Regulation of polyhomeotic transcription may involve local changes in chromatin activity in Drosophila

Fauvarque, Marie-Odile; Zuber, Virginie; Dura, Jean-Maurice

doi:10.1016/0925-4773(95)00412-t

Cited by 55 publications

(45 citation statements)

References 47 publications

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“…In particular, the E(z) gene was initially characterized as a PcG gene, but a detailed analysis of the mutant phenotypes re-vealed that at some spatial and temporal stages of development E(z) acts as a trxG gene (30). Similarly, PSC was found to be exceptional among the PcG members in that it appeared to have an activating effect on ph expression (16). However, we believe it to be unlikely that both PH and PSC have such an activating function.…”

Section: Discussionmentioning

confidence: 99%

The Polycomb Group Protein Complex of Drosophila melanogaster Has Different Compositions at Different Target Genes

Strutt

Paro

1997

Molecular and Cellular Biology

143

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In Drosophila the Polycomb group genes are required for the long-term maintenance of the repressed state of many developmental regulatory genes. Their gene products are thought to function in a common multimeric complex that associates with Polycomb group response elements (PREs) in target genes and regulates higherorder chromatin structure. We show that the chromodomain of Polycomb is necessary for protein-protein interactions within a Polycomb-Polyhomeotic complex. In addition, Posterior Sex Combs protein coimmunoprecipitates Polycomb and Polyhomeotic, indicating that they are members of a common multimeric protein complex. Immunoprecipitation experiments using in vivo cross-linked chromatin indicate that these three Polycomb group proteins are associated with identical regulatory elements of the selector gene engrailed in tissue culture cells. Polycomb, Polyhomeotic, and Posterior Sex Combs are, however, differentially distributed on regulatory sequences of the engrailed-related gene invected. This suggests that there may be multiple different Polycomb group protein complexes which function at different target sites. Furthermore, Polyhomeotic and Posterior Sex Combs are also associated with expressed genes. Polyhomeotic and Posterior Sex Combs may participate in a more general transcriptional mechanism that causes modulated gene repression, whereas the inclusion of Polycomb protein in the complex at PREs leads to stable silencing.

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Section: Discussionmentioning

confidence: 99%

The Polycomb Group Protein Complex of Drosophila melanogaster Has Different Compositions at Different Target Genes

Strutt

Paro

1997

Molecular and Cellular Biology

143

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“…Mutants homoor hemizygous for lesions in either one of the two units display the same phenotypes during embryonic development, suggesting that these two molecular units encode redundant functions (Dura et al, 1987). Furthermore, inactivation of one unit is transcriptionally compensated by the other, thereby maintaining a nearly wild-type level of ph product (Fauvarque et al, 1995).…”

Section: Introductionmentioning

confidence: 90%

“…Thus, ph overexpression and loss-of-function phenotypes are distinguishable, indicating that the origin of the phenotypes is probably different. ph function is necessary in somatic cells of the germarium for both their proliferation and differentiation The implication of the ph gene in ovarian somatic cells was also studied using two different loss-of-function mutations: the hypomorphic ph lac mutation, which consists of a PlacW transposon inserted in the first intron of ph-p (Fauvarque et al, 1995); and via clonal analysis of the amorphic ph 504 (noted ph 0 ) allele, which eliminates the functions of both ph-p and phd (Dura et al, 1987). The origin of the multicyst phenotype caused by ph loss-of-function mutations was characterized more precisely by analysis of the process of follicle formation in the germarium.…”

Section: Discussionmentioning

confidence: 99%

“…All other ph alleles are hypomorphic alleles. The ph lac strain was induced by PlacW-element mutagenesis and corresponds to an insertion into the proximal unit, close to the first intron-splicing site (Fauvarque et al, 1995). The A101 enhancer-trap insertion (Ruohola et al, 1991) was used for tissue-specific β-galactosidase staining of polar cells.…”

Section: Drosophila Stocksmentioning

confidence: 99%

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polyhomeoticis required for somatic cell proliferation and differentiation during ovarian follicle formation inDrosophila

et al. 2004

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The polyhomeotic (ph) gene of Drosophila is a member of the Polycomb group (Pc-G) genes, which are required for maintenance of a repressed state of homeotic gene transcription, which stabilizes cell identity throughout development. The ph gene was recovered in the course of a gain-of-function screen aimed at identifying genes with a role during ovarian follicle formation in Drosophila, a process that involves coordinated proliferation and differentiation of two cell lineages, somatic and germline. Subsequent analysis revealed that ph loss-of-function mutations lead to production of follicles with greater or fewer than the normal number of germ cells associated with reduced proliferation of somatic prefollicular cells, abnormal prefollicular cell encapsulation of germline cysts and an excess of both interfollicular stalk cells and polar cells. Clonal analysis showed that ph function for follicle formation resides specifically in somatic cells and not in the germline. This is thus the first time that a role has been shown for a Pc-G gene during Drosophila folliculogenesis. In addition, we tested mutations in a number of other Pc-G genes, and two of them, Sex combs extra (Sce) and Sex comb on midleg (Scm), also displayed ovarian defects similar to those observed for ph. Our results provide a new model system, the Drosophila ovary, in which the function of Pc-G genes, distinct from that of control of homeotic gene expression, can be explored.

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“…Therefore, we used several Gal4 drivers to induce PhGFP expression in these tissues. The level of Ph is controlled by feedback inhibition of the Ph promoter (Fauvarque et al, 1995). The PhGFP protein was able to rescue the ph 504 -null homozygous mutant and, thus, is totally competent in repression.…”

Section: Characterization Of the Fusion Proteins Used In This Studymentioning

confidence: 99%

Polycomb group protein complexes exchange rapidly in livingDrosophila

2005

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Fluorescence recovery after photobleaching (FRAP) microscopy was used to determine the kinetic properties of Polycomb group (PcG) proteins in whole living Drosophila organisms (embryos) and tissues (wing imaginal discs and salivary glands). PcG genes are essential genes in higher eukaryotes responsible for the maintenance of the spatially distinct repression of developmentally important regulators such as the homeotic genes. Their absence, as well as overexpression, causes transformations in the axial organization of the body. Although protein complexes have been isolated in vitro, little is known about their stability or exact mechanism of repression in vivo. We determined the translational diffusion constants of PcG proteins,dissociation constants and residence times for complexes in vivo at different developmental stages. In polytene nuclei, the rate constants suggest heterogeneity of the complexes. Computer simulations with new models for spatially distributed protein complexes were performed in systems showing both diffusion and binding equilibria, and the results compared with our experimental data. We were able to determine forward and reverse rate constants for complex formation. Complexes exchanged within a period of 1-10 minutes, more than an order of magnitude faster than the cell cycle time,ruling out models of repression in which access of transcription activators to the chromatin is limited and demonstrating that long-term repression primarily reflects mass-action chemical equilibria.

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Regulation of polyhomeotic transcription may involve local changes in chromatin activity in Drosophila

Cited by 55 publications

References 47 publications

The Polycomb Group Protein Complex of Drosophila melanogaster Has Different Compositions at Different Target Genes

The Polycomb Group Protein Complex of Drosophila melanogaster Has Different Compositions at Different Target Genes

polyhomeoticis required for somatic cell proliferation and differentiation during ovarian follicle formation inDrosophila

Polycomb group protein complexes exchange rapidly in livingDrosophila

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