scholarly journals The impact of Polycomb group (PcG) and Trithorax group (TrxG) epigenetic factors in plant plasticity

2015 ◽  
Vol 208 (3) ◽  
pp. 684-694 ◽  
Author(s):  
Maria de la Paz Sanchez ◽  
Pamela Aceves-García ◽  
Emilio Petrone ◽  
Stefan Steckenborn ◽  
Rosario Vega-León ◽  
...  
Keyword(s):  
Polycomb Group ◽  
Epigenetic Factors ◽  
Trithorax Group ◽  
The Impact ◽  
Plant Plasticity

white+ Transgene Insertions Presenting a Dorsal/Ventral Pattern Define a Single Cluster of Homeobox Genes That Is Silenced by the Polycomb-group Proteins in Drosophila melanogaster

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 257-275 ◽  
Author(s):  
Sophie Netter ◽  
Marie-Odile Fauvarque ◽  
Ruth Diez del Corral ◽  
Jean-Maurice Dura ◽  
Dario Coen
Keyword(s):  
Chromatin Structure ◽  
Target Genes ◽  
Position Effect ◽  
Phenotypic Expression ◽  
Positional Information ◽  
Genomic Region ◽  
Polycomb Group ◽  
Position Effect Variegation ◽  
Trithorax Group ◽  
Clear Cut

AbstractWe used the white gene as an enhancer trap and reporter of chromatin structure. We collected white+ transgene insertions presenting a peculiar pigmentation pattern in the eye: white expression is restricted to the dorsal half of the eye, with a clear-cut dorsal/ventral (D/V) border. This D/V pattern is stable and heritable, indicating that phenotypic expression of the white reporter reflects positional information in the developing eye. Localization of these transgenes led us to identify a unique genomic region encompassing 140 kb in 69D1–3 subject to this D/V effect. This region contains at least three closely related homeobox-containing genes that are constituents of the iroquois complex (IRO-C). IRO-C genes are coordinately regulated and implicated in similar developmental processes. Expression of these genes in the eye is regulated by the products of the Polycomb -group (Pc-G) and trithorax-group (trx-G) genes but is not modified by classical modifiers of position-effect variegation. Our results, together with the report of a Pc -G binding site in 69D, suggest that we have identified a novel cluster of target genes for the Pc-G and trx-G products. We thus propose that ventral silencing of the whole IRO-C in the eye occurs at the level of chromatin structure in a manner similar to that of the homeotic gene complexes, perhaps by local compaction of the region into a heterochromatin-like structure involving the Pc-G products.

The Drosophila Polycomb-group gene Enhancer of zeste contains a region with sequence similarity to trithorax

1993 ◽  
Vol 13 (10) ◽  
pp. 6357-6366
Author(s):  
R S Jones ◽  
W M Gelbart
Keyword(s):  
Amino Acids ◽  
Sequence Similarity ◽  
Protein Product ◽  
Polycomb Group ◽  
Acute Leukemias ◽  
Trithorax Group ◽  
Acid Protein ◽  
Enhancer Of Zeste ◽  
Gene Enhancer ◽  
Carboxy Terminal

As is typical of Polycomb-group loci, the Enhancer of zeste [E(z)] gene negatively regulates the segment identity genes of the Antennapedia (ANT-C) and Bithorax (BX-C) gene complexes. A second class of loci, collectively known as the trithorax group, plays an antagonistic role as positive regulators of the ANT-C and BX-C genes. Molecular analysis of the E(z) gene predicts a 760-amino-acid protein product. A region of 116 amino acids near the E(z) carboxy terminus is 41.2% identical (68.4% similar) with a carboxy-terminal region of the trithorax protein. This portion of the trithorax protein is part of a larger region previously shown to share extensive homology with a human protein (ALL-1/Hrx) that is implicated in acute leukemias. Over this same 116 amino acids, E(z) and ALL-1/Hrx are 43.9% identical (68.4% similar). Otherwise, E(z) is not significantly similar to any previously described proteins. As this region of sequence similarity is shared by two proteins with antagonistic functions, we suggest that it may comprise a domain that interacts with a common target, either nucleic acid or protein. Opposite effects on transcription might then be determined by other portions of the two proteins.

