scholarly journals Diabetes and thyroid hormones affect connexin-43 and PKC-ε expression in rat heart atria

2009 ◽  
pp. 211-217 ◽  
Author(s):  
M Mitašíková ◽  
H Lin ◽  
T Soukup ◽  
I Imanaga ◽  
N Tribulová
Keyword(s):  
Connexin 43 ◽  
Electrical Coupling ◽  
Diabetic Rats ◽  
Acute Stage ◽  
Cell Coupling ◽  
Western Blots ◽  
Cx43 Expression ◽  
Acute Diabetes ◽  
Wistar Kyoto ◽  
Heart Atria

We have examined the changes of intercellular electrical coupling protein connexin-43 (Cx43) and of PKC-ε in heart atria of diabetic rats and/or after the treatment with triiodothyronine (T3). Diabetes was induced in Wistar-Kyoto rats by streptozotocin (50 mg/kg, i.v.) and atria were examined after 5 (acute stage) and 10 (chronic stage) weeks. T3 (10 μg/100 g/day) was applied via a gastric tube for the last 10 days prior to the end of the experiments to non-diabetic and to the half of diabetic rats. Expression and phosphorylated status of Cx43, as well as expression of PKC-ε, were analyzed by Western blots using mouse monoclonal anti-Cx43 and rabbit polyclonal anti-PKC-ε antibodies. We found that the Cx43 expression was significantly increased after the treatment with T3 and in the acute diabetes. Both in diabetes and after T3 treatment the phosphorylation of Cx43 isoforms was markedly suppressed compared to the nondiabetic and T3-untreated controls. Such a down-regulation was less pronounced in diabetic rats after the T3-treatment. The expression of atrial PKC-ε was increased in diabetic rats. This increase was suppressed after T3 administration and the expression was decreased in T3-treated non-diabetic rats. We suggest that the reduced Cx43 phosphorylation in diabetic and hyperthyroid rats can deteriorate a cell-to-cell coupling and consequently facilitate a development of atrial tachyarrhythmia in diabetic or hyperthyroid animals.

scholarly journals Opposite Effects of Moderate and Extreme Cx43 Deficiency in Conditional Cx43-Deficient Mice on Angiotensin II-Induced Cardiac Fibrosis

Cells ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1299 ◽  
Author(s):  
Valls-Lacalle ◽  
Negre-Pujol ◽  
Rodríguez ◽  
Varona ◽  
Valera-Cañellas ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
P38 Mapk ◽  
Myocardial Fibrosis ◽  
Connexin 43 ◽  
Cardiac Fibrosis ◽  
Electrical Coupling ◽  
Fibrotic Response ◽  
Cx43 Expression ◽  
Knock Out ◽  
Contrast Normalization

Abstract: Connexin 43 (Cx43) is essential for cardiac electrical coupling, but its effects on myocardial fibrosis is controversial. Here, we analyzed the role of Cx43 in myocardial fibrosis caused by angiotensin II (AngII) using Cx43fl/fl and Cx43Cre-ER(T)/fl inducible knock-out (Cx43 content: 50%) mice treated with vehicle or 4-hydroxytamoxifen (4-OHT) to induce a Cre-ER(T)-mediated global deletion of the Cx43 floxed allele. Myocardial collagen content was enhanced by AngII in all groups (n = 8–10/group, p < 0.05). However, animals with partial Cx43 deficiency (vehicle-treated Cx43Cre-ER(T)/fl) had a significantly higher AngII-induced collagen accumulation that reverted when treated with 4-OHT, which abolished Cx43 expression. The exaggerated fibrotic response to AngII in partially deficient Cx43Cre-ER(T)/fl mice was associated with enhanced p38 MAPK activation and was not evident in Cx43 heterozygous (Cx43+/-) mice. In contrast, normalization of interstitial collagen in 4-OHT-treated Cx43Cre-ER(T)/fl animals correlated with enhanced MMP-9 activity, IL-6 and NOX2 mRNA expression, and macrophage content, and with reduced -SMA and SM22 in isolated fibroblasts. In conclusion, our data demonstrates an exaggerated, p38 MAPK-dependent, fibrotic response to AngII in partially deficient Cx43Cre-ER(T)/fl mice, and a paradoxical normalization of collagen deposition in animals with an almost complete Cx43 ablation, an effect associated with increased MMP-9 activity and inflammatory response and reduced fibroblasts differentiation.

