wang DE, Xu H. Primary Osteocyte Supernatants Metabolomic Profiling of Two Transgenic Mice With Connexin43 Dominant Negative Mutants. Front Endocrinol (Lausanne) 2021; 12:649994. [PMID: 34093433 PMCID: PMC8169970 DOI: 10.3389/fendo.2021.649994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 04/06/2021] [Indexed: 11/13/2022] Open
Abstract
Osteocytes could release some small molecules (≤ 1 kDa) through gap junctions and hemichannels to extracellular environment, such as prostaglandin E2 (PGE2), nitric oxide (NO) and adenosine triphosphate (ATP), which play key roles in transferring signals between bone cells and other tissue cells. Connexin (Cx) 43 is the most abundant connexin in osteocytes. To further discover molecules released by osteocytes through Cx43 channels and better understand the regulatory function of Cx43 channels in osteocytes, we performed non-targeted global metabolomics analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) on conditioned medium collected from osteocytes isolated from two transgenic mouse models with Cx43 dominant negative mutants driven by a 10 kb-DMP1 promoter: R76W (gap junctions are blocked, whereas hemichannels are promoted) and Δ130-136 (both gap junctions and hemichannels are blocked). The results revealed that several new categories of molecules, such as "fatty acyls" and "carboxylic acids and derivatives", could be released through osteocytic Cx43 channels. In addition, alteration of Cx43 channel function affected the release of metabolites related to inflammatory reaction and oxidative stress. Pathway analysis further showed that citric acid cycle was the most differential metabolic pathway regulated by Cx43 channels. In sum, these results isolated new potential metabolites released by osteocytes through Cx43 channels, and offered a novel perspective to understand the regulatory mechanisms of osteocytes on themselves and other cells as well.
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Affiliation(s)
- Meng Chen
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Guobin Li
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Lan Zhang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Kaiting Ning
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Baoqiang Yang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - Dong-En Wang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Huiyun Xu
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
- Research Center of Special Environmental Biomechanics & Medical Engineering, Northwestern Polytechnical University, Xi’an, China
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42
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Luo J, Jin Y, Li M, Dong L. Tumor suppressor miR‑613 induces cisplatin sensitivity in non‑small cell lung cancer cells by targeting GJA1. Mol Med Rep 2021; 23:385. [PMID: 33760215 PMCID: PMC7986010 DOI: 10.3892/mmr.2021.12024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 11/02/2020] [Indexed: 12/25/2022] Open
Abstract
It has been reported that microRNAs (miRs) contribute to several biological functions and are associated with drug resistance in various types of cancer. However, to the best of our knowledge, whether miR‑613 can affect cisplatin (CDDP) sensitivity in non‑small cell lung cancer (NSCLC) remains unknown. Reverse transcription‑quantitative PCR was performed to detect the expression levels of miR‑613 and gap junction α‑1 protein (GJA1) in patients with NSCLC. Cell Counting Kit‑8, colony formation and Transwell assays were employed to exam the effects of miR‑613 and GJA1 on cell functions. Cell apoptosis was analyzed using flow cytometry. An in vivo experiment was conducted to determine the influence of miR‑613 on tumor formation. In the present study, miR‑613 was revealed to be significantly downregulated in lung cancer tissues compared with in adjacent normal tissues, and low miR‑613 expression indicated a poor prognosis. Furthermore, cell proliferation, colony formation and migration of lung cancer cells were inhibited by overexpression of miR‑613. In vivo experiments also demonstrated that miR‑613 could inhibit tumor growth. Moreover, miR‑613 could enhance the negative effects of CDDP on cell proliferation, apoptosis and migration. GJA1 was revealed to be a target gene of miR‑613 and was upregulated in human lung cancer tissues. Rescue experiments demonstrated that miR‑613 increased the chemosensitivity of lung cancer cells by targeting GJA1. Collectively, the results suggested a tumor suppressor role of miR‑613 in NSCLC and indicated that miR‑613 could strengthen CDDP sensitivity in NSCLC cells by targeting GJA1, which may provide a novel therapeutic target for NSCLC.
