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Estell EG, Murphy LA, Silverstein AM, Tan AR, Shah RP, Ateshian GA, Hung CT. Fibroblast-like synoviocyte mechanosensitivity to fluid shear is modulated by interleukin-1α. J Biomech 2017; 60:91-99. [PMID: 28716465 PMCID: PMC5788292 DOI: 10.1016/j.jbiomech.2017.06.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 06/10/2017] [Accepted: 06/13/2017] [Indexed: 11/29/2022]
Abstract
Fibroblast-like synoviocytes (FLS) reside in the synovial membrane of diarthrodial joints and are exposed to a dynamic fluid environment that presents both physical and chemical stimuli. The ability of FLS to sense and respond to these stimuli plays a key role in their normal function, and is implicated in the alterations to function that occur in osteoarthritis (OA). The present work characterizes the response of FLS to fluid flow-induced shear stress via real-time calcium imaging, and tests the hypothesis that this response is modulated by interleukin-1α (IL-1α), a cytokine elevated in OA. FLS demonstrated a robust calcium signaling response to fluid shear that was dose dependent upon stress level and required both external and internal calcium sources. Preconditioning with 10ng/mL IL-1α for 24h heightened this shear stress response by significantly increasing the percent of responding cells and peak magnitude, while significantly decreasing the time for a peak to occur. Intercellular communication via gap junctions was found to account for a portion of the FLS population response in normal conditions, and was significantly increased by IL-1α preconditioning. IL-1α was also found to significantly increase average length and incidence of the primary cilium, an organelle commonly implicated in shear mechanosensing. These findings suggest that the elevated levels of IL-1α found in the OA environment heighten FLS sensitivity to fluid shear by altering both intercellular communication and individual cell sensitivity, which could affect downstream functions and contribute to progression of the disease state.
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Affiliation(s)
- Eben G Estell
- Columbia University, Department of Biomedical Engineering, New York, NY, United States
| | - Lance A Murphy
- Columbia University, Department of Biomedical Engineering, New York, NY, United States
| | - Amy M Silverstein
- Columbia University, Department of Biomedical Engineering, New York, NY, United States
| | - Andrea R Tan
- Columbia University, Department of Biomedical Engineering, New York, NY, United States
| | - Roshan P Shah
- Columbia University, Department of Orthopedic Surgery, New York, NY, United States
| | - Gerard A Ateshian
- Columbia University, Department of Biomedical Engineering, New York, NY, United States
| | - Clark T Hung
- Columbia University, Department of Biomedical Engineering, New York, NY, United States.
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2
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Alberto AVP, Bonavita AG, Fidalgo-Neto AA, Berçot F, Alves LA. Single-cell Microinjection for Cell Communication Analysis. J Vis Exp 2017. [PMID: 28287521 DOI: 10.3791/50836] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Gap junctions are intercellular channels that allow the communication of neighboring cells. This communication depends on the contribution of a hemichannel by each neighboring cell to form the gap junction. In mammalian cells, the hemichannel is formed by six connexins, monomers with four transmembrane domains and a C and N terminal within the cytoplasm. Gap junctions permit the exchange of ions, second messengers, and small metabolites. In addition, they have important roles in many forms of cellular communication within physiological processes such as synaptic transmission, heart contraction, cell growth and differentiation. We detail how to perform a single-cell microinjection of Lucifer Yellow to visualize cellular communication via gap-junctions in living cells. It is expected that in functional gap junctions, the dye will diffuse from the loaded cell to the connected cells. It is a very useful technique to study gap junctions since you can evaluate the diffusion of the fluorescence in real time. We discuss how to prepare the cells and the micropipette, how to use a micromanipulator and inject a low molecular weight fluorescent dye in an epithelial cell line.
