Abstract 82: Regulation Of Frataxin By HIF-1 In The Ischemic Diabetic Heart

Background: Diabetes is at epidemic proportions, with the major form of fatality due to congestive heart failure triggered by myocardial infarction (MI). The impaired insulin signalling in the diabetic heart leads to myocardial energy dysregulation that compromises the cardioprotective mechanism against ischemic injury. Therefore understanding how mitochondrial energetics is altered in the diabetic ischemic heart would greatly advance the knowledge base for improving outcomes from heart failure in diabetic patients. Methods/Findings: We observed that db/db mice (leptin deficient, type 2 diabetic mice) have increased infarction size (>30%) compared to wild type mice after ischemia/reperfusion (IR) injury by TTC stain. We also found that activity of Hypoxia inducible factor-1 (HIF1) is involved in the cardioprotective response to ischemia, is impaired in db/db hearts. HIF1 is known to transcriptionally regulate genes involved in myocardial energetics. We recently found that HIF1 transcriptionally regulates the mitochondrial protein frataxin (Fxn) in cardiomyocytes as determined by luciferase assays (>3 fold). In vitro studies indicate that hypoxic conditions increase Fxn protein expression in cardiomyocytes as determined by western analysis (2 fold). Fxn plays an important role in the Fe-S cluster biogenesis required for aconitase, succinate dehydrogenase and complexes in the mitochondria. Interestingly, we observed decreased expression of Fxn in the ischemic diabetic heart. Conclusion: we postulate that attenuated HIF1-Fxn signalling in ischemic diabetic heart leads to abnormally enlarged infarction size in response to IR. The decline in HIF-1 activity in response to hypoxia was further validated in cardiomyocytes cultured in high glucose media. The significance for Fxn against hypoxic injury was confirmed by utilizing overexpressed Fxn cardiomyocytes via MTT, ATP and aconitase activity assays. Current and future work: currently we are attempting to identify the HIF response element (HRE) in Fxn promoter to further validate the transcriptional activity of HIF1. In addition, we are completing the IR surgeries on HIF1 KO mice to address the cardioprotective nature of HIF1-Fxn signalling against MI.

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A small molecule HIF-1α stabilizer that accelerates diabetic wound healing

Nature Communications ◽

10.1038/s41467-021-23448-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Guodong Li ◽

Chung-Nga Ko ◽

Dan Li ◽

Chao Yang ◽

Wanhe Wang ◽

...

Keyword(s):

Wound Healing ◽

Small Molecule ◽

Hypoxia Inducible Factor ◽

Diabetic Patients ◽

Diabetic Mice ◽

Impaired Wound Healing ◽

Von Hippel Lindau ◽

Design And Synthesis

AbstractImpaired wound healing and ulcer complications are a leading cause of death in diabetic patients. In this study, we report the design and synthesis of a cyclometalated iridium(III) metal complex 1a as a stabilizer of hypoxia-inducible factor-1α (HIF-1α). In vitro biophysical and cellular analyses demonstrate that this compound binds to Von Hippel-Lindau (VHL) and inhibits the VHL–HIF-1α interaction. Furthermore, the compound accumulates HIF-1α levels in cellulo and activates HIF-1α mediated gene expression, including VEGF, GLUT1, and EPO. In in vivo mouse models, the compound significantly accelerates wound closure in both normal and diabetic mice, with a greater effect being observed in the diabetic group. We also demonstrate that HIF-1α driven genes related to wound healing (i.e. HSP-90, VEGFR-1, SDF-1, SCF, and Tie-2) are increased in the wound tissue of 1a-treated diabetic mice (including, db/db, HFD/STZ and STZ models). Our study demonstrates a small molecule stabilizer of HIF-1α as a promising therapeutic agent for wound healing, and, more importantly, validates the feasibility of treating diabetic wounds by blocking the VHL and HIF-1α interaction.

