1
|
Bayraktar E, Lopez-Pigozzi D, Bortolozzi M. Calcium Regulation of Connexin Hemichannels. Int J Mol Sci 2024; 25:6594. [PMID: 38928300 PMCID: PMC11204158 DOI: 10.3390/ijms25126594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 06/07/2024] [Accepted: 06/12/2024] [Indexed: 06/28/2024] Open
Abstract
Connexin hemichannels (HCs) expressed at the plasma membrane of mammalian cells are of paramount importance for intercellular communication. In physiological conditions, HCs can form gap junction (GJ) channels, providing a direct diffusive path between neighbouring cells. In addition, unpaired HCs provide conduits for the exchange of solutes between the cytoplasm and the extracellular milieu, including messenger molecules involved in paracrine signalling. The synergistic action of membrane potential and Ca2+ ions controls the gating of the large and relatively unselective pore of connexin HCs. The four orders of magnitude difference in gating sensitivity to the extracellular ([Ca2+]e) and the cytosolic ([Ca2+]c) Ca2+ concentrations suggests that at least two different Ca2+ sensors may exist. While [Ca2+]e acts as a spatial modulator of the HC opening, which is most likely dependent on the cell layer, compartment, and organ, [Ca2+]c triggers HC opening and the release of extracellular bursts of messenger molecules. Such molecules include ATP, cAMP, glutamate, NAD+, glutathione, D-serine, and prostaglandins. Lost or abnormal HC regulation by Ca2+ has been associated with several diseases, including deafness, keratitis ichthyosis, palmoplantar keratoderma, Charcot-Marie-Tooth neuropathy, oculodentodigital dysplasia, and congenital cataracts. The fact that both an increased and a decreased Ca2+ sensitivity has been linked to pathological conditions suggests that Ca2+ in healthy cells finely tunes the normal HC function. Overall, further investigation is needed to clarify the structural and chemical modifications of connexin HCs during [Ca2+]e and [Ca2+]c variations. A molecular model that accounts for changes in both Ca2+ and the transmembrane voltage will undoubtedly enhance our interpretation of the experimental results and pave the way for developing therapeutic compounds targeting specific HC dysfunctions.
Collapse
Affiliation(s)
- Erva Bayraktar
- Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Via Marzolo 8, 35131 Padova, Italy
| | - Diego Lopez-Pigozzi
- Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Via Marzolo 8, 35131 Padova, Italy
| | - Mario Bortolozzi
- Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Via Marzolo 8, 35131 Padova, Italy
- Institute of Endocrinology and Oncology “Gaetano Salvatore” (IEOS-CNR), Via Pietro Castellino 111, 80131 Napoli, Italy
| |
Collapse
|
2
|
Li E, van der Heyden MAG. The network of cardiac K IR2.1: its function, cellular regulation, electrical signaling, diseases and new drug avenues. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024:10.1007/s00210-024-03116-5. [PMID: 38683369 DOI: 10.1007/s00210-024-03116-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 04/19/2024] [Indexed: 05/01/2024]
Abstract
The functioning of the human heart relies on complex electrical and communication systems that coordinate cardiac contractions and sustain rhythmicity. One of the key players contributing to this intricate system is the KIR2.1 potassium ion channel, which is encoded by the KCNJ2 gene. KIR2.1 channels exhibit abundant expression in both ventricular myocytes and Purkinje fibers, exerting an important role in maintaining the balance of intracellular potassium ion levels within the heart. And by stabilizing the resting membrane potential and contributing to action potential repolarization, these channels have an important role in cardiac excitability also. Either gain- or loss-of-function mutations, but also acquired impairments of their function, are implicated in the pathogenesis of diverse types of cardiac arrhythmias. In this review, we aim to elucidate the system functions of KIR2.1 channels related to cellular electrical signaling, communication, and their contributions to cardiovascular disease. Based on this knowledge, we will discuss existing and new pharmacological avenues to modulate their function.
Collapse
Affiliation(s)
- Encan Li
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, Netherlands
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, Netherlands.
| |
Collapse
|
3
|
Bruss P, Hartle R, Astacio J, Chauhdri AF. Electrocardiographic Effects of Bupropion Toxicity Suggesting Dysfunction of the Gap Junction or Connexin 43. Cureus 2024; 16:e56288. [PMID: 38623136 PMCID: PMC11018313 DOI: 10.7759/cureus.56288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/16/2024] [Indexed: 04/17/2024] Open
Abstract
This is a case of a 20-year-old pregnant female presenting EKG abnormalities associated with an overdose of bupropion. These ECG abnormalities are prolongation of the QRS, prolongation of the corrected QT interval (QTc), right axis deviation, and a terminal R wave. The propagation of electricity through the myocardium is dependent on many factors. It is dependent on the flow of sodium from the extracellular to intracellular space, flow of potassium from intracellular to extracellular space, and ultimately the propagation of the signal at the gap junction by Connexin 43 (Cx-43). We postulate that the ECG abnormalities in this case are secondary to bupropion's effect on the potassium rectifier channels (Kir) and or Cx-43 at the gap junction.
Collapse
Affiliation(s)
- Patrick Bruss
- Emergency Medicine, ProMedica Monroe Regional Hospital, Monroe, USA
| | - Ryan Hartle
- Emergency Medicine, ProMedica Monroe Regional Hospital, Monroe, USA
| | - Jennifer Astacio
- Emergency Medicine, ProMedica Monroe Regional Hospital, Monroe, USA
| | | |
Collapse
|
4
|
Eitelmann S, Everaerts K, Petersilie L, Rose CR, Stephan J. Ca 2+-dependent rapid uncoupling of astrocytes upon brief metabolic stress. Front Cell Neurosci 2023; 17:1151608. [PMID: 37886111 PMCID: PMC10598858 DOI: 10.3389/fncel.2023.1151608] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 08/23/2023] [Indexed: 10/28/2023] Open
Abstract
Astrocytic gap junctional coupling is a major element in neuron-glia interaction. There is strong evidence that impaired coupling is involved in neurological disorders. Reduced coupling was, e.g., demonstrated for core regions of ischemic stroke that suffer from massive cell death. In the surrounding penumbra, cells may recover, but recovery is hampered by spreading depolarizations, which impose additional metabolic stress onto the tissue. Spreading depolarizations are characterized by transient breakdown of cellular ion homeostasis, including pH and Ca2+, which might directly affect gap junctional coupling. Here, we exposed acute mouse neocortical tissue slices to brief metabolic stress and examined its effects on the coupling strength between astrocytes. Changes in gap junctional coupling were assessed by recordings of the syncytial isopotentiality. Moreover, quantitative ion imaging was performed in astrocytes to analyze the mechanisms triggering the observed changes. Our experiments show that a 2-minute perfusion of tissue slices with blockers of glycolysis and oxidative phosphorylation causes a rapid uncoupling in half of the recorded cells. They further indicate that uncoupling is not mediated by the accompanying (moderate) intracellular acidification. Dampening large astrocytic Ca2+ loads by removal of extracellular Ca2+ or blocking Ca2+ influx pathways as well as a pharmacological inhibition of calmodulin, however, prevent the uncoupling. Taken together, we conclude that astrocytes exposed to brief episodes of metabolic stress can undergo a rapid, Ca2+/calmodulin-dependent uncoupling. Such uncoupling may help to confine and reduce cellular damage in the ischemic penumbra in vivo.
Collapse
Affiliation(s)
| | | | | | - Christine R. Rose
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Jonathan Stephan
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| |
Collapse
|
5
|
Tien TY, Wu YJ, Su CH, Hsieh CL, Wang BJ, Lee YN, Su Y, Yeh HI. Pannexin 1 Modulates Angiogenic Activities of Human Endothelial Colony-Forming Cells Through IGF-1 Mechanism and Is a Marker of Senescence. Arterioscler Thromb Vasc Biol 2023; 43:1935-1951. [PMID: 37589139 DOI: 10.1161/atvbaha.123.319529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 08/01/2023] [Indexed: 08/18/2023]
Abstract
BACKGROUND We examined the role of Panxs (pannexins) in human endothelial progenitor cell (EPC) senescence. METHODS Young and replication-induced senescent endothelial colony-forming cells (ECFCs) derived from human circulating EPCs were used to examine cellular activities and senescence-associated indicators after transfection of short interference RNA specific to Panx1 or lentivirus-mediated Panx1 overexpression. Hind limb ischemia mice were used as in vivo angiogenesis model. Protein and phospho-kinase arrays were used to determine underlying mechanisms. RESULTS Panx1 was the predominant Panx isoform in human ECFCs and upregulated in both replication-induced senescent ECFCs and circulating EPCs from aged mice and humans. Cellular activities of the young ECFCs were enhanced by Panx1 downregulation but attenuated by its upregulation. In addition, reduction of Panx1 in the senescent ECFCs could rejuvenate cellular activities with reduced senescence-associated indicators, including senescence-associated β-galactosidase activity, p16INK4a (cyclin-dependent kinase inhibitor 2A), p21 (cyclin-dependent kinase inhibitor 1), acetyl-p53 (tumor protein P53), and phospho-histone H2A.X (histone family member X). In mouse ischemic hind limbs injected senescent ECFCs, blood perfusion ratio, salvaged limb outcome, and capillary density were all improved by Panx1 knockdown. IGF-1 (insulin-like growth factor 1) was significantly increased in the supernatant from senescent ECFCs after Panx1 knockdown. The enhanced activities and paracrine effects of Panx1 knockdown senescent ECFCs were completely inhibited by anti-IGF-1 antibodies. FAK (focal adhesion kinase), ERK (extracellular signal-regulated kinase), and STAT3 (signal transducer and activator of transcription 3) were activated in senescent ECFCs with Panx1 knockdown, in which the intracellular calcium level was reduced, and the activation was inhibited by supplemented calcium. The increased IGF-1 in Panx1-knockdown ECFCs was abrogated, respectively, by inhibitors of FAK (PF562271), ERK (U0126), and STAT3 (NSC74859) and supplemented calcium. CONCLUSIONS Panx1 expression is upregulated in human ECFCs/EPCs with replication-induced senescence and during aging. Angiogenic potential of senescent ECFCs is improved by Panx1 reduction through increased IGF-1 production via activation of the FAK-ERK axis following calcium influx reduction. Our findings provide new strategies to evaluate EPC activities and rejuvenate senescent EPCs for therapeutic angiogenesis.
Collapse
Affiliation(s)
- Ting-Yi Tien
- Institute of Biopharmaceutical Science, National Yang Ming Chiao Tung University, Taipei, Taiwan (T.-Y.T., Y.S.)