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Affiliation(s)
| | - André G Bonavita
- Institute Oswaldo Cruz, Laboratory of Cellular Communication, Oswaldo Cruz Foundation
| | | | - Filipe Berçot
- Institute Oswaldo Cruz, Laboratory of Cellular Communication, Oswaldo Cruz Foundation
| | - Luiz A Alves
- Institute Oswaldo Cruz, Laboratory of Cellular Communication, Oswaldo Cruz Foundation;
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3
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Gap junctions and connexin hemichannels in the regulation of haemostasis and thrombosis. Biochem Soc Trans 2016; 43:489-94. [PMID: 26009196 DOI: 10.1042/bst20150055] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Platelets are involved in the maintenance of haemostasis but their inappropriate activation leads to thrombosis, a principal trigger for heart attack and ischaemic stroke. Although platelets circulate in isolation, upon activation they accumulate or aggregate together to form a thrombus, where they function in a co-ordinated manner to prevent loss of blood and control wound repair. Previous report (1) indicates that the stability and functions of a thrombus are maintained through sustained, contact-dependent signalling between platelets. Given the role of gap junctions in the co-ordination of tissue responses, it was hypothesized that gap junctions may be present within a thrombus and mediate intercellular communication between platelets. Therefore studies were performed to explore the presence and functions of connexins in platelets. In this brief review, the roles of hemichannels and gap junctions in the control of thrombosis and haemostasis and the future directions for this research will be discussed.
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Yu F, Yan H, Nie W, Zhu J. Connexin43 knockdown in bone marrow‑derived dendritic cells by small interfering RNA leads to a diminished T-cell stimulation. Mol Med Rep 2015; 13:895-900. [PMID: 26648560 DOI: 10.3892/mmr.2015.4593] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 08/25/2015] [Indexed: 11/06/2022] Open
Abstract
Dendritic cells, the most powerful type of antigen‑presenting cells, have the unique ability to induce primary immune responses. Connexin43 expression is upregulated to increase gap junctions when immune cells are exposed to inflammatory factors. The present study applied small‑interfering RNA (siRNA) to decrease connexin43 expression. The results showed that silencing of connexin43 using siRNA resulted in arrest of bone marrow‑derived dendritic cell (BM‑DC) maturation as evidenced by reduced expression of major histocompatibility complex II, CD40, CD80 and CD86. Functionally, connexin43‑silenced BM‑DC showed a markedly decreased capability to induce T-cell stimulation. In conclusion, the present study demonstrated that antigens present on BM‑DCs can be suppressed by connexin43 knockdown in BM‑DCs. The present study therefore presented an effective method to modulate the immunology of BM‑DCs.
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Affiliation(s)
- Fuling Yu
- Cardiovascular Department, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China
| | - Hui Yan
- Cardiovascular Department, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China
| | - Wencheng Nie
- Cardiovascular Department, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China
| | - Jianhua Zhu
- Cardiovascular Department, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China
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Liu Y, Wen Q, Chen XL, Yang SJ, Gao L, Gao L, Zhang C, Li JL, Xiang XX, Wan K, Chen XH, Zhang X, Zhong JF. All-trans retinoic acid arrests cell cycle in leukemic bone marrow stromal cells by increasing intercellular communication through connexin 43-mediated gap junction. J Hematol Oncol 2015; 8:110. [PMID: 26446715 PMCID: PMC4597383 DOI: 10.1186/s13045-015-0212-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 09/28/2015] [Indexed: 01/28/2023] Open
Abstract
Background Gap junctional intercellular communication (GJIC) is typically decreased in malignant tumors. Gap junction is not presented between hematopoietic cells but occurred in bone marrow stromal cells (BMSCs). Connexin 43 (Cx43) is the major gap junction (GJ) protein; our previous study revealed that Cx43 expression and GJIC were decreased in acute leukemic BMSCs. All-trans retinoic acid (ATRA) increases GJIC in a variety of cancer cells and has been used to treat acute promyelocytic leukemia, but the effects of ATRA on leukemic BMSCs is unknown. In this study, we evaluated the potential effects of ATRA on cell cycle, proliferation, and apoptosis of leukemic BMSCs. Effects of ATRA on Cx43 expression and GJIC were also examined. Methods Human BMSCs obtained from 25 patients with primary acute leukemia, and 10 normal healthy donors were cultured. Effects of ATRA on cell cycle, cell proliferation, and apoptosis were examined with or without co-treatment with amphotericin-B. Cx43 expression was examined at both the mRNA and protein expression levels. GJIC was examined by using a dye transfer assay and measuring the rate of fluorescence recovery after photobleaching (FRAP). Results ATRA arrested the cell cycle progression, inhibited cell growth, and increased apoptosis in leukemic BMSCs. Both Cx43 expression and GJIC function were increased by ATRA treatment. Most of the observed effects mediated by ATRA were abolished by amphotericin-B pretreatment. Conclusions ATRA arrests cell cycle progression in leukemic BMSCs, likely due to upregulating Cx43 expression and enhancing GJIC function. Electronic supplementary material The online version of this article (doi:10.1186/s13045-015-0212-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yao Liu
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China. .,Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.
