Alzheimer Disease: Dingwall C

Dingwall C. · Neurology-CEDD, New Frontiers Science Park, Third Avenue, Harlow CM19 5AW, United · J Clin Invest. · Pubmed #11696563 links to  free full text

This publication has no abstract.

Howlett DR, Simmons DL, Dingwall C, Christie G. · The Dept of Neuroscience Research, SmithKline Beecham Pharmaceuticals, New Frontiers Science Park, Third Avenue, Essex, CM19 5AW, Harlow, UK. · Trends Neurosci. · Pubmed #11074266 No free full text.

Abstract: The deposition of beta-amyloid (Abeta) in the brain is a neuropathological feature of Alzheimer's disease. Abeta is cleaved from its precursor protein (APP) by processing at its N and C termini by enzymes known as beta- and gamma-secretases,respectively. The identity of these enzymes has been elusive but the search for the N-terminal secretase might have ended recently with the almost simultaneous publication by five major laboratories claiming a transmembrane aspartic proteinase to be the long sought after beta-secretase. Even at this early stage of its characterization, this aspartic proteinase fulfils many of the key criteria necessary for beta-secretase.The race is now on to develop inhibitors that could prove effective in halting the progression of Alzheimer's disease.

Beswick P, Charrier N, Clarke B, Demont E, Dingwall C, Dunsdon R, Faller A, Gleave R, Hawkins J, Hussain I, Johnson CN, MacPherson D, Maile G, Matico R, Milner P, Mosley J, Naylor A, O'Brien A, Redshaw S, Riddell D, Rowland P, Skidmore J, Soleil V, Smith KJ, Stanway S, Stemp G, Stuart A, Sweitzer S, Theobald P, Vesey D, Walter DS, Ward J, Wayne G. · Neurology and Gastrointestinal Centre of Excellence for Drug Discovery, GlaxoSmithKline R&D, New Frontiers Science Park, Third Avenue, Harlow, Essex, CM19 5AW, UK. · Bioorg Med Chem Lett. · Pubmed #18171615 No free full text.

Abstract: This article is focusing on further optimization of previously described hydroxy ethylamine (HEA) BACE-1 inhibitors obtained from a focused library with the support of X-ray crystallography. Optimization of the non-prime side of our inhibitors and introduction of a 6-membered sultam substituent binding to Asn-294 as well as a fluorine in the C-2 position led to derivatives with nanomolar potency in cell-based assays.

Clarke B, Demont E, Dingwall C, Dunsdon R, Faller A, Hawkins J, Hussain I, MacPherson D, Maile G, Matico R, Milner P, Mosley J, Naylor A, O'Brien A, Redshaw S, Riddell D, Rowland P, Soleil V, Smith KJ, Stanway S, Stemp G, Sweitzer S, Theobald P, Vesey D, Walter DS, Ward J, Wayne G. · Neurology and Gastrointestinal Centre of Excellence for Drug Discovery, GlaxoSmithKline R&D, New Frontiers Science Park, Third Avenue, Harlow, Essex CM19 5AW, United Kingdom. · Bioorg Med Chem Lett. · Pubmed #18171614 No free full text.

Abstract: Inhibition of the aspartyl protease BACE-1 has the potential to deliver a disease-modifying therapy for Alzheimer's disease. Herein, is described the lead generation effort which resulted, with the support of X-ray crystallography, in the discovery of potent inhibitors based on a hydroxy ethylamine (HEA) transition-state mimetic. These inhibitors were capable of lowering amyloid production in a cell-based assay.

Clarke B, Demont E, Dingwall C, Dunsdon R, Faller A, Hawkins J, Hussain I, MacPherson D, Maile G, Matico R, Milner P, Mosley J, Naylor A, O'Brien A, Redshaw S, Riddell D, Rowland P, Soleil V, Smith KJ, Stanway S, Stemp G, Sweitzer S, Theobald P, Vesey D, Walter DS, Ward J, Wayne G. · Neurology and Gastrointestinal Centre of Excellence for Drug Discovery, GlaxoSmithKline R&D, New Frontiers Science Park, Third Avenue, Harlow, Essex CM19 5AW, United Kingdom. · Bioorg Med Chem Lett. · Pubmed #18166458 No free full text.