- Departments of Medical Research (T.-Y.T., C.-L.H., B.-J.W., Y.-N.L.), MacKay Memorial Hospital, Taipei, Taiwan
| | - Yih-Jer Wu
- Internal Medicine (Y.-J.W., C.-H.S., H.-I.Y.), MacKay Memorial Hospital, Taipei, Taiwan
- Department of Medicine, MacKay Medical College, New Taipei City, Taiwan (Y.-J.W., C.-H.S., H.-I.Y.)
| | - Cheng-Huang Su
- Internal Medicine (Y.-J.W., C.-H.S., H.-I.Y.), MacKay Memorial Hospital, Taipei, Taiwan
- Department of Medicine, MacKay Medical College, New Taipei City, Taiwan (Y.-J.W., C.-H.S., H.-I.Y.)
| | - Chin-Ling Hsieh
- Departments of Medical Research (T.-Y.T., C.-L.H., B.-J.W., Y.-N.L.), MacKay Memorial Hospital, Taipei, Taiwan
| | - Bo-Jeng Wang
- Departments of Medical Research (T.-Y.T., C.-L.H., B.-J.W., Y.-N.L.), MacKay Memorial Hospital, Taipei, Taiwan
| | - Yi-Nan Lee
- Departments of Medical Research (T.-Y.T., C.-L.H., B.-J.W., Y.-N.L.), MacKay Memorial Hospital, Taipei, Taiwan
| | - Yeu Su
- Institute of Biopharmaceutical Science, National Yang Ming Chiao Tung University, Taipei, Taiwan (T.-Y.T., Y.S.)
| | - Hung-I Yeh
- Internal Medicine (Y.-J.W., C.-H.S., H.-I.Y.), MacKay Memorial Hospital, Taipei, Taiwan
- Department of Medicine, MacKay Medical College, New Taipei City, Taiwan (Y.-J.W., C.-H.S., H.-I.Y.)
| |
Collapse
|
6
|
Jovanovic M, Mitra A, Besio R, Contento BM, Wong KW, Derkyi A, To M, Forlino A, Dale RK, Marini JC. Absence of TRIC-B from type XIV Osteogenesis Imperfecta osteoblasts alters cell adhesion and mitochondrial function - A multi-omics study. Matrix Biol 2023; 121:127-148. [PMID: 37348683 PMCID: PMC10634967 DOI: 10.1016/j.matbio.2023.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/06/2023] [Accepted: 06/16/2023] [Indexed: 06/24/2023]
Abstract
Osteogenesis Imperfecta (OI) is a heritable collagen-related bone dysplasia characterized by bone fractures, growth deficiency and skeletal deformity. Type XIV OI is a recessive OI form caused by null mutations in TMEM38B, which encodes the ER membrane intracellular cation channel TRIC-B. Previously, we showed that absence of TMEM38B alters calcium flux in the ER of OI patient osteoblasts and fibroblasts, which further disrupts collagen synthesis and secretion. How the absence of TMEM38B affects osteoblast function is still poorly understood. Here we further investigated the role of TMEM38B in human osteoblast differentiation and mineralization. TMEM38B-null osteoblasts showed altered expression of osteoblast marker genes and decreased mineralization. RNA-Seq analysis revealed that cell-cell adhesion was one of the most downregulated pathways in TMEM38B-null osteoblasts, with further validation by real-time PCR and Western blot. Gap and tight junction proteins were also decreased by TRIC-B absence, both in patient osteoblasts and in calvarial osteoblasts of Tmem38b-null mice. Disrupted cell adhesion decreased mutant cell proliferation and cell cycle progression. An important novel finding was that TMEM38B-null osteoblasts had elongated mitochondria with altered fusion and fission markers, MFN2 and DRP1. In addition, TMEM38B-null osteoblasts exhibited a significant increase in superoxide production in mitochondria, further supporting mitochondrial dysfunction. Together these results emphasize the novel role of TMEM38B/TRIC-B in osteoblast differentiation, affecting cell-cell adhesion processes, gap and tight junction, proliferation, cell cycle, and mitochondrial function.
Collapse
Affiliation(s)
- Milena Jovanovic
- Section on Heritable Disorders of Bone and Extracellular Matrix, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Apratim Mitra
- Bioinformatics and Scientific Programming Core, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Roberta Besio
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | | | - Ka Wai Wong
- Department of Orthopaedics and Traumatology, The University of Hong Kong-Shenzhen Hospital (HKU-SZH), Shenzhen, China; Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Alberta Derkyi
- Office of the Clinical Director, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Michael To
- Department of Orthopaedics and Traumatology, The University of Hong Kong-Shenzhen Hospital (HKU-SZH), Shenzhen, China; Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Antonella Forlino
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Ryan K Dale
- Bioinformatics and Scientific Programming Core, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Joan C Marini
- Section on Heritable Disorders of Bone and Extracellular Matrix, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States.
| |
Collapse
|
7
|
Song MH, Choi SC, Noh JM, Joo HJ, Park CY, Cha JJ, Ahn TH, Ko TH, Choi JI, Na JE, Rhyu IJ, Jang Y, Park Y, Gim JA, Kim JH, Lim DS. LEFTY-PITX2 signaling pathway is critical for generation of mature and ventricular cardiac organoids in human pluripotent stem cell-derived cardiac mesoderm cells. Biomaterials 2021; 278:121133. [PMID: 34571434 DOI: 10.1016/j.biomaterials.2021.121133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 09/10/2021] [Accepted: 09/15/2021] [Indexed: 02/07/2023]
Abstract
The generation of mature ventricular cardiomyocytes (CMs) resembling adult CMs from human pluripotent stem cells (hPSCs) is necessary for disease modeling and drug discovery. To investigate the effect of self-organizing capacity on the generation of mature cardiac organoids (COs), we generated cardiac mesoderm cell-derived COs (CMC-COs) and CM-derived COs (CM-COs) and evaluated COs. CMC-COs exhibited more organized sarcomere structures and mitochondria, well-arranged t-tubule structures, and evenly distributed intercalated discs. Increased expressions of ventricular CM, cardiac metabolic, t-tubule formation, K+ ion channel, and junctional markers were confirmed in CMC-COs. Mature ventricular-like function such as faster motion vector speed, decreased beats per min, increased peak-to-peak duration, and prolonged APD50 and APD90 were observed in CMC-COs. Transcriptional profiling revealed that extracellular matrix-integrin, focal adhesion, and LEFTY-PITX2 signaling pathways are upregulated in CMC-COs. LEFTY knockdown affected ECM-integrin-FA signaling pathways in CMC-COs. Here, we found that high self-organizing capacity of CMCs is critical for the generation of mature and ventricular COs. We also demonstrated that LEFTY-PITX2 signaling plays key roles for CM maturation and specification into ventricular-like CM subtype in CMC-COs. CMC-COs are an attractive resource for disease modeling and drug discovery.
Collapse
Affiliation(s)
- Myeong-Hwa Song
- Department of Cardiology, Cardiovascular Center, College of Medicine, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, South Korea
| | - Seung-Cheol Choi
- Department of Cardiology, Cardiovascular Center, College of Medicine, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, South Korea; R&D Center for Companion Diagnostic, SOL Bio Corporation, Suite 510, 27, Seongsui-ro7-gil, Seongdong-gu, Seoul, 04780, South Korea
| | - Ji-Min Noh
- Department of Cardiology, Cardiovascular Center, College of Medicine, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, South Korea
| | - Hyung Joon Joo
- Department of Cardiology, Cardiovascular Center, College of Medicine, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, South Korea
| | - Chi-Yeon Park
- Department of Cardiology, Cardiovascular Center, College of Medicine, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, South Korea
| | - Jung-Joon Cha
- Department of Cardiology, Cardiovascular Center, College of Medicine, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, South Korea
| | - Tae Hoon Ahn
- Department of Cardiology, Cardiovascular Center, College of Medicine, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, South Korea
| | - Tae Hee Ko
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Anam Hospital, Seoul, 02841, South Korea
| | - Jong-Il Choi
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Anam Hospital, Seoul, 02841, South Korea
| | - Ji Eun Na
- Department of Anatomy, College of Medicine, Korea University, Seoul, 02841, South Korea
| | - Im Joo Rhyu
- Department of Anatomy, College of Medicine, Korea University, Seoul, 02841, South Korea
| | - Yongjun Jang
- Department of Biomedical Sciences, College of Medicine, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, South Korea
| | - Yongdoo Park
- Department of Biomedical Sciences, College of Medicine, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, South Korea
| | - Jeong-An Gim
- Medical Science Research Center, College of Medicine, Korea University Guro Hospital, Seoul,08308, South Korea
| | - Jong-Hoon Kim
- Laboratory of Stem Cells and Tissue Regeneration, Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, 02841, South Korea
| | - Do-Sun Lim
- Department of Cardiology, Cardiovascular Center, College of Medicine, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, South Korea.
| |
Collapse
|
8
|
Yamada A, Yoshizaki K, Ishikawa M, Saito K, Chiba Y, Fukumoto E, Hino R, Hoshikawa S, Chiba M, Nakamura T, Iwamoto T, Fukumoto S. Connexin 43-Mediated Gap Junction Communication Regulates Ameloblast Differentiation via ERK1/2 Phosphorylation. Front Physiol 2021; 12:748574. [PMID: 34630166 PMCID: PMC8500398 DOI: 10.3389/fphys.2021.748574] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 08/25/2021] [Indexed: 11/24/2022] Open
Abstract
Connexin 43 (Cx43) is an integral membrane protein that forms gap junction channels. These channels mediate intercellular transport and intracellular signaling to regulate organogenesis. The human disease oculodentodigital dysplasia (ODDD) is caused by mutations in Cx43 and is characterized by skeletal, ocular, and dental abnormalities including amelogenesis imperfecta. To clarify the role of Cx43 in amelogenesis, we examined the expression and function of Cx43 in tooth development. Single-cell RNA-seq analysis and immunostaining showed that Cx43 is highly expressed in pre-secretory ameloblasts, differentiated ameloblasts, and odontoblasts. Further, we investigated the pathogenic mechanisms of ODDD by analyzing Cx43-null mice. These mice developed abnormal teeth with multiple dental epithelium layers. The expression of enamel matrix proteins such as ameloblastin (Ambn), which is critical for enamel formation, was significantly reduced in Cx43-null mice. TGF-β1 induces Ambn transcription in dental epithelial cells. The induction of Ambn expression by TGF-β1 depends on the density of the cultured cells. Cell culture at low densities reduces cell–cell contact and reduces the effect of TGF-β1 on Ambn induction. When cell density was high, Ambn expression by TGF-β1 was enhanced. This induction was inhibited by the gap junction inhibitors, oleamide, and 18α-grycyrrhizic acid and was also inhibited in cells expressing Cx43 mutations (R76S and R202H). TGF-β1-mediated phosphorylation and nuclear translocation of ERK1/2, but not Smad2/3, were suppressed by gap junction inhibitors. Cx43 gap junction activity is required for TGF-β1-mediated Runx2 phosphorylation through ERK1/2, which forms complexes with Smad2/3. In addition to its gap junction activity, Cx43 may also function as a Ca2+ channel that regulates slow Ca2+ influx and ERK1/2 phosphorylation. TGF-β1 transiently increases intracellular calcium levels, and the increase in intracellular calcium over a short period was not related to the expression level of Cx43. However, long-term intracellular calcium elevation was enhanced in cells overexpressing Cx43. Our results suggest that Cx43 regulates intercellular communication through gap junction activity by modulating TGF-β1-mediated ERK signaling and enamel formation.
