Hyperglycemia Abrogates Ischemic Postconditioning Cardioprotection by Impairing AdipoR1/Caveolin-3/STAT3 Signaling in Diabetic Rats

Self Cite

Background/Aims: Hearts from diabetic subjects are susceptible to myocardial ischemia reperfusion (I/R) injury. Propofol has been shown to protect against myocardial I/R injury due to its antioxidant properties while the underlying mechanism remained incompletely understood. Thus, this study aimed to determine whether or not propofol could attenuate myocardial I/R injury by attenuating mitochondrial dysfunction/damage through upregulating Caveolin (Cav)-3 under hyperglycemia. Methods: Cultured rat cardiomyocyte H9C2 cells were subjected to hypoxia/reoxygenation (H/R) in the absence or presence of propofol under high glucose (HG), and cell viability, lactate dehydrogenase (LDH) and mitochondrial viability as well as creatine kinase-MB (CK-MB), cardiac troponin I (cTnI) and intracellular adenosine triphosphate (ATP) content were measured with colorimetric Enzyme-Linked Immunosorbent Assays. Intracellular levels of oxidative stress was assessed using 2,7-dichlorodihydrofluorescein diacetate (DCF-DA) fluorescent staining and mitochondrial-dependent apoptosis was assessed by detecting mitochondrial membrane potential and the activation of apoptotic caspases 3 and 9. Results: Exposure of cells to HG without or with H/R both significantly increased cell injury, cell apoptosis and enhanced oxidative stress that were associated with mitochondrial dysfunction and decreased Cav-3 protein expression. All these changes were further exacerbated following H/R under HG. Administration of propofol at concentrations from 12.5 to 50 µM but not 100 µM significantly attenuated H/R injury that was associated with increased Cav-3 expression and activation of the prosurvival proteins Akt and STAT3 with the optimal protective effects seen at 50 µM of propofol (P25). The beneficial effects of propofol(P25) were abrogated by Cav-3 disruption with β-methyl-cyclodextrin. Conclusion: Propofol counteracts cardiomyocyte H/R injury by attenuating mitochondrial damage and improving mitochondrial biogenesis through upregulating Cav-3 during hyperglycemia.

Section: Introductionmentioning

confidence: 99%

Propofol Through Upregulating Caveolin-3 Attenuates Post-Hypoxic Mitochondrial Damage and Cell Death in H9C2 Cardiomyocytes During Hyperglycemia

Deng

Wang

Zhang

et al. 2017

Self Cite

“…In diabetes, PKC-ε is over-expressed and activated [22] contributing to the onset of hyperinsulinemia, hyperglycaemia [23] and cardiac remodelling in type-2 diabetic mice [24]. On the other hand, we recently showed that cardiac STAT3 is reduced in diabetic rats [25]. However, the potential causal link between PKC-ε and STAT3 in diabetes has not been explored.…”

Section: Introductionmentioning

confidence: 99%

Repeated Non-Invasive Limb Ischemic Preconditioning Confers Cardioprotection Through PKC-Ԑ/STAT3 Signaling in Diabetic Rats

Wang

et al. 2018

Self Cite

Background/Aims: Protein kinase C(PKC)-ε activation is a mechanism of preconditioning cardioprotection but its role in repeated non-invasive limb ischemic preconditioning (rNLIP) mediated cardioprotection against myocardial ischemia/reperfusion (I/R) injury in diabetes is unknown. Methods: Eight-week streptozotocin-induced diabetic and non-diabetic Sprague-Dawley rats were subjected to I/R without or with rNLIP. In vitro, H9C2 cells were cultured with high glucose (HG) and subjected to hypoxia/re-oxygenation (H/R) without or with PKC-ε or STAT3 gene knock-down in the absence or presence of remote time hypoxia preconditioning (HPC). Results: Diabetic rats displayed larger post-ischemic myocardial infarct size and higher troponin-I release with concomitant cardiac PKC-ԑ overexpression and activation manifested as increased membrane translocation, while phosphorylated STAT3 (p-STAT3) and Akt (p-Akt) were lower compared to non-diabetic rats (all P<0.05). rNLIP reduced infarct size in both non-diabetic and diabetic rats. rNLIP reduced post-ischemic cardiac PKC-ԑ activation in diabetic while increased PKC-ԑ activation in non-diabetic rats, resulting in increased cardiac p-STAT3 and p-Akt. In H9C2 cells, HG increased PKC-ԑ expression and exacerbated post-H/R injury, accompanied with reduced p-STAT3 and p-Akt, which were all reverted by HPC. These HPC protective effects were abolished by either PKC-ԑ or STAT3 gene knock-down, except that PKC-ԑ gene knock-down reverted HG and H/R-induced reduction of p-STAT3. Conclusion: rNLIP attenuates diabetic heart I/R injury by mitigating HG-induced PKC-ԑ overexpression and, subsequently, activating STAT3.

“…Cav3 is the main component of caveolae in cardiac cells, and it was shown to play an important role in maintaining cardiac function [56] and intracellular calcium homeostasis [57]. Furthermore, its dysregulation is involved in the development of arrhythmia, myocardial hypertrophy, and myocardial ischemia/reperfusion injury [17-19].…”

Section: Discussionmentioning

confidence: 99%

Abnormal Downregulation of Caveolin-3 Mediates the Pro-Fibrotic Action of MicroRNA-22 in a Model of Myocardial Infarction

Zhang¹,

Yin²,

Jiao³

et al. 2018

Background/Aims: Cardiac fibrosis is an important cardiac remodeling event that can ultimately lead to the development of severe arrhythmia and heart failure. MicroRNAs (miRNAs) are involved in the pathogenesis of many cardiovascular diseases. Here, we aimed to investigate the effects of caveolin-3 (Cav3) on the pathogenesis of cardiac fibrosis and the underlying molecular mechanisms. Methods: Cav3 expression was decreased in cardiac fibrosis in vivo and in vitro model. To investigate the role of Cav3 in cardiac fibrosis, we transfected cardiac fibroblasts (CFs) with the siRNA of Cav3 and Cav3-overexpressing plasmid. The collagen content and proliferation of CFs were detected by qRT-PCR, western blot, MTT, and immunofluorescence. A luciferase reporter gene assay and gain/loss of function were used to detect the relationship between miR-22 and Cav3. Results: Cav3 depletion in CFs induced an increase in collagen content, cell proliferation, and phenotypic conversion of fibroblasts to myofibroblasts. Conversely, Cav3 overexpression in CFs was shown to inhibit angiotensin II-mediated excessive collagen deposition through protein kinase C (PKC)ε inactivation. Cav3 was experimentally confirmed as a direct target of miR-22, containing two seed binding sites in its 3′-untranslated region, and miR-22 was demonstrated to be significantly upregulated in the ischemic border zone in mice after myocardial infarction and in neonatal rat CFs pretreated with angiotensin II. miR-22 overexpression increased CFs proliferation, and collagen and α-smooth muscle actin levels in CFs, while the knockdown of endogenous miR-22 decreased CFs numbers. Conclusions: Our findings demonstrate that miR-22 accelerates cardiac fibrosis through the miR-22-Cav3-PKCε pathway, which, therefore, may represent a new therapeutic target for treatment of excessive fibrosis-associated cardiac diseases.