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Affiliation(s)
- Jianhua Luo
- Department of Respiratory Medicine, Taizhou Municipal Hospital, Taizhou, Zhejiang 318000, P.R. China
| | - Yan Jin
- Department of Respiratory Medicine, Taizhou Municipal Hospital, Taizhou, Zhejiang 318000, P.R. China
| | - Mengyuan Li
- Department of Respiratory Medicine, Taizhou Municipal Hospital, Taizhou, Zhejiang 318000, P.R. China
| | - Liyang Dong
- Department of Invasive Technology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325000, P.R. China
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43
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Connexins in the Heart: Regulation, Function and Involvement in Cardiac Disease. Int J Mol Sci 2021; 22:ijms22094413. [PMID: 33922534 PMCID: PMC8122935 DOI: 10.3390/ijms22094413] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
Connexins are a family of transmembrane proteins that play a key role in cardiac physiology. Gap junctional channels put into contact the cytoplasms of connected cardiomyocytes, allowing the existence of electrical coupling. However, in addition to this fundamental role, connexins are also involved in cardiomyocyte death and survival. Thus, chemical coupling through gap junctions plays a key role in the spreading of injury between connected cells. Moreover, in addition to their involvement in cell-to-cell communication, mounting evidence indicates that connexins have additional gap junction-independent functions. Opening of unopposed hemichannels, located at the lateral surface of cardiomyocytes, may compromise cell homeostasis and may be involved in ischemia/reperfusion injury. In addition, connexins located at non-canonical cell structures, including mitochondria and the nucleus, have been demonstrated to be involved in cardioprotection and in regulation of cell growth and differentiation. In this review, we will provide, first, an overview on connexin biology, including their synthesis and degradation, their regulation and their interactions. Then, we will conduct an in-depth examination of the role of connexins in cardiac pathophysiology, including new findings regarding their involvement in myocardial ischemia/reperfusion injury, cardiac fibrosis, gene transcription or signaling regulation.
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44
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Wang Q, Liu S. Analysis of Hemichannels and Gap Junctions: Application and Extension of the Passive Transmembrane Ion Transport Model. Front Cell Neurosci 2021; 15:596953. [PMID: 33897368 PMCID: PMC8058385 DOI: 10.3389/fncel.2021.596953] [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: 09/29/2020] [Accepted: 02/15/2021] [Indexed: 02/02/2023] Open
Abstract
Electrical synaptic transmission is an essential form of interneuronal communication which is mediated by gap junctions that permit ion flow. Three gene families (connexins, innexins, and pannexins) have evolved to form gap junctional channels. Each gap junctional channel is formed by the docking of the hemichannel of one cell with the corresponding hemichannel of an adjacent cell. To date, there has been a lack of study models to describe this structure in detail. In this study, we demonstrate that numerical simulations suggest that the passive transmembrane ion transport model, based on the generality of ion channels, also applies to hemichannels in non-junctional plasma membranes. On this basis, we established a gap junctional channel model, which describes hemichannels' docking. We simulated homotypic and heterotypic gap junctions formed by connexins, innexins, and pannexins. Based on the numerical results and our theoretical model, we discussed the physiology of hemichannels and gap junctions, including ion blockage of hemichannels, voltage gating of gap junctions, and asymmetry and delay of electrical synaptic transmission, for which the numerical simulations are first comprehensively realized.
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Affiliation(s)
- Qiqian Wang
- School of Mathematics, South China University of Technology, Guangzhou, China
| | - Shenquan Liu
- School of Mathematics, South China University of Technology, Guangzhou, China
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45
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Abstract
Connexins are a family of gap junction forming proteins widely expressed by mammalian cells. They assemble into hexameric hemichannels, which can either function independently or dock with opposing hemichannels on apposite cells, forming a gap junction. Pannexins are structurally related to the connexins but extensive glycosylation of these channels prevents docking to form gap junctions and they function as membrane channels. Platelets express pannexin-1 and several connexin family members (Cx37, Cx40 and Cx62). These channels are permeable to molecules up to 1,000 Daltons in molecular mass and functional studies demonstrate their role in non-vesicular ATP release. Channel activation is regulated by (patho)physiological stimuli, such as mechanical stimulation, making them attractive potential drug targets for the management of arterial thrombosis. This review explores the structure and function of platelet pannexin-1 and connexins, the mechanisms by which they are gated and their therapeutic potential.
