Abstract 144: Cardiac Expression of Mitochondrial Acetyltransferase Gcn5l1 Contributes to Ischemia-Reperfusion Injury and Alters Mitochondrial Energetics After Injury

2017 ◽  
Vol 121 (suppl_1) ◽  
Author(s):  
Janet R Manning ◽  
Dharendra Thapa ◽  
Manling Zhang ◽  
Michael W Stoner ◽  
Iain Scott
Keyword(s):  
Heart Failure ◽  
Reperfusion Injury ◽  
Protein Function ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Mitochondrial Protein ◽  
Ischemic Heart ◽  
Mitochondrial Proteins ◽  
Ros Production ◽  
Triphenyltetrazolium Chloride

Introduction: The increasing global burden of ischemic heart disease demands a closer examination of the mechanisms by which myocardial reperfusion produces injury to initiate long-term heart failure. Reactive oxygen species (ROS) generated after ischemia reperfusion (IR), in conjunction with the dysfunction of mitochondrial metabolic enzymes, have been identified as a primary mediator of cardiac reperfusion injury. The acetylation of mitochondrial proteins, regulated by opposing actions of NAD + -dependent sirtuin deacetylases and the recently identified mitochondrial acetyltransferase GCN5L1, has emerged as a key point of intersection between nutrient status and mitochondrial protein function in cardiomyoctyes. This makes the association between acetylation and ROS production an important topic of investigation. Intriguingly, global protein acetylation was recently reported to be upregulated in the hearts of human patients with ischemic heart failure. Despite this, it remains unknown whether GCN5L1 acetyltransferase activity plays a role in the regulation of metabolic proteins during IR injury. Hypothesis: Cardiac deletion of the acetyltransferase GCN5L1 reduces the acetylation of mitochondrial proteins during IR, reducing aberrant activity and preventing ROS production. Methods: Isolated work-performing hearts from cardiac-specific inducible GCN5L1 knockout mice were subjected to global ischemia and reperfusion. Contractility (+/- dP/dT) of the left ventricle was measured throughout as an index of post IR functional recovery. Tissue damage was assessed by measuring the release of lactate dehydrogenase and post-reperfusion staining of viable tissue with triphenyltetrazolium chloride. Acetylation levels of mitochondrial proteins were measured during IR using immunoblotting of homogenized hearts, which were also used to evaluate ROS production. Results and Conclusions: Mitochondrial acetylation was decreased in GCN5L1 hearts compared to WT, coinciding with improved post-IR recovery. We therefore conclude that acetylation of mitochondrial proteins by the acetyltransferase GCN5L1 is an important regulatory mechanism of IR-induced, ROS-mediated damage.

Abstract 428: Pharmacologic and Activated Fibroblast-specific Gβγ-GRK2 Inhibition is Protective Following Ischemia Reperfusion Injury

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Joshua G Travers ◽  
Fadia A Kamal ◽  
Michelle L Nieman ◽  
Michelle A Sargent ◽  
Jeffery D Molkentin ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiac Function ◽  
Reperfusion Injury ◽  
G Protein ◽  
Knockout Mice ◽  
Ischemia Reperfusion Injury ◽  
Interstitial Fibrosis ◽  
Myocardial Dysfunction ◽  
Ischemia Reperfusion ◽  
Ventricular Compliance

Heart failure is a devastating disease characterized by chamber remodeling, interstitial fibrosis and reduced ventricular compliance. Cardiac fibroblasts are responsible for extracellular matrix homeostasis, however upon injury or pathologic stimulation, these cells transform to a myofibroblast phenotype and play a fundamental role in myocardial fibrosis and remodeling. Chronic sympathetic overstimulation induces excess signaling through G protein βγ subunits and ultimately the pathologic activation of G protein-coupled receptor kinase 2 (GRK2). We hypothesized that Gβγ-GRK2 inhibition plays an important role in the cardiac fibroblast to attenuate pathologic myofibroblast activation and cardiac remodeling. To investigate this hypothesis, mice were subjected to ischemia/reperfusion (I/R) injury and treated with the small molecule Gβγ-GRK2 inhibitor gallein. While animals receiving vehicle demonstrated a reduction in overall cardiac function as measured by echocardiography, mice treated with gallein exhibited nearly complete preservation of cardiac function and reduced fibrotic scar formation. We next sought to establish the cell specificity of this compound by treating inducible cardiomyocyte- and activated fibroblast-specific GRK2 knockout mice post-I/R. Although we observed modest restoration in cardiac function in cardiomyocyte-specific GRK2 null mice, treatment of these mice with gallein resulted in further protection against myocardial dysfunction following injury, suggesting a functional role in other cardiac cell types, including fibroblasts. Activated fibroblast-specific GRK2 knockout mice were also subjected to ischemia/reperfusion injury; these animals displayed preserved myocardial function and reduced collagen deposition compared to littermate controls following injury. Furthermore, systemic Gβγ-GRK2 inhibition by gallein did not appear to confer further protection over activated fibroblast-specific GRK2 ablation alone. In summary, these findings suggest a potential therapeutic role for Gβγ-GRK2 inhibition in limiting pathologic myofibroblast activation, interstitial fibrosis and heart failure progression.