Collapse
Affiliation(s)
- Aya Yamada
- Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Keigo Yoshizaki
- Section of Orthodontics and Dentofacial Orthopedics, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Masaki Ishikawa
- The Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
| | - Kan Saito
- Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Yuta Chiba
- Section of Oral Medicine for Children, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Emiko Fukumoto
- Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Ryoko Hino
- Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Seira Hoshikawa
- Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Mitsuki Chiba
- Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Takashi Nakamura
- Division of Molecular Pharmacology and Cell Biophysics, Department of Oral Biology, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Tsutomu Iwamoto
- Division of Oral Health Science, Department of Pediatric Dentistry/Special Needs Dentistry, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, Tokyo, Japan
| | - Satoshi Fukumoto
- Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan.,Section of Oral Medicine for Children, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| |
Collapse
|
9
|
Connexins in the Heart: Regulation, Function and Involvement in Cardiac Disease. Int J Mol Sci 2021; 22:ijms22094413. [PMID: 33922534 PMCID: PMC8122935 DOI: 10.3390/ijms22094413] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
Connexins are a family of transmembrane proteins that play a key role in cardiac physiology. Gap junctional channels put into contact the cytoplasms of connected cardiomyocytes, allowing the existence of electrical coupling. However, in addition to this fundamental role, connexins are also involved in cardiomyocyte death and survival. Thus, chemical coupling through gap junctions plays a key role in the spreading of injury between connected cells. Moreover, in addition to their involvement in cell-to-cell communication, mounting evidence indicates that connexins have additional gap junction-independent functions. Opening of unopposed hemichannels, located at the lateral surface of cardiomyocytes, may compromise cell homeostasis and may be involved in ischemia/reperfusion injury. In addition, connexins located at non-canonical cell structures, including mitochondria and the nucleus, have been demonstrated to be involved in cardioprotection and in regulation of cell growth and differentiation. In this review, we will provide, first, an overview on connexin biology, including their synthesis and degradation, their regulation and their interactions. Then, we will conduct an in-depth examination of the role of connexins in cardiac pathophysiology, including new findings regarding their involvement in myocardial ischemia/reperfusion injury, cardiac fibrosis, gene transcription or signaling regulation.
Collapse
|
10
|
A Cellular Assay for the Identification and Characterization of Connexin Gap Junction Modulators. Int J Mol Sci 2021; 22:ijms22031417. [PMID: 33572565 PMCID: PMC7866863 DOI: 10.3390/ijms22031417] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 12/18/2022] Open
Abstract
Connexin gap junctions (Cx GJs) enable the passage of small molecules and ions between cells and are therefore important for cell-to-cell communication. Their dysfunction is associated with diseases, and small molecules acting as modulators of GJs may therefore be useful as therapeutic drugs. To identify GJ modulators, suitable assays are needed that allow compound screening. In the present study, we established a novel assay utilizing HeLa cells recombinantly expressing Cx43. Donor cells additionally expressing the Gs protein-coupled adenosine A2A receptor, and biosensor cells expressing a cAMP-sensitive GloSensor luciferase were established. Adenosine A2A receptor activation in the donor cells using a selective agonist results in intracellular cAMP production. The negatively charged cAMP migrates via the Cx43 gap junctions to the biosensor cells and can there be measured by the cAMP-dependent luminescence signal. Cx43 GJ modulators can be expected to impact the transfer of cAMP from the donor to the biosensor cells, since cAMP transit is only possible via GJs. The new assay was validated by testing the standard GJ inhibitor carbenoxolon, which showed a concentration-dependent inhibition of the signal and an IC50 value that was consistent with previously reported values. The assay was demonstrated to be suitable for high-throughput screening.
Collapse
|
11
|
Zheng L, Chenavas S, Kieken F, Trease A, Brownell S, Anbanandam A, Sorgen PL, Spagnol G. Calmodulin Directly Interacts with the Cx43 Carboxyl-Terminus and Cytoplasmic Loop Containing Three ODDD-Linked Mutants (M147T, R148Q, and T154A) that Retain α-Helical Structure, but Exhibit Loss-of-Function and Cellular Trafficking Defects. Biomolecules 2020; 10:biom10101452. [PMID: 33080786 PMCID: PMC7602980 DOI: 10.3390/biom10101452] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/13/2020] [Accepted: 10/14/2020] [Indexed: 12/14/2022] Open
Abstract
The autosomal-dominant pleiotropic disorder called oculodentodigital dysplasia (ODDD) is caused by mutations in the gap junction protein Cx43. Of the 73 mutations identified to date, over one-third are localized in the cytoplasmic loop (Cx43CL) domain. Here, we determined the mechanism by which three ODDD mutations (M147T, R148Q, and T154A), all of which localize within the predicted 1-5-10 calmodulin-binding motif of the Cx43CL, manifest the disease. Nuclear magnetic resonance (NMR) and circular dichroism revealed that the three ODDD mutations had little-to-no effect on the ability of the Cx43CL to form α-helical structure as well as bind calmodulin. Combination of microscopy and a dye-transfer assay uncovered these mutations increased the intracellular level of Cx43 and those that trafficked to the plasma membrane did not form functional channels. NMR also identify that CaM can directly interact with the Cx43CT domain. The Cx43CT residues involved in the CaM interaction overlap with tyrosines phosphorylated by Pyk2 and Src. In vitro and in cyto data provide evidence that the importance of the CaM interaction with the Cx43CT may lie in restricting Pyk2 and Src phosphorylation, and their subsequent downstream effects.
Collapse
Affiliation(s)
- Li Zheng
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA; (L.Z.); (S.C.); (F.K.); (A.T.); (S.B.)
| | - Sylvie Chenavas
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA; (L.Z.); (S.C.); (F.K.); (A.T.); (S.B.)
| | - Fabien Kieken
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA; (L.Z.); (S.C.); (F.K.); (A.T.); (S.B.)
| | - Andrew Trease
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA; (L.Z.); (S.C.); (F.K.); (A.T.); (S.B.)
| | - Sarah Brownell
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA; (L.Z.); (S.C.); (F.K.); (A.T.); (S.B.)
| | - Asokan Anbanandam
- Biomolecular NMR Core Facility, University of Kansas, Lawrence, KS 66045, USA;
| | - Paul L. Sorgen
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA; (L.Z.); (S.C.); (F.K.); (A.T.); (S.B.)
- Correspondence: (P.L.S.); (G.S.)
| | - Gaelle Spagnol
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA; (L.Z.); (S.C.); (F.K.); (A.T.); (S.B.)
- Correspondence: (P.L.S.); (G.S.)
| |
Collapse
|
12
|
Tunneling Nanotubes: The Fuel of Tumor Progression? Trends Cancer 2020; 6:874-888. [DOI: 10.1016/j.trecan.2020.04.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 04/29/2020] [Accepted: 04/30/2020] [Indexed: 12/26/2022]
|
13
|
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.
Collapse
|
14
|
Aseervatham J, Li X, Mitchell CK, Lin YP, Heidelberger R, O’Brien J. Calmodulin Binding to Connexin 35: Specializations to Function as an Electrical Synapse. Int J Mol Sci 2020; 21:E6346. [PMID: 32882943 PMCID: PMC7504508 DOI: 10.3390/ijms21176346] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 08/27/2020] [Accepted: 08/30/2020] [Indexed: 12/25/2022] Open
Abstract
Calmodulin binding is a nearly universal property of gap junction proteins, imparting a calcium-dependent uncoupling behavior that can serve in an emergency to decouple a stressed cell from its neighbors. However, gap junctions that function as electrical synapses within networks of neurons routinely encounter large fluctuations in local cytoplasmic calcium concentration; frequent uncoupling would be impractical and counterproductive. We have studied the properties and functional consequences of calmodulin binding to the electrical synapse protein Connexin 35 (Cx35 or gjd2b), homologous to mammalian Connexin 36 (Cx36 or gjd2). We find that specializations in Cx35 calmodulin binding sites make it relatively impervious to moderately high levels of cytoplasmic calcium. Calmodulin binding to a site in the C-terminus causes uncoupling when calcium reaches low micromolar concentrations, a behavior prevented by mutations that eliminate calmodulin binding. However, milder stimuli promote calcium/calmodulin-dependent protein kinase II activity that potentiates coupling without interference from calmodulin binding. A second calmodulin binding site in the end of the Cx35 cytoplasmic loop, homologous to a calmodulin binding site present in many connexins, binds calmodulin with very low affinity and stoichiometry. Together, the calmodulin binding sites cause Cx35 to uncouple only at extreme levels of intracellular calcium.
Collapse
Affiliation(s)
- Jaya Aseervatham
- Ruiz Department of Ophthalmology & Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; (J.A.); (X.L.); (C.K.M.); (Y.-P.L.)
| | - Xiaofan Li
- Ruiz Department of Ophthalmology & Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; (J.A.); (X.L.); (C.K.M.); (Y.-P.L.)
| | - Cheryl K. Mitchell
- Ruiz Department of Ophthalmology & Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; (J.A.); (X.L.); (C.K.M.); (Y.-P.L.)
| | - Ya-Ping Lin
- Ruiz Department of Ophthalmology & Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; (J.A.); (X.L.); (C.K.M.); (Y.-P.L.)
| | - Ruth Heidelberger
- Department of Neurobiology & Anatomy, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA;
- The MD Anderson Cancer Center/UTHealth Graduate School of Biomedical Sciences, Houston, TX 77030, USA
| | - John O’Brien
- Ruiz Department of Ophthalmology & Visual Science, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; (J.A.); (X.L.); (C.K.M.); (Y.-P.L.)
- The MD Anderson Cancer Center/UTHealth Graduate School of Biomedical Sciences, Houston, TX 77030, USA
| |
Collapse
|
15
|
Abstract
Of the 21 members of the connexin family, 4 (Cx37, Cx40, Cx43, and Cx45) are expressed in the endothelium and/or smooth muscle of intact blood vessels to a variable and dynamically regulated degree. Full-length connexins oligomerize and form channel structures connecting the cytosol of adjacent cells (gap junctions) or the cytosol with the extracellular space (hemichannels). The different connexins vary mainly with regard to length and sequence of their cytosolic COOH-terminal tails. These COOH-terminal parts, which in the case of Cx43 are also translated as independent short isoforms, are involved in various cellular signaling cascades and regulate cell functions. This review focuses on channel-dependent and -independent effects of connexins in vascular cells. Channels play an essential role in coordinating and synchronizing endothelial and smooth muscle activity and in their interplay, in the control of vasomotor actions of blood vessels including endothelial cell reactivity to agonist stimulation, nitric oxide-dependent dilation, and endothelial-derived hyperpolarizing factor-type responses. Further channel-dependent and -independent roles of connexins in blood vessel function range from basic processes of vascular remodeling and angiogenesis to vascular permeability and interactions with leukocytes with the vessel wall. Together, these connexin functions constitute an often underestimated basis for the enormous plasticity of vascular morphology and function enabling the required dynamic adaptation of the vascular system to varying tissue demands.