scholarly journals Hindlimb unloading results in increased predisposition to cardiac arrhythmias and alters left ventricular connexin 43 expression

2013 ◽  
Vol 304 (5) ◽  
pp. R362-R373 ◽  
Author(s):  
Julia A. Moffitt ◽  
Matthew K. Henry ◽  
Kathryn C. Welliver ◽  
Amanda J. Jepson ◽  
Emily R. Garnett
Keyword(s):  
Cardiac Arrhythmias ◽  
Connexin 43 ◽  
Electrical Coupling ◽  
Left Ventricular ◽  
Hindlimb Unloading ◽  
Cx43 Expression ◽  
Cardiovascular Deconditioning ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
Sympathovagal Imbalance

Hindlimb unloading (HU) is a well-established animal model of cardiovascular deconditioning. Previous data indicate that HU results in cardiac sympathovagal imbalance. It is well established that cardiac sympathovagal imbalance increases the risk for developing cardiac arrhythmias. The cardiac gap junction protein connexin 43 (Cx43) is predominately expressed in the left ventricle (LV) and ensures efficient cell-to-cell electrical coupling. In the current study we wanted to test the hypothesis that HU would result in increased predisposition to cardiac arrhythmias and alter the expression and/or phosphorylation of LV-Cx43. Electrocardiographic data using implantable telemetry were obtained over a 10- to 14-day HU or casted control (CC) condition and in response to a sympathetic stressor using isoproterenol administration and brief restraint. The arrhythmic burden was calculated using a modified scoring system to quantify spontaneous and provoked arrhythmias. In addition, Western blot analysis was used to measure LV-Cx43 expression in lysates probed with antibodies directed against the total and an unphosphorylated form of Cx43 in CC and HU rats. HU resulted in a significantly greater total arrhythmic burden during the sympathetic stressor with significantly more ventricular arrhythmias occurring. In addition, there was increased expression of total LV-Cx43 observed with no difference in the expression of unphosphorylated LV-Cx43. Specifically, the increased expression of LV-Cx43 was consistent with the phosphorylated form. These data taken together indicate that cardiovascular deconditioning produced through HU results in increased predisposition to cardiac arrhythmias and increased expression of phosphorylated LV-Cx43.

scholarly journals OptoGap: an optogenetics-enabled assay for quantification of cell-cell coupling in multicellular cardiac tissue

2017 ◽  
Author(s):  
Jinzhu Yu ◽  
Patrick M. Boyle ◽  
Aleksandra Klimas ◽  
John C. Williams ◽  
Natalia Trayanova ◽  
...  
Keyword(s):  
Messenger Rna ◽  
Quantitative Methods ◽  
Cardiac Tissue ◽  
De Novo ◽  
Cardiac Fibroblasts ◽  
Direct Method ◽  
Electrical Coupling ◽  
Cell Coupling ◽  
Western Blots ◽  
Cell Cell

