scholarly journals High-Glucose-Induced Rab20 Upregulation Disrupts Gap Junction Intercellular Communication and Promotes Apoptosis in Retinal Endothelial and Müller Cells: Implications for Diabetic Retinopathy

2020 ◽  
Vol 9 (11) ◽  
pp. 3710
Author(s):  
Dongjoon Kim ◽  
Casey Stottrup Lewis ◽  
Vijay P. Sarthy ◽  
Sayon Roy
Keyword(s):  
Diabetic Retinopathy ◽  
Gap Junction ◽  
Intercellular Communication ◽  
High Glucose ◽  
Connexin 43 ◽  
Müller Cells ◽  
Muller Cells ◽  
Dye Transfer ◽  
Cx43 Expression ◽  
Gap Junction Intercellular Communication

To investigate whether high glucose (HG) alters Rab20 expression and compromises gap junction intercellular communication (GJIC) and cell survival, retinal cells were studied for altered intracellular trafficking of connexin 43 (Cx43). Retinal endothelial cells (RRECs) and retinal Müller cells (rMCs) were grown in normal (N; 5 mM glucose) or HG (30 mM glucose) medium for seven days. In parallel, cells grown in HG medium were transfected with either Rab20 siRNA or scrambled siRNA as a control. Rab20 and Cx43 expression and their localization and distribution were assessed using Western Blot and immunostaining, respectively. Changes in GJIC activity were assessed using scrape load dye transfer, and apoptosis was identified using differential dye staining assay. In RRECs or rMCs grown in HG medium, Rab20 expression was significantly increased concomitant with a decreased number of Cx43 plaques. Importantly, a significant increase in the number of Cx43 plaques and GJIC activity was observed in cells transfected with Rab20 siRNA. Additionally, Rab20 downregulation inhibited HG-induced apoptosis in RRECs and rMCs. Results indicate HG-mediated Rab20 upregulation decreases Cx43 localization at the cell surface, resulting in compromised GJIC activity. Reducing Rab20 expression could be a useful strategy in preventing HG-induced vascular and Müller cell death associated with diabetic retinopathy.

Human Marrow Stromal Cells Enhance Connexin43 Gap Junction Intercellular Communication in Cultured Astrocytes

2005 ◽  
Vol 14 (2-3) ◽  
pp. 109-117 ◽  
Author(s):  
Qi Gao ◽  
Mark Katakowski ◽  
Xiaoguang Chen ◽  
Yi Li ◽  
Michael Chopp
Keyword(s):  
Gap Junction ◽  
Intercellular Communication ◽  
Stromal Cells ◽  
Connexin 43 ◽  
Marrow Stromal Cells ◽  
Dye Transfer ◽  
Cx43 Expression ◽  
Soluble Factors ◽  
Functional Benefit ◽  
Gap Junction Intercellular Communication

Human marrow stromal cells (hMSCs) provide functional benefit in rats subjected to stroke. Astrocytes are coupled into a cellular network via gap junction channels, predominantly composed of connexin-43 (Cx43) proteins. Astrocytes are believed to play a vital role in neuroprotection by providing energy substrates to neurons and by regulating the concentrations of K+ and neurotransmitters via gap junctions. We therefore investigated the effect of factors secreted by hMSCs on gap junction intercellular communication (GJIC), expression of Cx43, and phosphorylation of Cx43 in an astrocyte cell culture system. Exposing rat cortical astrocytes to various concentrations of hMSC conditioned medium, we demonstrate that hMSCs produce soluble factors that significantly increase astrocytic GJIC, measured by the scrape-loading dye transfer method. Immunohistochemistry and Western blot showed increased Cx43 expression concomitant with altered GJIC. As the PI3K/Akt signaling pathway has been demonstrated to alter gap junction expression and GJIC, we selectively blocked phosphoinositide 3-kinase (PI3K). Addition of the PI3K inhibitor LY294002 decreased GJIC and Cx43 expression in astrocytes. These inhibitory effects of LY294002 were countered by the addition of hMSC conditioned media. Furthermore, coculturing hMSCs with rat astrocytes increased astrocyte GJIC in a manner dependent upon the hMSC/astrocyte ratio. These findings demonstrate that hMSCs secrete soluble factors that increase GJIC of astrocytes through upregulation of Cx43, and indicate a mechanistic role for PI3K.

