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Bayraktar E, Lopez-Pigozzi D, Bortolozzi M. Calcium Regulation of Connexin Hemichannels. Int J Mol Sci 2024; 25:6594. [PMID: 38928300 PMCID: PMC11204158 DOI: 10.3390/ijms25126594] [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: 05/01/2024] [Revised: 06/07/2024] [Accepted: 06/12/2024] [Indexed: 06/28/2024] Open
Abstract
Connexin hemichannels (HCs) expressed at the plasma membrane of mammalian cells are of paramount importance for intercellular communication. In physiological conditions, HCs can form gap junction (GJ) channels, providing a direct diffusive path between neighbouring cells. In addition, unpaired HCs provide conduits for the exchange of solutes between the cytoplasm and the extracellular milieu, including messenger molecules involved in paracrine signalling. The synergistic action of membrane potential and Ca2+ ions controls the gating of the large and relatively unselective pore of connexin HCs. The four orders of magnitude difference in gating sensitivity to the extracellular ([Ca2+]e) and the cytosolic ([Ca2+]c) Ca2+ concentrations suggests that at least two different Ca2+ sensors may exist. While [Ca2+]e acts as a spatial modulator of the HC opening, which is most likely dependent on the cell layer, compartment, and organ, [Ca2+]c triggers HC opening and the release of extracellular bursts of messenger molecules. Such molecules include ATP, cAMP, glutamate, NAD+, glutathione, D-serine, and prostaglandins. Lost or abnormal HC regulation by Ca2+ has been associated with several diseases, including deafness, keratitis ichthyosis, palmoplantar keratoderma, Charcot-Marie-Tooth neuropathy, oculodentodigital dysplasia, and congenital cataracts. The fact that both an increased and a decreased Ca2+ sensitivity has been linked to pathological conditions suggests that Ca2+ in healthy cells finely tunes the normal HC function. Overall, further investigation is needed to clarify the structural and chemical modifications of connexin HCs during [Ca2+]e and [Ca2+]c variations. A molecular model that accounts for changes in both Ca2+ and the transmembrane voltage will undoubtedly enhance our interpretation of the experimental results and pave the way for developing therapeutic compounds targeting specific HC dysfunctions.
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Affiliation(s)
- Erva Bayraktar
- Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Via Marzolo 8, 35131 Padova, Italy
| | - Diego Lopez-Pigozzi
- Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Via Marzolo 8, 35131 Padova, Italy
| | - Mario Bortolozzi
- Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Via Marzolo 8, 35131 Padova, Italy
- Institute of Endocrinology and Oncology “Gaetano Salvatore” (IEOS-CNR), Via Pietro Castellino 111, 80131 Napoli, Italy
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2
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Villanelo F, Minogue PJ, Maripillán J, Reyna-Jeldes M, Jensen-Flores J, García IE, Beyer EC, Pérez-Acle T, Berthoud VM, Martínez AD. Connexin channels and hemichannels are modulated differently by charge reversal at residues forming the intracellular pocket. Biol Res 2024; 57:31. [PMID: 38783330 PMCID: PMC11112876 DOI: 10.1186/s40659-024-00501-5] [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: 05/17/2023] [Accepted: 04/16/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND Members of the β-subfamily of connexins contain an intracellular pocket surrounded by amino acid residues from the four transmembrane helices. The presence of this pocket has not previously been investigated in members of the α-, γ-, δ-, and ε-subfamilies. We studied connexin50 (Cx50) as a representative of the α-subfamily, because its structure has been determined and mutations of Cx50 are among the most common genetic causes of congenital cataracts. METHODS To investigate the presence and function of the intracellular pocket in Cx50 we used molecular dynamics simulation, site-directed mutagenesis, gap junction tracer intercellular transfer, and hemichannel activity detected by electrophysiology and by permeation of charged molecules. RESULTS Employing molecular dynamics, we determined the presence of the intracellular pocket in Cx50 hemichannels and identified the amino acids participating in its formation. We utilized site-directed mutagenesis to alter a salt-bridge interaction that supports the intracellular pocket and occurs between two residues highly conserved in the connexin family, R33 and E162. Substitution of opposite charges at either position decreased formation of gap junctional plaques and cell-cell communication and modestly reduced hemichannel currents. Simultaneous charge reversal at these positions produced plaque-forming non-functional gap junction channels with highly active hemichannels. CONCLUSIONS These results show that interactions within the intracellular pocket influence both gap junction channel and hemichannel functions. Disruption of these interactions may be responsible for diseases associated with mutations at these positions.
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Affiliation(s)
- Felipe Villanelo
- Computational Biology Lab, Centro Basal Ciencia & Vida, Santiago, 8580702, Chile
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Bellavista 7, Recoleta, Santiago, Chile
| | - Peter J Minogue
- Department of Pediatrics, University of Chicago, Chicago, IL, 60637, USA
| | - Jaime Maripillán
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Universidad de Valparaíso, Valparaíso, Chile
| | - Mauricio Reyna-Jeldes
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Universidad de Valparaíso, Valparaíso, Chile
| | - Joaquin Jensen-Flores
- Computational Biology Lab, Centro Basal Ciencia & Vida, Santiago, 8580702, Chile
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Bellavista 7, Recoleta, Santiago, Chile
| | - Isaac E García
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Universidad de Valparaíso, Valparaíso, Chile
- Laboratorio de Fisiología Molecular y Biofísica, Facultad de Odontología, Universidad de Valparaíso, Valparaíso, Chile
- Centro de Investigación en Ciencias Odontológicas y Médicas, Universidad de Valparaíso, Valparaíso, Chile
| | - Eric C Beyer
- Department of Pediatrics, University of Chicago, Chicago, IL, 60637, USA
| | - Tomás Pérez-Acle
- Computational Biology Lab, Centro Basal Ciencia & Vida, Santiago, 8580702, Chile
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Bellavista 7, Recoleta, Santiago, Chile
| | - Viviana M Berthoud
- Department of Pediatrics, University of Chicago, Chicago, IL, 60637, USA.
| | - Agustín D Martínez
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Universidad de Valparaíso, Valparaíso, Chile.
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Luo Y, Zheng S, Xiao W, Zhang H, Li Y. Pannexins in the musculoskeletal system: new targets for development and disease progression. Bone Res 2024; 12:26. [PMID: 38705887 PMCID: PMC11070431 DOI: 10.1038/s41413-024-00334-8] [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: 12/08/2023] [Revised: 03/04/2024] [Accepted: 04/01/2024] [Indexed: 05/07/2024] Open
Abstract
During cell differentiation, growth, and development, cells can respond to extracellular stimuli through communication channels. Pannexin (Panx) family and connexin (Cx) family are two important types of channel-forming proteins. Panx family contains three members (Panx1-3) and is expressed widely in bone, cartilage and muscle. Although there is no sequence homology between Panx family and Cx family, they exhibit similar configurations and functions. Similar to Cxs, the key roles of Panxs in the maintenance of physiological functions of the musculoskeletal system and disease progression were gradually revealed later. Here, we seek to elucidate the structure of Panxs and their roles in regulating processes such as osteogenesis, chondrogenesis, and muscle growth. We also focus on the comparison between Cx and Panx. As a new key target, Panxs expression imbalance and dysfunction in muscle and the therapeutic potentials of Panxs in joint diseases are also discussed.
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Affiliation(s)
- Yan Luo
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China
- Department of Clinical Medicine, Xiangya Medicine School, Central South University, Changsha, Hunan, 410008, China
| | - Shengyuan Zheng
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China
- Department of Clinical Medicine, Xiangya Medicine School, Central South University, Changsha, Hunan, 410008, China
| | - Wenfeng Xiao
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China
| | - Hang Zhang
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
| | - Yusheng Li
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China.
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China.
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4
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Lucaciu SA, Leighton SE, Hauser A, Yee R, Laird DW. Diversity in connexin biology. J Biol Chem 2023; 299:105263. [PMID: 37734551 PMCID: PMC10598745 DOI: 10.1016/j.jbc.2023.105263] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 09/08/2023] [Accepted: 09/14/2023] [Indexed: 09/23/2023] Open
Abstract
Over 35 years ago the cell biology community was introduced to connexins as the subunit employed to assemble semicrystalline clusters of intercellular channels that had been well described morphologically as gap junctions. The decade that followed would see knowledge of the unexpectedly large 21-member human connexin family grow to reflect unique and overlapping expression patterns in all organ systems. While connexin biology initially focused on their role in constructing highly regulated intercellular channels, this was destined to change as discoveries revealed that connexin hemichannels at the cell surface had novel roles in many cell types, especially when considering connexin pathologies. Acceptance of connexins as having bifunctional channel properties was initially met with some resistance, which has given way in recent years to the premise that connexins have multifunctional properties. Depending on the connexin isoform and cell of origin, connexins have wide-ranging half-lives that vary from a couple of hours to the life expectancy of the cell. Diversity in connexin channel characteristics and molecular properties were further revealed by X-ray crystallography and single-particle cryo-EM. New avenues have seen connexins or connexin fragments playing roles in cell adhesion, tunneling nanotubes, extracellular vesicles, mitochondrial membranes, transcription regulation, and in other emerging cellular functions. These discoveries were largely linked to Cx43, which is prominent in most human organs. Here, we will review the evolution of knowledge on connexin expression in human adults and more recent evidence linking connexins to a highly diverse array of cellular functions.
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Affiliation(s)
- Sergiu A Lucaciu
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Stephanie E Leighton
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | - Alexandra Hauser
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | - Ryan Yee
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Dale W Laird
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
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Wang G, Qin S, Geng H, Zheng Y, Li R, Xia C, Chen L, Yao J, Deng L. Resveratrol Promotes Gluconeogenesis by Inhibiting SESN2-mTORC2-AKT Pathway in Calf Hepatocytes. J Nutr 2023; 153:1930-1943. [PMID: 37182694 DOI: 10.1016/j.tjnut.2023.05.005] [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: 03/02/2023] [Revised: 04/27/2023] [Accepted: 05/02/2023] [Indexed: 05/16/2023] Open
Abstract
BACKGROUND The glucose requirement of dairy cows is mainly met by increasing the rate of hepatic gluconeogenesis. However, due to negative energy balance, the liver of periparturient cows is under oxidative stress induced by lipid over-mobilization, and hepatic gluconeogenesis is reduced. Studies have demonstrated that resveratrol, which is widely known for its antioxidant properties, can alter hepatic gluconeogenesis. However, it is not clear whether resveratrol could regulate hepatic gluconeogenesis by its antioxidant properties. OBJECTIVES This study aims to investigate the precise effect of resveratrol in hepatic gluconeogenesis, the role of resveratrol on hydrogen peroxide (H2O2)-induced oxidative stress in hepatocytes and the potential mechanism using primary hepatocytes. METHODS Primary hepatocytes were isolated from 5 healthy Holstein calves (1 d old, 30 to 40 kg, fasted) and treated with different concentrations of resveratrol (0, 5, 10, 25, or 50 μM) combined with or without H2O2 (0, 100, or 200 μM) induction for 12 h. RESULTS Resveratrol enhanced the expression of gluconeogenic genes of calf hepatocytes in a dose-dependent manner (P < 0.05). Conversely, H2O2 suppressed the expression of gluconeogenic genes and induced oxidative stress (P < 0.05), which was improved by resveratrol in calf hepatocytes (P < 0.001). Furthermore, the mechanistic target of rapamycin complex 2 (mTORC2)-AKT pathway was found to negatively regulate gluconeogenesis. An AKT inhibitor was used to assess the role of the mTORC2-AKT pathway in the effects of resveratrol. The results showed resveratrol promoted hepatic gluconeogenesis by inhibiting the mTORC2-AKT pathway. Moreover, sestrin 2 (SESN2) upregulated the activity of mTORC2. We further found that resveratrol decreased SESN2 levels (P < 0.001). CONCLUSIONS This study indicated that resveratrol enhances the gluconeogenic capacity of calf hepatocytes by improving H2O2-induced oxidative stress and modulating the activity of the SESN2-mTORC2-AKT pathway, implying that resveratrol may be a promising target for ameliorating liver oxidative stress in transition cows.
