Alzheimer Disease: Wolfe MS

Li H, Wolfe MS, Selkoe DJ. · Biology Department, Brookhaven National Laboratory, Upton, NY 11973-5000, USA. · Structure. · Pubmed #19278647 No free full text.

Abstract: Gamma-Secretase is an intramembrane protease complex that mediates the Notch signaling pathway and the production of amyloid beta-proteins. As such, this enzyme has emerged as an important target for development of novel therapeutics for Alzheimer disease and cancer. Great progress has been made in the identification and characterization of the membrane complex and its biological functions. One major challenge now is to illuminate the structure of this fascinating and important protease at atomic resolution. Here, we review recent progress on biochemical and biophysical probing of the structure of the four-component complex and discuss obstacles and potential pathways toward elucidating its detailed structure.

Wolfe MS. · Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, 77 Avenue Louis Pasteur, Boston, MA 02115 USA. · Semin Cell Dev Biol. · Pubmed #19162210 No free full text.

Abstract: gamma-Secretase is a membrane-embedded proteolytic complex composed of presenilin and three other subunits. The gamma-secretase complex generates the amyloid beta-peptide of Alzheimer's disease but also plays important roles in normal physiology, especially in signaling from the Notch receptor. How this hydrolytic enzyme works in a hydrophobic environment is largely unanswered, but mutagenesis and chemical probes have offered insight. gamma-Secretase is an important therapeutic target, although mechanism-based toxicity presents a serious obstacle. Agents that lower amyloid beta-peptide production while leaving important normal functions of gamma-secretase intact are promising therapeutic leads. Inhibition of Notch signaling by gamma-secretase inhibitors, which is undesirable for the prevention or treatment of Alzheimer's disease, may be beneficial for the treatment of a variety of cancers.

Wolfe MS. · Center for Neurologic Diseases, Brigham & Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. · BMC Neurosci. · Pubmed #19090992 links to  free full text

Abstract: The amyloid-beta peptide (Abeta), implicated in the pathogenesis of Alzheimer's disease (AD), is produced through sequential proteolysis of the Abeta precursor protein (APP) by beta- and gamma-secretases. Thus, blocking either of these two proteases, directly or indirectly, is potentially worthwhile toward developing AD therapeutics. beta-Secretase is a membrane-tethered pepsin-like aspartyl protease suitable for structure-based design, whereas gamma-secretase is an unusual, heterotetrameric membrane-embedded aspartyl protease. While gamma-secretase inhibitors entered clinical trials first due to their superior pharmacological properties (for example, brain penetration) over beta-secretase inhibitors, it has since become clear that gamma-secretase inhibitors can cause mechanism-based toxicities owing to interference with the proteolysis of another gamma-secretase substrate, the Notch receptor. Strategies for targeting Abeta production at the gamma-secretase level without blocking Notch signalling will be discussed. Other strategies utilizing cell-based screening have led to the identification of novel Abeta lowering agents that likewise leave Notch proteolysis intact. The mechanism by which these agents lower Abeta is unknown, but these compounds may ultimately reveal new targets for AD therapeutics.

Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. · J Biol Chem. · Pubmed #18948254 No free full text.

Abstract: Tau deposition is found in a variety of neurodegenerative brain diseases. The identification of tau mutations that cause familial dementia demonstrated that aberrant Tau alone could cause neurodegenerative disease and suggested that Tau likely plays a role in other cases in which Tau deposits are found, most notably Alzheimer disease. The mechanisms by which tau mutations cause neurodegeneration vary and are unclear to some degree, but evidence supports changes in alternative splicing, phosphorylation state, interaction with tubulin, and self-association into filaments as important contributing factors.

Wolfe MS. · Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts 02115, USA. · Neurotherapeutics. · Pubmed #18625450 links to  free full text

Abstract: The 4-kDa amyloid beta-peptide (Abeta) is strongly implicated the pathogenesis of Alzheimer's disease (AD), and this peptide is cut out of the amyloid beta-protein precursor (APP) by the sequential action of beta- and gamma-secretases. gamma-Secretase is a membrane-embedded protease complex that cleaves the transmembrane region of APP to produce Abeta, and this protease is a top target for developing AD therapeutics. A number of inhibitors of the gamma-secretase complex have been identified, including peptidomimetics that block the active site, helical peptides that interact with the initial substrate docking site, and other less peptide-like, more drug-like compounds. To date, one gamma-secretase inhibitor has advanced into late-phase clinical trials for the treatment of AD, but serious concerns remain. The gamma-secretase complex cleaves a number of other substrates, and gamma-secretase inhibitors cause in vivo toxicities by blocking proteolysis of one essential substrate, the Notch receptor. Thus, compounds that modulate gamma-secretase, rather than inhibit it, to selectively alter Abeta production without hindering signal transduction from the Notch receptor would be more ideal. Such modulators have been discovered and advanced, with one compound in late-phase clinical trials, renewing interest in gamma-secretase as a therapeutic target.