Abstract: This paper describes the discovery of non-peptidic, potent, and selective hydroxy ethylamine (HEA) inhibitors of BACE-1 by replacement of the prime side of a lead di-amide 2. Inhibitors with nanosmolar potency and high selectivity were identified. Depending on the nature of the P(1)(') and P(2)(') substituents, two different binding modes were observed in X-ray co-crystal structures.

Dingwall C. · Pharmaceutical Sciences Research Division, King's College London, Franklin-Wilkins Building, Stamford Street, London SE1 9NH, UK. · Biochem Soc Trans. · Pubmed #17511654 No free full text.

Abstract: The amyloidogenic processing pathway of the APP (amyloid precursor protein) generates Abeta (amyloid beta-peptide), the major constituent in Alzheimer's disease senile plaques. This processing is catalysed by two unusual membrane-localized aspartic proteinases, beta-secretase [BACE1 (beta-site APP-cleaving enzyme 1)] and the gamma-secretase complex. There is a clear link between APP processing and copper homoeostasis in the brain. APP binds copper and zinc in the extracellular domain and Abeta also binds copper, zinc and iron. We have found that a 24-residue peptide corresponding to the C-terminal domain of BACE1 binds a single copper(I) atom with high affinity through cysteine residues. We also observed that the cytoplasmic domain of BACE1 interacts with CCS, the dedicated copper chaperone for SOD1 (superoxide dismutase 1). Overproduction of BACE1 reduces SOD1 activity in cells. Consequently, SOD1 activity, cytosolic copper and ectodomain cleavage of APP are linked through BACE1.

Hussain I, Hawkins J, Harrison D, Hille C, Wayne G, Cutler L, Buck T, Walter D, Demont E, Howes C, Naylor A, Jeffrey P, Gonzalez MI, Dingwall C, Michel A, Redshaw S, Davis JB. · Neurology and GastroIntestinal Centre of Excellence for Drug Discovery, GlaxoSmithKline Research & Development Ltd, Harlow, Essex, UK. · J Neurochem. · Pubmed #17156133 No free full text.

Abstract: Generation and deposition of the amyloid beta (Abeta) peptide following proteolytic processing of the amyloid precursor protein (APP) by BACE-1 and gamma-secretase is central to the aetiology of Alzheimer's disease. Consequently, inhibition of BACE-1, a rate-limiting enzyme in the production of Abeta, is an attractive therapeutic approach for the treatment of Alzheimer's disease. We have designed a selective non-peptidic BACE-1 inhibitor, GSK188909, that potently inhibits beta-cleavage of APP and reduces levels of secreted and intracellular Abeta in SHSY5Y cells expressing APP. In addition, we demonstrate that this compound can effectively lower brain Abeta in vivo. In APP transgenic mice, acute oral administration of GSK188909 in the presence of a p-glycoprotein inhibitor to markedly enhance the exposure of GSK188909 in the brain decreases beta-cleavage of APP and results in a significant reduction in the level of Abeta40 and Abeta42 in the brain. Encouragingly, subchronic dosing of GSK188909 in the absence of a p-glycoprotein inhibitor also lowers brain Abeta. This pivotal first report of central Abeta lowering, following oral administration of a BACE-1 inhibitor, supports the development of BACE-1 inhibitors for the treatment of Alzheimer's disease.

