Developing Strategies That Increase Clearance Of Mutant Ataxin-7 And Prevent Its Toxic Accumulation In Spinocerebellar Ataxia 7
Reference : PhD Yvon TROTTIER
Offer publication : April 6, 2016
Our group is interested in deciphering the pathomechanisms and developing therapeutical strategies for a group of 9 inherited
neurodegenerative disorders caused by the expansion of a polyglutamine (polyQ) motif in disease proteins. It is widely accepted that polyQ expansion conveys a toxic gain-of-function to the affected protein. This is especially attributed to its high propensity to aggregate. Yet the mechanisms through
which polyQ proteins accumulate and exert their toxic effects remain unknown. However, both the reduction of aggregation and improvement of polyQ protein degradation are of special therapeutic importance (Naiki et al., 2009, PMID: 19643812). While the mutant protein itself represents a direct target, mechanisms regulating protein homeostasis could also be manipulated to prevent toxic protein accumulation.
Among polyQ disorders, SpinoCerebellar Ataxia 7 (SCA7) is characterized by progressive cerebellar ataxia, including dysarthria and dysphagia, and cone-rod photoreceptor dystrophy with progressive central visual loss resulting in blindness in affected adults. SCA7 is caused by polyQ expansion
mutation in Ataxin-7, which accumulates in neurons, forms the so-called amyloid aggregates and leads to cerebellar and retina degeneration. Yet the mechanisms regulating the Ataxin-7 steady-state level are largely unknown.
Our project aims at identifying genes, pathways or drugs regulating the abundance of mutant Ataxin-7 in cells, with the long-term goal of manipulating these targets/drugs as potential therapy for SCA7.
To achieve this aim, the project is divided in three tasks.
First, we will generate an innovative cell-based assay expressing mutant Ataxin-7 fused to luciferase. This assay will be optimized, miniaturized and adapted for automation and high-throughput screening in collaboration with the HTS platform of IGBMC.
In the second task, the assay will be used to perform two types of screening:
i) the screening of a “druggable” genome collection of small-interfering RNA (siRNA) in order to identify genes regulating the stability of mutant Ataxin-7, as recorded by the accumulation or diminution of luciferase activity;
ii) the screening of a small collection of chemical inhibitors of polyQ aggregation, which have been recently pre-selected during a large in vitro HTS
screening of 10 000 chemical compounds including 1 200 drugs previously tested in clinical studies or already approved for other diseases by the US Food & Drug Administration (FDA). Screening of “druggable” gene siRNAs and FDA approved drugs should thus accelerate translation toward therapy development.
In the third task, the most promising targeted genes or drugs will be subsequently examined for therapeutic efficacy in organotypic brain slice cultures derived from SCA7 knock-in mice or directly in preclinical assays in SCA7 mice.
At the end of the thesis program, the PhD candidate will master a large range of biochemical and molecular biology techniques, methodologies for high-throughput and automation and for in vivo analysis of drug compounds.
- COMPETENCES SOUHAITEES :
-Interest in neurodegenerative processes and translational research
-Basic knowledge in molecular and cellular biology (with a plus with knowledge in pharmacology)
-Previous training period in a research laboratory
-autonomy and ability to work within a research group
- EXPERTISES QUI SERONT ACQUISES AU COURS DE LA FORMATION :
- technological development
- methodologies for high-throughput and automation
- ability to design and conduct experimentations (strategy choice, realization, analysis, validation)
- Communication of results through publication and scientific meeting-
- participation to writing research grant application
Application Deadline : Dec. 31, 2016