NAF Ataxia Research Studies Currently Underway

Kerri Carlson, PhD

University of Minnesota
Tools for SCA 1 Therapeutics

Summary: Spinocerebellar ataxia-1 type 1 (SCA 1) is a neurodegenerative, genetic disorder caused by a mutation in the SCA 1 gene. The SCA 1 gene codes for the ataxin-1 protein. Recent studies using a mouse model suggest that therapies aimed at reducing the levels of the ataxin-1 protein in cells may be effective for treating SCA1. The phosphorylation of serine 776 in the ataxin-1 protein has been linked to the stability of the ataxin-1 protein in the cell and has been demonstrated to be necessary for disease to occur. We propose that strategies aimed at preventing this phosphorylation event from occurring may be lead candidates for SCA 1 treatments. The aim of I this proposal is to identify both chemical and genetic factors that regulate ataxin-1 S776 phosphorylation. First, we have screened a library of small molecules to identify chemical modulators of S776 phosphorylation. We will perform follow up studies on lead chemicals that were identified as hits in our primary screen. In these studies we will study the specificity of each I compound for ataxin-1 phosphorylation as well as examine both their cytotoxicity and determine the effective dose of each compound. Next, we will use a secondary screen to validate compounds that we determine are highly specific inhibitors of ataxin-1 S776 phosphorylation with minimal cytotoxicity. This secondary screen will be performed using a cerebellar slice culture system. In this system thin slices of the cerebellum from a SCA 1 mouse will be exposed to our lead candidate compounds and maintained for varying amounts of time. We will then assess whether our candidate compounds continue to affect ataxin-1 S776 phosphorylation in our slice cultures. Using a cerebellar slice culture system will allow us to validate multiple hits in an environment that more closely resembles the mammalian cerebellum. Compounds that are validated using our cerebellar slice culture system will become lead compounds to follow up on in I experiments using animal models. The second part of this proposal is aimed at identifying the specific proteins (called kinases) that are involved in phosphorylating ataxin-1 S776. To accomplish this aim, we will use a technique called siRNA to decrease the expression of different kinases in the cell and then monitor the levels of ataxin-1 S776 phosphorylation. Through these experiments we will identify kinases that specifically regulate ataxin-1 S776 phosphorylation. The identification of these kinases will help us to better understand SCA1 pathology. In addition, these kinases will also become novel targets for the development of a SCA 1 therapeutic.