Murine genes related to the Drosophila AbdB homeotic genes are sequentially expressed during development of the posterior part of the body.

Abstract

The cloning, characterization and developmental expression patterns of two novel murine Hox genes, Hox4.6 and Hox4.7, are reported. Structural data allow us to classify the four Hox4 genes located in the most upstream (5') position in the HOX4 complex as members of a large family of homeogenes related to the Drosophila homeotic gene Abdominal B (AbdB). It therefore appears that these vertebrate genes are derived from a selective amplification of an ancestral gene which gave rise, during evolution, to the most posterior of the insect homeotic genes so far described. In agreement with the structural colinearity, these genes have very posteriorly restricted expression profiles. In addition, their developmental expression is temporally regulated according to a cranio-caudal sequence which parallels the physical ordering of these genes along the chromosome. We discuss the phylogenetic alternative in the evolution of genetic complexity by amplifying either genes or regulatory sequences, as exemplified by this system in the mouse and Drosophila. Furthermore, the possible role of 'temporal colinearity' in the ontogeny of all coelomic (metamerized) metazoans showing a temporal anteroposterior morphogenetic progression is addressed.

Characterization of the Xenopus Hox 2.4 gene and identification of control elements in its intron

“…The staining of embryo sections could be competed by preincubation with the purified Hox 2.4 fusion protein, but not by preincubation with a fusion protein containing the equivalent region of another Hox protein, Hox 3.3 (01-iver et al, 1988). While Hox 2.4 has two paralogs, Hox 3.1 and Hox 4.3, in the mouse embryo the expression pattern of these genes differs from that revealed by staining with our antibody (Awgulewitsch and Jacobs, 1990;Izpisua-Belmonte et al, 1991;see text).…”

“…That the position of a gene in the complex is reflected in the region of its expression along the anteroposterior axis of the body, combined with the sequential activation of members of the complex (Izpisua-Belmonte et al, 1991;Boncinelli et al, 1991;Leroy and De Robertis, 1992;Dekker et al, 19931, indicates that regulation occurs here on a scale above that of the individual gene, i.e., at the level of the gene complex. Evidence for this idea is seen in numerous studies with transgenic mice (Puschel et al, 1991;Tuggle et al, 1990;Bieberich et al, 1990;Renucci et al, 1992) in which even relatively large pieces of homeobox promoter DNA are not suffcient to afford the proper expression pattern to reporter genes.…”

Organization of Hox genes in ascidians: Present, past, and future

“…This phenomenon is referred to as spatial colinearity (McGinnis and Krumlauf, 1992). Also, temporal colinearity is known in some animals, where the anterior genes are expressed earlier in their development, and more posterior genes later (Izpisua-Belmonte et al, 1991). The colinearity, including spatial as well as temporal aspect, has led to the hypothesis that the physical organization of the genes on the chromosome is significant for proper morphological differentiation along the anterior-posterior axis (Duboule and Morata, 1994) and, in turn, for evolutionary changes in the animal body plan.…”

Global Analysis of Genes Regulated by HOXA10 in Decidualization Reveals a Role in Cell Proliferation.

“…HOXA10 is necessary for the development and differentitation of the reproductive tract (Izpisua-Belmonte et al, 1991). In adult female mice that are HOXA10-deficient, implantation is severely compromised and defective decidualization leads to recurrent pregnancy loss and infertility (Benson et al, 1996;Lim et al, 1999).…”