Long-term soluble Abeta1-40 activates CaM kinase II in organotypic hippocampal cultures.

Recent findings suggested a role for soluble amyloid-beta (Abeta) peptides in Alzheimer's disease associated cognitive decline. We investigated the action of soluble, monomeric Abeta(1-40) on CaM kinase II, a kinase involved in neuroplasticity and cognition. We treated organotypic hippocampal cultures short-term (up to 4h) and long-term (5 days) with Abeta(1-40) (1nM-5microM).

Alpha2beta1 and alphaVbeta1 integrin signaling pathways mediate amyloid-beta-induced neurotoxicity.

Pathological hallmarks of Alzheimer's disease are the presence of extracellular amyloid plaques, intracellular neurofibrillary tangles, and neurodegeneration. The principal component of amyloid plaques is the amyloid-beta peptide (Abeta). Accumulating evidence indicates that Abeta may play a causal role in Alzheimer's disease.

Astrocyte- and hepatocyte-specific expression of genes from the distal serpin subcluster at 14q32.1 associates with tissue-specific chromatin structures.

The distal serpin subcluster contains genes encoding alpha1-antichymotrypsin (ACT), protein C inhibitor (PCI), kallistatin (KAL) and the KAL-like protein, which are expressed in hepatocytes, but only the act gene is expressed in astrocytes. We show here that the tissue-specific expression of these genes associates with astrocyte- and hepatocyte-specific chromatin structures. In hepatocytes, we identified 12 Dnase I-hypersensitive sites (DHSs) that were distributed throughout the entire subcluster, with the promoters of expressed genes accessible to restriction enzyme digestion.

Nucleation-dependent polymerization is an essential component of amyloid-mediated neuronal cell death.

Accumulating evidence suggests that amyloid protein aggregation is pathogenic in many diseases, including Alzheimer's disease. However, the mechanisms by which protein aggregation mediates cellular dysfunction and overt cell death are unknown. Recent reports have focused on the potential role of amyloid oligomers or protofibrils as a neurotoxic form of amyloid-beta (Abeta) and related amyloid aggregates.

Duration of alpha 1-antichymotrypsin gene activation by interleukin-1 is determined by efficiency of inhibitor of nuclear factor kappa B alpha resynthesis in primary human astrocytes.

Expression of alpha1antichymotrypsin (ACT) is significantly activated by interleukin-1 (IL-1) in human astrocytes; however, it is barely affected by IL-1 in hepatocytes. This tissue-specific regulation depends upon an enhancer that contains both nuclear factor kappaB (NF-kappaB) and activating protein 1 (AP-1) elements, and is also observed for an NF-kappaB reporter but not for an AP-1 reporter. We found efficient activation of NF-kappaB binding in both cell types; however, this binding was persistent in glial cells and only transient in hepatocytes.

Selective vulnerability of dentate granule cells prior to amyloid deposition in PDAPP mice: digital morphometric analyses.

Increasing evidence from mouse models of Alzheimer's disease shows that overexpression of a mutant form of the amyloid precursor protein (APP) and its product, beta-amyloid peptide, initiate pathological changes before amyloid deposition. To evaluate the cytological basis for one of these early changes, namely reduced volume of the dentate gyrus (DG), we have used high-throughput diOlistic cell loading and 3D neuronal reconstruction to investigate potential dendritic pathology of granule cells (GCs) in 90-day-old PDAPP mice. Labeled GCs from fixed hippocampal slices were selected randomly and imaged digitally by using confocal laser-scanning microscopy.

Amyloid deposition in the hippocampus and entorhinal cortex: quantitative analysis of a transgenic mouse model.

Various transgenic mouse models of Alzheimer's disease (AD) have been developed that overexpress mutant forms of amyloid precursor protein in an effort to elucidate more fully the potential role of beta-amyloid (A beta) in the etiopathogenesis of the disease. The present study represents the first complete 3D reconstruction of A beta in the hippocampus and entorhinal cortex of PDAPP transgenic mice. A beta deposits were detected by immunostaining and thioflavin fluorescence, and quantified by using high-throughput digital image acquisition and analysis.

Mechanism of plasminogen activator inhibitor-1 regulation by oncostatin M and interleukin-1 in human astrocytes.

Glial cells that produce and respond to various cytokines mediate inflammatory processes in the brain. Here, we show that oncostatin M (OSM) and interleukin-1 (IL-1) regulate the expression of plasminogen activator inhibitor-1 (PAI-1) and urokinase-type plasminogen activator (uPA) in human astrocytes. Using the PAI-1 reporter constructs we show that the -58 to -51 proximal element mediates activation by both cytokines.

