Zebrafish Slit2 and Slit3 Act Together to Regulate Retinal Axon Crossing at the Midline
Camila Davison1,2, Gabriela Bedó3, Flavio R Zolessi1,2
1Sección Biología Celular, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay.
Journal of Developmental Biology
|October 24, 2022
Summary
Slit-Robo signaling guides zebrafish retinal axons at the optic chiasm. Both Slit2 and Slit3 ligands, acting complementarily, are crucial for proper axon guidance, with Slit3 potentially compensating for Slit2 loss.
Area of Science:
- Neuroscience
- Developmental Biology
- Molecular Biology
Background:
- Slit-Robo signaling is essential for commissural axon midline crossing.
- In zebrafish, retinofugal axons navigate the optic chiasm to reach the tectum.
- Robo2 receptor mutants exhibit significant axon guidance defects.
Purpose of the Study:
- To investigate the collaborative role of Slit2 and Slit3 ligands in zebrafish retinofugal axon guidance at the optic chiasm.
- To elucidate the distinct functions of Slit2 and Slit3 in correcting axon turn errors.
Main Methods:
- Generation of zebrafish mutants and knockouts for Slit2 and Slit3 using CRISPR-Cas9.
- In vivo time-lapse imaging to track axon pathfinding.
- RT-qPCR analysis to assess gene expression levels.
Main Results:
- Disruption of Slit3 alone caused mild guidance defects, while combined Slit2 and Slit3 deficiency resulted in severe defects comparable to robo2 mutants.
- Time-lapse analysis revealed complementary roles for Slit2 and Slit3 in correcting axon misguidance.
- Slit3 deficiency led to a compensatory increase in Slit2 expression.
Conclusions:
- Slit2 and Slit3 act in a partially redundant and complementary manner to establish a 'repulsive channel' at the optic chiasm.
- Differential expression patterns likely contribute to their distinct roles in axon guidance.
- This study refines the understanding of Slit-Robo interactions in visual system development.
