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postgraduate thesis: The role of protein kinase C beta 2 (PKC β2) in myocardial ischaemia-reperfusion injury
Title | The role of protein kinase C beta 2 (PKC β2) in myocardial ischaemia-reperfusion injury |
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Authors | |
Issue Date | 2014 |
Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
Citation | Jin, J. [金冀琴]. (2014). The role of protein kinase C beta 2 (PKC β2) in myocardial ischaemia-reperfusion injury. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5387951 |
Abstract | Background:
Myocardial ischaemia and reperfusion (I/R) injury, a major global public health problem, is associated with significant morbidity and mortality. Diabetic hearts are more sensitive to I/R and consequently are associated with greater morbidity and mortality, while a number of cardioprotective interventions such as ischaemia preconditioning and ischaemia post-conditioning are partly lost or are completely abolished in diabetes.
Objectives:
I investigated the role of protein kinase C beta 2 (PKC β2) in diabetes induced heart sensitization after I/R and explored the underlying mechanism. Also, I investigated whether remifentanil preconditioning (RPC) ameliorates myocardial infarct size in diabetic rats.
Materials and methods:
Diabetic rats model was established with streptozotocin (STZ) while ruboxistaurin (RBX), CGP-53353 (CGP), and siRNA of PKC β2 were induced in diabetic rats or high glucose-exposed H9C2 cells to investigate the relationship between PKC β2 and myocardial I/R injury with following indexes including cardiac function, myocardial infarct size, cell apoptosis, concentrations of Creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH), and mitochondrial membrane potential. The siRNA of caveolin (Cav-3) and Akt were used in H9C2 cells to detect the mechanism of PKC β2 induced aggravating myocardial I/R injury. Both in diabetic rats and high glucose-exposed H9C2 cells, cardiac protective ability of RPC were measured. The naloxone and caveolin (Cav-3) siRNA were used in RPC to detect the mechanism of RPC. The proteins expression of PKCβ2, Cav-3, Akt, and cleaved caspase 3 were measured by western blot.
Results:
The expression of PKC β2 was significantly up regulated in diabetes after acute myocardial I/R. In diabetic rats, RBX markedly reduced myocardial infarct size and apoptotic cells. RBX also restored left ventricular functions and decreased concentrations of CK-MB and LDH after I/R. In high glucose-exposed H9C2 cells, both CGP and PKC β2 siRNA decreased apoptotic cells and impaired mitochondrion after hypoxia and reoxygenation (H/R). Cav-3 siRNA or Akt siRNA aggravated cell apoptosis and mitochondrial injury after H/R. Proteins expression of Cav-3 and Akt were increased after RBX treatment in diabetic I/R model. Furthermore, RPC attenuated myocardial infarct size and restored cardiac systolic ability in non-diabetic rats. RPC decreased apoptotic cardiomyocytes and attenuated mitochondrial injury in cultured cardiomyocytes. Activation of Akt and Bcl-2 were involved in RPC. Naloxone and Cav-3 siRNA blocked the cardioprotection of RPC against myocardial I/R injury. RPC failed to ameliorate myocardial infarct size in diabetic rats and did not decrease high glucose-exposed H9C2 cell apoptosis after H/R.
