Trans-cellular propagation of tau pathology has been implicated in the progression of Alzheimer’s disease and other tauopathies. We previously have determined the mechanism by which tau aggregates bind the cell surface to trigger uptake via macropinocytosis. This involves direct binding of tau to heparan sulfate proteoglycans (HSPGs) on the cell surface. HSPGs are glycolipid-anchored and transmembrane core proteins that are extensively glycosylated and sulfated by a defined set of cellular enzymes. In prior published and unpublished work, we have determined that disruption of EXT1, a gene that plays a proximal role in the extension of sugar chains on HSPG core proteins, strongly inhibits tau aggregate uptake, seeding and transcellular propagation in vitro and in vivo. We hypothesize that individual HSPG synthetic genes required for tau uptake will represent viable drug targets.
Aim 1: We will individually test each of 24 genes associated with HSPG synthesis using Cas9/CRISPR-mediated gene knockout in HEK293T cells. We will confirm hits in HEK293T cells and primary cultured neurons.
Aim 2: We will test candidate genes in an in vivo model of spreading tau pathology by AAV-shRNA knockdown. If we are successful, a limited number of candidates will represent important new drug targets to block Alzheimer’s disease progression.