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Abstract 552: Bradykinin Receptor B1/ Matrix Metalloprotease 3 Pathway is a Novel Target in Preventing Cardiac Ischemia-reperfusion Injury

Circulation Research ◽

10.1161/res.127.suppl_1.552 ◽

2020 ◽

Vol 127 (Suppl_1) ◽

Author(s):

Qin Zhang ◽

Lizhuo Ai ◽

Lifeng Liu ◽

Cristian Betancourt ◽

Maura Knapp ◽

...

Keyword(s):

Heart Failure ◽

Cardiac Function ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Endothelial Barrier ◽

Matrix Metalloprotease ◽

Barrier Dysfunction ◽

Area At Risk ◽

Bradykinin Receptor

Introduction: Impaired endothelial function leads to the progression of heart failure after Ischemia-reperfusion (IR). Kinin activation of bradykinin receptor 1 (B1R), a G protein-coupled receptor that has been found to induce capillary leakage, may serve as a critical mediator in cardiac microvascular barrier dysfunction. However, the underlying mechanisms are not clear. We found that B1R inhibition abolished IR-induced endothelial matrix metalloprotease (MMP3) expression and improved endothelial barrier formation. Thus, we hypothesized that B1R antagonist protects against cardiac IR injury through an MMP3 pathway. Methods and Results: MMP3-/- mice and their littermate controls (WT) were subjected to either cardiac IR or sham control. The baseline characteristics of these mice showed minimal phenotypes. Cardiac function was determined at 3, 7 and 24 days post-IR by echocardiography. The MMP3-/- mice displayed improved cardiac function compared to the control mice, as determined by fractional shortening (26% ± 1.1 MMP3-/- vs. 21% ± 0.9 WT, p<0.05, n=5) and ejection fraction (48% ± 1.9 MMP3-/- vs. 42% ± 2.8.1 WT, p<0.05, n=5), and treating with B1R antagonist (300 μg/Kg) significantly reduced serum MMP3 levels (p<0.01). Compared to the control mice, MMP3-/- mice had significantly less infarction/area at risk 24 hours post-IR demonstrated through TTC staining. In vitro studies revealed that cellular hypoxia-reoxygenation (HR) injury significantly increased both B1R and MMP3 expression levels in primary isolated cardiac mice microvascular endothelial cells (mCMVEC). MMP3 levels were measured via ELISA. Moreover, B1R agonist treatment (1uM) increased MMP3 levels, while the use of the antagonist attenuated the increase of MMP3 in response to HR. Finally, the use of B1R antagonist improved MMP3 induced endothelial barrier dysfunction, which was measured by the electric cell-substrate impedance sensing (ECIS) system. Taken together, the results demonstrated that B1R antagonist abolished IR induced MMP3 induction and that the deletion of MMP3 is protective of cardiac function upon IR injury. Conclusions: MMP3 is a critical regulator of cardiac microvascular barrier function, and B1R/MMP3 could potentially serve as a novel therapeutic target for heart failure in response to IR injury.

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Inhibitor of DNA Binding 1 Is Induced during Kidney Ischemia-Reperfusion and Is Critical for the Induction of Hypoxia-Inducible Factor-1α

BioMed Research International ◽

10.1155/2016/4634386 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 8

Author(s):

Dan Wen ◽

Yan-Fang Zou ◽

Yao-Hui Gao ◽

Qian Zhao ◽

Yin-Yin Xie ◽

...

Keyword(s):

