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  • Multiomic Analysis of Neuro...
    Fernández‐Nogales, Marta; López‐Cascales, Maria Teresa; Murcia‐Belmonte, Verónica; Escalante, Augusto; Fernández‐Albert, Jordi; Muñoz‐Viana, Rafael; Barco, Angel; Herrera, Eloísa

    Advanced science, 10/2022, Letnik: 9, Številka: 29
    Journal Article

    Axon pathfinding is a key step in neural circuits formation. However, the transcriptional mechanisms regulating its progression remain poorly understood. The binary decision of crossing or avoiding the midline taken by some neuronal axons during development represents a robust model to investigate the mechanisms that control the selection of axonal trajectories. Here, to identify novel regulators of axon guidance, this work compares the transcriptome and chromatin occupancy profiles of two neuronal subpopulations, ipsilateral (iRGC) and contralateral retinal ganglion cells (cRGC), with similar functions but divergent axon trajectories. These analyses retrieved a number of genes encoding for proteins not previously implicated in axon pathfinding. In vivo functional experiments confirm the implication of some of these candidates in axonal navigation. Among the candidate genes, γ‐synuclein is identified as essential for inducing midline crossing. Footprint and luciferase assays demonstrate that this small‐sized protein is regulated by the transcription factor (TF) Pou4f1 in cRGCs. It is also shown that Lhx2/9 are specifically expressed in iRGCs and control a program that partially overlaps with that regulated by Zic2, previously described as essential for iRGC specification. Overall, the analyses identify dozens of new molecules potentially involved in axon guidance and reveal the regulatory logic behind the selection of axonal trajectories. The results presented here provide genomic screens for regarding genes and regulatory regions involved in axonal trajectory selection and offer new biological insight that may contribute to future experiments addressing how neural circuits may be rewired after damage or be useful to improve the generation of artificial neural circuits growing in brain organoids.