humanin and Mitochondrial-Diseases

What is the central question of this study? Myocardial ischaemia-reperfusion (I/R) injury causes interference in the systemic circulation and damages not only the heart but also several vital organs, including the brain. Recently, a novel peptide called humanin has been shown to exert potent neuroprotective effects. However, the effect of humanin on the brain during cardiac I/R injury has not yet been investigated. What is the main finding and its importance? The I/R injury caused blood-brain barrier breakdown, increased brain oxidative stress and resulted in mitochondrial dysfunction. Only the humanin treatment before ischaemia attenuated brain mitochondrial dysfunction, but it did not prevent blood-brain barrier breakdown or brain oxidative stress. Humanin treatment during ischaemia and in the reperfusion period provided no neuroprotection. These findings indicate that humanin exerted neuroprotection during cardiac I/R injury via improved brain mitochondrial function. Myocardial ischaemia-reperfusion (I/R) injury causes interference in the systemic circulation and damages not only the heart but also several vital organs, including the brain. Nevertheless, limited information is available regarding the effect of cardiac I/R injury on the brain, including blood-brain barrier (BBB) breakdown, brain oxidative stress and mitochondrial function. Recently, a novel peptide called humanin has been shown to exert potent neuroprotective effects. However, the effect of humanin on the brain during cardiac I/R injury has not yet been investigated. Forty-two male Wistar rats were divided into the following two groups: an I/R group, which was subjected to a 30 min left anterior descending coronary artery occlusion followed by 120 min reperfusion (I/R group; n = 36); and a sham group (n = 6). The I/R group was divided into six subgroups. Each subgroup was given either vehicle or humanin analogue (84 μg kg(-1) , i.v.) at three different time points, namely before ischaemia, during ischaemia or at the onset of reperfusion. At the end of the experimental protocol, animals were killed and the brains removed for determination of mitochondrial function, oxidative stress and Western blot analyses. The I/R injury caused BBB breakdown, increased brain oxidative stress and resulted in mitochondrial dysfunction. Only the humanin treatment before ischaemia attenuated brain mitochondrial dysfunction, but it did not prevent BBB breakdown or brain oxidative stress. Humanin treatment d

Topics: Animals; Blood-Brain Barrier; Brain; Coronary Artery Disease; Coronary Vessels; Disease Models, Animal; Heart; Intracellular Signaling Peptides and Proteins; Male; Mitochondria; Mitochondrial Diseases; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Oxidative Stress; Rats; Rats, Wistar

Myocardial reperfusion via the re-canalization of occluded coronary arteries is gold standard for the treatment of acute myocardial infarction. However, reperfusion itself can cause myocardial damage due to increased reactive oxygen species (ROS) production, a process known as ischemia/reperfusion (I/R) injury. Cardiac mitochondria are the major organelle of ROS production in the heart. Cardiac mitochondrial dysfunction caused by an increased ROS production can increase cardiac arrhythmia incidence, myocardial infarct size, and cardiac dysfunction. Thus, preservation of cardiac mitochondrial function is a promising pharmacological approach to reduce cardiac I/R injury. Humanin (HN), a newly discovered 24-amino acid polypeptide, has been shown to exert antioxidative stress and antiapoptotic effects. Although the cardioprotective effects of HN against I/R injury has been reported, the effect of HN on cardiac mitochondrial function has not yet been investigated. Thus, we tested the hypothesis that HN exerts its cardioprotective effects against I/R injury through the attenuation of cardiac mitochondrial dysfunction.. I/R protocol was carried out using a 30-minutes occlusion of a left anterior descending coronary artery followed by a 120-minutes of reperfusion. The plasma HN level, infarct size, arrhythmia incidence, left ventricular function, and cardiac mitochondrial function were determined.. Endogenous HN level before I/R injury showed no difference between groups, but was markedly decreased after I/R injury. HN analogue pretreatment decreased arrhythmia incidence and infarct size, improved cardiac mitochondrial function, and attenuated cardiac dysfunction.. Humanin analogue pretreatment exerted cardioprotective effects against I/R injury through the attenuation of cardiac mitochondrial dysfunction.