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Affiliation(s)
- Kirk A Taylor
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK.,National Heart and Lung Institute, Imperial College London, London, UK
| | - Gemma Little
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, UK
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46
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Hirschhäuser C, Lissoni A, Görge PM, Lampe PD, Heger J, Schlüter KD, Leybaert L, Schulz R, Boengler K. Connexin 43 phosphorylation by casein kinase 1 is essential for the cardioprotection by ischemic preconditioning. Basic Res Cardiol 2021; 116:21. [PMID: 33751227 PMCID: PMC7985055 DOI: 10.1007/s00395-021-00861-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 03/10/2021] [Indexed: 02/07/2023]
Abstract
Myocardial connexin 43 (Cx43) forms gap junctions and hemichannels, and is also present within subsarcolemmal mitochondria. The protein is phosphorylated by several kinases including mitogen-activated protein kinase (MAPK), protein kinase C (PKC), and casein kinase 1 (CK1). A reduction in Cx43 content abrogates myocardial infarct size reduction by ischemic preconditioning (IPC). The present study characterizes the contribution of Cx43 phosphorylation towards mitochondrial function, hemichannel activity, and the cardioprotection by IPC in wild-type (WT) mice and in mice in which Cx43-phosphorylation sites targeted by above kinases are mutated to non-phosphorylatable residues (Cx43MAPKmut, Cx43PKCmut, and Cx43CK1mut mice). The amount of Cx43 in the left ventricle and in mitochondria was reduced in all mutant strains compared to WT mice and Cx43 phosphorylation was altered at residues not directly targeted by the mutations. Whereas complex 1 respiration was reduced in all strains, complex 2 respiration was decreased in Cx43CK1mut mice only. In Cx43 epitope-mutated mice, formation of reactive oxygen species and opening of the mitochondrial permeability transition pore were not affected. The hemichannel open probability was reduced in Cx43PKCmut and Cx43CK1mut but not in Cx43MAPKmut cardiomyocytes. Infarct size in isolated saline-perfused hearts after ischemia/reperfusion (45 min/120 min) was comparable between genotypes and was significantly reduced by IPC (3 × 3 min ischemia/5 min reperfusion) in WT, Cx43MAPKmut, and Cx43PKCmut, but not in Cx43CK1mut mice, an effect independent from the amount of Cx43 and the probability of hemichannel opening. Taken together, our study shows that alterations of Cx43 phosphorylation affect specific cellular functions and highlights the importance of Cx43 phosphorylation by CK1 for IPC's cardioprotection.
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Affiliation(s)
- Christine Hirschhäuser
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany
| | - Alessio Lissoni
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | | | - Paul D Lampe
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Jacqueline Heger
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany
| | - Klaus-Dieter Schlüter
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Rainer Schulz
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany
| | - Kerstin Boengler
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany.
