title: Getting your head around Hex and Hesx1: forebrain formation in mouse.
abstract: An increasing amount of evidence suggests that in mouse there are two signalling centres required for the formation of a complete neural axis: the anterior visceral endoderm (AVE), and the node and its derivatives. Embryological and genetic studies suggest that the AVE has a head-inducing activity. In contrast, the node appears to act first as a head inducer in synergy with the AVE initiating anterior neural patterning at early stages of mouse development, and later, node derivatives are necessary for maintenance and embellishment of anterior neural character. Hex and Hesx1 are homeobox genes that are expressed in relevant tissues involved in anterior patterning. The analysis of the Hex and Hesx1 mutant mice has revealed that the lack of these genes has little or no effect on the early steps of anterior neural induction. However, both genes are required subsequently for the proper expansion of the forebrain region. We suggest that disturbance in the specification of an Fgf8 signalling centre in the anterior neural ridge may account for the anterior defects observed in these mutants.
authors: Division of Mammalian Development, National Institute for Medical Research, London, England.
authors: J P
authors: JP
authors: Martinez-Barbera
authors: R S
authors: RS
authors: Beddington
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D019521:Body Patterning / Q000235:genetics; D004627:Embryonic Induction; D004707:Endoderm / Q000166:cytology; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D016548:Prosencephalon / Q000196:embryology*; D012097:Repressor Proteins; D015398:Signal Transduction; D000072056:Transcription Factor HES-1; D014157:Transcription Factors
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors; D018398:Homeodomain Proteins; D012097:Repressor Proteins; D000072056:Transcription Factor HES-1; D014157:Transcription Factors; C496457:Fgf8 protein, mouse; C489736:HESX1 protein, human; C489734:Hes1 protein, mouse; C489733:Hesx1 protein, mouse; C513080:Hhex protein, mouse