| | - Qin Wen
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Xue-Lian Chen
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.
| | - Shi-Jie Yang
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Lei Gao
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Li Gao
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Cheng Zhang
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Jia-Li Li
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Xi-Xi Xiang
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Kai Wan
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Xing-Hua Chen
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Xi Zhang
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Jiang-Fan Zhong
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.
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Liu Y, Zhang X, Li ZJ, Chen XH. Up-regulation of Cx43 expression and GJIC function in acute leukemia bone marrow stromal cells post-chemotherapy. Leuk Res 2009; 34:631-40. [PMID: 19910046 DOI: 10.1016/j.leukres.2009.10.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 09/10/2009] [Accepted: 10/14/2009] [Indexed: 10/20/2022]
Abstract
Gap junction intercellular communication (GJIC) among bone marrow stromal cells (BMSCs) most frequently occurs through a channel composed of connexin43 (Cx43). Dysregulation of connexin expression is believed to have a role in carcinogenesis. In earlier work, we found that in acute leukemia BMSCs, expression of Cx43 and functioning GJIC declined. However, there has been no evaluation of whether GJIC in BMSCs in complete remission (CR) post-chemotherapy is different from GJIC pre-chemotherapy. We studied Cx43 expression and tested GJIC function in human bone marrow cultures under different physiological and pathological conditions. To assay Cx43 expression we used immunocytochemistry, laser scan confocal microscopy (LSCM), flow cytometry and RT-PCR. The results showed that the expression level of Cx43 and its mRNA in acute leukemia BMSCs post-chemotherapy was significantly higher and similar to normal levels than in primary acute leukemia BMSCs (p<0.01). Functional tests in cultures using dye transfer and fluorescence recovery after photobleaching (FRAP) assays showed that the function of GJIC in acute leukemia BMSCs was significantly improved following effective chemotherapy. Our findings suggest Cx43 and GJIC might be involved in the courses of occurrence, development and termination of acute leukemia, and effective chemotherapy could improve Cx43 expression and GJIC function that were dysfunctional prior to treatment.
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Affiliation(s)
- Yao Liu
- Department of Hematology, Xinqiao Hospital, The Third Military Medical University, Shapingba District, Xinqiao Street, Chongqing 400037, China
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7
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A model system to study Connexin 43 in the immune system. Mol Immunol 2009; 46:2938-46. [PMID: 19608277 DOI: 10.1016/j.molimm.2009.06.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 06/11/2009] [Accepted: 06/18/2009] [Indexed: 11/21/2022]
Abstract
Connexin 43 (Cx43) is the predominant gap junction protein expressed in immune cells. Previous manuscripts have stated that gap junctions may play a role in antigen cross-presentation, dendritic cell maturation, T cell development, and regulatory T cell function. Many of these previous studies were performed in vitro. In vivo studies were not directly possible in adult mice because Cx43-/- mice die shortly after birth due to a cardiac malformation. To overcome these drawbacks, we have developed a mouse model that deletes Cx43 in the immune system while maintaining normal cardiac function. In our model, irradiated CD45.1+ wild-type mice were reconstituted with Cx43WT, Cx43+/-, or Cx43-/- hematopoietic fetal liver cells that were derived from CD45.2+ mice. The presence of CD45.2 allowed us to identify and track the donor cells following reconstitution. We determined that Cx43+/- and Cx43-/- hematopoietic cells were able to reconstitute irradiated mice as well as Cx43WT cells. Reconstitution was nearly 100% in the thymus and over 90% in the spleen. There appeared to be no difference in thymocyte development or in the ability of lymphocytes to transmigrate to peripheral lymphoid organs. However in response to inflammation, Cx43+/- radiation chimeras had increased peritoneal infiltration compared to Cx43WT and Cx43-/- groups. IgG responses were normal in all groups but the Cx43-/- reconstituted mice had an elevated IgM response. Our data suggests that Cx43 may not be involved in the normal development of the immune system but may regulate certain effector functions in vivo.