Collapse
Affiliation(s)
- Ulrich Pohl
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Planegg-Martinsried, Germany; Biomedical Centre, Cardiovascular Physiology, LMU Munich, Planegg-Martinsried, Germany; German Centre for Cardiovascular Research, Partner Site Munich Heart Alliance, Munich, Germany; and Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| |
Collapse
|
16
|
Valiunas V, White TW. Connexin43 and connexin50 channels exhibit different permeability to the second messenger inositol triphosphate. Sci Rep 2020; 10:8744. [PMID: 32457413 PMCID: PMC7251084 DOI: 10.1038/s41598-020-65761-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 05/07/2020] [Indexed: 11/12/2022] Open
Abstract
Gap junction channels made of different connexins have distinct permeability to second messengers, which could affect many cell processes, including lens epithelial cell division. Here, we have compared the permeability of IP3 and Ca2+ through channels made from two connexins, Cx43 and Cx50, that are highly expressed in vertebrate lens epithelial cells. Solute transfer was measured while simultaneously monitoring junctional conductance via dual whole-cell/perforated patch clamp. HeLa cells expressing Cx43 or Cx50 were loaded with Fluo-8, and IP3 or Ca2+ were delivered via patch pipette to one cell of a pair, or to a monolayer while fluorescence intensity changes were recorded. Cx43 channels were permeable to IP3 and Ca2+. Conversely, Cx50 channels were impermeable to IP3, while exhibiting high permeation of Ca2+. Reduced Cx50 permeability to IP3 could play a role in regulating cell division and homeostasis in the lens.
Collapse
Affiliation(s)
- Virginijus Valiunas
- The Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, NY, 11794, USA
| | - Thomas W White
- The Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, NY, 11794, USA.
| |
Collapse
|
17
|
Giaume C, Naus CC, Sáez JC, Leybaert L. Glial Connexins and Pannexins in the Healthy and Diseased Brain. Physiol Rev 2020; 101:93-145. [PMID: 32326824 DOI: 10.1152/physrev.00043.2018] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Over the past several decades a large amount of data have established that glial cells, the main cell population in the brain, dynamically interact with neurons and thus impact their activity and survival. One typical feature of glia is their marked expression of several connexins, the membrane proteins forming intercellular gap junction channels and hemichannels. Pannexins, which have a tetraspan membrane topology as connexins, are also detected in glial cells. Here, we review the evidence that connexin and pannexin channels are actively involved in dynamic and metabolic neuroglial interactions in physiological as well as in pathological situations. These features of neuroglial interactions open the way to identify novel non-neuronal aspects that allow for a better understanding of behavior and information processing performed by neurons. This will also complement the "neurocentric" view by facilitating the development of glia-targeted therapeutic strategies in brain disease.
Collapse
Affiliation(s)
- Christian Giaume
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, Paris, France; University Pierre et Marie Curie, Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France; Department of Cellular & Physiological Sciences, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile; Instituo de Neurociencias, Centro Interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso, Chile; Physiology Group, Department of Basic and Applied Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Christian C Naus
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, Paris, France; University Pierre et Marie Curie, Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France; Department of Cellular & Physiological Sciences, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile; Instituo de Neurociencias, Centro Interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso, Chile; Physiology Group, Department of Basic and Applied Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Juan C Sáez
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, Paris, France; University Pierre et Marie Curie, Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France; Department of Cellular & Physiological Sciences, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile; Instituo de Neurociencias, Centro Interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso, Chile; Physiology Group, Department of Basic and Applied Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Luc Leybaert
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, Paris, France; University Pierre et Marie Curie, Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France; Department of Cellular & Physiological Sciences, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile; Instituo de Neurociencias, Centro Interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso, Chile; Physiology Group, Department of Basic and Applied Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| |
Collapse
|
18
|
Kim HJ, Kim MJ, Mostafa MN, Park JH, Choi HS, Kim YS, Choi EK. RhoA/ROCK Regulates Prion Pathogenesis by Controlling Connexin 43 Activity. Int J Mol Sci 2020; 21:ijms21041255. [PMID: 32070020 PMCID: PMC7072953 DOI: 10.3390/ijms21041255] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 02/10/2020] [Accepted: 02/11/2020] [Indexed: 11/16/2022] Open
Abstract
Scrapie infection, which converts cellular prion protein (PrPC) into the pathological and infectious isoform (PrPSc), leads to neuronal cell death, glial cell activation and PrPSc accumulation. Previous studies reported that PrPC regulates RhoA/Rho-associated kinase (ROCK) signaling and that connexin 43 (Cx43) expression is upregulated in in vitro and in vivo prion-infected models. However, whether there is a link between RhoA/ROCK and Cx43 in prion disease pathogenesis is uncertain. Here, we investigated the role of RhoA/ROCK signaling and Cx43 in prion diseases using in vitro and in vivo models. Scrapie infection induced RhoA activation, accompanied by increased phosphorylation of LIM kinase 1/2 (LIMK1/2) at Thr508/Thr505 and cofilin at Ser3 and reduced phosphorylation of RhoA at Ser188 in hippocampal neuronal cells and brains of mice. Scrapie infection-induced RhoA activation also resulted in PrPSc accumulation followed by a reduction in the interaction between RhoA and p190RhoGAP (a GTPase-activating protein). Interestingly, scrapie infection significantly enhanced the interaction between RhoA and Cx43. Moreover, RhoA and Cx43 colocalization was more visible in both the membrane and cytoplasm of scrapie-infected hippocampal neuronal cells than in controls. Finally, RhoA and ROCK inhibition reduced PrPSc accumulation and the RhoA/Cx43 interaction, leading to decreased Cx43 hemichannel activity in scrapie-infected hippocampal neuronal cells. These findings suggest that RhoA/ROCK regulates Cx43 activity, which may have an important role in the pathogenesis of prion disease.
Collapse
Affiliation(s)
- Hee-Jun Kim
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do 14066, Korea; (H.-J.K.); (M.-J.K.); (M.N.M.); (J.-H.P.); (H.-S.C.); (Y.-S.K.)
| | - Mo-Jong Kim
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do 14066, Korea; (H.-J.K.); (M.-J.K.); (M.N.M.); (J.-H.P.); (H.-S.C.); (Y.-S.K.)
- Department of Biomedical Gerontology, Graduate School of Hallym University, Chuncheon, Gangwon-do 24252, Korea
| | - Mohd Najib Mostafa
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do 14066, Korea; (H.-J.K.); (M.-J.K.); (M.N.M.); (J.-H.P.); (H.-S.C.); (Y.-S.K.)
- Department of Biomedical Gerontology, Graduate School of Hallym University, Chuncheon, Gangwon-do 24252, Korea
| | - Jeong-Ho Park
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do 14066, Korea; (H.-J.K.); (M.-J.K.); (M.N.M.); (J.-H.P.); (H.-S.C.); (Y.-S.K.)
| | - Hong-Seok Choi
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do 14066, Korea; (H.-J.K.); (M.-J.K.); (M.N.M.); (J.-H.P.); (H.-S.C.); (Y.-S.K.)
| | - Yong-Sun Kim
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do 14066, Korea; (H.-J.K.); (M.-J.K.); (M.N.M.); (J.-H.P.); (H.-S.C.); (Y.-S.K.)
- Department of Microbiology, College of Medicine, Hallym University, Chuncheon, Gangwon-do 24252, Korea
| | - Eun-Kyoung Choi
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do 14066, Korea; (H.-J.K.); (M.-J.K.); (M.N.M.); (J.-H.P.); (H.-S.C.); (Y.-S.K.)
- Department of Biomedical Gerontology, Graduate School of Hallym University, Chuncheon, Gangwon-do 24252, Korea
- Correspondence: ; Tel.: +82-31-380-1893; Fax: +82-31-388-3427
| |
Collapse
|
19
|
Peracchia C. Calmodulin-Mediated Regulation of Gap Junction Channels. Int J Mol Sci 2020; 21:E485. [PMID: 31940951 PMCID: PMC7014422 DOI: 10.3390/ijms21020485] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/03/2020] [Accepted: 01/06/2020] [Indexed: 12/25/2022] Open
Abstract
Evidence that neighboring cells uncouple from each other as one dies surfaced in the late 19th century, but it took almost a century for scientists to start understanding the uncoupling mechanism (chemical gating). The role of cytosolic free calcium (Ca2+i) in cell-cell channel gating was first reported in the mid-sixties. In these studies, only micromolar [Ca2+]i were believed to affect gating-concentrations reachable only in cell death, which would discard Ca2+i as a fine modulator of cell coupling. More recently, however, numerous researchers, including us, have reported the effectiveness of nanomolar [Ca2+]i. Since connexins do not have high-affinity calcium sites, the effectiveness of nanomolar [Ca2+]i suggests the role of Ca-modulated proteins, with calmodulin (CaM) being most obvious. Indeed, in 1981 we first reported that a CaM-inhibitor prevents chemical gating. Since then, the CaM role in gating has been confirmed by studies that tested it with a variety of approaches such as treatments with CaM-inhibitors, inhibition of CaM expression, expression of CaM mutants, immunofluorescent co-localization of CaM and gap junctions, and binding of CaM to peptides mimicking connexin domains identified as CaM targets. Our gating model envisions Ca2+-CaM to directly gate the channels by acting as a plug ("Cork" gating model), and probably also by affecting connexin conformation.
Collapse
Affiliation(s)
- Camillo Peracchia
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| |
Collapse
|
20
|
Inner Ear Connexin Channels: Roles in Development and Maintenance of Cochlear Function. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a033233. [PMID: 30181354 DOI: 10.1101/cshperspect.a033233] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Connexin 26 and connexin 30 are the prevailing isoforms in the epithelial and connective tissue gap junction systems of the developing and mature cochlea. The most frequently encountered variants of the genes that encode these connexins, which are transcriptionally coregulated, determine complete loss of protein function and are the predominant cause of prelingual hereditary deafness. Reducing connexin 26 expression by Cre/loxP recombination in the inner ear of adult mice results in a decreased endocochlear potential, increased hearing thresholds, and loss of >90% of outer hair cells, indicating that this connexin is essential for maintenance of cochlear function. In the developing cochlea, connexins are necessary for intercellular calcium signaling activity. Ribbon synapses and basolateral membrane currents fail to mature in inner hair cells of mice that are born with reduced connexin expression, even though hair cells do not express any connexin. In contrast, pannexin 1, an alternative mediator of intercellular signaling, is dispensable for hearing acquisition and auditory function.
Collapse
|
21
|
Mayorquin LC, Rodriguez AV, Sutachan JJ, Albarracín SL. Connexin-Mediated Functional and Metabolic Coupling Between Astrocytes and Neurons. Front Mol Neurosci 2018; 11:118. [PMID: 29695954 PMCID: PMC5905222 DOI: 10.3389/fnmol.2018.00118] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 03/27/2018] [Indexed: 01/24/2023] Open
Abstract
The central nervous system (CNS) requires sophisticated regulation of neuronal activity. This modulation is partly accomplished by non-neuronal cells, characterized by the presence of transmembrane gap junctions (GJs) and hemichannels (HCs). This allows small molecule diffusion to guarantee neuronal synaptic activity and plasticity. Astrocytes are metabolically and functionally coupled to neurons by the uptake, binding and recycling of neurotransmitters. In addition, astrocytes release metabolites, such as glutamate, glutamine, D-serine, adenosine triphosphate (ATP) and lactate, regulating synaptic activity and plasticity by pre- and postsynaptic mechanisms. Uncoupling neuroglial communication leads to alterations in synaptic transmission that can be detrimental to neuronal circuit function and behavior. Therefore, understanding the pathways and mechanisms involved in this intercellular communication is fundamental for the search of new targets that can be used for several neurological disease treatments. This review will focus on molecular mechanisms mediating physiological and pathological coupling between astrocytes and neurons through GJs and HCs.
