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Abstract
Gap junctions, comprising connexin proteins, create conduits directly coupling the cytoplasms of adjacent cells. Expressed in essentially all tissues, dynamic gap junction structures enable the exchange of small molecules including ions and second messengers, and are central to maintenance of homeostasis and synchronized excitability. With such diverse and critical roles throughout the body, it is unsurprising that alterations to gap junction and/or connexin expression and function underlie a broad array of age-related pathologies. From neurological dysfunction to cardiac arrhythmia and bone loss, it is hard to identify a human disease state that does not involve reduced, or in some cases inappropriate, intercellular communication to affect organ function. With a complex life cycle encompassing several key regulatory steps, pathological gap junction remodeling during ageing can arise from alterations in gene expression, translation, intracellular trafficking, and posttranslational modification of connexins. Connexin proteins are now known to "moonlight" and perform a variety of non-junctional functions in the cell, independent of gap junctions. Furthermore, connexin "hemichannels" on the cell surface can communicate with the extracellular space without ever coupling to an adjacent cell to form a gap junction channel. This chapter will focus primarily on gap junctions in ageing, but such non-junctional connexin functions will be referred to where appropriate and the full spectrum of connexin biology should be noted as potentially causative/contributing to some findings in connexin knockout animals, for example.
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Affiliation(s)
- Michael J Zeitz
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, USA.,FBRI Center for Vascular and Heart Research, Roanoke, VA, USA
| | - James W Smyth
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, USA. .,FBRI Center for Vascular and Heart Research, Roanoke, VA, USA. .,Department of Biological Sciences, College of Science, Virginia Tech, Blacksburg, VA, USA. .,Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, VA, USA.
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2
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Shojaei Baghini S, Gardanova ZR, Zekiy AO, Shomali N, Tosan F, Jarahian M. Optimizing sgRNA to Improve CRISPR/Cas9 Knockout Efficiency: Special Focus on Human and Animal Cell. Front Bioeng Biotechnol 2021; 9:775309. [PMID: 34869290 PMCID: PMC8640246 DOI: 10.3389/fbioe.2021.775309] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/26/2021] [Indexed: 12/26/2022] Open
Abstract
During recent years, clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) technologies have been noticed as a rapidly evolving tool to deliver a possibility for modifying target sequence expression and function. The CRISPR/Cas9 tool is currently being used to treat a myriad of human disorders, ranging from genetic diseases and infections to cancers. Preliminary reports have shown that CRISPR technology could result in valued consequences for the treatment of Duchenne muscular dystrophy (DMD), cystic fibrosis (CF), β-thalassemia, Huntington's diseases (HD), etc. Nonetheless, high rates of off-target effects may hinder its application in clinics. Thereby, recent studies have focused on the finding of the novel strategies to ameliorate these off-target effects and thereby lead to a high rate of fidelity and accuracy in human, animals, prokaryotes, and also plants. Meanwhile, there is clear evidence indicating that the design of the specific sgRNA with high efficiency is of paramount importance. Correspondingly, elucidation of the principal parameters that contributed to determining the sgRNA efficiencies is a prerequisite. Herein, we will deliver an overview regarding the therapeutic application of CRISPR technology to treat human disorders. More importantly, we will discuss the potent influential parameters (e.g., sgRNA structure and feature) implicated in affecting the sgRNA efficacy in CRISPR/Cas9 technology, with special concentration on human and animal studies.
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Affiliation(s)
- Sadegh Shojaei Baghini
- Plant Biotechnology Department, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
| | - Zhanna R. Gardanova
- Department of Psychotherapy, Pirogov Russian National Research Medical University, Moscow, Russia
- Medical Faculty, Russian State Social University, Moscow, Russia
| | - Angelina Olegovna Zekiy
- Department of Prosthetic Dentistry, I. M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | - Navid Shomali
- Immunology Research Center (IRC), Tabriz University of Medical Sciences, Tabriz, Iran
| | - Foad Tosan
- Student Research Committee, Semnan University of Medical Sciences, Semnan, Iran
| | - Mostafa Jarahian
- German Cancer Research Center, Toxicology and Chemotherapy Unit (G401), Heidelberg, Germany
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3
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Trosko JE. In Search of a Unifying Concept in Human Diseases. Diseases 2021; 9:68. [PMID: 34698126 PMCID: PMC8544458 DOI: 10.3390/diseases9040068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 09/29/2021] [Accepted: 09/30/2021] [Indexed: 02/06/2023] Open
Abstract
Throughout the history of biological/medicine sciences, there has been opposing strategies to find solutions to complex human disease problems. Both empirical and deductive approaches have led to major insights and concepts that have led to practical preventive and therapeutic benefits for the human population. The classic definitions of "science" (to know) has been paired with the classic definition of technology (to do). One knew more as the technology developed, and that development was often based on science. In other words, one could do more if science could improve the technology. In turn, this made possible to know more science with improved technology. However, with the development of new technologies of today in biology and medicine, major advances have been made, such as the information from the Human Genome Project, genetic engineering techniques and the use of bioinformatic uses of sophisticated computer analyses. This has led to the renewed idea that Precision Medicine, while raising some serious ethical concerns, also raises the expectation of improved potential of risk predictions for prevention and treatment of various genetically and environmentally influenced human diseases. This new field Artificial Intelligence, as a major handmaiden to Precision Medicine, is significantly altering the fundamental means of biological discovery. However, can today's fundamental premise of "Artificial Intelligence", based on identifying DNA, as the primary nexus of human health and disease, provide the practical solutions to complex human diseases that involve the interaction of those genes with the broad spectrum of "environmental factors"? Will it be "precise" enough to provide practical solutions for prevention and treatments of diseases? In this "Commentary", with the example of human carcinogenesis, it will be challenged that, without the integration of mechanistic and hypothesis-driven approaches with the "unbiased" empirical analyses of large numbers of data, the Artificial Intelligence approach with fall short.
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Affiliation(s)
- James Edward Trosko
- Department of Pediatrics/Human Development, College of Human Medicine, Michigan State University, East Lansing, MI 48824, USA
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4
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Huang T, Zhang T, Jiang X, Li A, Su Y, Bian Q, Wu H, Lin R, Li N, Cao H, Ling D, Wang J, Tabata Y, Gu Z, Gao J. Iron oxide nanoparticles augment the intercellular mitochondrial transfer-mediated therapy. SCIENCE ADVANCES 2021; 7:eabj0534. [PMID: 34586849 PMCID: PMC8480934 DOI: 10.1126/sciadv.abj0534] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 07/30/2021] [Indexed: 05/24/2023]
Abstract
The transfer of mitochondria between cells has recently been revealed as a spontaneous way to protect the injured cells. However, the utilization of this natural transfer process for disease treatment is so far limited by its unsatisfactory transfer efficiency and selectivity. Here, we demonstrate that iron oxide nanoparticles (IONPs) can augment the intercellular mitochondrial transfer from human mesenchymal stem cells (hMSCs) selectively to diseased cells, owing to the enhanced formation of connexin 43–containing gap junctional channels triggered by ionized IONPs. In a mouse model of pulmonary fibrosis, the IONP-engineered hMSCs achieve a remarkable mitigation of fibrotic progression because of the promoted intercellular mitochondrial transfer, with no serious safety issues identified. The present study reports a potential method of using IONPs to enable hMSCs for efficient and safe transfer of mitochondria to diseased cells to restore mitochondrial bioenergetics.
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Affiliation(s)
- Ting Huang
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Tianyuan Zhang
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
- Dr. Li Dak Sum and Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou 310058, China
| | - Xinchi Jiang
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
- Dr. Li Dak Sum and Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou 310058, China
| | - Ai Li
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yuanqin Su
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Qiong Bian
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Honghui Wu
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Ruyi Lin
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Ni Li
- Department of Cardiothoracic Surgery, Ningbo Medical Center, Lihuili Hospital Affiliated to Ningbo University, Ningbo, Zhejiang 315041, China
| | - Hongcui Cao
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, the First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Daishun Ling
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, National Center for Translational Medicine, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jinqiang Wang
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yasuhiko Tabata
- Department of Biomaterials, Field of Tissue Engineering, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
| | - Zhen Gu
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jianqing Gao
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
- Dr. Li Dak Sum and Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou 310058, China
- Westlake Laboratory of Life Sciences and Biomedicine, Zhejiang, China
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5
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Ray A, Mehta PP. Cysteine residues in the C-terminal tail of connexin32 regulate its trafficking. Cell Signal 2021; 85:110063. [PMID: 34146657 DOI: 10.1016/j.cellsig.2021.110063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 05/26/2021] [Accepted: 06/14/2021] [Indexed: 12/24/2022]
Abstract
Gap junctions (GJs) are formed by the assembly of constituent transmembrane proteins called connexins (Cxs). Aberrations in this assembly of Cxs are observed in several genetic diseases as well as in cancers. Hence it becomes imperative to understand the molecular mechanisms underlying such assembly defect. The polarized cells in the epithelia express Connexin32 (Cx32). The C-terminal tail (CT) of Cx32 orchestrates several aspects of GJ dynamics, function and growth. The study here was aimed at determining if post-translational modifications, specifically, palmitoylation of cysteine residues, present in the CT of Cx32, has any effect on GJ assembly. The CT of Cx32 was found to harbor three cysteine residues, which are likely to be modified by palmitoylation. The study here has revealed for the first time that Cx32 is palmitoylated at cysteine 217 (C217) in cell line derived from prostate tumors. However, it was found that mutating C217 to alanine affected neither the trafficking nor the ability of Cx32 to assemble into GJs. Intriguingly, it was discovered that mutating cysteine 280 and 283, only in combination, blocked the trafficking of Cx32 from the trans-Golgi network to the cell surface. The mutants showed reduced stability due to enhanced lysosomal degradation. Overall, the findings reveal the importance of the two C-terminal cysteine residues of Cx32 in regulating its trafficking and stability and hence its ability to assemble into GJs.
