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.

Abstract 76: Effects of Long-term Angiotensin-II Infusion on Cardiac and Renal Fibrosis are Blunted in TNFR1-deficient Mice

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Magdalena Mayr ◽  
Clemens Duerrschmid ◽  
Dorellyn B Lee ◽  
Guillermo Medrano ◽  
George E Taffet ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Systolic Blood Pressure ◽  
Renal Fibrosis ◽  
Cardiac Fibrosis ◽  
Ang Ii ◽  
Fibrotic Response ◽  
2D Echocardiography ◽  
Collagen Iii

Background: Brief systemic infusion of Angiotensin-II (Ang-II) to wild-type (WT) mice initiates the development of cardiac interstitial fibrosis. Genetic deletion of tumor necrosis factor receptor 1 (TNFR1) obviates this development and concurrently inhibits Ang-II-induced cardiac remodeling and dysfunction. We now investigated long-term effects of Ang-II on the heart, kidney, and cardiorenal function. Methods: WT and TNFR1-KO mice were infused with 1.5 ug/kg/min Ang-II for 1 and 6 weeks (no uninephrectomy or high-salt diet). Heart, kidney, and serum were isolated and evaluated by histology, cytometry, qPCR, and ELISA techniques. Cardiac function was determined by 2D-echocardiography, systolic blood pressure by tail-cuff plethysmography. Results: Brief infusion of Ang-II to WT mice did not evoke a fibrotic response in the kidney. However, after 6 weeks, WT kidneys developed minimal, but significant interstitial collagen deposition which was supported by upregulation of collagen-I, collagen-III, and alpha-smooth muscle actin gene activation. This fibrotic development was associated with the appearance of myeloid fibroblast precursors, pro-inflammatory M1 and pro-fibrotic M2 cells, and myofibroblasts. Transcriptional expression of pro-inflammatory and pro-fibrotic genes was also increased. These changes were not seen in Ang-II-infused TNFR1-KO kidneys. In WT hearts, despite the disappearance of myeloid cells, cardiac fibrosis persisted throughout the 6-week infusion. WT hearts developed clear evidence of accelerated cardiac hypertrophy and remodeling associated with impaired systolic function. Again, these changes were not seen in Ang-II-infused TNFR1-KO hearts. By contrast, both WT and TNFR1-KO mice responded identically with similar elevations of systolic blood pressure, and serum blood urea nitrogen and creatinine levels. Conclusions: Ang-II-infusion induced an immediate fibrotic response in the heart while fibrosis in the kidney developed slowly. The cardiac fibrosis was accompanied by progressive adverse remodeling and worsening of function over time. TNFR1-KO mice were protected from the Ang-II-induced cardiac and renal fibrosis, despite similar increases in blood pressure and renal dysfunction.

scholarly journals Apelin-13 Regulates Angiotensin II-Induced Cx43 Downregulation and Autophagy via the AMPK/mTOR Signaling Pathway in HL-1 Cells

2020 ◽  
pp. 813-822
Author(s):  
Y CHEN ◽  
X QIAO ◽  
L ZHANG ◽  
X LI ◽  
Q LIU
Keyword(s):  
Atrial Fibrillation ◽  
Angiotensin Ii ◽  
Signaling Pathway ◽  
Connexin 43 ◽  
Mtor Signaling ◽  
Atrial Remodeling ◽  
Mtor Signaling Pathway ◽  
Cx43 Expression ◽  
Compound C ◽  
Cell Hypertrophy

Atrial fibrillation is associated with atrial remodeling, in which connexin 43 (Cx43) and cell hypertrophy play important roles. In this study, apelin-13, an aliphatic peptide, was used to explore the protective effects of the adenosine monophosphate-activated protein kinase (AMPK)/mTOR signaling pathway on Cx43 expression and autophagy, using murine atrial HL-1 cells. The expression of Cx43, AMPK, B-type natriuretic peptide (BNP) and pathway-related proteins was detected by Western blot analysis. Cellular fluorescence imaging was used to visualize Cx43 distribution and the cytoskeleton. Our results showed that the Cx43 expression was significantly decreased in HL-1 cells treated with angiotensin II but increased in cells additionally treated with apelin-13. Meanwhile, apelin-13 decreased BNP expression and increased AMPK expression. However, the expression of Cx43 and LC3 increased by apelin-13 was inhibited by treatment with compound C, an AMPK inhibitor. In addition, rapamycin, an mTOR inhibitor, promoted the development of autophagy, further inhibited the protective effect on Cx43 expression and increased cell hypertrophy. Thus, apelin-13 enhances Cx43 expression and autophagy via the AMPK/mTOR signaling pathway, and serving as a potential therapeutic target for atrial fibrillation.

