Maintenance of the engrailed expression pattern by Polycomb group genes in Drosophila

Development ◽  
1992 ◽  
Vol 116 (3) ◽  
pp. 805-810 ◽  
Author(s):  
D. Moazed ◽  
P.H. O'Farrell
Keyword(s):  
Expression Pattern ◽  
Expression Patterns ◽  
Ectopic Expression ◽  
Polycomb Group ◽  
Homeotic Genes ◽  
Polycomb Group Genes ◽  
Sex Combs ◽  
Segment Polarity ◽  
Selector Genes ◽  
Stable Maintenance

The stable maintenance of expression patterns of homeotic genes depends on the function of a number of negative trans-regulators, termed the Polycomb (Pc) group of genes. We have examined the pattern of expression of the Drosophila segment polarity gene, engrailed (en), in embryos mutant for several different members of the Pc group. Here we report that embryos mutant for two or more Pc group genes show strong ectopic en expression, while only weak derepression of en occurs in embryos mutant for a single Pc group gene. This derepression is independent of two known activators of en expression: en itself and wingless. Additionally, in contrast to the strong ectopic expression of homeotic genes observed in extra sex combs- (esc-) mutant embryos, the en expression pattern is nearly normal in esc- embryos. This suggests that the esc gene product functions in a pathway independent of the other genes in the group. The data indicate that the same group of genes is required for stable restriction of en expression to a striped pattern and for the restriction of expression of homeotic genes along the anterior-posterior axis, and support a global role for the Pc group genes in stable repression of activity of developmental selector genes.

scholarly journals Needs and Targets for the multi sex combs Gene Product in Drosophila melanogaster

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1823-1838 ◽  
Author(s):  
Olivier Saget ◽  
Françoise Forquignon ◽  
Pedro Santamaria ◽  
Neel B Randsholt
Keyword(s):  
Drosophila Melanogaster ◽  
Ectopic Expression ◽  
Polycomb Group ◽  
Homeotic Genes ◽  
Maternal Control ◽  
Gap Gene ◽  
Sex Combs ◽  
Normal Expression ◽  
Selector Genes ◽  
Mutant Phenotypes

Abstract We have analyzed the requirements for the multi sex combs (mxc) gene during development to gain further insight into the mechanisms and developmental processes that depend on the important trans-regulators forming the Polycomb group (PcG) in Drosophila melanogaster. mxc is allelic with the tumor suppressor locus lethal (1) malignant blood neoplasm (l(1)mbn). We show that the mxc product is dramatically needed in most tissues because its loss leads to cell death after a few divisions. mxc has also a strong maternal effect. We find that hypomorphic mxc mutations enhance other PcG gene mutant phenotypes and cause ectopic expression of homeotic genes, confirming that PcG products are cooperatively involved in repression of selector genes outside their normal expression domains. We also demonstrate that the mxc product is needed for imaginal head specification, through regulation of the ANT-C gene Deformed. Our analysis reveals that mxc is involved in the maternal control of early zygotic gap gene expression previously reported for some PcG genes and suggests that the mechanism of this early PcG function could be different from the PcG-mediated regulation of homeotic selector genes later in development. We discuss these data in view of the numerous functions of PcG genes during development.

Ten different Polycomb group genes are required for spatial control of the abdA and AbdB homeotic products

Development ◽  
1992 ◽  
Vol 114 (2) ◽  
pp. 493-505 ◽  
Author(s):  
J. Simon ◽  
A. Chiang ◽  
W. Bender
Keyword(s):  
Expression Patterns ◽  
Ectopic Expression ◽  
Specific Pattern ◽  
Polycomb Group ◽  
Polycomb Group Genes ◽  
Sex Combs ◽  
Normal Expression ◽  
Sex Comb ◽  
Regulatory Dna ◽  
Pair Rule