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Affiliation(s)
- GuoYan Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - SenLin Qin
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - HuiJun Geng
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Yining Zheng
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Rongnuo Li
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Chao Xia
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Lei Chen
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - JunHu Yao
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China.
| | - Lu Deng
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China.
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Zhao D, Wu J, Acosta FM, Xu H, Jiang JX. Connexin 43 hemichannels and prostaglandin E 2 release in anabolic function of the skeletal tissue to mechanical stimulation. Front Cell Dev Biol 2023; 11:1151838. [PMID: 37123401 PMCID: PMC10133519 DOI: 10.3389/fcell.2023.1151838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 04/05/2023] [Indexed: 05/02/2023] Open
Abstract
Bone adapts to changes in the physical environment by modulating remodeling through bone resorption and formation to maintain optimal bone mass. As the most abundant connexin subtype in bone tissue, connexin 43 (Cx43)-forming hemichannels are highly responsive to mechanical stimulation by permitting the exchange of small molecules (<1.2 kDa) between bone cells and the extracellular environment. Upon mechanical stimulation, Cx43 hemichannels facilitate the release of prostaglandins E2 (PGE2), a vital bone anabolic factor from osteocytes. Although most bone cells are involved in mechanosensing, osteocytes are the principal mechanosensitive cells, and PGE2 biosynthesis is greatly enhanced by mechanical stimulation. Mechanical stimulation-induced PGE2 released from osteocytic Cx43 hemichannels acts as autocrine effects that promote β-catenin nuclear accumulation, Cx43 expression, gap junction function, and protects osteocytes against glucocorticoid-induced osteoporosis in cultured osteocytes. In vivo, Cx43 hemichannels with PGE2 release promote bone formation and anabolism in response to mechanical loading. This review summarizes current in vitro and in vivo understanding of Cx43 hemichannels and extracellular PGE2 release, and their roles in bone function and mechanical responses. Cx43 hemichannels could be a significant potential new therapeutic target for treating bone loss and osteoporosis.
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Affiliation(s)
- Dezhi Zhao
- School of Medicine, Northwest University, Xi’an, China
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
- School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Jiawei Wu
- School of Medicine, Northwest University, Xi’an, China
| | - Francisca M. Acosta
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - Huiyun Xu
- 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
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The Impact of Plasma Membrane Ion Channels on Bone Remodeling in Response to Mechanical Stress, Oxidative Imbalance, and Acidosis. Antioxidants (Basel) 2023; 12:antiox12030689. [PMID: 36978936 PMCID: PMC10045377 DOI: 10.3390/antiox12030689] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/01/2023] [Accepted: 03/03/2023] [Indexed: 03/14/2023] Open
Abstract
The extracellular milieu is a rich source of different stimuli and stressors. Some of them depend on the chemical–physical features of the matrix, while others may come from the ‘outer’ environment, as in the case of mechanical loading applied on the bones. In addition to these forces, a plethora of chemical signals drives cell physiology and fate, possibly leading to dysfunctions when the homeostasis is disrupted. This variety of stimuli triggers different responses among the tissues: bones represent a particular milieu in which a fragile balance between mechanical and metabolic demands should be tuned and maintained by the concerted activity of cell biomolecules located at the interface between external and internal environments. Plasma membrane ion channels can be viewed as multifunctional protein machines that act as rapid and selective dual-nature hubs, sensors, and transducers. Here we focus on some multisensory ion channels (belonging to Piezo, TRP, ASIC/EnaC, P2XR, Connexin, and Pannexin families) actually or potentially playing a significant role in bone adaptation to three main stressors, mechanical forces, oxidative stress, and acidosis, through their effects on bone cells including mesenchymal stem cells, osteoblasts, osteoclasts, and osteocytes. Ion channel-mediated bone remodeling occurs in physiological processes, aging, and human diseases such as osteoporosis, cancer, and traumatic events.
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Aging Hallmarks and the Role of Oxidative Stress. Antioxidants (Basel) 2023; 12:antiox12030651. [PMID: 36978899 PMCID: PMC10044767 DOI: 10.3390/antiox12030651] [Citation(s) in RCA: 66] [Impact Index Per Article: 66.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 02/26/2023] [Accepted: 03/01/2023] [Indexed: 03/08/2023] Open
Abstract
Aging is a complex biological process accompanied by a progressive decline in the physical function of the organism and an increased risk of age-related chronic diseases such as cardiovascular diseases, cancer, and neurodegenerative diseases. Studies have established that there exist nine hallmarks of the aging process, including (i) telomere shortening, (ii) genomic instability, (iii) epigenetic modifications, (iv) mitochondrial dysfunction, (v) loss of proteostasis, (vi) dysregulated nutrient sensing, (vii) stem cell exhaustion, (viii) cellular senescence, and (ix) altered cellular communication. All these alterations have been linked to sustained systemic inflammation, and these mechanisms contribute to the aging process in timing not clearly determined yet. Nevertheless, mitochondrial dysfunction is one of the most important mechanisms contributing to the aging process. Mitochondria is the primary endogenous source of reactive oxygen species (ROS). During the aging process, there is a decline in ATP production and elevated ROS production together with a decline in the antioxidant defense. Elevated ROS levels can cause oxidative stress and severe damage to the cell, organelle membranes, DNA, lipids, and proteins. This damage contributes to the aging phenotype. In this review, we summarize recent advances in the mechanisms of aging with an emphasis on mitochondrial dysfunction and ROS production.
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Zhou RX, Zhang YW, Cao MM, Liu CH, Rui YF, Li YJ. Linking the relation between gut microbiota and glucocorticoid-induced osteoporosis. J Bone Miner Metab 2023; 41:145-162. [PMID: 36912997 PMCID: PMC10010237 DOI: 10.1007/s00774-023-01415-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 02/27/2023] [Indexed: 03/14/2023]
Abstract
Osteoporosis (OP) is the most prevalent metabolic bone disease, characterized by the low bone mass and microarchitectural deterioration of bone tissue. Glucocorticoid (GC) clinically acts as one of the anti-inflammatory, immune-modulating, and therapeutic drugs, whereas the long-term use of GC may cause rapid bone resorption, followed by prolonged and profound suppression of bone formation, resulting in the GC-induced OP (GIOP). GIOP ranks the first among secondary OP and is a pivotal risk for fracture, as well as high disability rate and mortality, at both societal and personal levels, vital costs. Gut microbiota (GM), known as the "second gene pool" of human body, is highly correlated with maintaining the bone mass and bone quality, and the relation between GM and bone metabolism has gradually become a research hotspot. Herein, combined with recent studies and based on the cross-linking relationship between GM and OP, this review is aimed to discuss the potential mechanisms of GM and its metabolites on the OP, as well as the moderating effects of GC on GM, thereby providing an emerging thought for prevention and treatment of GIOP.
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Affiliation(s)
- Rui-Xin Zhou
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Yuan-Wei Zhang
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
- Department of Orthopaedics, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
- Multidisciplinary Team (MDT) for Geriatric Hip Fracture Management, Zhongda Hospital, School of Medicine, Southeast University, Nanjing , Jiangsu, China
- Orthopaedic Trauma Institute (OTI), Southeast University, Nanjing, Jiangsu, China
| | - Mu-Min Cao
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
- Department of Orthopaedics, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
- Multidisciplinary Team (MDT) for Geriatric Hip Fracture Management, Zhongda Hospital, School of Medicine, Southeast University, Nanjing , Jiangsu, China
- Orthopaedic Trauma Institute (OTI), Southeast University, Nanjing, Jiangsu, China
| | - Cun-Hao Liu
- School of Architecture, Southeast University, Nanjing, Jiangsu, China
| | - Yun-Feng Rui
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
- Department of Orthopaedics, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, China
- Multidisciplinary Team (MDT) for Geriatric Hip Fracture Management, Zhongda Hospital, School of Medicine, Southeast University, Nanjing , Jiangsu, China
- Orthopaedic Trauma Institute (OTI), Southeast University, Nanjing, Jiangsu, China
| | - Ying-Juan Li
- Department of Geriatrics, Zhongda Hospital, School of Medicine, Southeast University, No. 87 Ding Jia Qiao, Nanjing, 210009, Jiangsu, People's Republic of China.
- School of Medicine, Southeast University, Nanjing, Jiangsu, China.
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10
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Santo SGE, da Silva TC, Vinken M, Cogliati B, Barbisan LF, Romualdo GR. The Implications of Connexin 43 Deficiency during the Early Stages of Chemically Induced Mouse Colon Carcinogenesis. Antioxidants (Basel) 2022; 11:antiox11122368. [PMID: 36552579 PMCID: PMC9774636 DOI: 10.3390/antiox11122368] [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: 11/03/2022] [Revised: 11/24/2022] [Accepted: 11/26/2022] [Indexed: 12/03/2022] Open
Abstract
Colorectal cancer (CRC), associated with an increased intake of processed red meats, saturated fats, and simple carbohydrates accompanied by low dietary fiber, fruits, and vegetables consumption, presents a high epidemiological burden. Connexin43 (Cx43) protein, which forms gap junctions or hemichannels, has tumor suppressor or oncogenic activities in a cancer type- and stage-dependent manner. Cx43 expression varies during colon carcinogenesis, and its functional role is not fully understood. Thus, we evaluated the implications of Cx43 heterologous deletion (Cx43+/-) during the early stages of a chemically induced model of colon carcinogenesis. Female C57BL/6J mice (wild-type or Cx43+/-) were submitted to a colon carcinogenesis model induced by 1,2 dimethylhydrazine (DMH). Mice were euthanized eight hours (week 7) or 30 weeks (week 37) after the last DMH administration to evaluate subacute colon toxicity outcomes or the burden of (pre)neoplastic lesions, respectively. At week 7, Cx43 deficiency inferred no alterations in the DMH-induced increase in systemic (peripheral blood), in situ (colonocytes) DNA damage, and apoptosis in the colonocytes. At week 30, Cx43+/- mice presented an increase in preneoplastic aberrant crypt foci (ACF) multiplicity, while no alterations were observed in colorectal adenoma (CRA) occurrence, multiplicity, volume, proliferation, growth, and β-catenin immunoexpression. Similarly, an in silico analysis of human CRA showed decreased mRNA expression of Cx43 with no correlation with proliferation, apoptosis, and β-catenin markers. These findings indicate the discrete role of Cx43 in the early stages of chemically induced mouse colon carcinogenesis.
