Disrupting beta-amyloid aggregation for Alzheimer disease treatment.

Alzheimer's disease is a devastating degenerative disorder for which there is no cure or effective treatment. Although the etiology of Alzheimer's disease is not fully understood, compelling evidence indicates that deposition of aggregates composed by a misfolded form of the amyloid beta peptide (Abeta) is the central event in the disease pathogenesis. Therefore, an attractive therapeutic strategy is to prevent or reverse Abeta misfolding and aggregation.

The intriguing prion disorders.

Prion diseases are among the most intriguing illnesses. Despite their rare incidence, they have captured enormous attention from the scientific community and general public. One of the most hotly debated issues in these diseases is the nature of the infectious material.

Inhibition of protein misfolding and aggregation by small rationally-designed peptides.

Several human diseases are associated with the presence of toxic fibrillar protein deposits. These diseases called protein misfolding disorders, are characterized by the accumulation of misfolded protein aggregates in diverse tissues. Strong evidence indicates that the conversion of a normal soluble protein into a beta-sheet-rich oligomeric structure and further fibrillar aggregation are the key events in the disease pathogenesis.

Presymptomatic detection of prions in blood.

Prions are thought to be the proteinaceous infectious agents responsible for transmissible spongiform encephalopathies (TSEs). PrP(Sc), the main component of the infectious agent, is also the only validated surrogate marker for the disease, and its sensitive detection is critical for minimizing the spread of the disease. We detected PrP(Sc) biochemically in the blood of hamsters infected with scrapie during most of the presymptomatic phase of the disease.

Puma and p53 play required roles in death evoked in a cellular model of Parkinson disease.

6-Hydroxydopamine (6-OHDA) is widely used in vivo and in vitro to mimic the selective neuronal degeneration that characterizes Parkinson disease (PD). To uncover candidate genes that may mediate neuron death in PD, we previously used SAGE to identify transcripts that are rapidly induced by 6-OHDA in neuronally differentiated PC12 cells. Among induced pro-apoptotic genes was that encoding the BH3-only protein PUMA.

Bim is a direct target of a neuronal E2F-dependent apoptotic pathway.

The inappropriate expression/activation of cell-cycle-related molecules is associated with neuron death in many experimental paradigms and human neuropathologic conditions. However, the means whereby this links to the core apoptotic machinery in neurons have been unclear. Here, we show that the pro-apoptotic Bcl-2 homology 3 domain-only molecule Bcl-2 interacting mediator of cell death (Bim) is a target of a cell-cycle-related apoptotic pathway in neuronal cells.

B-myb and C-myb play required roles in neuronal apoptosis evoked by nerve growth factor deprivation and DNA damage.

Activation of cell cycle elements plays a required role in neuronal apoptosis associated with both development and neurodegenerative disorders. We demonstrated previously that neuron survival requires gene repression mediated by the cell cycle transcription factor E2F (E2 promoter binding factor) and that apoptotic stimuli lead to de-repression of E2F-regulated genes and consequent death. However, the downstream mediators of such death have been unclear.

Presenilins and gamma-secretase inhibitors affect intracellular trafficking and cell surface localization of the gamma-secretase complex components.

The intramembranous cleavage of Alzheimer beta-amyloid precursor protein and the signaling receptor Notch is mediated by the presenilin (PS, PS1/PS2)-gamma-secretase complex, the components of which also include nicastrin, APH-1, and PEN-2. In addition to its essential role in gamma-secretase activity, we and others have reported that PS1 plays a role in intracellular trafficking of select membrane proteins including nicastrin. Here we examined the fate of PEN-2 in the absence of PS expression or gamma-secretase activity.

Regulation of neuronal survival and death by E2F-dependent gene repression and derepression.

Neuronal death induced by a variety of means requires participation of the E2F family of transcription factors. Here, we show that E2F acts as a gene silencer in neurons and that repression of E2F-responsive genes is required for neuronal survival. Moreover, neuronal death evoked by DNA damaging agents or trophic factor withdrawal is characterized by derepression of E2F-responsive genes.

