Current Alzheimer Research - Volume 5, Issue 2, 2008

Alois Alzheimer's described his seminal observation more than one hundred years ago. Yet, the main component of one of the principal cerebral lesions, the senile plaque, was only identified in 1984 by Glenner and Wong. This discovery now appears as a temporal frontier between important initial research that was mainly descriptive in nature and a new modern area in which the biology of the disease was investigated and th Read More

Alzheimer's disease is characterized by the presence of two types of lesions in brain: neurofibrillary tangles and senile plaques. Intraneuronal neurofibrillary tangles are made of paired helical filaments containing hyperphosphorylated microtubule associated protein tau. Extracellular senile plaques contain a core of beta-amyloid peptide (Aβ), which is produced by cleavage of the Amyloid Precursor Protein (APP). Among the Read More

Amyloid plaques, hallmark neuropathological lesions in Alzheimer's disease (AD) brain, are composed of the β-amyloid peptide (Aβ). Much evidence suggests that Aβ is central to the pathophysiology of AD and is likely to play an early role in this intractable neurodegenerative disorder. Given the strong correlation between Aβ and AD, therapeutic strategies to lower cerebral Aβ levels should prove beneficial for AD treatment. Aβ is Read More

Memapsin 2 (β-secretase, BACE 1) processing of β-amyloid precursor protein is the first step in the pathway leading to the production of amyloid-β, thus, it is a major target for the development of inhibitor drug for the treatment of Alzheimers's Disease. Although there are distinctive advantages of this protease as a drug target, the development of drug-like memapsin 2 inhibitors has been somewhat slow since the cloning of the Read More

In this review, we discuss the biology of γ-secretase, an enigmatic enzyme complex that is responsible for the generation of the amyloid-β peptide that constitutes the amyloid plaques of Alzheimer's disease. We begin with a brief review on the processing of the amyloid precursor protein and a brief discussion on the family of enzymes involved in regulated intramembrane proteolysis, of which γ-secretase is a member. We then i Read More

Mutations in the presenilin 1 (PS1) gene are the major cause of familial Alzheimer's disease (AD). They effect an increased production of the highly neurotoxic 42 amino acid variant of the amyloid-β peptide (Aβ), which is believed to initiate the disease. Aβ is the product of two consecutive cleavages of the β-amyloid precursor protein (APP) by two proteases, β-secretase and γ-secretase. The latter enzyme has been identifie Read More

γ-Secretase is a multi-protein complex that proteolyzes the transmembrane region of the amyloid β-peptide (Aβ) precursor (APP), producing the Aβ 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 subs Read More

The accumulation and deposition of fibrillar Aβ is thought the primary cause of Alzheimer's disease (AD). Aβ is generated by sequential proteolytic processing involving β- and γ-secretase on Amyloid β protein precursor (APP). Recently, γ-secretase was shown to cleave near the cytoplasmic membrane boundary of APP, called η-site cleavage, as well as in the middle of the membrane domain, called γ-site cleavage. Recent fin Read More

Mutations in two genes, presenilin 1 (PS1) and its homologue presenilin 2 (PS2), account for a majority of early onset familial Alzheimer disease cases which are characterized by intracellular neurofibrillary tangles and extracellular amyloid fibrils composed of the amyloid β protein (Aβ). Aß is derived from sequential cleavages of Amyloid Precursor Protein (APP) by ß-secretase and γ-secretase, the latter is composed of four co Read More

Accumulation of amyloid β-peptides (Aβ) in the brain is believed to contribute to the development of Alzheimer disease (AD). Aβ, a 40-42 amino acid-comprising proteolytical fragment of the amyloid precursor protein (APP), is released from APP by sequential cleavages via β- and γ-secretases. However, the predominant route of APP processing consists of successive cleavages by α- and γ-secretases. Alpha-secretas Read More

Disintegrin metalloproteases of the ADAM family form a large (at present > 40 members in mammals) family of multidomain membrane proteins that in their ectodomain combine a cystein-rich, disintegrin and a zinc metalloprotease domain. Via their metalloprotease domain, ADAMs are often implicated in ectodomain shedding, either to release e.g. growth factors or to initiate further intracellular signalling via regulated intram Read More

Alzheimer's disease (AD) is by far the most common form of dementia in the elderly and concerns one out of three individuals over 85. Like other neurodegenerative disorders such as Parkinson, Hungtington or prion diseases, AD is characterized by the formation of amyloid plaques in the central nervous system. In the brain of AD patients, the main component of these abnormal deposits is an aggregated form of the so-ca Read More

The steady state concentration of the Alzheimer's amyloid-β peptide in the brain represents a balance between its biosynthesis from the transmembrane amyloid precursor protein (APP), its oligomerisation into neurotoxic and stable species and its degradation by a variety of amyloid-degrading enzymes, principally metallopeptidases. These include, among others, neprilysin (NEP) and its homologue endothelin-converti Read More

Neprilysin is a zinc metalloendopeptidase with relatively broad substrate specificity. The enzyme is localized to the plasma membrane of cells where it can function to degrade extracellular peptides. Structural studies show that neprilysin preferentially cleaves peptides on the amino side of hydrophobic amino acids. Neprilysin has been implicated in the catabolism of amyloid β peptides in the brain and as such has received c Read More