title: Hox gene regulation and timing in embryogenesis.
abstract: Hox genes are critical regulators of embryonic development in bilaterian animals. They exhibit a unique mode of transcriptional regulation where the position of the genes along the chromosome corresponds to the time and place of their expression during development. The sequential temporal activation of these genes in the primitive streak helps determining their subsequent pattern of expression along the anterior-posterior axis of the embryo, yet the precise correspondence between these two collinear processes is not fully understood. In addition, vertebrate Hox genes evolved similar modes of regulation along secondary body axes, such as the developing limbs. We review the current understanding of the mechanisms operating during activation, maintenance and silencing of Hox gene expression in these various contexts, and discuss the evolutionary significance of their genomic organization.
authors.affiliation: Department of Epigenetics, Max-Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108 Freiburg, Germany. Electronic address: montavon@ie-freiburg.mpg.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Montavon
authors.affiliation: Institute of Molecular Biology gGmbH (IMB), Ackermannweg 4, 55128 Mainz, Germany. Electronic address: n.soshnikova@imb-mainz.de.
authors.forename: Natalia
authors.initials: N
authors.lastname: Soshnikova
mesh_terms: D000818:Animals; D002843:Chromatin / Q000235:genetics; D047108:Embryonic Development / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D005810:Multigene Family
chemical_list: D002843:Chromatin; D018398:Homeodomain Proteins
keywords: Collinearity; Enhancers; Gene clusters; Long-range interactions; Polycomb