Mutations in genes of the Polycomb (Pc) group cause abnormal segmental development due to ectopic expression of the homeotic products of the Antennapedia and bithorax complexes. Here the requirements for Pc group genes in controlling the abdA and AbdB products of the bithorax complex are described. Embryos containing mutations in the genes Polycomb (Pc), extra sex combs (esc), Enhancer of zeste [E(z)], polyhomeotic (ph), Sex comb on midleg (Scm), Polycomb-like (Pcl), Sex comb extra (Sce), Additional sex combs (Asx), Posterior sex combs (Psc) and pleiohomeotic (pho) were examined. In every case, both abdA and AbdB are expressed outside of their normal domains along the anterior-posterior (A-P) axis, consistent with these Pc group products acting in a single pathway or molecular complex. The earliest detectable ectopic expression is highest in the parasegments immediately adjacent to the normal expression boundary. Surprisingly, in the most severe Pc group mutants, the earliest ectopic AbdB is distributed in a pair-rule pattern. At all stages, ectopic abdA in the epidermis is highest along the anterior edges of the parasegments, in a pattern that mimics the normal abdA cell-specific pattern. These examples of highly patterned mis-expression show that Pc group mutations do not cause indiscriminate activation of homeotic products. We suggest that the ectopic expression patterns result from factors that normally activate abdA and AbdB only in certain parasegments, but that in Pc group mutants these factors gain access to regulatory DNA in all parasegments.

Regulation of proboscipedia in Drosophila by Homeotic Selector Genes

Genetics ◽  
2000 ◽  
Vol 156 (1) ◽  
pp. 183-194
Author(s):  
Douglas B Rusch ◽  
Thomas C Kaufman
Keyword(s):  
Expression Pattern ◽  
Regulatory Element ◽  
Polycomb Group ◽  
Accumulation Pattern ◽  
Cis Acting ◽  
Polycomb Group Genes ◽  
Gap Genes ◽  
Combined Action ◽  
Selector Genes

Abstract The gene proboscipedia (pb) is a member of the Antennapedia complex in Drosophila and is required for the proper specification of the adult mouthparts. In the embryo, pb expression serves no known function despite having an accumulation pattern in the mouthpart anlagen that is conserved across several insect orders. We have identified several of the genes necessary to generate this embryonic pattern of expression. These genes can be roughly split into three categories based on their time of action during development. First, prior to the expression of pb, the gap genes are required to specify the domains where pb may be expressed. Second, the initial expression pattern of pb is controlled by the combined action of the genes Deformed (Dfd), Sex combs reduced (Scr), cap'n'collar (cnc), and teashirt (tsh). Lastly, maintenance of this expression pattern later in development is dependent on the action of a subset of the Polycomb group genes. These interactions are mediated in part through a 500-bp regulatory element in the second intron of pb. We further show that Dfd protein binds in vitro to sequences found in this fragment. This is the first clear demonstration of autonomous positive cross-regulation of one Hox gene by another in Drosophila melanogaster and the binding of Dfd to a cis-acting regulatory element indicates that this control might be direct.

A role for mel-18, a Polycomb group-related vertebrate gene, during theanteroposterior specification of the axial skeleton

Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1513-1522 ◽  
Author(s):  
T. Akasaka ◽  
M. Kanno ◽  
R. Balling ◽  
M.A. Mieza ◽  
M. Taniguchi ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Transcriptional Repression ◽  
Ectopic Expression ◽  
Axial Skeleton ◽  
Polycomb Group ◽  
Paraxial Mesoderm ◽  
Gene Products ◽  
Polycomb Group Genes ◽  
Sex Combs ◽  
Polycomb Group Gene

Segment identity in both invertebrates and vertebrates is conferred by spatially restricted distribution of homeotic gene products. In Drosophila, the expression of Homeobox genes during embryogenesis is initially induced by segmentation gene products and then maintained by Polycomb group and Trithorax group gene products. Polycomb group gene homologs are conserved in vertebrates. Murine mel-18 and closely related bmi-1 are homologous to posterior sex combs and suppressor two of zeste. Mel-18 protein mediates a transcriptional repression via direct binding to specific DNA sequences. To gain further insight into the function of Mel-18, we have inactivated the mel-18 locus by homologous recombination. Mice lacking mel-18 survive to birth and die around 4 weeks after birth after exhibiting strong growth retardation. Similar to the Drosophila posterior sex combs mutant, posterior transformations of the axial skeleton were reproducibly observed in mel-18 mutants. The homeotic transformations were correlated with ectopic expression of Homeobox cluster genes along the anteroposterior axis in the developing paraxial mesoderm. Surprisingly, mel-18-deficient phenotypes are reminiscent of bmi-1 mutants. These results indicate that the vertebrate Polycomb group genes mel-18 and bmi-1, like Drosophila Polycomb group gene products, might play a crucial role in maintaining the silent state of Homeobox gene expression during paraxial mesoderm development.

scholarly journals Interactions of polyhomeotic with Polycomb group genes of Drosophila melanogaster.