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Affiliation(s)
- Anuttoma Ray
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Parmender P Mehta
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
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6
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Gong XD, Wang Y, Hu XB, Zheng SY, Fu JL, Nie Q, Wang L, Hou M, Xiang JW, Xiao Y, Gao Q, Bai YY, Liu YZ, Li DWC. Aging-dependent loss of GAP junction proteins Cx46 and Cx50 in the fiber cells of human and mouse lenses accounts for the diminished coupling conductance. Aging (Albany NY) 2021; 13:17568-17591. [PMID: 34226295 PMCID: PMC8312418 DOI: 10.18632/aging.203247] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 06/12/2021] [Indexed: 06/13/2023]
Abstract
The homeostasis of the ocular lens is maintained by a microcirculation system propagated through gap junction channels. It is well established that the intercellular communications of the lens become deteriorative during aging. However, the molecular basis for this change in human lenses has not been well defined. Here, we present evidence to show that over 90% of Cx46 and Cx50 are lost in the fiber cells of normal human lenses aged 50 and above. From transparent to cataractous lenses, while Cx43 was upregulated, both Cx46 and Cx50 were significantly down-regulated in the lens epithelia. During aging of mouse lenses, Cx43 remained unchanged, but both Cx46 and Cx50 were significantly downregulated. Under oxidative stress treatment, mouse lenses develop in vitro cataractogenesis. Associated with this process, Cx43 was significantly upregulated, in contrast, Cx46 and Cx50 were sharply downregulated. Together, our results for the first time reveal that downregulation in Cx46 and Cx50 levels appears to be the major reason for the diminished coupling conductance, and the aging-dependent loss of Cx46 and Cx50 promotes senile cataractogenesis.
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Affiliation(s)
- Xiao-Dong Gong
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Yan Wang
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Xue-Bin Hu
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Shu-Yu Zheng
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Jia-Ling Fu
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Qian Nie
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Ling Wang
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Min Hou
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Jia-Wen Xiang
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Yuan Xiao
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Qian Gao
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Yue-Yue Bai
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Yi-Zhi Liu
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - David Wan-Cheng Li
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
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7
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Trosko JE. On the potential origin and characteristics of cancer stem cells. Carcinogenesis 2021; 42:905-912. [PMID: 34014276 DOI: 10.1093/carcin/bgab042] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 03/08/2021] [Accepted: 05/17/2021] [Indexed: 02/06/2023] Open
Abstract
The 'cancer stem cell' hypothesis has pointed to a specific target for new cancer therapies. The hypothesis is based on the observation that only the 'cancer stem cell' among the other heterogeneous cancer cells can sustain the growth of the cancer. The goal is to identify biomarkers of 'cancer stem cells' to distinguish them from the 'cancer non-stem cells' and normal adult tissue-specific stem cells. This analyst posits a hypothesis that, although all cancers originated from a single cell, there exist two types of 'cancer stem cells' either by the 'Stem Cell hypothesis' or from the 'De-differentiation hypothesis'. It is proposed that there exist two different 'cancer stem cells'. Some 'cancer stem cells' (a) lack the expression of connexins or gap junction genes and lack any form of gap junctional intercellular communication (GJIC) or (b) they have the expressed connexin-coded proteins for functional GJIC but are dysfunctional by some expressed oncogene. This is consistent with the Loewenstein hypothesis that a universal characteristic of cancer cells is they do not have growth control, nor terminally differentiate. This review speculates the normal organ-specific adult stem cell, that is 'initiated', is the origin of the 'cancer stem cells' with expressed Oct4A gene and no expressed connexin genes; whereas the other cancer stem cell has no expressed Oct4A genes but expressed connexin gene, whose coded protein is dysfunctional. Hence. both types of 'cancer stem cells' lack GJIC, for two different reasons, the selective therapies have to be different for these different cell types.
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Affiliation(s)
- James E Trosko
- Department of Pediatrics/Human Development, College of Human Medicine, Michigan State University, East Lansing, MI 48824, USA
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8
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Abstract
Membrane potential (Vmem) is a fundamental biophysical signal present in all cells. Vmem signals range in time from milliseconds to days, and they span lengths from microns to centimeters. Vmem affects many cellular processes, ranging from neurotransmitter release to cell cycle control to tissue patterning. However, existing tools are not suitable for Vmem quantification in many of these areas. In this review, we outline the diverse biology of Vmem, drafting a wish list of features for a Vmem sensing platform. We then use these guidelines to discuss electrode-based and optical platforms for interrogating Vmem. On the one hand, electrode-based strategies exhibit excellent quantification but are most effective in short-term, cellular recordings. On the other hand, optical strategies provide easier access to diverse samples but generally only detect relative changes in Vmem. By combining the respective strengths of these technologies, recent advances in optical quantification of absolute Vmem enable new inquiries into Vmem biology.
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Affiliation(s)
- Julia R Lazzari-Dean
- Department of Chemistry, University of California, Berkeley, California 94720, USA; ,
| | - Anneliese M M Gest
- Department of Chemistry, University of California, Berkeley, California 94720, USA; ,
| | - Evan W Miller
- Department of Chemistry, University of California, Berkeley, California 94720, USA; ,
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, USA
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9
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Solan JL, Lampe PD. Src Regulation of Cx43 Phosphorylation and Gap Junction Turnover. Biomolecules 2020; 10:biom10121596. [PMID: 33255329 PMCID: PMC7759836 DOI: 10.3390/biom10121596] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 11/19/2020] [Accepted: 11/22/2020] [Indexed: 12/18/2022] Open
Abstract
The gap junction protein Connexin43 (Cx43) is highly regulated by phosphorylation at over a dozen sites by probably at least as many kinases. This Cx43 “kinome” plays an important role in gap junction assembly and turnover. We sought to gain a better understanding of the interrelationship of these phosphorylation events particularly related to src activation and Cx43 turnover. Using state-of-the-art live imaging methods, specific inhibitors and many phosphorylation-status specific antibodies, we found phospho-specific domains in gap junction plaques and show evidence that multiple pathways of disassembly exist and can be regulated at the cellular and subcellular level. We found Src activation promotes formation of connexisomes (internalized gap junctions) in a process involving ERK-mediated phosphorylation of S279/282. Proteasome inhibition dramatically and rapidly restored gap junctions in the presence of Src and led to dramatic changes in the Cx43 phospho-profile including to increased Y247, Y265, S279/282, S365, and S373 phosphorylation. Lysosomal inhibition, on the other hand, nearly eliminated phosphorylation on Y247 and Y265 and reduced S368 and S373 while increasing S279/282 phosphorylation levels. We present a model of gap junction disassembly where multiple modes of disassembly are regulated by phosphorylation and can have differential effects on cellular signaling.
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Affiliation(s)
- Joell L. Solan
- Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA;
| | - Paul D. Lampe
- Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA;
- Department of Global Health, Pathobiology Program, University of Washington, Seattle, WA 98109, USA
- Correspondence:
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10
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Brink PR, Valiunas V, White TW. Lens Connexin Channels Show Differential Permeability to Signaling Molecules. Int J Mol Sci 2020; 21:ijms21186943. [PMID: 32971763 PMCID: PMC7555617 DOI: 10.3390/ijms21186943] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/18/2020] [Accepted: 09/19/2020] [Indexed: 12/12/2022] Open
Abstract
Gap junction channels mediate the direct intercellular passage of small ions as well as larger solutes such as second messengers. A family of proteins called connexins make up the subunits of gap junction channels in chordate animals. Each individual connexin forms channels that exhibit distinct permeability to molecules that influence cellular signaling, such as calcium ions, cyclic nucleotides, or inositol phosphates. In this review, we examine the permeability of connexin channels containing Cx43, Cx46, and Cx50 to signaling molecules and attempt to relate the observed differences in permeability to possible in vivo consequences that were revealed by studies of transgenic animals where these connexin genes have been manipulated. Taken together, these data suggest that differences in the permeability of individual connexin channels to larger solutes like 3',5'-cyclic adenosine monophosphate (cAMP) and inositol 1,4,5-trisphosphate (IP3) could play a role in regulating epithelial cell division, differentiation, and homeostasis in organs like the ocular lens.
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11
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Silva HVR, da Silva AM, Lee PC, Brito BF, Silva AR, da Silva LDM, Comizzoli P. Influence of Microwave-Assisted Drying on Structural Integrity and Viability of Testicular Tissues from Adult and Prepubertal Domestic Cats. Biopreserv Biobank 2020; 18:415-424. [PMID: 32780644 DOI: 10.1089/bio.2020.0048] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Anhydrous preservation is a promising approach for storage of living biomaterials at nonfreezing temperatures. Using the domestic cat model, the objectives of this study were to characterize changes in histology, DNA integrity, and viability of testicular tissues from adult versus prepubertal individuals during microwave-assisted drying. Testes from each age group were cut into small pieces before reversible membrane permeabilization, exposure to trehalose, and microwave-assisted drying during different time periods. In Experiment 1, water content was monitored for up to 40 minutes of drying. Tissues from adult or prepubertal cats experienced similar decreases of water content during the first 10 minutes. Desiccation progressed slowly between 10 and 20 minutes and then remained stable. In Experiment 2, structural properties were explored at 5, 10, and 20 minutes of desiccation. Percentages of normal seminiferous tubules were lower after 20 minutes drying in adult (43%) than in prepubertal tissues (61%). At the same time point, the proportion of cell degeneration was higher in adult (53%) than prepubertal tissues (28%). Percentages of intact DNA in tissues remained above 85% regardless of the microwave time in both age groups. Lastly, adult and prepubertal tissues only lost 33% of viability in both age groups. Collective results demonstrated for the first time that normal morphology, incidence of degeneration, DNA integrity, and viability of testicular tissues remained at acceptable levels during microwave-assisted drying for 20 minutes. Overall, prepubertal testicular tissues appeared to be more resilient to microwave-assisted desiccations than adult tissues. Importantly, water loss in the presence of trehalose after 20 minutes of desiccation already is compatible with long-term storage of testicular tissues at temperatures above -20°C, which is one step closer to future storage at supra-zero temperatures.
