Transcriptional silencing by the Polycomb protein in Drosophila embryos.
PDF (4.0M)
Journal: 1995/May - EMBO Journal
ISSN: 0261-4189
PUBMED: 7720711
Abstract:
Polycomb group (Pc-G) proteins act to keep homeotic genes stably and heritably silenced during Drosophila development. Here, it is shown that Polycomb (Pc), one of the Pc-G proteins, acts as a transcriptional silencer in Drosophila embryos if tethered to reporter genes by the DNA binding domain of GAL4 (i.e. as a GAL-Pc fusion protein). The results suggest that silencing by GAL-Pc requires the C-terminal portion of Pc, but not the chromodomain. If a pulse of Gal-Pc is provided, synthetic reporter genes are repressed, though only transiently. In contrast, reporter genes containing homeotic gene sequences remain stably and heritably silenced in a Pc-G gene-dependent fashion, even when GAL-Pc is no longer present. This implies that GAL-Pc recruits Pc-G proteins to DNA and suggests that maintenance of silencing requires the anchoring of Pc-G proteins to specific cis-regulatory sequences present in homeotic genes. The extent of DNA over which the Pc-G machinery acts is quite selective, as silencing established on one enhancer does not necessarily 'spread' to a juxtaposed synthetic enhancer.
Open in
PUBMED | PMC | Google Scholar | Wikipedia
Relations:
Content
Citations
(50)
References
(92)
Chemicals
(13)
Genes
(11)
Organisms
(2)
Processes
(8)
Affiliates
(1)
Similar articles
Articles by the same authors
Discussion board
EMBO J 14(6): 1209-1220
PMID: 7720711

Transcriptional silencing by the Polycomb protein in Drosophila embryos.

Abstract

Polycomb group (Pc-G) proteins act to keep homeotic genes stably and heritably silenced during Drosophila development. Here, it is shown that Polycomb (Pc), one of the Pc-G proteins, acts as a transcriptional silencer in Drosophila embryos if tethered to reporter genes by the DNA binding domain of GAL4 (i.e. as a GAL-Pc fusion protein). The results suggest that silencing by GAL-Pc requires the C-terminal portion of Pc, but not the chromodomain. If a pulse of Gal-Pc is provided, synthetic reporter genes are repressed, though only transiently. In contrast, reporter genes containing homeotic gene sequences remain stably and heritably silenced in a Pc-G gene-dependent fashion, even when GAL-Pc is no longer present. This implies that GAL-Pc recruits Pc-G proteins to DNA and suggests that maintenance of silencing requires the anchoring of Pc-G proteins to specific cis-regulatory sequences present in homeotic genes. The extent of DNA over which the Pc-G machinery acts is quite selective, as silencing established on one enhancer does not necessarily 'spread' to a juxtaposed synthetic enhancer.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (4.0M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References.
icon of scanned page 1209
1209
icon of scanned page 1210
1210
icon of scanned page 1211
1211
icon of scanned page 1212
1212
icon of scanned page 1213
1213
icon of scanned page 1214
1214
icon of scanned page 1215
1215
icon of scanned page 1216
1216
icon of scanned page 1217
1217
icon of scanned page 1218
1218
icon of scanned page 1219
1219
icon of scanned page 1220
1220

Images in this article

Image
Image
on p.1211
Image
Image
on p.1212
Image
Image
on p.1213
Image
Image
on p.1214
Image
Image
on p.1215
Image
Image
on p.1216
Image
Image
on p.1217
Click on the image to see a larger version.

