The cellular Pax-Hox-helix connection.
Basic helix-loop-helix (bHLH) transcription factors are important regulators of lineage determination during embryogenesis. Initial experiments in Drosophila showed that early neural selection and specification are dependent on atonal (ato) and members of the achaete-scute complex (as-c). In mammals, transcription factors homologous to as-c and ato are causally involved during development of organs throughout the body. Development of subsets of lineages in intestine, stomach, pancreas, lung, thyroid and placenta have been shown to be regulated by members of the as-c and ato families. These functional studies show that an individual bHLH transcription factor can regulate multiple developmental processes throughout the mammalian body, which implicates that extant as-c and ato transcription factors play a distinct function dependent on their cellular context. Based on the synergistic activation of the insulin, POMC and Pax4 promotors by bHLH and homeobox (Hox) protein complexes, we hypothesize that the underlying cellular function-modulating factors include members of the Hox and paired box (Pax) multigene families. These examples indicate that unique combinations of bHLH and Hox proteins, mediated by protein-protein interactions, might be responsible for activating cell-specific sets of target genes.
Westerman
Bart A
BA
Department of Clinical Chemistry, VU University Medical Center, de Boelelaan 1117, PO Box 7057, 1081 HV 1007 MB, Amsterdam, The Netherlands. a.westerman@vumc.nl
Murre
Cornelis
C
Oudejans
Cees B M
CB
D000818:Animals; D019070:Cell Lineage; D004268:DNA-Binding Proteins / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D018257:Helix-Loop-Helix Motifs / Q000502:physiology*; D018398:Homeodomain Proteins / Q000502:physiology*; D008322:Mammals; D008954:Models, Biological; D005810:Multigene Family; D009420:Nervous System / Q000196:embryology; D009928:Organ Specificity; D014157:Transcription Factors / Q000502:physiology
D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D014157:Transcription Factors