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Affiliation(s)
| | - Andréia Maria da Silva
- Laboratory of Animal Germplasm Conservation, Federal Rural University of Semi-Arid, Mossoró, Brazil
| | - Pei-Chih Lee
- Smithsonian Conservation Biology Institute, National Zoological Park, Washington, District of Columbia, USA
| | - Bruna Farias Brito
- Laboratory of Carnivores Reproduction, State University of Ceará, Fortaleza, Brazil
| | | | | | - Pierre Comizzoli
- Smithsonian Conservation Biology Institute, National Zoological Park, Washington, District of Columbia, USA
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12
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Schmitt LI, Leo M, Kutritz A, Kleinschnitz C, Hagenacker T. Activation and functional modulation of satellite glial cells by oxaliplatin lead to hyperexcitability of sensory neurons in vitro. Mol Cell Neurosci 2020; 105:103499. [PMID: 32389805 DOI: 10.1016/j.mcn.2020.103499] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/28/2020] [Accepted: 05/03/2020] [Indexed: 01/24/2023] Open
Abstract
Platinum-based chemotherapeutics still play an important role in cancer therapy, however, severe side effects, such as painful neuropathy, occur frequently. The pathophysiologic mechanisms depend on the applied chemotherapeutic agent and are still controversial. In addition to neuronal damage, disturbance of glial cell activity may contribute to neurotoxicity. Here, we focused on the effect of oxaliplatin on satellite glial cell (SGC) function and on the activity of the dorsal root ganglion (DRG) neurons. SGCs were isolated as high-purity cultures and treated with 1 and 10 μM oxaliplatin for 2, 4 and 24 h. Subsequently, glial fibrillary acid protein (GFAP), reactive oxygen species (ROS), Connexin-43 (Cx-43), and inward rectifier potassium channel 4.1 (Kir4.1) expression was determined by immunocytochemical staining (ICC) and Western blot analyses. Immunochemical staining and Western blot analysis showed an increase in the immune reactivity (IR) and protein levels of ROS, GFAP, and Cx-43. Furthermore, reduction of the IR and protein levels and current density were demonstrated using patch-clamp measurements, of Kir4.1 channels after oxaliplatin exposure. Cytokine release in SGCs was measured using enzyme-linked immunosorbent assays (ELISA) after oxaliplatin exposure and indicated an increased release of IL-6 and TNFα, while IL-1β was decreased. The direct influence of SGC-secreted factors in the supernatant after oxaliplatin treatment led to the hyperexcitability of cultured DRG neurons. In summary, oxaliplatin has a direct impact on the modulation and function of different SGC proteins. Furthermore, SGC-released factors influence the excitability of sensory neurons, qualifying SGCs as potential targets for the prevention and treatment of oxaliplatin-induced polyneuropathy.
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Affiliation(s)
| | - Markus Leo
- Department of Neurology, Neuroscience Lab, University Hospital Essen, Germany
| | - Andrea Kutritz
- Department of Neurology, Neuroscience Lab, University Hospital Essen, Germany
| | | | - Tim Hagenacker
- Department of Neurology, Neuroscience Lab, University Hospital Essen, Germany.
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Wu HC, Chang HM, Yi Y, Sun ZG, Lin YM, Lian F, Leung PCK. Bone morphogenetic protein 6 affects cell-cell communication by altering the expression of Connexin43 in human granulosa-lutein cells. Mol Cell Endocrinol 2019; 498:110548. [PMID: 31434001 DOI: 10.1016/j.mce.2019.110548] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 08/06/2019] [Accepted: 08/17/2019] [Indexed: 11/25/2022]
Abstract
Connexin 43 (Cx43)-coupled gap junctions in granulosa cells play an important role in follicular development, oocyte maturation, and corpus luteum maintenance. Bone morphogenetic protein 6 (BMP6) is highly expressed in human oocytes and granulosa cells and is involved in the regulation of female reproduction. Currently, whether oocyte- and granulosa cell-derived BMP6 affects the expression of Cx43 and its related gap junction intercellular communication (GJIC) activity in human granulosa cells remains unknown. In this study, we demonstrate that BMP6 treatment significantly suppressed the expression of Cx43 in both primary and immortalized (SVOG) human granulosa-lutein cells. Using both pharmacological inhibitors and small interfering RNA-mediated knockdown approaches, we demonstrate that ALK2 and ALK3 BMP type I receptors are involved in BMP6-induced suppressive effects on Cx43 expression and GJIC activity in SVOG cells. Furthermore, these cellular activities are most likely mediated by the SMAD1/SMAD5-SMAD4-dependent signaling pathway. Notably, the ChIP analyses demonstrated that phosphorylated SMADs could bind to human Cx43 promoter. Our findings provide new insight into the molecular mechanisms by which an intrafollicular growth factor regulates cell-cell communication in human granulosa cells.
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Affiliation(s)
- Hai-Cui Wu
- Integrative Medicine Research Centre of Reproduction and Heredity, The Affiliated Hospital of Shandong University of Traditional Chinese Medicine, China; Department of Obstetrics and Gynaecology, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, British Columbia, V6H 3V5, Canada
| | - Hsun-Ming Chang
- Integrative Medicine Research Centre of Reproduction and Heredity, The Affiliated Hospital of Shandong University of Traditional Chinese Medicine, China; Department of Obstetrics and Gynaecology, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, British Columbia, V6H 3V5, Canada
| | - Yuyin Yi
- Department of Obstetrics and Gynaecology, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, British Columbia, V6H 3V5, Canada
| | - Zhen-Gao Sun
- Integrative Medicine Research Centre of Reproduction and Heredity, The Affiliated Hospital of Shandong University of Traditional Chinese Medicine, China; Department of Obstetrics and Gynaecology, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, British Columbia, V6H 3V5, Canada
| | - Yung-Ming Lin
- Integrative Medicine Research Centre of Reproduction and Heredity, The Affiliated Hospital of Shandong University of Traditional Chinese Medicine, China; Department of Obstetrics and Gynaecology, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, British Columbia, V6H 3V5, Canada
| | - Fang Lian
- Integrative Medicine Research Centre of Reproduction and Heredity, The Affiliated Hospital of Shandong University of Traditional Chinese Medicine, China.
| | - Peter C K Leung
- Integrative Medicine Research Centre of Reproduction and Heredity, The Affiliated Hospital of Shandong University of Traditional Chinese Medicine, China; Department of Obstetrics and Gynaecology, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, British Columbia, V6H 3V5, Canada.
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14
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Abstract
BACKGROUND Gap junctions (GJ) are one of the most common forms of intercellular communication. GJs are assembled from proteins that form channels connecting the cytoplasm of adjacent cells. They are considered to be the main or the only type of intercellular channels and the universal feature of all multicellular animals. Two unrelated protein families are currently considered to be involved in this function, namely, connexins and pannexins (pannexins/innexins). Pannexins were hypothesized to be the universal GJ proteins of multicellular animals, distinct from connexins that are characteristic of chordates only. Here we have revised this supposition by applying growing high throughput sequencing data from diverse metazoan species. RESULTS Pannexins were found in Chordates, Ctenophores, Cnidarians, and in the most major groups of bilateral protostomes. Yet some metazoans appear to have neither connexins nor pannexins in their genomes. We detected no connexins or pannexins/innexins homologues in representatives of all five classes of echinoderms and their closest relatives hemichordates with available genomic sequences. Despite this, our intracellular recordings demonstrate direct electrical coupling between blastomeres at the 2-cell embryo of the echinoderm (starfish Asterias rubens). In these experiments, carboxyfluorescein fluorescent dye did not diffuse between electrically coupled cells. This excludes the possibility that the observed electrical coupling is mediated by incomplete cytoplasm separation during cleavage. CONCLUSION Functional GJs are present in representatives of the clade that lack currently recognized GJ protein families. New undiscovered protein families utilized for intercellular channels are predicted. It is possible that the new type(s) of intercellular channels are present in parallel to pannexin and connexin gap junctions in animal groups, other than Echinodermata.
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Affiliation(s)
- Georgy A Slivko-Koltchik
- Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russian Federation, 127994
| | - Victor P Kuznetsov
- Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russian Federation, 127994
| | - Yuri V Panchin
- Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russian Federation, 127994.
- A.N. Belozersky Institute of Physico-Chemical Biology Moscow State University, Moscow, Russian Federation, 119991.
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15
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Mugisho OO, Green CR, Zhang J, Acosta ML, Rupenthal ID. Connexin43 hemichannels: A potential drug target for the treatment of diabetic retinopathy. Drug Discov Today 2019; 24:1627-1636. [PMID: 30690195 DOI: 10.1016/j.drudis.2019.01.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 01/17/2019] [Accepted: 01/17/2019] [Indexed: 02/07/2023]
Abstract
Diabetic retinopathy (DR) is a chronic vascular disease of the retina that causes vision loss in patients with type 1 and type 2 diabetes, and is associated with vascular dysfunction and occlusion, retinal oedema, haemorrhage and inadequate growth of new blood vessels. Current DR therapies primarily target downstream, later-stage vascular defects with a significant proportion of diabetic macular oedema patients being non-responders. Moreover, other evidence suggests that prolonged use of therapies targeting vascular endothelial growth factor (VEGF) might be associated with increased onset of geographic atrophy and retinal ganglion cell death. It is therefore highly desirable to prevent the onset of DR or arrest its progression at a stage preceding the appearance of more-advanced pathology by targeting upstream disease mechanisms. Connexin43 hemichannels play a part in the pathogenesis of chronic inflammatory diseases, including inflammasome pathway activation; and hemichannel block has been shown to alleviate vascular leak and inflammation. This review discusses the inflammatory changes occurring in DR as well as current therapies and their limitations. It then focuses on the role of connexin43 in DR, providing evidence for the utility of connexin43 hemichannel blockers as novel therapeutics for DR treatment.
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Affiliation(s)
- Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology and the New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology and the New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Jie Zhang
- Department of Ophthalmology and the New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Monica L Acosta
- School of Optometry and Vision Science and the New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology and the New Zealand National Eye Centre, University of Auckland, New Zealand.
