APP Processing Assay

Background of APP Processing

Amyloid precursor protein (APP) acts an essential role in neuronal development, including neuronal protein trafficking, neurite outgrowth, synaptogenesis, transmembrane signal transduction, intercellular adhesion, etc. The sequential cleavage product of APP after cleavage proteolysis by secretase and caspase is neurotoxic small peptide amyloid β (Aβ). An important hallmark of neurodegenerative Alzheimer's disease (AD) is the overproduction or aggregation of Aβ in extracellular neuritic plaques of the brain. The APP gene is expressed on chromosome 21 in humans. The mutation of the gene encoding β-APP is one of the causes of familial AD. Besides, the main β-secretase BACE1 is the primary cause of the presence of Aβ. BACE1 knockout AD model mice have reduced Aβ levels, which rescued cholinergic dysfunction, neuronal loss, and memory deficits, but altered neurological behaviors (Zhang, 2011). Therefore, revealing the APP metabolism and processing will help the researchers to explore the therapeutics for AD. Creative Biolabs has established an APP processing assay platform to help our customers in mechanism studies and therapeutic development.

Fig.1 Schematic diagram of APP processing. (Zhang, et al., 2011)

APP Processing Assay at Creative Biolabs

The APP processing assay cell line is an in vitro model for AD that can be used to detect inhibitors that suppress the formation of the Aβ peptides including secretase activity inhibitors. Creative Biolabs provides primary neuronal cell culture models, human-induced pluripotent stem cells (iPSC)-derived neuronal cell culture models, and cell line models to meet various experimental needs. The APP processing assay provided by Creative Biolabs is generally based on a stable cell line that consistently expresses the green-fluorescent human APP. To carry out the assay, cells are cultured with target substances to assess how they affect APP processing. After the cell incubation, the nucleus is labeled with nuclear counterstain and the fluorescence of the preserved fluorescent APP vesicles appears retained in fluorescent spots using image analysis methods.

APP Processing Assay Service for APP Isoforms

APP processing assay services offered by Creative Biolabs contribute to identifying APP isoforms that are responsible for AD. The isoforms are formed due to the post-transcriptional splicing. There are three major APP isoforms, including APP695, APP751, and APP770, which contain a corresponding number of amino acids. There are two main toxic forms of APP cleavage products, Aβ40, and Aβ42 peptides. Aβ42 peptide is more essential for AD pathogenesis than Aβ40.

Revealing further detailed mechanisms of APP processing will help researchers to find inhibitors of Aβ formation and accumulation, which promote novel drug development for AD. Creative Biolabs offers comprehensive in vitro APP processing assays that enable researchers to accurately evaluate how the drug candidates influence APP processing so that they can screen promising drugs for AD. If you have the intention to learn more about APP processing in vitro assays, please don't hesitate to contact us.

Reference

1. Zhang, Y. W.; et al. (2011). APP processing in Alzheimer's disease. Molecular brain. 2011, 4(1): 1-13.