Wolfe MS. · Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115, USA. · Curr Alzheimer Res. · Pubmed #18393800 links to  free full text

Abstract: Gamma-secretase is a multi-protein complex that proteolyzes the transmembrane region of the amyloid beta-peptide (Abeta) precursor (APP), producing the Abeta peptide implicated in the pathogenesis of Alzheimer's disease (AD). This protease has been a top target for AD, and various inhibitors have been identified, including transition-state analogue inhibitors that interact with the active site, helical peptides that interact with the initial substrate docking site, and other less peptide-like, more drug-like compounds. Although one gamma-secretase inhibitor has advanced into late-phase clinical trials, concerns about inhibiting this protease remain. The protease complex cleaves a number of other substrates, and in vivo toxicities observed with gamma-secretase inhibitors are apparently due to blocking one particularly important substrate, the Notch receptor. Thus, the potential of gamma-secretase as therapeutic target likely depends on the ability to selectively inhibit Abeta production without hindering Notch proteolysis (i.e., modulation rather than inhibition). The discovery of gamma-secretase modulators has revived gamma-secretase as an attractive target and has so far resulted in one compound in late-phase clinical trials. The identification of other modulators in a variety of structural classes raise the hope that more promising agents will soon be in the pipeline.

Wolfe MS. · Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115, USA. · Curr Top Med Chem. · Pubmed #18220927 No free full text.

Abstract: Gamma-secretase proteolyzes a variety of membrane-associated fragments derived from type I integral membrane proteins, including the amyloid beta-protein precursor, involved in Alzheimer's disease, and the Notch receptor, critical for cellular differentiation. This protease is composed of four integral membrane proteins: presenilin, nicastrin, Aph-1 and Pen-2. Assembly of these four components leads to presenilin autoproteolysis into two subunits, each of which contributes one aspartate to the active site of an aspartyl protease. The protease contains an initial docking site for substrate, where it binds prior to passing between the two presenilin subunits to the internal water-containing active site. The extracellular region of nicastrin also interacts with the N-terminus of the substrate as an essential step in substrate recognition and processing. Modulation of APP processing without interfering with Notch signaling is an important therapeutic goal, and allosteric sites on the protease allow such selective modulation. A better structural and mechanistic understanding of gamma-secretase should ultimately allow structure-based design of more potent and selective modulators.

Selkoe DJ, Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA. · Cell. · Pubmed #17956719 No free full text.

Abstract: The presenilin-containing gamma-secretase complex is an unusual membrane-embedded protease that processes a wide variety of integral membrane proteins, clearing protein stubs from the lipid bilayer and participating in critical signaling pathways. The protease is also central to Alzheimer's disease and certain cancers and is therefore an important therapeutic target. Here we highlight recent progress in deciphering the role of presenilin/gamma-secretase in biology and medicine and pose key questions for future study.

Wolfe MS, Guénette SY. · Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA. · J Cell Sci. · Pubmed #17878232 links to  free full text

This publication has no abstract.

Wolfe MS. · Center for Neurologic Diseases, Harvard Medical School, Brigham and Women's Hospital, 77 Avenue Louis Pasteur, Harvard Institute of Medicine 754, Boston, Massachusetts 02115, USA. · EMBO Rep. · Pubmed #17268504 links to  free full text

Abstract: More than 100 missense mutations in presenilin 1 and 2 are associated with early-onset dominant Alzheimer disease. These proteins span the membrane several times and are ostensibly the catalytic component of the gamma-secretase complex, which is responsible for producing the amyloid beta-peptide (Abeta) that deposits in the Alzheimer brain. A common outcome of Alzheimer-associated presenilin mutations is an increase in the ratio of the more aggregation-prone 42-residue form of Abeta to the 40-residue variant, which is often referred to as a presenilin 'gain of function'. An apparent paradox is that most of these mutant presenilins have reduced proteolytic efficiency, which forms part of the counter argument that presenilin 'loss of function' can cause the neuronal dysfunction and death that lead to the disease. In this review, a unifying hypothesis is presented that puts forward a biochemical mechanism by which slower less-efficient forms of the protease can result in a greater proportion of 42-residue Abeta.

Kimberly WT, Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. · J Neurosci Res. · Pubmed #14598311 No free full text.