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16
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Plasticity of the Electrical Connectome of C. elegans. Cell 2019; 176:1174-1189.e16. [PMID: 30686580 PMCID: PMC10064801 DOI: 10.1016/j.cell.2018.12.024] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/12/2018] [Accepted: 12/14/2018] [Indexed: 11/23/2022]
Abstract
The specific patterns and functional properties of electrical synapses of a nervous system are defined by the neuron-specific complement of electrical synapse constituents. We systematically examined the molecular composition of the electrical connectome of the nematode C. elegans through a genome- and nervous-system-wide analysis of the expression patterns of the invertebrate electrical synapse constituents, the innexins. We observe highly complex combinatorial expression patterns throughout the nervous system and found that these patterns change in a strikingly neuron-type-specific manner throughout the nervous system when animals enter an insulin-controlled diapause arrest stage under harsh environmental conditions, the dauer stage. By analyzing several individual synapses, we demonstrate that dauer-specific electrical synapse remodeling is responsible for specific aspects of the altered locomotory and chemosensory behavior of dauers. We describe an intersectional gene regulatory mechanism involving terminal selector and FoxO transcription factors mediating dynamic innexin expression plasticity in a neuron-type- and environment-specific manner.
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17
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Trosko JE. Cancer Prevention and Therapy of Two Types of Gap Junctional Intercellular Communication⁻Deficient "Cancer Stem Cell". Cancers (Basel) 2019; 11:cancers11010087. [PMID: 30646567 PMCID: PMC6356618 DOI: 10.3390/cancers11010087] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 12/23/2018] [Accepted: 01/08/2019] [Indexed: 12/21/2022] Open
Abstract
Early observations showed a lack of growth control and terminal differentiation with a lack of gap junctional intercellular communication (GJIC). Subsequent observations showed that epigenetic tumor promoters and activated oncogenes, which block gap junction function, provide insights into the multi-stage, multi-mechanism carcinogenic process. With the isolation of embryonic induced pluri-potent stem cells and organ-specific adult stem cells, gap junctions were linked to early development. While tumors and tumor cell lines are a heterogeneous mixture of "cancer stem cells" and "cancer non-stem cells", the cancer stem cells seem to be of two types, namely, they express (a) no connexin genes or (b) connexin genes, but do not have functional GJIC. These observations suggest that these "cancer stem cells" originate from normal adult stem cells or from the de-differentiation or re-programming of somatic differentiated cells. This "Concept Paper" provides a hypothesis that "cancer stem cells" either originate from (a) organ-specific adult stem cells before the expression of the connexin genes or (b) organ-specific adult stem cells that just express gap junction genes but that the connexin proteins are rendered dysfunctional by activated oncogenes. Therefore, cancer prevention and therapeutic strategies must account for these two different types of "cancer stem cell".
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Affiliation(s)
- James E Trosko
- Department Pediatrics & Human Development, College of Human Medicine, Michigan State University, East Lansing, MI 48824, USA.
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18
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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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19
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Gago-Fuentes R, Bechberger JF, Varela-Eirin M, Varela-Vazquez A, Acea B, Fonseca E, Naus CC, Mayan MD. The C-terminal domain of connexin43 modulates cartilage structure via chondrocyte phenotypic changes. Oncotarget 2018; 7:73055-73067. [PMID: 27682878 PMCID: PMC5341963 DOI: 10.18632/oncotarget.12197] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 09/16/2016] [Indexed: 12/13/2022] Open
Abstract
Chondrocytes in cartilage and bone cells population express connexin43 (Cx43) and gap junction intercellular communication (GJIC) is essential to synchronize cells for coordinated electrical, mechanical, metabolic and chemical communication in both tissues. Reduced Cx43 connectivity decreases chondrocyte differentiation and defective Cx43 causes skeletal defects. The carboxy terminal domain (CTD) of Cx43 is located in the cytoplasmic side and is key for protein functions. Here we demonstrated that chondrocytes from the CTD-deficient mice, K258stop/Cx43KO and K258stop/K258stop, have reduced GJIC, increased rates of proliferation and reduced expression of collagen type II and proteoglycans. We observed that CTD-truncated mice were significantly smaller in size. Together these results demonstrated that the deletion of the CTD negatively impacts cartilage structure and normal chondrocyte phenotype. These findings suggest that the proteolytic cleavage of the CTD under pathological conditions, such as under the activation of metalloproteinases during tissue injury or inflammation, may account for the deleterious effects of Cx43 in cartilage and bone disorders such as osteoarthritis.
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Affiliation(s)
- Raquel Gago-Fuentes
- CellCOM-SB Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), CH-Universitario A Coruña (XXIAC), University of A Coruña, Servizo Galego de Saúde (SERGAS), Xubias de Arriba, 84 15006 A Coruña, Spain
| | - John F Bechberger
- Department of Cellular and Physiological Sciences, The Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z3
| | - Marta Varela-Eirin
- CellCOM-SB Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), CH-Universitario A Coruña (XXIAC), University of A Coruña, Servizo Galego de Saúde (SERGAS), Xubias de Arriba, 84 15006 A Coruña, Spain
| | - Adrian Varela-Vazquez
- CellCOM-SB Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), CH-Universitario A Coruña (XXIAC), University of A Coruña, Servizo Galego de Saúde (SERGAS), Xubias de Arriba, 84 15006 A Coruña, Spain
| | - Benigno Acea
- CellCOM-SB Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), CH-Universitario A Coruña (XXIAC), University of A Coruña, Servizo Galego de Saúde (SERGAS), Xubias de Arriba, 84 15006 A Coruña, Spain
| | - Eduardo Fonseca
- CellCOM-SB Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), CH-Universitario A Coruña (XXIAC), University of A Coruña, Servizo Galego de Saúde (SERGAS), Xubias de Arriba, 84 15006 A Coruña, Spain
| | - Christian C Naus
- Department of Cellular and Physiological Sciences, The Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z3
| | - Maria D Mayan
- CellCOM-SB Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), CH-Universitario A Coruña (XXIAC), University of A Coruña, Servizo Galego de Saúde (SERGAS), Xubias de Arriba, 84 15006 A Coruña, Spain
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20
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21
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Liu L, Li XB, Hu ZHM, Zi XH, Zhao X, Xie YZ, Huang SHX, Xia K, Tang BS, Zhang RX. Phenotypes and cellular effects of GJB1 mutations causing CMT1X in a cohort of 226 Chinese CMT families. Clin Genet 2017; 91:881-891. [PMID: 27804109 DOI: 10.1111/cge.12913] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/26/2016] [Accepted: 10/28/2016] [Indexed: 12/23/2022]
Abstract
The aim of this study is to explore the phenotypic and genotypic features of X-linked Charcot-Marie-Tooth (CMT) disease in the mainland of China and to study the cellular effects of six novel Gap junction protein beta-1 variants. We identified 25 missense and 1 non-sense mutations of GJB1 in 31 unrelated families out of 226 CMT families. The frequency of GJB1 mutations was 13.7% of the total and 65% of intermediate CMT. Six novel GJB1 variants (c.5A>G, c.8G>A, c.242T>C, c.269T>C, c.317T>C and c.434T>G) were detected in six unrelated intermediate CMT families. Fluorescence revealed that HeLa cells transfected with EGFP-GJB1-V74M, EGFP-GJB1-L81P or EGFP-GJB1-L90P had diffuse endoplasmic reticulum staining, HeLa cells transfected with EGFP-GJB1-L106P had diffuse intracellular staining, and HeLa cells transfected with EGFP-GJB1-N2S had cytoplasmic and nuclear staining. The distribution of Cx32 in HeLa cells transfected with EGFP-GJB1-F145C was similar to that of those transfected with wild-type (WT). These six variants resulted in a higher percentage of apoptosis than did WT as detected by flow cytometry and Hoechst staining. In conclusion, mutation screening should be first performed in intermediate CMT patients, especially those with additional features. The novel GJB1 variants c.5A>G, c.8G>A, c.242T>C and c.269T>C are considered pathogenic, and c.317T>C and c.434T>G are classified as probably pathogenic.
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Affiliation(s)
- L Liu
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - X B Li
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Z H M Hu
- National Key Lab of Medical Genetics, Central South University, Changsha, China
| | - X H Zi
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - X Zhao
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Y Z Xie
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - S H X Huang
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - K Xia
- National Key Lab of Medical Genetics, Central South University, Changsha, China
| | - B S Tang
- National Key Lab of Medical Genetics, Central South University, Changsha, China
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - R X Zhang
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
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22
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Srinivas M, Verselis VK, White TW. Human diseases associated with connexin mutations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:192-201. [PMID: 28457858 DOI: 10.1016/j.bbamem.2017.04.024] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 04/20/2017] [Accepted: 04/25/2017] [Indexed: 01/11/2023]
Abstract
Gap junctions and hemichannels comprised of connexins impact many cellular processes. Significant advances in our understanding of the functional role of these channels have been made by the identification of a host of genetic diseases caused by connexin mutations. Prominent features of connexin disorders are the inability of other connexins expressed in the same cell type to compensate for the mutated one, and the ability of connexin mutants to dominantly influence the activity of other wild-type connexins. Functional studies have begun to identify some of the underlying mechanisms whereby connexin channel mutation contributes to the disease state. Detailed mechanistic understanding of these functional differences will help to facilitate new pathophysiology driven therapies for the diverse array of connexin genetic disorders. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Miduturu Srinivas
- Department of Biological and Vision Sciences, SUNY College of Optometry, New York, NY 10036, USA
| | - Vytas K Verselis
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Thomas W White
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794, USA.
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23
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Norris RP, Baena V, Terasaki M. Localization of phosphorylated connexin 43 by serial section immunogold electron microscopy. J Cell Sci 2017; 130:1333-1340. [DOI: 10.1242/jcs.198408] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 02/09/2017] [Indexed: 02/05/2023] Open
Abstract
Gap junction turnover occurs by the internalization of both plasma membranes of a gap junction plaque to form a double membrane-enclosed vesicle, or connexosome. Phosphorylation has a key role in regulation, but further progress requires clearly distinguishing gap junctions and connexosomes and precisely localizing proteins to them. We examined by electron microscopy serial sections of mouse preovulatory ovarian follicles collected with an automated tape collecting ultramicrotome (ATUM). We found connexosomes may form from adjacent cell bodies, from thin cell processes, or from the same cell. By immunolabeling serial sections, we found S368 of connexin 43 is phosphorylated on gap junctions and connexosomes, whereas S262 is phosphorylated only on some connexosomes. These data suggest that S262 phosphorylation contributes to connexosome formation or processing, and provide more precise evidence that phosphorylation has a key role in gap junction internalization. Serial section electron microscopy of immunogold-labeled tissues offers a new way for investigating the three-dimensional organization of cells in their native environment.