Collapse
Affiliation(s)
- Lady C Mayorquin
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Andrea V Rodriguez
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Jhon-Jairo Sutachan
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Sonia L Albarracín
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
| |
Collapse
|
22
|
Ji X, Chou X, Ge Z, Ding F, Gao H, Wu Q. Benzo[a
]pyrene-decreased gap junctional intercellular communication via calcium/calmodulin signaling increases apoptosis in TM4 cells. J Appl Toxicol 2018; 38:1091-1103. [DOI: 10.1002/jat.3618] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/07/2018] [Accepted: 02/07/2018] [Indexed: 12/12/2022]
Affiliation(s)
- Xiaoli Ji
- School of Public Health; Fudan University and Key Laboratory of Public Health Safety, Ministry of Education; 130 Dong An Road Shanghai 200032 China
| | - Xin Chou
- School of Public Health; Fudan University and Key Laboratory of Public Health Safety, Ministry of Education; 130 Dong An Road Shanghai 200032 China
| | - Zehe Ge
- School of Public Health; Fudan University and Key Laboratory of Public Health Safety, Ministry of Education; 130 Dong An Road Shanghai 200032 China
| | - Fan Ding
- School of Public Health; Fudan University and Key Laboratory of Public Health Safety, Ministry of Education; 130 Dong An Road Shanghai 200032 China
| | - Hui Gao
- School of Public Health; Fudan University and Key Laboratory of Public Health Safety, Ministry of Education; 130 Dong An Road Shanghai 200032 China
| | - Qing Wu
- School of Public Health; Fudan University and Key Laboratory of Public Health Safety, Ministry of Education; 130 Dong An Road Shanghai 200032 China
| |
Collapse
|
23
|
Garciarena CD, Malik A, Swietach P, Moreno AP, Vaughan-Jones RD. Distinct moieties underlie biphasic H + gating of connexin43 channels, producing a pH optimum for intercellular communication. FASEB J 2018; 32:1969-1981. [PMID: 29183963 PMCID: PMC5893178 DOI: 10.1096/fj.201700876r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Most mammalian cells can intercommunicate via connexin-assembled, gap-junctional channels. To regulate signal transmission, connexin (Cx) channel permeability must respond dynamically to physiological and pathophysiological stimuli. One key stimulus is intracellular pH (pHi), which is modulated by a tissue’s metabolic and perfusion status. Our understanding of the molecular mechanism of H+ gating of Cx43 channels—the major isoform in the heart and brain—is incomplete. To interrogate the effects of acidic and alkaline pHi on Cx43 channels, we combined voltage-clamp electrophysiology with pHi imaging and photolytic H+ uncaging, performed over a range of pHi values. We demonstrate that Cx43 channels expressed in HeLa or N2a cell pairs are gated biphasically by pHivia a process that consists of activation by H+ ions at alkaline pHi and inhibition at more acidic pHi. For Cx43 channel–mediated solute/ion transmission, the ensemble of these effects produces a pHi optimum, near resting pHi. By using Cx43 mutants, we demonstrate that alkaline gating involves cysteine residues of the C terminus and is independent of motifs previously implicated in acidic gating. Thus, we present a molecular mechanism by which cytoplasmic acid–base chemistry fine tunes intercellular communication and establishes conditions for the optimal transmission of solutes and signals in tissues, such as the heart and brain.—Garciarena, C. D., Malik, A., Swietach, P., Moreno, A. P., Vaughan-Jones, R. D. Distinct moieties underlie biphasic H+ gating of connexin43 channels, producing a pH optimum for intercellular communication.
Collapse
Affiliation(s)
- Carolina D Garciarena
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Oxford, United Kingdom.,Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Akif Malik
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Oxford, United Kingdom
| | - Pawel Swietach
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Oxford, United Kingdom
| | - Alonso P Moreno
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA
| | - Richard D Vaughan-Jones
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
24
|
Grubišić V, Verkhratsky A, Zorec R, Parpura V. Enteric glia regulate gut motility in health and disease. Brain Res Bull 2018; 136:109-117. [PMID: 28363846 PMCID: PMC5620110 DOI: 10.1016/j.brainresbull.2017.03.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 02/20/2017] [Accepted: 03/28/2017] [Indexed: 12/16/2022]
Abstract
The enteric nervous system, often referred to as the second brain, is the largest assembly of neurons and glia outside the central nervous system. The enteric nervous system resides within the wall of the digestive tract and regulates local gut reflexes involved in gastrointestinal motility and fluid transport; these functions can be accomplished in the absence of the extrinsic innervation from the central nervous system. It is neurons and their circuitry within the enteric nervous system that govern the gut reflexes. However, it is becoming clear that enteric glial cells are also actively involved in this process through the bidirectional signaling with neurons and other cells in the gut wall. We synthesize the recently discovered modulatory roles of enteric gliotransmission in gut motility and provide our perspective for future lines of research.
Collapse
Affiliation(s)
- Vladimir Grubišić
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA; Neuroscience Program, Department of Physiology, Michigan State University, 567 Wilson Road, East Lansing, MI, 48824, USA
| | - Alexei Verkhratsky
- The University of Manchester, Manchester, UK; Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology University of Ljubljana, Ljubljana, Slovenia; Celica BIOMEDICAL, Ljubljana, Slovenia
| | - Vladimir Parpura
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA.
| |
Collapse
|
25
|
Wei Y, Meng T, Sun C. Protective effect of diltiazem on myocardial ischemic rats induced by isoproterenol. Mol Med Rep 2017; 17:495-501. [PMID: 29115512 DOI: 10.3892/mmr.2017.7906] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 08/31/2017] [Indexed: 11/06/2022] Open
Abstract
The aim of the present study was to analyze the effect of diltiazem on myocardial fibrosis and remodeling of connexin43 (Cx43) in myocardial ischemic rats and mechanisms underlying these processes. A total of 36 Sprague‑Dawley rats were randomly allocated into three groups (control, isoproterenol and isoproterenol with diltiazem). The myocardial ischemic model was established by 5 mg/kg/day isoproterenol administration for 7 days, and the diltiazem group received 25 mg/kg/day diltiazem for 4 weeks. Following the treatment, paraffin sections were prepared to observe microstructural changes and to evaluate the concentration of Ca2+ in myocardium. The expression of transforming growth factors‑β1 (TGF‑β1), mothers against decapentaplegic homologues (Smad)2 and 7 and Cx43, were analyzed by reverse transcription-quantitative polymerase chain reaction and western blotting. The percentage Cx43 expression in intercalated disks was evaluated using immunohistochemistry. Fibrosis did not differ significantly between the control and the diltiazem‑treated group. The concentration of Ca2+ increased in the myocardium of model rats. The expression of Smad7 and Cx43 was decreased in the rat model, while the expression of TGF‑β1 and Smad2 was increased. There was a significant decrease in the relative abundance of intercalated disk Cx43 in the model group. The results of the present study suggest that diltiazem may serve a protective role during remodeling of myocardial ischemia, especially in fibrosis and Cx43 remodeling.
Collapse
Affiliation(s)
- Yuejiao Wei
- Department of Cardiovascular Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Tianyu Meng
- Department of Cardiovascular Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Chaofeng Sun
- Department of Cardiovascular Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| |
Collapse
|
26
|
Leybaert L, Lampe PD, Dhein S, Kwak BR, Ferdinandy P, Beyer EC, Laird DW, Naus CC, Green CR, Schulz R. Connexins in Cardiovascular and Neurovascular Health and Disease: Pharmacological Implications. Pharmacol Rev 2017; 69:396-478. [PMID: 28931622 PMCID: PMC5612248 DOI: 10.1124/pr.115.012062] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Connexins are ubiquitous channel forming proteins that assemble as plasma membrane hemichannels and as intercellular gap junction channels that directly connect cells. In the heart, gap junction channels electrically connect myocytes and specialized conductive tissues to coordinate the atrial and ventricular contraction/relaxation cycles and pump function. In blood vessels, these channels facilitate long-distance endothelial cell communication, synchronize smooth muscle cell contraction, and support endothelial-smooth muscle cell communication. In the central nervous system they form cellular syncytia and coordinate neural function. Gap junction channels are normally open and hemichannels are normally closed, but pathologic conditions may restrict gap junction communication and promote hemichannel opening, thereby disturbing a delicate cellular communication balance. Until recently, most connexin-targeting agents exhibited little specificity and several off-target effects. Recent work with peptide-based approaches has demonstrated improved specificity and opened avenues for a more rational approach toward independently modulating the function of gap junctions and hemichannels. We here review the role of connexins and their channels in cardiovascular and neurovascular health and disease, focusing on crucial regulatory aspects and identification of potential targets to modify their function. We conclude that peptide-based investigations have raised several new opportunities for interfering with connexins and their channels that may soon allow preservation of gap junction communication, inhibition of hemichannel opening, and mitigation of inflammatory signaling.
Collapse
Affiliation(s)
- Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Paul D Lampe
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Stefan Dhein
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Brenda R Kwak
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Peter Ferdinandy
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Eric C Beyer
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Dale W Laird
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Christian C Naus
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Colin R Green
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Rainer Schulz
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| |
Collapse
|
27
|
HIV-1 Tat-induced diarrhea evokes an enteric glia-dependent neuroinflammatory response in the central nervous system. Sci Rep 2017; 7:7735. [PMID: 28798420 PMCID: PMC5552820 DOI: 10.1038/s41598-017-05245-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 05/25/2017] [Indexed: 02/07/2023] Open
Abstract
Despite the effectiveness of combined anti-retroviral therapy, human immunodeficiency virus (HIV) infected-patients frequently report diarrhea and neuropsychological deficits. It is claimed that the viral HIV-1 Trans activating factor (HIV-1 Tat) protein is responsible for both diarrhea and neurotoxic effects, but the underlying mechanisms are not known. We hypothesize that colonic application of HIV-1 Tat activates glial cells of the enteric nervous system (EGCs), leading to a neuroinflammatory response able to propagate to the central nervous system. We demonstrated that HIV-1 Tat-induced diarrhea was associated with a significant activation of glial cells within the colonic wall, the spinal cord and the frontal cortex, and caused a consistent impairment of the cognitive performances. The inhibition of glial cells activity by lidocaine, completely abolished the above-described effects. These observations point out the role of glial cells as putative effectors in HIV-1 Tat-associated gastrointestinal and neurological manifestations and key regulators of gut-brain signaling.
Collapse
|
28
|
Yoon JK, Lee TI, Bhang SH, Shin JY, Myoung JM, Kim BS. Stretchable Piezoelectric Substrate Providing Pulsatile Mechanoelectric Cues for Cardiomyogenic Differentiation of Mesenchymal Stem Cells. ACS APPLIED MATERIALS & INTERFACES 2017; 9:22101-22111. [PMID: 28560866 DOI: 10.1021/acsami.7b03050] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ex vivo induction of cardiomyogenic differentiation of mesenchymal stem cells (MSCs) before implantation would potentiate therapeutic efficacy of stem cell therapies for ischemic heart diseases because MSCs rarely undergo cardiomyogenic differentiation following implantation. In cardiac microenvironments, electric pulse and cyclic mechanical strain are sequentially produced. However, no study has applied the pulsatile mechanoelectric cues (PMEC) to stimulate cardiomyogenic differentiation of MSCs ex vivo. In this study, we developed a stretchable piezoelectric substrate (SPS) that can provide PMEC to human MSCs (hMSCs) for cardiomyogenic differentiation ex vivo. Our data showed that hMSCs subjected to PMEC by SPS underwent promoted cardiac phenotype development: cell alignment and the expression of cardiac markers (i.e., cardiac transcription factors, structural proteins, ion channel proteins, and gap junction proteins). The enhanced cardiac phenotype development was mediated by the upregulation of cardiomyogenic differentiation-related autocrine factor expression, focal adhesion kinase, and extracellular signal-regulated kinases signaling pathways. Thus, SPS providing electrical and mechanical regulation of stem cells may be utilized to potentiate hMSC therapies for myocardial infarction and provide a tool for the study of stem cell biology.
