Genetic Mechanisms of Resistance against Cardiac Preconditioning

心脏预适应抵抗的遗传机制

• 批准号: 8698274
• 负责人: Matthias L. Riess
• 金额: --
• 依托单位: CLEMENT J. ZABLOCKI VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8698274
• 关键词: ATP Synthesis Pathway; Affect; African American; Aging; Agonist; Attenuated; Binding Proteins; Blood Vessels; Calcium; Candidate Disease Gene; Cardiac; Cardiac Myocytes; Cardiovascular system; Cell physiology; Chromosomes; Chromosomes, Human, Pair 6; Complement; Complex; Coronary; DNA; Dahl Hypertensive Rats; Disease; Exhibits; Failure; Genes; Genetic; Genetic Models; Genetic Predisposition to Disease; Genotype; Goals; Heart; Individual; Infarction; Injury; Institution; Investigation; Ischemia; Ischemic Preconditioning; K-Series Research Career Programs; Measurement; Measures; Mechanics; Mediating; Medical; Membrane Potentials; Metabolic; Mitochondria; Modeling; Morbidity - disease rate; Muscle Cells; Myocardial; Myocardial Infarction; Myocardial Ischemia; Myocardial tissue; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Norway; Oxidation-Reduction; Oxidative Stress; PPAR gamma; Patients; Peroxisome Proliferator-Activated Receptors; Peroxisome Proliferators; Phenotype; Play; Population; Production; Rattus; Rattus norvegicus; Reactive Oxygen Species; Reperfusion Injury; Reperfusion Therapy; Research; Research Project Grants; Resistance; Role; Signal Pathway; Superoxides; System; Techniques; Testing; Tissue Viability; Variant; Ventricular; Veterans; Wisconsin; base; clinical practice; consomic; functional outcomes; helix-loop-helix protein differentiation inhibitor; human NOS3 protein; inhibitor/antagonist; medical schools; mortality; oxidation; preconditioning; prevent; protein expression; receptor; research study; resistance mechanism; resistant strain; salt sensitive; success; tool

DESCRIPTION (provided by applicant): As a VA anesthesiologist and physiologist I study protection against myocardial infarction, a significant medical problem in aging Veterans. In Ischemic Preconditioning (IPC), for example, several shorter ischemic periods before sustained ischemia/reperfusion (IR) attenuate infarction. Various triggering mechanisms have been described for IPC, including nitric oxide (NO) and superoxide formation. Genetic predisposition, however, may be an important confounding factor when trying to transfer it into clinical practice; while some patients may benefit others do not. Profound differences in ischemic tolerance exist not just among but also within certain species. For example, Dahl Salt Sensitive (SS) rats are more susceptible to IR injury than Brown Norways (BN), making them an ideal model to study the genotype of diseases phenotypically similar to African-American patients. In a unique chromosomal substitution (consomic) model constructed at the Medical College of Wisconsin introgression of BN chromosome 6 into SS renders the resulting SS6BN consomic more IR resistant while narrowing the genetic difference to a single chromosome. This offers an excellent starting point to study the genetic basis of cardioprotective strategies like IPC. Although NO has been implicated in decreasing infarct size in BN vs SS without IPC, it is yet unknown if SS can respond to IPC and if resistance to IPC is related to differences in endothelial NO synthase (eNOS) activity possibly modulated by the DNA-binding protein inhibitor Id2 and the peroxisome proliferator-activated receptor 3 (PPAR3). eNOS can produce NO or superoxide. Both can modulate mitochondrial function, which in turn can function as a trigger and effector of IPC. Thus, my overall hypothesis is that failure/success of cardioprotection by IPC is mediated by genes regulating NO production and mitochondrial function. I therefore propose to use this consomic model to study two specific aims: I) Determine if a different genetic background is responsible for differential cellular and mitochondrial protection by IPC, and II) if eNOS and/or its upstream modulators Id2 and PPAR3 are candidate genes responsible for this differential protection. Four hypotheses are tested: 1) Genes on BN chromosome 6 are necessary for IPC as evidenced by better cardiac function and less infarction in BN & SS6BN vs SS. 2) Genes on BN chromosome 6 are necessary for IPC as evidenced by more efficient mitochondrial function in BN & SS6BN vs SS. 3) Protection of cellular and mitochondrial function by IPC in intact hearts depends on the signaling pathway Id2->PPAR3->eNOS->NO modulated by genes on rat chromosome 6. 4) Differential protection of cellular and mitochondrial function in isolated cardiomyocytes depends on NO availability. Approaches for 1 & 2: Various cardiac and mitochondrial functions, NO production and infarct size are measured in intact, beating hearts to assess quantity and quality of genetically determined protection by IPC. Approaches for 3 & 4: Additional beating heart experiments are conducted in the presence of NOS inhibitors, an NO-donor, or a PPAR3 agonist or antagonist, and differences in Id2, PPAR3, and eNOS expression and NO levels and localization are determined. In addition, different mitochondrial functions in the absence or presence of NO are measured in isolated myocytes to determine the role and origin of NO in mediating differential cellular and mitochondrial protection by IPC in this genetic model. Genetic tools are essential to study the role of genetic predisposition. Correlating functional outcomes, infarct size, and mitochondrial functions with IPC, NO levels, protein expressions and genotype will allow us to define the signaling pathway and role of NO and mitochondrial function in cardioprotection and to delineate the subcellular and mitochondrial phenotypes associated with the cardioprotective genotype variation. This CDA marks the indispensable basis for further investigations on the role of genetics in cardioprotection and will be a critical milestone to achieve investigative independence in cardiovascular research at the VA.