Conclusions:
The high expression of PKC β2 contributed to diabetic hearts being more sensitive to I/R. RBX ameliorates myocardial I/R injury by attenuating post-reperfusion myocardial infarct size and cardiac dysfunction. The plausible mechanism underlying the RBX-induced cardioprotection was through the regulation of PKCβ2-mediated signalling pathway in apoptosis under the hyperglycaemic conditions. Cav-3 level was important for PKCβ2-mediated cardioprotection of Akt activation. Low expression of Cav-3 in diabetes might be an essential reason why RPC failed to provide cardiac protection in diabetes. |
Degree | Doctor of Philosophy |
Subject | Ischemia Protein kinases Reperfusion injury |
Dept/Program | Anaesthesiology |
Persistent Identifier | http://hdl.handle.net/10722/222197 |
HKU Library Item ID | b5387951 |
DC Field | Value | Language |
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dc.contributor.author | Jin, Jiqin | - |
dc.contributor.author | 金冀琴 | - |
dc.date.accessioned | 2016-01-02T23:25:54Z | - |
dc.date.available | 2016-01-02T23:25:54Z | - |
dc.date.issued | 2014 | - |
dc.identifier.citation | Jin, J. [金冀琴]. (2014). The role of protein kinase C beta 2 (PKC β2) in myocardial ischaemia-reperfusion injury. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5387951 | - |
dc.identifier.uri | http://hdl.handle.net/10722/222197 | - |
dc.description.abstract | Background: Myocardial ischaemia and reperfusion (I/R) injury, a major global public health problem, is associated with significant morbidity and mortality. Diabetic hearts are more sensitive to I/R and consequently are associated with greater morbidity and mortality, while a number of cardioprotective interventions such as ischaemia preconditioning and ischaemia post-conditioning are partly lost or are completely abolished in diabetes. Objectives: I investigated the role of protein kinase C beta 2 (PKC β2) in diabetes induced heart sensitization after I/R and explored the underlying mechanism. Also, I investigated whether remifentanil preconditioning (RPC) ameliorates myocardial infarct size in diabetic rats. Materials and methods: Diabetic rats model was established with streptozotocin (STZ) while ruboxistaurin (RBX), CGP-53353 (CGP), and siRNA of PKC β2 were induced in diabetic rats or high glucose-exposed H9C2 cells to investigate the relationship between PKC β2 and myocardial I/R injury with following indexes including cardiac function, myocardial infarct size, cell apoptosis, concentrations of Creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH), and mitochondrial membrane potential. The siRNA of caveolin (Cav-3) and Akt were used in H9C2 cells to detect the mechanism of PKC β2 induced aggravating myocardial I/R injury. Both in diabetic rats and high glucose-exposed H9C2 cells, cardiac protective ability of RPC were measured. The naloxone and caveolin (Cav-3) siRNA were used in RPC to detect the mechanism of RPC. The proteins expression of PKCβ2, Cav-3, Akt, and cleaved caspase 3 were measured by western blot. Results: The expression of PKC β2 was significantly up regulated in diabetes after acute myocardial I/R. In diabetic rats, RBX markedly reduced myocardial infarct size and apoptotic cells. RBX also restored left ventricular functions and decreased concentrations of CK-MB and LDH after I/R. In high glucose-exposed H9C2 cells, both CGP and PKC β2 siRNA decreased apoptotic cells and impaired mitochondrion after hypoxia and reoxygenation (H/R). Cav-3 siRNA or Akt siRNA aggravated cell apoptosis and mitochondrial injury after H/R. Proteins expression of Cav-3 and Akt were increased after RBX treatment in diabetic I/R model. Furthermore, RPC attenuated myocardial infarct size and restored cardiac systolic ability in non-diabetic rats. RPC decreased apoptotic cardiomyocytes and attenuated mitochondrial injury in cultured cardiomyocytes. Activation of Akt and Bcl-2 were involved in RPC. Naloxone and Cav-3 siRNA blocked the cardioprotection of RPC against myocardial I/R injury. RPC failed to ameliorate myocardial infarct size in diabetic rats and did not decrease high glucose-exposed H9C2 cell apoptosis after H/R. Conclusions: The high expression of PKC β2 contributed to diabetic hearts being more sensitive to I/R. RBX ameliorates myocardial I/R injury by attenuating post-reperfusion myocardial infarct size and cardiac dysfunction. The plausible mechanism underlying the RBX-induced cardioprotection was through the regulation of PKCβ2-mediated signalling pathway in apoptosis under the hyperglycaemic conditions. Cav-3 level was important for PKCβ2-mediated cardioprotection of Akt activation. Low expression of Cav-3 in diabetes might be an essential reason why RPC failed to provide cardiac protection in diabetes. | - |
dc.language | eng | - |
dc.publisher | The University of Hong Kong (Pokfulam, Hong Kong) | - |
dc.relation.ispartof | HKU Theses Online (HKUTO) | - |
dc.rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works. | - |
dc.rights | This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. | - |
dc.subject.lcsh | Ischemia | - |
dc.subject.lcsh | Protein kinases | - |
dc.subject.lcsh | Reperfusion injury | - |
dc.title | The role of protein kinase C beta 2 (PKC β2) in myocardial ischaemia-reperfusion injury | - |
dc.type | PG_Thesis | - |
dc.identifier.hkul | b5387951 | - |
dc.description.thesisname | Doctor of Philosophy | - |
dc.description.thesislevel | Doctoral | - |
dc.description.thesisdiscipline | Anaesthesiology | - |
dc.description.nature | published_or_final_version | - |
dc.identifier.doi | 10.5353/th_b5387951 | - |
dc.identifier.mmsid | 991041091959703414 | - |