1. Background of Technology
1.1. Clinical implication of Tau modification in Alzheimer’s disease
- Clinical association of Tau hyper-phosphorylation with Alzheimer’s disease
: PHF(paired helical filament) with hyper-phosphorylated tau found in AD patients and Tauopathy
: Gsk and cdk5 kinase are responsible for Tau pathologic phosphorylation
- Clinical correlation of Tau aggregation with Alzheimer’s disease
: Tau oligomer and aggregates found in AD patients and Tauopathy
1.2. Newly being developed but not successful yet
- Active initiation of Tau modification/aggregation pathology research
: Compared to amyloid, less effort has been done. But active researches increase (2008, 2009, ICAD)
- Recent initiation with High through-put screening for Tau aggregation modulator
: Development for cdk5 Inhibitors and screening of Tau aggregation blocker (2008, 2009 ICAD)
1.3. Limited screening assays and a few available targets for drug development
- A few targets, including GSK3b and cdk5/p25
: Most laboratories or Biotech Inc. are working on a few targets known in public domain for tauopathy, such as GSK3b and cdk5. There are not many targets for drug development.
-Competitive new targets needed
: More targets are required, including upstream of GSK or cdk5 for Tau modification and aggregation etc.
2.1. Unique establishment of modified-Tau cell-based assay for high contents screening
- We established Tau aggregation cell-based assay and prepared cDNA library for screening
: Most laboratories have used in vitro aggregation assays using purified Tau for compound screening because there is little available cell-based assay system. We established modified Tau-based cell assay for tau aggregation. In contrast to other genome-wide screening, we collected human cDNA in a mammalian expression vector (>17,000) for gain-of-screening (Fig. 1).
-Successful high-content screening for gain-of-function using cDNA
: From high-content screening using cDNA (>4,000 cDNA), we successfully isolated new genes and pathways which regulate Tau aggregation and hyper-phosphorylation.
2.2. R receptor: Isolation of new pathway (genes) for Tau phosphorylation/aggregation
- In vitro characterization: Role of R receptor in Tau hyper-phosphorylation/aggregation
: Expression or knockdown of R receptor modulates Tau phosphorylation/aggregation in neuronal cells. In addition, R receptor affects neuronal cell’s viability.
-R receptor as an upstream of cdk5 for Tau hyper-phosphorylation/aggregation
: R receptor seems to work at an upstream of cdk5 in cell level.
- in vivo characterization for neurotoxicity, providing proof of concept
: In fly rough eye model, R receptor increases Tau-induced neuronal degeneration, while dominant negative mutant rescues the toxic effects induced by Tau.
(* In R receptor knockout mice, R receptor seems to be viable but looks better smart).