Inflammatory repertoire of Alzheimer's disease and nondemented elderly microglia in vitro.

We have previously developed and characterized isolated microglia and astrocyte cultures from rapid (<4 h) brain autopsies of Alzheimer's disease (AD) and nondemented elderly control (ND) patients. In the present study, we evaluate the inflammatory repertoire of AD and ND microglia cultured from white matter (corpus callosum) and gray matter (superior frontal gyrus) with respect to three major proinflammatory cytokines, three chemokines, a classical pathway complement component, a scavenger cell growth factor, and a reactive nitrogen intermediate. Significant, dose-dependent increases in the production of pro-interleukin-1beta (pro-IL-1beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory peptide-1alpha (MIP-1alpha), IL-8, and macrophage colony-stimulating factor (M-CSF) were observed after exposure to pre-aggregated amyloid beta peptide (1-42) (Abeta1-42).

Tissue plasminogen activator requires plasminogen to modulate amyloid-beta neurotoxicity and deposition.

Tissue plasminogen (plgn) activator (tPA) modulates neuronal death in models of stroke, excitotoxicity, and oxidative stress. Amyloid-beta (Abeta) appears central to Alzheimer's disease and is neurotoxic to neurons in vitro. Here, we evaluate tPA effects on Abeta toxicity.

Mechanism of interleukin-1- and tumor necrosis factor alpha-dependent regulation of the alpha 1-antichymotrypsin gene in human astrocytes.

The expression of alpha(1)-antichymotrypsin (ACT) is significantly enhanced in affected brain regions in Alzheimer's disease. This serine proteinase inhibitor specifically colocalizes with filamentous beta-amyloid deposits and recently has been shown to influence both formation and destabilization of beta-amyloid fibrils. In the brain, ACT is expressed in astrocytes, and interleukin-1 (IL-1), tumor necrosis factor alpha (TNF), oncostatin M (OSM), and IL-6/soluble IL-6 receptor complexes control synthesis of this inhibitor.

The oligomerization of amyloid beta-protein begins intracellularly in cells derived from human brain.

The progressive aggregation and deposition of amyloid beta-protein (Abeta) in brain regions subserving memory and cognition is an early and invariant feature of Alzheimer's disease, the most common cause of cognitive failure in aged humans. Inhibiting Abeta aggregation is therapeutically attractive because this process is believed to be an exclusively pathological event. Whereas many studies have examined the aggregation of synthetic Abeta peptides under nonphysiological conditions and concentrations, we have detected and characterized the oligomerization of naturally secreted Abeta at nanomolar levels in cultures of APP-expressing CHO cells [Podlisny, M.

Inflammation and Alzheimer's disease.

Inflammation clearly occurs in pathologically vulnerable regions of the Alzheimer's disease (AD) brain, and it does so with the full complexity of local peripheral inflammatory responses. In the periphery, degenerating tissue and the deposition of highly insoluble abnormal materials are classical stimulants of inflammation. Likewise, in the AD brain damaged neurons and neurites and highly insoluble amyloid beta peptide deposits and neurofibrillary tangles provide obvious stimuli for inflammation.

The plasmin system is induced by and degrades amyloid-beta aggregates.

Amyloid-beta (Abeta) appears critical to Alzheimer's disease. To clarify possible mechanisms of Abeta action, we have quantified Abeta-induced gene expression in vitro by using Abeta-treated primary cortical neuronal cultures and in vivo by using mice transgenic for the Abeta precursor (AbetaP). Here, we report that aggregated, but not nonaggregated, Abeta increases the level of the mRNAs encoding tissue plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA).

c-Jun contributes to amyloid beta-induced neuronal apoptosis but is not necessary for amyloid beta-induced c-jun induction.

The role of gene expression in neuronal apoptosis may be cell- and apoptotic stimulus-specific. Previously, we and others showed that amyloid beta (Abeta)-induced neuronal apoptosis is accompanied by c-jun induction. Moreover, c-Jun contributes to neuronal death in several apoptosis paradigms involving survival factor withdrawal.

Soluble amyloid beta peptide concentration as a predictor of synaptic change in Alzheimer's disease.

We have characterized amyloid beta peptide (Abeta) concentration, Abeta deposition, paired helical filament formation, cerebrovascular amyloid angiopathy, apolipoprotein E (ApoE) allotype, and synaptophysin concentration in entorhinal cortex and superior frontal gyrus of normal elderly control (ND) patients, Alzheimer's disease (AD) patients, and high pathology control (HPC) patients who meet pathological criteria for AD but show no synapse loss or overt antemortem symptoms of dementia. The measures of Abeta deposition, Abeta-immunoreactive plaques with and without cores, thioflavin histofluorescent plaques, and concentrations of insoluble Abeta, failed to distinguish HPC from AD patients and were poor correlates of synaptic change. By contrast, concentrations of soluble Abeta clearly distinguished HPC from AD patients and were a strong inverse correlate of synapse loss.