Collapse
Affiliation(s)
| | - Tae Il Lee
- Department of BioNano Technology, Gachon University , Seongnam 13557, Republic of Korea
| | - Suk Ho Bhang
- School of Chemical Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | | | - Jae-Min Myoung
- Department of Materials Science and Engineering, Yonsei University , Seoul 03722, Republic of Korea
| | | |
Collapse
|
29
|
Lee GH, Jang B, Choi HS, Kim HJ, Park JH, Jeon YC, Carp RI, Kim YS, Choi EK. Upregulation of Connexin 43 Expression Via C-Jun N-Terminal Kinase Signaling in Prion Disease. J Alzheimers Dis 2016; 49:1005-19. [PMID: 26599051 DOI: 10.3233/jad-150283] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Prion infection leads to neuronal cell death, glial cell activation, and the accumulation of misfolded prion proteins. However, the altered cellular environments in animals with prion diseases are poorly understood. In the central nervous system, cells connect the cytoplasm of adjacent cells via connexin (Cx)-assembled gap junction channels to allow the direct exchange of small molecules, including ions, neurotransmitters, and signaling molecules, which regulate the activities of the connected cells. Here, we investigate the role of Cx43 in the pathogenesis of prion diseases. Upregulated Cx43 expression, which was dependent on c-Jun N-Terminal Kinase (JNK)/c-Jun signaling cascades, was found in prion-affected brain tissues and hippocampal neuronal cells. Scrapie infection-induced Cx43 formed aggregated plaques within the cytoplasmic compartments at the cell-cell interfaces. The ethidium bromide (EtBr) uptake assay and scrape-loading dye transfer assay demonstrated that increased Cx43 has functional consequences for the activity of Cx43 hemichannels. Interestingly, blockade of PrPSc accumulation reduced Cx43 expression through the inhibition of JNK signaling, indicating that PrPSc accumulation may be directly involved in JNK activation-mediated Cx43 upregulation. Overall, our findings describe a scrapie infection-mediated novel regulatory signaling pathway of Cx43 expression and may suggest a role for Cx43 in the pathogenesis of prion diseases.
Collapse
Affiliation(s)
- Geon-Hwi Lee
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Republic of Korea.,Department of Biomedical Gerontology, Graduate School of Hallym University, Chuncheon, Gangwon-do, Republic of Korea
| | - Byungki Jang
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Republic of Korea
| | - Hong-Seok Choi
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Republic of Korea.,Department of Microbiology, College of Medicine, Hallym University, Chuncheon, Gangwon-do, Republic of Korea
| | - Hee-Jun Kim
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Republic of Korea
| | - Jeong-Ho Park
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Republic of Korea.,Department of Microbiology, College of Medicine, Hallym University, Chuncheon, Gangwon-do, Republic of Korea
| | - Yong-Chul Jeon
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Republic of Korea
| | - Richard I Carp
- New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Yong-Sun Kim
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Republic of Korea.,Department of Microbiology, College of Medicine, Hallym University, Chuncheon, Gangwon-do, Republic of Korea
| | - Eun-Kyoung Choi
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Republic of Korea.,Department of Biomedical Gerontology, Graduate School of Hallym University, Chuncheon, Gangwon-do, Republic of Korea
| |
Collapse
|
30
|
Diezmos EF, Bertrand PP, Liu L. Purinergic Signaling in Gut Inflammation: The Role of Connexins and Pannexins. Front Neurosci 2016; 10:311. [PMID: 27445679 PMCID: PMC4925662 DOI: 10.3389/fnins.2016.00311] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 06/20/2016] [Indexed: 12/13/2022] Open
Abstract
Purinergic receptors play an important role in inflammation, and can be activated by ATP released via pannexin channels and/or connexin hemichannels. The purinergic P2X7 receptor (P2X7R) is of interest since it is involved in apoptosis when activated. Most studies focus on the influence of pannexin-1 (Panx1) and connexin 43 (Cx43) on ATP release and how it affects P2X7R function during inflammation. Inflammatory bowel disease (IBD) is characterized by uncontrolled inflammation within the gastrointestinal system. At present, the pathophysiology of this disease remains largely unknown but it may involve the interplay between P2X7R, Panx1, and Cx43. There are two main types of IBD, ulcerative colitis and Crohn's disease, that are classified by their location and frequency of inflammation. Current research suggests that alterations to normal functioning of innate and adaptive immunity may be a factor in disease progression. The involvement of purinergic receptors, connexins, and pannexins in IBD is a relatively novel notion in the context of gastrointestinal inflammation, and has been explored by various research groups. Thus, the present review focuses on the current research involving connexins, pannexins, and purinergic receptors within the gut and enteric nervous system, and will examine their involvement in inflammation and the pathophysiology of IBD.
Collapse
Affiliation(s)
- Erica F Diezmos
- School of Medical Sciences, University of New South Wales Sydney, NSW, Australia
| | - Paul P Bertrand
- School of Medical Sciences, University of New South WalesSydney, NSW, Australia; School of Medical Sciences, RMIT UniversityBundoora, VIC, Australia
| | - Lu Liu
- School of Medical Sciences, University of New South Wales Sydney, NSW, Australia
| |
Collapse
|
31
|
Cell communication across gap junctions: a historical perspective and current developments. Biochem Soc Trans 2016; 43:450-9. [PMID: 26009190 DOI: 10.1042/bst20150056] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Collaborative communication lies at the centre of multicellular life. Gap junctions (GJs) are surface membrane structures that allow direct communication between cells. They were discovered in the 1960s following the convergence of the detection of low-resistance electrical interactions between cells and anatomical studies of intercellular contact points. GJs purified from liver plasma membranes contained a 27 kDa protein constituent; it was later named Cx32 (connexin 32) after its full sequence was determined by recombinant technology. Identification of Cx43 in heart and later by a further GJ protein, Cx26 followed. Cxs have a tetraspan organization in the membrane and oligomerize during intracellular transit to the plasma membrane; these were shown to be hexameric hemichannels (connexons) that could interact end-to-end to generate GJs at areas of cell-to-cell contact. The structure of the GJ was confirmed and refined by a combination of biochemical and structural approaches. Progress continues towards obtaining higher atomic 3D resolution of the GJ channel. Today, there are 20 and 21 highly conserved members of the Cx family in the human and mouse genomes respectively. Model organisms such as Xenopus oocytes and zebra fish are increasingly used to relate structure to function. Proteins that form similar large pore membrane channels in cells called pannexins have also been identified in chordates. Innexins form GJs in prechordates; these two other proteins, although functionally similar, are very different in amino acid sequence to the Cxs. A time line tracing the historical progression of wide ranging research in GJ biology over 60 years is mapped out. The molecular basis of channel dysfunctions in disease is becoming evident and progress towards addressing Cx channel-dependent pathologies, especially in ischaemia and tissue repair, continues.
Collapse
|
32
|
George SA, Sciuto KJ, Lin J, Salama ME, Keener JP, Gourdie RG, Poelzing S. Extracellular sodium and potassium levels modulate cardiac conduction in mice heterozygous null for the Connexin43 gene. Pflugers Arch 2015; 467:2287-97. [PMID: 25771952 DOI: 10.1007/s00424-015-1698-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 02/18/2015] [Accepted: 03/02/2015] [Indexed: 11/27/2022]
Abstract
UNLABELLED Several studies have disagreed on measurements of cardiac conduction velocity (CV) in mice with a heterozygous knockout of the connexin gene Gja1--a mutation that reduces the gap junction (GJ) protein, Connexin43 (Cx43), by 50 %. We noted that perfusate ionic composition varied between studies and hypothesized that extracellular ionic concentration modulates CV dependence on GJs. CV was measured by optically mapping wild-type (WT) and heterozygous null (HZ) hearts serially perfused with solutions previously associated with no change (Solution 1) or CV slowing (Solution 2). In WT hearts, CV was similar for Solutions 1 and 2. However, consistent with the hypothesis, Solution 2 in HZ hearts slowed transverse CV (CVT) relative to Solution 1. Previously, we showed CV slowing in a manner consistent with ephaptic conduction correlated with increased perinexal inter-membrane width (W P) at GJ edges. Thus, W P was measured following perfusion with systematically adjusted [Na(+)]o and [K(+)]o in Solutions 1 and 2. A wider W P was associated with reduced CVT in WT and HZ hearts, with the greatest effect in HZ hearts. Increasing [Na(+)]o increased CVT only in HZ hearts. Increasing [K(+)]o slowed CVT in both WT and HZ hearts with large W P but only in HZ hearts with narrow W P. CONCLUSION When perinexi are wide, decreasing excitability by modulating [Na(+)]o and [K(+)]o increases CV sensitivity to reduced Cx43. By contrast, CV is less sensitive to Cx43 and ion composition when perinexi are narrow. These results are consistent with cardiac conduction dependence on both GJ and non-GJ (ephaptic) mechanisms.
Collapse
Affiliation(s)
- Sharon A George
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
- Center for Heart and Regenerative Medicine, Virginia Tech Carilion Research Institute, 2 Riverside Circle, Roanoke, VA, 24016, USA
| | - Katherine J Sciuto
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Joyce Lin
- Department of Mathematics, California Polytechnic State University, San Luis Obispo, CA, USA
| | - Mohamed E Salama
- Department of Pathology, University of Utah and ARUP Reference Lab Institute of Research, Salt Lake City, UT, USA
| | - James P Keener
- Department of Mathematics, University of Utah, Salt Lake City, UT, USA
| | - Robert G Gourdie
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
- Center for Heart and Regenerative Medicine, Virginia Tech Carilion Research Institute, 2 Riverside Circle, Roanoke, VA, 24016, USA
| | - Steven Poelzing
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
- Center for Heart and Regenerative Medicine, Virginia Tech Carilion Research Institute, 2 Riverside Circle, Roanoke, VA, 24016, USA.
| |
Collapse
|
33
|
Yang Y, Yeo CK. Conceptual Network Model From Sensory Neurons to Astrocytes of the Human Nervous System. IEEE Trans Biomed Eng 2015; 62:1843-52. [PMID: 25706505 DOI: 10.1109/tbme.2015.2405549] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
From a single-cell animal like paramecium to vertebrates like ape, the nervous system plays an important role in responding to the variations of the environment. Compared to animals, the nervous system in the human body possesses more intricate organization and utility. The nervous system anatomy has been understood progressively, yet the explanation at the cell level regarding complete information transmission is still lacking. Along the signal pathway toward the brain, an external stimulus first activates action potentials in the sensing neuron and these electric pulses transmit along the spinal nerve or cranial nerve to the neurons in the brain. Second, calcium elevation is triggered in the branch of astrocyte at the tripartite synapse. Third, the local calcium wave expands to the entire territory of the astrocyte. Finally, the calcium wave propagates to the neighboring astrocyte via gap junction channel. In our study, we integrate the existing mathematical model and biological experiments in each step of the signal transduction to establish a conceptual network model for the human nervous system. The network is composed of four layers and the communication protocols of each layer could be adapted to entities with different characterizations. We verify our simulation results against the available biological experiments and mathematical models and provide a test case of the integrated network. As the production of conscious episode in the human nervous system is still under intense research, our model serves as a useful tool to facilitate, complement and verify current and future study in human cognition.