Cytokines regulate expression of the type 1 interleukin-1 receptor in rat hippocampal neurons and glia.

Interleukin-1 beta is a key mediator of inflammation and stress in the central nervous system (CNS). This cytokine induces CNS glial cells to produce numerous additional cytokines and growth factors under inflammatory conditions. We have investigated regulation of the signal transducing type 1 interleukin-1 receptor (IL-1R1) in the CNS.

Improved NlaIII digestion of PAGE-purified 102 bp ditags by addition of a single purification step in both the SAGE and microSAGE protocols.

Despite the success of microarray technologies, serial analysis of gene expression (SAGE) still remains the only technique that allows an accurate quantitative and qualitative analysis of cell transcription in a variety of physiological and pathological conditions. Nevertheless, the efficiency of SAGE is limited by the numerous gel purification steps required and these increase the possibility of contamination and reduce or inhibit the activity of the enzymes used in the protocol. In order to eliminate this problem, we have modified the original protocol by adding a single purification step before NLA:III digestion of the ditags.

Neurotrophin signaling via Trks and p75.

This review focuses on recent advances in our understanding of receptor-mediated signaling by the neurotrophins NGF, BDNF, NT3, and NT4/5. Two distinct receptor types have been distinguished, Trks and p75. The Trks are receptor tyrosine kinases that utilize a complex set of substrates and adapter proteins to activate defined secondary signaling cascades required for neurotrophin-promoted neuronal differentiation, plasticity, and survival.

Role of cell cycle regulatory proteins in cerebellar granule neuron apoptosis.

Cerebellar granule neurons (CGNs) undergo apoptosis when deprived of depolarizing concentrations of KCl, but the underlying molecular mechanisms are not yet clear. Although caspases have been postulated to be involved in CGN cell death, inhibitors of caspases failed to prevent apoptosis under our culture conditions, suggesting an involvement of other molecules and pathways. We find that inhibitors of cyclin-dependent kinases--flavopiridol, olomoucine, and roscovitine--protect CGNs from KCl withdrawal-induced apoptosis, suggesting that cell cycle components play a significant role in the death of these neurons.

APOE genotype, plasma lipids, lipoproteins, and AD in community elderly.

Background: Genetic variation at the APOE locus has a major influence on both plasma lipid levels and the risk of AD. The relationship between APOE genotype and plasma lipids may influence the risk of AD.

Objective: In a community-based study of white, African American, and Caribbean Hispanic elderly in New York City, we investigated the relationship between plasma lipids and AD as well as the possible influence of APOE genotype on this relationship.

Abnormal microtubule packing in processes of SF9 cells expressing the FTDP-17 V337M tau mutation.

Mutations in the gene for the microtubule associated protein, tau have been identified for fronto-temporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17). In vitro data have shown that FTDP-17 mutant tau proteins have a reduced ability to bind microtubules and to promote microtubule assembly. Using the baculovirus system we have examined the effect of the V337M mutation on the organization of the microtubules at the ultrastructural level.

Caspase-dependent and -independent death of camptothecin-treated embryonic cortical neurons.

This study investigates the mechanisms underlying death of cultured embryonic cortical neurons exposed to the DNA-damaging agent camptothecin and in particular the interdependence of the roles of cyclin-dependent kinases (Cdks), caspases, and mitochondrial function. Camptothecin evokes rapid neuronal death that exhibits nuclear features of apoptosis. This death is accompanied by loss of cytochrome c and mitochondrial transmembrane potential as well as by induction of caspase-3-like activity and caspase-2 processing.

Dibutyryl cyclic AMP-induced process formation in astrocytes is associated with a decrease in tyrosine phosphorylation of focal adhesion kinase and paxillin.

