Abstract 28: In Vivo Knockdown of Mirna-15b Results in Increased Cardiac Hypertrophy and Fibrosis in Response to Pressure Overload of the Mouse Heart

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Anke J Tijsen ◽  
Ingeborg van der Made ◽  
Elza D van Deel ◽  
Monika Hiller ◽  
Yolan J Reckman ◽  
...  

MiRNAs play an important role in the control of diverse aspects of cardiac function. MiR-15b is highly expressed in the heart and is found consistently upregulated in hypertrophic and failing hearts. To investigate the function of miR-15b in the heart we set out two experiments. In the first experiment we generated two independent transgenic mouse lines that drive miR-15b expression under the αMHC-promotor and show a three and four fold overexpression of miR-15b. Strikingly, both lines show a decrease in heart weight/tibia length of 20% in adult and aged mice when compared to littermate controls. We investigated the response of these transgenic mice to thoracic aorta constriction (TAC) and found no differences in the hypertrophic response or in cardiac function measured by echocardiography between wild-type and transgenic mice. In a second experiment, we inhibited miR-15b using LNA-based antimiRs. In these mice, TAC resulted in an increased hypertrophic response and increased cardiac fibrosis when compared to a negative control antimiR. A wide range of predicted targets of miR-15 belong to the pathways of the TGFβ-superfamily and using a smad-dependent reporter we show that miR-15b inhibits TGFβ-induced Smad activity in HepG2 cells. One of the predicted targets in the TGFβ pathway is TGFβ receptor 1 (TGFβR1), of which the 3’UTR contains six predicted miR-15 binding sites. This suggests that the phenotype in the transgenic mice and after knockdown of miR-15b may be (partly) mediated by repression of TGFβR1. Indeed, in the adult miR-15b transgenic hearts we found a downregulation of TGFβR1 mRNA and protein and we confirmed binding of miR-15 to the TGFβR1 3’UTR by luciferase assays. In conclusion, miR-15b causes a cardiac hypotrophic phenotype at baseline in transgenic mice and inhibition of miR-15b leads to a stronger hypertrophic and fibrotic response after TAC. Furthermore miR-15b inhibits the TGFβ pathway by targeting the TGFβR1 and possibly other targets in this pathway. This research is funded by the Dutch Heart Foundation (NHF grant #2007B077).

2008 ◽  
Vol 294 (6) ◽  
pp. H2889-H2897 ◽  
Author(s):  
Qianwen Wang ◽  
Rajakumar V. Donthi ◽  
Jianxun Wang ◽  
Alex J. Lange ◽  
Lewis J. Watson ◽  
...  

During ischemia and heart failure, there is an increase in cardiac glycolysis. To understand if this is beneficial or detrimental to the heart, we chronically elevated glycolysis by cardiac-specific overexpression of phosphatase-deficient 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2) in transgenic mice. PFK-2 controls the level of fructose-2,6-bisphosphate (Fru-2,6-P2), an important regulator of phosphofructokinase and glycolysis. Transgenic mice had over a threefold elevation in levels of Fru-2,6-P2. Cardiac metabolites upstream of phosphofructokinase were significantly reduced, as would be expected by the activation of phosphofructokinase. In perfused hearts, the transgene caused a significant increase in glycolysis that was less sensitive to inhibition by palmitate. Conversely, oxidation of palmitate was reduced by close to 50%. The elevation in glycolysis made isolated cardiomyocytes highly resistant to contractile inhibition by hypoxia, but in vivo the transgene had no effect on ischemia-reperfusion injury. Transgenic hearts exhibited pathology: the heart weight-to-body weight ratio was increased 17%, cardiomyocyte length was greater, and cardiac fibrosis was increased. However, the transgene did not change insulin sensitivity. These results show that the elevation in glycolysis provides acute benefits against hypoxia, but the chronic increase in glycolysis or reduction in fatty acid oxidation interferes with normal cardiac metabolism, which may be detrimental to the heart.


2021 ◽  
Vol 11 ◽  
Author(s):  
Paula Bollmann ◽  
Franziska Werner ◽  
Marko Jaron ◽  
Tom A. Bruns ◽  
Hartmut Wache ◽  
...  