Genetics ◽  
1994 ◽  
Vol 138 (4) ◽  
pp. 1151-1162 ◽  
Author(s):  
N N Cheng ◽  
D A Sinclair ◽  
R B Campbell ◽  
H W Brock
Keyword(s):  
Synergistic Effects ◽  
Polycomb Group ◽  
Mass Action ◽  
Temperature Sensitive ◽  
Homeotic Genes ◽  
Phenotypic Analysis ◽  
Group Function ◽  
Polycomb Group Genes ◽  
Multimeric Complex ◽  
Sex Combs

Abstract The Polycomb (Pc) group genes of Drosophila are negative regulators of homeotic genes, but individual loci have pleiotropic phenotypes. It has been suggested that Pc group genes might form a regulatory hierarchy, or might be members of a multimeric complex that obeys the law of mass action. Recently, it was shown that polyhomeotic (ph) immunoprecipitates in a multimeric complex that includes Pc. Here, we show that duplications of ph suppress homeotic transformations of Pc and Pcl, supporting a mass-action model for Pc group function. We crossed ph alleles to all members of the Polycomb group, and to E(Pc) and Su(z)2 to look for synergistic effects. We observed extragenic noncomplementation between ph503 and Pc, Psc1 and Su(z)2(1) in females, and between ph409 and Sce1, ScmD1 and E(z)1 mutations in males, suggesting that these gene products might interact directly with ph. Males hemizygous for a temperature-sensitive allele, ph2, are lethal when heterozygous with mutants in Asx, Pc, Pcl, Psc, Sce and Scm, and with E(Pc) and Su(z)2. Mutations in trithorax group genes were not able to suppress the lethality of ph2/Y; Psc1/+ males. ph2 was not lethal with extra sex combs, E(z), super sex combs (sxc) or l(4)102EFc heterozygotes, but did cause earlier lethality in embryos homozygous for E(z), sxc and l(4)102EFc. However, ph503 did not enhance homeotic phenotypes of esc heterozygotes derived from homozygous esc- mothers. We examined the embryonic phenotypes of ph2 embryos that were lethal when heterozygous or homozygous for other mutations. Based on this phenotypic analysis, we suggest that ph may perform different functions in conjunction with differing subsets of Pc group genes.

scholarly journals Analysis of maxillopedia Expression Pattern and Larval Cuticular Phenotype in Wild-Type and Mutant Tribolium

Genetics ◽  
2000 ◽  
Vol 155 (2) ◽  
pp. 721-731 ◽  
Author(s):  
Teresa D Shippy ◽  
Jianhua Guo ◽  
Susan J Brown ◽  
Richard W Beeman ◽  
Robin E Denell
Keyword(s):  
Rna Interference ◽  
Expression Pattern ◽  
Tribolium Castaneum ◽  
Expression Patterns ◽  
Ectopic Expression ◽  
Homeotic Gene ◽  
Wild Type ◽  
Double Stranded Rna ◽  
Similar Expression ◽  
Mutant Phenotypes

Abstract The Tribolium castaneum homeotic gene maxillopedia (mxp) is the ortholog of Drosophila proboscipedia (pb). Here we describe and classify available mxp alleles. Larvae lacking all mxp function die soon after hatching, exhibiting strong transformations of maxillary and labial palps to legs. Hypomorphic mxp alleles produce less severe transformations to leg. RNA interference with maxillopedia double-stranded RNA results in phenocopies of mxp mutant phenotypes ranging from partial to complete transformations. A number of gain-of-function (GOF) mxp alleles have been isolated based on transformations of adult antennae and/or legs toward palps. Finally, we have characterized the mxp expression pattern in wild-type and mutant embryos. In normal embryos, mxp is expressed in the maxillary and labial segments, whereas ectopic expression is observed in some GOF variants. Although mxp and Pb display very similar expression patterns, pb null embryos develop normally. The mxp mutant larval phenotype in Tribolium is consistent with the hypothesis that an ancestral pb-like gene had an embryonic function that was lost in the lineage leading to Drosophila.