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8
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Handel A, Yates A, Pilyugin SS, Antia R. Sharing the burden: antigen transport and firebreaks in immune responses. J R Soc Interface 2008; 6:447-54. [PMID: 18708323 DOI: 10.1098/rsif.2008.0258] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Communication between cells is crucial for immune responses. An important means of communication during viral infections is the presentation of viral antigen on the surface of an infected cell. Recently, it has been shown that antigen can be shared between infected and uninfected cells through gap junctions, connexin-based channels, that allow the transport of small molecules. The uninfected cell receiving antigen can present it on its surface. Cells presenting viral antigen are detected and killed by cytotoxic T lymphocytes. The killing of uninfected cells can lead to increased immunopathology. However, the immune response might also profit from killing those uninfected bystander cells. One benefit might be the removal of future 'virus factories'. Another benefit might be through the creation of 'firebreaks', areas void of target cells, which increase the diffusion time of free virions, making their clearance more likely. Here, we use theoretical models and simulations to explore how the mechanism of gap junction-mediated antigen transport (GMAT) affects the dynamics of the virus and immune response. We show that under the assumption of a well-mixed system, GMAT leads to increased immunopathology, which always outweighs the benefit of reduced virus production due to the removal of future virus factories. By contrast, a spatially explicit model leads to quite different results. Here we find that the firebreak mechanism reduces both viral load and immunopathology. Our study thus shows the potential benefits of GMAT and illustrates how spatial effects may be crucial for the quantitative understanding of infection dynamics and immune responses.
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Affiliation(s)
- Andreas Handel
- Department of Biology, Emory University, Atlanta, GA 30322, USA
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9
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Handel A, Yates A, Pilyugin SS, Antia R. Gap junction-mediated antigen transport in immune responses. Trends Immunol 2007; 28:463-6. [DOI: 10.1016/j.it.2007.08.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Revised: 08/14/2007] [Accepted: 08/14/2007] [Indexed: 12/26/2022]
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Abstract
This article continues the ongoing debate around models of the immune system. Earlier contributors have paid much attention to the various processes that lead to adaptive immune system aggression or tolerance. They have often based their discussions around facts that have been established by experimental investigation. However, both the observation and interpretation of these facts have been influenced by the function--or system goal--that is believed to have generated them. The perception of this function (of all or part of the immune system) is influenced by long established theories in immunology (e.g. horror autotoxicus, clonal deletion in utero, pathogen elimination, clonal selection, auto-immunity and so on) which, for many, have become enshrined as facts. One function that has had less consideration and has not been extensively investigated is the maintenance of tissue homeostasis. When the immune system is viewed from this perspective, the facts invite alternative interpretations. Whilst this perspective may not necessarily be the only valid one, let alone a correct one, viewing things this way--at least briefly--might help to expose hidden assumptions. It also emphasizes that the immune system is a system and, as such, it can by analysed through the principles of general systems theory.
