Small molecule inhibitors of CAPON-induced tau aggregation

PROJECT SUMMARY/ABSTRACT: Alzheimer's disease (AD), the most common type of dementia worldwide, is a rapidly increasing public health concern. There is an urgent need for the validation of novel targets and therapeutic strategies for AD. Given the heterogeneity of AD pathogenesis, targeting the connection between amyloid pathology, tau

pathology, and neuronal cell death in AD is gaining increasing interest as a therapeutic strategy for AD. In this context, CAPON (the carboxy-terminal PDZ ligand of neuronal nitric oxide synthase (nNOS)) has been recently identified as a novel tau-binding protein that represents a promising target to break the connection between

amyloid beta (Aβ), tau, and neurodegeneration. In tauopathy models, CAPON/tau interaction induces tau aggregation and neurodegeneration, while CAPON deficiency ameliorates AD-related pathological phenotypes. Moreover, the interaction between CAPON and nNOS mediates A-induced neurotoxicity in AD animal models. However, there are no small molecules reported to date that target the multifaceted role of

CAPON in AD pathogenesis. Our goal is to establish targeting CAPON with small molecules as a promising therapeutic strategy for AD. Our hypothesis is that CAPON-targeted small molecules with dual inhibition of CAPON/tau and CAPON/nNOS interactions can ameliorate neuronal cell death and tau pathology. Building on

our previous work focused on the discovery of small molecule modulators of tau and amyloid aggregation, we propose to screen a central nervous system (CNS)-focused chemical library of small molecules for the ability to bind CAPON using a temperature-related intensity change (TRIC)-based assay. Subsequently, we will use

time-resolved fluorescence energy transfer (TR-FRET) assays to identify small molecule CAPON binders that inhibit CAPON-centered interactions (Aim 1). We will validate the identified hits using a panel of screening assays for CAPON-targeted small molecules and perform structural optimization guided by molecular modeling

and site-directed mutagenesis (Aim 2). In Aims 2 and 3, we propose to evaluate the therapeutic potential of the optimized leads using a combination of in vitro assays and two AD mouse models. The selection of three leads for the AD mouse models will be guided by the assessment of the pharmacokinetic (PK) profiles and in vivo

target engagement of the investigated compounds. The proximal expected outcome of this work is validating the potential of small molecules to target CAPON and efficiently block CAPON/tau and CAPON/nNOS interactions in vivo. The optimized leads from this work will serve as the basis for future target-based drug

development programs and preclinical AD studies.