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Affiliation(s)
- Sara Gomes Espírito Santo
- Department of Pathology, Botucatu Medical School, São Paulo State University (UNESP), Botucatu 18618-687, São Paulo, Brazil
| | - Tereza Cristina da Silva
- School of Veterinary Medicine and Animal Science, University of São Paulo (USP), São Paulo 05508-270, São Paulo, Brazil
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium
| | - Bruno Cogliati
- School of Veterinary Medicine and Animal Science, University of São Paulo (USP), São Paulo 05508-270, São Paulo, Brazil
| | - Luís Fernando Barbisan
- Department of Structural and Functional Biology, Botucatu Medical School, São Paulo State University (UNESP), Botucatu 18618-689, São Paulo, Brazil
| | - Guilherme Ribeiro Romualdo
- Department of Pathology, Botucatu Medical School, São Paulo State University (UNESP), Botucatu 18618-687, São Paulo, Brazil
- Department of Structural and Functional Biology, Botucatu Medical School, São Paulo State University (UNESP), Botucatu 18618-689, São Paulo, Brazil
- Correspondence: ; Tel.: +55-1438800469
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11
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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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12
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Li G, Zhang L, Lu Z, Yang B, Yang H, Shang P, Jiang JX, Wang D, Xu H. Connexin 43 Channels in Osteocytes Are Necessary for Bone Mass and Skeletal Muscle Function in Aged Male Mice. Int J Mol Sci 2022; 23:13506. [PMID: 36362291 PMCID: PMC9654692 DOI: 10.3390/ijms232113506] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 10/24/2022] [Accepted: 11/03/2022] [Indexed: 09/26/2023] Open
Abstract
Osteoporosis and sarcopenia (termed "Osteosarcopenia"), the twin-aging diseases, are major contributors to reduced bone mass and muscle weakness in the elderly population. Connexin 43 (Cx43) in osteocytes has been previously reported to play vital roles in bone homeostasis and muscle function in mature mice. The Cx43-formed gap junctions (GJs) and hemichannels (HCs) in osteocytes are important portals for the exchange of small molecules in cell-to-cell and cell-to-extracellular matrix, respectively. However, the roles of Cx43-based GJs and HCs in both bone and muscle aging are still unclear. Here, we used two transgenic mouse models with overexpression of the dominant negative Cx43 mutants primarily in osteocytes driven by the 10-kb Dmp1 promoter, R76W mice (inhibited gap junctions but enhanced hemichannels) and Δ130-136 mice (both gap junction and hemichannels are inhibited), to determine the actions of Cx43-based hemichannels (HCs) and gap junctions (GJs) in the regulation of bone and skeletal muscle from aged mice (18 months) as compared with those from adult mice (10 months). We demonstrated that enhancement of Cx43 HCs reduces bone mass due to increased osteoclast surfaces while the impairment of Cx43 HCs increases osteocyte apoptosis in aged mice caused by reduced PGE2 levels. Furthermore, altered mitochondrial homeostasis with reduced expression of Sirt-1, OPA-1, and Drp-1 resulted in excessive ROS level in muscle soleus (SL) of aged transgenic mice. In vitro, the impairment of Cx43 HCs in osteocytes from aged mice also promoted muscle collagen synthesis through activation of TGFβ/smad2/3 signaling because of reduced PGE2 levels in the PO CM. These findings indicate that the enhancement of Cx43 HCs while GJs are inhibited reduces bone mass, and the impairment of Cx43 HCs inhibits PGE2 level in osteocytes and this reduction promotes muscle collagen synthesis in skeletal muscle through activation of TGFβ/smad2/3 signaling, which together with increased ROS level contributes to reduced muscle force in aged mice.
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Affiliation(s)
- Guobin Li
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an 710072, China
- College of Life Sciences, Inner Mongolia Agricultural University, Hohhot 010018, China
| | - Lan Zhang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an 710072, China
| | - Zhe Lu
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an 710072, China
| | - Baoqiang Yang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an 710072, China
| | - Hui Yang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an 710072, China
| | - Peng Shang
- Key Laboratory for Space Bioscience and Biotechnology, Research and Development Institute in Shenzhen, Northwestern Polytechnical University, Shenzhen 518057, China
| | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Dong’en Wang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an 710072, China
| | - Huiyun Xu
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an 710072, China
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13
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Oliveira MC, Verswyvel H, Smits E, Cordeiro RM, Bogaerts A, Lin A. The pro- and anti-tumoral properties of gap junctions in cancer and their role in therapeutic strategies. Redox Biol 2022; 57:102503. [PMID: 36228438 PMCID: PMC9557036 DOI: 10.1016/j.redox.2022.102503] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 09/06/2022] [Accepted: 10/06/2022] [Indexed: 11/24/2022] Open
Abstract
Gap junctions (GJs), essential structures for cell-cell communication, are made of two hemichannels (commonly called connexons), one on each adjacent cell. Found in almost all cells, GJs play a pivotal role in many physiological and cellular processes, and have even been linked to the progression of diseases, such as cancer. Modulation of GJs is under investigation as a therapeutic strategy to kill tumor cells. Furthermore, GJs have also been studied for their key role in activating anti-cancer immunity and propagating radiation- and oxidative stress-induced cell death to neighboring cells, a process known as the bystander effect. While, gap junction (GJ)-based therapeutic strategies are being developed, one major challenge has been the paradoxical role of GJs in both tumor progression and suppression, based on GJ composition, cancer factors, and tumoral context. Therefore, understanding the mechanisms of action, regulation, and the dual characteristics of GJs in cancer is critical for developing effective therapeutics. In this review, we provide an overview of the current understanding of GJs structure, function, and paradoxical pro- and anti-tumoral role in cancer. We also discuss the treatment strategies to target these GJs properties for anti-cancer responses, via modulation of GJ function.
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Affiliation(s)
- Maria C Oliveira
- Plasma Lab for Applications in Sustainability and Medicine-Antwerp (PLASMANT), Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium; Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Avenida dos Estados 5001, CEP 09210-580, Santo André, SP, Brazil.
| | - Hanne Verswyvel
- Plasma Lab for Applications in Sustainability and Medicine-Antwerp (PLASMANT), Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium; Center for Oncological Research (CORE), Integrated Personalized and Precision Oncology Network (IPPON), University of Antwerp, Universiteitsplein 1, B-2610, Antwerp, Belgium
| | - Evelien Smits
- Center for Oncological Research (CORE), Integrated Personalized and Precision Oncology Network (IPPON), University of Antwerp, Universiteitsplein 1, B-2610, Antwerp, Belgium
| | - Rodrigo M Cordeiro
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Avenida dos Estados 5001, CEP 09210-580, Santo André, SP, Brazil
| | - Annemie Bogaerts
- Plasma Lab for Applications in Sustainability and Medicine-Antwerp (PLASMANT), Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium
| | - Abraham Lin
- Plasma Lab for Applications in Sustainability and Medicine-Antwerp (PLASMANT), Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium; Center for Oncological Research (CORE), Integrated Personalized and Precision Oncology Network (IPPON), University of Antwerp, Universiteitsplein 1, B-2610, Antwerp, Belgium
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14
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Tu C, Lai S, Huang Z, Cai G, Zhao K, Gao J, Wu Z, Zhong Z. Accumulation of advanced oxidation protein products contributes to age-related impairment of gap junction intercellular communication in osteocytes of male mice. Bone Joint Res 2022; 11:413-425. [PMID: 35775164 PMCID: PMC9350704 DOI: 10.1302/2046-3758.117.bjr-2021-0554.r2] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
AIMS Gap junction intercellular communication (GJIC) in osteocytes is impaired by oxidative stress, which is associated with age-related bone loss. Ageing is accompanied by the accumulation of advanced oxidation protein products (AOPPs). However, it is still unknown whether AOPP accumulation is involved in the impairment of osteocytes' GJIC. This study aims to investigate the effect of AOPP accumulation on osteocytes' GJIC in aged male mice and its mechanism. METHODS Changes in AOPP levels, expression of connexin43 (Cx43), osteocyte network, and bone mass were detected in 18-month-old and three-month-old male mice. Cx43 expression, GJIC function, mitochondria membrane potential, reactive oxygen species (ROS) levels, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation were detected in murine osteocyte-like cells (MLOY4 cells) treated with AOPPs. The Cx43 expression, osteocyte network, bone mass, and mechanical properties were detected in three-month-old mice treated with AOPPs for 12 weeks. RESULTS The AOPP levels were increased in aged mice and correlated with degeneration of osteocyte network, loss of bone mass, and decreased Cx43 expression. AOPP intervention induced NADPH oxidase activation and mitochondrial dysfunction, triggered ROS generation, reduced Cx43 expression, and ultimately impaired osteocytes' GJIC, which were ameliorated by NADPH oxidase inhibitor apocynin, mitochondria-targeted superoxide dismutase mimetic (mito-TEMPO), and ROS scavenger N-acetyl cysteine. Chronic AOPP loading accelerated the degradation of osteocyte networks and decreased Cx43 expression, resulting in deterioration of bone mass and mechanical properties in vivo. CONCLUSION Our study suggests that AOPP accumulation contributes to age-related impairment of GJIC in osteocytes of male mice, which may be part of the pathogenic mechanism responsible for bone loss during ageing. Cite this article: Bone Joint Res 2022;11(7):413-425.
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Affiliation(s)
- Chen Tu
- Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Siqi Lai
- Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Zhiwei Huang
- Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Guixing Cai
- Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Kai Zhao
- Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Jiawen Gao
- Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Zhiyong Wu
- College of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
| | - Zhaoming Zhong
- Division of Spine Surgery, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China
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15
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Ding L, Wang J. MiR-106a facilitates the sensorineural hearing loss induced by oxidative stress by targeting connexin-43. Bioengineered 2022; 13:14080-14093. [PMID: 35730503 PMCID: PMC9342191 DOI: 10.1080/21655979.2022.2071021] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Sensorineural hearing loss (SNHL) is a common clinical side effect resulted from the overusing of aminoglycoside antibacterial drugs, such as gentamicin. Oxidative stress is recently evidenced to be an important inducer for SNHL, which is reported to be associated with the knockdown of connexin-43. MiR-106a is recently found as a regulator of connexin-43. The present study aims to investigate whether miR-106a is a vital mediator in the development of SNHL. Firstly, upregulated miR-106a was observed in the peripheral blood sample of SNHL patients. Glucose oxidase (GO) was utilized to induce oxidative injury in isolated rat cochlear marginal cells (MCs), followed by introducing the miR-106a inhibitor. We found that the declined proliferation ability, increased apoptosis, and activated oxidative stress in GO-stimulated MCs were dramatically abolished by the miR-106a inhibitor, accompanied by the upregulation of connexin-43. The targeting correlation between miR-106a and connexin-43 was predicted and confirmed by the dual luciferase gene reporter assay. Furthermore, the regulatory effect of miR-106a inhibitor against the proliferation, apoptosis, and oxidative stress in GO-treated MCs were dramatically abolished by the knockdown of connexin-43. Gentamicin was utilized to establish the SNHL model in rats, followed by the treatments of antagomir-106a and antagomir-106a combined with carbenoxolone, an inhibitor of connexin-43. The alleviated pathological state, reduced apoptosis, and ameliorated oxidative stress in cochlea tissues were observed in antagomir-106a treated SNHL rats, which were dramatically reversed by the co-administration of carbenoxolone. Collectively, miR-106a facilitated the SNHL induced by oxidative stress via targeting connexin-43.
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Affiliation(s)
- Lei Ding
- ENT Department, Beijing University of Chinese Medicine Subsidiary Dongfang Hospital, Beijing, China
| | - Jiaxi Wang
- ENT Department, Beijing University of Chinese Medicine Subsidiary Dongfang Hospital, Beijing, China
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16
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Kawatsura R, Hara Y, Akiyama M, Tachikawa N, Nakahama KI. Gap junctional intercellular communication attenuates osteoclastogenesis induced by activated osteoblasts. Biochem Biophys Res Commun 2022; 597:71-76. [PMID: 35124462 DOI: 10.1016/j.bbrc.2022.01.118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 01/29/2022] [Indexed: 11/02/2022]
Abstract
Osteoblasts participate in both bone formation through the synthesis of extracellular matrix and osteoclast differentiation through the expression of osteoclast differentiation factor. Osteoblasts communicate with each other via gap junctions (GJ), which enable small molecules, such as cAMP, to move to adjacent cells. Therefore, we focused on the role of cAMP propagation between osteoblasts via GJ in the osteoclast-supporting activity of osteoblasts. Osteoclast-supporting activity was evaluated by a co-culture system of osteoblasts with bone marrow-derived mononuclear cells. In this system, ablation of Gja1, a gene encoding connexin 43, in osteoblasts promoted osteoclastogenesis induced by prostaglandin E2 (PGE2). A phosphodiesterase 4 inhibitor increased both osteoclastogenesis and the intracellular cAMP concentration ([cAMP]i) in osteoblasts. Individual cell analysis of [cAMP]i in osteoblasts revealed different responses of each osteoblast to PGE2. Moreover, measurement of real-time [cAMP]i demonstrated cAMP movement from cell to cell via GJ. The inhibition of GJ resulted in the upregulation of [cAMP]i in osteoblasts stimulated by PGE2. This study suggested that GJ intercellular communication exerts protective effects against excess osteoclastogenesis via cAMP movement between osteoblasts.
