NGFN-PLUS
Modifier screen in flies overexpressing LRRK2
| Coordinator: | Univ.-Prof. Dr. med. Jörg B. Schulz | |
| Institution: | Universität Aachen | |
| Homepage: | www.neuroscience-aachen.de |
The aim of the project was, (1) to identify genetic and (2) pharmacologic modifiers of the leucine-rich repeat kinase 2 (LRRK2). Drosophila serves as a model-system, as overexpression of the fly homolog of LRRK2, dLrrk in the developing wing induces a gain-of-function (GOF) phenotype. This phenotype manifests in a disturbed pattern of the otherwise stereotypic wing veins. We know that a dynamic regulation of ERK signaling in concert with other pathways is necessary for the proper establishment of the easily monitored and highly stereotyped pattern of the wing veins. We used this dLrrk-induced wing phenotype as a non-neuronal readout for two high throughput approaches.
(1) Identifying genetic modifiers will help to understand endogenous function(s) of dLrrk/LRRK2. Moreover, knowing the cellular processes and pathway influenced by dLrrk/LRRK2 will help to understand how GOF-mutations in LRRK2 eventually lead to dopaminergic cell loss. First results strongly suggest a role of the ERK signaling cascade with respect to LRRK2s pathomechanism. However, classical epistasis could not place dLrrk in the ERK-singnaling cascade, indicating that it is not directly acting in signal transmission from EGFR via Ras, Raf to ERK. To explore dLrrk function in the complex regulatory crosstalk and feedback-loops of ERK is ongoing.
(2) The final goal of our approach and research on neurodegenerative disease in general is to cure patients suffering from these diseases. In our "drug screen" approach we are using the "fast track" directly screening chemical compounds for suppression of dLrrk-induced phenotypes. The chosen Prestwick Chemical Library® (comprised of 1120 small molecules, 100% being marketed drugs) contains active compounds, which were initially selected by Prestwick Chemical for their high diversity as well as for their known bioavailability and safety in humans. The Library was designed to reduce the risk of "low quality" hits and to reduce the cost of the initial screening. We screened the entire library using the above described wing phenotype as a readout. After several rounds of verification and confirmation, we identified 21 compounds to suppress the dLrrk-dependent wing phenotype. Thus, these compounds might inhibit dLrrk activity. Our screen should have been followed by verification of these compounds in a vertebrate model for LRRK2-induced toxicity. Unfortunately and against all expectations, there are so far no mouse models available to test the identified compounds. Nevertheless, our work might eventually open avenues for therapy in PD.
(1) Identifying genetic modifiers will help to understand endogenous function(s) of dLrrk/LRRK2. Moreover, knowing the cellular processes and pathway influenced by dLrrk/LRRK2 will help to understand how GOF-mutations in LRRK2 eventually lead to dopaminergic cell loss. First results strongly suggest a role of the ERK signaling cascade with respect to LRRK2s pathomechanism. However, classical epistasis could not place dLrrk in the ERK-singnaling cascade, indicating that it is not directly acting in signal transmission from EGFR via Ras, Raf to ERK. To explore dLrrk function in the complex regulatory crosstalk and feedback-loops of ERK is ongoing.
(2) The final goal of our approach and research on neurodegenerative disease in general is to cure patients suffering from these diseases. In our "drug screen" approach we are using the "fast track" directly screening chemical compounds for suppression of dLrrk-induced phenotypes. The chosen Prestwick Chemical Library® (comprised of 1120 small molecules, 100% being marketed drugs) contains active compounds, which were initially selected by Prestwick Chemical for their high diversity as well as for their known bioavailability and safety in humans. The Library was designed to reduce the risk of "low quality" hits and to reduce the cost of the initial screening. We screened the entire library using the above described wing phenotype as a readout. After several rounds of verification and confirmation, we identified 21 compounds to suppress the dLrrk-dependent wing phenotype. Thus, these compounds might inhibit dLrrk activity. Our screen should have been followed by verification of these compounds in a vertebrate model for LRRK2-induced toxicity. Unfortunately and against all expectations, there are so far no mouse models available to test the identified compounds. Nevertheless, our work might eventually open avenues for therapy in PD.
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