Human amylin induces "apoptotic" pattern of gene expression concomitant with cortical neuronal apoptosis.

Amylin forms large beta-pleated neurotoxic oligomers but shows only 38% sequence similarity to A beta. As patterns of gene expression during neuronal apoptosis appear stimulus and cell type specific, we compared the pattern of amylin-induced gene expression in rat cortical neurons with that shown previously to be induced by A beta in order to evaluate whether these two peptides with different primary but similar secondary structure induce apoptosis similarly. Morphologic and quantitative measures of cell death show widespread apoptotic death after amylin treatment.

Oncostatin M and the interleukin-6 and soluble interleukin-6 receptor complex regulate alpha1-antichymotrypsin expression in human cortical astrocytes.

alpha1-Antichymotrypsin (ACT) is an acute phase protein expressed in the brain which specifically colocalizes with amyloid-beta during Alzheimer's disease. We analyzed ACT synthesis in cultured human cortical astrocytes in response to various cytokines and growth factors. Oncostatin M (OSM) and interleukin (IL)-1beta were potent stimulators of ACT mRNA expression, whereas tumor necrosis factor-alpha had modest activity, and IL-6 and leukemia inhibitory factor (LIF) were ineffective.

Aggregated amyloid-beta protein induces cortical neuronal apoptosis and concomitant "apoptotic" pattern of gene induction.

To gain a molecular understanding of neuronal responses to amyloid-beta peptide (Abeta), we have analyzed the effects of Abeta treatment on neuronal gene expression in vitro by quantitative reverse transcription-PCR and in situ hybridization. Treatment of cultured rat cortical neurons with Abeta1-40 results in a widespread apoptotic neuronal death. Associated with death is an induction of several members of the immediate early gene family.

Increased activity-regulating and neuroprotective efficacy of alpha-secretase-derived secreted amyloid precursor protein conferred by a C-terminal heparin-binding domain.

Proteolytic cleavage of beta-amyloid precursor protein (beta APP) by alpha-secretase results in release of one secreted form (sAPP) of APP (sAPP alpha), whereas cleavage by beta-secretase releases a C-terminally truncated sAPP (sAPP beta) plus amyloid beta-peptide (A beta). beta APP mutations linked to some inherited forms of Alzheimer's disease may alter its processing such that levels of sAPP alpha are reduced and levels of sAPP beta increased. sAPP alpha s may play important roles in neuronal plasticity and survival, whereas A beta can be neurotoxic.

Amyloid beta-mediated oxidative and metabolic stress in rat cortical neurons: no direct evidence for a role for H2O2 generation.

H2O2 and free radical-mediated oxidative stresses have been implicated in mediating amyloid beta (1-40) [A beta (1-40)] neurotoxicity to cultured neurons. In this study, we confirm that addition of the H2O2-scavenging enzyme catalase protects neurons in culture against A beta-mediated toxicity; however, it does so by a mechanism that does not involve its ability to scavenge H2O2. A beta-mediated elevation in intracellular H2O2 production is suppressed by addition of a potent H2O2 scavenger without any significant neuroprotection.

Amyloid beta peptide potentiates cytokine secretion by interleukin-1 beta-activated human astrocytoma cells.

Neurodegenerative processes in Alzheimer disease (AD) are thought to be driven in part by the deposition of amyloid beta (A beta), a 39- to 43-amino acid peptide product resulting from an alternative cleavage of amyloid precursor protein. Recent descriptions of in vitro neurotoxic effects of A beta support this hypothesis and suggest toxicity might be mediated by A beta-induced neuronal calcium disregulation. In addition, it has been reported that "aging" A beta results in increased toxic potency due to peptide aggregation and formation of a beta-sheet secondary structure.

Secreted forms of beta-amyloid precursor protein protect against ischemic brain injury.

The beta-amyloid precursor protein (beta APP) is the source of the amyloid beta-peptide that accumulates in the brain in Alzheimer's disease. A major processing pathway for beta APP involves an enzymatic cleavage within the amyloid beta-peptide sequence that liberates secreted forms of beta APP (APPss) into the extracellular milieu. We now report that postischemic administration of these APPss intracerebroventricularly protects neurons in the CA1 region of rat hippocampus against ischemic injury.