APP 228

Alzheimer's disease, the most common cause of dementia in the elderly, exists in both familial and sporadic forms. Genetic studies have identified three genes; beta-amyloid precursor protein (APP), Presenilin 1 and Presenilin 2 which, when mutated, can cause familial forms of Alzheimer's disease. APP and APP-like proteins are transmembrane glycoproteins with a similar modular domain structure.

APP-228 has been raised to the extracellular portion of APP between the Kunitz protease inhibitor domain and the beta amyloid region. This region shows the least homology with the APP-like proteins. APP-228 and does not cross-react with APP-like proteins. APP reacts with large pyramidal cells as well as smaller neurons, astrocytes and microglia. APP 228 reacts with late-stage neurofibrillary tangle-bearing neurons, neuritic processes surrounding senile plaques and neuropil threads in gray matter of Alzheimer's disease brain. Unmasking in 1mM EDTA (pH8.0) in a pressure cooker may be required for up to 5 minutes in order for this APP-228 to work optimally.

A-Beta proteolysis by TTR is KPI-sensitive.
A- A-Beta incubated with TTR (A-Beta+TTR) shows a weaker A-Beta monomer band as compared to A-Beta alone (A-Beta), indicative of proteolysis, as analyzed by SDS-PAGE electrophoresis followed by western blot. Pre-incubation of TTR with pefabloc (A-Beta+(TTR+pefabloc)) and with an αAPP peptide containing the KPI domain (A-Beta+(TTR+KPI+−APP)) inhibits TTR proteolytic activity, whereas the αAPP peptide without the KPI domain (A-Beta+(TTR+KPI−−APP)) facilitates proteolysis. B- % of inhibition of TTR proteolysis by quantification of band intensity in A. C- Ultrastructural analysis by TEM of preparations incubated for 15 hours, as described in Materials and Methods. TTR inhibited A-Beta aggregation as compared with A-Beta incubated alone (upper panels). Pre-incubation of TTR with αAPP peptide containing the KPI domain (A-Beta+(TTR+KPI+−APP)) abrogated TTR ability to avoid A-Beta aggregation, whereas αAPP lacking the KPI domain (A-Beta+(TTR+KPI−−APP)) did not affected TTR activity (lower panels). Scale bar=500 nm. PLoS ONE. 2008; 3(8): e2899. Published online 2008 August 6. doi: 10.1371/journal.pone.0002899.