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Affiliation(s)
- Risa Kawatsura
- Department of Cellular Physiological Chemistry, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan; Regenerative and Reconstructive Oral Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Yusuke Hara
- Department of Cellular Physiological Chemistry, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Masako Akiyama
- Research Administration Division, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Noriko Tachikawa
- Regenerative and Reconstructive Oral Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Ken-Ichi Nakahama
- Department of Cellular Physiological Chemistry, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
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17
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An S, Zheng S, Cai Z, Chen S, Wang C, Li Y, Deng Z. Connexin43 in Musculoskeletal System: New Targets for Development and Disease Progression. Aging Dis 2022; 13:1715-1732. [DOI: 10.14336/ad.2022.0421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 04/21/2022] [Indexed: 11/18/2022] Open
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18
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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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19
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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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Zia A, Farkhondeh T, Sahebdel F, Pourbagher-Shahri AM, Samarghandian S. Key miRNAs in Modulating Aging and Longevity: A Focus on Signaling Pathways and Cellular Targets. Curr Mol Pharmacol 2021; 15:736-762. [PMID: 34533452 DOI: 10.2174/1874467214666210917141541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 05/02/2021] [Accepted: 05/24/2021] [Indexed: 11/22/2022]
Abstract
Aging is a multifactorial procedure accompanied by gradual deterioration of most biological procedures of cells. MicroRNAs (miRNAs) are a class of short non-coding RNAs that post-transcriptionally regulate the expression of mRNAs through sequence-specific binding, and contributing to many crucial aspects of cell biology. Several miRNAs are expressed differently in various organisms through aging. The function of miRNAs in modulating aging procedures has been disclosed recently with the detection of miRNAs that modulate longevity in the invertebrate model organisms, through the IIS pathway. In these model organisms, several miRNAs have been detected to both negatively and positively regulate lifespan via commonly aging pathways. miRNAs modulate age-related procedures and disorders in different mammalian tissues by measuring their tissue-specific expression in older and younger counterparts, including heart, skin, bone, brain, and muscle tissues. Moreover, several miRNAs have been contributed to modulating senescence in different human cells, and the roles of these miRNAs in modulating cellular senescence have allowed illustrating some mechanisms of aging. The review discusses the available data on miRNAs through the aging process and we highlight the roles of miRNAs as aging biomarkers and regulators of longevity in cellular senescence, tissue aging, and organism lifespan.
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Affiliation(s)
- Aliabbas Zia
- Department of Biochemistry, Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran
| | - Tahereh Farkhondeh
- Cardiovascular Diseases Research Center, Birjand University of Medical Sciences, Birjand, Iran
| | - Faezeh Sahebdel
- Department of Rehabilitation Medicine, University of Minnesota Medical School, Minneapolis, MN, United States
| | | | - Saeed Samarghandian
- Noncommunicable Diseases Research Center, Neyshabur University of Medical Sciences, Neyshabur, Iran
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21
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Quan Y, Du Y, Tong Y, Gu S, Jiang JX. Connexin Gap Junctions and Hemichannels in Modulating Lens Redox Homeostasis and Oxidative Stress in Cataractogenesis. Antioxidants (Basel) 2021; 10:1374. [PMID: 34573006 PMCID: PMC8464761 DOI: 10.3390/antiox10091374] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 08/24/2021] [Indexed: 11/18/2022] Open
Abstract
The lens is continuously exposed to oxidative stress insults, such as ultraviolet radiation and other oxidative factors, during the aging process. The lens possesses powerful oxidative stress defense systems to maintain its redox homeostasis, one of which employs connexin channels. Connexins are a family of proteins that form: (1) Hemichannels that mediate the communication between the intracellular and extracellular environments, and (2) gap junction channels that mediate cell-cell communication between adjacent cells. The avascular lens transports nutrition and metabolites through an extensive network of connexin channels, which allows the passage of small molecules, including antioxidants and oxidized wastes. Oxidative stress-induced post-translational modifications of connexins, in turn, regulates gap junction and hemichannel permeability. Recent evidence suggests that dysfunction of connexins gap junction channels and hemichannels may induce cataract formation through impaired redox homeostasis. Here, we review the recent advances in the knowledge of connexin channels in lens redox homeostasis and their response to cataract-related oxidative stress by discussing two major aspects: (1) The role of lens connexins and channels in oxidative stress and cataractogenesis, and (2) the impact and underlying mechanism of oxidative stress in regulating connexin channels.
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Affiliation(s)
| | | | | | | | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA; (Y.Q.); (Y.D.); (Y.T.); (S.G.)
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22
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Retamal MA, Fernandez-Olivares A, Stehberg J. Over-activated hemichannels: A possible therapeutic target for human diseases. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166232. [PMID: 34363932 DOI: 10.1016/j.bbadis.2021.166232] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/21/2021] [Accepted: 07/26/2021] [Indexed: 12/14/2022]
Abstract
In our body, all the cells are constantly sharing chemical and electrical information with other cells. This intercellular communication allows them to respond in a concerted way to changes in the extracellular milieu. Connexins are transmembrane proteins that have the particularity of forming two types of channels; hemichannels and gap junction channels. Under normal conditions, hemichannels allow the controlled release of signaling molecules to the extracellular milieu. However, under certain pathological conditions, over-activated hemichannels can induce and/or exacerbate symptoms. In the last decade, great efforts have been put into developing new tools that can modulate these over-activated hemichannels. Small molecules, antibodies and mimetic peptides have shown a potential for the treatment of human diseases. In this review, we summarize recent findings in the field of hemichannel modulation via specific tools, and how these tools could improve patient outcome in certain pathological conditions.
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Affiliation(s)
- Mauricio A Retamal
- Universidad del Desarrollo, Programa de Comunicación Celular en Cáncer, Santiago, Chile; Universidad del Desarrollo, Centro de Fisiología Celular e Integrativa, Santiago, Chile.
| | | | - Jimmy Stehberg
- Laboratorio de Neurobiología, Instituto de Ciencias Biomédicas, Facultad de medicina y Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
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Astrocyte Networks as Therapeutic Targets in Glaucomatous Neurodegeneration. Cells 2021; 10:cells10061368. [PMID: 34199470 PMCID: PMC8228804 DOI: 10.3390/cells10061368] [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: 04/28/2021] [Revised: 05/28/2021] [Accepted: 05/30/2021] [Indexed: 11/22/2022] Open
Abstract
Astrocytes are intimately involved in the response to neurodegenerative stress and have become an attractive target for the development of neuroprotective therapies. However, studies often focus on astrocytes as single-cell units. Astrocytes are densely interconnected by gap junctions that are composed primarily of the protein connexin-43 (Cx43) and can function as a broader network of cells. Such networks contribute to a number of important processes, including metabolite distribution and extracellular ionic buffering, and are likely to play an important role in the progression of neurodegenerative disease. This review will focus on the pro-degenerative and pro-survival influence of astrocyte Cx43 in disease progression, with a focus on the roles of gap junctions and hemichannels in the spread of degenerative stress. Finally, we will highlight the specific evidence for targeting these networks in the treatment of glaucomatous neurodegeneration and other optic neuropathies.
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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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Van Campenhout R, Gomes AR, De Groof TW, Muyldermans S, Devoogdt N, Vinken M. Mechanisms Underlying Connexin Hemichannel Activation in Disease. Int J Mol Sci 2021; 22:ijms22073503. [PMID: 33800706 PMCID: PMC8036530 DOI: 10.3390/ijms22073503] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 03/22/2021] [Accepted: 03/26/2021] [Indexed: 02/07/2023] Open
Abstract
Gap junctions and connexin hemichannels mediate intercellular and extracellular communication, respectively. While gap junctions are seen as the “good guys” by controlling homeostasis, connexin hemichannels are considered as the “bad guys”, as their activation is associated with the onset and dissemination of disease. Open connexin hemichannels indeed mediate the transport of messengers between the cytosol and extracellular environment and, by doing so, fuel inflammation and cell death in a plethora of diseases. The present mini-review discusses the mechanisms involved in the activation of connexin hemichannels during pathology.
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Affiliation(s)
- Raf Van Campenhout
- Department of Pharmaceutical and Pharmacological Sciences, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium; (R.V.C.); (A.R.G.)
| | - Ana Rita Gomes
- Department of Pharmaceutical and Pharmacological Sciences, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium; (R.V.C.); (A.R.G.)
| | - Timo W.M. De Groof
- Department of Medical Imaging, In Vivo Cellular and Molecular Imaging Laboratory, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium; (T.W.M.D.G.); (N.D.)
| | - Serge Muyldermans
- Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium;
| | - Nick Devoogdt
- Department of Medical Imaging, In Vivo Cellular and Molecular Imaging Laboratory, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium; (T.W.M.D.G.); (N.D.)
| | - Mathieu Vinken
- Department of Pharmaceutical and Pharmacological Sciences, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium; (R.V.C.); (A.R.G.)
- Correspondence: ; Tel.: +32-2-4774587
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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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Harnessing the therapeutic potential of antibodies targeting connexin hemichannels. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166047. [PMID: 33418036 DOI: 10.1016/j.bbadis.2020.166047] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 11/17/2020] [Accepted: 12/03/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND Connexin hemichannels have been implicated in pathology-promoting conditions, including inflammation, numerous widespread human diseases, including cancer and diabetes, and several rare diseases linked to pathological point mutations. METHODS We analysed the literature focusing on antibodies capable of modulating hemichannel function, highlighting generation methods, applications to basic biomedical research and translational potential. RESULTS Anti-hemichannel antibodies generated over the past 3 decades targeted mostly connexin 43, with a focus on cancer treatment. A slow transition from relatively unselective polyclonal antibodies to more selective monoclonal antibodies resulted in few products with interesting characteristics that are under evaluation for clinical trials. Selection of antibodies from combinatorial phage-display libraries, has permitted to engineer a monoclonal antibody that binds to and blocks pathological hemichannels formed by connexin 26, 30 and 32. CONCLUSIONS All known antibodies that modulate connexin hemichannels target the two small extracellular loops of the connexin proteins. The extracellular region of different connexins is highly conserved, and few residues of each connexins are exposed. The search for new antibodies may develop an unprecedented potential for therapeutic applications, as it may benefit tremendously from novel whole-cell screening platforms that permit in situ selection of antibodies against membrane proteins in native state. The demonstrated efficacy of mAbs in reaching and modulating hemichannels in vivo, together with their relative specificity for connexins overlapping epitopes, should hopefully stimulate an interest for widening the scope of anti-hemichannel antibodies. There is no shortage of currently incurable diseases for which therapeutic intervention may benefit from anti-hemichannel antibodies capable of modulating hemichannel function selectively and specifically.
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Hu Z, Riquelme MA, Gu S, Jiang JX. Regulation of Connexin Gap Junctions and Hemichannels by Calcium and Calcium Binding Protein Calmodulin. Int J Mol Sci 2020; 21:E8194. [PMID: 33147690 PMCID: PMC7663298 DOI: 10.3390/ijms21218194] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 10/30/2020] [Accepted: 10/31/2020] [Indexed: 12/20/2022] Open
Abstract
Connexins are the structural components of gap junctions and hemichannels that mediate the communication and exchange of small molecules between cells, and between the intracellular and extracellular environment, respectively. Connexin (Cx) 46 is predominately expressed in lens fiber cells, where they function in maintaining the homeostasis and transparency of the lens. Cx46 mutations are associated with impairment of channel function, which results in the development of congenital cataracts. Cx46 gap junctions and hemichannels are closely regulated by multiple mechanisms. Key regulators of Cx46 channel function include Ca2+ and calmodulin (CaM). Ca2+ plays an essential role in lens homeostasis, and its dysregulation causes cataracts. Ca2+ associated CaM is a well-established inhibitor of gap junction coupling. Recent studies suggest that elevated intracellular Ca2+ activates Cx hemichannels in lens fiber cells and Cx46 directly interacts with CaM. A Cx46 site mutation (Cx46-G143R), which is associated with congenital Coppock cataracts, shows an increased Cx46-CaM interaction and this interaction is insensitive to Ca2+, given that depletion of Ca2+ reduces the interaction between CaM and wild-type Cx46. Moreover, inhibition of CaM function greatly reduces the hemichannel activity in the Cx46 G143R mutant. These research findings suggest a new regulatory mechanism by which enhanced association of Cx46 with CaM leads to the increase in hemichannel activity and dysregulation may lead to cataract development. In this review, we will first discuss the involvement of Ca2+/CaM in lens homeostasis and pathology, and follow by providing a general overview of Ca2+/CaM in the regulation of Cx46 gap junctions. We discuss the most recent studies concerning the molecular mechanism of Ca2+/CaM in regulating Cx46 hemichannels. Finally, we will offer perspectives of the impacts of Ca2+/CaM and dysregulation on Cx46 channels and vice versa.