Topics: Animals; Arrhythmias, Cardiac; Cardiotonic Agents; Disease Models, Animal; Drug Administration Schedule; Intracellular Signaling Peptides and Proteins; Male; Mitochondria, Heart; Mitochondrial Diseases; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Oxidative Stress; Rats, Wistar; Reactive Oxygen Species; Time Factors; Ventricular Function, Left

Mitochondrial dysfunction is a hallmark of beta-amyloid (Abeta)-induced neuronal toxicity in Alzheimer's disease (AD), and is considered as an early event in AD pathology. Humanin (HN) and its derivative, [Gly14]-Humanin (HNG), are known for their ability to suppress neuronal death induced by AD-related insults in vitro and in vivo. In the present study, we investigated the neuroprotective effects of HNG on Abeta(25-35)-induced toxicity and its potential mechanisms in PC12 cells. Exposure of PC12 cells to 25 microM Abeta(25-35) caused significant viability loss and cell apoptosis. In addition, decreased mitochondrial membrane potential and increased cytochrome c releases from mitochondria were also observed after Abeta(25-35) exposure. All these effects induced by Abeta(25-35) were markedly reversed by HNG. Pretreatment with 100 nM HNG 6h prior to Abeta(25-35) exposure significantly elevated cell viability, reduced Abeta(25-35)-induced cell apoptosis, stabilized mitochondrial membrane potential, and blocked cytochrome c release from mitochondria. Furthermore, HNG also ameliorated the Abeta(25-35)-induced Bcl-2/Bax ratio reduction and decreased caspase-3 activity in PC12 cells. These results demonstrate that HNG could attenuate Abeta(25-35)-induced PC12 cell injury and apoptosis by preventing mitochondrial dysfunction. Furthermore, these data suggest that mitochondria are involved in the protective effect of HNG against Abeta(25-35).

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Apoptosis; Apoptosis Regulatory Proteins; Cell Survival; Cytoprotection; Energy Metabolism; Intracellular Signaling Peptides and Proteins; Membrane Potentials; Metabolic Networks and Pathways; Mitochondria; Mitochondrial Diseases; Nerve Degeneration; Neuroprotective Agents; PC12 Cells; Peptide Fragments; Rats

To define the pathogenesis of pigmented villonodular synovitis (PVNS), by searching for highly expressed genes in primary synovial cells from patients with PVNS.. A combination of subtraction cloning and Southern colony hybridisation was used to detect highly expressed genes in PVNS in comparison with rheumatoid synovial cells. Northern hybridisation was performed to confirm the differential expression of the humanin gene in PVNS. Expression of the humanin peptide was analysed by western blotting and immunohistochemistry. Electron microscopic immunohistochemistry was performed to investigate the distribution of this peptide within the cell.. 68 highly expressed genes were identified in PVNS. Humanin genes were strongly expressed in diffuse-type PVNS, but were barely detected in nodular-type PVNS, rheumatoid arthritis, or osteoarthritis. Humanin peptide was identified in synovium from diffuse-type PVNS, and most of the positive cells were distributed in the deep layer of the synovial tissue. Double staining with anti-humanin and anti-heat shock protein 60 showed that humanin was expressed mainly in mitochondria. Electron microscopy disclosed immunolocalisation of this peptide, predominantly around dense iron deposits within the siderosome.. Increased expression of the humanin peptide in mitochondria and siderosomes is characteristic of synovial cells from diffuse-type PVNS. Humanin is an anti-apoptotic peptide which is encoded in the mitochondrial genome. Present findings suggest that mitochondrial dysfunction may be the principal factor in pathogenesis of diffuse-type PVNS and that humanin peptide may play a part in the neoplastic process in this form of PVNS.

Topics: Arthritis, Rheumatoid; Blotting, Northern; Blotting, Western; Gene Expression; Humans; Intracellular Signaling Peptides and Proteins; Microscopy, Electron; Mitochondria; Mitochondrial Diseases; Osteoarthritis; Proteins; Reverse Transcriptase Polymerase Chain Reaction; Synovial Membrane; Synovitis, Pigmented Villonodular