scholarly journals Mesenchymal marker expression is elevated in Müller cells exposed to high glucose and in animal models of diabetic retinopathy

Oncotarget ◽  
2016 ◽  
Vol 8 (3) ◽  
pp. 4582-4594 ◽  
Author(s):  
Ti Zhou ◽  
Di Che ◽  
Yuqing Lan ◽  
Zhenzhen Fang ◽  
Jinye Xie ◽  
...  
Keyword(s):  
Diabetic Retinopathy ◽  
Animal Models ◽  
High Glucose ◽  
Müller Cells ◽  
Muller Cells ◽  
Mesenchymal Marker ◽  
Marker Expression

scholarly journals High Glucose Induces Mitochondrial Dysfunction in Retinal Müller Cells: Implications for Diabetic Retinopathy

2017 ◽  
Vol 58 (7) ◽  
pp. 2915 ◽  
Author(s):  
Thomas Tien ◽  
Joyce Zhang ◽  
Tetsuya Muto ◽  
Dongjoon Kim ◽  
Vijay P. Sarthy ◽  
...  
Keyword(s):  
Diabetic Retinopathy ◽  
Mitochondrial Dysfunction ◽  
High Glucose ◽  
Müller Cells ◽  
Muller Cells

scholarly journals Gap Junction Intercellular Communication Mediated by Connexin43 in Astrocytes Is Essential for Their Resistance to Oxidative Stress

2013 ◽  
Vol 289 (3) ◽  
pp. 1345-1354 ◽  
Author(s):  
Hoa T. Le ◽  
Wun Chey Sin ◽  
Shannon Lozinsky ◽  
John Bechberger ◽  
José Luis Vega ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Protective Effect ◽  
Gap Junction ◽  
Intercellular Communication ◽  
Cx43 Expression ◽  
Knock Out ◽  
Gap Junction Intercellular Communication ◽  
Junction Protein ◽  
A Cell ◽  
Hypoxia Reoxygenation

Oxidative stress induced by reactive oxygen species (ROS) is associated with various neurological disorders including aging, neurodegenerative diseases, as well as traumatic and ischemic insults. Astrocytes have an important role in the anti-oxidative defense in the brain. The gap junction protein connexin43 (Cx43) forms intercellular channels as well as hemichannels in astrocytes. In the present study, we investigated the contribution of Cx43 to astrocytic death induced by the ROS hydrogen peroxide (H2O2) and the mechanism by which Cx43 exerts its effects. Lack of Cx43 expression or blockage of Cx43 channels resulted in increased ROS-induced astrocytic death, supporting a cell protective effect of functional Cx43 channels. H2O2 transiently increased hemichannel activity, but reduced gap junction intercellular communication (GJIC). GJIC in wild-type astrocytes recovered after 7 h, but was absent in Cx43 knock-out astrocytes. Blockage of Cx43 hemichannels incompletely inhibited H2O2-induced hemichannel activity, indicating the presence of other hemichannel proteins. Panx1, which is predicted to be a major hemichannel contributor in astrocytes, did not appear to have any cell protective effect from H2O2 insults. Our data suggest that GJIC is important for Cx43-mediated ROS resistance. In contrast to hypoxia/reoxygenation, H2O2 treatment decreased the ratio of the hypophosphorylated isoform to total Cx43 level. Cx43 has been reported to promote astrocytic death induced by hypoxia/reoxygenation. We therefore speculate the increase in Cx43 dephosphorylation may account for the facilitation of astrocytic death. Our findings suggest that the role of Cx43 in response to cellular stress is dependent on the activation of signaling pathways leading to alteration of Cx43 phosphorylation states.

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