As part of our ongoing studies on the potential pathophysiological role of serine/threonine phosphatases (PP) in the mammalian heart, we have generated mice with cardiac-specific overexpression of PP2Cβ (PP2C-TG) and compared them with littermate wild type mice (WT) serving as a control. Cardiac fibrosis was noted histologically in PP2C-TG. Collagen 1a, interleukin-6 and the natriuretic peptides ANP and BNP were augmented in PP2C-TG vs. WT (p < 0.05). Left atrial preparations from PP2C-TG were less resistant to hypoxia than atria from WT. PP2C-TG maintained cardiac function after the injection of lipopolysaccharide (LPS, a model of sepsis) and chronic isoproterenol treatment (a model of heart failure) better than WT. Crossbreeding of PP2C-TG mice with PP2A-TG mice (a genetic model of heart failure) resulted in double transgenic (DT) mice that exhibited a pronounced increase of heart weight in contrast to the mild hypertrophy noted in the mono-transgenic mice. The ejection fraction was reduced in PP2C-TG and in PP2A-TG mice compared with WT, but the reduction was the highest in DT compared with WT. PP2A enzyme activity was enhanced in PP2A-TG and DT mice compared with WT and PP2C-TG mice. In summary, cardiac overexpression of PP2Cβ and co-overexpression of both the catalytic subunit of PP2A and PP2Cβ were detrimental to cardiac function. PP2Cβ overexpression made cardiac preparations less resistant to hypoxia than WT, leading to fibrosis, but PP2Cβ overexpression led to better adaptation to some stressors, such as LPS or chronic β-adrenergic stimulation. Hence, the effect of PP2Cβ is context sensitive.


2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Fuli Xiang ◽  
Min Fang ◽  
Katherine Yutzey

Background: Cardiac fibrosis increases myocardium stiffness, impairs cardiac function and contributes to heart failure. Activated fibroblasts produce excessive extracellular matrix leading to fibrosis and impaired cardiac function. Pathologically activated canonical Wnt signaling has been implicated in the pulmonary-, renal-, dermal- and liver fibrosis as well as in scarring after myocardial infarction. We hypothesize that Wnt/β-catenin signaling contributes to cardiac fibroblast (CF) activation and β-catenin loss-of-function (βLOF) in CFs reduces fibrosis and preserves cardiac function. Methods and Results: The role of Wnt/β-catenin signaling in CF activation was studied using in vitro CF culture and in vivo genetic manipulation. Postnatal (P)0, P8 and P60 CFs were isolated and cultured. Wnt1 treatment significantly activated CFs, while Wnt inhibition (XAV) completely blocked Wnt1-induced CF activation as determined by αSMA staining. Interestingly, XAV also partially abrogated CF activation induced by TGFβ. In vivo, PeriostinMerCreMer (Pn) or Tcf21MerCreMer (T21) mice were crossbred with βLOF and ROSAmTmG. At baseline, CFs were labeled by T21 but minimal activity was observed with Pn. Accumulation of CFs labeled by Pn or T21 Cres was observed in myocardium 8 weeks after TAC. Inducible CF-specific βLOF transgenic mice (Pn-βLOF or T21-βLOF) were subjected to transverse aortic constriction (TAC) or sham surgeries. βLOF was induced post-surgery via tamoxifen. In sham-operated mice, no difference in cardiac function or morphology was observed between βLOF and control mice. In mice subjected to TAC, cardiac function, as measured by echocardiography, was significantly improved, and the interstitial and peri-vascular fibrosis, as well as heart weight to tibia length ratios, were significantly reduced in the βLOF group, compared to controls, 8 weeks after TAC. Thus, induction of βLOF in CFs after TAC leads to improved cardiac performance, decreased fibrosis, and reduced maladaptive cardiac remodeling. Conclusions: βLOF in CFs inhibits myo-fibroblast activation, reduces cardiac fibrosis and preserves cardiac function in TAC induced cardiac injury.


2013 ◽  
Vol 305 (7) ◽  
pp. H1010-H1019 ◽  
Author(s):  
Catherine L. Passariello ◽  
Marjorie Gayanilo ◽  
Michael D. Kritzer ◽  
Hrishikesh Thakur ◽  
Zoharit Cozacov ◽  
...  