Collapse
|
34
|
Rutter GA, Hodson DJ. Beta cell connectivity in pancreatic islets: a type 2 diabetes target? Cell Mol Life Sci 2015; 72:453-467. [PMID: 25323131 PMCID: PMC11113448 DOI: 10.1007/s00018-014-1755-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/30/2014] [Accepted: 10/01/2014] [Indexed: 12/12/2022]
Abstract
Beta cell connectivity describes the phenomenon whereby the islet context improves insulin secretion by providing a three-dimensional platform for intercellular signaling processes. Thus, the precise flow of information through homotypically interconnected beta cells leads to the large-scale organization of hormone release activities, influencing cell responses to glucose and other secretagogues. Although a phenomenon whose importance has arguably been underappreciated in islet biology until recently, a growing number of studies suggest that such cell-cell communication is a fundamental property of this micro-organ. Hence, connectivity may plausibly be targeted by both environmental and genetic factors in type 2 diabetes mellitus (T2DM) to perturb normal beta cell function and insulin release. Here, we review the mechanisms that contribute to beta cell connectivity, discuss how these may fail during T2DM, and examine approaches to restore insulin secretion by boosting cell communication.
Collapse
Affiliation(s)
- Guy A Rutter
- Section of Cell Biology, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
| | - David J Hodson
- Section of Cell Biology, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| |
Collapse
|
35
|
Shaikh Qureshi WM, Latif ML, Parker TL, Pratten MK. Evaluation of Bupropion Hydrochloride Developmental Cardiotoxic Effects in Chick Cardiomyocyte Micromass Culture and stem cell derived Cardiomyocyte Systems. ACTA ACUST UNITED AC 2014; 101:371-8. [DOI: 10.1002/bdrb.21121] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 08/04/2014] [Indexed: 01/23/2023]
Affiliation(s)
- W. M. Shaikh Qureshi
- School of Biomedical Sciences; Queen's Medical Centre; University of Nottingham; Nottinghamshire United Kingdom
| | - Muhammad Liaque Latif
- School of Biomedical Sciences; Queen's Medical Centre; University of Nottingham; Nottinghamshire United Kingdom
| | - Terry L. Parker
- School of Biomedical Sciences; Queen's Medical Centre; University of Nottingham; Nottinghamshire United Kingdom
| | - Margaret K. Pratten
- School of Biomedical Sciences; Queen's Medical Centre; University of Nottingham; Nottinghamshire United Kingdom
| |
Collapse
|
36
|
Billaud M, Lohman AW, Johnstone SR, Biwer LA, Mutchler S, Isakson BE. Regulation of cellular communication by signaling microdomains in the blood vessel wall. Pharmacol Rev 2014; 66:513-69. [PMID: 24671377 DOI: 10.1124/pr.112.007351] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
It has become increasingly clear that the accumulation of proteins in specific regions of the plasma membrane can facilitate cellular communication. These regions, termed signaling microdomains, are found throughout the blood vessel wall where cellular communication, both within and between cell types, must be tightly regulated to maintain proper vascular function. We will define a cellular signaling microdomain and apply this definition to the plethora of means by which cellular communication has been hypothesized to occur in the blood vessel wall. To that end, we make a case for three broad areas of cellular communication where signaling microdomains could play an important role: 1) paracrine release of free radicals and gaseous molecules such as nitric oxide and reactive oxygen species; 2) role of ion channels including gap junctions and potassium channels, especially those associated with the endothelium-derived hyperpolarization mediated signaling, and lastly, 3) mechanism of exocytosis that has considerable oversight by signaling microdomains, especially those associated with the release of von Willebrand factor. When summed, we believe that it is clear that the organization and regulation of signaling microdomains is an essential component to vessel wall function.
Collapse
Affiliation(s)
- Marie Billaud
- Dept. of Molecular Physiology and Biophysics, University of Virginia School of Medicine, PO Box 801394, Charlottesville, VA 22902.
| | | | | | | | | | | |
Collapse
|
37
|
The arrhythmogenic effect of self-assembling nanopeptide hydrogel scaffolds on neonatal mouse cardiomyocytes. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2014; 10:1065-73. [PMID: 24491398 DOI: 10.1016/j.nano.2014.01.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 01/10/2014] [Accepted: 01/22/2014] [Indexed: 01/16/2023]
Abstract
UNLABELLED The chaotic spatial disarray due to extracellular matrix expansion disrupts cardiomyocytes interaction and causes arrhythmia. We hypothesized that disordered nanopeptide scaffolds can mimic the chaotic spatial disarray related to cardiac fibrosis and have arrhythmogenic effects on cardiomyocytes. Primary mouse cardiomyocytes were cultured in 2D traditional and 3D nanopeptide hydrogel scaffold systems. Cardiomyocytes in 3D scaffolds showed irregular spontaneous contractile activity as compared with 2D culture controls. Calcium fluorimetric imaging revealed that basal intracellular calcium level increased 1.42-fold in cardiomyocytes cultured in the 3D scaffold, in vitro. The mRNA levels of sarcoplasmic reticulum calcium transport ATPase, ryanodine 2 receptor and connexin 43 elevated 2.14-fold, 2.33-fold and 2.62-fold in 3D compared with 2D. Immunofluorescence imaging revealed lateralization of the distribution of connexin 43 in 3D group. These findings suggest that 3D hydrogel culture system provides a model for the development of cardiac dysrhythmia. These limitations should be considered during cardiac tissue engineering. FROM THE CLINICAL EDITOR This team of scientists has established a unique 3D hydrogel culture system as a model for the development of cardiac dysrhythmia.
Collapse
|
38
|
Zou J, Salarian M, Chen Y, Veenstra R, Louis CF, Yang JJ. Gap junction regulation by calmodulin. FEBS Lett 2014; 588:1430-8. [PMID: 24440348 DOI: 10.1016/j.febslet.2014.01.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 01/09/2014] [Accepted: 01/10/2014] [Indexed: 10/25/2022]
Abstract
Intracellular Ca(2+) activated calmodulin (CaM) inhibits gap junction channels in the low nanomolar to high micromolar range of [Ca(2+)]i. This regulation plays an essential role in numerous cellular processes that include hearing, lens transparency, and synchronized contractions of the heart. Previous studies have indicated that gap junction mediated cell-to-cell communication was inhibited by CaM antagonists. More recent evidence indicates a direct role of CaM in regulating several members of the connexin family. Since the intracellular loop and carboxyl termini of connexins are largely "invisible" in electron microscopy and X-ray crystallographic structures due to disorder in these domains, peptide models encompassing the putative CaM binding sites of several intracellular domains of connexins have been used to identify the Ca(2+)-dependent CaM binding sites of these proteins. This approach has been used to determine the CaM binding affinities of peptides derived from a number of different connexin-subfamilies.
Collapse
Affiliation(s)
- Juan Zou
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30303, United States
| | - Mani Salarian
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30303, United States
| | - Yanyi Chen
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30303, United States
| | - Richard Veenstra
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY 13210, United States
| | - Charles F Louis
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, United States.
| | - Jenny J Yang
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30303, United States.
| |
Collapse
|
39
|
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: 289] [Impact Index Per Article: 26.3] [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.
Collapse
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
| | | | | | | | | | | |
Collapse
|
40
|
Wang N, De Bock M, Decrock E, Bol M, Gadicherla A, Bultynck G, Leybaert L. Connexin targeting peptides as inhibitors of voltage- and intracellular Ca2+-triggered Cx43 hemichannel opening. Neuropharmacology 2013; 75:506-16. [DOI: 10.1016/j.neuropharm.2013.08.021] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 08/19/2013] [Accepted: 08/20/2013] [Indexed: 12/21/2022]
|
41
|
Rutter GA, Hodson DJ. Minireview: intraislet regulation of insulin secretion in humans. Mol Endocrinol 2013; 27:1984-95. [PMID: 24243488 PMCID: PMC5426601 DOI: 10.1210/me.2013-1278] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 10/23/2013] [Indexed: 12/25/2022] Open
Abstract
The higher organization of β-cells into spheroid structures termed islets of Langerhans is critical for the proper regulation of insulin secretion. Thus, rodent β-cells form a functional syncytium that integrates and propagates information encoded by secretagogues, producing a "gain-of-function" in hormone release through the generation of coordinated cell-cell activity. By contrast, human islets possess divergent topology, and this may have repercussions for the cell-cell communication pathways that mediate the population dynamics underlying the intraislet regulation of insulin secretion. This is pertinent for type 2 diabetes mellitus pathogenesis, and its study in rodent models, because environmental and genetic factors may converge on these processes in a species-specific manner to precipitate the defective insulin secretion associated with glucose intolerance. The aim of the present minireview is therefore to discuss the structural and functional underpinnings that influence insulin secretion from human islets, and the possibility that dyscoordination between individual β-cells may play an important role in some forms of type 2 diabetes mellitus.
Collapse
Affiliation(s)
- Guy A Rutter
- Section Cell Biology, Department of Medicine, Imperial College London, London SW7 2AZ, United Kingdom. ; or Professor Guy A. Rutter, Section of Cell Biology, Department of Medicine, Imperial College London, London SW7 2AZ, United Kingdom. E-mail:
| | | |
Collapse
|
42
|
De Bock M, Kerrebrouck M, Wang N, Leybaert L. Neurological manifestations of oculodentodigital dysplasia: a Cx43 channelopathy of the central nervous system? Front Pharmacol 2013; 4:120. [PMID: 24133447 PMCID: PMC3783840 DOI: 10.3389/fphar.2013.00120] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 09/02/2013] [Indexed: 12/30/2022] Open
Abstract
The coordination of tissue function is mediated by gap junctions (GJs) that enable direct cell–cell transfer of metabolic and electric signals. GJs are formed by connexins of which Cx43 is most widespread in the human body. In the brain, Cx43 GJs are mostly found in astroglia where they coordinate the propagation of Ca2+ waves, spatial K+ buffering, and distribution of glucose. Beyond its role in direct intercellular communication, Cx43 also forms unapposed, non-junctional hemichannels in the plasma membrane of glial cells. These allow the passage of several neuro- and gliotransmitters that may, combined with downstream paracrine signaling, complement direct GJ communication among glial cells and sustain glial-neuronal signaling. Mutations in the GJA1 gene encoding Cx43 have been identified in a rare, mostly autosomal dominant syndrome called oculodentodigital dysplasia (ODDD). ODDD patients display a pleiotropic phenotype reflected by eye, hand, teeth, and foot abnormalities, as well as craniofacial and bone malformations. Remarkably, neurological symptoms such as dysarthria, neurogenic bladder (manifested as urinary incontinence), spasticity or muscle weakness, ataxia, and epilepsy are other prominent features observed in ODDD patients. Over 10 mutations detected in patients diagnosed with neurological disorders are associated with altered functionality of Cx43 GJs/hemichannels, but the link between ODDD-related abnormal channel activities and neurologic phenotype is still elusive. Here, we present an overview on the nature of the mutants conveying structural and functional changes of Cx43 channels and discuss available evidence for aberrant Cx43 GJ and hemichannel function. In a final step, we examine the possibilities of how channel dysfunction may lead to some of the neurological manifestations of ODDD.