Dna Binding ◽

Ischemia Reperfusion ◽

Hypoxia Inducible Factor ◽

Kidney Injury ◽

Mrna Levels ◽

Hypoxia Inducible Factor 1 ◽

Renal Tubular ◽

Inhibitor Of Dna Binding

In this study, rat models of acute kidney injury (AKI) induced by renal ischemia-reperfusion (I/R) and HK-2 cell models of hypoxia-reoxygenation (H/R) were established to investigate the expression of inhibitor of DNA binding 1 (ID1) in AKI, and the regulation relationship between ID1 and hypoxia-inducible factor 1 alpha (HIF-1α). Through western blot, quantitative real-time PCR, immunohistochemistry, and other experiment methods, the induction of ID1 after renal I/R in vivo was observed, which was expressed mainly in renal tubular epithelial cells (TECs). ID1 expression was upregulated in in vitro H/R models at both the protein and mRNA levels. Via RNAi, it was found that ID1 induction was inhibited with silencing of HIF-1α. Moreover, the suppression of ID1 mRNA expression could lead to decreased expression and transcription of HIF-1αduring hypoxia and reoxygenation. In addition, it was demonstrated that both ID1 and HIF-1αcan regulate the transcription of twist. This study demonstrated that ID1 is induced in renal TECs during I/R and can regulate the transcription and expression of HIF-1α.

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Dapagliflozin suppresses ER stress and improves subclinical myocardial function in diabetes: from bedside to bench

10.2337/figshare.13122956 ◽

2020 ◽

Author(s):

Ada Admin ◽

Jhih-Yuan Shih ◽

Yu-Wen Lin ◽

Sudeshna Fisch ◽

Juei-Tang Cheng ◽

...

Keyword(s):

Heart Failure ◽

Er Stress ◽

Myocardial Function ◽

Sglt2 Inhibitor ◽

Left Ventricular ◽

Diabetic Rat ◽

Lv Function ◽

Diabetic Patients ◽

Symptomatic Heart Failure

Dapagliflozin (DAPA) -- a sodium glucose cotransporter 2 (SGLT2) inhibitor, is approved for treatments of diabetic patients. DAPA-HF trial disclosed its benefits in symptomatic heart failure but the underlying mechanism remains largely unknown. In this longitudinal and prospective study, we investigated changes of left ventricular (LV) functions including speckle tracking in diabetic patients free from symptomatic heart failure post DAPA treatment. Using streptozotocin-induce diabetic rat model, we measured the effects of DAPA on myocardial function. In patients with diabetes, following six months of DAPA, despite no significant changes LV ejection fraction, the diastolic function and longitudinal strain improved. Likewise, compared to control, the diabetic rat heart developed pronounced fibrosis, a decline in strain and overall hemodynamics, all of which were mitigated by DAPA treatment. In contrast, despite insulin exerting a glucose lowering effect, it failed to improve myocardial function and fibrosis. In our in vitro study, under high glucose cardiomyocytes showed significant activations of apoptosis, reactive oxygen species and ER stress associated proteins, which were attenuated by the co-incubation of DAPA. Mechanistically, DAPA suppressed ER stress, reduced myocardial fibrosis and improved overall function. The results can lead to further improvement in management of LV function in diabetic patients.

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Dapagliflozin suppresses ER stress and improves subclinical myocardial function in diabetes: from bedside to bench

10.2337/figshare.13122956.v2 ◽

2020 ◽

Author(s):

Ada Admin ◽

Jhih-Yuan Shih ◽

Yu-Wen Lin ◽

Sudeshna Fisch ◽

Juei-Tang Cheng ◽

...

Keyword(s):

Heart Failure ◽

Er Stress ◽

Myocardial Function ◽

Sglt2 Inhibitor ◽

Left Ventricular ◽

Diabetic Rat ◽

Lv Function ◽

Diabetic Patients ◽

Symptomatic Heart Failure

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Cardioprotective mechanism of FTY720 in ischemia reperfusion injury

Journal of Basic and Clinical Physiology and Pharmacology ◽

10.1515/jbcpp-2019-0063 ◽

2019 ◽

Vol 30 (5) ◽

Cited By ~ 1

Author(s):

Naseer Ahmed

Keyword(s):

Heart Failure ◽

Reperfusion Injury ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Myocardial Damage ◽