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Affolter M, Schier A, Gehring WJ. Homeodomain proteins and the regulation of gene expression. Curr Opin Cell Biol. 1990 Jun;2(3):485–495. [PubMed] [Google Scholar]
  • Akam M. The molecular basis for metameric pattern in the Drosophila embryo. Development. 1987 Sep;101(1):1–22. [PubMed] [Google Scholar]
  • Balling R, Mutter G, Gruss P, Kessel M. Craniofacial abnormalities induced by ectopic expression of the homeobox gene Hox-1.1 in transgenic mice. Cell. 1989 Jul 28;58(2):337–347. [PubMed] [Google Scholar]
  • Bienz M. Molecular mechanisms of determination in Drosophila. Curr Opin Cell Biol. 1992 Dec;4(6):955–961. [PubMed] [Google Scholar]
  • Bienz M, Saari G, Tremml G, Müller J, Züst B, Lawrence PA. Differential regulation of Ultrabithorax in two germ layers of Drosophila. Cell. 1988 May 20;53(4):567–576. [PubMed] [Google Scholar]
  • Brand AH, Perrimon N. Targeted gene expression as a means of altering cell fates and generating dominant phenotypes. Development. 1993 Jun;118(2):401–415. [PubMed] [Google Scholar]
  • Breen TR, Duncan IM. Maternal expression of genes that regulate the bithorax complex of Drosophila melanogaster. Dev Biol. 1986 Dec;118(2):442–456. [PubMed] [Google Scholar]
  • Brunk BP, Martin EC, Adler PN. Drosophila genes Posterior Sex Combs and Suppressor two of zeste encode proteins with homology to the murine bmi-1 oncogene. Nature. 1991 Sep 26;353(6342):351–353. [PubMed] [Google Scholar]
  • Bunker CA, Kingston RE. Transcriptional repression by Drosophila and mammalian Polycomb group proteins in transfected mammalian cells. Mol Cell Biol. 1994 Mar;14(3):1721–1732.[PMC free article] [PubMed] [Google Scholar]
  • Busturia A, Bienz M. Silencers in abdominal-B, a homeotic Drosophila gene. EMBO J. 1993 Apr;12(4):1415–1425.[PMC free article] [PubMed] [Google Scholar]
  • Busturia A, Morata G. Ectopic expression of homeotic genes caused by the elimination of the Polycomb gene in Drosophila imaginal epidermis. Development. 1988 Dec;104(4):713–720. [PubMed] [Google Scholar]
  • Chan CS, Rastelli L, Pirrotta V. A Polycomb response element in the Ubx gene that determines an epigenetically inherited state of repression. EMBO J. 1994 Jun 1;13(11):2553–2564.[PMC free article] [PubMed] [Google Scholar]
  • Chisaka O, Capecchi MR. Regionally restricted developmental defects resulting from targeted disruption of the mouse homeobox gene hox-1.5. Nature. 1991 Apr 11;350(6318):473–479. [PubMed] [Google Scholar]
  • Clark SG, Chisholm AD, Horvitz HR. Control of cell fates in the central body region of C. elegans by the homeobox gene lin-39. Cell. 1993 Jul 16;74(1):43–55. [PubMed] [Google Scholar]
  • DeCamillis M, Cheng NS, Pierre D, Brock HW. The polyhomeotic gene of Drosophila encodes a chromatin protein that shares polytene chromosome-binding sites with Polycomb. Genes Dev. 1992 Feb;6(2):223–232. [PubMed] [Google Scholar]
  • Desplan C, Theis J, O'Farrell PH. The sequence specificity of homeodomain-DNA interaction. Cell. 1988 Sep 23;54(7):1081–1090.[PMC free article] [PubMed] [Google Scholar]
  • Duboule D, Dollé P. The structural and functional organization of the murine HOX gene family resembles that of Drosophila homeotic genes. EMBO J. 1989 May;8(5):1497–1505.[PMC free article] [PubMed] [Google Scholar]
