title: Hh and Wnt signaling regulate formation of olig2+ neurons in the zebrafish cerebellum.
abstract: The cerebellum, which forms from anterior hindbrain, coordinates motor movements and balance. Sensory input from the periphery is relayed and modulated by cerebellar interneurons, which are organized in layers. The mechanisms that specify the different neurons of the cerebellum and direct its layered organization remain poorly understood. Drawing from investigations of spinal cord, we hypothesized that the embryonic cerebellum is patterned on the dorsoventral axis by opposing morphogens. We tested this using zebrafish. Here we show that expression of olig2, which encodes a bHLH transcription factor, marks a distinct subset of neurons with similarities to eurydendroid neurons, the principal efferent neurons of the teleost cerebellum. In combination with other markers, olig2 reveals a dorsoventral organization of cerebellar neurons in embryos. Disruption of Hedgehog signaling, which patterns the ventral neural tube, produced a two-fold increase in the number of olig2(+) neurons. By contrast, olig2(+) neurons did not develop in embryos deficient for Wnt signaling, which patterns dorsal neural tube, nor did they develop in embryos deficient for both Hedgehog and Wnt signaling. Our data indicate that Hedgehog and Wnt work in opposition across the dorsoventral axis of the cerebellum to regulate formation of olig2(+) neurons. Specifically, we propose that Hedgehog limits the range of Wnt signaling, which is necessary for olig2(+) neuron development.
authors.affiliation: Department of Biological Sciences, Vanderbilt University, 465 21st Avenue South, Nashville, TN 37232, USA.
authors.forename: Karen A
authors.initials: KA
authors.lastname: McFarland
authors.forename: Jolanta M
authors.initials: JM
authors.lastname: Topczewska
authors.forename: Gilbert
authors.initials: G
authors.lastname: Weidinger
authors.forename: Richard I
authors.initials: RI
authors.lastname: Dorsky
authors.forename: Bruce
authors.initials: B
authors.lastname: Appel
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D064032:Calbindin 2; D002531:Cerebellum / Q000166:cytology / Q000196:embryology*; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D009024:Morphogenesis; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D000076104:Oligodendrocyte Transcription Factor 2; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D000072086:Smoothened Receptor; D014704:Veratrum Alkaloids / Q000378:metabolism; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D015027:Zebrafish / Q000033:anatomy & histology / Q000196:embryology* / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D064032:Calbindin 2; D053823:Hedgehog Proteins; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D000076104:Oligodendrocyte Transcription Factor 2; D043562:Receptors, G-Protein-Coupled; D064030:S100 Calcium Binding Protein G; D000072086:Smoothened Receptor; D014704:Veratrum Alkaloids; D051153:Wnt Proteins; D029961:Zebrafish Proteins; C501128:dkk1b protein, zebrafish; C465361:olig2 protein, zebrafish; C491021:smo protein, zebrafish; C071871:zebrin II; C000541:cyclopamine