Abstract
ABSTRACTSynapses are particularly vulnerable in many neurodegenerative diseases and often the first to degenerate, for example in the motor neuron disease spinal muscular atrophy (SMA). Compounds that can counteract synaptic destabilisation are rare. Here, we describe an automated screening paradigm in zebrafish for small-molecule compounds that stabilize the neuromuscular synapse in vivo. We make use of a mutant for the axonal C-type lectin chondrolectin (chodl), one of the main genes dysregulated in SMA. In chodl−/− mutants, neuromuscular synapses that are formed at the first synaptic site by growing axons are not fully mature, causing axons to stall, thereby impeding further axon growth beyond that synaptic site. This makes axon length a convenient read-out for synapse stability. We screened 982 small-molecule compounds in chodl chodl−/− mutants and found four that strongly rescued motor axon length. Aberrant presynaptic neuromuscular synapse morphology was also corrected. The most-effective compound, the adenosine uptake inhibitor drug dipyridamole, also rescued axon growth defects in the UBA1-dependent zebrafish model of SMA. Hence, we describe an automated screening pipeline that can detect compounds with relevance to SMA. This versatile platform can be used for drug and genetic screens, with wider relevance to synapse formation and stabilisation.
Highlights
Zebrafish (Danio rerio) embryos are versatile models to investigate the mechanisms of motor neuron diseases owing to the relative ease with which one can analyse the morphology and growth of the motor axons
Recent evidence shows that formation of these ‘en passant’ synapses between motor axons and muscle pioneer cells may be necessary for subsequent motor axon growth (Oprisoreanu et al, 2019)
In control embryos, motor axons typically have all grown beyond the horizontal myoseptum (HM), whearas in chodl mutants caudal primary (CaP) motor axons are mostly stalled at the HM (Oprisoreanu et al, 2019; Zhong et al, 2012)
Summary
Zebrafish (Danio rerio) embryos are versatile models to investigate the mechanisms of motor neuron diseases owing to the relative ease with which one can analyse the morphology and growth of the motor axons Secondary motor axons follow the trajectories of the primary motor neurons (Beattie et al, 2002; Myers et al, 1986; Seredick et al, 2012; Westerfield et al, 1986)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.