ABSTRACT
Overwhelming evidence indicates that the Abeta (amyloid beta-peptide) plays a critical role in the pathogenesis of Alzheimer's disease. Abeta is derived from the APP (amyloid precursor protein) by the action of two aspartyl proteases (beta- and gamma-secretases) that are leading candidates for therapeutic intervention. APP is a member of a multigene family that includes APLP1 (amyloid precursor-like protein 1) and APLP2. Both APLPs are processed in a manner analogous to APP, with all three proteins subject to ectodomain shedding and subsequent cleavage by gamma-secretase. Careful study of the APP family of proteins has already revealed important insights about APP. Here, we will review how knowledge of the similarities and differences between APP and the APLPs may prove useful for the development of novel disease-modifying therapeutics.
Subject(s)
Alzheimer Disease/physiopathology , Amyloid beta-Peptides/physiology , Amyloid beta-Protein Precursor/physiology , Brain/physiology , Receptors, Cell Surface/physiology , Animals , Brain/physiopathology , Humans , Protease Nexins , Reference ValuesABSTRACT
Genetic evidence indicates a central role of cerebral accumulation of beta-amyloid (Abeta) in the pathogenesis of Alzheimer's disease (AD). Beside presenilin 1 and 2, three other recently discovered proteins (Aph 1, PEN 2 and nicastrin) are associated with gamma-secretase activity, the enzymatic complex generating Abeta. Alterations in genes encoding these proteins were candidates for a role in AD. The PEN 2 gene was examined for unknown mutations and polymorphisms in sporadic and familial Alzheimer patients. Samples from age-matched controls (n=253), sporadic AD (SAD, n=256) and familial AD (FAD, n=140) were screened with DHPLC methodology followed by sequencing. Scanning the gene identified for the first time a missense mutation (D90N) in a patient with FAD. Three intronic polymorphisms were also identified, one of which had a higher presence of the mutated allele in AD subjects carrying the allele epsilon4 of apolipoprotein E than controls. The pathogenic role of the PEN-2 D90N mutation in AD is not clear, but the findings might lead to new studies on its functional and genetic role.
