title: RARβ regulates neuronal cell death and differentiation in the avian ciliary ganglion.
abstract: Programmed cell death during chicken ciliary ganglion (CG) development is mostly discussed as an extrinsically regulated process, guided either by the establishment of a functional balance between preganglionic and postganglionic activity or the availability of target-derived neurotrophic factors. We found that the expression of the gene coding for the nuclear retinoic acid receptor β (RARB) is transiently upregulated prior to and during the execution phase of cell death in the CG. Using retroviral vectors, the expression of RARB was knocked down during embryonic development in ovo. The knockdown led to a significant increase in CG neuron number after the cell death phase. BrdU injections and active caspase-3 staining revealed that this increase in neuron number was due to an inhibition of apoptosis during the normal cell death phase. Furthermore, apoptotic neuron numbers were significantly increased at a stage when cell death is normally completed. While the cholinergic phenotype of the neurons remained unchanged after RARB knockdown, the expression of the proneural gene Cash1 was increased, but somatostatin-like immunoreactivity, a hallmark of the mature choroid neuron population, was decreased. Taken together, these results point toward a delay in neuronal differentiation as well as cell death. The availability of nuclear retinoic acid receptor β (RARβ) and RARβ-induced transcription of genes could therefore be a new intrinsic cue for the maturation of CG neurons and their predisposition to undergo cell death.
authors: Department of Molecular Embryology, Institute of Anatomy and Cell Biology, Albert-Ludwigs-University Freiburg (ALU), Freiburg, Germany.|University of Freiburg, Faculty of Biology, Schaenzlestrasse 1, D-79104, Freiburg, Germany.
authors: Sophie
authors: S
authors: Koszinowski
authors: Institute of Molecular Medicine and Cell Research, Centre for Biochemistry und Molecular Cell Research (ZBMZ), University of Freiburg, ALU, Stefan-Meier-Str.17, Freiburg, Germany.|German Cancer Consortium (DKTK), Freiburg, Germany.|German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors: Melanie
authors: M
authors: Boerries
authors: Institute of Molecular Medicine and Cell Research, Centre for Biochemistry und Molecular Cell Research (ZBMZ), University of Freiburg, ALU, Stefan-Meier-Str.17, Freiburg, Germany.|German Cancer Consortium (DKTK), Freiburg, Germany.|German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors: Hauke
authors: H
authors: Busch
authors: Department of Molecular Embryology, Institute of Anatomy and Cell Biology, Albert-Ludwigs-University Freiburg (ALU), Freiburg, Germany.
authors: Kerstin
authors: K
authors: Krieglstein
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000502:physiology; D002478:Cells, Cultured; D002642:Chick Embryo; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D005726:Ganglia, Parasympathetic / Q000196:embryology* / Q000502:physiology*; D060850:LIM-Homeodomain Proteins / Q000378:metabolism; D055495:Neurogenesis / Q000502:physiology*; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D030161:Avian Proteins; D051792:Basic Helix-Loop-Helix Proteins; D053148:Caspase 3; D002795:Choline O-Acetyltransferase; D060850:LIM-Homeodomain Proteins; D018168:Receptors, Retinoic Acid; D014157:Transcription Factors; C099107:CASH-1 protein, Gallus gallus; C063843:insulin gene enhancer binding protein Isl-1; C082925:retinoic acid receptor beta
keywords: RARβ; ciliary ganglion; neuronal development; programmed cell death; retinoic acid