Soluble amyloid precursor protein 770 is a novel biomarker candidate for acute coronary syndrome

<jats:p>Most <jats:styled-content style="fixed-case">A</jats:styled-content>lzheimer disease patients show deposition of amyloid β (<jats:styled-content style="fixed-case">A</jats:styled-content>β) peptide in blood vessels as well as the brain parenchyma. We previously found that vascular endothelial cells express amyloid β precursor protein (<jats:styled-content style="fixed-case">APP</jats:styled-content>) 770, a different <jats:styled-content style="fixed-case">APP</jats:styled-content> isoform from neuronal <jats:styled-content style="fixed-case">APP</jats:styled-content>695, and that they produce amyloid β peptide. We analyzed the glycosylation of <jats:styled-content style="fixed-case">APP</jats:styled-content>770 and found that <jats:italic>O</jats:italic>‐glycosylated s<jats:styled-content style="fixed-case">APP</jats:styled-content>770 is preferentially processed by proteases for <jats:styled-content style="fixed-case">A</jats:styled-content>β production. Because the soluble <jats:styled-content style="fixed-case">APP</jats:styled-content> cleavage product s<jats:styled-content style="fixed-case">APP</jats:styled-content> is considered to be a possible marker for <jats:styled-content style="fixed-case">A</jats:styled-content>lzheimer disease diagnosis, s<jats:styled-content style="fixed-case">APP</jats:styled-content>, consisting of a mixture of these variants, has been widely measured. We hypothesized that measurement of the endothelial <jats:styled-content style="fixed-case">APP</jats:styled-content>770 cleavage product in patients separately from that of neuronal <jats:styled-content style="fixed-case">APP</jats:styled-content>695 would enable us to discriminate between endothelial and neurological dysfunctions. Our recent findings, showing that the level of plasma s<jats:styled-content style="fixed-case">APP</jats:styled-content>770 is significantly higher in patients with acute coronary syndrome, raise the possibility that s<jats:styled-content style="fixed-case">APP</jats:styled-content>770 could be an indicator of endothelial dysfunction. In this review, we first describe the expression, glycosylation, and processing of <jats:styled-content style="fixed-case">APP</jats:styled-content>770, and then discuss s<jats:styled-content style="fixed-case">APP</jats:styled-content>770 as a novel biomarker candidate of acute coronary syndrome.</jats:p>