AbstractIntercellular electrical coupling is an essential means of communication between cells. It is important to obtain quantitative knowledge of such coupling between cardiomyocytes and nonexcitable cells when, for example, pathological electrical coupling between myofibroblasts and cardiomyocytes yields increased arrhythmia risk or during the integration of donor (e.g. cardiac progenitor) cells with native cardiomyocytes in cell-therapy approaches. Currently, there is no direct method for assessing heterocellular coupling within multicellular tissue. Here we demonstrate experimentally and computationally a new contactless assay for electrical coupling, OptoGap, based on selective illumination of inexcitable cells that express optogenetic actuators and optical sensing of the response of coupled excitable cells, e.g. cardiomyocytes, that are light-insensitive. Cell-cell coupling is quantified by the energy required to elicit an action potential via junctional current from the light-stimulated cell(s). The proposed technique is experimentally validated against the standard indirect approach, GapFRAP, using light-sensitive cardiac fibroblasts and non-transformed cardiomyocytes in a two-dimensional setting. It’s potential applicability to the complex three-dimensional setting of the native heart is corroborated by computational modeling and proper calibration.Intercellular coupling is a fundamental form of communication between cells, essential for the synchronization of physiological processes in different organs. Pathologically altered coupling or the emergence of de novo coupling between native and donor cells are problems of interest in many cardiac applications, e.g. during cell delivery and cell integration for cardiac repair therapy1,2. In particular, interactions between cardiomyocytes and fibroblasts are of interest, especially the pro-arrhythmic increase in coupling as the latter transition to myofibroblasts3-6.Electrical coupling in cardiac tissue is mediated primarily by low-resistance paths formed by gap-junctional proteins (connexins), that can link cardiomyocytes (CMs) to each other and to non-cardiomyocytes (nCMs), such as fibroblasts. Qualitative and quantitative methods, e.g. immunofluorescence, messenger RNA and Western blots, are often used to assay connexin expression levels as a surrogate measure of coupling, but they do not provide functional information. A method for direct quantification of cell-cell coupling within the multicellular tissue context is highly desirable.

Phosphorylation of connexin 43 induced by traumatic brain injury promotes exosome release

2018 ◽  
Vol 119 (1) ◽  
pp. 305-311 ◽  
Author(s):  
Wei Chen ◽  
Yijun Guo ◽  
Wenjin Yang ◽  
Lei Chen ◽  
Dabin Ren ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Gap Junction ◽  
Connexin 43 ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Cx43 Expression ◽  
Term Potentiation ◽  
Junction Protein

Traumatic brain injury (TBI) caused by the external force leads to the neuronal dysfunction and even death. TBI has been reported to significantly increase the phosphorylation of glial gap junction protein connexin 43 (Cx43), which in turn propagates damages into surrounding brain tissues. However, the neuroprotective and anti-apoptosis effects of glia-derived exosomes have also been implicated in recent studies. Therefore, we detected whether TBI-induced phosphorylation of Cx43 would promote exosome release in rat brain. To generate TBI model, adult male Sprague-Dawley rats were subjected to lateral fluid percussion injury. Phosphorylated Cx43 protein levels and exosome activities were quantified using Western blot analysis following TBI. Long-term potentiation (LTP) was also tested in rat hippocampal slices. TBI significantly increased the phosphorylated Cx43 and exosome markers expression in rat ipsilateral hippocampus, but not cortex. Blocking the activity of Cx43 or ERK, but not JNK, significantly suppressed TBI-induced exosome release in hippocampus. Furthermore, TBI significantly inhibited the induction of LTP in hippocampal slices, which could be partially but significantly restored by pretreatment with exosomes. The results imply that TBI-activated Cx43 could mediate a nociceptive effect by propagating the brain damages, as well as a neuroprotective effect by promoting exosome release. NEW & NOTEWORTHY We have demonstrated in rat traumatic brain injury (TBI) models that both phosphorylated connexin 43 (p-Cx43) expression and exosome release were elevated in the hippocampus following TBI. The promoted exosome release depends on the phosphorylation of Cx43 and requires ERK signaling activation. Exosome treatment could partially restore the attenuated long-term potentiation. Our results provide new insight for future therapeutic direction on the functional recovery of TBI by promoting p-Cx43-dependent exosome release but limiting the gap junction-mediated bystander effect.

Abstract 336: A 14-3-3 Mode-1 Binding Motif Promotes Gap Junction Internalization During Acute Cardiac Ischemia

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
James W Smyth ◽  
Jose M Sanchez ◽  
Samy Lamouille ◽  
Ting-Ting Hong ◽  
Jacob M Vogan ◽  
...  
Keyword(s):  
Gap Junction ◽  
Protein Trafficking ◽  
Connexin 43 ◽  
Electrical Coupling ◽  
Acute Ischemia ◽  
Binding Motif ◽  
Wild Type ◽  
Gap Junction Coupling ◽  
Junction Coupling ◽  
Cell Cell