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Affiliation(s)
- Zhengping Hu
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, MA 02114, USA;
- Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA
| | - Manuel A. Riquelme
- Departments of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA; (M.A.R.); (S.G.)
| | - Sumin Gu
- Departments of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA; (M.A.R.); (S.G.)
| | - Jean X. Jiang
- Departments of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA; (M.A.R.); (S.G.)
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Carina V, Della Bella E, Costa V, Bellavia D, Veronesi F, Cepollaro S, Fini M, Giavaresi G. Bone's Response to Mechanical Loading in Aging and Osteoporosis: Molecular Mechanisms. Calcif Tissue Int 2020; 107:301-318. [PMID: 32710266 DOI: 10.1007/s00223-020-00724-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/08/2020] [Indexed: 02/07/2023]
Abstract
Mechanotransduction is pivotal in the maintenance of homeostasis in different tissues and involves multiple cell signaling pathways. In bone, mechanical stimuli regulate the balance between bone formation and resorption; osteocytes play a central role in this regulation. Dysfunctions in mechanotransduction signaling or in osteocytes response lead to an imbalance in bone homeostasis. This alteration is very relevant in some conditions such as osteoporosis and aging. Both are characterized by increased bone weakness due to different causes, for example, the increase of osteocyte apoptosis that cause an alteration of fluid space, or the alteration of molecular pathways. There are intertwined yet very different mechanisms involved among the cell-intrinsic effects of aging on bone, the cell-intrinsic and tissue-level effects of estrogen/androgen withdrawal on bone, and the effects of reduced mechanical loading on bone, which are all involved to some degree in how aged bone fails to respond properly to stress/strain compared to younger bone. This review aims at clarifying how the cellular and molecular pathways regulated and induced in bone by mechanical stimulation are altered with aging and in osteoporosis, to highlight new possible targets for antiresorptive or anabolic bone therapeutic approaches.
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Affiliation(s)
- Valeria Carina
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy.
| | | | - Viviana Costa
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Daniele Bellavia
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Francesca Veronesi
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Simona Cepollaro
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Milena Fini
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
| | - Gianluca Giavaresi
- IRCCS Istituto Ortopedico Rizzoli, SC Scienze e Tecnologie Chirurgiche - SS Piattaforma Scienze Omiche per Ortopedia Personalizzata, Via Di Barbiano, 1/10, 40136, Bologna, Italy
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Brecker M, Khakhina S, Schubert TJ, Thompson Z, Rubenstein RC. The Probable, Possible, and Novel Functions of ERp29. Front Physiol 2020; 11:574339. [PMID: 33013490 PMCID: PMC7506106 DOI: 10.3389/fphys.2020.574339] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/14/2020] [Indexed: 12/16/2022] Open
Abstract
The luminal endoplasmic reticulum (ER) protein of 29 kDa (ERp29) is a ubiquitously expressed cellular agent with multiple critical roles. ERp29 regulates the biosynthesis and trafficking of several transmembrane and secretory proteins, including the cystic fibrosis transmembrane conductance regulator (CFTR), the epithelial sodium channel (ENaC), thyroglobulin, connexin 43 hemichannels, and proinsulin. ERp29 is hypothesized to promote ER to cis-Golgi cargo protein transport via COP II machinery through its interactions with the KDEL receptor; this interaction may facilitate the loading of ERp29 clients into COP II vesicles. ERp29 also plays a role in ER stress (ERS) and the unfolded protein response (UPR) and is implicated in oncogenesis. Here, we review the vast array of ERp29’s clients, its role as an ER to Golgi escort protein, and further suggest ERp29 as a potential target for therapies related to diseases of protein misfolding and mistrafficking.
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Affiliation(s)
- Margaret Brecker
- Cystic Fibrosis Center, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States
| | - Svetlana Khakhina
- Cystic Fibrosis Center, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States
| | - Tyler J. Schubert
- Cystic Fibrosis Center, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States
| | - Zachary Thompson
- Cystic Fibrosis Center, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States
| | - Ronald C. Rubenstein
- Cystic Fibrosis Center, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States
- Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
- Division of Allergy and Pulmonary Medicine, Department of Pediatrics, Washington University in St. Louis School of Medicine, St. Louis, MO, United States
- *Correspondence: Ronald C. Rubenstein, ;
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Osteocyte-Related Cytokines Regulate Osteoclast Formation and Bone Resorption. Int J Mol Sci 2020; 21:ijms21145169. [PMID: 32708317 PMCID: PMC7404053 DOI: 10.3390/ijms21145169] [Citation(s) in RCA: 169] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/16/2020] [Accepted: 07/20/2020] [Indexed: 01/18/2023] Open
Abstract
The process of bone remodeling is the result of the regulated balance between bone cell populations, namely bone-forming osteoblasts, bone-resorbing osteoclasts, and the osteocyte, the mechanosensory cell type. Osteoclasts derived from the hematopoietic stem cell lineage are the principal cells involved in bone resorption. In osteolytic diseases such as rheumatoid arthritis, periodontitis, and osteoporosis, the balance is lost and changes in favor of bone resorption. Therefore, it is vital to elucidate the mechanisms of osteoclast formation and bone resorption. It has been reported that osteocytes express Receptor activator of nuclear factor κΒ ligand (RANKL), an essential factor for osteoclast formation. RANKL secreted by osteocytes is the most important factor for physiologically supported osteoclast formation in the developing skeleton and in pathological bone resorption such as experimental periodontal bone loss. TNF-α directly enhances RANKL expression in osteocytes and promotes osteoclast formation. Moreover, TNF-α enhances sclerostin expression in osteocytes, which also increases osteoclast formation. These findings suggest that osteocyte-related cytokines act directly to enhance osteoclast formation and bone resorption. In this review, we outline the most recent knowledge concerning bone resorption-related cytokines and discuss the osteocyte as the master regulator of bone resorption and effector in osteoclast formation.
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Caufriez A, Böck D, Martin C, Ballet S, Vinken M. Peptide-based targeting of connexins and pannexins for therapeutic purposes. Expert Opin Drug Discov 2020; 15:1213-1222. [PMID: 32539572 DOI: 10.1080/17460441.2020.1773787] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
INTRODUCTION Connexin and pannexin (hemi)channels play an important role in paracrine and autocrine signaling pathways. The opening of these cellular pores is linked to a wide range of diseases. Therefore, pharmacological closing of connexin and pannexin (hemi)channels seems a promising therapeutic strategy. However, the currently available inhibitors cope with recurring problems concerning selectivity, specificity, stability and/or solubility. AREAS COVERED A number of peptides that mimic specific regions in the native sequence of connexins and pannexins have the potential to overcome some of these hurdles. In this paper, an overview is provided on these peptide-based inhibitors of connexin and pannexin (hemi)channels for therapeutic purposes. The authors also provide the reader with their expert perspectives on the future of these peptide-based inhibitors. EXPERT OPINION Peptide mimetics can become valuable tools in the treatment of connexin-related and pannexin-related diseases. This can be made possible provided that available peptides are optimized, and new peptide mimetics are designed based on knowledge of the mechanisms underlying the gating control of connexin and pannexin (hemi)channels.
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Affiliation(s)
- Anne Caufriez
- Department of in Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , 1090, Brussels, Belgium
| | - Denise Böck
- Department of in Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , 1090, Brussels, Belgium
| | - Charlotte Martin
- Department of Organic Chemistry, Vrije Universiteit Brussel , 1050, Brussels, Belgium
| | - Steven Ballet
- Department of Organic Chemistry, Vrije Universiteit Brussel , 1050, Brussels, Belgium
| | - Mathieu Vinken
- Department of in Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , 1090, Brussels, Belgium
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Vitamin E Blocks Connexin Hemichannels and Prevents Deleterious Effects of Glucocorticoid Treatment on Skeletal Muscles. Int J Mol Sci 2020; 21:ijms21114094. [PMID: 32521774 PMCID: PMC7312599 DOI: 10.3390/ijms21114094] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/03/2020] [Accepted: 06/04/2020] [Indexed: 01/06/2023] Open
Abstract
Glucocorticoids are frequently used as anti-inflammatory and immunosuppressive agents. However, high doses and/or prolonged use induce undesired secondary effects such as muscular atrophy. Recently, de novo expression of connexin43 and connexin45 hemichannels (Cx43 HCs and Cx45 HCs, respectively) has been proposed to play a critical role in the mechanism underlying myofiber atrophy induced by dexamethasone (Dex: a synthetic glucocorticoid), but their involvement in specific muscle changes promoted by Dex remains poorly understood. Moreover, treatments that could prevent the undesired effects of glucocorticoids on skeletal muscles remain unknown. In the present work, a 7-day Dex treatment in adult mice was found to induce weight loss and skeletal muscle changes including expression of functional Cx43/Cx45 HCs, elevated atrogin immunoreactivity, atrophy, oxidative stress and mitochondrial dysfunction. All these undesired effects were absent in muscles of mice simultaneously treated with Dex and vitamin E (VitE). Moreover, VitE was found to rapidly inhibit the activity of Cx HCs in freshly isolated myofibers of Dex treated mice. Exposure to alkaline pH induced free radical generation only in HeLa cells expressing Cx43 or Cx45 where Ca2+ was present in the extracellular milieu, response that was prevented by VitE. Besides, VitE and two other anti-oxidant compounds, Tempol and Resveratrol, were found to inhibit Cx43 HCs in HeLa cells transfectants. Thus, we propose that in addition to their intrinsic anti-oxidant potency, some antioxidants could be used to reduce expression and/or opening of Cx HCs and consequently reduce the undesired effect of glucocorticoids on skeletal muscles.
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Ramadan R, Vromans E, Anang DC, Goetschalckx I, Hoorelbeke D, Decrock E, Baatout S, Leybaert L, Aerts A. Connexin43 Hemichannel Targeting With TAT-Gap19 Alleviates Radiation-Induced Endothelial Cell Damage. Front Pharmacol 2020; 11:212. [PMID: 32210810 PMCID: PMC7066501 DOI: 10.3389/fphar.2020.00212] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/14/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Emerging evidence indicates an excess risk of late occurring cardiovascular diseases, especially atherosclerosis, after thoracic cancer radiotherapy. Ionizing radiation (IR) induces cellular effects which may induce endothelial cell dysfunction, an early marker for atherosclerosis. In addition, intercellular communication through channels composed of transmembrane connexin proteins (Cxs), i.e. Gap junctions (direct cell-cell coupling) and hemichannels (paracrine release/uptake pathway) can modulate radiation-induced responses and therefore the atherosclerotic process. However, the role of endothelial hemichannel in IR-induced atherosclerosis has never been described before. MATERIALS AND METHODS Telomerase-immortalized human Coronary Artery/Microvascular Endothelial cells (TICAE/TIME) were exposed to X-rays (0.1 and 5 Gy). Production of reactive oxygen species (ROS), DNA damage, cell death, inflammatory responses, and senescence were assessed with or without applying a Cx43 hemichannel blocker (TAT-Gap19). RESULTS We report here that IR induces an increase in oxidative stress, cell death, inflammatory responses (IL-8, IL-1β, VCAM-1, MCP-1, and Endothelin-1) and premature cellular senescence in TICAE and TIME cells. These effects are significantly reduced in the presence of the Cx43 hemichannel-targeting peptide TAT-Gap19. CONCLUSION Our findings suggest that endothelial Cx43 hemichannels contribute to various IR-induced processes, such as ROS, cell death, inflammation, and senescence, resulting in an increase in endothelial cell damage, which could be protected by blocking these hemichannels. Thus, targeting Cx43 hemichannels may potentially exert radioprotective effects.