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47
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Yang ZJ, Zhang LL, Bi QC, Gan LJ, Wei MJ, Hong T, Tan RJ, Lan XM, Liu LH, Han XJ, Jiang LP. Exosomal connexin 43 regulates the resistance of glioma cells to temozolomide. Oncol Rep 2021; 45:44. [PMID: 33649836 PMCID: PMC7934218 DOI: 10.3892/or.2021.7995] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 01/25/2021] [Indexed: 12/21/2022] Open
Abstract
Glioblastoma is the most common and aggressive brain tumor and it is characterized by a high mortality rate. Temozolomide (TMZ) is an effective chemotherapy drug for glioblastoma, but the resistance to TMZ has come to represent a major clinical problem, and its underlying mechanism has yet to be elucidated. In the present study, the role of exosomal connexin 43 (Cx43) in the resistance of glioma cells to TMZ and cell migration was investigated. First, higher expression levels of Cx43 were detected in TMZ‑resistant U251 (U251r) cells compared with those in TMZ‑sensitive (U251s) cells. Exosomes from U251s or U251r cells (sExo and rExo, respectively) were isolated. It was found that the expression of Cx43 in rExo was notably higher compared with that in sExo, whereas treatment with rExo increased the expression of Cx43 in U251s cells. Additionally, exosomes stained with dioctadecyloxacarbocyanine (Dio) were used to visualized exosome uptake by glioma cells. It was observed that the uptake of Dio‑stained rExo in U251s cells was more prominent compared with that of Dio‑stained sExo, while 37,43Gap27, a gap junction mimetic peptide directed against Cx43, alleviated the rExo uptake by cells. Moreover, rExo increased the IC50 of U251s to TMZ, colony formation and Bcl‑2 expression, but decreased Bax and cleaved caspase‑3 expression in U251s cells. 37,43Gap27 efficiently inhibited these effects of rExo on U251s cells. Finally, the results of the wound healing and Transwell assays revealed that rExo significantly enhanced the migration of U251s cells, whereas 37,43Gap27 significantly attenuated rExo‑induced cell migration. Taken together, these results indicate the crucial role of exosomal Cx43 in chemotherapy resistance and migration of glioma cells, and suggest that Cx43 may hold promise as a therapeutic target for glioblastoma in the future.
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Affiliation(s)
- Zhang-Jian Yang
- Department of Pharmacology, School of Pharmaceutical Science, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Le-Ling Zhang
- Department of Pharmacology, School of Pharmaceutical Science, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Qiu-Chen Bi
- Department of Pharmacology, School of Pharmaceutical Science, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Li-Jun Gan
- Department of Pharmacology, School of Pharmaceutical Science, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Min-Jun Wei
- Department of Neurosurgery, First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Tao Hong
- Department of Neurosurgery, First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Ren-Jie Tan
- Department of Pharmacology, School of Pharmaceutical Science, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Xue-Mei Lan
- Department of Pharmacology, School of Pharmaceutical Science, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Li-Hua Liu
- Department of Pharmacology, School of Pharmaceutical Science, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Xiao-Jian Han
- Key Laboratory of Drug Targets and Drug Screening of Jiangxi Province, Nanchang, Jiangxi 330006, P.R. China
| | - Li-Ping Jiang
- Department of Pharmacology, School of Pharmaceutical Science, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
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48
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Ilyaskin AV, Korbmacher C, Diakov A. Inhibition of the epithelial sodium channel (ENaC) by connexin 30 involves stimulation of clathrin-mediated endocytosis. J Biol Chem 2021; 296:100404. [PMID: 33577799 PMCID: PMC7973139 DOI: 10.1016/j.jbc.2021.100404] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/05/2021] [Accepted: 02/08/2021] [Indexed: 01/16/2023] Open
Abstract
Mice lacking connexin 30 (Cx30) display increased epithelial sodium channel (ENaC) activity in the distal nephron and develop salt-sensitive hypertension. This indicates a functional link between Cx30 and ENaC, which remains incompletely understood. Here, we explore the effect of Cx30 on ENaC function using the Xenopus laevis oocyte expression system. Coexpression of human Cx30 with human αβγENaC significantly reduced ENaC-mediated whole-cell currents. The size of the inhibitory effect on ENaC depended on the expression level of Cx30 and required Cx30 ion channel activity. ENaC inhibition by Cx30 was mainly due to reduced cell surface ENaC expression resulting from enhanced ENaC retrieval without discernible effects on proteolytic channel activation and single-channel properties. ENaC retrieval from the cell surface involves the interaction of the ubiquitin ligase Nedd4-2 with PPPxY-motifs in the C-termini of ENaC. Truncating the C- termini of β- or γENaC significantly reduced the inhibitory effect of Cx30 on ENaC. In contrast, mutating the prolines belonging to the PPPxY-motif in γENaC or coexpressing a dominant-negative Xenopus Nedd4 (xNedd4-CS) did not significantly alter ENaC inhibition by Cx30. Importantly, the inhibitory effect of Cx30 on ENaC was significantly reduced by Pitstop-2, an inhibitor of clathrin-mediated endocytosis, or by mutating putative clathrin adaptor protein 2 (AP-2) recognition motifs (YxxФ) in the C termini of β- or γ-ENaC. In conclusion, our findings suggest that Cx30 inhibits ENaC by promoting channel retrieval from the plasma membrane via clathrin-dependent endocytosis. Lack of this inhibition may contribute to increased ENaC activity and salt-sensitive hypertension in mice with Cx30 deficiency.