Abstract: gamma-Secretase catalyzes intramembrane proteolysis of various type I membrane proteins, including the amyloid-beta precursor protein and the Notch receptor. Despite its importance in the pathogenesis of Alzheimer's disease and to normal development, this protease has eluded identification until only very recently. Four membrane proteins are now known to be members of the protease complex: presenilin, nicastrin, aph-1, and pen-2. Recent findings suggest that these four proteins are sufficient to reconstitute the active gamma-secretase complex and that together they mediate the cell surface signaling of a variety of receptors via intramembrane proteolysis.

Xia W, Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA. · J Cell Sci. · Pubmed #12808018 links to  free full text

Abstract: Regulated intramembrane proteolysis is a novel mechanism involving proteases that hydrolyze their substrates in a hydrophobic environment. Presenilin (PS) 1 and PS 2 are required for intramembrane cleavage of an increasing number of type I membrane proteins, including the amyloid precursor protein of Alzheimer's disease and the Notch receptor, which signals during differentiation and development. Mutagenesis, affinity labeling, biochemical isolation, and reconstitution in cells reveal that PS, in complex with co-factors nicastrin, APH-1 and PEN-2, apparently contains the active site of gamma-secretase, a novel membrane aspartyl protease. In addition, other related aspartyl proteases have been identified. These include members of the type-4 prepilin peptidase family in bacteria, which are known proteases and carry a GD motif conserved in PS. A group of multi-pass membrane proteins found in eukaryotes also contain YD and LGXGD motifs in two transmembrane domains that are conserved in PS and postulated to constitute an aspartyl protease active site. Among these is signal peptide peptidase (SPP), which cleaves remnant signal peptides derived from signal-peptidase-mediated ectodomain shedding. SPP cuts type II membrane proteins, illustrating that PS-like proteases play a key role in intramembrane proteolysis of single-pass membrane proteins oriented in either direction.

Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. · Curr Top Dev Biol. · Pubmed #12696752 No free full text.

This publication has no abstract.

Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, 77 Avenue Louis Pasteur, H.I.M. 626, Boston, MA 02115, USA. · Int Immunopharmacol. · Pubmed #12489805 No free full text.

Abstract: Deposition of the amyloid-beta protein (Abeta) in the form of cerebral plaques is a defining pathological feature of Alzheimer's disease (AD), and all AD-causing genes identified to date affect Abeta production or deposition. For these reasons, the two proteases, beta- and gamma-secretases, that cut out Abeta from the amyloid-beta precursor protein (APP) are considered important targets for the development of therapeutics for AD. AD-causing mutations in the presenilin genes alter y-secretase activity, increasing production of the more deleterious 42-residue form of Abeta. Pharmacological profiling, site-directed mutagenesis, knockout studies, affinity labeling, and activity-dependent chromatography all strongly support the hypothesis that presenilin is an integral component of gamma-secretase, a founding member of an emerging class of polytopic membrane proteases. Gamma-Secretase/ presenilin also cleaves other proteins that are important for critical signaling events (the Notch family of receptors), raising concerns about mechanism-based toxicities that might arise as a consequence of inhibiting this protease. In light of these findings, the potential of gamma-secretase vis-à-vis beta-secretase as therapeutic targets for the prevention or treatment of AD will be discussed.

Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital, 77 Avenue Louis Pasteur, HIM 754, Boston, Massachusetts 02115, USA. · Nat Rev Drug Discov. · Pubmed #12415246 No free full text.

Abstract: Alzheimer's disease is a progressive and ultimately fatal neurological disorder for which there is no effective treatment at present. The disease is characterized pathologically by cerebral plaques that contain the amyloid-beta peptide and thread-like neuronal structures composed of the microtubule-associated protein TAU. Both amyloid-beta and TAU are thought to be crucial to pathogenesis, but compelling evidence supports amyloid-beta as the 'prime mover'. The main efforts for developing therapeutics are therefore focused on preventing amyloid-beta production, aggregation or downstream neurotoxic events. The progress of these and other approaches raises the hope that effective agents for the prevention and treatment of Alzheimer's disease will be available in the near future.

Tsai JY, Wolfe MS, Xia W. · PPG Industrial, 440 College Park Drive, Monroeville, PA 15146, USA. · Curr Med Chem. · Pubmed #12052174 No free full text.

