Search

Mitochondrial dysfunction is an early pathological feature of Alzheimer disease and plays a crucial role in the development and progression of Alzheimer's disease. Strategies to rescue mitochondrial function and cognition remain to be explored. Cyclophilin D (CypD), the peptidylprolyl isomerase F (PPIase), is a key component in opening the mitochondrial membrane permeability transition pore, leading to mitochondrial dysfunction and cell death. Blocking membrane permeability transition pore opening by inhibiting CypD activity is a promising therapeutic approach for Alzheimer's disease. However, there is currently no effective CypD inhibitor for Alzheimer's disease, with previous candidates demonstrating high toxicity, poor ability to cross the blood–brain barrier, compromised biocompatibility and low selectivity. Here, we report a new class of non-toxic and biocompatible CypD inhibitor, ebselen, using a conventional PPIase assay to screen a library of ∼2000 FDA-approved drugs with crystallographic analysis of the CypD-ebselen crystal structure (PDB code: 8EJX). More importantly, we assessed the effects of genetic and pharmacological blockade of CypD on Alzheimer's disease mitochondrial and glycolytic bioenergetics in Alzheimer's disease-derived mitochondrial cybrid cells, an ex vivo human sporadic Alzheimer's disease mitochondrial model, and on synaptic function, inflammatory response and learning and memory in Alzheimer's disease mouse models. Inhibition of CypD by ebselen protects against sporadic Alzheimer's disease- and amyloid-β-induced mitochondrial and glycolytic perturbation, synaptic and cognitive dysfunction, together with suppressing neuroinflammation in the brain of Alzheimer's disease mouse models, which is linked to CypD-related membrane permeability transition pore formation. Thus, CypD inhibitors have the potential to slow the progression of neurodegenerative diseases, including Alzheimer's disease, by boosting mitochondrial bioenergetics and improving synaptic and cognitive function. [ABSTRACT FROM AUTHOR]

Protein kinase C-[beta]II (PKC[beta]II) is an important modulator of cellular stress responses. To test the hypothesis that PKC[beta]II modulates the response to myocardial ischemia-reperfusion (I/R) injury, we subjected mice to occlusion and reperfusion of the left anterior descending coronary artery. Homozygous PKC[beta]-null ([PKC[beta].sup.-/-]) and wildtype mice fed the PKC[beta] inhibitor ruboxistaurin displayed significantly decreased infarct size and enhanced recovery of left ventricular (LV) function and reduced markers of cellular necrosis and serum creatine phosphokinase and lactate dehydrogenase levels compared with wild-type or vehicle-treated animals after 30 rain of ischemia followed by 48 h of reperfusion. Our studies revealed that membrane translocation of PKC[beta]II in LV tissue was sustained after I/R and that gene deletion or pharmacological blockade of PKC[beta] protected ischemic myocardium. Homozygous deletion of PKC[beta] significantly diminished phosphorylation of c-Jun N[H.sub.2]-terminal mitogen-activated protein kinase and expression of activated caspase-3 in LV tissue of mice subjected to I/R. These data implicate PKC[beta] in I/R-mediated myocardial injury, at least in part via phosphorylation of JNK, and suggest that blockade of PKC[beta] may represent a potent strategy to protect the vulnerable myocardium. myocardial ischemia; JNK; caspase-3

The receptor for advanced glycation end-products (RAGE) has been implicated in the pathogenesis of ischemia-reperfusion (I/R) injury in the isolated perfused heart. To test the hypothesis that RAGE-dependent mechanisms modulated responses to I/R in a murine model of transient occlusion and reperfusion of the left anterior descending coronary artery (LAD), we subjected male homozygous [RAGE.sup.-/-] mice and their wild-type age-matched littermates to 30 min of occlusion of the LAD followed by reperfusion. At 48 h of reperfusion, hematoxylin and eosin staining revealed significantly larger infarct size in wild-type versus [RAGE.sup.-/-] mice. Contractile function, as evaluated by echocardiography 48 h after reperfusion, revealed that fractional shortening was significantly higher in [RAGE.sup.-/-] versus wild-type mice. Plasma levels of creatine kinase were markedly decreased in [RAGE.sup.-/-] versus wild-type animals. Integral to the impact of RAGE deletion on diminished myocardial damage after infarction was significantly decreased apoptosis in the heart, as assessed by TUNEL staining, release of cytochrome c, and caspase-3 activity. Experiments investigating the impact of RAGE on early signaling pathways influencing myocardial ischemic injury revealed attenuation of JNK and STAT5 phosphorylation in [RAGE.sup.-/-] mouse hearts versus robust activation observed in wild-type mice upon ischemia and reperfusion. Solidifying the link to RAGE, these experiments revealed that infarction stimulated the rapid production of advanced glycation endproducts in the heart. Thus, we tested the effect of ligand decoy soluble RAGE (sRAGE). Administration of sRAGE protected the myocardium from ischemic damage, similar to the effects observed in [RAGE.sup.-/-] mouse hearts. Taken together, these data implicate RAGE and its ligands in the pathogenesis of I/R injury and identify JNK and STAT signal transduction as central downstream effector pathways of the ligand-RAGE axis in the heart subjected to I/R injury. receptor for advanced glycation end-products; glycation end-products; myocardial infarction; left anterior descending coronary artery

Endothelial dysfunction is a key triggering event in atherosclerosis. Following the entry of lipoproteins into the vessel wall, their rapid modification results in the generation of advanced glycation endproduct epitopes and subsequent infiltration of inflammatory cells. These inflammatory cells release receptor for advanced glycation endproduct (RAGE) ligands, specifically S100/calgranulins and high-mobility group box 1, which sustain vascular injury. Here, we demonstrate critical roles for RAGE and its ligands in vascular inflammation, endothelial dysfunction, and atherosclerotic plaque development in a mouse model of atherosclerosis, apoE-/- mice. Experiments in primary aortic endothelial cells isolated from mice and in cultured human aortic endothelial cells revealed the central role of JNK signaling in transducing the impact of RAGE ligands on inflammation. These data highlight unifying mechanisms whereby endothelial RAGE and its ligands mediate vascular and inflammatory stresses that culminate in atherosclerosis in the vulnerable vessel wall., Introduction The metabolic and biochemical milieu generated upon entry of lipid into the vessel wall drives the generation of ligands of the receptor for advanced glycation endproduct (RAGE), including advanced [...]