New Drugs ◽

Mortality And Morbidity ◽

Coronary Syndrome

Abstract Cardioprotection is a very challenging area in the field of cardiovascular sciences. Myocardial damage accounts for nearly 50% of injury due to reperfusion, yet there is no effective strategy to prevent this to reduce the burden of heart failure. During last couple of decades, by combining genetic and bimolecular studies, many new drugs have been developed to treat hypertension, heart failure, and cancer. The use of percutaneous coronary intervention has reduced the mortality and morbidity of acute coronary syndrome dramatically. However, there is no standard therapy available that can mitigate cardiac reperfusion injury, which contributes to up to half of myocardial infarcts. Literature shows that the activation of sphingosine receptors, which are G protein-coupled receptors, induces cardioprotection both in vitro and in vivo. The exact mechanism of this protection is not clear yet. In this review, we discuss the mechanism of ischemia reperfusion injury and the role of the FDA-approved sphingosine 1 phosphate drug fingolimod in cardioprotection.

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SIRT3 deficiency exacerbates ischemia-reperfusion injury: implication for aged hearts

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00027.2014 ◽

2014 ◽

Vol 306 (12) ◽

pp. H1602-H1609 ◽

Cited By ~ 116

Author(s):

George A. Porter ◽

William R. Urciuoli ◽

Paul S. Brookes ◽

Sergiy M. Nadtochiy

Keyword(s):

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Mitochondrial Protein ◽

Critical Feature ◽

Age Related ◽

Lysine Deacetylase ◽

Consumption Rates ◽

Vitro Model ◽

Underlying Mechanisms

Ischemia-reperfusion (IR) injury is significantly worse in aged hearts, but the underlying mechanisms are poorly understood. Age-related damage to mitochondria may be a critical feature, which manifests in an exacerbation of IR injury. Silent information regulator of transcription 3 (SIRT3), the major mitochondrial NAD+-dependent lysine deacetylase, regulates a variety of functions, and its inhibition may disrupt mitochondrial function to impact recovery from IR injury. In this study, the role of SIRT3 in mediating the response to cardiac IR injury was examined using an in vitro model of SIRT3 knockdown (SIRT3kd) in H9c2 cardiac-derived cells and in Langendorff preparations from adult (7 mo old) wild-type (WT) and SIRT3+/− hearts and aged (18 mo old) WT hearts. SIRT3kd cells were more vulnerable to simulated IR injury and exhibited a 46% decrease in mitochondrial complex I (Cx I) activity with low O2 consumption rates compared with controls. In the Langendorff model, SIRT3+/− adult hearts showed less functional recovery and greater infarct vs. WT, which recapitulates the in vitro results. In WT aged hearts, recovery from IR injury was similar to SIRT3+/− adult hearts. Mitochondrial protein acetylation was increased in both SIRT3+/− adult and WT aged hearts (relative to WT adult), suggesting similar activities of SIRT3. Also, enzymatic activities of two SIRT3 targets, Cx I and MnSOD, were similarly and significantly inhibited in SIRT3+/− adult and WT aged cardiac mitochondria. In conclusion, decreased SIRT3 may increase the susceptibility of cardiac-derived cells and adult hearts to IR injury and may contribute to a greater level of IR injury in the aged heart.

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Abstract 379: Inhibition of Bcl-x Phosphorylation Prevents Cardiomyocyte Death, Cardiac Remodeling and Heart Failure After Myocardial Infarction

Circulation Research ◽

10.1161/res.117.suppl_1.379 ◽

2015 ◽

Vol 117 (suppl_1) ◽

Author(s):

Michinari Nakamura ◽

Peiyong Zhai ◽

Dominic D Re ◽

Junichi Sadoshima

Keyword(s):