Abstract 16598: The Role of Paraoxonase 2 in Myocardial Ischemia/Reperfusion Injury

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Jingyuan Li ◽  
Victor R Grijalva ◽  
Srinivasa T Reddy ◽  
Mansoureh Eghbali
Keyword(s):  
Myocardial Ischemia ◽  
Infarct Size ◽  
Er Stress ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Ros Production ◽  
Myocardial Ischemia Reperfusion Injury ◽  
Myocardial Ischemia Reperfusion

Objectives: Paraoxonases (PON) gene family consists of three proteins PON1, PON2, and PON3. PON2 is an intracellular membrane-associated protein that is widely expressed in vascular cells and many tissues. At the subcellular level, PON2 is localized to both the ER and mitochondria, and protects against oxidative stress. Hypothesis: The aim of this study was to investigate the role of PON2 in myocardial ischemia reperfusion injury. Methods: PON2 deficient (PON2-/-) and WT male mice were subjected to in-vivo ischemia/reperfusion injury. The left anterior descending coronary artery was occluded for 30 min followed by 24 hr of reperfusion. The infarct size, mitochondrial calcium retention capacity (CRC) and reactive oxygen species (ROS) generation were measured. The expression of C/EBP homologous protein (CHOP), GSK3b and phosphate GSK3b protein were examined by Western Blot. The number of animals was 5-7/group and data were expressed as mean±SEM. T test were used for statistical analysis. Probability values <0.05 were considered statistically significant. Results: The infarct size was ~2 fold larger in PON2 deficient mice compared to WT mice (p<0.05). The threshold for opening of mitochondrial permeability transition pore (mPTP) in response to calcium overload was much lower in PON2-/- mice compared with WT mice (173±19 in PON2-/-, 250±41 in WT, nmol/mg-mitochondrial protein, p<0.05). The ROS production was ~2 fold higher in isolated cardiac mitochondria from PON2-/- mice compared with WT mice (p<0.05). ER stress protein CHOP increased significantly in PON2-/- mice compared to WT mice (normalized to WT: 1±0.05 in WT, 1.66±0.08 in PON2-/-, p<0.001). Phospho-GSK3b level was significantly downregulated in in PON2-/- mice compared to WT mice (pGSK3b/GSK3b normalized to WT: 1±0.06 in WT 0.67±0.08 in PON2-/-, p<0.05). Conclusions: PON2 regulates myocardial ischemia/reperfusion injury via inhibiting the opening of mPTP, which is associated with reduced mitochondria ROS production, deactivation of ER stress signaling CHOP and GSK3b.

scholarly journals Restoring Mitochondrial Function While Avoiding Redox Stress: The Key to Preventing Ischemia/Reperfusion Injury in Machine Perfused Liver Grafts?

2020 ◽  
Vol 21 (9) ◽  
pp. 3132 ◽  
Author(s):  
Julia Hofmann ◽  
Giorgi Otarashvili ◽  
Andras Meszaros ◽  
Susanne Ebner ◽  
Annemarie Weissenbacher ◽  
...  
Keyword(s):  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ex Vivo ◽  
Ischemia Reperfusion ◽  
Graft Function ◽  
Ros Production ◽  
Machine Perfusion ◽  
Redox Stress ◽  
Molecular Events ◽  
Regulate Cell Death

Mitochondria sense changes resulting from the ischemia and subsequent reperfusion of an organ and mitochondrial reactive oxygen species (ROS) production initiates a series of events, which over time result in the development of full-fledged ischemia-reperfusion injury (IRI), severely affecting graft function and survival after transplantation. ROS activate the innate immune system, regulate cell death, impair mitochondrial and cellular performance and hence organ function. Arresting the development of IRI before the onset of ROS production is currently not feasible and clinicians are faced with limiting the consequences. Ex vivo machine perfusion has opened the possibility to ameliorate or antagonize the development of IRI and may be particularly beneficial for extended criteria donor organs. The molecular events occurring during machine perfusion remain incompletely understood. Accumulation of succinate and depletion of adenosine triphosphate (ATP) have been considered key mechanisms in the initiation; however, a plethora of molecular events contribute to the final tissue damage. Here we discuss how understanding mitochondrial dysfunction linked to IRI may help to develop novel strategies for the prevention of ROS-initiated damage in the evolving era of machine perfusion.

