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Matthew P. Scott - One of the best experts on this subject based on the ideXlab platform.
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The Drosophila kismet gene is related to chromatin-remodeling factors and is required for both segmentation and segment identity.
Development (Cambridge England), 1999Co-Authors: Gary Daubresse, Matthew P. Scott, J A Kennison, Renate Deuring, L. Moore, Ophelia Papoulas, I. Zakrajsek, W.r. Waldrip, J W TamkunAbstract:The Drosophila kismet gene was identified in a screen for dominant suppressors of Polycomb, a repressor of Homeotic Genes. Here we show that kismet mutations suppress the Polycomb mutant phenotype by blocking the ectopic transcription of Homeotic Genes. Loss of zygotic kismet function causes Homeotic transformations similar to those associated with loss-of-function mutations in the Homeotic Genes Sex combs reduced and Abdominal-B. kismet is also required for proper larval body segmentation. Loss of maternal kismet function causes segmentation defects similar to those caused by mutations in the pair-rule gene even-skipped. The kismet gene encodes several large nuclear proteins that are ubiquitously expressed along the anterior-posterior axis. The Kismet proteins contain a domain conserved in the trithorax group protein Brahma and related chromatin-remodeling factors, providing further evidence that alterations in chromatin structure are required to maintain the spatially restricted patterns of Homeotic gene transcription.
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Setting limits on Homeotic gene function : restraint of Sex combs reduced activity by teashirt and other Homeotic Genes
The EMBO journal, 1994Co-Authors: Deborah J. Andrew, Michael A. Horner, Matthew Petitt, Sarah M. Smolik, Matthew P. ScottAbstract:Each of the Homeotic Genes of the HOM or HOX complexes is expressed in a limited domain along the anterior-posterior axis. Each Homeotic protein directs the formation of characteristic structures, such as wings or ribs. In flies, when a heat shock-inducible Homeotic gene is used to produce a Homeotic protein in all cells of the embryo, only some cells respond by altering their fates. We have identified Genes that limit where the Homeotic gene Sex combs reduced (Scr) can affect cell fates in the Drosophila embryo. In the abdominal cuticle Scr is prevented from inducing prothoracic structures by the three bithorax complex (BX-C) Homeotic Genes. However, two of the BX-C Homeotic Genes, Ultrabithorax (Ubx) and abdominal-A (abd-A), have no effect on the ability of Scr to direct the formation of salivary glands. Instead, salivary gland induction by Scr is limited in the trunk by the Homeotic gene teashirt (tsh) and in the last abdominal segment by the third BX-C gene, Abdominal-B (AbdB). Therefore, spatial restrictions on Homeotic gene activity differ between tissues and result both from the regulation of Homeotic gene transcription and from restraints on where Homeotic proteins can function.
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midgut morphoGenesis: secreted proteins mediate the action of Homeotic Genes
1994Co-Authors: Laura D. Mathies, Stephen Kerridge, Matthew P. ScottAbstract:Drosophila Homeotic Genes are present in two clusters, the Antennapedia complex (ANTC) and the Bithorax complex (BX-C). The two clusters are thought to have arisen from a split in a single ancestral complex, and are collectively termed the Homeotic complex, HOM-C. HOM-C Genes all encode transcription regulators containing a DNA-binding homeodomain. The fly Homeotic Genes are expressed in restricted domains along the anteriorposterior axis where they are able to organize cells to form segment-specific structures(Duncan, 1987; Mahaffey and Kaufman, 1988). Related HOM-C gene clusters have been identified in organisms as diverse as humans and the nematode C. elegansand are presumably present in all animals (McGinnis and Krumlauf, 1992). In mice and humans there are four clusters of Homeotic Genes, called Hox Genes, each of which appears to be related in spatial expression, protein sequence, and function with the HOM-C fly Genes. To some extent the Genes are functionally interchangeable between species; three Hox Genes act like their fly homologs in ectopic expression experiments in flies (Malicki et al., 1990; McGinnis et al., 1990; Zhao et al., 1993). Homeotic Genes are responsible for regional specification of cell fates in all organisms where their functions have been studied. Homeotic proteins regulate sets of target Genes, thus causing cells to follow developmental paths appropriate to their position in the animal. How are target Genes regulated by the Homeotic transcription factors? Do the proteins regulate similar sets of target Genes differently, or are the targets of each protein different? To what extent are the effects of Homeotic proteins tissue-specific or stage-specific? Are the effects of Homeotic proteins upon their targets cell autonomous or are cells influenced at a distance? The answers to these questions are central to understanding the roles Homeotic proteins play in pattern formation. Only a few target Genes have been identified to date (Andrew and Scott, 1992; Botas, 1993) and more must be found to learn how they work together in development. The relative simplicity of Drosophilamidgut morphology