Abstract: A considerable body of evidence has accumulated in recent years implicating the beta-amyloid protein (Abeta) in the etiology of Alzheimer s disease (AD). The highly hydrophobic Abeta can nucleate and form neurotoxic fibrils that are the principal components of the cerebral plaques characteristic of AD. Abeta is formed from the amyloid-beta precursor protein (APP) through two protease activities. First, beta-secretase cleaves APP at the Abeta N-terminus, resulting in a soluble, secreted APP derivative (beta-APPs) and a 12 kDa membrane-retained C-terminal fragment. The latter is further processed to Abeta by gamma secretases, which cleave within the single transmembrane region. Other APP molecules can be cleaved by alpha-secretase within the Abeta region, thus precluding Abeta formation. Both beta- and gamma- secretase have become prime targets for the development of therapeutic agent that reduce Abeta production. Beta-secretase has recently been identified as a new membrane-anchored aspartyl protease in the cathepsin D family. Inhibitor profiling, site-directed mutagenesis, and affinity labeling together have suggested that the multi-pass presenilins are gamma-secretases, novel intramembrane-cleaving aspartyl proteases activated through autoproteolysis. In this article, we review the current knowledge of gamma-secretase biochemistry and cell biology and the development of inhibitors of this important therapeutic target.

Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital, 77 Avenue Louis Pasteur, H.I.M. 626, Boston, MA 02115, USA. · Curr Top Med Chem. · Pubmed #11966461 No free full text.

Abstract: The amyloid-beta peptide (Abeta) is the major protein component of the characteristic cerebral plaques of Alzheimer s disease (AD), and a large body of evidence supports a pathogenic role for this peptide. Thus, the proteases beta- and gamma-secretase that are responsible for carving Abeta out of its precursor protein are considered prime targets for therapeutic design. beta-Secretase is a membrane-anchored aspartyl protease of the pepsin family, while gamma-secretase is much more complex. gamma-Secretase requires presenilin, a multipass membrane protein that is the site of dozens of missense mutations that alter Abeta formation and cause hereditary AD. Two conserved aspartates in presenilin are required for gamma-secretase activity, and aspartyl protease transition-state analogue inhibitors of gamma-secretase bind directly to presenilins, strong evidence that presenilin is the catalytic component of a novel membrane aspartyl protease. gamma-Secretase appears to be a multi-component complex of integral membrane proteins, and so far presenilin and a single-pass membrane protein called nicastrin have been identified as members of this complex. A closely similar or identical protease activity is essential for a signaling pathway critical for embryogenesis and hematopoiesis, raising concerns about gamma-secretase as a target. The development of potent and selective inhibitors with good pharmacokinetic properties may soon address these concerns.

Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. · J Mol Neurosci. · Pubmed #11816793 No free full text.

Abstract: Mutations in the presenilins cause Alzheimer's disease (AD) and alter gamma-secretase activity to increase the production of the 42-residue amyloid-beta peptide (Abeta) found disproportionally in the cerebral plaques that characterize the disease. The serpentine presenilins are required for transmembrane cleavage of both the amyloid-beta precursor protein (APP) and the Notch receptor by y-secretase, and presenilins are biochemically associated with the protease. Inhibitors of gamma-secretase have provided critical clues to the function of presenilins. Pharmacological profiling suggested that gamma-secretase is an aspartyl protease, leading to the identification of two conserved aspartates important to presenilin's role in proteolysis. Conversion of transition-state analogue inhibitors of gamma-secretase to affinity reagents resulted in specific tagging of the heterodimeric form of presenilins, strongly suggesting that the active site of gamma-secretase lies at the interface of the presenilin heterodimer. Heterodimeric presenilin appears to be the catalytic portion of a multi-protein gamma-secretase complex.

Esler WP, Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. · Science. · Pubmed #11520976 No free full text.

Abstract: The amyloid beta-peptide (Abeta) is a principal component of the cerebral plaques found in the brains of patients with Alzeheimer's disease (AD). This insoluble 40- to 42-amino acid peptide is formed by the cleavage of the Abeta precursor protein (APP). The three proteases that cleave APP, alpha-, beta-, and gamma-secretases, have been implicated in the etiology of AD. beta-Secretase is a membrane-anchored protein with clear homology to soluble aspartyl proteases, and alpha-secretase displays characteristics of certain membrane-tethered metalloproteases. gamma-Secretase is apparently an oligomeric complex that includes the presenilins, which may be the catalytic component of this protease. Identification of the alpha-, beta-, and gamma-secretases provides potential targets for designing new drugs to treat AD.

Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA. · J Med Chem. · Pubmed #11405641 No free full text.

This publication has no abstract.

Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA. · J Neurochem. · Pubmed #11259478 No free full text.

This publication has no abstract.

Wolfe MS, Haass C. · Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts 02115, USA. · J Biol Chem. · Pubmed #11134059 links to  free full text

This publication has no abstract.