Focal adhesion kinase (FAK or pp125FAK) is a cytosolic protein tyrosine kinase which plays an important role in integrin-mediated signal transduction. Adhesion of cells to the substratum correlates with an increase in tyrosine phosphorylation of FAK as well as an associated protein, paxillin. In this report we show that the tyrosine phosphorylation of FAK and paxillin are decreased during dibutyryl cyclic AMP-induced (dB-cAMP) process formation in astrocytes.

Selective decline in memory function among healthy elderly.

Objective: To use longitudinally acquired data to establish whether aging is associated with memory decline.

Background: Memory loss is one of the most frequent complaints among the elderly. Nevertheless, age-related memory decline remains controversial in large part because it has been established with cross-sectional studies.

Caspase-2 (Nedd-2) processing and death of trophic factor-deprived PC12 cells and sympathetic neurons occur independently of caspase-3 (CPP32)-like activity.

We have previously shown that caspase-2 (Nedd-2) is required for apoptosis induced by withdrawal of trophic support from PC12 cells and sympathetic neurons. Here, we examine the relationship of caspase-2 processing and cell death to induction of caspase-3 (CPP32)-like activity in PC12 cells. Caspase-2 processing, at a site tentatively identified as D333, led to the formation of an N-terminal 37 kDa product.

Process formation in astrocytes: modulation of cytoskeletal proteins.

Studies on primary astrocytes cultured in vitro have shown that process formation involves changes in cytoskeletal proteins and release of tension on the substratum. Actin filament reorganization has previously been found to be the major cytoskeletal change occurring during process formation. These changes are relatively rapid with breakdown of the actin web and release of contacts occur within 15 min.

Multiple pathways of neuronal death induced by DNA-damaging agents, NGF deprivation, and oxidative stress.

Here, we compare the pathways by which DNA-damaging agents, NGF deprivation, and superoxide dismutase 1 (SOD1) depletion evoke apoptosis of sympathetic neurons. Previous work raised the hypothesis that cell cycle signaling plays a required role in neuronal apoptosis elicited by NGF deprivation and the DNA-damaging agent camptothecin. To test this hypothesis, we extended our investigation of DNA-damaging agents to cytosine arabinoside (AraC) and UV irradiation.

Inhibitors of trypsin-like serine proteases inhibit processing of the caspase Nedd-2 and protect PC12 cells and sympathetic neurons from death evoked by withdrawal of trophic support.

Rat pheochromocytoma (PC12) cells and sympathetic neurons undergo apoptotic cell death upon withdrawal of trophic support. We have shown previously that selective cysteine aspartase (caspase) inhibitors protect PC12 cells and sympathetic neurons from such death, and that the caspase Nedd-2 is required for this type of death to occur. We now show that 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride (AEBSF) and N(alpha)-p-tosyl-L-lysine chloromethyl ketone (TLCK), agents that inhibit another class of proteases, the trypsin-like serine proteases, also suppress cell death in this paradigm.

Nedd2 is required for apoptosis after trophic factor withdrawal, but not superoxide dismutase (SOD1) downregulation, in sympathetic neurons and PC12 cells.

Activation of cysteine aspartases (caspases) seems to be a required element of apoptotic death in many paradigms. We have shown previously that general inhibitors of cysteine aspartases block apoptosis of PC12 cells and sympathetic neurons evoked by either trophic factor (nerve growth factor and/or serum) deprivation or superoxide dismutase (SOD1) downregulation. Moreover, activation of a caspase family member similar or equivalent to the interleukin-1beta-converting enzyme (ICE) was implicated for death caused by SOD1 downregulation, but not withdrawal of trophic support.

The course of psychopathologic features in mild to moderate Alzheimer disease.

Background: The onset and course of the psychopathologic features of Alzheimer disease have not been established in prospective, longitudinal studies.

Methods: Two hundred thirty-five patients with early, probable Alzheimer disease were recruited at 3 sites and observed naturalistically for up to 5 years. At 6-month intervals, the Columbia University Scale for Psychopathology in Alzheimer's Disease was administered.