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Role of the teashirt gene in Drosophila midgut morphoGenesis: secreted proteins mediate the action of Homeotic Genes
Development (Cambridge England), 1994Co-Authors: Laura D. Mathies, Stephen Kerridge, Matthew P. ScottAbstract:Homeotic Genes control the development of embryonic structure by coordinating the activities of downstream 'target' Genes. The identities and functions of target Genes must be understood in order to learn how Homeotic Genes control morphoGenesis. Drosophila midgut development is regulated by Homeotic Genes expressed in the visceral mesoderm, where two of their target Genes have been identified. Both encode secreted proteins. The Ultrabithorax (Ubx) Homeotic gene activates transcription of the decapentaplegic (dpp) gene, which encodes a TGF beta class protein, while in adjacent mesoderm cells the abdominal-A (abd-A) Homeotic gene activates transcription of the wingless (wg) gene, which encodes a Wnt class protein. The Homeotic Genes Antennapedia (Antp) and Sex combs reduced (Scr) act in more anterior midgut regions. Here we report the identification of another Homeotic gene target in the midgut mesoderm, the teashirt (tsh) gene, which encodes a protein with zinc finger motifs. tsh is necessary for proper formation of anterior and central midgut structures. Antp activates tsh in anterior midgut mesoderm. In the central midgut mesoderm Ubx, abd-A, dpp, and wg are required for proper tsh expression. The control of tsh by Ubx and abd-A, and probably also by Antp, is mediated by secreted signaling molecules. By responding to signals as well as localized transcription regulators, the tsh transcription factor is produced in a spatial pattern distinct from any of the Homeotic Genes.
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ectopic expression and function of the antp and scr Homeotic Genes the n terminus of the homeodomain is critical to functional specificity
Development, 1993Co-Authors: Wenlin Zeng, Deborah J. Andrew, Laura D. Mathies, Michael A. Horner, Matthew P. ScottAbstract:The transcription factors encoded by Homeotic Genes determine cell fates during development. Each Homeotic protein causes cells to follow a distinct pathway, presumably by differentially regulating downstream 'target' Genes. The homeodomain, the DNA-binding part of Homeotic proteins, is necessary for conferring the specificity of each Homeotic protein's action. The two Drosophila Homeotic proteins encoded by Antennapedia and Sex combs reduced determine cell fates in the epidermis and internal tissues of the posterior head and thorax. Genes encoding chimeric Antp/Scr proteins were introduced into flies and their effects on morphology and target gene regulation observed. We find that the N terminus of the homeodomain is critical for determining the specific effects of these Homeotic proteins in vivo, but other parts of the proteins have some influence as well. The N-terminal part of the homeodomain has been observed, in crystal structures and in NMR studies in solution, to contact the minor groove of the DNA. The different effects of Antennapedia and Sex combs reduced proteins in vivo may depend on differences in DNA binding, protein-protein interactions, or both.
Elliot M. Meyerowitz - One of the best experts on this subject based on the ideXlab platform.
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Floral Homeotic Genes are targets of gibberellin signaling in flower development
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: Hao Yu, Yuanxiang Zhao, Jinrong Peng, Prakash P. Kumar, Elliot M. MeyerowitzAbstract:Gibberellins (GAs) are a class of plant hormones involved in the regulation of flower development in Arabidopsis. The GA-deficient ga1-3 mutant shows retarded growth of all floral organs, especially abortive stamen development that results in complete male ste- rility. Until now, it has not been clear how GA regulates the late-stage development of floral organs after the establishment of their identities within floral meristems. Various combinations of null mutations of DELLA proteins can gradually rescue floral defects in ga1-3. In particular, the synergistic effect of rga-t2 and rgl2-1 can substantially restore flower development in ga1-3 .W e find that the transcript levels of floral Homeotic Genes APETALA3 (AP3), PISTILLATA (PI), and AGAMOUS (AG) are immediately up- regulated in young flowers of ga1-3 upon GA treatment. Using a steroid-inducible activation of RGA, we further demonstrated that these floral Homeotic Genes are transcriptionally repressed by RGA activity in young flowers whereas the expression of LEAFY (LFY) and APETALA1 (AP1) is not substantially affected. In addition, we observed the partial rescue of floral defects in ga1-3 by overex- pression of AG. Our results indicate that GA promotes the expres- sion of floral Homeotic Genes by antagonizing the effects of DELLA proteins, thereby allowing continued flower development.