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Affiliation(s)
- Rachael P. Norris
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Valentina Baena
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
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24
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Hidaka S. Conflicting effects by antibodies against connexin36 during the action of intracellular Cyclic-AMP onto electrical synapses of retinal ganglion cells. J Integr Neurosci 2016; 15:571-591. [PMID: 28052704 DOI: 10.1142/s021963521650031x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
Alpha-type retinal ganglion cells (alpha cells) of the same class in mammalian retina are connected by gap junctions. Electrical synapses between alpha cells were examined using combined techniques of dual patch-clamp recordings, intracellular labeling and electron microscopy in the albino rat retina. In simultaneous dual whole-cell recordings from pairs of neighboring alpha cells, bidirectional electrical synapses with symmetrical junction conductance were observed in pairs with cells of the same morphological type. Regulatory domains of gap junction protein subunit connexins in electrical synapses between alpha cells by extracellular and intracellular ligands investigated by dual whole-patch clamp recordings. I examined how passage currents through electrical synapses between alpha cells are modulated by specific antibodies against connexin36 proteins, and extracellular or intracellular application of ligands. Control conditions led us to observe large passage currents between connected cells and adequate transjunctional conductance (Gj) (1.35[Formula: see text][Formula: see text][Formula: see text]0.51[Formula: see text]nS). Experimental results show that high level of intracellular cyclic AMP within examined cells suppress electrical synapses between the neighboring cells. Gj between examined cells reduced to 0.15[Formula: see text][Formula: see text][Formula: see text]0.04[Formula: see text]nS. Under application of dopamine (1.25[Formula: see text][Formula: see text][Formula: see text]0.06[Formula: see text]nS) or intracellular cyclic GMP (0.98[Formula: see text][Formula: see text][Formula: see text]0.23[Formula: see text]nS), however, Gj also remains as in the control level. Intracellular application of an antibody against the cytoplasmic loop of connexin36 reduced Gj (0.98[Formula: see text][Formula: see text][Formula: see text]0.23[Formula: see text]nS). Cocktail of the antibody against cytoplasmic connexin36 and intracellular cyclic AMP leaves Gj as in the level by single involvement of the cytoplasmic antibody. The elimination of Gj by the cytoplasmic antibody was in a dose-dependent manner. These results suggest that binding domains against cyclic AMP may be present in the cytoplasmic sites of connexin proteins to regulate channel opening of gap junctions between mammalian retinal alpha ganglion cells.
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Affiliation(s)
- Soh Hidaka
- 1 Department of Physiology, Fujita Health University School of Medicine, Toyoake Aichi 470-1192, Japan
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25
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Nighot P, Ma T. Role of autophagy in the regulation of epithelial cell junctions. Tissue Barriers 2016; 4:e1171284. [PMID: 27583189 DOI: 10.1080/21688370.2016.1171284] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 03/21/2016] [Accepted: 03/22/2016] [Indexed: 01/07/2023] Open
Abstract
Autophagy is a cell survival mechanism by which bulk cytoplasmic material, including soluble macromolecules and organelles, is targeted for lysosomal degradation. The role of autophagy in diverse cellular processes such as metabolic stress, neurodegeneration, cancer, aging, immunity, and inflammatory diseases is being increasingly recognized. Epithelial cell junctions play an integral role in the cell homeostasis via physical binding, regulating paracellular pathways, integrating extracellular cues into intracellular signaling, and cell-cell communication. Recent data indicates that cell junction composition is very dynamic. The junctional protein complexes are actively regulated in response to various intra- and extra-cellular clues by intracellular trafficking and degradation pathways. This review discusses the recent and emerging information on how autophagy regulates various epithelial cell junctions. The knowledge of autophagy regulation of epithelial junctions will provide further rationale for targeting autophagy in a wide variety of human disease conditions.
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Affiliation(s)
- Prashant Nighot
- Department of Internal Medicine, University of New Mexico School of Medicine , Albuquerque, NM, USA
| | - Thomas Ma
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA; Veterans Affairs Medical Center, Albuquerque, NM, USA
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26
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Lavrov I, Fox L, Shen J, Han Y, Cheng J. Gap Junctions Contribute to the Regulation of Walking-Like Activity in the Adult Mudpuppy (Necturus Maculatus). PLoS One 2016; 11:e0152650. [PMID: 27023006 PMCID: PMC4811563 DOI: 10.1371/journal.pone.0152650] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 03/17/2016] [Indexed: 12/03/2022] Open
Abstract
Although gap junctions are widely expressed in the developing central nervous system, the role of electrical coupling of neurons and glial cells via gap junctions in the spinal cord in adults is largely unknown. We investigated whether gap junctions are expressed in the mature spinal cord of the mudpuppy and tested the effects of applying gap junction blocker on the walking-like activity induced by NMDA or glutamate in an in vitro mudpuppy preparation. We found that glial and neural cells in the mudpuppy spinal cord expressed different types of connexins that include connexin 32 (Cx32), connexin 36 (Cx36), connexin 37 (Cx37), and connexin 43 (Cx43). Application of a battery of gap junction blockers from three different structural classes (carbenexolone, flufenamic acid, and long chain alcohols) substantially and consistently altered the locomotor-like activity in a dose-dependent manner. In contrast, these blockers did not significantly change the amplitude of the dorsal root reflex, indicating that gap junction blockers did not inhibit neuronal excitability nonselectively in the spinal cord. Taken together, these results suggest that gap junctions play a significant modulatory role in the spinal neural networks responsible for the generation of walking-like activity in the adult mudpuppy.
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Affiliation(s)
- Igor Lavrov
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia
| | - Lyle Fox
- Departments of Pain Management and Neurosciences, Anesthesiology Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Jun Shen
- Departments of Pain Management and Neurosciences, Anesthesiology Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Yingchun Han
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Jianguo Cheng
- Departments of Pain Management and Neurosciences, Anesthesiology Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- * E-mail:
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Kumar P, Kumar D, Jha SK, Jha NK, Ambasta RK. Ion Channels in Neurological Disorders. ION CHANNELS AS THERAPEUTIC TARGETS, PART A 2016; 103:97-136. [DOI: 10.1016/bs.apcsb.2015.10.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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SAITO M, IMAI K, KOYAMA M. A Tetracysteine-tag and HeLa Cell System for the Dynamic Analysis of the Localization and Gating Properties of a Specific Connexin Isoform. ELECTROCHEMISTRY 2016. [DOI: 10.5796/electrochemistry.84.299] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Mikako SAITO
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology
| | - Keiichi IMAI
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology
| | - Masato KOYAMA
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology
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Kinase programs spatiotemporally regulate gap junction assembly and disassembly: Effects on wound repair. Semin Cell Dev Biol 2015; 50:40-8. [PMID: 26706150 DOI: 10.1016/j.semcdb.2015.12.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 12/08/2015] [Indexed: 01/05/2023]
Abstract
Gap junctions are highly ordered plasma membrane domains that are constantly assembled, remodeled and turned over due to the short half-life of connexins, the integral membrane proteins that form gap junctions. Connexin 43 (Cx43), by far the most widely expressed connexin, is phosphorylated at multiple serine residues in the cytoplasmic, C-terminal region allowing for exquisite cellular control over gap junctional communication. This is evident during epidermal wounding where spatiotemporal changes in connexin expression occur as cells are instructed whether to die, proliferate or migrate to promote repair. Early gap junctional communication is required for initiation of keratinocyte migration, but accelerated Cx43 turnover is also critical for proper wound healing at later stages. These events are controlled via a "kinase program" where sequential phosphorylation of Cx43 leads to reductions in Cx43's half-life and significant depletion of gap junctions from the plasma membrane within several hours. The complex regulation of gap junction assembly and turnover affords several steps where intervention might speed wound healing.
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Tang C, Chen X, Chi J, Yang D, Liu S, Liu M, Pan Q, Fan J, Wang D, Zhang Z. Pathogenic Cx31 is un/misfolded to cause skin abnormality via a Fos/JunB-mediated mechanism. Hum Mol Genet 2015; 24:6054-65. [DOI: 10.1093/hmg/ddv317] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Accepted: 07/31/2015] [Indexed: 01/29/2023] Open
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Abstract
Cell-to-cell communications via the tunneling nanotubes or gap junction channels are vital for the development and maintenance of multicellular organisms. Instead of these intrinsic communication pathways, how to design artificial communication channels between cells remains a challenging but interesting problem. Here, we perform dissipative particle dynamics (DPD) simulations to analyze the interaction between rotational nanotubes (RNTs) and vesicles so as to provide a novel design mechanism for cell-to-cell communication. Simulation results have demonstrated that the RNTs are capable of generating local disturbance and promote vesicle translocation toward the RNTs. Through ligand pattern designing on the RNTs, we can find a suitable nanotube candidate with a specific ligand coating pattern for forming the RNT-vesicle network. The results also show that a RNT can act as a bridged channel between vesicles, which facilitates substance transfer. Our findings provide useful guidelines for the molecular design of patterned RNTs for creating a synthetic channel between cells.
