Version 2 2023-11-30, 15:41Version 2 2023-11-30, 15:41
Version 1 2023-11-28, 13:33Version 1 2023-11-28, 13:33
journal contribution
posted on 2023-11-30, 15:41authored bySehong Min, Rodrigo Mohallem, Uma K Aryal, Tamara L. Kinzer-Ursem, Jean-Christophe Rochet
A tau
variant phosphorylated on threonine 181 (pT181-tau) has been
widely investigated as a potential Alzheimer’s disease (AD)
biomarker in cerebrospinal fluid (CSF) and blood. pT181-tau is present
in neurofibrillary tangles (NFTs) of AD brains, and CSF levels of
pT181-tau correlate with the overall NFT burden. Various immunobased
analytical methods, including Western blotting and ELISA, have been
used to quantify pT181-tau in human biofluids. The reliability of
these methods is dependent on the affinity and binding specificity
of the antibodies used to measure pT181-tau levels. Although both
of these properties could, in principle, be affected by phosphorylation
within or near the antibody’s cognate antigen, such effects
have not been extensively studied. Here, we developed a biolayer interferometry
assay to determine the degree to which the affinity of pT181-tau antibodies
is altered by the phosphorylation of serine or threonine residues
near the target epitope. Our results revealed that phosphorylation
near T181 negatively affected the binding of pT181-tau antibodies
to their cognate antigen to varying degrees. In particular, two of
three antibodies tested showed a complete loss of affinity for the
pT181 target when S184 or S185 was phosphorylated. These findings
highlight the importance of selecting antibodies that have been thoroughly
characterized in terms of affinity and binding specificity, addressing
the potential disruptive effects of post-translational modifications
in the epitope region to ensure accurate biomarker quantitation.