The Role of Hedgehog Signaling in the Development of the Zebrafish Visual System

Abstract

The vertebrate visual system is a region of the nervous system that is characterized by relative simplicity, and its development has hence been studied intensively, to serve as a paradigm for the rest of the central nervous system. The zebrafish model organism offers an impressive array of tools to dissect this process experimentally, and in recent years has helped to significantly deepen our understanding of the development of the visual system. A number of these studies have focused on the role of the Hedgehog family of secreted signaling molecules in eye development, and this is the main topic of this review. Hedgehog signaling plays an important role in all major steps of visual system development, starting with the regionalization of the eye primordium into proximal and distal territories, continuing with the control of cellular differentiation in the retina, and ending with the guidance of axonal projections from the retina to the optic centers of the brain.

A comparative analysis of Müller glia-mediated regeneration in the vertebrate retina

“…In the developing retina, Hh-signaling has many different roles including: (1) mitogen for retinal progenitors, (2) regulates the numbers of ganglion cells, (3) induces the formation of optic nerve glia, (4) promotes proper lamination, (5) promotes neuronal survival, (6) promotes the differentiation of the RPE, and (6) supports Müller glial differentiation (reviewed by Amato et al 2004; Stadler et al 2004; Wallace 2008; Yang 2004). Despite numerous important functioning during eye development, almost nothing is known about Hh-signaling in the mature retina and Müller glia.…”

Characterization of drCol 15a1b: A Novel Component of the Stem Cell Niche in the Zebrafish Retina

“…The following riboprobes were used: drCol 15a1b, visual system homeobox 2 (vsx2), zgc:158350, retinal homeobox gene 2 (rx2), notch1a, cbf1, drCol 18a1, atoh7 [30], shh [31], and gli 1/2 [32]. In situ probes were transcribed from their templates using the DIG RNA Labeling Kit (SP6/T7), in situ hybridizations were performed on wholemounts as previously described [33], and signal was obtained using BM purple (Roche Applied Science, Mannheim, Germany).…”

Shh directs cell‐cycle exit by activating p57Kip2 in the zebrafish retina

“…A well‐characterized context in which Hh signalling directs differentiation is the zebrafish retina (reviewed by Stadler et al , 2004). Sonic hedgehog (Shh) is expressed in a subset of retinal ganglion cells and amacrine cells, and is required for differentiation of all principal retinal cell types (Neumann & Nuesslein‐Volhard, 2000; Shkumatava et al , 2004).…”