Ets-1 transcription factor regulates glial cell regeneration and function in planarians.

Glia play multifaceted roles in nervous systems in response to injury. Depending on the species, extent of injury and glial cell type in question, glia can help or hinder the regeneration of neurons. Studying glia in the context of successful regeneration could reveal features of pro-regenerative glia that could be exploited for new human therapies.

Myelination induces axonal hotspots of synaptic vesicle fusion that promote sheath growth.

Myelination of axons by oligodendrocytes enables fast saltatory conduction. Oligodendrocytes are responsive to neuronal activity, which has been shown to induce changes to myelin sheaths, potentially to optimize conduction and neural circuit function. However, the cellular bases of activity-regulated myelination in vivo are unclear, partly due to the difficulty of analyzing individual myelinated axons over time.

PCP and Wnt pathway components act in parallel during zebrafish mechanosensory hair cell orientation.

Planar cell polarity (PCP) plays crucial roles in developmental processes such as gastrulation, neural tube closure and hearing. Wnt pathway mutants are often classified as PCP mutants due to similarities between their phenotypes. Here, we show that in the zebrafish lateral line, disruptions of the PCP and Wnt pathways have differential effects on hair cell orientations.

Adenosine receptor expression in the adult zebrafish retina.

Adenosine is an endogenous nucleoside in the central nervous system that acts on adenosine receptors. These are G protein-coupled receptors that have four known subtypes: A1, A2A, A2B, and A3 receptors. In the present study, we aimed to map the location of the adenosine receptor subtypes in adult wild-type zebrafish retina using in situ hybridization and immunohistochemistry.

Individual Neuronal Subtypes Exhibit Diversity in CNS Myelination Mediated by Synaptic Vesicle Release.

Regulation of myelination by oligodendrocytes in the CNS has important consequences for higher-order nervous system function (e.g., [1-4]), and there is growing consensus that neuronal activity regulates CNS myelination (e.

Mutation of sec63 in zebrafish causes defects in myelinated axons and liver pathology.

Mutations in SEC63 cause polycystic liver disease in humans. Sec63 is a member of the endoplasmic reticulum (ER) translocon machinery, although it is unclear how mutations in SEC63 lead to liver cyst formation in humans. Here, we report the identification and characterization of a zebrafish sec63 mutant, which was discovered in a screen for mutations that affect the development of myelinated axons.

DNA demethylase activity maintains intestinal cells in an undifferentiated state following loss of APC.

Although genome-wide hypomethylation is a hallmark of many cancers, roles for active DNA demethylation during tumorigenesis are unknown. Here, loss of the APC tumor suppressor gene causes upregulation of a DNA demethylase system and the concomitant hypomethylation of key intestinal cell fating genes. Notably, this hypomethylation maintained zebrafish intestinal cells in an undifferentiated state that was released upon knockdown of demethylase components.

Schwann cells inhibit ectopic clustering of axonal sodium channels.

The clustering of voltage-gated sodium channels at the axon initial segment (AIS) and nodes of Ranvier is essential for the initiation and propagation of action potentials in myelinated axons. Sodium channels localize to the AIS through an axon-intrinsic mechanism driven by ankyrin G, while clustering at the nodes requires cues from myelinating glia that interact with axonal neurofascin186 (Sherman et al., 2005; Dzhashiashvili et al.

alphaII-spectrin is essential for assembly of the nodes of Ranvier in myelinated axons.

Saltatory conduction in myelinated axons requires organization of the nodes of Ranvier, where voltage-gated sodium channels are prominently localized [1]. Previous results indicate that alphaII-spectrin, a component of the cortical cytoskeleton [2], is enriched at the paranodes [3, 4], which flank the node of Ranvier, but alphaII-spectrin's function has not been investigated. Starting with a genetic screen in zebrafish, we discovered in alphaII-spectrin (alphaII-spn) a mutation that disrupts nodal sodium-channel clusters in myelinated axons of the PNS and CNS.

nsf is essential for organization of myelinated axons in zebrafish.

Background: Myelinated axons are essential for rapid conduction of action potentials in the vertebrate nervous system. Of particular importance are the nodes of Ranvier, sites of voltage-gated sodium channel clustering that allow action potentials to be propagated along myelinated axons by saltatory conduction. Despite their critical role in the function of myelinated axons, little is known about the mechanisms that organize the nodes of Ranvier.

erbb3 and erbb2 are essential for schwann cell migration and myelination in zebrafish.

Background: Myelin is critical for efficient axonal conduction in the vertebrate nervous system. Neuregulin (Nrg) ligands and their ErbB receptors are required for the development of Schwann cells, the glial cells that form myelin in the peripheral nervous system. Previous studies have not determined whether Nrg-ErbB signaling is essential in vivo for Schwann cell fate specification, proliferation, survival, migration, or the onset of myelination.

The novel plant homeodomain protein rhinoceros antagonizes Ras signaling in the Drosophila eye.

The sequential specification of cell fates in the Drosophila eye requires repeated activation of the epidermal growth factor receptor (EGFR)/Ras/MAP kinase (MAPK) pathway. Equally important are the multiple layers of inhibitory regulation that prevent excessive or inappropriate signaling. Here we describe the molecular and genetic analysis of a previously uncharacterized gene, rhinoceros (rno), that we propose functions to restrict EGFR signaling in the eye.

Signal integration during development: insights from the Drosophila eye.

The Drosophila eye is a highly ordered epithelial tissue composed of approximately 750 subunits called ommatidia arranged in a reiterated hexagonal pattern. At higher resolution, observation of the constituent photoreceptors, cone cells, and pigment cells of the eye reveals a highly ordered mosaic of amazing regularity. This relatively simple organization belies the repeated requirement for spatially and temporally coordinated inputs from the Hedgehog (Hh), Wingless (Wg), Decapentaplegic (Dpp), JAK-STAT, Notch, and receptor tyrosine kinase (RTK) signaling pathways.

Biological functions of the ISWI chromatin remodeling complex NURF.

The nucleosome remodeling factor (NURF) is one of several ISWI-containing protein complexes that catalyze ATP-dependent nucleosome sliding and facilitate transcription of chromatin in vitro. To establish the physiological requirements of NURF, and to distinguish NURF genetically from other ISWI-containing complexes, we isolated mutations in the gene encoding the large NURF subunit, nurf301. We confirm that NURF is required for transcription activation in vivo.