The role of Formin-2 in the Development of Rectinotectal connectivity in Danio rerio

Abstract

Cytoskeletal remodelling is imperative for the formation of precise neural circuits. Formin2 (Fmn2) is a protein known to be involved in the remodelling of both actin and microtubule cytoskeletons. Fmn2 mRNA was previously shown to be enriched in the retinal ganglion cells (RGCs) as well as in the CNS of zebrafish larvae. The zebrafish retinotectal pathway is a model system for axon guidance and retinotopic mapping. In this study, we show that morpholino-mediated knockdown of Fmn2 in zebrafish leads to defects in the architecture of the axonal projections of the RGCs to the optic tectum. We find that Fmn2 is required for the development of the optic tectum as Fmn2 morphants show reduction in the optic tectum size. In order to evaluate the functional relevance of the structural defects observed, we have evaluated the behavioural response of zebrafish to moving stimuli. Preliminary results show a trend suggesting compromised response towards this visual cue in Fmn2 morphants. Further, we have developed and standardized calcium imaging protocols that will allow us to monitor the response of the optic tectum to visual cues. Our experiments suggest that Fmn2 is required for the development of the functional visual circuitry in zebrafish.