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Gomes P, Srinivas SP, Vereecke J, Himpens B. Gap junctional intercellular communication in bovine corneal endothelial cells. Exp Eye Res 2006; 83:1225-37. [PMID: 16938292 DOI: 10.1016/j.exer.2006.06.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 05/18/2006] [Accepted: 06/26/2006] [Indexed: 11/15/2022]
Abstract
Gap junctions and/or paracrine mediators, such as ATP, mediate intercellular communication (IC) in non-excitable cells. This study investigates the contribution of gap junctions toward IC during propagation of Ca(2+) waves in cultured bovine corneal endothelial cells (BCEC) elicited by applying a point mechanical stimulus to a single cell in a confluent monolayer. Changes in [Ca(2+)](i) were visualized using the fluorescent dye Fluo-4. The area reached by the Ca(2+) wave, called the active area (AA), was determined as a measure of efficacy of IC. RT-PCR and Western blotting showed expression of Cx43, a major form of connexin, in BCEC. In scrape-loading (using lucifer yellow) and fluorescence recovery after photobleaching (FRAP; using carboxyfluorescein) protocols, significant dye transfer of the hydrophilic dyes was evident indicating functional gap junctional IC (GJIC) in BCEC. Gap27 (300 microM), a connexin mimetic peptide that blocks gap junctions formed by Cx43, reduced the fluorescence recovery in FRAP experiments by 19%. Gap27 also reduced the active area of the Ca(2+) wave induced by point mechanical stimulation from 73,689 microm(2) to 26,936 microm(2), implying that GJIC contribution to the spread of the wave is at least approximately 63%. Inhibitors of ATP-mediated paracrine IC (PIC), such as a combination of apyrase VI and apyrase VII (5U/ml each; exogenous ATPases), suramin (200 microM; P2Y antagonist), or Gap26 (300 microM; blocker of Cx43 hemichannels) reduced the active area by 91%, 67%, and 55%, respectively. Therefore, estimating the contribution of GJIC from the residual active area after PIC inhibition appears to suggest that GJIC contributes no more than approximately 9% towards the active area of the Ca(2+) wave. Gap27 did not affect the enhancement in active area induced by ARL-67156 (200 microM, ectonucleotidase inhibitor), ATP release induced by point mechanical stimulation, and zero [Ca(2+)](o)-induced lucifer yellow uptake, indicating that the peptide has no influence on PIC. Exposure to Gap27 in the presence of PIC inhibitors led to a significant further inhibition of the Ca(2+) wave. The finding that the residual active area after inhibition of PIC by apyrases was much smaller than the reduction of the active area by Gap27, provides evidence for interaction between GJIC and PIC. These findings together suggest that functional gap junctions are present in BCEC, that both GJIC and PIC contribute significantly to IC, and that the two pathways interact.
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Affiliation(s)
- Priya Gomes
- Laboratory of Physiology, KU Leuven, Campus Gasthuisberg O/N, Box 802, Herestraat 49, B-3000 Leuven, Belgium
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12
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Brelinska R, Malinska A. Homing of hemopoietic precursor cells to the fetal rat thymus: intercellular contact-controlled cell migration and development of the thymic microenvironment. Cell Tissue Res 2005; 322:393-405. [PMID: 16133143 DOI: 10.1007/s00441-005-1079-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2004] [Accepted: 12/22/2004] [Indexed: 10/25/2022]
Abstract
Colonization of rat thymic anlage by the first wave of hemopoietic precursor cells (HPc) was investigated by means of transmission electron microscopy and immunocytochemistry. HPc began migration into the thymic anlage between 13 and 13.5 gestation days (GD), terminated colonization at about GD 16, and migrated sequentially through the two compartments of the thymic anlage under the control of typical populations of stromal cells. First, HPc migrated through the external compartment of the perithymic mesenchyme, tightly interconnected with fibroblasts. The type of junctions between the cells indicated that the fibroblasts played a role in the control of HPc trafficking and in their entrance to the epithelial compartment. The second stage of colonization was initiated by the entrance of HPc to the epithelial compartment and their interaction with thymic epithelial cells (TECs). Based on morphological criteria, two populations of HPc were distinguished that colonized the anlage at various stages of its development. The predominant population with ultrastructural traits common to thymocytes "homed" into the epithelial type primordium. A small number of HPc, identified by protein S-100 expression and by Birbeck's granules as precursors of dendritic cells, colonized lymphoepithelial anlage in which subsets of cortical and medullary TECs could be distinguished. Thymocyte migration and their reciprocal interactions with cortical TECs differed from the trafficking of dendritic cells toward the medulla. The results demonstrated the influence of maturing thymocytes on the development of cortical epithelial cells and the dynamic organization of the medullary microenvironment with direct involvement of dendritic cells.
