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Homeotic gene
About: Homeotic gene is a research topic. Over the lifetime, 2505 publications have been published within this topic receiving 227334 citations.
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TL;DR: Over the past seven years, the term “homeodomain” has evolved to define a class of protein domains that have recognizable similarity to a 60 amino acid motif originally recognized in three Drosophila homeotic and segmentation proteins.
2,603 citations
TL;DR: OTTIP RNA binds the adaptor protein WDR5 directly and targets WDR 5/MLL complexes across HOXA, driving histone H3 lysine 4 trimethylation and gene transcription.
Abstract: A major question in developmental biology is how functionally related groups of genes are switched on at the right time and in the right place. Long intergenic non-coding RNAs (lincRNAs) have been implicated in both gene silencing and activation, and could be a means of long-range control of gene expression. A lincRNA termed HOTTIP that coordinates the activation of multiple 5' HOXA regulatory genes has now been identified at the 5' tip of the HOXA locus. Chromosomal looping brings HOTTIP close its target genes, where it facilitates histone H3 lysine 4 trimethylation and gene transcription. Long intergenic non-coding RNAs (lincRNAs) have been implicated in both gene silencing and activation, and could be a means for long-range control of gene expression. Here a lincRNA termed HOTTIP is identified at the 5′ tip of the HOXA locus that coordinates the activation of multiple 5′ HOXA genes. Chromosomal looping brings HOTTIP into the proximity of its target genes, where it seems to be required to facilitate histone H3 lysine 4 trimethylation and gene transcription. The genome is extensively transcribed into long intergenic noncoding RNAs (lincRNAs), many of which are implicated in gene silencing1,2. Potential roles of lincRNAs in gene activation are much less understood3,4,5. Development and homeostasis require coordinate regulation of neighbouring genes through a process termed locus control6. Some locus control elements and enhancers transcribe lincRNAs7,8,9,10, hinting at possible roles in long-range control. In vertebrates, 39 Hox genes, encoding homeodomain transcription factors critical for positional identity, are clustered in four chromosomal loci; the Hox genes are expressed in nested anterior-posterior and proximal-distal patterns colinear with their genomic position from 3′ to 5′of the cluster11. Here we identify HOTTIP, a lincRNA transcribed from the 5′ tip of the HOXA locus that coordinates the activation of several 5′ HOXA genes in vivo. Chromosomal looping brings HOTTIP into close proximity to its target genes. HOTTIP RNA binds the adaptor protein WDR5 directly and targets WDR5/MLL complexes across HOXA, driving histone H3 lysine 4 trimethylation and gene transcription. Induced proximity is necessary and sufficient for HOTTIP RNA activation of its target genes. Thus, by serving as key intermediates that transmit information from higher order chromosomal looping into chromatin modifications, lincRNAs may organize chromatin domains to coordinate long-range gene activation.
1,782 citations
TL;DR: Teleosts, the most species-rich group of vertebrates, appear to have more copies of these developmental regulatory genes than do mammals, despite less complexity in the anterior-posterior axis.
Abstract: HOX genes specify cell fate in the anterior-posterior axis of animal embryos. Invertebrate chordates have one HOX cluster, but mammals have four, suggesting that cluster duplication facilitated the evolution of vertebrate body plans. This report shows that zebrafish have seven hox clusters. Phylogenetic analysis and genetic mapping suggest a chromosome doubling event, probably by whole genome duplication, after the divergence of ray-finned and lobe-finned fishes but before the teleost radiation. Thus, teleosts, the most species-rich group of vertebrates, appear to have more copies of these developmental regulatory genes than do mammals, despite less complexity in the anterior-posterior axis.
1,730 citations
TL;DR: MiRNA172 likely acts in cell-fate specification as a translational repressor of APETALA2 in Arabidopsis flower development and results in floral organ identity defects similar to those in loss-of-function apetala2 mutants.
Abstract: Plant microRNAs (miRNAs) show a high degree of sequence complementarity to, and are believed to guide the cleavage of, their target messenger RNAs. Here, I show that miRNA172, which can base-pair with the messenger RNA of a floral homeotic gene, APETALA2, regulates APETALA2 expression primarily through translational inhibition. Elevated miRNA172 accumulation results in floral organ identity defects similar to those in loss-of-function apetala2 mutants. Elevated levels of mutant APETALA2 RNA with disrupted miRNA172 base pairing, but not wild-type APETALA2 RNA, result in elevated levels of APETALA2 protein and severe floral patterning defects. Therefore, miRNA172 likely acts in cell-fate specification as a translational repressor of APETALA2 in Arabidopsis flower development.
1,640 citations
TL;DR: Histone H3 methylated in vitro by the E(Z)/ESC complex binds specifically to Polycomb protein, which is closely associated with Polycomb binding sites on polytene chromosomes but is also found in centric heterochromatin, chromosome 4, and telomeric sites.
1,540 citations