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Floral Homeotic Genes are targets of gibberellin signaling in flower development
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: Toshiro Ito, Yuanxiang Zhao, Jinrong Peng, Prakash P. Kumar, Elliot M. MeyerowitzAbstract:Gibberellins (GAs) are a class of plant hormones involved in the regulation of flower development in Arabidopsis. The GA-deficient ga1-3 mutant shows retarded growth of all floral organs, especially abortive stamen development that results in complete male ste- rility. Until now, it has not been clear how GA regulates the late-stage development of floral organs after the establishment of their identities within floral meristems. Various combinations of null mutations of DELLA proteins can gradually rescue floral defects in ga1-3. In particular, the synergistic effect of rga-t2 and rgl2-1 can substantially restore flower development in ga1-3 .W e find that the transcript levels of floral Homeotic Genes APETALA3 (AP3), PISTILLATA (PI), and AGAMOUS (AG) are immediately up- regulated in young flowers of ga1-3 upon GA treatment. Using a steroid-inducible activation of RGA, we further demonstrated that these floral Homeotic Genes are transcriptionally repressed by RGA activity in young flowers whereas the expression of LEAFY (LFY) and APETALA1 (AP1) is not substantially affected. In addition, we observed the partial rescue of floral defects in ga1-3 by overex- pression of AG. Our results indicate that GA promotes the expres- sion of floral Homeotic Genes by antagonizing the effects of DELLA proteins, thereby allowing continued flower development.
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a homolog of no apical meristem is an immediate target of the floral Homeotic Genes apetala3 pistillata
Cell, 1998Co-Authors: Robert Sablowski, Elliot M. MeyerowitzAbstract:To understand how Homeotic Genes affect morphoGenesis and differentiation, their target Genes must be identified. In Arabidopsis flowers, the Homeotic protein heterodimer APETALA3/PISTILLATA is necessary for petal and stamen formation. Here, AP3/PI function was put under posttranslational control to analyze its immediate effect on the floral mRNA population, with indirect effects blocked by cycloheximide. Using differential display, a target gene of AP3/PI was identified (NAP: NAC-LIKE, ACTIVATED BY AP3/PI), which is homologous to Genes required for meristem establishment and separation of floral organs. The expression pattern of NAP and the phenotypes caused by its misexpression suggest that it functions in the transition between growth by cell division and cell expansion in stamens and petals.
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The search for flower Homeotic gene homologs in basal angiosperms and gnetales: a potential new source of data on the evolutionary origin of flowers
International Journal of Plant Sciences, 1997Co-Authors: Michael W. Frohlich, Elliot M. MeyerowitzAbstract:The evolutionary origin of flowering plants has long been contentious. The large morphological gap between flowering plants and their potential gymnosperm relatives makes homology difficult to assess. Uncertainty at the base of the angiosperm clade prevents firm reconstruction of plesiomorphic flower characters. The recent discovery of Homeotic Genes that specify flowers and flower organs raises the possibility of a new class of evidence bearing on flower origins. Homeotic Genes may give strong evidence on homology. Sequence changes or events related to morphological evolution may help resolve the base of the flowering plant tree. This article reports the creation of resources to facilitate isolation of Homeotic and other Genes from taxa critical to flowering plant origins: we have made 16 genomic DNA libraries of 15 species, including Gnetales (Welwitschia [two libraries], Gnetum [two species], and Ephedra) and basal angiosperms (Nymphaea, Peperomia, Magnolia, Illicium, Drimys, Cinnamomum, Trochodendron,...
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the abcs of floral Homeotic Genes
Cell, 1994Co-Authors: Detlef Weigel, Elliot M. MeyerowitzAbstract:Homeotic mutants, that is, mutants with a normal organ in a place where an organ of another type is typically found, were first recognized in plants. The earliest descriptions of mutants in which petals replace stamens, giving double flowers, go back to ancient Greece and Rome. Similar accounts can be found in the botanical literature of China more than a thousand years ago, and in the books of the herbalists of Renaissance Europe (Meyerowitz et al., 1989). The use of such mutants (and similar but noninherited developmental abnormalities) to understand developmental processes in plants is more recent, dating from Linnaeus in the mid-eighteenth century (see Cullen and Stevens, 1990), and from Goethe (1790), who derived the ideas of organ homology and homological comparison from plants showing what was then called abnormal metamorphosis. Our term homeosis dates from Bateson’s work (1894) on organismal variation, in which he expanded Masters’treatment (1889) of abnormal metamorphosis in plants to animals and introduced the term homoeosis as a replacement for the older term. Goethe (1790) used Homeotic variation in plants as the basis for a specific model explaining the developmental origin of different organ types in flowers. In his view, the four types of floral organs (sepals, petals, stamens, and carpels) are all modified leaves. As sap rises through developing flowers it is progressively refined, thereby inducing different organ types in different positions.