scholarly journals Cardioprotective Effect of Novel Matrix Metalloproteinase Inhibitors

2020 ◽  
Vol 21 (19) ◽  
pp. 6990
Author(s):  
Kamilla Gömöri ◽  
Tamara Szabados ◽  
Éva Kenyeres ◽  
Judit Pipis ◽  
Imre Földesi ◽  
...  
Keyword(s):  
Matrix Metalloproteinase ◽  
Infarct Size ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Positive Control ◽  
Matrix Metalloproteinase 2 ◽  
Area At Risk ◽  
Triphenyltetrazolium Chloride

Background: We recently developed novel matrix metalloproteinase-2 (MMP-2) inhibitor small molecules for cardioprotection against ischemia/reperfusion injury and validated their efficacy in ischemia/reperfusion injury in cardiac myocytes. The aim of the present study was to test our lead compounds for cardioprotection in vivo in a rat model of acute myocardial infarction (AMI) in the presence or absence of hypercholesterolemia, one of the major comorbidities affecting cardioprotection. Methods: Normocholesterolemic adult male Wistar rats were subjected to 30 min of coronary occlusion followed by 120 min of reperfusion to induce AMI. MMP inhibitors (MMPI)-1154 and -1260 at 0.3, 1, and 3 µmol/kg, MMPI-1248 at 1, 3, and 10 µmol/kg were administered at the 25th min of ischemia intravenously. In separate groups, hypercholesterolemia was induced by a 12-week diet (2% cholesterol, 0.25% cholic acid), then the rats were subjected to the same AMI protocol and single doses of the MMPIs that showed the most efficacy in normocholesterolemic animals were tested in the hypercholesterolemic animals. Infarct size/area at risk was assessed at the end of reperfusion in all groups by standard Evans blue and 2,3,5-triphenyltetrazolium chloride (TTC) staining, and myocardial microvascular obstruction (MVO) was determined by thioflavine-S staining. Results: MMPI-1154 at 1 µmol/kg, MMPI-1260 at 3 µmol/kg and ischemic preconditioning (IPC) as the positive control reduced infarct size significantly; however, this effect was not seen in hypercholesterolemic animals. MVO in hypercholesterolemic animals decreased by IPC only. Conclusions: This is the first demonstration that MMPI-1154 and MMPI-1260 showed a dose-dependent infarct size reduction in an in vivo rat AMI model; however, single doses that showed the most efficacy in normocholesterolemic animals were abolished by hypercholesterolemia. The further development of these promising cardioprotective MMPIs should be continued with different dose ranges in the study of hypercholesterolemia and other comorbidities.

scholarly journals SIRT3 a Major Player in Attenuation of Hepatic Ischemia-Reperfusion Injury by Reducing ROS via Its Downstream Mediators: SOD2, CYP-D, and HIF-1α

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Gaurav Katwal ◽  
Dilip Baral ◽  
Xiaoli Fan ◽  
He Weiyang ◽  
Xinjiang Zhang ◽  
...  
Keyword(s):  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Bibliographic Databases ◽  
Molecular Pathways ◽  
Remnant Liver ◽  
Ros Production ◽  
Hepatic Ischemia ◽  
Major Player ◽  
Hepatic Ischemia Reperfusion

Reactive oxygen species (ROS) production in hepatic ischemia-reperfusion injury (IRI) is a complex process where multiple cellular and molecular pathways are involved. Few of those molecular pathways are under the direct influence of SIRT3 and its downstream mediators. SIRT3 plays a major role in the mechanism of IRI, and its activation has been shown to attenuate the deleterious effect of ROS during IRI via SOD2-, CYP-D-, and HIF-1α-mediated pathways. The objective of this review is to analyze the current knowledge on SIRT3 and its downstream mediators: SOD2, CYP-D, and HIF-1α, and their role in IRI. For the references of this review article, we have searched the bibliographic databases of PubMed, Web of Science databases, MEDLINE, and EMBASE with the headings “SIRT3,” “SOD2,” “CYP-D,” “HIF-1α,” and “liver IRI.” Priority was given to recent experimental articles that provide information on ROS modulation by these proteins. All the recent advancement demonstrates that activation of SIRT3 can suppress ROS production during IRI through various pathways and few of those are via SOD2, CYP-D, and HIF-1α. This effect can improve the quality of the remnant liver following resection as well as a transplanted liver. More research is warranted to disclose its role in IRI attenuation via this pathway.

Sign in / Sign up

Export Citation Format

Share Document