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Affiliation(s)
- Alexandr V Ilyaskin
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | - Alexei Diakov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
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49
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Riquelme MA, Gu S, Hua R, Jiang JX. Mechanotransduction via the coordinated actions of integrins, PI3K signaling and Connexin hemichannels. Bone Res 2021; 9:8. [PMID: 33531460 PMCID: PMC7854719 DOI: 10.1038/s41413-020-00126-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 09/25/2020] [Accepted: 10/14/2020] [Indexed: 12/11/2022] Open
Abstract
Mechanical loading opens connexin 43 (Cx43) hemichannels (HCs), leading to the release of bone anabolic molecules, such as prostaglandins, from mechanosensitive osteocytes, which is essential for bone formation and remodeling. However, the mechanotransduction mechanism that activates HCs remains elusive. Here, we report a unique pathway by which mechanical signals are effectively transferred between integrin molecules located in different regions of the cell, resulting in HC activation. Both integrin α5 and αV were activated upon mechanical stimulation via either fluid dropping or flow shear stress (FSS). Inhibition of integrin αV activation or ablation of integrin α5 prevented HC opening on the cell body when dendrites were mechanically stimulated, suggesting mechanical transmission from the dendritic integrin αV to α5 in the cell body during HC activation. In addition, HC function was compromised in vivo, as determined by utilizing an antibody blocking αV activation and α5-deficient osteocyte-specific knockout mice. Furthermore, inhibition of integrin αV activation, but not that of α5, attenuated activation of the phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT) signaling pathway upon mechanical loading, and the inhibition of PI3K/AKT activation blocked integrin α5 activation and HC opening. Moreover, HC opening was blocked only by an anti-integrin αV antibody at low but not high FSS levels, suggesting that dendritic αV is a more sensitive mechanosensor than α5 for activating HCs. Together, these results reveal a new molecular mechanism of mechanotransduction involving the coordinated actions of integrins and PI3K/AKT in osteocytic dendritic processes and cell bodies that leads to HC opening and the release of key bone anabolic factors.
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Affiliation(s)
- Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229-3900, USA
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229-3900, USA
| | - Rui Hua
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229-3900, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229-3900, USA.
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50
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Hua R, Zhang J, Riquelme MA, Jiang JX. Connexin Gap Junctions and Hemichannels Link Oxidative Stress to Skeletal Physiology and Pathology. Curr Osteoporos Rep 2021; 19:66-74. [PMID: 33403446 PMCID: PMC8174533 DOI: 10.1007/s11914-020-00645-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/16/2020] [Indexed: 12/15/2022]
Abstract
PURPOSE OF REVIEW The goal of this review is to provide an overview of the impact and underlying mechanism of oxidative stress on connexin channel function, and their roles in skeletal aging, estrogen deficiency, and glucocorticoid excess associated bone loss. RECENT FINDINGS Connexin hemichannel opening is increased under oxidative stress conditions, which confers a cell protective role against oxidative stress-induced cell death. Oxidative stress acts as a key contributor to aging, estrogen deficiency, and glucocorticoid excess-induced osteoporosis and impairs osteocytic network and connexin gap junction communication. This paper reviews the current knowledge for the role of oxidative stress and connexin channels in the pathogenesis of osteoporosis and physiological and pathological responses of connexin channels to oxidative stress. Oxidative stress decreases osteocyte viability and impairs the balance of anabolic and catabolic responses. Connexin 43 (Cx43) channels play a critical role in bone remodeling, mechanotransduction, and survival of osteocytes. Under oxidative stress conditions, there is a consistent reduction of Cx43 expression, while the opening of Cx43 hemichannels protects osteocytes against cell injury caused by oxidative stress.
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Affiliation(s)
- Rui Hua
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Jingruo Zhang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA.
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