Angeletti B, Waldron KJ, Freeman KB, Bawagan H, Hussain I, Miller CC, Lau KF, Tennant ME, Dennison C, Robinson NJ, Dingwall C. · Neurology & Gastrointestinal Centre of Excellence for Drug Discovery, GlaxoSmithKline, New Frontiers Science Park, Harlow, Essex CM19 5AW, United Kingdom. · J Biol Chem. · Pubmed #15722349 links to  free full text

Abstract: The amyloidogenic pathway leading to the production and deposition of Abeta peptides, major constituents of Alzheimer disease senile plaques, is linked to neuronal metal homeostasis. The amyloid precursor protein binds copper and zinc in its extracellular domain, and the Abeta peptides also bind copper, zinc, and iron. The first step in the generation of Abeta is cleavage of amyloid precursor protein by the aspartic protease BACE1. Here we show that BACE1 interacts with CCS (the copper chaperone for superoxide dismutase-1 (SOD1)) through domain I and the proteins co-immunoprecipitate from rat brain extracts. We have also been able to visualize the co-transport of membranous BACE1 and soluble CCS through axons. BACE1 expression reduces the activity of SOD1 in cells consistent with direct competition for available CCS as overexpression of CCS restores SOD1 activity. Finally, we demonstrate that the twenty-four residue C-terminal domain of BACE1 binds a single Cu(I) atom with high affinity through cysteine residues.

Abad-Rodriguez J, Ledesma MD, Craessaerts K, Perga S, Medina M, Delacourte A, Dingwall C, De Strooper B, Dotti CG. · Cavalieri Ottolenghi Scientific Institute, Universita degli Studi di Torino, Orbassano, Italy. · J Cell Biol. · Pubmed #15583033 links to  free full text

Abstract: Recent experimental and clinical retrospective studies support the view that reduction of brain cholesterol protects against Alzheimer's disease (AD). However, genetic and pharmacological evidence indicates that low brain cholesterol leads to neurodegeneration. This apparent contradiction prompted us to analyze the role of neuronal cholesterol in amyloid peptide generation in experimental systems that closely resemble physiological and pathological situations. We show that, in the hippocampus of control human and transgenic mice, only a small pool of endogenous APP and its beta-secretase, BACE 1, are found in the same membrane environment. Much higher levels of BACE 1-APP colocalization is found in hippocampal membranes from AD patients or in rodent hippocampal neurons with a moderate reduction of membrane cholesterol. Their increased colocalization is associated with elevated production of amyloid peptide. These results suggest that loss of neuronal membrane cholesterol contributes to excessive amyloidogenesis in AD and pave the way for the identification of the cause of cholesterol loss and for the development of specific therapeutic strategies.

Harrison SM, Harper AJ, Hawkins J, Duddy G, Grau E, Pugh PL, Winter PH, Shilliam CS, Hughes ZA, Dawson LA, Gonzalez MI, Upton N, Pangalos MN, Dingwall C. · Department of Comparative Genomics, GlaxoSmithKline, New Frontiers Science Park (North), Third Avenue, Harlow, Essex CM19 5AW, UK. · Mol Cell Neurosci. · Pubmed #14664815 No free full text.

Abstract: BACE1 is a key enzyme in the generation of Abeta, the major component of senile plaques in the brains of Alzheimer's disease patients. We have generated transgenic mice expressing human BACE1 with the Cam Kinase II promoter driving neuronal-specific expression. The transgene contains the full-length coding sequence of human BACE1 preceding an internal ribosome entry site element followed by a LacZ reporter gene. These animals exhibit a bold, exploratory behavior and show elevated 5-hydroxytryptamine turnover. We have also generated a knockout mouse in which LacZ replaces the first exon of murine BACE1. Interestingly these animals show a contrasting behavior, being timid and less exploratory. Despite these clear differences both mouse lines are viable and fertile with no changes in morbidity. These results suggest an unexpected role for BACE1 in neurotransmission, perhaps through changes in amyloid precursor protein processing and Abeta levels.