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Affiliation(s)
- Renata Brelinska
- Department of Histology and Embryology, University of Medical Sciences, 60-781, Poznań, Poland.
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13
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Vucević D, Colić M, Gasić S, Vasilijić S. [Thymic nurse cells--a specialized thymic microenvironment]. VOJNOSANIT PREGL 2005; 62:133-45. [PMID: 15787167 DOI: 10.2298/vsp0502133v] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
<zakljucak> Vise od dve decenije nakon prvog opisa, TNC su i dalje velika nepoznanica i potrebno je jos mnogo istrazivanja pre nego sto budemo bili u mogucnosti da definisemo preciznu ulogu ovih celija u razvoju T-limfocita. Mnoga od dosadasnjih saznanja ukazuju da se timociti u kontaktu sa TNC nalaze na prekretnici u svom razvojnom putu: ili ce biti uklonjeni indukcijom apoptoze ili ce nastaviti svoj razvoj i dalje sazrevanje. Brojna pitanja su za sada bez odgovora, a medju njima su dva posebno intrigantna. Koja je razlika izmedju timocita koji se vezuju za TNC i onih koji to ne cine? Koja je razlika izmedju populacije adherentnih timocita koji su selektivno internalizovani i onih koji su iskljuceni iz procesa internalizacije? Buduca istrazivanja kretanja timocita ka, unutar i van TNC ce verujemo pruziti dragocene informacije o ovoj fazi u razvoju T-limfocita. Nezavisno od toga sta ce buducnost pokazati o pravoj ulozi TNC, jedinstven kompleks koji ove celije formiraju sa timocitima je vrlo neobican, uzbudljiv i zagonetan bioloski fenomen.
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Affiliation(s)
- Dragana Vucević
- Vojnomedicinska akademija, Institut za medicinska istrazivanja, Beograd.
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14
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Abstract
Gap junctional communication plays a central role in the maintenance of cellular homeostasis by allowing the passage of small molecules between adjacent cells. Gap junctions are composed of a family of proteins termed connexins. During preimplantation development several connexin proteins are expressed and assembled into gap junctions in the plasma membrane at compaction but the functional significance of connexin diversity remains controversial. Although, many of the connexin genes have been disrupted using homologous recombination in embryonic stem cells to obtain unique phenotypes, none of these studies has demonstrated a specific role for connexins during preimplantation development in the null mutants. This review surveys evidence for the involvement of gap junctional communication during embryo development highlighting discrepancies in the literature. Although some evidence suggests that gap junctions may be dispensable during preimplantation development this is difficult to envisage particularly for the process of cavitation and the maintenance of homeostasis between the differentiated trophectoderm cells and the pluripotent inner cell mass cells of the blastocyst.
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15
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Farahani R, Pina-Benabou MH, Kyrozis A, Siddiq A, Barradas PC, Chiu FC, Cavalcante LA, Lai JCK, Stanton PK, Rozental R. Alterations in metabolism and gap junction expression may determine the role of astrocytes as ?good samaritans? or executioners. Glia 2005; 50:351-361. [PMID: 15846800 DOI: 10.1002/glia.20213] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Our knowledge of astroglia and their physiological and pathophysiological role(s) in the central nervous system (CNS) has grown during the past decade, revealing a complex picture. It is becoming increasingly clear that glia play a significant role in the homeostasis and function of the CNS and that neurons should no longer be considered the only cell type that responds, both rapidly and slowly, to electrochemical activity. We discuss recent advances in the field with an emphasis on the impact of hypoxia and ischemia on astrocytic metabolism and the functional relationship between glucose metabolism and gap junctions in astrocytes. We also address the controversy over whether astrocytic gap junctions mediate protection or killing of neurons during or after hypoxic or ischemic insults.
