12 research outputs found
Recommended from our members
belladonna/(lhx2) is required for neural patterning and midline axon guidance in the zebrafish forebrain
Some of the earliest axon pathways to form in the vertebrate forebrain are established as commissural and retinal axons cross t he midline of the diencephalon and telencephalon. To better understand axon guidance in the forebrain, we characterized the zebrafish belladonna ( bel ) mutation, which disrupts commissural and retinal axon guidance in the forebrain. Using a positional cloning strategy, we determined that the bel locus encodes zebrafish Lhx2, a lim-homeodomain transcription factor expressed in the brain, eye and fin buds. We show that bel(lhx2) function is required for patterning in the ventral forebrain and eye, and that loss of bel function leads to alterations in regulatory gene expression, perturbations in axon guidance factors, and the absence of an optic chiasm and forebrain commissures. Our analysis reveals new roles for lhx2 in midline axon guidance, forebrain patterning and eye morphogenesis
miR-181a/b control the assembly of visual circuitry by regulating retinal axon specification and growth
Connectivity and function of neuronal circuitry require the correct specification and growth of axons and dendrites. Here we identify the microRNAs miR-181a and miR-181b as key regulators of retinal axon specification and growth. Loss of miR-181a/b in medaka fish (Oryzias latipes) failed to consolidate amacrine cell processes into axons and delayed the growth of retinal ganglion cell (RGC) axons. These alterations were accompanied by defects in visual connectivity and function. We demonstrated that miR-181a/b exert these actions through negative modulation of MAPK/ERK signaling that in turn leads to RhoA reduction and proper neuritogenesis in both amacrine cells and RGCs via local cytoskeletal rearrangement. Our results identify a new pathway for axon specification and growth unraveling a crucial role of miR-181a/b in the proper establishment of visual system connectivity and function