Gunter Theissen - One of the best experts on this subject based on the ideXlab platform.
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characterization of candidate class a b and e floral Homeotic Genes from the perianthless basal angiosperm chloranthus spicatus chloranthaceae
Development Genes and Evolution, 2005Co-Authors: Zheng Meng, Hongzhi Kong, Zhiduan Chen, Gunter TheissenAbstract:The classic ABC model explains the activities of each class of floral Homeotic Genes in specifying the identity of floral organs. Thus, changes in these Genes may underlay the origin of floral diversity during evolution. In this study, three MADS-box Genes were isolated from the perianthless basal angiosperm Chloranthus spicatus. Sequence and phylogenetic analyses revealed that they are AP1-like, AP3-like and SEP3-like Genes, and hence these Genes were termed CsAP1, CsAP3 and CsSEP3, respectively. Due to these assignments, they represent candidate class A, class B and class E Genes, respectively. Expression patterns suggest that the CsAP1, CsAP3 and CsSEP3 Genes function during flower development of C. spicatus. CsAP1 is expressed broadly in the flower, which may reflect the ancestral function of SQUA-like Genes in the specification of inflorescence and floral meristems rather than in patterning of the flower. CsAP3 is exclusively expressed in male floral organs, providing the evidence that AP3-like Genes have ancestral function in differentiation between male and female reproductive organs. CsSEP3 expression is not detectable in spike meristems, but its mRNA accumulates throughout the flower, supporting the view that SEP-like Genes have conserved expression pattern and function throughout angiosperm. Studies of synonymous vs nonsynonymous nucleotide substitutions indicate that these Genes have not evolved under changes in evolutionary forces. All the data above suggest that the Genes may have maintained at least some ancestral functions despite the lack of perianth in the flowers of C. spicatus.
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heterotopic expression of class b floral Homeotic Genes supports a modified abc model for tulip tulipa gesneriana
Plant Molecular Biology, 2003Co-Authors: Heinz Saedler, Akira Kanno, Hiroshi Saeki, Toshiaki Kameya, Gunter TheissenAbstract:In higher eudicotyledonous angiosperms the floral organs are typically arranged in four different whorls, containing sepals, petals, stamens and carpels. According to the ABC model, the identity of these organs is specified by floral Homeotic Genes of class A, A+B, B+C and C, respectively. In contrast to the sepal and petal whorls of eudicots, the perianths of many plants from the Liliaceae family have two outer whorls of almost identical petaloid organs, called tepals. To explain the Liliaceae flower morphology, van Tunen et al. (1993) proposed a modified ABC model, exemplified with tulip. According to this model, class B Genes are not only expressed in whorls 2 and 3, but also in whorl 1. Thus the organs of both whorls 1 and 2 express class A plus class B Genes and, therefore, get the same petaloid identity. To test this modified ABC model we have cloned and characterized putative class B Genes from tulip. Two DEF- and one GLO-like gene were identified, named TGDEFA, TGDEFB and TGGLO. Northern hybridization analysis showed that all of these Genes are expressed in whorls 1, 2 and 3 (outer and inner tepals and stamens), thus corroborating the modified ABC model. In addition, these experiments demonstrated that TGGLO is also weakly expressed in carpels, leaves, stems and bracts. Gel retardation assays revealed that TGGLO alone binds to DNA as a homodimer. In contrast, TGDEFA and TGDEFB cannot homodimerize, but make heterodimers with PI. Homodimerization of GLO-like protein has also been reported for lily, suggesting that this phenomenon is conserved within Liliaceae plants or even monocot species.
