RRC ID 391
Author Linville A, Gumusaneli E, Chandraratna RA, Schilling TF.
Title Independent roles for retinoic acid in segmentation and neuronal differentiation in the zebrafish hindbrain.
Journal Dev. Biol.
Abstract Segmentation of the vertebrate hindbrain into rhombomeres is essential for the anterior-posterior patterning of cranial motor nuclei and their associated nerves. The vitamin A derivative, retinoic acid (RA), is an early embryonic signal that specifies rhombomeres, but its roles in neuronal differentiation within the hindbrain remain unclear. Here we have analyzed the formation of primary and secondary hindbrain neurons in the zebrafish mutant neckless (nls), which disrupts retinaldehyde dehydrogenase 2 (raldh2), and in embryos treated with retinoid receptor (RAR) antagonists. Mutation of nls disrupts secondary, branchiomotor neurons of the facial and vagal nerves, but not the segmental pattern of primary, reticulospinal neurons, suggesting that RA acts on branchiomotor neurons independent of its role in hindbrain segmentation. Very few vagal motor neurons form in nls mutants and many facial motor neurons do not migrate out of rhombomere 4 into more posterior segments. When embryos are treated with RAR antagonists during gastrulation, we observe more severe patterning defects than seen in nls. These include duplicated reticulospinal neurons and posterior expansions of rhombomere 4, as well as defects in branchiomotor neurons. However, later antagonist treatments after rhombomeres are established still disrupt branchiomotor development, suggesting that requirements for RARs in these neurons occur later and independent of segmental patterning. We also show that RA produced by the paraxial mesoderm controls branchiomotor differentiation, since we can rescue the entire motor innervation pattern by transplanting wild-type cells into the somites of nls mutants. Thus, in addition to its role in determining rhombomere identities, RA plays a more direct role in the differentiation of subsets of branchiomotor neurons within the hindbrain.
Volume 270(1)
Pages 186-99
Published 2004-6-1
DOI 10.1016/j.ydbio.2004.02.022
PII S0012160604001563
PMID 15136149
MeSH Aldehyde Oxidoreductases / genetics Aldehyde Oxidoreductases / metabolism Animals Body Patterning* Branchial Region / cytology Branchial Region / embryology Cell Differentiation / physiology* Cell Movement / physiology Neurons / cytology Neurons / physiology* Receptors, Retinoic Acid / antagonists & inhibitors Retinal Dehydrogenase Rhombencephalon / cytology Rhombencephalon / embryology* Rhombencephalon / metabolism Signal Transduction / physiology Tretinoin / metabolism* Zebrafish / anatomy & histology Zebrafish / embryology* Zebrafish / genetics
IF 2.936
Times Cited 42
Zebrafish rw0