  • Dollé P, Duboule D. Two gene members of the murine HOX-5 complex show regional and cell-type specific expression in developing limbs and gonads. EMBO J. 1989 May;8(5):1507–1515.[PMC free article] [PubMed] [Google Scholar]
  • Fischer JA, Giniger E, Maniatis T, Ptashne M. GAL4 activates transcription in Drosophila. Nature. 1988 Apr 28;332(6167):853–856. [PubMed] [Google Scholar]
  • Franke A, DeCamillis M, Zink D, Cheng N, Brock HW, Paro R. Polycomb and polyhomeotic are constituents of a multimeric protein complex in chromatin of Drosophila melanogaster. EMBO J. 1992 Aug;11(8):2941–2950.[PMC free article] [PubMed] [Google Scholar]
  • Gaul U, Seifert E, Schuh R, Jäckle H. Analysis of Krüppel protein distribution during early Drosophila development reveals posttranscriptional regulation. Cell. 1987 Aug 14;50(4):639–647. [PubMed] [Google Scholar]
  • Giniger E, Varnum SM, Ptashne M. Specific DNA binding of GAL4, a positive regulatory protein of yeast. Cell. 1985 Apr;40(4):767–774. [PubMed] [Google Scholar]
  • González-Reyes A, Morata G. The developmental effect of overexpressing a Ubx product in Drosophila embryos is dependent on its interactions with other homeotic products. Cell. 1990 May 4;61(3):515–522. [PubMed] [Google Scholar]
  • Harding K, Levine M. Gap genes define the limits of antennapedia and bithorax gene expression during early development in Drosophila. EMBO J. 1988 Jan;7(1):205–214.[PMC free article] [PubMed] [Google Scholar]
  • Hiromi Y, Gehring WJ. Regulation and function of the Drosophila segmentation gene fushi tarazu. Cell. 1987 Sep 11;50(6):963–974. [PubMed] [Google Scholar]
  • Hoppler S, Bienz M. Specification of a single cell type by a Drosophila homeotic gene. Cell. 1994 Feb 25;76(4):689–702. [PubMed] [Google Scholar]
  • Ingham PW, Martinez-Arias A. The correct activation of Antennapedia and bithorax complex genes requires the fushi tarazu gene. Nature. 1986 Dec 11;324(6097):592–597. [PubMed] [Google Scholar]
  • Irish VF, Martinez-Arias A, Akam M. Spatial regulation of the Antennapedia and Ultrabithorax homeotic genes during Drosophila early development. EMBO J. 1989 May;8(5):1527–1537.[PMC free article] [PubMed] [Google Scholar]
  • James TC, Elgin SC. Identification of a nonhistone chromosomal protein associated with heterochromatin in Drosophila melanogaster and its gene. Mol Cell Biol. 1986 Nov;6(11):3862–3872.[PMC free article] [PubMed] [Google Scholar]
  • Jones RS, Gelbart WM. Genetic analysis of the enhancer of zeste locus and its role in gene regulation in Drosophila melanogaster. Genetics. 1990 Sep;126(1):185–199.[PMC free article] [PubMed] [Google Scholar]
  • Jones RS, Gelbart WM. The Drosophila Polycomb-group gene Enhancer of zeste contains a region with sequence similarity to trithorax. Mol Cell Biol. 1993 Oct;13(10):6357–6366.[PMC free article] [PubMed] [Google Scholar]
  • Kaufman TC, Lewis R, Wakimoto B. Cytogenetic Analysis of Chromosome 3 in DROSOPHILA MELANOGASTER: The Homoeotic Gene Complex in Polytene Chromosome Interval 84a-B. Genetics. 1980 Jan;94(1):115–133.[PMC free article] [PubMed] [Google Scholar]
  • Keegan L, Gill G, Ptashne M. Separation of DNA binding from the transcription-activating function of a eukaryotic regulatory protein. Science. 1986 Feb 14;231(4739):699–704. [PubMed] [Google Scholar]