Collapse
Affiliation(s)
- Marijke De Bock
- Physiology Group, Department of Basic Medical Sciences, Ghent University Ghent, Belgium
| | | | | | | |
Collapse
|
43
|
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.
Collapse
|
44
|
Zhang SS, Shaw RM. Multilayered regulation of cardiac ion channels. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1833:876-85. [PMID: 23103513 PMCID: PMC3568256 DOI: 10.1016/j.bbamcr.2012.10.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 10/12/2012] [Accepted: 10/12/2012] [Indexed: 12/27/2022]
Abstract
Essential to beat-to-beat heart function is the ability for cardiomyocytes to propagate electrical excitation and generate contractile force. Both excitation and contractility depend on specific ventricular ion channels, which include the L-type calcium channel (LTCC) and the connexin 43 (Cx43) gap junction. Each of these two channels is localized to a distinct subdomain of the cardiomyocyte plasma membrane. In this review, we focus on regulatory mechanisms that govern the lifecycles of LTCC and Cx43, from their biogenesis in the nucleus to directed delivery to T-tubules and intercalated discs, respectively. We discuss recent findings on how alternative promoter usage, tissue-specific transcription, and alternative splicing determine precise ion channel expression levels within a cardiomyocyte. Moreover, recent work on microtubule and actin-dependent trafficking for Cx43 and LTCC are introduced. Lastly, we discuss how human cardiac disease phenotypes can be attributed to defects in distinct mechanisms of channel regulation at the level of gene expression and channel trafficking. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Cardiac Pathways of Differentiation, Metabolism and Contraction.
Collapse
Affiliation(s)
- Shan-Shan Zhang
- University of California, San Francisco, San Francisco, CA 94158, USA
| | | |
Collapse
|
45
|
Sahu G, Bera AK. Contribution of intracellular calcium and pH in ischemic uncoupling of cardiac gap junction channels formed of connexins 43, 40, and 45: a critical function of C-terminal domain. PLoS One 2013; 8:e60506. [PMID: 23536911 PMCID: PMC3607587 DOI: 10.1371/journal.pone.0060506] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 02/26/2013] [Indexed: 11/19/2022] Open
Abstract
Ischemia is known to inhibit gap junction (GJ) mediated intercellular communication. However the detail mechanisms of this inhibition are largely unknown. In the present study, we determined the vulnerability of different cardiac GJ channels formed of connexins (Cxs) 43, 40, and 45 to simulated ischemia, by creating oxygen glucose deprived (OGD) condition. 5 minutes of OGD decreased the junctional conductance (Gj) of Cx43, Cx40 and Cx45 by 53±3%, 64±1% and 85±2% respectively. Reduction of Gj was prevented completely by restricting the change of both intracellular calcium ([Ca(2+)]i) and pH (pHi) with potassium phosphate buffer. Clamping of either [Ca(2+)]i or pHi, through BAPTA (2 mM) or HEPES (80 mM) respectively, offered partial resistance to ischemic uncoupling. Anti-calmodulin antibody attenuated the uncoupling of Cx43 and Cx45 significantly but not of Cx40. Furthermore, OGD could reduce only 26±2% of Gj in C-terminus (CT) truncated Cx43 (Cx43-Δ257). Tethering CT of Cx43 to the CT-truncated Cx40 (Cx40-Δ249), and Cx45 (Cx45-Δ272) helped to resist OGD mediated uncoupling. Moreover, CT domain played a significant role in determining the junction current density and plaque diameter. Our results suggest; OGD mediated uncoupling of GJ channels is primarily due to elevated [Ca(2+)]i and acidic pHi, though the latter contributes more. Among Cx43, Cx40 and Cx45, Cx43 is the most resistant to OGD while Cx45 is the most sensitive one. CT of Cx43 has major necessary elements for OGD induced uncoupling and it can complement CT of Cx40 and Cx45.
Collapse
Affiliation(s)
- Giriraj Sahu
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India
| | - Amal Kanti Bera
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India
- * E-mail:
| |
Collapse
|
46
|
Nagaraja S, Kapela A, Tsoukias NM. Intercellular communication in the vascular wall: a modeling perspective. Microcirculation 2012; 19:391-402. [PMID: 22340204 DOI: 10.1111/j.1549-8719.2012.00171.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Movement of ions (Ca(2+) , K(+) , Na(+) , and Cl(-) ) and second messenger molecules like inositol 1, 4, 5-trisphosphate inside and in between different cells is the basis of many signaling mechanisms in the microcirculation. In spite of the vast experimental efforts directed toward evaluation of these fluxes, it has been a challenge to establish their roles in many essential microcirculatory phenomena. Recently, detailed theoretical models of calcium dynamics and plasma membrane electrophysiology have emerged to assist in the quantification of these intra and intercellular fluxes and enhance understanding of their physiological importance. This perspective reviews selected models relevant to estimation of such intra and intercellular ionic and second messenger fluxes and prediction of their relative significance to a variety of vascular phenomena, such as myoendothelial feedback, conducted responses, and vasomotion.
Collapse
Affiliation(s)
- Sridevi Nagaraja
- Department of Biomedical Engineering, Florida International University, Miami, Florida 33174, USA
| | | | | |
Collapse
|
47
|
Haq N, Grose D, Ward E, Chiu O, Tigue N, Dowell SJ, Powell AJ, Chen MX. A high-throughput assay for connexin 43 (Cx43, GJA1) gap junctions using codon-optimized aequorin. Assay Drug Dev Technol 2012; 11:93-100. [PMID: 23046406 DOI: 10.1089/adt.2012.469] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Gap junctions (GJs) are intercellular channels which are composed of the connexin family of proteins that allow electrical and chemical communications and synchronization in tissue ensembles. Evidence suggests that pharmaceutical modulators of these channels may have therapeutic potential or carry undesired liability. In this report, we exogenously expressed human connexin 43 (Cx43, GJA1) and demonstrated functionality in a 96-well flow cytometry assay detecting intercellular transfer of the calcein dye. We have designed a 384-well high-throughput method for detecting the transfer of calcium between HeLa cells expressing Cx43. In this assay, donor cells coexpress Cx43 and the α1A adrenergic Gα-coupled receptor, while recipient cells coexpress Cx43 and the cytoplasmic version of the calcium-sensitive luminescent protein aequorin enhanced by codon optimization (cytoAeq). The two cell populations were mixed, dispensed to 384-well plates, and incubated for 3 h to allow the formation of GJs. Activation of α1A by epinephrine in donor cells led to dose-dependent calcium increases in recipient cells, which were detected by measuring the intensity of aequorin luminescence. The response was dependent on the expression of Cx43 and inhibited by the GJ blocker 18α-glycyrrhetinic acid, suggesting Cx43 GJ-mediated activity. In a parallel experiment with capsaicin and the TrpV1 ion channel in place of phenylephrine and α1A, a similar magnitude of difference in the maximal calcium response was detected in both donor and recipient cells, suggesting that calcium is likely the permeant ion through the GJ. This assay may pave the way for high-throughput screening of GJ modulators for drug discovery.
Collapse
Affiliation(s)
- Nazia Haq
- Biological Reagents and Assay Development, GlaxoSmithKline R&D, Stevenage, United Kingdom
| | | | | | | | | | | | | | | |
Collapse
|
48
|
Abstract
Intercellular calcium (Ca(2+)) waves (ICWs) represent the propagation of increases in intracellular Ca(2+) through a syncytium of cells and appear to be a fundamental mechanism for coordinating multicellular responses. ICWs occur in a wide diversity of cells and have been extensively studied in vitro. More recent studies focus on ICWs in vivo. ICWs are triggered by a variety of stimuli and involve the release of Ca(2+) from internal stores. The propagation of ICWs predominately involves cell communication with internal messengers moving via gap junctions or extracellular messengers mediating paracrine signaling. ICWs appear to be important in both normal physiology as well as pathophysiological processes in a variety of organs and tissues including brain, liver, retina, cochlea, and vascular tissue. We review here the mechanisms of initiation and propagation of ICWs, the key intra- and extracellular messengers (inositol 1,4,5-trisphosphate and ATP) mediating ICWs, and the proposed physiological functions of ICWs.
Collapse
Affiliation(s)
- Luc Leybaert
- Department of Basic Medical Sciences, Physiology Group, Faculty of Medicine & Health Sciences, Ghent University, Ghent, Belgium.
| | | |
Collapse
|
49
|
Tveito A, Lines GT, Edwards AG, Maleckar MM, Michailova A, Hake J, McCulloch A. Slow Calcium-Depolarization-Calcium waves may initiate fast local depolarization waves in ventricular tissue. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 110:295-304. [PMID: 22841534 DOI: 10.1016/j.pbiomolbio.2012.07.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Accepted: 07/16/2012] [Indexed: 10/28/2022]
Abstract
Intercellular calcium waves in cardiac myocytes are a well-recognized, if incompletely understood, phenomenon. In a variety of preparations, investigators have reported multi-cellular calcium waves or triggered propagated contractions, but the mechanisms of propagation and pathological importance of these events remain unclear. Here, we review existing experimental data and present a computational approach to investigate the mechanisms of multi-cellular calcium wave propagation. Over the past 50 years, the standard modeling paradigm for excitable cardiac tissue has seen increasingly detailed models of the dynamics of individual cells coupled in tissue solely by intercellular and interstitial current flow. Although very successful, this modeling regime has been unable to capture two important phenomena: 1) the slow intercellular calcium waves observed experimentally, and 2) how intercellular calcium events resulting in delayed after depolarizations at the cellular level could overcome a source-sink mismatch to initiate depolarization waves in tissue. In this paper, we introduce a mathematical model with subcellular spatial resolution, in which we allow both inter- and intracellular current flow and calcium diffusion. In simulations of coupled cells employing this model, we observe: a) slow inter-cellular calcium waves propagating at about 0.1 mm/s, b) faster Calcium-Depolarization-Calcium (CDC) waves, traveling at about 1 mm/s, and c) CDC-waves that can set off fast depolarization-waves (50 cm/s) in tissue with varying gap-junction conductivity.
Collapse
Affiliation(s)
- Aslak Tveito
- Center for Biomedical Computing, Simula Research Laboratory, Norway
| | | | | | | | | | | | | |
Collapse
|
50
|
Regulation of Cx45 hemichannels mediated by extracellular and intracellular calcium. Pflugers Arch 2012; 464:249-59. [DOI: 10.1007/s00424-012-1133-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 06/13/2012] [Accepted: 06/15/2012] [Indexed: 12/15/2022]
|