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Affiliation(s)
- Raghda Ramadan
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK•CEN), Mol, Belgium
- Department of Fundamental and Basic Medical Sciences, Physiology Group, Ghent University, Ghent, Belgium
| | - Els Vromans
- Centre for Environmental Health Sciences, Hasselt University, Hasselt, Belgium
| | - Dornatien Chuo Anang
- Biomedical Research Institute and Transnational University of Limburg, Hasselt University, Hasselt, Belgium
| | - Ines Goetschalckx
- Protein Chemistry, Proteomics and Epigenetic Signaling Group, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Antwerp, Belgium
| | - Delphine Hoorelbeke
- Department of Fundamental and Basic Medical Sciences, Physiology Group, Ghent University, Ghent, Belgium
| | - Elke Decrock
- Department of Fundamental and Basic Medical Sciences, Physiology Group, Ghent University, Ghent, Belgium
| | - Sarah Baatout
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK•CEN), Mol, Belgium
- Department of Molecular Biotechnology, Ghent University, Ghent, Belgium
| | - Luc Leybaert
- Department of Fundamental and Basic Medical Sciences, Physiology Group, Ghent University, Ghent, Belgium
| | - An Aerts
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK•CEN), Mol, Belgium
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Ma JW, Ji DD, Li QQ, Zhang T, Luo L. Inhibition of connexin 43 attenuates oxidative stress and apoptosis in human umbilical vein endothelial cells. BMC Pulm Med 2020; 20:19. [PMID: 31964358 PMCID: PMC6975083 DOI: 10.1186/s12890-019-1036-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 12/19/2019] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Previous studies demonstrated an important role for connexin 43 (Cx43) in the regulation of apoptosis by influencing mitochondrial functions. This study aimed to investigate the relationship between Cx43 and lipopolysaccharide (LPS)-induced oxidative stress and apoptosis in human umbilical vein endothelial cells (HUVECs). METHODS Western blot was performed to determine mitochondrial Cx43 (MtCx43) protein level and phosphorylation (p-MtCx43). Gap19, a selective Cx43 inhibitor, was used to examine the effects of Cx43 on LPS-induced oxidative stress and apoptosis in HUVECs. Expression of regulatory genes associated with oxidative stress was examined by quantitative polymerase chain reaction (qPCR) and Western blot. Apoptosis was assessed by flow cytometry. RESULTS LPS stimulation resulted in increased levels of MtCx43 and p-MtCx43. Interestingly, Gap19 antagonized the upregulation of glutathione S-transferase Zeta 1 (GSTZ1) and cytochrome b alpha beta (CYBB), and the downregulation of antioxidant 1 (ATOX1), glutathione synthetase (GSS) and heme oxygenase 1 (HMOX1) induced by LPS or Cx43 overexpression. Moreover, the increased production of reactive oxygen species (ROS) and apoptosis elicited by LPS or Cx43 overexpression were reduced following treatment with Gap19. CONCLUSIONS Selective inhibition of Cx43 hemichannels protects HUVECs from LPS-induced apoptosis and this may be via a reduction in oxidative stress production.
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Affiliation(s)
- Jia-Wei Ma
- Department of Critical Care Medicine, The Affiliated Wuxi No.2 People's Hospital of Nanjing Medical University, Wuxi, 214002, China
| | - Dan-Dan Ji
- Department of Critical Care Medicine, The Affiliated Wuxi No.2 People's Hospital of Nanjing Medical University, Wuxi, 214002, China
| | - Qian-Qian Li
- Department of Critical Care Medicine, The Affiliated Wuxi No.2 People's Hospital of Nanjing Medical University, Wuxi, 214002, China
| | - Ting Zhang
- Department of Clinical Laboratory, The Affiliated Wuxi Matemity and Child Health Care Hospital of Nanjing Medical University, Wuxi, 214002, China.
| | - Liang Luo
- Department of Critical Care Medicine, The Affiliated Wuxi No.2 People's Hospital of Nanjing Medical University, Wuxi, 214002, China.
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Yang L, Zhou G, Li M, Li Y, Yang L, Fu Q, Tian Y. High Glucose Downregulates Connexin 43 Expression and Its Gap Junction and Hemichannel Function in Osteocyte-like MLO-Y4 Cells Through Activation of the p38MAPK/ERK Signal Pathway. Diabetes Metab Syndr Obes 2020; 13:545-557. [PMID: 32161481 PMCID: PMC7049751 DOI: 10.2147/dmso.s239892] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 02/16/2020] [Indexed: 12/30/2022] Open
Abstract
PURPOSE Osteocyte network structure correlates with bone material quality. This network is profoundly altered in diabetic mice; however, the underlying mechanisms are unknown. The gap junction protein connexin 43 (Cx43) is necessary for normal osteocyte function and osteocyte network formation. Here, we evaluated Cx43 expression in patients with diabetes, the effect of high glucose on Cx43 expression, and the function of Cx43 gap junctions and hemichannels in osteocyte-like MLO-Y4 (MLO-Y4) cells. PATIENTS AND METHODS Human cortical bone samples were obtained from patients with or without type II diabetes mellitus (T2DM) who underwent arthroplasty surgery to treat osteoporosis-induced femoral neck fracture. UNLABELLED Cx43 expression was quantified in human cortical bone samples from both groups of patients and MLO-Y4 cells. The functions of Cx43 gap junctions and hemichannels in MLO-Y4 cells were evaluated using dye transfer and dye uptake assays, respectively. Furthermore, we evaluated levels of membrane Cx43 (mCx43), the functional form, and p38MAPK/ERK1/2 signaling, which is involved in mCx43 internalization, to characterize the mechanism of decreased Cx43 expression and gap junctions and hemichannels function. RESULTS Osteocyte Cx43 expression was decreased in femoral neck cortical bone samples of patients with T2DM patients compared with the non-diabetic control group. In addition, Cx43 expression was decreased in MLO-Y4 cells treated with high glucose. The functions of Cx43 gap junctions and hemichannels were inhibited in MLO-Y4 cells treated with high glucose. mCx43 expression was decreased in response to activation of p38-MAPK/ERK signaling. Inhibition of the p38-MAPK/ERK pathway partially reversed the decreases in Cx43 hemichannels and gap-junctions function. CONCLUSION High glucose dampened Cx43 gap junction and hemichannel function in MLO-Y4 cells by activating the p38MAPK/ERK pathway leading to subsequent mCx43 internalization.
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Affiliation(s)
- Lei Yang
- Orthopedics Department, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, People’s Republic of China
| | - Guangping Zhou
- Orthopedics Department, Shenyang Orthopedics Hospital, Shenyang, Liaoning Province, People’s Republic of China
| | - Mingyang Li
- Orthopedics Department, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, People’s Republic of China
| | - Yan Li
- Orthopedics Department, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, People’s Republic of China
| | - Liqing Yang
- Orthopedics Department, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, People’s Republic of China
| | - Qin Fu
- Orthopedics Department, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, People’s Republic of China
- Correspondence: Qin Fu Tel +86-18940251086 Email
| | - Ye Tian
- Orthopedics Department, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, People’s Republic of China
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Abstract
Bone is the most frequent site of breast cancer and prostate cancer metastasis, and one of the most common sites of metastasis for many solid tumors. Once cancer cells colonize in the bone, it imposes a major clinical challenge for the treatment of the disease, and fatality rates increase drastically. Bone, the largest organ in the body, provides a fertile microenvironment enriched with nutrients, growth factors and hormones, a generous reward for cancer cells. Dependent on cancer type, cancer cells can cause osteoblastic (bone forming) or osteolytic lesions to promote the net resorption and/or release of growth factors from the bone extracellular matrix. These processes activate a "vicious cycle", leading to disruption of bone integrity and promoting cancer cell growth and migration. Cancer cells influence the bone microenvironment favoring their colonization and growth. In order to metastasize to the bone, cancer cells must first migrate from the site of origin, and once established within the bone, they must overcome the dormant inducing effects of resident cells. If successful, cancer cells can then colonize and continually disrupt bone homeostasis that is primarily maintained by osteocytes, the most abundant bone cell type. For example, it has been shown that exercise induces osteocytes to release anabolic factors that inhibit osteoclast resorptive activity, promote dormancy and the release of anti-cancer factors that inhibit breast cancer cell metastasis. In this review, we will summarize recent research findings and provide mechanistic insights related to the role of osteocytes in osteolytic metastasis.
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Werner SL, Sharma R, Woodruff K, Horn D, Harris SE, Gorin Y, Lee DY, Hua R, Gu S, Fajardo RJ, Habib SL, Jiang JX. CSF-1 in Osteocytes Inhibits Nox4-mediated Oxidative Stress and Promotes Normal Bone Homeostasis. JBMR Plus 2019; 4:e10080. [PMID: 32666016 DOI: 10.1002/jbm4.10080] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 08/28/2018] [Accepted: 08/30/2018] [Indexed: 12/12/2022] Open
Abstract
CSF-1 is a key factor in regulating bone remodeling; osteocytes express CSF-1 and its receptor. Viable osteocytes are essential for bone remodeling through cell-cell contact and secretion of factors that regulate osteoblasts and osteoclasts. Increased oxidative stress contributes to osteocyte death and correlates with bone loss during aging. The NADPH oxidase Nox4 is a major source of ROS in bone. CSF-1 decreases Nox4, suggesting that CSF-1 protects against oxidative stress. Here, we show that osteocyte apoptosis previously reported in our global CSF-1KO mice is associated with increased Nox4, as well as 4-HNE expression in osteocytes. Osteocytes isolated from CSF-1KO mice were less viable and showed increased intracellular ROS, elevated NADPH oxidase activity/Nox4 protein, activation of mTOR/S6K, and downstream apoptosis signals compared with WT osteocytes. Nox4 expression was also increased in CSF-1KO osteocytes and colocalized with MitoTracker Red in mitochondria. Notably, CSF-1 inhibited Nox4 expression and apoptosis cascade signals. In additional studies, shNox4 decreased these signals in CSF-1KO osteocytes, whereas overexpression of Nox4 in WT osteocytes activated the apoptosis pathway. To determine the role of CSF-1 in osteocytes, DMP1Cre-CSF-1cKO (CSF-1cKO) mice that lack CSF-1 in osteocytes/late osteoblasts were developed. Osteocyte defects in CSF-1cKO mice overlapped with those in CSF-1KO mice, including increased apoptosis, Nox4, and 4-HNE-expressing osteocytes. CSF-1cKO mice showed unbalanced cancellous bone remodeling with decreased bone formation and resorption. Continued exposure to high Nox4/ROS levels may further compromise bone formation and predispose to bone loss and skeletal fragility. Taken together, our findings suggest a novel link between CSF-1, Nox4-derived ROS, and osteocyte survival/function that is crucial for osteocyte-mediated bone remodeling. Results reveal new mechanisms by which CSF-1/oxidative stress regulate osteocyte homeostasis, which may lead to therapeutic strategies to improve skeletal health in aging. © 2018 American Society for Bone and Mineral Research.
