Regulation of neuronal lineage decisions by the HES-related bHLH protein REF-1.
Members of the HES subfamily of bHLH proteins play crucial roles in neural patterning via repression of neurogenesis. In C. elegans, loss-of-function mutations in ref-1, a distant nematode-specific member of this subfamily, were previously shown to cause ectopic neurogenesis from postembryonic lineages. However, while the vast majority of the nervous system in C. elegans is generated embryonically, the role of REF-1 in regulating these neural lineage decisions is unknown. Here, we show that mutations in ref-1 result in the generation of multiple ectopic neuron types derived from an embryonic neuroblast. In wild-type animals, neurons derived from this sublineage are present in a left/right symmetrical manner. However, in ref-1 mutants, while the ectopically generated neurons exhibit gene expression profiles characteristic of neurons on the left, they are present only on the right side. REF-1 functions in a Notch-independent manner to regulate this ectopic lineage decision. We also demonstrate that loss of REF-1 function results in defective differentiation of an embryonically generated serotonergic neuron type. These results indicate that REF-1 functions in both Notch-dependent and independent pathways to regulate multiple developmental decisions in different neuronal sublineages.
Lanjuin
Anne
A
Department of Biology, Brandeis University, Waltham, MA 02454, USA.
Claggett
Julia
J
Shibuya
Mayumi
M
Hunter
Craig P
CP
Sengupta
Piali
P
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D019521:Body Patterning; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D019070:Cell Lineage; D004268:DNA-Binding Proteins / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D009154:Mutation; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D051792:Basic Helix-Loop-Helix Proteins; D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; D051880:Receptors, Notch; D014157:Transcription Factors; C428453:ref-1 protein, C elegans