  • Keleher CA, Redd MJ, Schultz J, Carlson M, Johnson AD. Ssn6-Tup1 is a general repressor of transcription in yeast. Cell. 1992 Feb 21;68(4):709–719. [PubMed] [Google Scholar]
  • Kenyon C. A gene involved in the development of the posterior body region of C. elegans. Cell. 1986 Aug 1;46(3):477–487. [PubMed] [Google Scholar]
  • Laurent BC, Carlson M. Yeast SNF2/SWI2, SNF5, and SNF6 proteins function coordinately with the gene-specific transcriptional activators GAL4 and Bicoid. Genes Dev. 1992 Sep;6(9):1707–1715. [PubMed] [Google Scholar]
  • Laurent BC, Treitel MA, Carlson M. Functional interdependence of the yeast SNF2, SNF5, and SNF6 proteins in transcriptional activation. Proc Natl Acad Sci U S A. 1991 Apr 1;88(7):2687–2691.[PMC free article] [PubMed] [Google Scholar]
  • Lawrence PA, Johnston P. Pattern formation in the Drosophila embryo: allocation of cells to parasegments by even-skipped and fushi tarazu. Development. 1989 Apr;105(4):761–767. [PubMed] [Google Scholar]
  • Lehmann R, Nüsslein-Volhard C. hunchback, a gene required for segmentation of an anterior and posterior region of the Drosophila embryo. Dev Biol. 1987 Feb;119(2):402–417. [PubMed] [Google Scholar]
  • Levine M, Manley JL. Transcriptional repression of eukaryotic promoters. Cell. 1989 Nov 3;59(3):405–408. [PubMed] [Google Scholar]
  • Levine M, Hafen E, Garber RL, Gehring WJ. Spatial distribution of Antennapedia transcripts during Drosophila development. EMBO J. 1983;2(11):2037–2046.[PMC free article] [PubMed] [Google Scholar]
  • Lewis EB. A gene complex controlling segmentation in Drosophila. Nature. 1978 Dec 7;276(5688):565–570. [PubMed] [Google Scholar]
  • Lufkin T, Dierich A, LeMeur M, Mark M, Chambon P. Disruption of the Hox-1.6 homeobox gene results in defects in a region corresponding to its rostral domain of expression. Cell. 1991 Sep 20;66(6):1105–1119. [PubMed] [Google Scholar]
  • Lufkin T, Mark M, Hart CP, Dollé P, LeMeur M, Chambon P. Homeotic transformation of the occipital bones of the skull by ectopic expression of a homeobox gene. Nature. 1992 Oct 29;359(6398):835–841. [PubMed] [Google Scholar]
  • Ma J, Ptashne M. A new class of yeast transcriptional activators. Cell. 1987 Oct 9;51(1):113–119. [PubMed] [Google Scholar]
  • Mann RS, Hogness DS. Functional dissection of Ultrabithorax proteins in D. melanogaster. Cell. 1990 Feb 23;60(4):597–610. [PubMed] [Google Scholar]
  • Martin EC, Adler PN. The Polycomb group gene Posterior Sex Combs encodes a chromosomal protein. Development. 1993 Feb;117(2):641–655. [PubMed] [Google Scholar]
  • Mazo AM, Huang DH, Mozer BA, Dawid IB. The trithorax gene, a trans-acting regulator of the bithorax complex in Drosophila, encodes a protein with zinc-binding domains. Proc Natl Acad Sci U S A. 1990 Mar;87(6):2112–2116.[PMC free article] [PubMed] [Google Scholar]
  • McGinnis W, Krumlauf R. Homeobox genes and axial patterning. Cell. 1992 Jan 24;68(2):283–302. [PubMed] [Google Scholar]
  • Messmer S, Franke A, Paro R. Analysis of the functional role of the Polycomb chromo domain in Drosophila melanogaster. Genes Dev. 1992 Jul;6(7):1241–1254. [PubMed] [Google Scholar]