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Affiliation(s)
- Sherry L Werner
- Department of Pathology University of Texas Health Science Center at San Antonio TX USA
| | - Ramaswamy Sharma
- Department of Cell Systems and Anatomy University of Texas Health Science Center at San Antonio TX USA
| | - Kathleen Woodruff
- Department of Pathology University of Texas Health Science Center at San Antonio TX USA
| | - Diane Horn
- Department of Pathology University of Texas Health Science Center at San Antonio TX USA
| | - Stephen E Harris
- Department of Periodontics University of Texas Health Science Center at San Antonio TX USA
| | - Yves Gorin
- Department of Medicine/Nephrology University of Texas Health Science Center at San Antonio TX USA
| | - Doug-Yoon Lee
- Department of Medicine/Nephrology University of Texas Health Science Center at San Antonio TX USA
| | - Rui Hua
- Department of Biochemistry and Structural Biology University of Texas Health Science Center at San Antonio TX USA
| | - Sumin Gu
- Department of Biochemistry and Structural Biology University of Texas Health Science Center at San Antonio TX USA
| | - Roberto J Fajardo
- Department of Orthopedics University of Texas Health Science Center at San Antonio TX USA
| | - Samy L Habib
- South Texas Veterans Health Care and Department of Cell Systems and Anatomy University of Texas Health Science Center at San Antonio TX USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology University of Texas Health Science Center at San Antonio TX USA
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Abstract
PURPOSE OF REVIEW An elevated level of pro-inflammatory cytokines in inflammatory conditions causes bone loss and disrupts vital organ function. Osteocytes comprise > 95% of the cellular component in bone tissue, produce a range of cytokines and signaling molecules, and influence bone and other organ function. In this review, we hypothesized that an elevated level of pro-inflammatory cytokines in inflammatory conditions affects osteocyte survival and function thereby possibly amplifying inflammation, and causing bone loss and non-bone clinical complications. RECENT FINDINGS Several studies have reported that the elevated level of pro-inflammatory cytokines in inflammatory conditions alters osteocyte mechanosensitivity, causes osteocyte apoptosis, and modulates osteocyte-derived production of various inflammatory cytokines and signaling molecules. Cytokines and signaling molecules released from osteocytes affect surrounding bone cells and distant organ function in a paracrine and endocrine fashion. Inflammatory diseases including diabetes, chronic kidney disease, rheumatoid arthritis, and periodontitis affect osteocyte survival and function, and upregulate osteocyte-derived expression of sclerostin, RANKL, TNFα, FGF23, DKK1, and other signaling molecules.
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Affiliation(s)
- Miao Zhou
- Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Affiliated Stomatology Hospital of Guangzhou Medical University, Huangsha Avenue 39, Guangzhou, 510140, China
| | - Shuyi Li
- Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Affiliated Stomatology Hospital of Guangzhou Medical University, Huangsha Avenue 39, Guangzhou, 510140, China
| | - Janak L Pathak
- Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Affiliated Stomatology Hospital of Guangzhou Medical University, Huangsha Avenue 39, Guangzhou, 510140, China.
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CGRP signalling inhibits NO production through pannexin-1 channel activation in endothelial cells. Sci Rep 2019; 9:7932. [PMID: 31138827 PMCID: PMC6538758 DOI: 10.1038/s41598-019-44333-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/13/2019] [Indexed: 02/07/2023] Open
Abstract
Blood flow distribution relies on precise coordinated control of vasomotor tone of resistance arteries by complex signalling interactions between perivascular nerves and endothelial cells. Sympathetic nerves are vasoconstrictors, whereas endothelium-dependent NO production provides a vasodilator component. In addition, resistance vessels are also innervated by sensory nerves, which are activated during inflammation and cause vasodilation by the release of calcitonin gene-related peptide (CGRP). Inflammation leads to superoxide anion (O2• -) formation and endothelial dysfunction, but the involvement of CGRP in this process has not been evaluated. Here we show a novel mechanistic relation between perivascular sensory nerve-derived CGRP and the development of endothelial dysfunction. CGRP receptor stimulation leads to pannexin-1-formed channel opening and the subsequent O2• --dependent connexin-based hemichannel activation in endothelial cells. The prolonged opening of these channels results in a progressive inhibition of NO production. These findings provide new therapeutic targets for the treatment of the inflammation-initiated endothelial dysfunction.
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Connexin 43 hemichannels protect bone loss during estrogen deficiency. Bone Res 2019; 7:11. [PMID: 31016065 PMCID: PMC6476886 DOI: 10.1038/s41413-019-0050-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 02/28/2019] [Accepted: 03/18/2019] [Indexed: 02/02/2023] Open
Abstract
Estrogen deficiency in postmenopausal women is a major cause of bone loss, resulting in osteopenia, osteoporosis, and a high risk for bone fracture. Connexin 43 (Cx43) hemichannels (HCs) in osteocytes play an important role in osteocyte viability, bone formation, and remodeling. We showed here that estrogen deficiency reduced Cx43 expression and HC function. To determine if functional HCs protect osteocytes and bone loss during estrogen deficiency, we adopted an ovariectomy model in wild-type (WT) and two transgenic Cx43 mice: R76W (dominant-negative mutant inhibiting only gap junction channels) and Cx43 Δ130–136 (dominant-negative mutant compromising both gap junction channels and HCs). The bone mineral density (BMD), bone structure, and histomorphometric changes of cortical and trabecular bones after ovariectomy were investigated. Our results showed that the Δ130–136 transgenic cohort had greatly decreased vertebral trabecular bone mass compared to WT and R76W mice, associated with a significant increase in the number of apoptotic osteocyte and empty lacunae. Moreover, osteoclast surfaces in trabecular and cortical bones were increased after ovariectomy in the R76W and WT mice, respectively, but not in ∆130–136 mice. These data demonstrate that impairment of Cx43 HCs in osteocytes accelerates vertebral trabecular bone loss and increase in osteocyte apoptosis, and further suggest that Cx43 HCs in osteocytes protect trabecular bone against catabolic effects due to estrogen deficiency. Channels that form between cells and their extracellular environment help protect bone tissue from the damage wrought by low estrogen levels, a major cause of bone loss in post-menopausal women. Jean Jiang from the UT Health San Antonio and colleagues showed that depleting the estrogen hormone in mouse bone cells reduced levels of connexin 43 and impaired the protein’s ability to forms pores known as ‘hemichannels’. The researchers surgically removed the ovaries of various mouse strains to induce estrogen deficiencies. They found that transgenic mice without working hemichannels had reduced bone mass compared to normal mice or mice that could make hemichannels but lacked the ability for those channels to come together to form complete passageways. The findings highlight the importance of connexin 43 hemichannels in protecting bone tissue against osteoporosis.
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42
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Kar R, Riquelme MA, Hua R, Jiang JX. Glucocorticoid-Induced Autophagy Protects Osteocytes Against Oxidative Stress Through Activation of MAPK/ERK Signaling. JBMR Plus 2018; 3:e10077. [PMID: 31044179 PMCID: PMC6478584 DOI: 10.1002/jbm4.10077] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 08/13/2018] [Accepted: 08/19/2018] [Indexed: 12/19/2022] Open
Abstract
Autophagy confers protective or detrimental effects on cells depending on the cellular context. We showed here that oxidative stress‐induced cell death in osteocytic MLO‐Y4 cells coincided with decreased autophagy. Decreased autophagy was also observed in osteocytes of superoxide dismutase 1‐ (SOD1‐) deficient mice. Oxidative stress‐induced osteocyte death was exacerbated by an autophagy inhibitor, chloroquine, suggesting a protective function of basal autophagy levels against oxidative stress‐induced cell death. Pretreatment with dexamethasone reduced the susceptibility of osteocytes to oxidative stress‐induced cell death and conferred protection against TNFα/cycloheximide‐induced cell death. Inhibition of MAPK/ERK attenuated the formation of autophagosome, leading to increased osteocyte cell death. Taken together, our results suggest that autophagy, induced by moderate levels of glucocorticoids, leads to the preconditioning of osteocytes and conveys a novel cell‐protective function against cell death induced by oxidative stress and other insults. © 2018 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.
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Affiliation(s)
- Rekha Kar
- 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
| | - Rui Hua
- 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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Zhou Z, Lu Y, Wang Y, Du L, Zhang Y, Tao J. Let-7c regulates proliferation and osteodifferentiation of human adipose-derived mesenchymal stem cells under oxidative stress by targeting SCD-1. Am J Physiol Cell Physiol 2018; 316:C57-C69. [PMID: 30379578 DOI: 10.1152/ajpcell.00211.2018] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Osteoporosis is a progressive bone disease characterized by decreased bone mass and density, which usually parallels a reduced antioxidative capacity and increased reactive oxygen species formation. Adipose-derived mesenchymal stem cells (ADMSCs), a population of self-renewing multipotent cells, are a well-recognized source of potential bone precursors with significant clinical potential for tissue regeneration. We previously showed that overexpressing stearoyl-CoA desaturase 1 (SCD-1) promotes osteogenic differentiation of mesenchymal stem cells. Micro-RNAs (miRNAs) are noncoding RNAs recently recognized to play key roles in many developmental processes, and miRNA let-7c is downregulated during osteoinduction. We found that let-7c was upregulated in the serum of patients with postmenopausal osteoporosis compared with healthy controls. Levels of let-7c during osteogenic differentiation of ADMSCs were examined under oxidative stress in vitro and found to be upregulated. Overexpression of let-7c inhibited osteogenic differentiation, whereas inhibition of let-7c function promoted this process, evidenced by increased expression of osteoblast-specific genes, alkaline phosphatase activity, and matrix mineralization. The luciferase reporter assay was used to validate SCD-1 as a target of let-7c. Further experiments showed that silencing of SCD-1 significantly attenuated the effect of let-7c inhibitor on osteoblast markers, providing strong evidence that let-7c modulates osteogenic differentiation by targeting SCD-1. Inhibition of let-7c promoted the translocation of β-catenin into nuclei, thus activating Wnt/β-catenin signaling. Collectively, these data suggest that let-7c is induced under oxidative stress conditions and in osteoporosis, reducing SCD-1 protein levels, switching off Wnt/β-catenin signaling, and inhibiting osteogenic differentiation. Thus, let-7c may be a potential therapeutic target in the treatment of osteoporosis and especially postmenopausal osteoporosis.
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Affiliation(s)
- Zihui Zhou
- Department of Orthopedics, Shanghai General Hospital, Shanghai Jiao Tong University , Shanghai , China
| | - Yuanshan Lu
- Department of Blood Transfusion, Shanghai General Hospital, Shanghai Jiao Tong University , Shanghai , China
| | - Yao Wang
- Department of Orthopedics, Shanghai General Hospital, Shanghai Jiao Tong University , Shanghai , China
| | - Lin Du
- Department of Orthopedics, Shanghai General Hospital, Shanghai Jiao Tong University , Shanghai , China
| | - Yunpeng Zhang
- Department of Orthopedics, Shanghai General Hospital, Shanghai Jiao Tong University , Shanghai , China
| | - Jie Tao
- Department of Orthopedics, Shanghai General Hospital, Shanghai Jiao Tong University , Shanghai , China
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Carpintero-Fernandez P, Gago-Fuentes R, Wang HZ, Fonseca E, Caeiro JR, Valiunas V, Brink PR, Mayan MD. Intercellular communication via gap junction channels between chondrocytes and bone cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2499-2505. [PMID: 30279151 DOI: 10.1016/j.bbamem.2018.09.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 08/06/2018] [Accepted: 09/12/2018] [Indexed: 02/07/2023]
Abstract
Cell-to-cell communication between bone, cartilage and the synovial membrane is not fully understood and it is only attributed to the diffusion of substances through the extracellular space or synovial fluid. In this study, we found for the first time that primary bone cells (BCs) including osteocytes, synovial cells (SCs) and chondrocytes (CHs) are able to establish cellular contacts and to couple through gap junction (GJ) channels with connexin43 (Cx43) being dominant. Transwell co-culture and identification by mass spectrometry revealed the exchange of essential amino acids, peptides and proteins including calnexin, calreticulin or CD44 antigen between contacting SCs, BCs and CHs. These results reveal that CHs, SCs and BCs are able to establish intercellular connections and to communicate through GJ channels, which provide a selective signalling route by the direct exchange of potent signalling molecules and metabolites.
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Affiliation(s)
- Paula Carpintero-Fernandez
- CellCOM-SB Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), University of A Coruña, Servizo Galego de Saúde (SERGAS), Xubias de Arriba, 84 15006 A Coruña, Spain; Epigenetic and Cellular Senescence Group, Blizard Institute, Queen Mary University of London, 4 Newark Street, London E1 2AT, UK
| | - Raquel Gago-Fuentes
- CellCOM-SB Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), University of A Coruña, Servizo Galego de Saúde (SERGAS), Xubias de Arriba, 84 15006 A Coruña, Spain
| | - Hong Z Wang
- Department of Physiology and Biophysics, State University of New York, Stony Brook, New York, USA
| | - Eduardo Fonseca
- CellCOM-SB Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), University of A Coruña, Servizo Galego de Saúde (SERGAS), Xubias de Arriba, 84 15006 A Coruña, Spain
| | - José R Caeiro
- Department of Orthopaedic Surgery and Traumatology, Complexo Hospitalario Universitario de Santiago de Compostela, Universidade de Santiago de Compostela (USC), Choupana s/n, 15706 Santiago de Compostela, Spain
| | - Virginijus Valiunas
- Department of Physiology and Biophysics, State University of New York, Stony Brook, New York, USA
| | - Peter R Brink
- Department of Physiology and Biophysics, State University of New York, Stony Brook, New York, USA
| | - Maria D Mayan
- CellCOM-SB Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), University of A Coruña, Servizo Galego de Saúde (SERGAS), Xubias de Arriba, 84 15006 A Coruña, Spain.