The domino gene of Drosophila encodes novel members of the SWI2/SNF2 family of DNA-dependent ATPases, which contribute to the silencing of homeotic genes

Development ◽  
2001 ◽  
Vol 128 (8) ◽  
pp. 1429-1441 ◽  
Author(s):  
M.L. Ruhf ◽  
A. Braun ◽  
O. Papoulas ◽  
J.W. Tamkun ◽  
N. Randsholt ◽  
...  
Keyword(s):  
Polytene Chromosomes ◽  
Gene Mutations ◽  
Polycomb Group ◽  
Protein Isoforms ◽  
Homeotic Genes ◽  
Loss Of Function ◽  
Trithorax Group ◽  
A Subunit ◽  
The Common ◽  
Hematopoietic Disorders

The Drosophila domino gene has been isolated in a screen for mutations that cause hematopoietic disorders. Generation and analysis of loss-of-function domino alleles show that the phenotypes are typical for proliferation gene mutations. Clonal analysis demonstrates that domino is necessary for cell viability and proliferation, as well as for oogenesis. domino encodes two protein isoforms of 3202 and 2498 amino acids, which contain a common N-terminal region but divergent C termini. The common region includes a 500 amino acid DNA-dependent ATPase domain of the SWI2/SNF2 family of proteins, which function via interaction with chromatin. We show that, although domino alleles do not exhibit homeotic phenotypes by themselves, domino mutations enhance Polycomb group mutations and counteract Trithorax group effects. The Domino proteins are present in large complexes in embryo extracts, and one isoform binds to a number of discrete sites on larval polytene chromosomes. Altogether, the data lead us to propose that domino acts as a repressor by interfering with chromatin structure. This activity is likely to be performed as a subunit of a chromatin-remodeling complex.

scholarly journals Polycomb Requires Chaperonin Containing TCP-1 Subunit 7 for Maintaining Gene Silencing in Drosophila

2021 ◽  
Vol 9 ◽  
Author(s):  
Najma Shaheen ◽  
Jawad Akhtar ◽  
Zain Umer ◽  
Muhammad Haider Farooq Khan ◽  
Mahnoor Hussain Bakhtiari ◽  
...  
Keyword(s):  
Genetic Interaction ◽  
Expression Patterns ◽  
Cell Types ◽  
Polycomb Group ◽  
Specific Gene ◽  
Cellular Memory ◽  
Trithorax Group ◽  
T Complex ◽  
Ring Complex ◽  
Active Expression

In metazoans, heritable states of cell type-specific gene expression patterns linked with specialization of various cell types constitute transcriptional cellular memory. Evolutionarily conserved Polycomb group (PcG) and trithorax group (trxG) proteins contribute to the transcriptional cellular memory by maintaining heritable patterns of repressed and active expression states, respectively. Although chromatin structure and modifications appear to play a fundamental role in maintenance of repression by PcG, the precise targeting mechanism and the specificity factors that bind PcG complexes to defined regions in chromosomes remain elusive. Here, we report a serendipitous discovery that uncovers an interplay between Polycomb (Pc) and chaperonin containing T-complex protein 1 (TCP-1) subunit 7 (CCT7) of TCP-1 ring complex (TRiC) chaperonin in Drosophila. CCT7 interacts with Pc at chromatin to maintain repressed states of homeotic and non-homeotic targets of PcG, which supports a strong genetic interaction observed between Pc and CCT7 mutants. Depletion of CCT7 results in dissociation of Pc from chromatin and redistribution of an abundant amount of Pc in cytoplasm. We propose that CCT7 is an important modulator of Pc, which helps Pc recruitment at chromatin, and compromising CCT7 can directly influence an evolutionary conserved epigenetic network that supervises the appropriate cellular identities during development and homeostasis of an organism.

E(z): a polycomb group gene or a trithorax group gene?

Development ◽  
1996 ◽  
Vol 122 (7) ◽  
pp. 2189-2197 ◽  
Author(s):  
D. LaJeunesse ◽  
A. Shearn
Keyword(s):  
Polycomb Group ◽  
Bithorax Complex ◽  
Trithorax Group ◽  
Polycomb Group Genes ◽  
Enhancer Of Zeste ◽  
Selector Genes ◽  
Homeotic Selector Genes ◽  
Polycomb Group Gene ◽  
Anterior Posterior ◽  
Homeotic Selector

The products of the Polycomb group of genes are cooperatively involved in repressing expression of homeotic selector genes outside of their appropriate anterior/posterior boundaries. Loss of maternal and/or zygotic function of Polycomb group genes results in the ectopic expression of both Antennapedia Complex and Bithorax Complex genes. The products of the trithorax group of genes are cooperatively involved in maintaining active expression of homeotic selector genes within their appropriate anterior/posterior boundaries. Loss of maternal and/or zygotic function of trithorax group genes results in reduced expression of both Antennapedia Complex and Bithorax Complex genes. Although Enhancer of zeste has been classified as a member of the Polycomb group, in this paper we show that Enhancer of zeste can also be classified as a member of the trithorax group. The requirement for Enhancer of zeste activity as either a trithorax group or Polycomb group gene depends on the homeotic selector gene locus as well as on spatial and temporal cues.