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Affiliation(s)
- Reza Farahani
- Department of Pediatrics, Albert Einstein College of Medicine, Bronx, New York
| | - Mara H Pina-Benabou
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York
| | - Andreas Kyrozis
- Department of Neurology, Albert Einstein College of Medicine, Bronx, New York
| | - Ayesha Siddiq
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York
| | - Penha C Barradas
- Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fung-Chow Chiu
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, Georgia
| | - Leny A Cavalcante
- Instituto de Biofisica C. Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - James C K Lai
- Department of Pharmaceutical Sciences, College of Pharmacy, Idaho State University, Pocatello, Idaho
| | - Patric K Stanton
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York
- Department of Neurology, New York Medical College, Valhalla, New York
| | - Renato Rozental
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York
- Department of Obstetrics and Anesthesiology, New York Medical College, Valhalla, New York
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Fortes FSA, Pecora IL, Persechini PM, Hurtado S, Costa V, Coutinho-Silva R, Braga MBM, Silva-Filho FC, Bisaggio RC, De Farias FP, Scemes E, De Carvalho ACC, Goldenberg RCS. Modulation of intercellular communication in macrophages: possible interactions between GAP junctions and P2 receptors. J Cell Sci 2004; 117:4717-26. [PMID: 15331634 DOI: 10.1242/jcs.01345] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Gap junctions are connexin-formed channels that play an important role in intercellular communication in most cell types. In the immune system, specifically in macrophages, the expression of connexins and the establishment of functional gap junctions are still controversial issues. Macrophages express P2X(7) receptors that, once activated by the binding of extracellular ATP, lead to the opening of transmembrane pores permeable to molecules of up to 900 Da. There is evidence suggesting an interplay between gap junctions and P2 receptors in different cell systems. Thus, we used ATP-sensitive and -insensitive J774.G8 macrophage cell lines to investigate this interplay. To study junctional communication in J774-macrophage-like cells, we assessed cell-to-cell communication by microinjecting Lucifer Yellow. Confluent cultures of ATP-sensitive J774 cells (ATP-s cells) are coupled, whereas ATP-insensitive J774 cells (ATP-i cells), derived by overexposing J774 cells to extracellular ATP until they do not display the phenomenon of ATP-induced permeabilization, are essentially uncoupled. Western-blot and reverse-transcription polymerase chain reaction assays revealed that ATP-s and ATP-i cells express connexin43 (Cx43), whereas only ATP-s cells express the P2X(7) receptor. Accordingly, ATP-i cells did not display any detectable ATP-induced current under whole-cell patch-clamp recordings. Using immunofluorescence microscopy, Cx43 reactivity was found at the cell surface and in regions of cell-cell contact of ATP-s cells, whereas, in ATP-i cells, Cx43 immunoreactivity was only present in cytosolic compartments. Using confocal microscopy, it is shown here that, in ATP-s cells as well as in peritoneal macrophages, Cx43 and P2X(7) receptors are co-localized to the membrane of ATP-s cells and peritoneal macrophages.
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Affiliation(s)
- Fabio S A Fortes
- Institute of Biophysics Carlos Chagas Filho, UFRJ, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ 21941-590, Brazil
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Oviedo-Orta E, Howard Evans W. Gap junctions and connexin-mediated communication in the immune system. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1662:102-12. [PMID: 15033582 DOI: 10.1016/j.bbamem.2003.10.021] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2003] [Revised: 10/20/2003] [Accepted: 10/20/2003] [Indexed: 10/26/2022]
Abstract
Gap junctions and connexins are present in the immune system. In haematopoiesis, connexin 43, the most widely distributed gap junction protein, appears to be a key player in the development of progenitor cells and their communication with stromal cells. Connexin 43 is expressed by macrophages, neutrophils and mast cells. Lymphocytes also express connexin 43, and inhibition of gap junction channels in these cells by using highly specific connexin mimetic reagents has profound effects on immunoglobulin secretion and synthesis of cytokines. Lymphocytes and leukocytes also communicate directly in vitro with endothelial cells via gap junctions. Connexins are implicated in inflammatory reactions in a range of tissues. Their involvement in atherosclerotic plaque formation in the vascular system is also a current growth point in research, and could lead to the development of therapeutic interventions.