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45
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Connexin 43 regulates the expression of wound healing-related genes in human gingival and skin fibroblasts. Exp Cell Res 2018; 367:150-161. [PMID: 29596891 DOI: 10.1016/j.yexcr.2018.03.031] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/23/2018] [Accepted: 03/24/2018] [Indexed: 12/21/2022]
Abstract
Fibroblasts are the most abundant connective tissue cells and play an important role in wound healing. It is possible that faster and scarless wound healing in oral mucosal gingiva relative to skin may relate to the distinct phenotype of the fibroblasts residing in these tissues. Connexin 43 (Cx43) is the most ubiquitous Cx in skin (SFBLs) and gingival fibroblasts (GFBLs), and assembles into hemichannels (HCs) and gap junctions (GJs) on the cell membrane. We hypothesized that SFBLs and GFBLs display distinct expression or function of Cx43, and that this may partly underlie the different wound healing outcomes in skin and gingiva. Here we show that Cx43 distinctly formed Cx43 GJs and HCs in human skin and gingiva in vivo. However, in SFBLs, in contrast to GFBLs, only a small proportion of total Cx43 assembled into HC plaques. Using an in vivo-like 3D culture model, we further show that the GJ, HC, and channel-independent functions of Cx43 distinctly regulated wound healing-related gene expression in GFBLs and SFBLs. Therefore, the distinct wound healing outcomes in skin and gingiva may partly relate to the inherently different assembly and function of Cx43 in the resident fibroblasts.
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Shi W, Riquelme MA, Gu S, Jiang JX. Connexin hemichannels mediate glutathione transport and protect lens fiber cells from oxidative stress. J Cell Sci 2018; 131:jcs212506. [PMID: 29487175 PMCID: PMC5897712 DOI: 10.1242/jcs.212506] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 02/07/2018] [Indexed: 01/04/2023] Open
Abstract
Elevated oxidized stress contributes to lens cataracts, and gap junctions play important roles in maintaining lens transparency. As well as forming gap junctions, connexin (Cx) proteins also form hemichannels. Here, we report a new mechanism whereby hemichannels mediate transport of reductant glutathione into lens fiber cells and protect cells against oxidative stress. We found that Cx50 (also known as GJA8) hemichannels opened in response to H2O2 in lens fiber cells but that transport through the channels was inhibited by two dominant-negative mutants in Cx50, Cx50P88S, which inhibits transport through both gap junctions and hemichannels, and Cx50H156N, which only inhibits transport through hemichannels and not gap junctions. Treatment with H2O2 increased the number of fiber cells undergoing apoptosis, and this increase was augmented with dominant-negative mutants that disrupted both hemichannels formed from Cx46 (also known as GJA3) and Cx50, while Cx50E48K, which only impairs gap junctions, did not have such an effect. Moreover, hemichannels mediate uptake of glutathione, and this uptake protected lens fiber cells against oxidative stress, while hemichannels with impaired transport had less protective benefit from glutathione. Taken together, these results show that oxidative stress activates connexin hemichannels in the lens fiber cells and that hemichannels likely protect lens cell against oxidative damage through transporting extracellular reductants.
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Affiliation(s)
- Wen Shi
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha 410000, China
| | - Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
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Abstract
Although a plethora of signaling pathways are known to drive the activation of hepatic stellate cells in liver fibrosis, the involvement of connexin-based communication in this process remains elusive. Connexin43 expression is enhanced in activated hepatic stellate cells and constitutes the molecular building stone of hemichannels and gap junctions. While gap junctions support intercellular communication, and hence the maintenance of liver homeostasis, hemichannels provide a circuit for extracellular communication and are typically opened by pathological stimuli, such as oxidative stress and inflammation. The present study was set up to investigate the effects of inhibition of connexin43-based hemichannels and gap junctions on liver fibrosis in mice. Liver fibrosis was induced by administration of thioacetamide to Balb/c mice for eight weeks. Thereafter, mice were treated for two weeks with TAT-Gap19, a specific connexin43 hemichannel inhibitor, or carbenoxolone, a general hemichannel and gap junction inhibitor. Subsequently, histopathological analysis was performed and markers of hepatic damage and functionality, oxidative stress, hepatic stellate cell activation and inflammation were evaluated. Connexin43 hemichannel specificity of TAT-Gap19 was confirmed in vitro by fluorescence recovery after photobleaching analysis and the measurement of extracellular release of adenosine-5′-triphosphate. Upon administration to animals, both TAT-Gap19 and carbenoxolone lowered the degree of liver fibrosis accompanied by superoxide dismutase overactivation and reduced production of inflammatory proteins, respectively. These results support a role of connexin-based signaling in the resolution of liver fibrosis, and simultaneously demonstrate the therapeutic potential of TAT-Gap19 and carbenoxolone in the treatment of this type of chronic liver disease.
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48
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Qin Y, Han L, Yang D, Wei H, Liu Y, Xu J, Autrup H, Deng F, Guo X. Silver nanoparticles increase connexin43-mediated gap junctional intercellular communication in HaCaT cells through activation of reactive oxygen species and mitogen-activated protein kinase signal pathway. J Appl Toxicol 2017; 38:564-574. [PMID: 29235124 DOI: 10.1002/jat.3563] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 10/01/2017] [Accepted: 10/10/2017] [Indexed: 01/17/2023]
Abstract
Silver nanoparticles (AgNPs) are widely used in health and consumer products that routinely contact skin. However, the biological effects and possible mechanisms of AgNPs on skin remain unclear. Gap junctional intercellular communication (GJIC) plays a critical role in multicellular organisms to maintain tissue homeostasis. The aim of this study is to examine if non-coated AgNPs affect GJIC in human keratinocytes (HaCaT cells), and to identify the possible molecular mechanisms responsible for the effects. GJIC, connexin (Cx)43 protein and mRNA expression, and the effect of siRNA-mediated knockdown of Cx43 on GJIC were assessed. HaCaT cells exposed to non-coated AgNPs at different doses after a 24 hour exposure. To explore further the underlying mechanism, reactive oxygen species and mitogen-activated protein kinase pathway were evaluated after 2, 6, 12 and 24 hours. Our results revealed that non-coated AgNP exposure at subcytotoxic doses increase GJIC partially via Cx43 upregulation. Reactive oxygen species and extracellular signal-regulated kinase and activation of c-Jun N-terminal kinase were involved in the AgNP-induced upregulation of Cx43. This study provides new insight into the potential mechanism of AgNP biological activity.
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Affiliation(s)
- Yu Qin
- Department of Occupational and Environmental Health Sciences, Peking University School of Public Health, Beijing, China
| | - Limin Han
- Department of Biochemistry and Molecular Biology, Peking University School of Basic Medical Sciences, Beijing, China
| | - Di Yang
- Department of Occupational and Environmental Health Sciences, Peking University School of Public Health, Beijing, China
| | - Hongying Wei
- Department of Occupational and Environmental Health Sciences, Peking University School of Public Health, Beijing, China
| | - Yue Liu
- Department of Occupational and Environmental Health Sciences, Peking University School of Public Health, Beijing, China
| | - Junhui Xu
- Department of Occupational and Environmental Health Sciences, Peking University School of Public Health, Beijing, China
| | - Herman Autrup
- Department of Environmental and Occupational Medicine, Aarhus University Institute of Public Health, Aarhus, Denmark
| | - Furong Deng
- Department of Occupational and Environmental Health Sciences, Peking University School of Public Health, Beijing, China
| | - Xinbiao Guo
- Department of Occupational and Environmental Health Sciences, Peking University School of Public Health, Beijing, China
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Willebrords J, Maes M, Crespo Yanguas S, Vinken M. Inhibitors of connexin and pannexin channels as potential therapeutics. Pharmacol Ther 2017; 180:144-160. [PMID: 28720428 PMCID: PMC5802387 DOI: 10.1016/j.pharmthera.2017.07.001] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
While gap junctions support the exchange of a number of molecules between neighboring cells, connexin hemichannels provide communication between the cytosol and the extracellular environment of an individual cell. The latter equally holds true for channels composed of pannexin proteins, which display an architecture reminiscent of connexin hemichannels. In physiological conditions, gap junctions are usually open, while connexin hemichannels and, to a lesser extent, pannexin channels are typically closed, yet they can be activated by a number of pathological triggers. Several agents are available to inhibit channels built up by connexin and pannexin proteins, including alcoholic substances, glycyrrhetinic acid, anesthetics and fatty acids. These compounds not always strictly distinguish between gap junctions, connexin hemichannels and pannexin channels, and may have effects on other targets as well. An exception lies with mimetic peptides, which reproduce specific amino acid sequences in connexin or pannexin primary protein structure. In this paper, a state-of-the-art overview is provided on inhibitors of cellular channels consisting of connexins and pannexins with specific focus on their mode-of-action and therapeutic potential.
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Affiliation(s)
- Joost Willebrords
- Department of In Vitro Toxicology and Dermato-cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium
| | - Michaël Maes
- Department of In Vitro Toxicology and Dermato-cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium
| | - Sara Crespo Yanguas
- Department of In Vitro Toxicology and Dermato-cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium.
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50
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Shaito A, Saliba J, Husari A, El-Harakeh M, Chhouri H, Hashem Y, Shihadeh A, El-Sabban M. Electronic Cigarette Smoke Impairs Normal Mesenchymal Stem Cell Differentiation. Sci Rep 2017; 7:14281. [PMID: 29079789 PMCID: PMC5660168 DOI: 10.1038/s41598-017-14634-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 10/05/2017] [Indexed: 12/13/2022] Open
Abstract
Electronic cigarettes (e-cigarettes) are promoted as low-risk alternatives to combustible cigarettes. However, the effects of chronic inhalation of potential toxicants emitted by ecigarettes remain largely unexamined. It is conceivable that smoking-induced chronic diseases result in cellular injury, in the absence of effective repair by stem cells. This study evaluates the effect of cigarette and e-cigarette aerosol extracts on the survival and differentiation of bone marrow-derived mesenchymal stem cells (MSCs). MSC growth and osteogenic differentiation were examined after exposure to smoke extracts. Data revealed detrimental effects of both cigarette and e-cigarette extracts on MSC morphology and growth. Levels and activity of alkaline phosphatase, an osteogenic marker, decreased and induction of osteoblastic differentiation was impaired. Both smoke extracts prevented osteogenic differentiation from progressing, evident by decreased expression of terminal osteogenic markers and mineralization. Elevated levels of reactive oxygen species (ROS) were detected in cells exposed to smoke extracts. Moreover, decreased differentiation potential was concomitant with severe down-regulation of Connexin 43 expression, leading to the loss of gap junction-mediated communication, which together with elevated ROS levels, could explain decreased proliferation and loss of differentiation potential. Hence, e-cigarettes present similar risk as combustible cigarettes with respect to tissue repair impairment.
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Affiliation(s)
- A Shaito
- Department of Biological and Chemical Sciences, Faculty of Arts and Sciences, Lebanese International University, Beirut, Lebanon
| | - J Saliba
- Department of Biology, Faculty of Science, Lebanese University, Beirut, Lebanon
| | - A Husari
- Department of Internal Medicine, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - M El-Harakeh
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - H Chhouri
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Y Hashem
- Department of Internal Medicine, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - A Shihadeh
- Department of Mechanical Engineering, Faculty of Engineering, American University of Beirut, Beirut, Lebanon
| | - M El-Sabban
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.
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