DESCRIPTION (provided by applicant): As a VA anesthesiologist and physiologist I study protection against myocardial infarction, a significant medical problem in aging Veterans. In Ischemic Preconditioning (IPC), for example, several shorter ischemic periods before sustained ischemia/reperfusion (IR) attenuate infarction. Various triggering mechanisms have been described for IPC, including nitric oxide (NO) and superoxide formation. Genetic predisposition, however, may be an important confounding factor when trying to transfer it into clinical practice; while some patients may benefit others do not. Profound differences in ischemic tolerance exist not just among but also within certain species. For example, Dahl Salt Sensitive (SS) rats are more susceptible to IR injury than Brown Norways (BN), making them an ideal model to study the genotype of diseases phenotypically similar to African-American patients. In a unique chromosomal substitution (consomic) model constructed at the Medical College of Wisconsin introgression of BN chromosome 6 into SS renders the resulting SS6BN consomic more IR resistant while narrowing the genetic difference to a single chromosome. This offers an excellent starting point to study the genetic basis of cardioprotective strategies like IPC. Although NO has been implicated in decreasing infarct size in BN vs SS without IPC, it is yet unknown if SS can respond to IPC and if resistance to IPC is related to differences in endothelial NO synthase (eNOS) activity possibly modulated by the DNA-binding protein inhibitor Id2 and the peroxisome proliferator-activated receptor 3 (PPAR3). eNOS can produce NO or superoxide. Both can modulate mitochondrial function, which in turn can function as a trigger and effector of IPC. Thus, my overall hypothesis is that failure/success of cardioprotection by IPC is mediated by genes regulating NO production and mitochondrial function. I therefore propose to use this consomic model to study two specific aims: I) Determine if a different genetic background is responsible for differential cellular and mitochondrial protection by IPC, and II) if eNOS and/or its upstream modulators Id2 and PPAR3 are candidate genes responsible for this differential protection. Four hypotheses are tested: 1) Genes on BN chromosome 6 are necessary for IPC as evidenced by better cardiac function and less infarction in BN & SS6BN vs SS. 2) Genes on BN chromosome 6 are necessary for IPC as evidenced by more efficient mitochondrial function in BN & SS6BN vs SS. 3) Protection of cellular and mitochondrial function by IPC in intact hearts depends on the signaling pathway Id2->PPAR3->eNOS->NO modulated by genes on rat chromosome 6. 4) Differential protection of cellular and mitochondrial function in isolated cardiomyocytes depends on NO availability. Approaches for 1 & 2: Various cardiac and mitochondrial functions, NO production and infarct size are measured in intact, beating hearts to assess quantity and quality of genetically determined protection by IPC. Approaches for 3 & 4: Additional beating heart experiments are conducted in the presence of NOS inhibitors, an NO-donor, or a PPAR3 agonist or antagonist, and differences in Id2, PPAR3, and eNOS expression and NO levels and localization are determined. In addition, different mitochondrial functions in the absence or presence of NO are measured in isolated myocytes to determine the role and origin of NO in mediating differential cellular and mitochondrial protection by IPC in this genetic model. Genetic tools are essential to study the role of genetic predisposition. Correlating functional outcomes, infarct size, and mitochondrial functions with IPC, NO levels, protein expressions and genotype will allow us to define the signaling pathway and role of NO and mitochondrial function in cardioprotection and to delineate the subcellular and mitochondrial phenotypes associated with the cardioprotective genotype variation. This CDA marks the indispensable basis for further investigations on the role of genetics in cardioprotection and will be a critical milestone to achieve investigative independence in cardiovascular research at the VA.