Dataset Information

Sirt3 Ameliorates Oxidative Stress and Mitochondrial Dysfunction After Intracerebral Hemorrhage in Diabetic Rats.

ABSTRACT: Aim: Sirtuin3 (sirt3) plays a pivotal role in improving oxidative stress and mitochondrial dysfunction which directly induced neuronal apoptosis after intracerebral hemorrhage (ICH). Reactive oxygen species (ROS) is also a critical activator in triggering NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasomes activation which can regulate inflammatory responses in brain. Moreover, hyperglycemia can aggravate the ICH-induced damage. Hence, this study was designed to investigate the mechanisms of neuroprotection of sirt3 in hyperglycemic ICH. Methods: ICH model was established by autologous blood injection. Hyperglycemia was induced by intraperitoneal injection with streptozotocin. Honokiol (HKL, a pharmacological agonist of sirt3) was injected intraperitoneally at doses of 2.5, 5, or 10 mg/kg. Sirt3 small interfering RNA transfection was implemented through intracerebroventricular injection. The expression of sirt3 and its downstream signaling molecules were detected using Western blotting or immunofluorescence staining. Morphological changes of mitochondria were detected by electron microscopy. SH-SY5Y cells were incubated with 10 ?M oxyhemoglobin for 48 h to establish an in vitro ICH model, and then JC-1 staining was used to determine mitochondrial membrane potential (??m). Results: Hyperglycemia could suppress sirt3 expression after ICH when compared with non-diabetic rats. Sirt3 protein expression was decreased to the minimum at 24 h in perihematoma tissues. Electron microscope analysis indicated that hyperglycemic ICH induced extensive mitochondrial vacuolization. HKL attenuated ROS accumulation, adenosine triphosphate reduction, and ??m through Sirt3-superoxide dismutase 2 (SOD2) and Sirt3-NRF1-TFAM pathway. Sirt3 knockdown could exacerbate the neuronal apoptosis and reverse the positive effects of HKL. Sirt3 activation could decrease NLRP3 and interleukin-1? levels through deacetylating SOD2 and scavenging ROS. Conclusion: HKL protects against hyperglycemic ICH-induced neuronal injury via a sirt3-dependent manner.

SUBMITTER: Zheng J

PROVIDER: S-EPMC6018086 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Sirt3 Ameliorates Oxidative Stress and Mitochondrial Dysfunction After Intracerebral Hemorrhage in Diabetic Rats.

Zheng Jingwei J Shi Ligen L Liang Feng F Xu Weilin W Li Tao T Gao Liansheng L Sun Zeyu Z Yu Jun J Zhang Jianmin J

Frontiers in neuroscience 20180619

<b>Aim:</b> Sirtuin3 (sirt3) plays a pivotal role in improving oxidative stress and mitochondrial dysfunction which directly induced neuronal apoptosis after intracerebral hemorrhage (ICH). Reactive oxygen species (ROS) is also a critical activator in triggering NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasomes activation which can regulate inflammatory responses in brain. Moreover, hyperglycemia can aggravate the ICH-induced damage. Hence, this study was designed to investi ...[more]

PMID: 29970985

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Project description:Intracerebral hemorrhage is often accompanied by oxidative stress induced by reactive oxygen species, which causes abnormal mitochondrial function and secondary reactive oxygen species generation. This creates a vicious cycle leading to reactive oxygen species accumulation, resulting in progression of the pathological process. Therefore, breaking the cycle to inhibit reactive oxygen species accumulation is critical for reducing neuronal death after intracerebral hemorrhage. Our previous study found that increased expression of nicotinamide adenine dinucleotide phosphate oxidase 4 (NADPH oxidase 4, NOX4) led to neuronal apoptosis and damage to the blood-brain barrier after intracerebral hemorrhage. The purpose of this study was to investigate the role of NOX4 in the circle involving the neuronal tolerance to oxidative stress, mitochondrial reactive oxygen species and modes of neuronal death other than apoptosis after intracerebral hemorrhage. We found that NOX4 knockdown by adeno-associated virus (AAV-NOX4) in rats enhanced neuronal tolerance to oxidative stress, enabling them to better resist the oxidative stress caused by intracerebral hemorrhage. Knockdown of NOX4 also reduced the production of reactive oxygen species in the mitochondria, relieved mitochondrial damage, prevented secondary reactive oxygen species accumulation, reduced neuronal pyroptosis and contributed to relieving secondary brain injury after intracerebral hemorrhage in rats. Finally, we used a mitochondria-targeted superoxide dismutase mimetic to explore the relationship between reactive oxygen species and NOX4. The mitochondria-targeted superoxide dismutase mimetic inhibited the expression of NOX4 and neuronal pyroptosis, which is similar to the effect of AAV-NOX4. This indicates that NOX4 is likely to be an important target for inhibiting mitochondrial reactive oxygen species production, and NOX4 inhibitors can be used to alleviate oxidative stress response induced by intracerebral hemorrhage.

Project description:RationaleHypertension represents a major risk factor for stroke, myocardial infarction, and heart failure and affects 30% of the adult population. Mitochondrial dysfunction contributes to hypertension, but specific mechanisms are unclear. The mitochondrial deacetylase Sirt3 (Sirtuin 3) is critical in the regulation of metabolic and antioxidant functions which are associated with hypertension, and cardiovascular disease risk factors diminish Sirt3 level.ObjectiveWe hypothesized that reduced Sirt3 expression contributes to vascular dysfunction in hypertension, but increased Sirt3 protects vascular function and decreases hypertension.Methods and resultsTo test the therapeutic potential of targeting Sirt3 expression, we developed new transgenic mice with global Sirt3OX (Sirt3 overexpression), which protects from endothelial dysfunction, vascular oxidative stress, and hypertrophy and attenuates Ang II (angiotensin II) and deoxycorticosterone acetate-salt induced hypertension. Global Sirt3 depletion in Sirt3-/- mice results in oxidative stress due to hyperacetylation of mitochondrial superoxide dismutase (SOD2), increases HIF1α (hypoxia-inducible factor-1), reduces endothelial cadherin, stimulates vascular hypertrophy, increases vascular permeability and vascular inflammation (p65, caspase 1, VCAM [vascular cell adhesion molecule-1], ICAM [intercellular adhesion molecule-1], and MCP1 [monocyte chemoattractant protein 1]), increases inflammatory cell infiltration in the kidney, reduces telomerase expression, and accelerates vascular senescence and age-dependent hypertension; conversely, increased Sirt3 expression in Sirt3OX mice prevents these deleterious effects. The clinical relevance of Sirt3 depletion was confirmed in arterioles from human mediastinal fat in patients with essential hypertension showing a 40% decrease in vascular Sirt3, coupled with Sirt3-dependent 3-fold increases in SOD2 acetylation, NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) activity, VCAM, ICAM, and MCP1 levels in hypertensive subjects compared with normotensive subjects.ConclusionsWe suggest that Sirt3 depletion in hypertension promotes endothelial dysfunction, vascular hypertrophy, vascular inflammation, and end-organ damage. Our data support a therapeutic potential of targeting Sirt3 expression in vascular dysfunction and hypertension.

Dataset Information

Sirt3 Ameliorates Oxidative Stress and Mitochondrial Dysfunction After Intracerebral Hemorrhage in Diabetic Rats.

Publications

Sirt3 Ameliorates Oxidative Stress and Mitochondrial Dysfunction After Intracerebral Hemorrhage in Diabetic Rats.

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