  • Morgan BA, Izpisúa-Belmonte JC, Duboule D, Tabin CJ. Targeted misexpression of Hox-4.6 in the avian limb bud causes apparent homeotic transformations. Nature. 1992 Jul 16;358(6383):236–239. [PubMed] [Google Scholar]
  • Müller J, Bienz M. Long range repression conferring boundaries of Ultrabithorax expression in the Drosophila embryo. EMBO J. 1991 Nov;10(11):3147–3155.[PMC free article] [PubMed] [Google Scholar]
  • Müller J, Bienz M. Sharp anterior boundary of homeotic gene expression conferred by the fushi tarazu protein. EMBO J. 1992 Oct;11(10):3653–3661.[PMC free article] [PubMed] [Google Scholar]
  • Nüsslein-Volhard C, Wieschaus E. Mutations affecting segment number and polarity in Drosophila. Nature. 1980 Oct 30;287(5785):795–801. [PubMed] [Google Scholar]
  • Orlando V, Paro R. Mapping Polycomb-repressed domains in the bithorax complex using in vivo formaldehyde cross-linked chromatin. Cell. 1993 Dec 17;75(6):1187–1198. [PubMed] [Google Scholar]
  • Pankratz MJ, Hoch M, Seifert E, Jäckle H. Krüppel requirement for knirps enhancement reflects overlapping gap gene activities in the Drosophila embryo. Nature. 1989 Sep 28;341(6240):337–340. [PubMed] [Google Scholar]
  • Parkhurst SM, Harrison DA, Remington MP, Spana C, Kelley RL, Coyne RS, Corces VG. The Drosophila su(Hw) gene, which controls the phenotypic effect of the gypsy transposable element, encodes a putative DNA-binding protein. Genes Dev. 1988 Oct;2(10):1205–1215. [PubMed] [Google Scholar]
  • Paro R, Hogness DS. The Polycomb protein shares a homologous domain with a heterochromatin-associated protein of Drosophila. Proc Natl Acad Sci U S A. 1991 Jan 1;88(1):263–267.[PMC free article] [PubMed] [Google Scholar]
  • Pearce JJ, Singh PB, Gaunt SJ. The mouse has a Polycomb-like chromobox gene. Development. 1992 Apr;114(4):921–929. [PubMed] [Google Scholar]
  • Peterson CL, Herskowitz I. Characterization of the yeast SWI1, SWI2, and SWI3 genes, which encode a global activator of transcription. Cell. 1992 Feb 7;68(3):573–583. [PubMed] [Google Scholar]
  • Pillus L, Rine J. Epigenetic inheritance of transcriptional states in S. cerevisiae. Cell. 1989 Nov 17;59(4):637–647. [PubMed] [Google Scholar]
  • Qian S, Capovilla M, Pirrotta V. The bx region enhancer, a distant cis-control element of the Drosophila Ubx gene and its regulation by hunchback and other segmentation genes. EMBO J. 1991 Jun;10(6):1415–1425.[PMC free article] [PubMed] [Google Scholar]
  • Qian S, Varjavand B, Pirrotta V. Molecular analysis of the zeste-white interaction reveals a promoter-proximal element essential for distant enhancer-promoter communication. Genetics. 1992 May;131(1):79–90.[PMC free article] [PubMed] [Google Scholar]
  • Qian S, Capovilla M, Pirrotta V. Molecular mechanisms of pattern formation by the BRE enhancer of the Ubx gene. EMBO J. 1993 Oct;12(10):3865–3877.[PMC free article] [PubMed] [Google Scholar]
  • Rastelli L, Chan CS, Pirrotta V. Related chromosome binding sites for zeste, suppressors of zeste and Polycomb group proteins in Drosophila and their dependence on Enhancer of zeste function. EMBO J. 1993 Apr;12(4):1513–1522.[PMC free article] [PubMed] [Google Scholar]
  • Reinitz J, Levine M. Control of the initiation of homeotic gene expression by the gap genes giant and tailless in Drosophila. Dev Biol. 1990 Jul;140(1):57–72. [PubMed] [Google Scholar]