Multiple sclerosis (MS) is a devastating neuroinflammatory disorder of the central nervous system (CNS) in which T cells that are reactive with major components of myelin sheaths have a central role. The receptor for advanced glycation end products (RAGE) is present on T cells, mononuclear phagocytes and endothelium. Its pro-inflammatory ligands, S100-calgranulins, are upregulated in MS and in the related rodent model, experimental autoimmune encephalomyelitis (EAE). Blockade of RAGE suppressed EAE when disease was induced by myelin basic protein (MBP) peptide or encephalitogenic T cells, or when EAE occurred spontaneously in T-cell receptor (TCR)-transgenic mice devoid of endogenous TCR-[alpha] and TCR-[beta] chains. Inhibition of RAGE markedly decreased infiltration of the CNS by immune and inflammatory cells. Transgenic mice with targeted overexpression of dominant-negative RAGE in CD4[sup.+] T cells were resistant to MBP-induced EAE. These data reinforce the importance of RAGE-ligand interactions in modulating properties of CD4[sup.+] T cells that infiltrate the CNS., Author(s): Shirley ShiDu Yan (corresponding author) [1]; Zhi-Ying Wu [1, 2]; Hui Ping Zhang [1]; Glaucia Furtado [3]; Xi Chen [4]; Shi Fang Yan [1]; Ann Marie Schmidt [1]; Chris [...]

Carbon monoxide (CO) can arrest cellular respiration, but paradoxically, it is synthesized endogenously by heme oxygenase type 1 (Ho-1) in response to ischemic stress. Ho-1-deficient (Hmox1[sup.-/-]) mice exhibited lethal ischemic lung injury, but were rescued from death by inhaled CO. CO drove ischemic protection by activating soluble guanylate cyclase and thereby suppressed hypoxic induction of the gene encoding plasminogen activator inhibitor-1 (PAI-1) in mononuclear phagocytes, which reduced accrual of microvascular fibrin. CO-mediated ischemic protection observed in wild-type mice was lost in mice null for the gene encoding PAI-1 (Serpine1). These data establish a fundamental link between CO and prevention of ischemic injury based on the ability of CO to derepress the fibrinolytic axis. These data also point to a potential therapeutic use for inhaled CO., Author(s): Tomoyuki Fujita [1]; Koichi Toda [1]; Ann Karimova [1]; Shi-Fang Yan [1]; Yoshifumi Naka [1]; Shaw-Fang Yet [2]; David J. Pinsky (corresponding author) [1] Carbon monoxide (CO), once thought [...]

Activation of the zinc-finger transcription factor early growth response (Egr)-1, initially linked to developmental processes, is shown here to function as a master switch activated by ischemia to trigger expression of pivotal regulators of inflammation, coagulation and vascular hyperpermeability. Chemokine, adhesion receptor, procoagulant and permeability-related genes are coordinately upregulated by rapid ischemia-mediated activation of Egr-1. Deletion of the gene encoding Egr-1 strikingly diminished expression of these mediators of vascular injury in a murine model of lung ischemia/reperfusion, and enhanced animal survival and organ function. Rapid activation of Egr-1 in response to oxygen deprivation primes the vasculature for dysfunction manifest during reperfusion. These studies define a central and unifying role for Egr-1 activation in the pathogenesis of ischemic tissue damage., Author(s): Shi-Fang Yan (corresponding author) [1]; Tomoyuki Fujita [1]; Jiesheng Lu [1]; Kenji Okada [1]; Yu Shan Zou [1]; Nigel Mackman [4]; David J. Pinsky [3]; David M. Stern [1, [...]

In Alzheimer disease (AD), neurons are thought to be subjected to the deleterious cytotoxic effects of activated microglia. We demonstrate that binding of amyloid-beta peptide (A[Beta]) to neuronal Receptor for Advanced Glycation Endproduct (RAGE), a cell surface receptor for A[Beta], induces macrophage-colony stimulating factor (M-CSF) by an oxidant sensitive, nuclear factor [Kappa]B-dependent pathway. AD brain shows increased neuronal expression of M-CSF in proximity to A[Beta] deposits, and in cerebrospinal fluid from AD patients there was [approximately equal to]5-fold increased M-CSF antigen (P < 0.01), compared with age-matched controls. M-CSF released by A[Beta]-stimulated neurons interacts with its cognate receptor, c-fms, on microglia, thereby triggering chemotaxis, cell proliferation, increased expression of the macrophage scavenger receptor and apolipoprotein E, and enhanced survival of microglia exposed to A[Beta], consistent with pathologic findings in AD. These data delineate an inflammatory pathway triggered by engagement of A[Beta] on neuronal RAGE. We suggest that M-CSF, thus generated, contributes to the pathogenesis of AD, and that M-CSF in cerebrospinal fluid might provide a means for monitoring neuronal perturbation at an early stage in AD.