Ectopic expression of homeotic genes caused by the elimination of the Polycomb gene in Drosophila imaginal epidermis

Development ◽  
1988 ◽  
Vol 104 (4) ◽  
pp. 713-720 ◽  
Author(s):  
A. Busturia ◽  
G. Morata
Keyword(s):  
Ectopic Expression ◽  
Homeotic Genes ◽  
Sex Combs Reduced ◽  
Hierarchical Order ◽  
Sex Combs ◽  
Morphological Patterns

The morphological patterns in the adult cuticle of Drosophila are determined principally by the homeotic genes of the bithorax and Antennapedia complexes. We find that many of these genes become indiscriminately active in the adult epidermis when the Pc gene is eliminated. By using the Pc3 mutation and various BX-C mutant combinations, we have generated clones of imaginal cells possessing different combinations of active homeotic genes. We find that, in the absence of BX-C genes, Pc- clones develop prothoracic patterns; this is probably due to the activity of Sex combs reduced which overrules Antennapedia. Adding contributions of Ultrabithorax, abdominal-A and Abdominal-B results in thoracic or abdominal patterns. We have established a hierarchical order among these genes: Antp less than Scr less than Ubx less than abd-A less than Abd-B. In addition, we show that the engrailed gene is ectopically active in Pc- imaginal cells.

Genetic interactions and dosage effects of Polycomb group genes in mice

Development ◽  
1998 ◽  
Vol 125 (18) ◽  
pp. 3543-3551 ◽  
Author(s):  
S. Bel ◽  
N. Core ◽  
M. Djabali ◽  
K. Kieboom ◽  
N. Van der Lugt ◽  
...  
Keyword(s):  
Hox Genes ◽  
Expression Patterns ◽  
Axial Skeleton ◽  
Polycomb Group ◽  
Genetic Interactions ◽  
Homeotic Gene ◽  
Polycomb Group Genes ◽  
Dosage Effects ◽  
Somitic Mesoderm ◽  
Homeotic Gene Expression

In Drosophila and mouse, Polycomb group genes are involved in the maintenance of homeotic gene expression patterns throughout development. Here we report the skeletal phenotypes of compound mutants for two Polycomb group genes bmi1 and M33. We show that mice deficient for both bmi1 and M33 present stronger homeotic transformations of the axial skeleton as compared to each single Polycomb group mutant, indicating strong dosage interactions between those two genes. These skeletal transformations are accompanied with an enhanced shift of the anterior limit of expression of several Hox genes in the somitic mesoderm. Our results demonstrate that in mice the Polycomb group genes act in synergy to control the nested expression pattern of some Hox genes in somitic mesodermal tissues during development.

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.

Evolution of the insect body plan as revealed by the Sex combs reduced expression pattern

Development ◽  
1997 ◽  
Vol 124 (1) ◽  
pp. 149-157 ◽  
Author(s):  
B.T. Rogers ◽  
M.D. Peterson ◽  
T.C. Kaufman
Keyword(s):  
Morphological Evolution ◽  
Expression Patterns ◽  
Morphological Characters ◽  
Homeotic Gene ◽  
Homeotic Genes ◽  
Cell Fates ◽  
Sex Combs Reduced ◽  
Sex Combs ◽  
Evolutionarily Conserved ◽  
Epidermal Expression

The products of the HOM/Hox homeotic genes form a set of evolutionarily conserved transcription factors that control elaborate developmental processes and specify cell fates in many metazoans. We examined the expression of the ortholog of the homeotic gene Sex combs reduced (Scr) of Drosophila melanogaster in insects of three divergent orders: Hemiptera, Orthoptera and Thysanura. Our data reflect how the conservation and variation of Scr expression has affected the morphological evolution of insects. Whereas the anterior epidermal expression of Scr, in a small part of the posterior maxillary and all of the labial segment, is found to be in common among all four insect orders, the posterior (thoracic) expression domains vary. Unlike what is observed in flies, the Scr orthologs of other insects are not expressed broadly over the first thoracic segment, but are restricted to small patches. We show here that Scr is required for suppression of wings on the prothorax of Drosophila. Moreover, Scr expression at the dorsal base of the prothoracic limb in two other winged insects, crickets (Orthoptera) and milkweed bugs (Hemiptera), is consistent with Scr acting as a suppressor of prothoracic wings in these insects. Scr is also expressed in a small patch of cells near the basitarsal-tibial junction of milkweed bugs, precisely where a leg comb develops, suggesting that Scr promotes comb formation, as it does in Drosophila. Surprisingly, the dorsal prothoracic expression of Scr is also present in the primitively wingless firebrat (Thysanura) and the leg patch is seen in crickets, which have no comb. Mapping both gene expression patterns and morphological characters onto the insect phylogenetic tree demonstrates that in the cases of wing suppression and comb formation the appearance of expression of Scr in the prothorax apparently precedes these specific functions.

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