Maintenance of the active and inactive states

2019 ◽  
pp. 80-92
Author(s):  
John C. Lucchesi
Keyword(s):  
Transcriptional Repression ◽  
Homologous Chromosome ◽  
Regulatory Region ◽  
Histone H3 ◽  
Epigenetic Modifications ◽  
Polycomb Group ◽  
Histone H2a ◽  
Trithorax Group ◽  
Non Coding Rnas ◽  
Somatic Pairing

The maintenance of a gene in an active or inactive state is carried out by epigenetic modifications of the histones and of the DNA itself. Two major classes of complexes (PRC1 and PRC2), containing Polycomb group (PcG) proteins mediate transcriptional repression. PRC2 trimethylates histone H3 at lysine 27, a modification that attracts PRC1 leading to the ubiquitination of histone H2A. Variant PRC1 complexes can be targeted first, and mono-ubiquitinated histone H2A recruits PRC2 complexes that serve as the target for canonical PRC1 complexes. PRC2 can be targeted to sites of repression by associating with long non-coding RNAs. Trithorax group (TrxG) proteins form complexes that counteract PcG-mediated repression. Some subunits of these complexes maintain and enhance transcription by carrying out different lysine methylations (H3K4me, H3K36me and H3K79me) that are associated with active gene function; other subunits remodel chromatin by displacing and repositioning nucleosomes. Additional effects on transcription are transvections, whereby somatic pairing allows the regulatory region of one allele of a gene to influence the activity of the promoter of the allele on the homologous chromosome

scholarly journals Dynamic Competition of Polycomb and Trithorax in Transcriptional Programming

2020 ◽  
Vol 89 (1) ◽  
pp. 235-253 ◽  
Author(s):  
Mitzi I. Kuroda ◽  
Hyuckjoon Kang ◽  
Sandip De ◽  
Judith A. Kassis
Keyword(s):  
Transcription Factor ◽  
Histone Modifications ◽  
Dna Sequences ◽  
Normal Development ◽  
Polycomb Group ◽  
Cell Type ◽  
Trithorax Group ◽  
Cell Type Specific ◽  
Chromatin Proteins ◽  
Regulatory Potential

Predicting regulatory potential from primary DNA sequences or transcription factor binding patterns is not possible. However, the annotation of the genome by chromatin proteins, histone modifications, and differential compaction is largely sufficient to reveal the locations of genes and their differential activity states. The Polycomb Group (PcG) and Trithorax Group (TrxG) proteins are the central players in this cell type–specific chromatin organization. PcG function was originally viewed as being solely repressive and irreversible, as observed at the homeotic loci in flies and mammals. However, it is now clear that modular and reversible PcG function is essential at most developmental genes. Focusing mainly on recent advances, we review evidence for how PcG and TrxG patterns change dynamically during cell type transitions. The ability to implement cell type–specific transcriptional programming with exquisite fidelity is essential for normal development.

scholarly journals Differential roles of trithorax protein MLL-1 in regulating neuronal Ion channels

2021 ◽  
Vol 5 (2) ◽  
Author(s):  
Dave Sonya ◽  
Zhou An
Keyword(s):  
Ion Channels ◽  
Potassium Channel ◽  
Polycomb Group ◽  
Channel Activity ◽  
Sodium Currents ◽  
Trithorax Group ◽  
Channel Protein ◽  
Trxg Protein ◽  
First Time ◽  
Potassium Channel Activity

Repressive regulation of potassium channel genes by Polycomb group (PcG) proteins contributes to PcG protein-mediated neuroprotection against neuronal ischemic injury, as seen in an ischemic stroke. Here we asked the question whether Trithorax group (TrxG) proteins, the antagonistic partners of PcG proteins (i.e, epigenetic activators targeting the same genes) may also regulate potassium channels. Results of patch-clamp studies on cultured neuronal cells showed that inhibition of TrxG protein MLL-1 led to an increase in potassium channel activity, an unexpected effect for a presumed gene activator. In contrast, decreased sodium currents were observed with MLL-1 inhibition. Increased or decreased levels of potassium channel protein Kv2.1 or sodium channel protein Nav1.2, respectively, were seen with MLL-1 inhibition, as determined by immunocytochemistry. These results, for the first time, demonstrate an involvement of TrxG protein MLL-1 in regulating neuronal ion channels, potentially repressing potassium channel genes.

scholarly journals A community survey on knowledge of the impact of environmental and epigenetic factors on health and disease

2016 ◽  
Vol 136 (6) ◽  
pp. 345-352 ◽  
Author(s):  
Marian Miller ◽  
Banita Bailey ◽  
Vinothini Govindarajah ◽  
Linda Levin ◽  
Traci Metzger ◽  
...  
Keyword(s):  
Community Survey ◽  
Epigenetic Factors ◽  
Health And Disease ◽  
The Impact
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