  • Schneuwly S, Klemenz R, Gehring WJ. Redesigning the body plan of Drosophila by ectopic expression of the homoeotic gene Antennapedia. Nature. 325(6107):816–818. [PubMed] [Google Scholar]
  • Schröder C, Tautz D, Seifert E, Jäckle H. Differential regulation of the two transcripts from the Drosophila gap segmentation gene hunchback. EMBO J. 1988 Sep;7(9):2881–2887.[PMC free article] [PubMed] [Google Scholar]
  • Scott MP, Tamkun JW, Hartzell GW., 3rd The structure and function of the homeodomain. Biochim Biophys Acta. 1989 Jul 28;989(1):25–48. [PubMed] [Google Scholar]
  • Simon J, Chiang A, Bender W, Shimell MJ, O'Connor M. Elements of the Drosophila bithorax complex that mediate repression by Polycomb group products. Dev Biol. 1993 Jul;158(1):131–144. [PubMed] [Google Scholar]
  • Shimell MJ, Simon J, Bender W, O'Connor MB. Enhancer point mutation results in a homeotic transformation in Drosophila. Science. 1994 May 13;264(5161):968–971. [PubMed] [Google Scholar]
  • Stanojević D, Hoey T, Levine M. Sequence-specific DNA-binding activities of the gap proteins encoded by hunchback and Krüppel in Drosophila. Nature. 1989 Sep 28;341(6240):331–335. [PubMed] [Google Scholar]
  • Steller H, Pirrotta V. Expression of the Drosophila white gene under the control of the hsp70 heat shock promoter. EMBO J. 1985 Dec 30;4(13B):3765–3772.[PMC free article] [PubMed] [Google Scholar]
  • Struhl G. A gene product required for correct initiation of segmental determination in Drosophila. Nature. 1981 Sep 3;293(5827):36–41. [PubMed] [Google Scholar]
  • Struhl G. Genes controlling segmental specification in the Drosophila thorax. Proc Natl Acad Sci U S A. 1982 Dec;79(23):7380–7384.[PMC free article] [PubMed] [Google Scholar]
  • Struhl G, Akam M. Altered distributions of Ultrabithorax transcripts in extra sex combs mutant embryos of Drosophila. EMBO J. 1985 Dec 1;4(12):3259–3264.[PMC free article] [PubMed] [Google Scholar]
  • Struhl G, Brower D. Early role of the esc+ gene product in the determination of segments in Drosophila. Cell. 1982 Nov;31(1):285–292. [PubMed] [Google Scholar]
  • Tautz D. Regulation of the Drosophila segmentation gene hunchback by two maternal morphogenetic centres. Nature. 1988 Mar 17;332(6161):281–284. [PubMed] [Google Scholar]
  • Muriel WJ, Cole J, Lehmann AR. Molecular analysis of ouabain-resistant mutants of the mouse lymphoma cell line L5178Y. Mutagenesis. 1987 Sep;2(5):383–389. [PubMed] [Google Scholar]
  • Treisman J, Desplan C. The products of the Drosophila gap genes hunchback and Krüppel bind to the hunchback promoters. Nature. 1989 Sep 28;341(6240):335–337. [PubMed] [Google Scholar]
  • van Lohuizen M, Frasch M, Wientjens E, Berns A. Sequence similarity between the mammalian bmi-1 proto-oncogene and the Drosophila regulatory genes Psc and Su(z)2. Nature. 1991 Sep 26;353(6342):353–355. [PubMed] [Google Scholar]
  • Vincent JP, Kassis JA, O'Farrell PH. A synthetic homeodomain binding site acts as a cell type specific, promoter specific enhancer in Drosophila embryos. EMBO J. 1990 Aug;9(8):2573–2578.[PMC free article] [PubMed] [Google Scholar]
  • Wang BB, Müller-Immergluck MM, Austin J, Robinson NT, Chisholm A, Kenyon C. A homeotic gene cluster patterns the anteroposterior body axis of C. elegans. Cell. 1993 Jul 16;74(1):29–42. [PubMed] [Google Scholar]