During each heartbeat, robust cell-cell electrical coupling via connexin 43 (Cx43) gap junctions allows billions of individual cardiomyocytes to contract in synchrony. Cx43 turns over rapidly, and altered Cx43 trafficking during disease contributes to the arrhythmias of sudden cardiac death. The overall phosphorylation status of the Cx43 protein is known to regulate gap junction coupling, but the role of many residue specific phosphorylation events remains unknown. One such residue, Ser373, forms a mode-1 14-3-3 binding motif upon phosphorylation. Given that 14-3-3 proteins are known to regulate protein trafficking, we hypothesized a role for Cx43 Ser373 phosphorylation in regulation of Cx43 gap junction coupling. Using Langendorff-perfused mouse hearts we find robust phosphorylation of Cx43 at Ser373 and Ser368 after 30 min of no-flow ischemia. In human cell lines, a S373A mutation ablated Cx43/14-3-3 complexing and 35 S pulse-chase revealed Cx43 S373A also experiences a longer half-life than wild-type Cx43. Previous reports have implicated phosphorylation of Cx43 Ser368 in PKC mediated Cx43 internalization. We find that upon activation of PKC, the Cx43 S373A mutant undergoes lower and more transient levels of phosphorylation at Ser368 than wild-type Cx43. Consistent with these data, siRNA-mediated ablation of 14-3-3 expression results in enlargement of gap junction plaque formation at cell-cell borders. In conclusion, we propose that phosphorylation of Cx43 Ser373 results in 14-3-3 binding which promotes and maintains phosphorylation of Cx43 Ser368 and the subsequent internalization of gap junction channels. These results identify for the first time a specific role for 14-3-3 proteins in regulation of Cx43 internalization during acute ischemia and contribute to the development of therapies aimed at preserving or enhancing gap junction coupling in the heart.

Antioxidant, anti-inflammatory, and anti-apoptotic effects of zinc supplementation in testes of rats with experimentally induced diabetes

2018 ◽  
Vol 43 (10) ◽  
pp. 1010-1018 ◽  
Author(s):  
Neven M. Aziz ◽  
Maha Y. Kamel ◽  
Manar S. Mohamed ◽  
Sabreen M. Ahmed
Keyword(s):  
Connexin 43 ◽  
Concomitant Administration ◽  
Serum Levels ◽  
Diabetic Rats ◽  
Control Group ◽  
Albino Rats ◽  
Safe Alternative ◽  
Once Daily ◽  
Factor Α ◽  
Percent Area

One of the major obstacles that males with diabetes may confront is subfertility or infertility. Thus, the present study investigated the effect of co-administration of metformin and zinc (Zn) on the testes of streptozotocin-induced diabetic rats. Male albino rats were randomly divided into 4 groups: control group; untreated diabetic group; diabetic + metformin group, in which diabetic rats were treated orally with metformin (250 mg/kg) once daily for 4 weeks; and diabetic + metformin + Zn group, in which diabetic rats were treated orally with metformin in combination with Zn (10 mg/kg) once daily for 4 weeks. Concomitant administration of metformin and Zn produced a significant decrease in serum levels of glucose and insulin and testicular levels of malondialdehyde and tumor necrosis factor α. Additionally, there was a significant increase in serum levels of Zn, testosterone, and follicle-stimulating hormone, as well as testicular total antioxidant capacity and anti-apoptotic protein Bcl-2, when compared with both the diabetic and metformin-treated diabetic groups. Moreover, co-administration of Zn and metformin significantly improved testicular histopathology, with a significant reduction in percent area of collagen fibers and nuclear factor kappa B (p65) immunoreactivity and a significant increase in seminiferous tubule diameter and connexin 43 immunoreactivity as compared with the diabetic and metformin-treated diabetic groups. In conclusion, the combination of Zn and metformin was an efficacious and safe alternative treatment, as it had superior antihyperglycemic efficacy and provided additional benefits over metformin alone in rats with type 2 diabetes.