Myocardial Infarction ◽

Heart Failure ◽

Cardiac Remodeling ◽

Ischemia Reperfusion ◽

Resistant Mutant ◽

Cardiac Contraction ◽

Dependent Manner ◽

Infarct Area

Cardiac remodeling promotes heart failure (HF). Cardiomyocyte (CM) death is one of the mechanisms to develop cardiac remodeling. We recently reported that Mst1 phosphorylates Bcl-xL at Ser14, which promotes apoptosis by inducing dissociation of Bcl-xL from Bax and consequent activation of Bax in CMs. Its phosphorylation is increased in response to ischemia-reperfusion (IR) in an Mst1-dependent manner. However, the functional significance of endogenous Bcl-xL phosphorylation remains unclear in vivo. To address this question, knock-in (KI) mice with alanine mutation at Ser14 in Bcl-x were generated. At baseline, cardiac function was similar between wild-type (WT) and heterozygous KI (HKI) mice (EF 76% and 79%, respectively). HKI mice exhibited smaller % infarct area (30%) than WT (43%) (p=0.016) upon IR, suggesting that phosphorylation of endogenous Bcl-xL at Ser14 plays an essential role in mediating IR injury. In order to test the role of Bcl-xL phosphorylation in the development of HF, HKI and WT mice were subjected to permanent ligation of LAD for 4 weeks. During progression of cardiac remodeling, Mst1 was activated in both WT and HKI mice. Phosphorylation of Bcl-xL and Bcl-xS, an alternative transcriptional variant of Bcl-x, both at Ser14, were increased in WT mice, which were abrogated in HKI mice. The infarct area evaluated with TTC staining at Day 1 was similar in WT and HKI mice (59.1% and 61.2%, p=0.65). Four weeks after myocardial infarction (MI), WT mice exhibited lower cardiac contraction (EF 46.5%) and higher LVEDP (10.8mmHg) than those in HKI mice (EF 68.9% and LVEDP 7.0mmHg) (both p<0.05). Scar area and TUNEL-positive CMs were greater in WT (49.0% and 1.6%, respectively) than in HKI mice (29.2% and 0.4%, respectively) (both p<0.05). Cleaved caspase 3 and 9 were significantly increased (3.2- and 5.7-fold, respectively) in WT but not in HKI mice. In vitro experiments with overexpression of phospho-mimicking mutant (Bcl-xS-S14D) showed 13% reduction in cell viability compared with that of phospho-resistant mutant (Bcl-xS-S14A) (p=0.01%). Our results suggest that phosphorylation of Bcl-xL and Bcl-xS at Ser14 contributes to CM death in response to IR and chronic MI in vivo, thereby promoting cardiac remodeling and HF.

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Abstract 17562: GPCR Gβγ Signaling Mediates Renal Dysfunction and Fibrosis in Heart Failure Mice

Circulation ◽

10.1161/circ.132.suppl_3.17562 ◽

2015 ◽

Vol 132 (suppl_3) ◽

Author(s):

Fadia A Kamal ◽

Joshua G Travers ◽

Allison E Schafer ◽

Qing Ma ◽

Prasad Devarajan ◽

...

Keyword(s):

