Role of 3-O-sulfated heparan sulfates in tau pathology in Alzheimer’s disease

Abstract

Tau protein aggregation is a hallmark pathology in Alzheimer’s disease (AD), mediated by interactions with heparan sulfates (HS) particularly 3-O-sulfated modifications generated by a family of seven enzymes called heparan sulfate 3 O-sulfotransferases (HS3STs). In AD particularly HS3ST2 has been established in tau pathology. However, the contribution of other HS3ST’s (1, 2, 4 and 5) expressed in the brain remain unclear. This study, part of the TAuopathies Specialized sulfotransferases (TASSU) project, aimed to establish and validate robust experimental methodologies for investigating HS3ST function in tau pathology. Using transfected HEK293 cells co-expressing tau with individual HS3ST enzymes were analyzed sarkosyl fractionation followed by quantitative western blot (WB) to separate soluble from insoluble tau species. In parallel, we validate the extraction and quantification of cellular glycosaminoglycans with the dimethyl-methylene blue (DMMB) based assay This work establishes validated, reproducible robust methodologies to study tau aggregation and DMMB quantification. By providing a reliable methodological framework, these findings support the TASSU project’s objectives to elucidate the mechanistic role of HS3ST enzymes in tau-mediated neurodegeneration in AD and related tauopathies.