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Affiliation(s)
- Ernesto Oviedo-Orta
- Bristol Heart Institute, Bristol Royal Infirmary, Upper Maudlin Street, Bristol BS2 8HW, UK
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Mandelker L. The natural activities of cells, the role of reactive oxygen species, and their relation to antioxidants, nutraceuticals, botanicals, and other biologic therapies. Vet Clin North Am Small Anim Pract 2004; 34:39-66. [PMID: 15032125 DOI: 10.1016/j.cvsm.2003.09.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
There have been remarkable advances in molecular and cell biology that define the mechanisms of how various supplements function in and around cells. Current evidence strongly supports the probability that cellular functions and cellular responses that pertain to inflammation, disease, and life and death activity can be modulated with supplementation; however, the complexity of each individual's reaction and the vast differences in physiologic influences makes clinical research difficult in regard to clinical studies using antioxidant and biologic therapies. Not enough is known specifically about each supplement and its interactions with cells, nor is enough understood about how the body compensates or reacts to such applications. What works well in one individual or species might work differently in another. In addition, not all antioxidants are created equally, and discrepancies in purity and absorption can occur. It must also be determined whether or not less than optimum levels or infrequent usage will produce the same physiological effects. Not everyone--nor every species of animal--responds in the same manner to supplements, which might account for the variations in clinical research. The cellular effects of antioxidants and other supplements are well defined and meaningful, and their clinical application looks promising despite individual variations. Combinations of antioxidants are synergistic and support cellular functions, effects that are often not apparent with individual agents. Such combinations offer a variety of mechanisms for reducing oxygen metabolites in tissues, altering signaling pathways, and modulating transcription factors, and they might play key roles in reducing the damage afforded by ROS. It is the author's opinion that combinations of antioxidants are best suited for clinical application in modulating disease and reducing premature aging when caused by excessive free radical accumulation. Clinicians should approach clinical application of these supplements based on the best available scientific research and species-specific information available.
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Affiliation(s)
- Lester Mandelker
- Community Veterinary Hospital, 1631 W. Bay Drive, Largo, FL 33770, USA.
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Oviedo‐Orta E, Evans WH. Gap junctions and connexins: potential contributors to the immunological synapse. J Leukoc Biol 2002. [DOI: 10.1189/jlb.72.4.636] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
| | - W. Howard Evans
- Department of Medical Biochemistry and Wales Heart Research Institute, University of Wales College of Medicine, Cardiff, United Kingdom
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Montecino‐Rodriguez E, Dorshkind K. Regulation of hematopoiesis by gap junction‐mediated intercellular communication. J Leukoc Biol 2001. [DOI: 10.1189/jlb.70.3.341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Encarnacion Montecino‐Rodriguez
- Department of Pathology and Laboratory Medicine and the Jonsson Comprehensive Cancer Center, UCLA School of Medicine, Los Angeles, California
| | - Kenneth Dorshkind
- Department of Pathology and Laboratory Medicine and the Jonsson Comprehensive Cancer Center, UCLA School of Medicine, Los Angeles, California
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Abstract
The thymus gland is a central lymphoid organ in which bone marrow-derived T cell precursors undergo differentiation, eventually leading to migration of positively selected thymocytes to the peripheral lymphoid organs. This differentiation occurs along with cell migration in the context of the thymic microenvironment, formed of epithelial cells, macrophages, dendritic cells, fibroblasts, and extracellular matrix components. Various interactions occurring between microenvironmental cells and differentiating thymocytes are under neuroendocrine control. In this review, we summarize data showing that thymus physiology is pleiotropically influenced by hormones and neuropeptides. These molecules modulate the expression of major histocompatibility complex gene products by microenvironmental cells and the extracellular matrix-mediated interactions, leading to enhanced thymocyte adhesion to thymic epithelial cells. Cytokine production and thymic endocrine function (herein exemplified by thymulin production) are also hormonally controlled, and, interestingly in this latter case, a bidirectional circuitry seems to exist since thymic-derived peptides also modulate hormonal production. In addition to their role in thymic cell proliferation and apoptosis, hormones and neuropeptides also modulate intrathymic T cell differentiation, influencing the generation of the T cell repertoire. Finally, neuroendocrine control of the thymus appears extremely complex, with possible influence of biological circuitry involving the intrathymic production of a variety of hormones and neuropeptides and the expression of their respective receptors by thymic cells.
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Affiliation(s)
- W Savino
- Department of Immunology, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
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