Effect of angiotensin II and ethanol on the expression of connexin 43 in WB rat liver epithelial cells

2001 ◽  
Vol 357 (3) ◽  
pp. 769-777 ◽  
Author(s):  
Shaila BOKKALA ◽  
Helena M. REIS ◽  
Emanuel RUBIN ◽  
Suresh K. JOSEPH
Keyword(s):  
Angiotensin Ii ◽  
Epithelial Cells ◽  
Rat Liver ◽  
Connexin 43 ◽  
Ang Ii ◽  
Cx43 Expression ◽  
Gap Junctional Communication ◽  
Junctional Communication ◽  
Rat Liver Epithelial Cells ◽  
Gap Junctional

The turnover of connexin 43 (Cx43) is very rapid in many cells and involves both the lysosomal and proteasomal protease pathways. Here we show that Ca2+-mobilizing agonists such as angiotensin II (Ang II) can up-regulate the expression of Cx43 in WB rat liver epithelial cells. Vasopressin had the same effect in A7R5 smooth-muscle cells. The effect of Ang II was not prevented by pretreatment with proteasomal or lysosomal inhibitors and was associated with an enhanced biosynthesis of Cx43 as measured by metabolic labelling experiments. The accumulation of Cx43 occurred in intracellular compartments and at the cell surface, as determined by confocal immunofluorescence studies and by immunoblotting of fractions soluble and insoluble in Triton X-100. Chronic treatment of WB cells with ethanol inhibited Cx43 expression; this was associated with decreased biosynthesis of Cx43. Neither treatment with Ang II nor treatment with ethanol altered the levels of Cx43 mRNA. Incubation of WB cells with Ang II did not alter gap-junctional communication as judged by a dye-coupling assay. However, treatment with ethanol markedly decreased gap-junctional communication and this effect was diminished in Ang-II-treated cells, demonstrating that gap-junctional communication is linked to the level of Cx43 expression. We conclude that Cx43 biosynthesis is regulated by Ca2+-mobilizing agonists and ethanol in WB cells. The changes in Cx43 expression might have a role in modifying the conduction of metabolites and second messengers between cells.

scholarly journals AMPKα1 deletion in myofibroblasts exacerbates post-myocardial infarction fibrosis by a connexin 43 mechanism

2021 ◽  
Vol 116 (1) ◽  
Author(s):  
Cécile Dufeys ◽  
Evangelos-Panagiotis Daskalopoulos ◽  
Diego Castanares-Zapatero ◽  
Simon J. Conway ◽  
Audrey Ginion ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Connexin 43 ◽  
Molecular Mechanisms ◽  
Cardiac Fibrosis ◽  
Left Ventricular ◽  
Conditional Knockout ◽  
Fibroblast Proliferation ◽  
Cx43 Expression ◽  
Amp Activated Protein Kinase ◽  
Specific Deletion

AbstractWe have previously demonstrated that systemic AMP-activated protein kinase α1 (AMPKα1) invalidation enhanced adverse LV remodelling by increasing fibroblast proliferation, while myodifferentiation and scar maturation were impaired. We thus hypothesised that fibroblastic AMPKα1 was a key signalling element in regulating fibrosis in the infarcted myocardium and an attractive target for therapeutic intervention. The present study investigates the effects of myofibroblast (MF)-specific deletion of AMPKα1 on left ventricular (LV) adaptation following myocardial infarction (MI), and the underlying molecular mechanisms. MF-restricted AMPKα1 conditional knockout (cKO) mice were subjected to permanent ligation of the left anterior descending coronary artery. cKO hearts exhibit exacerbated post-MI adverse LV remodelling and are characterised by exaggerated fibrotic response, compared to wild-type (WT) hearts. Cardiac fibroblast proliferation and MF content significantly increase in cKO infarcted hearts, coincident with a significant reduction of connexin 43 (Cx43) expression in MFs. Mechanistically, AMPKα1 influences Cx43 expression by both a transcriptional and a post-transcriptional mechanism involving miR-125b-5p. Collectively, our data demonstrate that MF-AMPKα1 functions as a master regulator of cardiac fibrosis and remodelling and might constitute a novel potential target for pharmacological anti-fibrotic applications.

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 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 Cdon deficiency causes cardiac remodeling through hyperactivation of WNT/β-catenin signaling

2017 ◽  
Vol 114 (8) ◽  
pp. E1345-E1354 ◽  
Author(s):  
Myong-Ho Jeong ◽  
Hyun-Ji Kim ◽  
Jung-Hoon Pyun ◽  
Kyu-Sil Choi ◽  
Dong I. Lee ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Gap Junction ◽  
Cardiac Remodeling ◽  
Connexin 43 ◽  
Cardiac Fibrosis ◽  
Critical Role ◽  
Cell Surface Receptor ◽  
Cx43 Expression ◽  
Rat Cardiomyocytes ◽  
Junction Protein