Ledesma MD, Abad-Rodriguez J, Galvan C, Biondi E, Navarro P, Delacourte A, Dingwall C, Dotti CG. · Cavalieri Ottolenghi Scientific Institute, Universita degli Studi di Torino, A.O. San Luigi Gonzaga, Regione Gonzole 10, 10043 Orbassano (TO), Italy. · EMBO Rep. · Pubmed #14618158 links to  free full text

Abstract: The serine protease plasmin can efficiently degrade amyloid peptide in vitro, and is found at low levels in the hippocampus of patients with Alzheimer's disease (AD). The cause of such paucity remains unknown. We show here that the levels of total brain plasminogen and plasminogen-binding molecules are normal in these brain samples, yet plasminogen membrane binding is greatly reduced. Biochemical analysis reveals that the membranes of these brains have a mild, still significant, cholesterol reduction compared to age-matched controls, and anomalous raft microdomains. This was reflected by the loss of raft-enriched proteins, including plasminogen-binding and -activating molecules. Using hippocampal neurons in culture, we demonstrate that removal of a similar amount of membrane cholesterol is sufficient to induce raft disorganization, leading to reduced plasminogen membrane binding and low plasmin activity. These results suggest that brain raft alterations may contribute to AD by rendering the plasminogen system inefficient.

Lau KF, Howlett DR, Kesavapany S, Standen CL, Dingwall C, McLoughlin DM, Miller CC. · Department of Neuroscience, The Institute of Psychiatry, King's College London, De Crespigny Park, Denmark Hill, United Kingdom. · Mol Cell Neurosci. · Pubmed #12056836 No free full text.

Abstract: Mutations in the Presenilin 1 gene are the cause of the majority of autosomal dominant familial forms of Alzheimer's disease. Presenilin 1 (PS1) is produced as a holoprotein but is then rapidly processed to amino- (N-PS1) and carboxy-terminal (C-PS1) fragments that are incorporated into stable high molecular mass complexes. The mechanisms that control PS1 cleavage and stability are not properly understood but sequences within C-PS1 have been shown to regulate both of these properties. Here we demonstrate that cyclin dependent kinase-5/p35 (cdk5/p35) phosphorylates PS1 on threonine(354) within C-PS1 both in vitro and in vivo. Threonine(354) phosphorylation functions to selectively stabilize C-PS1. Our results demonstrate that cdk5/p35 is a regulator of PS1 metabolism.

Riddell DR, Christie G, Hussain I, Dingwall C. · Neurology Centre of Excellence for Drug Discovery, GlaxoSmithKline, New Frontiers Science Park, Third Avenue, Harlow CM19 5AW, United Kingdom. · Curr Biol. · Pubmed #11525745 No free full text.

Abstract: Recent epidemiological studies show a reduced prevalence of Alzheimer's disease (AD) in patients treated with inhibitors of cholesterol biosynthesis. Moreover, the cholesterol-transport protein, apolipoprotein E4, and elevated cholesterol are important risk factors for AD. Additionally, in vitro and in vivo studies show that intracellular cholesterol levels can modulate the processing of amyloid precursor protein (APP) to beta-amyloid, the major constituent of senile plaques. Cholesterol plays a crucial role in maintaining lipid rafts in a functional state. Lipid rafts are cholesterol-enriched membrane microdomains implicated in signal transduction, protein trafficking, and proteolytic processing. Since APP, beta-amyloid, and the putative gamma-secretase, presenilin-1 (PS-1), have all been found in lipid rafts, we hypothesized that the recently identified beta-secretase, Asp2 (BACE1), might also be present in rafts. Here, we report that recombinant Asp2 expressed in three distinct cell lines is raft associated. Using both detergent and nondetergent methods, Asp2 protein and activity were found in a light membrane raft fraction that also contained other components of the amyloidogenic pathway. Immunoisolation of caveolin-containing vesicles indicated that Asp2 was present in a unique raft population distinct from caveolae. Finally, depletion of raft cholesterol abrogated association of Asp2 with the light membrane fraction. These observations are consistent with the raft localization of APP processing and suggest that the partitioning of Asp2 into lipid rafts may underlie the cholesterol sensitivity of beta-amyloid production.