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Affiliation(s)
- Liuyang Zhang
- College of Engineering and NanoSEC, University of Georgia, Athens, Georgia 30602, United States
| | - Xianqiao Wang
- College of Engineering and NanoSEC, University of Georgia, Athens, Georgia 30602, United States
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Hitomi M, Deleyrolle LP, Mulkearns-Hubert EE, Jarrar A, Li M, Sinyuk M, Otvos B, Brunet S, Flavahan WA, Hubert CG, Goan W, Hale JS, Alvarado AG, Zhang A, Rohaus M, Oli M, Vedam-Mai V, Fortin JM, Futch HS, Griffith B, Wu Q, Xia CH, Gong X, Ahluwalia MS, Rich JN, Reynolds BA, Lathia JD. Differential connexin function enhances self-renewal in glioblastoma. Cell Rep 2015; 11:1031-42. [PMID: 25959821 PMCID: PMC4502443 DOI: 10.1016/j.celrep.2015.04.021] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 03/10/2015] [Accepted: 04/07/2015] [Indexed: 12/17/2022] Open
Abstract
The coordination of complex tumor processes requires cells to rapidly modify their phenotype and is achieved by direct cell-cell communication through gap junction channels composed of connexins. Previous reports have suggested that gap junctions are tumor suppressive based on connexin 43 (Cx43), but this does not take into account differences in connexin-mediated ion selectivity and intercellular communication rate that drive gap junction diversity. We find that glioblastoma cancer stem cells (CSCs) possess functional gap junctions that can be targeted using clinically relevant compounds to reduce self-renewal and tumor growth. Our analysis reveals that CSCs express Cx46, while Cx43 is predominantly expressed in non-CSCs. During differentiation, Cx46 is reduced, while Cx43 is increased, and targeting Cx46 compromises CSC maintenance. The difference between Cx46 and Cx43 is reflected in elevated cell-cell communication and reduced resting membrane potential in CSCs. Our data demonstrate a pro-tumorigenic role for gap junctions that is dependent on connexin expression.
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Affiliation(s)
- Masahiro Hitomi
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA; Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA
| | - Loic P Deleyrolle
- Department of Neurosurgery, University of Florida, Gainesville, FL 32610-0261, USA
| | - Erin E Mulkearns-Hubert
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - Awad Jarrar
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - Meizhang Li
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - Maksim Sinyuk
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - Balint Otvos
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - Sylvain Brunet
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - William A Flavahan
- Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - Christopher G Hubert
- Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - Winston Goan
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - James S Hale
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - Alvaro G Alvarado
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA; Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA
| | - Ao Zhang
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - Mark Rohaus
- Department of Neurosurgery, University of Florida, Gainesville, FL 32610-0261, USA
| | - Muna Oli
- Department of Neurosurgery, University of Florida, Gainesville, FL 32610-0261, USA
| | - Vinata Vedam-Mai
- Department of Neurosurgery, University of Florida, Gainesville, FL 32610-0261, USA
| | - Jeff M Fortin
- Department of Neurosurgery, University of Florida, Gainesville, FL 32610-0261, USA
| | - Hunter S Futch
- Department of Neurosurgery, University of Florida, Gainesville, FL 32610-0261, USA
| | - Benjamin Griffith
- Department of Neurosurgery, University of Florida, Gainesville, FL 32610-0261, USA
| | - Qiulian Wu
- Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA
| | - Chun-Hong Xia
- Berkeley Stem Cell Center, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Xiaohua Gong
- Berkeley Stem Cell Center, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Manmeet S Ahluwalia
- Rose Ella Burkhardt Brain Tumor and Neuro Oncology Center, Cleveland Clinic, Cleveland, OH 44195, USA; Case Comprehensive Cancer Center, Cleveland, OH 44106, USA
| | - Jeremy N Rich
- Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA; Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA; Rose Ella Burkhardt Brain Tumor and Neuro Oncology Center, Cleveland Clinic, Cleveland, OH 44195, USA; Case Comprehensive Cancer Center, Cleveland, OH 44106, USA
| | - Brent A Reynolds
- Department of Neurosurgery, University of Florida, Gainesville, FL 32610-0261, USA.
| | - Justin D Lathia
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44915, USA; Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA; Rose Ella Burkhardt Brain Tumor and Neuro Oncology Center, Cleveland Clinic, Cleveland, OH 44195, USA; Case Comprehensive Cancer Center, Cleveland, OH 44106, USA.
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Hall MA, Verma SS, Wallace J, Lucas A, Berg RL, Connolly J, Crawford DC, Crosslin DR, de Andrade M, Doheny KF, Haines JL, Harley JB, Jarvik GP, Kitchner T, Kuivaniemi H, Larson EB, Carrell DS, Tromp G, Vrabec TR, Pendergrass SA, McCarty CA, Ritchie MD. Biology-Driven Gene-Gene Interaction Analysis of Age-Related Cataract in the eMERGE Network. Genet Epidemiol 2015; 39:376-84. [PMID: 25982363 PMCID: PMC4550090 DOI: 10.1002/gepi.21902] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 02/27/2015] [Accepted: 03/13/2015] [Indexed: 01/19/2023]
Abstract
Bioinformatics approaches to examine gene-gene models provide a means to discover interactions between multiple genes that underlie complex disease. Extensive computational demands and adjusting for multiple testing make uncovering genetic interactions a challenge. Here, we address these issues using our knowledge-driven filtering method, Biofilter, to identify putative single nucleotide polymorphism (SNP) interaction models for cataract susceptibility, thereby reducing the number of models for analysis. Models were evaluated in 3,377 European Americans (1,185 controls, 2,192 cases) from the Marshfield Clinic, a study site of the Electronic Medical Records and Genomics (eMERGE) Network, using logistic regression. All statistically significant models from the Marshfield Clinic were then evaluated in an independent dataset of 4,311 individuals (742 controls, 3,569 cases), using independent samples from additional study sites in the eMERGE Network: Mayo Clinic, Group Health/University of Washington, Vanderbilt University Medical Center, and Geisinger Health System. Eighty-three SNP-SNP models replicated in the independent dataset at likelihood ratio test P < 0.05. Among the most significant replicating models was rs12597188 (intron of CDH1)-rs11564445 (intron of CTNNB1). These genes are known to be involved in processes that include: cell-to-cell adhesion signaling, cell-cell junction organization, and cell-cell communication. Further Biofilter analysis of all replicating models revealed a number of common functions among the genes harboring the 83 replicating SNP-SNP models, which included signal transduction and PI3K-Akt signaling pathway. These findings demonstrate the utility of Biofilter as a biology-driven method, applicable for any genome-wide association study dataset.
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Affiliation(s)
- Molly A Hall
- Department of Biochemistry and Molecular Biology, Center for Systems Genomics, Eberly College of Science, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Shefali S Verma
- Department of Biochemistry and Molecular Biology, Center for Systems Genomics, Eberly College of Science, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - John Wallace
- Department of Biochemistry and Molecular Biology, Center for Systems Genomics, Eberly College of Science, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Anastasia Lucas
- Department of Biochemistry and Molecular Biology, Center for Systems Genomics, Eberly College of Science, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Richard L Berg
- Marshfield Clinic, Marshfield, Wisconsin, United States of America
| | - John Connolly
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Dana C Crawford
- Department of Epidemiology and Biostatistics, Institute for Computational Biology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - David R Crosslin
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | | | - Kimberly F Doheny
- Center for Inherited Disease Research, IGM, Johns Hopkins University SOM, Baltimore, Maryland, United States of America
| | - Jonathan L Haines
- Department of Epidemiology and Biostatistics, Institute for Computational Biology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - John B Harley
- Department of Pediatrics, Cincinnati Children's Hospital, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Gail P Jarvik
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America.,Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Terrie Kitchner
- Marshfield Clinic, Marshfield, Wisconsin, United States of America
| | - Helena Kuivaniemi
- Geisinger Health System, Danville, Pennsylvania, United States of America
| | - Eric B Larson
- Group Health Research Institute, Seattle, Washington, United States of America
| | - David S Carrell
- Group Health Research Institute, Seattle, Washington, United States of America
| | - Gerard Tromp
- Geisinger Health System, Danville, Pennsylvania, United States of America
| | - Tamara R Vrabec
- Geisinger Health System, Danville, Pennsylvania, United States of America
| | | | | | - Marylyn D Ritchie
- Department of Biochemistry and Molecular Biology, Center for Systems Genomics, Eberly College of Science, The Pennsylvania State University, University Park, Pennsylvania, United States of America.,Geisinger Health System, Danville, Pennsylvania, United States of America
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Chen YS, Green CR, Danesh-Meyer HV, Rupenthal ID. Neuroprotection in the treatment of glaucoma--A focus on connexin43 gap junction channel blockers. Eur J Pharm Biopharm 2015; 95:182-93. [PMID: 25676338 DOI: 10.1016/j.ejpb.2015.01.031] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 12/23/2014] [Accepted: 01/07/2015] [Indexed: 01/01/2023]
Abstract
Glaucoma is a form of optic neuropathy and a common cause of blindness, affecting over 60 million people worldwide with an expected rise to 80 million by 2020. Successful treatment is challenging due to the various causes of glaucoma, undetectable symptoms at an early stage and inefficient delivery of drugs to the back of the eye. Conventional glaucoma treatments focus on the reduction of elevated intraocular pressure (IOP) using topical eye drops. However, their efficacy is limited to patients who suffer from high IOP glaucoma and do not address the underlying susceptibility of retinal ganglion cells (RGC) to degeneration. Glaucoma is known as a neurodegenerative disease which starts with RGC death and eventually results in damage of the optic nerve. Neuroprotective strategies therefore offer a novel treatment option for glaucoma by not only preventing neuronal loss but also disease progression. This review firstly gives an overview of the pathophysiology of glaucoma as well as current treatment options including conventional and novel delivery strategies. It then summarizes the rational for neuroprotection as a novel therapy for glaucomatous neuropathies and reviews current potential neuroprotective strategies to preserve RGC, with a focus on connexin43 (Cx43) gap junction channel blockers.
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Affiliation(s)
- Ying-Shan Chen
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Helen V Danesh-Meyer
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
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Nishii K, Shibata Y, Kobayashi Y. Connexin mutant embryonic stem cells and human diseases. World J Stem Cells 2014; 6:571-578. [PMID: 25426253 PMCID: PMC4178256 DOI: 10.4252/wjsc.v6.i5.571] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 09/11/2014] [Accepted: 09/17/2014] [Indexed: 02/06/2023] Open
Abstract
Intercellular communication via gap junctions allows cells within multicellular organisms to share small molecules. The effect of such interactions has been elucidated using mouse gene knockout strategies. Although several mutations in human gap junction-encoding connexin (Cx) have been described, Cx mutants in mice do not always recapitulate the human disease. Among the 20 mouse Cxs, Cx26, Cx43, and Cx45 play roles in early cardiac or placental development, and disruption of the genes results in lethality that hampers further analyses. Embryonic stem cells (ESCs) that lack Cx43 or Cx45 have made analysis feasible in both in vitro differentiated cell cultures and in vivo chimeric tissues. The success of mouse ESCs studies is leading to the use of induced pluripotent stem cells to learn more about the pathogenesis of human Cx diseases. This review summarizes the current status of mouse Cx disruption models and ESC differentiation studies, and discusses their implication for understanding human Cx diseases.
