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Characterization of mAb AP422, a novel phosphorylation-dependent monoclonal antibody against tau protein
M Hasegawa1, R Jakes, R A Crowther
1MRC Laboratory of Molecular Biology, Cambridge, UK.
Abstract:
A monoclonal antibody (AP422) specific for phosphoserine 422 in microtubule-associated protein tau has been produced. It strongly labels paired helical filament (PHF) tau from Alzheimer's disease brain in a phosphorylation-dependent manner. By contrast, AP422 only labels a small fraction of fetal tau and a very small fraction of tau from adult brain. The amount of tau phosphorylated at Ser-422 in normal brain is minor relative to that phosphorylated at sites recognized by other phosphorylation-dependent anti-tau antibodies of known epitope. It follows that AP422 is the most specific anti-tau antibody available for detecting the neurofibrillary lesions of Alzheimer's disease. We also show that Ser-422 in tau is a good in vitro substrate for mitogen-activated protein kinase, but not for glycogen synthase kinase-3 or neuronal cdc2-like kinase.
Insights
A new antibody, AP422, specifically targets phosphorylated tau protein (PHF-tau) found in Alzheimer's disease brains. This makes AP422 a highly specific tool for detecting Alzheimer's-related neurofibrillary tangles.
Area of Science:
- Neuroscience
- Biochemistry
- Immunology
Background:
- Microtubule-associated protein tau (tau) is implicated in neurodegenerative diseases.
- Abnormal tau phosphorylation forms neurofibrillary tangles (NFTs), a hallmark of Alzheimer's disease (AD).
- Specific antibodies are crucial for detecting pathological tau species.
Purpose of the Study:
- To produce and characterize a novel monoclonal antibody, AP422.
- To assess the specificity of AP422 for phosphorylated tau (PHF-tau) in Alzheimer's disease.
- To evaluate the utility of AP422 in detecting neurofibrillary lesions.
Main Methods:
- Production of a monoclonal antibody (AP422) targeting phosphoserine 422 in tau.
- Immunohistochemical labeling of tau from Alzheimer's disease, fetal, and adult brains.
- In vitro kinase assays to determine phosphorylation substrates.
Main Results:
- AP422 strongly labels PHF-tau from Alzheimer's disease brains in a phosphorylation-dependent manner.
- AP422 shows minimal labeling of tau from fetal and adult normal brains.
- Ser-422 is a preferred in vitro phosphorylation site for mitogen-activated protein kinase (MAPK).
Conclusions:
- AP422 is a highly specific antibody for detecting Alzheimer's disease-associated phosphorylated tau.
- AP422 represents a valuable tool for diagnosing and studying Alzheimer's disease pathology.
- Serine 422 phosphorylation of tau is mediated by MAPK, providing insights into disease mechanisms.