Publications by authors named "John X Chen"

Mitochondrial dysfunction and axonal degeneration are early pathological features of Alzheimer's disease (AD)-affected brains. The underlying mechanisms and strategies to rescue it have not been well elucidated. Here, we evaluated axonal mitochondrial transport and function in AD subject-derived mitochondria.

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Accumulation of amyloid-β (Aβ) in synaptic mitochondria is associated with mitochondrial and synaptic injury. The underlying mechanisms and strategies to eliminate Aβ and rescue mitochondrial and synaptic defects remain elusive. Presequence protease (PreP), a mitochondrial peptidasome, is a novel mitochondrial Aβ degrading enzyme.

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Diabetes is considered to be a risk factor in Alzheimer's disease (AD) pathogenesis. Although recent evidence indicates that diabetes exaggerates pathologic features of AD, the underlying mechanisms are not well understood. To determine whether mitochondrial perturbation is associated with the contribution of diabetes to AD progression, we characterized mouse models of streptozotocin (STZ)-induced type 1 diabetes and transgenic AD mouse models with diabetes.

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Mitochondrial dysfunction is an early pathological feature of Alzheimer's disease (AD). The underlying mechanisms and strategies to repair it remain unclear. Here, we demonstrate for the first time the direct consequences and potential mechanisms of mitochondrial functional defects associated with abnormal mitochondrial dynamics in AD.

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The coexistence of neuronal mitochondrial pathology and synaptic dysfunction is an early pathological feature of Alzheimer's disease (AD). Cyclophilin D (CypD), an integral part of mitochondrial permeability transition pore (mPTP), is involved in amyloid beta (Aβ)-instigated mitochondrial dysfunction. Blockade of CypD prevents Aβ-induced mitochondrial malfunction and the consequent cognitive impairments.

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Normal axonal mitochondrial transport and function is essential for the maintenance of synaptic function. Abnormal mitochondrial motility and mitochondrial dysfunction within axons are critical for amyloid β (Aβ)-induced synaptic stress and the loss of synapses relevant to the pathogenesis of Alzheimer's disease (AD). However, the mechanisms controlling axonal mitochondrial function and transport alterations in AD remain elusive.

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RAGE, a receptor for advanced glycation endproducts, is an immunoglobulin-like cell surface receptor that is often described as a pattern recognition receptor due to the structural heterogeneity of its ligand. RAGE is an important cellular cofactor for amyloid beta-peptide (Abeta)-mediated cellular perturbation relevant to the pathogenesis of Alzheimer's disease (AD). The interaction of RAGE with Abeta in neurons, microglia, and vascular cells accelerates and amplifies deleterious effects on neuronal and synaptic function.

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Accumulation of amyloid-β peptide (Aβ), the neurotoxic peptide implicated in the pathogenesis of Alzheimer's disease (AD), has been shown in brain mitochondria of AD patients and of AD transgenic mouse models. The presence of Aβ in mitochondria leads to free radical generation and neuronal stress. Recently, we identified the presequence protease, PreP, localized in the mitochondrial matrix in mammalian mitochondria as the novel mitochondrial Aβ-degrading enzyme.

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Mitochondrial dysfunction is an early feature of Alzheimer's disease (AD). Abnormalities in mitochondrial properties include impaired energy metabolism, defects in key respiratory enzyme activity/function, accumulation/generation of mitochondrial reactive oxygen species, and formation of membrane permeability transition pore. While the mechanisms underlying mitochondrial dysfunction remain incompletely understood, recent studies provide substantial evidence for the progressive accumulation of mitochondrial Abeta, which directly links to mitochondria-mediated toxicity.

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The immunity-related GTPase Irgm1, also called LRG-47, is known to regulate host resistance to intracellular pathogens through multiple mechanisms that include controlling the survival of T lymphocytes. Here, we address whether Irgm1 also plays a role in the pathogenesis of experimental autoimmune encephalitis (EAE). We find that Irgm1/LRG-47 is a significant factor in the progression of EAE and multiple sclerosis (MS).

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Microglia are critical for amyloid-beta peptide (Abeta)-mediated neuronal perturbation relevant to Alzheimer's disease (AD) pathogenesis. We demonstrate that overexpression of receptor for advanced glycation end products (RAGE) in imbroglio exaggerates neuroinflammation, as evidenced by increased proinflammatory mediator production, Abeta accumulation, impaired learning/memory, and neurotoxicity in an Abeta-rich environment. Transgenic (Tg) mice expressing human mutant APP (mAPP) in neurons and RAGE in microglia displayed enhanced IL-1beta and TNF-alpha production, increased infiltration of microglia and astrocytes, accumulation of Abeta, reduced acetylcholine esterase (AChE) activity, and accelerated deterioration of spatial learning/memory.

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Cyclophilin D (CypD, encoded by Ppif) is an integral part of the mitochondrial permeability transition pore, whose opening leads to cell death. Here we show that interaction of CypD with mitochondrial amyloid-beta protein (Abeta) potentiates mitochondrial, neuronal and synaptic stress. The CypD-deficient cortical mitochondria are resistant to Abeta- and Ca(2+)-induced mitochondrial swelling and permeability transition.

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Soluble amyloid-beta (Abeta) peptide is likely to play a key role during early stages of Alzheimer's disease (AD) by perturbing synaptic function and cognitive processes. Receptor for advanced glycation end products (RAGE) has been identified as a receptor involved in Abeta-induced neuronal dysfunction. We investigated the role of neuronal RAGE in Abeta-induced synaptic dysfunction in the entorhinal cortex, an area of the brain important in memory processes that is affected early in AD.

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Alzheimer patients have increased levels of both the 42 amyloid-beta-peptide (Abeta) and the amyloid binding alcohol dehydrogenase (ABAD), which is an intracellular binding site for Abeta. The overexpression of Abeta and ABAD in transgenic mice has shown that the binding of Abeta to ABAD results in amplified neuronal stress and impairment of learning and memory. From a proteomic analysis of the brains from these animals, we have identified for the first time that the protein endophilin I increases in Alzheimer diseased brain.

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Metabolic dysfunction is one of the early features in Alzheimer's disease (AD) affected brain. Amyloid-beta peptide (Abeta), a major peptide deposited in neuritic plaques, has been considered as an important initiating molecule in the pathogenesis of AD. However, the pathogenic role of Abeta remains to be determined.

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As an important molecule in the pathogenesis of Alzheimer's disease (AD), amyloid-beta (Abeta) interferes with multiple aspects of mitochondrial function, including energy metabolism failure, production of reactive oxygen species (ROS) and permeability transition pore formation. Recent studies have demonstrated that Abeta progressively accumulates within mitochondrial matrix, providing a direct link to mitochondrial toxicity. Abeta-binding alcohol dehydrogenase (ABAD) is localized to the mitochondrial matrix and binds to mitochondrial Abeta.

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Alzheimer's patients have increased levels of both the 42 beta amyloid-beta-peptide (Abeta) and amyloid binding alcohol dehydrogenase (ABAD) which is an intracellular binding site for Abeta. The over-expression of Abeta and ABAD in transgenic mice has shown that the binding of Abeta to ABAD results in exaggerating neuronal stress and impairment of learning and memory. From a proteomic analysis of the brains from these animals we identified that peroxiredoxin II levels increase in Alzheimer's diseased brain.

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