  • Webster N, Jin JR, Green S, Hollis M, Chambon P. The yeast UASG is a transcriptional enhancer in human HeLa cells in the presence of the GAL4 trans-activator. Cell. 1988 Jan 29;52(2):169–178. [PubMed] [Google Scholar]
  • White RA, Lehmann R. A gap gene, hunchback, regulates the spatial expression of Ultrabithorax. Cell. 1986 Oct 24;47(2):311–321. [PubMed] [Google Scholar]
  • Wilkinson DG, Bhatt S, Cook M, Boncinelli E, Krumlauf R. Segmental expression of Hox-2 homoeobox-containing genes in the developing mouse hindbrain. Nature. 1989 Oct 5;341(6241):405–409. [PubMed] [Google Scholar]
  • Winston F, Carlson M. Yeast SNF/SWI transcriptional activators and the SPT/SIN chromatin connection. Trends Genet. 1992 Nov;8(11):387–391. [PubMed] [Google Scholar]
  • Zhang CC, Bienz M. Segmental determination in Drosophila conferred by hunchback (hb), a repressor of the homeotic gene Ultrabithorax (Ubx). Proc Natl Acad Sci U S A. 1992 Aug 15;89(16):7511–7515.[PMC free article] [PubMed] [Google Scholar]
  • Zhang CC, Müller J, Hoch M, Jäckle H, Bienz M. Target sequences for hunchback in a control region conferring Ultrabithorax expression boundaries. Development. 1991 Dec;113(4):1171–1179. [PubMed] [Google Scholar]
  • Zink B, Paro R. In vivo binding pattern of a trans-regulator of homoeotic genes in Drosophila melanogaster. Nature. 1989 Feb 2;337(6206):468–471. [PubMed] [Google Scholar]
  • Paro R, Zink B. The Polycomb gene is differentially regulated during oogenesis and embryogenesis of Drosophila melanogaster. Mech Dev. 1993 Jan;40(1-2):37–46. [PubMed] [Google Scholar]
  • Zink B, Engström Y, Gehring WJ, Paro R. Direct interaction of the Polycomb protein with Antennapedia regulatory sequences in polytene chromosomes of Drosophila melanogaster. EMBO J. 1991 Jan;10(1):153–162.[PMC free article] [PubMed] [Google Scholar]
MRC Laboratory of Molecular Biology, Cambridge, UK.
MRC Laboratory of Molecular Biology, Cambridge, UK.
Copyright notice
Abstract
Polycomb group (Pc-G) proteins act to keep homeotic genes stably and heritably silenced during Drosophila development. Here, it is shown that Polycomb (Pc), one of the Pc-G proteins, acts as a transcriptional silencer in Drosophila embryos if tethered to reporter genes by the DNA binding domain of GAL4 (i.e. as a GAL-Pc fusion protein). The results suggest that silencing by GAL-Pc requires the C-terminal portion of Pc, but not the chromodomain. If a pulse of Gal-Pc is provided, synthetic reporter genes are repressed, though only transiently. In contrast, reporter genes containing homeotic gene sequences remain stably and heritably silenced in a Pc-G gene-dependent fashion, even when GAL-Pc is no longer present. This implies that GAL-Pc recruits Pc-G proteins to DNA and suggests that maintenance of silencing requires the anchoring of Pc-G proteins to specific cis-regulatory sequences present in homeotic genes. The extent of DNA over which the Pc-G machinery acts is quite selective, as silencing established on one enhancer does not necessarily 'spread' to a juxtaposed synthetic enhancer.
Collaboration tool especially designed for Life Science professionals.Drag-and-drop any entity to your messages.