Effects of ferulic acid on oxidative stress, heat shock protein 70, connexin 43, and monoamines in the hippocampus of pentylenetetrazole-kindled rats

2017 ◽  
Vol 95 (6) ◽  
pp. 732-742 ◽  
Author(s):  
Abdelaziz M. Hussein ◽  
Khaled M. Abbas ◽  
Osama A. Abulseoud ◽  
El-Hussainy M.A. El-Hussainy
Keyword(s):  
Oxidative Stress ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Ferulic Acid ◽  
Group Treatment ◽  
Heat Shock Protein 70 ◽  
Connexin 43 ◽  
Hsp70 Expression ◽  
Neuroprotective Effects ◽  
Cx43 Expression

The present study investigated the effects of ferulic acid (FA) on pentylenetetrazole (PTZ)-induced seizures, oxidative stress markers (malondialdehyde (MDA), catalase, and reduced glutathione (GSH)), connexin (Cx) 43, heat shock protein 70 (Hsp 70), and monoamines (serotonin (5-HT) and norepinephrine (NE)) levels in a rat model of PTZ-induced kindling. Sixty Sprague Dawley rats were divided into 5 equal groups: (a) normal group; (b) FA group: normal rats received FA at a dose of 40 mg/kg daily; (c) PTZ group: normal rats received PTZ at a dose of 50 mg/kg i.p. on alternate days for 15 days; (d) FA-before group: treatment was the same as for the PTZ group, except rats received FA; and (e) FA-after group: rats received FA from sixth dose of PTZ. PTZ caused a significant increase in MDA, Cx43, and Hsp70 along with a significant decrease in GSH, 5-HT, and NE levels and CAT activity in the hippocampus (p < 0.05). Pre- and post-treatment with FA caused significant improvement in behavioral parameters, MDA, CAT, GSH, 5-HT, NE, Cx43 expression, and Hsp70 expression in the hippocampal region (p < 0.05). We conclude that FA has neuroprotective effects in PTZ-induced epilepsy, which might be due to attenuation of oxidative stress and Cx43 expression and upregulation of neuroprotective Hsp70 and neurotransmitters (5-HT and NE).

scholarly journals The modulatory effects of connexin 43 on cell death/survival beyond cell coupling

2007 ◽  
Vol 94 (1-2) ◽  
pp. 219-232 ◽  
Author(s):  
A RODRIGUEZSINOVAS ◽  
A CABESTRERO ◽  
D LOPEZ ◽  
I TORRE ◽  
M MORENTE ◽  
...  
Keyword(s):  
Cell Death ◽  
Connexin 43 ◽  
Cell Coupling

scholarly journals Transforming growth factor-β1 up-regulates connexin43 expression in osteocytes via canonical Smad-dependent signaling pathway

2018 ◽  
Vol 38 (6) ◽  
Author(s):  
Wenjing Liu ◽  
Yujia Cui ◽  
Jianxun Sun ◽  
Linyi Cai ◽  
Jing Xie ◽  
...  
Keyword(s):  
Growth Factor ◽  
Connexin 43 ◽  
Transforming Growth Factor ◽  
Bone Cells ◽  
Underlying Mechanism ◽  
Transforming Growth Factor Β1 ◽  
Type I ◽  
Gap Junctional Intercellular Communication ◽  
Cx43 Expression ◽  
Tgf Β1

Connexin 43 (Cx43)-mediated gap junctional intercellular communication (GJIC) has been shown to be important in regulating multiple functions of bone cells. Transforming growth factor-β1 (TGF-β1) exhibited controversial effects on the expression of Cx43 in different cell types. To date, the effect of TGF-β1 on the Cx43 expression of osteocytes is still unknown. In the present study, we detected the expression of TGF-β1 in osteocytes and bone tissue, and then used recombinant mouse TGF-β1 to elucidate its effect on gap junctions (GJs) of osteocytes. Our data indicated that TGF-β1 up-regulated both mRNA and protein expression of Cx43 in osteocytes. Together with down-regulation of Cx43 expression after being treated with TGF-β type I receptor inhibitor Repsox, we deduced that TGF-β1 can positively regulate Cx43 expression in osteocytes. Thus we next focussed on the downstream signals of TGF-β and found that TGF-β1-mediated smads, Smad3 and Smad4, to translocate into nucleus. These translocated signal proteins bind to the promoter of Gja1 which was responsible for the changed expression of Cx43. The present study provides evidence that TGF-β1 can enhance GJIC between osteocytes through up-regulating Cx43 expression and the underlying mechanism involved in the activation of Smad-dependent pathway.

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