Charlwood J, Dingwall C, Matico R, Hussain I, Johanson K, Moore S, Powell DJ, Skehel JM, Ratcliffe S, Clarke B, Trill J, Sweitzer S, Camilleri P. · Department of Analytical Sciences, SmithKline Beecham Pharmaceuticals, Harlow, Essex CM19 5AW, United Kingdom. · J Biol Chem. · Pubmed #11278492 links to  free full text

Abstract: Amyloid 39-42 beta -peptides are the main components of amyloid plaques found in the brain of Alzheimer's disease patients. Amyloid 39-42 beta-peptide is formed from amyloid precursor protein by the sequential action of beta- and gamma-secretases. Asp-2 is a transmembrane aspartic protease expressed in the brain, shown to have beta-secretase activity. Mature Asp-2 has four N-glycosylation sites. In this report we have characterized the carbohydrate structures in this glycoprotein expressed in three different cell lines, namely Chinese hamster ovary, CV-1 origin of SV40, and baculovirus-infected SF9 cells. Biantennary and triantennary oligosaccharides of the "complex" type were released from glycoprotein expressed in the mammalian cells, whereas mannose-rich glycans were identified from glycoprotein synthesized in the baculovirus-infected cells. Site-directed mutagenesis of the asparagine residues at amino acid positions 153, 172, 223, and 354 demonstrate that the protease activity of Asp-2 is dependent on its glycosylation.

Hussain I, Powell D, Howlett DR, Tew DG, Meek TD, Chapman C, Gloger IS, Murphy KE, Southan CD, Ryan DM, Smith TS, Simmons DL, Walsh FS, Dingwall C, Christie G. · Department of Neurosciences, SmithKline Beecham Pharmaceuticals, Harlow, Essex, United Kingdom. · Mol Cell Neurosci. · Pubmed #10656250 No free full text.

Abstract: The Alzheimer's disease beta-amyloid peptide (Abeta) is produced by excision from the type 1 integral membrane glycoprotein amyloid precursor protein (APP) by the sequential actions of beta- and then gamma-secretases. Here we report that Asp 2, a novel transmembrane aspartic protease, has the key activities expected of beta-secretase. Transient expression of Asp 2 in cells expressing APP causes an increase in the secretion of the N-terminal fragment of APP and an increase in the cell-associated C-terminal beta-secretase APP fragment. Mutation of either of the putative catalytic aspartyl residues in Asp 2 abrogates the production of the fragments characteristic of cleavage at the beta-secretase site. The enzyme is present in normal and Alzheimer's disease (AD) brain and is also found in cell lines known to produce Abeta. Asp 2 localizes to the Golgi/endoplasmic reticulum in transfected cells and shows clear colocalization with APP in cells stably expressing the 751-amino-acid isoform of APP.

Doglio LE, Kanwar R, Jackson GR, Perez M, Avila J, Dingwall C, Dotti CG, Fortini ME, Feiguin F. · Cavalieri Ottolenghi Scientific Institute, Universita degli Studi di Torino, 10043, Orbassano, Torino, Italy. · Neuron. · Pubmed #16675392 No free full text.

Abstract: Genetic analysis of familial Alzheimer's disease has revealed that mutations in the gamma-secretase enzyme presenilin promote toxic Abeta secretion; however, presenilin mutations might also influence tau hyperphosphorylation and neurodegeneration through gamma-secretase-independent mechanisms. To address this possibility and determine whether other components of the gamma-secretase complex possess similar regulatory functions, we analyzed the roles of presenilin, nicastrin, and aph-1 in a Drosophila model for tau-induced neurodegeneration. Here, we show that presenilin and nicastrin prevent tau toxicity by modulating the PI3K/Akt/GSK3beta phosphorylation pathway, whereas aph-1 regulates aPKC/PAR-1 activities. Moreover, we found that these transmembrane proteins differentially regulate the intracellular localization of GSK3beta and aPKC at cell junctions. Inhibition of gamma-secretase activity neither interfered with these kinase pathways nor induced aberrant tau phosphorylation. These results establish new in vivo molecular functions for the three components of the gamma-secretase complex and reveal a different mechanism that might contribute to neuronal degeneration in Alzheimer's disease.