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Jerath NU, Shy ME. Hereditary motor and sensory neuropathies: Understanding molecular pathogenesis could lead to future treatment strategies. Biochim Biophys Acta Mol Basis Dis 2014; 1852:667-78. [PMID: 25108281 DOI: 10.1016/j.bbadis.2014.07.031] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 07/02/2014] [Accepted: 07/30/2014] [Indexed: 10/24/2022]
Abstract
Inherited peripheral neuropathies, like many other degenerative disorders, have been challenging to treat. At this point, there is little specific therapy for the inherited neuropathies other than genetic counseling as well as symptomatic treatment and rehabilitation. In the past, ascorbic acid, progesterone antagonists, and subcutaneous neurotrophin-3 (NT3) injections have demonstrated improvement in animal models of CMT 1A, the most common inherited neuropathy, but have failed to translate any effect in humans. Given the difficulty in treatment, it is important to understand the molecular pathogenesis of hereditary neuropathies in order to strategize potential future therapies. The hereditary neuropathies are in an era of molecular insight and over the past 20 years, more than 78 subtypes of Charcot Marie Tooth disease (CMT) have been identified and extensively studied to understand the biological pathways in greater detail. Next generation molecular sequencing has also improved the diagnosis as well as the understanding of CMT. A greater understanding of the molecular pathways will help pave the way to future therapeutics of CMT. This article is part of a Special Issue entitled: Neuromuscular Diseases: Pathology and Molecular Pathogenesis.
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Affiliation(s)
- Nivedita U Jerath
- University of Iowa, Carver College of Medicine, Department of Neurology, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Michael E Shy
- University of Iowa, Carver College of Medicine, Department of Neurology, 200 Hawkins Drive, Iowa City, IA 52242, USA.
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37
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Cai C, Zhao D, Ma C, Zhang Y, Wu X, Wei G, He D. Connexin 43 expression in Sprague-Dawley rat seminiferous epithelium afterin uteroexposure to flutamide. Syst Biol Reprod Med 2014; 60:257-62. [DOI: 10.3109/19396368.2014.921738] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Solan JL, Lampe PD. Specific Cx43 phosphorylation events regulate gap junction turnover in vivo. FEBS Lett 2014; 588:1423-9. [PMID: 24508467 DOI: 10.1016/j.febslet.2014.01.049] [Citation(s) in RCA: 188] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 01/28/2014] [Accepted: 01/28/2014] [Indexed: 10/25/2022]
Abstract
Gap junctions, composed of proteins from the connexin gene family, are highly dynamic structures that are regulated by kinase-mediated signaling pathways and interactions with other proteins. Phosphorylation of Connexin43 (Cx43) at different sites controls gap junction assembly, gap junction size and gap junction turnover. Here we present a model describing how Akt, mitogen activated protein kinase (MAPK) and src kinase coordinate to regulate rapid turnover of gap junctions. Specifically, Akt phosphorylates Cx43 at S373 eliminating interaction with zona occludens-1 (ZO-1) allowing gap junctions to enlarge. Then MAPK and src phosphorylate Cx43 to initiate turnover. We integrate published data with new data to test and refine this model. Finally, we propose that differential coordination of kinase activation and Cx43 phosphorylation controls the specific routes of disassembly, e.g., annular junction formation or gap junctions can potentially "unzip" and be internalized/endocytosed into the cell that produced each connexin.
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Affiliation(s)
- Joell L Solan
- Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, United States
| | - Paul D Lampe
- Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, United States.
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39
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CIP75 (connexin43-interacting protein of 75 kDa) mediates the endoplasmic reticulum dislocation of connexin43. Biochem J 2014; 458:57-67. [DOI: 10.1042/bj20131247] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The proteasomal degradation of the gap junction protein connexin43 is facilitated by its interaction with the connexin43-interacting protein of 75 kDa at the endoplasmic reticulum membrane.
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40
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Connexins: mechanisms regulating protein levels and intercellular communication. FEBS Lett 2014; 588:1212-20. [PMID: 24457202 DOI: 10.1016/j.febslet.2014.01.013] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 01/10/2014] [Accepted: 01/13/2014] [Indexed: 11/21/2022]
Abstract
Intercellular communication can occur through gap junction channels, which are comprised of connexin proteins. Therefore, levels of connexins can directly correlate with gap junctional intercellular communication. Because gap junctions have a critical role in maintaining cellular homeostasis, the regulation of connexin protein levels is important. In the connexin life cycle, connexin protein levels can be modified through differential gene transcription or altered through trafficking and degradation mechanisms. More recently, significant attention has been directed to the pathways that cells utilize to increase or decrease connexin levels and thus indirectly, gap junctional communication. Here, we review the studies revealing the mechanisms that affect connexin protein levels and gap junctional intercellular communication.
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41
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Nielsen MS, Axelsen LN, Sorgen PL, Verma V, Delmar M, Holstein-Rathlou NH. Gap junctions. Compr Physiol 2013; 2:1981-2035. [PMID: 23723031 DOI: 10.1002/cphy.c110051] [Citation(s) in RCA: 298] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease.
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Affiliation(s)
- Morten Schak Nielsen
- Department of Biomedical Sciences and The Danish National Research Foundation Centre for Cardiac Arrhythmia, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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Pérez-Armendariz EM. Connexin 36, a key element in pancreatic beta cell function. Neuropharmacology 2013; 75:557-66. [PMID: 23973309 DOI: 10.1016/j.neuropharm.2013.08.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 08/05/2013] [Accepted: 08/07/2013] [Indexed: 12/01/2022]
Abstract
The prevalence of diabetes at a global scale has markedly increased during the last three decades. Diabetes is a chronic disease that includes a group of metabolic disorders, in which high serum glucose levels is a common factor. Insulin is the only hormone that decreases serum glucose levels. Therefore, it is relevant to deepen our understanding of cell mechanisms that regulate insulin production and release. Insulin is produced in pancreatic islet beta cells. They are excitable cells and most of them are electrically coupled through gap junction channels. Connexin 36 (Cx36) has been identified at junctional membranes of islet beta cells in both rodents and humans. Co-localization of Cx36 with Cx30.2 has been recently identified. Functional studies in Cx36 deficient mice have provided direct evidence that Cx36 gap junction channels are necessary for the synchronization of [Ca(2+)]i oscillations in islet beta cells. The latter allows for the generation of insulin pulses in a single perfused islet. Moreover, Cx36 deficient mice were found to have altered serum insulin pulse dynamics and to be glucose intolerant. In addition, Cx36 has been recently identified as an early gene that is specifically expressed in embryonic beta cells, whose transcript and protein are upregulated in unison with the main wave of beta cell differentiation. In conclusion, Cx36 is critical for endocrine pancreatic function and may represent a molecular target for future prevention and treatment of diabetes. This article is part of the Special Issue Section entitled 'Current Pharmacology of Gap Junction Channels and Hemichannels'.
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Affiliation(s)
- E Martha Pérez-Armendariz
- Unidad de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Torre de Investigación 5to piso, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, UNAM, México D.F. 04510, Mexico; Hospital General de México, Hospital General de México/Unidad de Medicina Experimental, Facultad de Medicina, UNAM, Dr Balmis 148, Colonia Doctores, Delegación Cuahutémoc, CP 06726 Ciudad de México, Mexico; Departamento of Biología Celular yTisular, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Circuito Interior, Ciudad Universitaria, UNAM, Mexico D.F. 04510, Mexico.
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Kleopa KA, Sargiannidou I, Markoullis K. Connexin pathology in chronic multiple sclerosis and experimental autoimmune encephalomyelitis. ACTA ACUST UNITED AC 2013. [DOI: 10.1111/cen3.12055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Kleopas A. Kleopa
- Neurology Clinics and Neuroscience Laboratory; The Cyprus Institute of Neurology and Genetics; Nicosia Cyprus
| | - Irene Sargiannidou
- Neurology Clinics and Neuroscience Laboratory; The Cyprus Institute of Neurology and Genetics; Nicosia Cyprus
| | - Kyriaki Markoullis
- Neurology Clinics and Neuroscience Laboratory; The Cyprus Institute of Neurology and Genetics; Nicosia Cyprus
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Jiang T, Long H, Ma Y, Long L, Li Y, Li F, Zhou P, Yuan C, Xiao B. Altered expression of pannexin proteins in patients with temporal lobe epilepsy. Mol Med Rep 2013; 8:1801-6. [PMID: 24146091 DOI: 10.3892/mmr.2013.1739] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 10/07/2013] [Indexed: 11/06/2022] Open
Abstract
The aim of the present study was to investigate the expression of the pannexin (Panx) proteins, Panx1 and Panx2, in the temporal lobe tissue of patients with temporal lobe epilepsy (TLE). Immunohistochemistry and western blotting methods were used to localize and quantify Panx1 and Panx2 in the surgically removed brain tissue of patients with TLE (n=37). The results were then compared with non-epileptogenic controls (n=9). Panx1 and Panx2 expression was detected in the temporal lobe cortex of patients with TLE and in the control tissues. Panx1 and Panx2 proteins were expressed in all layers of the epileptic cortex, but predominantly in layers II and III of the cortex in the control group. Panx1 protein expression was significantly higher in the temporal lobe cortex of the patients with TLE than in the controls (P<0.05; t-test); however, no significant differences were identified in the Panx2 expression levels between the patients and the controls (P>0.05; t-test). The expression of the two Panx proteins in the tissue layers of the epileptic cortex varied in the patients and controls. The results indicate that Panx channels may be involved in the pathogenesis of TLE.
