An early phase of embryonic Dlx5 expression defines the rostral boundary of the neural plate.
Relatively little is known about the molecular events that specify the rostrocaudal axis of the neural plate. Here we show that a member of the Distal-less (Dlx) homeobox gene family, Dlx5, is one of the earliest known markers for the most rostral ectoderm, before the formation of an overt neural plate. During late gastrulation Dlx5 expression becomes localized to the anterior neural ridge, which defines the rostral boundary of the neural plate, and also extends caudolaterally, marking the region of the presumptive neural crest. Subsequently, Dlx5 is expressed in tissues (olfactory epithelium, ventral cephalic epithelium) that are believed to derive from the anterior neural ridge, based on the avian fate map. The early phase of Dlx5 expression in the anterior neural ridge and its derivatives is distinct from a later phase of expression in the ventral telencephalon and diencephalon and also appears to be unique for Dlx5 among members of the Dlx family. Another distinctive feature of Dlx5 expression is the occurrence of an alternative transcript (deltaDlx5), which encodes a truncated protein lacking the homeodomain, and represents a significant fraction of total Dlx5 transcripts at all embryonic stages that were examined. In contrast with full-length DLX5, the deltaDLX5 truncated protein is deficient in DNA-binding activity and does not interact with the homeoprotein partner MSX1. Taken together, our findings suggest that Dlx5 activity may be regulated via the expression of an alternative transcript and demonstrate that Dlx5 marks the anterior boundary of the neural plate.
Center for Advanced Biotechnology and Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
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D017398:Alternative Splicing / Q000502:physiology; D000818:Animals; D004247:DNA / Q000378:metabolism; D019143:Evolution, Molecular; D005260:Female; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D017403:In Situ Hybridization; D051957:MSX1 Transcription Factor; D051379:Mice; D008969:Molecular Sequence Data; D009432:Neural Crest / Q000196:embryology* / Q000378:metabolism; D011247:Pregnancy; D016548:Prosencephalon / Q000196:embryology* / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000502:physiology
C501120:Dlx5 protein, mouse; D018398:Homeodomain Proteins; D051957:MSX1 Transcription Factor; D014157:Transcription Factors; D004247:DNA