Myocardial interstitial fibrosis is an important contributor to the development of heart failure. Type 3 p90 ribosomal S6 kinase (RSK3) was recently shown to be required for concentric myocyte hypertrophy under in vivo pathological conditions. However, the role of RSK family members in myocardial fibrosis remains uninvestigated. Transgenic expression of α-tropomyosin containing a Glu180Gly mutation (TM180) in mice of a mixed C57BL/6:FVB/N background induces a cardiomyopathy characterized by a small left ventricle, interstitial fibrosis, and diminished systolic and diastolic function. Using this mouse model, we now show that RSK3 is required for the induction of interstitial fibrosis in vivo. TM180 transgenic mice were crossed to RSK3 constitutive knockout ( RSK3−/−) mice. Although RSK3 knockout did not affect myocyte growth, the decreased cardiac function and mild pulmonary edema associated with the TM180 transgene were attenuated by RSK3 knockout. The improved cardiac function was consistent with reduced interstitial fibrosis in the TM180; RSK3−/− mice as shown by histology and gene expression analysis, including the decreased expression of collagens. The specific inhibition of RSK3 should be considered as a potential novel therapeutic strategy for improving cardiac function and the prevention of sudden cardiac death in diseases in which interstitial fibrosis contributes to the development of heart failure.


2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Christopher J Traynham ◽  
Ancai Yuan ◽  
Erhe Gao ◽  
Walter Koch

In the next 35 years, the global population of individuals above 60 years of age will double to approximately 2 billion. In the aged population, cardiovascular diseases are known to occur at a higher prevalence ultimately leading to increased mortality. G protein-coupled receptors (GPCRs) have been identified as vital regulators of cardiac function. GPCR kinases (GRKs) are important in cardiac GPCR regulation through desensitization of these receptors. GRK2 is highly expressed in the heart, and has been widely characterized due to its upregulation in heart failure. Studies from our lab have shown that elevated GRK2 levels in ischemia-reperfusion (I/R) injury result in a pro-death phenotype. Interestingly, cardio-protection can be inferred via S-nitrosylation of GRK2 at cysteine 340. Further, we have generated a knock-in GRK2 340S mouse, in which cysteine 340 was mutated to block dynamic GRK2 S-nitrosylation. GRK2 340S mice are more susceptible to I/R injury. Given that GRK2 340S mice are more susceptible to oxidative stress, and there is a nitroso-redox imbalance in senescence, it is possible that these mice are more likely to exhibit decreased cardiac performance as they age. Therefore, we hypothesize that with age GRK2 340S knockin mice will develop an overall worsened cardiac phenotype compared to control wild-type (WT) mice. To test this hypothesis, 340S and WT mice were aged for a year, and cardiac function was evaluated via echocardiography. Aged 340S mice exhibited significantly decreased ejection fraction and fraction shortening relative to aged WT controls. Prior to tissue harvesting, in-vivo hemodynamics was conducted via Millar catheterization. At baseline, aged 340S mice exhibited increased systolic blood pressure compared to aged WT mice. At the conclusion of this protocol, mice were sacrificed and heart weight (HW), body weight (BW), and tibia length (TL) measured to evaluate cardiac hypertrophy. Aged 340S mice exhibited significantly increased HW/BW and HW/TL ratios, indicative of cardiac hypertrophy, relative to aged WT controls. Taken together, these data suggest that with age, loss of the cardio protection inferred by S-nitrosylation of GRK2 at leads to decreased cardiac performance, and an overall worsened cardiac phenotype.


Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Michael R Morissette ◽  
Janelle C Stricker ◽  
Anthony Rosenzweig

Myostatin (MSTN) is a well-known negative regulator of skeletal muscle mass, and MSTN inhibition is being considered as therapy for multiple conditions associated with muscle wasting, including sarcopenia of aging. We have previously shown that MSTN inhibits phenylephrine-induced cardiomyocyte hypertrophy, however whether MSTN has a physiological role in regulating cardiac hypertrophy or function at baseline or with aging remains unclear. To determine if MSTN is dynamically regulated with aging, we performed QRT-PCR on hearts from male wild-type (WT) senescent mice (24 months old (mos)) and rats (32 mos). MSTN mRNA levels were increased in old versus young (4 mos) hearts (2.5- and 4-fold respectively, p<0.05). To study the functional significance of MSTN in aging, we maintained germline MSTN-knockout mice (MSTN −/− ) and their WT littermates for 24 –27 months. We found no difference in heart weight of aged male MSTN −/− compared to WT mice (162.5±17.0 (n=4) vs 153.2±4.2 (n=4) mg, p=0.51), which would argue against an inhibitory role for MSTN in age-related increases in cardiac mass. We also performed echocardiography on unanesthetized senescent MSTN −/− and WT mice. MSTN −/− mice had better fractional shortening (58.1±2.0 (n=7) vs 49.4±1.2 (n=8) %, p=0.002) and smaller LV end-diastolic diameter (3.41±0.19 vs 2.71±0.14 mm, p=0.012) compared to WT. The decreased cardiac function seen in aged WT mice was associated with increased cardiac fibrosis on Masson-Trichrome stained sections. Western blot analysis also demonstrated a 3.3-fold increase in phospholamban phosphorylation in MSTN −/− hearts (p<0.05), compared to WT, while no differences in SERCA2a or calsequestrin protein levels were seen. We conclude that MSTN increases in the heart with aging, and that genetic deletion of MSTN results in improved cardiac function without a difference in heart mass in senescent mice. Decreased cardiac fibrosis and increased inhibition (phosphorylation) of phospholamban likely contribute to the better cardiac function seen in senescent MSTN −/− mice. These results suggest that inhibiting MSTN for sarcopenia in the elderly may also benefit cardiac function and could represent a novel therapeutic approach for ameliorating cardiac dysfunction and/or fibrosis. This research has received full or partial funding support from the American Heart Association, AHA Founders Affiliate (Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island, Vermont).


2001 ◽  
Vol 280 (4) ◽  
pp. H1782-H1792 ◽  
Author(s):  
Xiaomin Zhang ◽  
Gohar Azhar ◽  
Jianyuan Chai ◽  
Pamela Sheridan ◽  
Koichiro Nagano ◽  
...  

Serum response factor (SRF), a member of the MCM1, agamous, deficiens, SRF (MADS) family of transcriptional activators, has been implicated in the transcriptional control of a number of cardiac muscle genes, including cardiac α-actin, skeletal α-actin, α-myosin heavy chain (α-MHC), and β-MHC. To better understand the in vivo role of SRF in regulating genes responsible for maintenance of cardiac function, we sought to test the hypothesis that increased cardiac-specific SRF expression might be associated with altered cardiac morphology and function. We generated transgenic mice with cardiac-specific overexpression of the human SRF gene. The transgenic mice developed cardiomyopathy and exhibited increased heart weight-to-body weight ratio, increased heart weight, and four-chamber dilation. Histological examination revealed cardiomyocyte hypertrophy, collagen deposition, and interstitial fibrosis. SRF overexpression altered the expression of SRF-regulated genes and resulted in cardiac muscle dysfunction. Our results demonstrate that sustained overexpression of SRF, in the absence of other stimuli, is sufficient to induce cardiac change and suggest that SRF is likely to be one of the downstream effectors of the signaling pathways involved in mediating cardiac hypertrophy.


2003 ◽  
Vol 81 (2) ◽  
pp. 125-128 ◽  
Author(s):  
Ghada S Hassan ◽  
Fazila Chouiali ◽  
Takayuki Saito ◽  
Fu Hu ◽  
Stephen A Douglas ◽  
...  

Recent studies have shown that the vasoactive peptide urotensin-II (U-II) exerts a wide range of action on the cardiovascular system of various species. In the present study, we determined the in vivo effects of U-II on basal hemodynamics and cardiac function in the anesthetized intact rat. Intravenous bolus injection of human U-II resulted in a dose-dependent decrease in mean arterial pressure and left ventricular systolic pressure. Cardiac contractility represented by ±dP/dt was decreased after injection of U-II. However, there was no significant change in heart rate or diastolic pressure. The present study suggests that upregulation of myocardial U-II may contribute to impaired myocardial function in disease conditions such as congestive heart failure.Key words: urotensin-II, rat, infusion, heart.


Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Maria Cimini ◽  
venkata naga srikanth garikipati ◽  
Andrea Elia ◽  
Chunlin Wang ◽  
MAY TRUONGCAO ◽  
...  

Superseding fibrosis through paracrine signals enhances the ventricular dysfunction aftermyocardial infarction (MI). We have earlier reported that within 2 days post-MI a cohort ofpodoplanin (PDPN), a platelet aggregation-inducing type I transmembrane glycoprotein,positive cells populate injured heart and enhance inflammatory response by physicalinteractions with monocytes. Here we explored whether exosomes from these cells couldindependently alter healthy heart physiology and structure. PDPN+ cells were isolated 2 daysafter MI, cultured expanded and activated with TNFα and AngiotensinII. Exosomes derived fromactivated PDPN+ cells conditioned media were used in vitro treatment of mouse cardiacendothelial cells (mCECs), mouse embryonic fibroblast (MEF) and monocytes and in vivo forthe treatment of healthy mouse hearts. PDPN+ cells derived exosomes (PDPN-exo)reprogramed mCECs to the lymphatic phenotype enhancing the expression of the majorlymphatic lineage markers and upregulated the expression of fibrotic markers suggesting anendothelial-mesenchymal transition. Furthermore, PDPN-exo drove the MEF to myo-fibroblastphenotype and monocytes toward pro-inflammatory phenotype. Proteomic analysis of PDPN-exo suggest these transitions may depend on NOTCH cleavage trough β-γSecretase. In vivo,PDPN-exo were initially injected into the left ventricle of healthy mouse hearts followed withexosomes boosters delivered by retro-orbital vein injection. Treated mice developed anextended epicardial fibrosis with a subsequent impairment in the contractility and increase ofthe end diastolic and systolic volumes. The fibrotic area was characterized by vessels doublepositive to endothelial and lymphatic endothelial markers, and infiltrating CD45+ cells. Inconclusion these data suggest that PDPN-exo alter the biology of mCECs, fibroblast andmonocytes and participate in adverse remodeling after MI; their specific cargo may representa cohort of targets for the treatment of cardiac fibrosis.


2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Jie Ni ◽  
Yihai Liu ◽  
Lina Kang ◽  
Lian Wang ◽  
Zhonglin Han ◽  
...  

AbstractHuman trophoblast stem cells (TSCs) have been confirmed to play a cardioprotective role in heart failure. However, whether trophoblast stem cell-derived exosomes (TSC-Exos) can protect cardiomyocytes from doxorubicin (Dox)-induced injury remains unclear. In the present study, TSC-Exos were isolated from the supernatants of human trophoblasts using the ultracentrifugation method and characterized by transmission electron microscopy and western blotting. In vitro, primary cardiomyocytes were subjected to Dox and treated with TSC-Exos, miR-200b mimic or miR-200b inhibitor. Cellular apoptosis was observed by flow cytometry and immunoblotting. In vivo, mice were intraperitoneally injected into Dox to establish a heart failure model. Then, different groups of mice were administered either PBS, adeno-associated virus (AAV)-vector, AAV-miR-200b-inhibitor or TSC-Exos via tail vein injection. Then, the cardiac function, cardiac fibrosis and cardiomyocyte apoptosis in each group were evaluated, and the downstream molecular mechanism was explored. TSC-Exos and miR-200b inhibitor both decreased primary cardiomyocyte apoptosis. Similarly, mice receiving TSC-Exos and AAV-miR-200b inhibitor exhibited improved cardiac function, accompanied by reduced apoptosis and inflammation. The bioinformatic prediction and luciferase reporter results confirmed that Zeb1 was a downstream target of miR-200b and had an antiapoptotic effect. TSC-Exos attenuated doxorubicin-induced cardiac injury by playing antiapoptotic and anti-inflammatory roles. The underlying mechanism could be an increase in Zeb1 expression by the inhibition of miR-200b expression. In summary, this study sheds new light on the application of TSC-Exos as a potential therapeutic tool for heart failure.


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