On pathological stress, Wnt signaling is reactivated and induces genes associated with cardiac remodeling and fibrosis. We have previously shown that a cell surface receptor Cdon (cell-adhesion associated, oncogene regulated) suppresses Wnt signaling to promote neuronal differentiation however its role in heart is unknown. Here, we demonstrate a critical role of Cdon in cardiac function and remodeling. Cdon is expressed and predominantly localized at intercalated disk in both mouse and human hearts. Cdon-deficient mice develop cardiac dysfunction including reduced ejection fraction and ECG abnormalities.Cdon−/−hearts exhibit increased fibrosis and up-regulation of genes associated with cardiac remodeling and fibrosis. Electrical remodeling was demonstrated by up-regulation and mislocalization of the gap junction protein, Connexin 43 (Cx43) inCdon−/−hearts. In agreement with altered Cx43 expression, functional analysis both usingCdon−/−cardiomyocytes and shRNA-mediated knockdown in rat cardiomyocytes shows aberrant gap junction activities. Analysis of the underlying mechanism reveals thatCdon−/−hearts exhibit hyperactive Wnt signaling as evident by β-catenin accumulation and Axin2 up-regulation. On the other hand, the treatment of rat cardiomyocytes with a Wnt activator TWS119 reduces Cdon levels and aberrant Cx43 activities, similarly to Cdon-deficient cardiomyocytes, suggesting a negative feedback between Cdon and Wnt signaling. Finally, inhibition of Wnt/β-catenin signaling by XAV939, IWP2 or dickkopf (DKK)1 prevented Cdon depletion-induced up-regulation of collagen 1a and Cx43. Taken together, these results demonstrate that Cdon deficiency causes hyperactive Wnt signaling leading to aberrant intercellular coupling and cardiac fibrosis. Cdon exhibits great potential as a target for the treatment of cardiac fibrosis and cardiomyopathy.

scholarly journals FAM114A1 Influences Cardiac Fibrosis by Regulating Angiotensin II Signaling in Cardiac Fibroblasts

2021 ◽  
Author(s):  
Kadiam C Venkata Subbaiah ◽  
Jiangbin Wu ◽  
Wai Hong Wilson Tang ◽  
Peng Yao
Keyword(s):  
Heart Failure ◽  
Angiotensin Ii ◽  
Cardiac Fibrosis ◽  
Cardiac Fibroblasts ◽  
Sequence Similarity ◽  
Ang Ii ◽  
Fibrotic Response ◽  
Genetic Ablation ◽  
Angiotensin Ii Signaling ◽  
Human And Mouse

AbstractCardiac fibrosis, a primary contributor to heart failure (HF) and sudden death, is considered as an important target for HF therapy. However, the signaling pathways that govern cardiac fibroblast (CF) function during cardiac fibrosis have not been fully elucidated. Here, we found that a functionally unannotated human myocardial infarction (MI) associated gene, family with sequence similarity 114 member A1 (FAM114A1), is induced in failing human and mouse hearts compared to non-failing hearts. Homozygous knockout of Fam114a1 (Fam114a1−/−) in the mouse genome reduces cardiac hypertrophy and fibrosis while significantly restores cardiac function in angiotensin (Ang) II- and MI-induced HF mouse models. Fam114a1 deletion antagonizes Ang II induced inflammation and oxidative stress. Using isolated mouse primary CFs in wild type and Fam114a1−/− mice, we found that FAM114A1 is a critical autonomous factor for CF proliferation, activation, and migration. We discovered that FAM114A1 interacts with angiotensin receptor associated protein (AGTRAP) and regulates the expression of angiotensin type 1 receptor (AT1R) and downstream Ang II signaling transduction, and subsequently influences pro-fibrotic response. Using RNA-Seq in mouse primary CFs, we identified differentially expressed genes including extracellular matrix proteins such as Adamts15. RNAi-mediated inactivation of Adamts15 attenuates CF activation and collagen deposition. Our results indicate that FAM114A1 regulates Ang II signaling and downstream pro-fibrotic and pro-inflammatory gene expression, thereby activating cardiac fibroblasts and augmenting pathological cardiac remodeling. These findings provide novel insights into regulation of cardiac fibrosis and identify FAM114A1 as a new therapeutic target for treatment of cardiac disease.SignificanceCardiac fibrosis is a hallmark of heart failure and angiotensin II signaling promotes pro-fibrotic response in the heart. This study is a pioneering investigation of the role of a functionally unknown protein FAM114A1. We show that FAM114A1 expression is induced in human and mouse failing hearts. Genetic ablation of FAM114A1 can effectively reduce cardiac fibrosis and pathological remodeling. Isolated cardiac fibroblasts from Fam114a1 knockout mice show reduced response to Ang II stimulation and compromised myofibroblast activation. Mechanistically, FAM114A1 binds to AGTRAP and influences AT1R protein expression, thereby enhancing angiotensin II signaling and pro-fibrotic response. Thus, FAM114A1 is a novel factor that modulates cardiac fibrosis and pharmacological inhibition of FAM114A1 may be a therapeutic strategy for the treatment of heart disease.

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.

Sign in / Sign up

Export Citation Format

Share Document