Wolfe MS, De Los Angeles J, Miller DD, Xia W, Selkoe DJ. · Department of Pharmaceutical Sciences, University of Tennessee, Memphis 38163, USA. · Biochemistry. · Pubmed #10471271 No free full text.

Abstract: The amyloid-beta protein (Abeta) is strongly implicated in the pathogenesis of Alzheimer's disease. The final step in the production of Abeta from the amyloid precursor protein (APP) is proteolysis by the unidentified gamma-secretases. This cleavage event is unusual in that it apparently occurs within the transmembrane region of the substrate. Studies with substrate-based inhibitors together with molecular modeling and mutagenesis of the gamma-secretase cleavage site of APP suggest that gamma-secretases are aspartyl proteases that catalyze a novel intramembranous proteolysis. This proteolysis requires the presenilins, proteins with eight transmembrane domains that are mutated in most cases of autosomal dominant familial Alzheimer's disease. Two conserved transmembrane aspartates in presenilins are essential for gamma-secretase activity, suggesting that presenilins themselves are gamma-secretases. Moreover, presenilins also mediate the apparently intramembranous cleavage of the Notch receptor, an event critical for Notch signaling and embryonic development. Thus, if presenilins are gamma-secretases, then they are also likely the proteases that cleave Notch within its transmembrane domain. Another protease, S2P, involved in the processing of the sterol regulatory element binding protein, is also a multipass integral membrane protein which cleaves within or very close to the transmembrane region of its substrate. Thus, presenilins and S2P appear to be members of a new type of polytopic protease with an intramembranous active site.

Mowrer KR, Wolfe MS. · Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA. · J Neurochem. · Pubmed #19302194 No free full text.

Abstract: beta-site APP cleaving enzyme 1 (BACE1) is the transmembrane aspartyl protease that catalyzes the first cleavage step during proteolysis of the beta-amyloid precursor protein, a process involved in the pathogenesis of Alzheimer disease. BACE1 pre-mRNA undergoes complex alternative splicing, and cis-acting elements important for its regulation have not been identified. We constructed and compared several BACE1 minigenes and found that BACE1 sequence from exon 3 through exon 5 was required for minigenes to undergo correct splicing. Minigene splicing was validated by showing specific splicing inhibition upon splice site mutation. Furthermore, we showed that mutation of the minigene at a predicted exonic splicing enhancer in exon 4 of BACE1 increased exon 4 skipping. Therefore, we have for the first time found evidence of a regulatory site involved in BACE1 alternative splicing, and these data indicate that minor sequence changes can dramatically alter BACE1 alternative splicing.

Kukar TL, Ladd TB, Bann MA, Fraering PC, Narlawar R, Maharvi GM, Healy B, Chapman R, Welzel AT, Price RW, Moore B, Rangachari V, Cusack B, Eriksen J, Jansen-West K, Verbeeck C, Yager D, Eckman C, Ye W, Sagi S, Cottrell BA, Torpey J, Rosenberry TL, Fauq A, Wolfe MS, Schmidt B, Walsh DM, Koo EH, Golde TE. · Department of Neuroscience, Mayo Clinic, Mayo Clinic College of Medicine, 4500 San Pablo Road, Jacksonville, Florida 32224, USA. · Nature. · Pubmed #18548070 links to  free full text

Abstract: Selective lowering of Abeta42 levels (the 42-residue isoform of the amyloid-beta peptide) with small-molecule gamma-secretase modulators (GSMs), such as some non-steroidal anti-inflammatory drugs, is a promising therapeutic approach for Alzheimer's disease. To identify the target of these agents we developed biotinylated photoactivatable GSMs. GSM photoprobes did not label the core proteins of the gamma-secretase complex, but instead labelled the beta-amyloid precursor protein (APP), APP carboxy-terminal fragments and amyloid-beta peptide in human neuroglioma H4 cells. Substrate labelling was competed by other GSMs, and labelling of an APP gamma-secretase substrate was more efficient than a Notch substrate. GSM interaction was localized to residues 28-36 of amyloid-beta, a region critical for aggregation. We also demonstrate that compounds known to interact with this region of amyloid-beta act as GSMs, and some GSMs alter the production of cell-derived amyloid-beta oligomers. Furthermore, mutation of the GSM binding site in the APP alters the sensitivity of the substrate to GSMs. These findings indicate that substrate targeting by GSMs mechanistically links two therapeutic actions: alteration in Abeta42 production and inhibition of amyloid-beta aggregation, which may synergistically reduce amyloid-beta deposition in Alzheimer's disease. These data also demonstrate the existence and feasibility of 'substrate targeting' by small-molecule effectors of proteolytic enzymes, which if generally applicable may significantly broaden the current notion of 'druggable' targets.