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Affiliation(s)
- Ting Jiang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
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Coronel-Cruz C, Hernández-Tellez B, López-Vancell R, López-Vidal Y, Berumen J, Castell A, Pérez-Armendariz EM. Connexin 30.2 is expressed in mouse pancreatic beta cells. Biochem Biophys Res Commun 2013; 438:772-7. [PMID: 23831630 DOI: 10.1016/j.bbrc.2013.06.100] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 06/25/2013] [Indexed: 12/13/2022]
Abstract
Nowadays, connexin (Cx) 36 is considered the sole gap junction protein expressed in pancreatic beta cells. In the present research we investigated the expression of Cx30.2 mRNA and protein in mouse pancreatic islets. Cx30.2 mRNA and protein were identified in isolated islet preparations by qRT-PCR and Western blot, respectively. Immunohistochemical analysis showed that insulin-positive cells were stained for Cx30.2. Confocal images from double-labeled pancreatic sections revealed that Cx30.2 and Cx36 fluorescence co-localize at junctional membranes in islets from most pancreases. Abundant Cx30.2 tiny reactive spots were also found in cell cytoplasms. In beta cells cultured with stimulatory glucose concentrations, Cx30.2 was localized in both cytoplasms and cell membranes. In addition, Cx30.2 reactivity was localized at junctional membranes of endothelial or cluster of differentiation 31 (CD31) positive cells. Moreover, a significant reduction of Cx30.2 mRNA was found in islets preparations incubated for 24h in 22mM as compared with 3.3mM glucose. Therefore, it is concluded that Cx30.2 is expressed in beta and vascular endothelial cells of mouse pancreatic islets.
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Affiliation(s)
- C Coronel-Cruz
- Unidad de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, México, DF 04510, México
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Holcroft CE, Jackson WD, Lin WH, Bassiri K, Baines RA, Phelan P. Innexins Ogre and Inx2 are required in glial cells for normal postembryonic development of the Drosophila central nervous system. J Cell Sci 2013; 126:3823-34. [PMID: 23813964 DOI: 10.1242/jcs.117994] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Innexins are one of two gene families that have evolved to permit neighbouring cells in multicellular systems to communicate directly. Innexins are found in prechordates and persist in small numbers in chordates as divergent sequences termed pannexins. Connexins are functionally analogous proteins exclusive to chordates. Members of these two families of proteins form intercellular channels, assemblies of which constitute gap junctions. Each intercellular channel is a composite of two hemichannels, one from each of two apposed cells. Hemichannels dock in the extracellular space to form a complete channel with a central aqueous pore that regulates the cell-cell exchange of ions and small signalling molecules. Hemichannels can also act independently by releasing paracrine signalling molecules. optic ganglion reduced (ogre) is a member of the Drosophila innexin family, originally identified as a gene essential for postembryonic neurogenesis. Here we demonstrate, by heterologous expression in paired Xenopus oocytes, that Ogre alone does not form homotypic gap-junction channels; however, co-expression of Ogre with Innexin2 (Inx2) induces formation of functional channels with properties distinct from Inx2 homotypic channels. In the Drosophila larval central nervous system, we find that Inx2 partially colocalises with Ogre in proliferative neuroepithelia and in glial cells. Downregulation of either ogre or inx2 selectively in glia, by targeted expression of RNA interference transgenes, leads to a significant reduction in the size of the larval nervous system and behavioural defects in surviving adults. We conclude that these innexins are crucially required in glial cells for normal postembryonic development of the central nervous system.
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Endothelial control of vasodilation: integration of myoendothelial microdomain signalling and modulation by epoxyeicosatrienoic acids. Pflugers Arch 2013; 466:389-405. [PMID: 23748495 DOI: 10.1007/s00424-013-1303-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 05/24/2013] [Accepted: 05/26/2013] [Indexed: 12/17/2022]
Abstract
Endothelium-derived epoxyeicosatrienoic acids (EETs) are fatty acid epoxides that play an important role in the control of vascular tone in selected coronary, renal, carotid, cerebral and skeletal muscle arteries. Vasodilation due to endothelium-dependent smooth muscle hyperpolarization (EDH) has been suggested to involve EETs as a transferable endothelium-derived hyperpolarizing factor. However, this activity may also be due to EETs interacting with the components of other primary EDH-mediated vasodilator mechanisms. Indeed, the transfer of hyperpolarization initiated in the endothelium to the adjacent smooth muscle via gap junction connexins occurs separately or synergistically with the release of K(+) ions at discrete myoendothelial microdomain signalling sites. The net effects of such activity are smooth muscle hyperpolarization, closure of voltage-dependent Ca(2+) channels, phospholipase C deactivation and vasodilation. The spatially localized and key components of the microdomain signalling complex are the inositol 1,4,5-trisphosphate receptor-mediated endoplasmic reticulum Ca(2+) store, Ca(2+)-activated K(+) (KCa), transient receptor potential (TRP) and inward-rectifying K(+) channels, gap junctions and the smooth muscle Na(+)/K(+)-ATPase. Of these, TRP channels and connexins are key endothelial effector targets modulated by EETs. In an integrated manner, endogenous EETs enhance extracellular Ca(2+) influx (thereby amplifying and prolonging KCa-mediated endothelial hyperpolarization) and also facilitate the conduction of this hyperpolarization to spatially remote vessel regions. The contribution of EETs and the receptor and channel subtypes involved in EDH-related microdomain signalling, as a candidate for a universal EDH-mediated vasodilator mechanism, vary with vascular bed, species, development and disease and thus represent potentially selective targets for modulating specific artery function.
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Role of p63 and the Notch pathway in cochlea development and sensorineural deafness. Proc Natl Acad Sci U S A 2013; 110:7300-5. [PMID: 23589895 DOI: 10.1073/pnas.1214498110] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ectodermal dysplasias are a group of inherited autosomal dominant syndromes associated with heterozygous mutations in the Tumor Protein p63 (TRP63) gene. Here we show that, in addition to their epidermal pathology, a proportion of these patients have distinct levels of deafness. Accordingly, p63 null mouse embryos show marked cochlea abnormalities, and the transactivating isoform of p63 (TAp63) protein is normally found in the organ of Corti. TAp63 transactivates hairy and enhancer of split 5 (Hes5) and atonal homolog 1 (Atoh1), components of the Notch pathway, known to be involved in cochlear neuroepithelial development. Strikingly, p63 null mice show morphological defects of the organ of Corti, with supernumerary hair cells, as also reported for Hes5 null mice. This phenotype is related to loss of a differentiation property of TAp63 and not to loss of its proapoptotic function, because cochleas in mice lacking the critical Bcl-2 homology domain (BH-3) inducers of p53- and p63-mediated apoptosis--Puma, Noxa, or both--are normal. Collectively, these data demonstrate that TAp63, acting via the Notch pathway, is crucial for the development of the organ of Corti, providing a molecular explanation for the sensorineural deafness in ectodermal dysplasia patients with TRP63 mutations.
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Chang HM, Cheng JC, Leung PCK. Theca-derived BMP4 and BMP7 down-regulate connexin43 expression and decrease gap junction intercellular communication activity in immortalized human granulosa cells. J Clin Endocrinol Metab 2013; 98:E437-45. [PMID: 23386650 DOI: 10.1210/jc.2012-3851] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
CONTEXT Connexin43 (Cx43)-coupled gap junctions in granulosa cells play important roles in follicular and oocyte development and may be modulated by theca cell-derived bone morphogenic protein (BMP) 4 and BMP7. OBJECTIVE The aim of this study was to examine the effects of BMP4 and BMP7 on Cx43 expression in human granulosa cells and its potential mediation by the Smad-dependent pathway. DESIGN An immortalized human granulosa (SVOG) cell was used to investigate Cx43 expression and gap junction intercellular communication (GJIC) activity after exposure to BMP4 and BMP7. A BMP type I inhibitor, dorsomorphin, and small interfering RNAs targeting Smad4 were used to verify the specificity of the effects. SETTING The study was conducted in an academic center. MAIN OUTCOME MEASURES Extracts were prepared from cultured cells, the Cx43 mRNA levels were examined using RT-quantitative real-time PCR, and the levels of Cx43 protein and phosphorylated Smad1/5/8 were assayed using Western blot analyses. GJIC activities between SVOG cells were evaluated using a scrape loading and dye transfer assay. RESULTS Treatment with BMP4 and BMP7 significantly decreased Cx43 mRNA and protein levels, as well as GJIC activities. These suppressive effects were attenuated by cotreatment with the BMP type I receptor inhibitor dorsomorphin. Furthermore, Smad4 knockdown reversed the effects of BMP4 and BMP7 on Cx43 expression. CONCLUSION Theca cell-derived BMP4 and BMP7 down-regulate Cx43 expression and decrease GJIC activity in human granulosa cells. Our findings indicate that this biological effect is most likely mediated by a Smad-dependent pathway.
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Affiliation(s)
- Hsun-Ming Chang
- Department of Obstetrics and Gynaecology, Child and Family Research Institute, University of British Columbia, Room 317, 950 West 28th Avenue, Vancouver, British Columbia, Canada
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Mhaske PV, Levit NA, Li L, Wang HZ, Lee JR, Shuja Z, Brink PR, White TW. The human Cx26-D50A and Cx26-A88V mutations causing keratitis-ichthyosis-deafness syndrome display increased hemichannel activity. Am J Physiol Cell Physiol 2013; 304:C1150-8. [PMID: 23447037 DOI: 10.1152/ajpcell.00374.2012] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Mutations in the human gene encoding connexin 26 (Cx26 or GJB2) cause either nonsyndromic deafness or syndromic deafness associated with skin diseases. That distinct clinical disorders can be caused by different mutations within the same gene suggests that different channel activities influence the ear and skin. Here we use three different expression systems to examine the functional characteristics of two Cx26 mutations causing either mild (Cx26-D50A) or lethal (Cx26-A88V) keratitis-ichthyosis-deafness (KID) syndrome. In either cRNA-injected Xenopus oocytes, transfected HeLa cells, or transfected primary human keratinocytes, we show that both Cx26-D50A and Cx26-A88V form active hemichannels that significantly increase membrane current flow compared with wild-type Cx26. This increased membrane current accelerated cell death in low extracellular calcium solutions and was not due to increased mutant protein expression. Elevated mutant hemichannel currents could be blocked by increased extracellular calcium concentration. These results show that these two mutations exhibit a shared gain of functional activity and support the hypothesis that increased hemichannel activity is a common feature of human Cx26 mutations responsible for KID syndrome.
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Affiliation(s)
- Pallavi V Mhaske
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794, USA
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