Heart Failure ◽

Chronic Kidney Disease ◽

Kidney Disease ◽

Renal Dysfunction ◽

G Protein ◽

Kidney Diseases ◽

Ischemia Reperfusion ◽

Kidney Injury ◽

Direct Role

Background: Cardiorenal syndrome type 2 (CRS2), the development of chronic kidney disease (CKD) secondary to chronic heart failure (CHF), is clinically associated with increased incidence of organ failure and reduced survival. Heart and kidney damage in CRS2 is greatly caused by chronic stimulation of the adrenergic and endothelin receptors as a result of elevated neurohormonal signaling of the sympathetic nervous system (SNS) and its downstream endothelin (ET) system, respectively. These receptors belong to the superfamily of G protein-coupled receptors (GPCRs). While chronic GPCR stimulation and its associated upregulated interaction between the G-protein βγ subunit (Gβγ), the GPCR-kinase 2 (GRK2) and β-arrestin are known to be central to various cardiovascular diseases, their role in kidney diseases are by far unknown and beg investigation. Objective: CRS2 animal studies utilize combine ischemic cardiac injury and renal injury, which is of poor clinical relevance. Our study investigates: (1) the development of chronic kidney disease (CKD) in a model of non-ischemic CHF without inducing surgical kidney injury, aiming to establish a more clinically relevant CRS2 model. (2) The possible salutary effect of renal GPCR-Gβγ inhibition in CKD developed in the established CRS2 model. Methods and results: We utilized transverse aortic constriction (TAC) as a non-ischemic hypertrophic murine CHF model. Twelve weeks after TAC, mice developed CKD secondary to CHF suggesting a CRS2 model. This was associated with elevated renal GPCR-Gβγ signaling and ET system expression. Importantly, systemic pharmacologic Gβγ inhibition by gallein attenuated these renal pathological changes in parallel with alleviated CHF. A direct effect of gallein on the kidney was subsequently confirmed in a bilateral ischemia reperfusion acute kidney injury (AKI) mouse model where it attenuated renal dysfunction, tissue damage and ET system activation, indicating a direct role for GPCR-Gβγ signaling in AKI. Further, in vitro studies in mouse embryonic fibroblasts showed a key role for ET receptor-Gβγ signaling in fibroblast activation. Conclusion: Our data suggest TAC as a clinically relevant CRS2 model and GPCR-Gβγ inhibition as a novel therapeutic approach for CRS2 and AKI.

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Abstract 358: Hypoxia and Hyperglycemia Induces M 6 A Mrna Methylation in Major Heart Cells

Circulation Research ◽

10.1161/res.127.suppl_1.358 ◽

2020 ◽

Vol 127 (Suppl_1) ◽

Author(s):

Rajesh Kumari ◽

Prabhat Ranjan ◽

Zainab Suleiman ◽

Jing Li ◽

Suresh K Verma

Keyword(s):

Heart Failure ◽

Endothelial Cells ◽

Heart Disease ◽

Cardiovascular Diseases ◽

Neonatal Rat ◽

Diabetic Heart ◽

Diabetic Patients ◽

Heart Cells ◽

Rat Cardiomyocytes ◽

Mrna Methylation

Background: According to American heart association, over 70 % diabetic patients die from heart and stroke related diseases. The term “diabetic heart diseases” includes coronary heart disease, heart failure and diabetic cardiomyopathy in diabetic patients. Epigenetic and epitranscriptomic modifications play critical roles in progress of diabetic heart disease. Recent evidences indicated that m 6 A methylation involved in ischemic cardiomyopathy. But, the role of m 6 A mRNA methylation in cardiovascular diseases along with diabetic co-morbidity factors has not been studied in details. Thus, here we hypothesize that alterations in m 6 A mRNA methylation under hypoxic and hyperglycemic conditions contributes to severity of ischemic heart disease. Method and Results: To address our hypothesis, we have determined the levels of m 6 A mRNA methylation in NRVM, NRVF and HUVEC, HMVE and mouse primary endothelial cells under hypoxic and hyperglycemic conditions. We also examined the m 6 A levels in mice hearts post 5 days of MI. m 6 A mRNA methylation was significantly upregulated both in human and mouse ischemic hearts. Furthermore, hypoxia and hyperglycemia significantly induced m 6 A methylation in neonatal rat cardiomyocytes, fibroblasts, and mouse primary endothelial cells (isolated from WT and db/db mice). Next, we measured the methylation machinery both at RNA and protein levels. Interestingly, in corroboration with our methylation data, the expression of both m 6 A writers (Mettl3 and WTAP) and Readers (YTHDF2) was significantly increased. To determine the target transcripts which were highly methylated post-ischemia, we performed deep sequencing of methylated RNA after their immunoprecipitation using MeRIP-sequencing protocol. Our MeRIP-seq data has suggested a differentially m 6 A methylated targets both in-vitro and in-vivo ischemic sample. Conclusion: Over all, for the first time our data showed that hypoxia and hyperglycemia alters m 6 A mRNA methylation which may contribute to enhance the severity of cardiovascular diseases under hyperglycemic conditions. Further understanding of the mechanisms, may present a novel approach to potentially regulate m 6 A methylation, which may help in preventing/reducing heart failure in diabetic patients.

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