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on the origin of class b floral Homeotic Genes functional substitution and dominant inhibition in arabidopsis by expression of an orthologue from the gymnosperm gnetum
Plant Journal, 2002Co-Authors: Kaiuwe Winter, Heinz Saedler, Gunter TheissenAbstract:Class B floral Homeotic Genes are involved in specifying stamen and petal identity in angiosperms (flowering plants). Here we report that gymnosperms, the closest relatives of the angiosperms, contain at least two different clades representing putative orthologues of class B Genes, termed GGM2-like and DAL12-like Genes. To obtain information about the functional conservation of the class B Genes in seed plants, the representative of one of these clades from Gnetum, termed GGM2, was expressed under the control of the CaMV 35S promoter in Arabidopsis wild-type plants and in different class B mutants. In wild-type plants and in a conditional mutant grown at a permissive temperature, gain-of-function phenotypes were obtained in whorls 1 and 4, where class B Genes are usually not expressed. In contrast, loss-of-function phenotypes were observed in whorls 2 and 3, where class B Genes are expressed. In different class B gene null mutants of Arabidopsis, and in the conditional B mutant grown at the non-permissive temperature, a partial complementation of the mutant phenotype was obtained. In situ hybridization studies and class B gene promoter test fusion experiments demonstrated that the gain-of-function phenotypes are not due to an upregulation of the endogenous B Genes from Arabidopsis, and hence probably involve interactions between GGM2 protein homodimers and class B protein target Genes other than the Arabidopsis class B Genes itself. To our knowledge, this is the first time that partial complementation of a Homeotic mutant by an orthologous gene from a distantly related species has been reported. These data suggest that GGM2 has a function in the gymnosperm Gnetum which is related to that of class B floral organ identity Genes of angiosperms. That function may be in the specification of male reproductive organ identity, and in distinguishing male from female reproductive organs.
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a novel mads box gene subfamily with a sister group relationship to class b floral Homeotic Genes
Molecular Genetics and Genomics, 2002Co-Authors: Annette Becker, Kerstin Kaufmann, Andreas Freialdenhoven, C Vincent, Heinz Saedler, M A Li, Gunter TheissenAbstract:Class B floral Homeotic Genes specify the identity of petals and stamens during the development of angiosperm flowers. Recently, putative orthologs of these Genes have been identified in different gymnosperms. Together, these Genes constitute a clade, termed B Genes. Here we report that diverse seed plants also contain members of a hitherto unknown sister clade of the B Genes, termed Bsister (Bs) Genes. We have isolated members of the Bs clade from the gymnosperm Gnetum gnemon, the monocotyledonous angiosperm Zea mays and the eudicots Arabidopsis thaliana and Antirrhinum majus. In addition, MADS-box Genes from the basal angiosperm Asarum europaeum and the eudicot Petunia hybrida were identified as Bs Genes. Comprehensive expression studies revealed that Bs Genes are mainly transcribed in female reproductive organs (ovules and carpel walls). This is in clear contrast to the B Genes, which are predominantly expressed in male reproductive organs (and in angiosperm petals). Our data suggest that the Bs Genes played an important role during the evolution of the reproductive structures in seed plants. The establishment of distinct B and Bs gene lineages after duplication of an ancestral gene may have accompanied the evolution of male microsporophylls and female megasporophylls 400–300 million years ago. During flower evolution, expression of Bs Genes diversified, but the focus of expression remained in female reproductive organs. Our findings imply that a clade of highly conserved close relatives of class B floral Homeotic Genes has been completely overlooked until recently and awaits further evaluation of its developmental and evolutionary importance. Electronic supplementary material to this paper can be obtained by using the Springer Link server located at http://dx.doi.org/10.1007/s00438-001-0615-8.
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a def glo like mads box gene from a gymnosperm pinus radiata contains an ortholog of angiosperm b class floral Homeotic Genes
Developmental Genetics, 1999Co-Authors: A Mouradov, Jan T. Kim, B Hamdorf, R D Teasdale, K U Winter, Gunter TheissenAbstract:The specification of floral organ identity during development depends on the function of a limited number of Homeotic Genes grouped into three classes: A, B, and C. Pairs of paralogous B class Genes, such as DEF and GLO in Antirrhinum, and AP3 and PI in Arabidopsis, are required for establishing petal and stamen identity. To gain a better understanding of the evolutionary origin of petals and stamens, we have looked for orthologs of B class Genes in conifers. Here we report cDNA cloning of PrDGL (Pinus radiata DEF/GLO-like gene) from radiata pine. We provide phylogenetic evidence that PrDGL is closely related to both DEF- and GLO-like Genes of angiosperms, and is thus among the first putative orthologs of floral Homeotic B function Genes ever reported from a gymnosperm. Expression of PrDGL is restricted to the pollen strobili (male cones) and was not detected in female cones. PrDGL expression was first detected in emergent male cone primordia and persisted through the early stages of pollen cone bud differentiation. Based on the results of our phylogeny reconstructions and expression studies, we suggest that PrDGL could play a role in distinguishing between male (where expression is on) and female reproductive structures (where expression is off) in radiata pine. We speculate that this could be the general function of DEF/GLO-like Genes in gymnosperms that may have been recruited for the distinction between stamens and carpels, the male and female reproductive organs of flowering plants, during the evolution of angiosperms out of gymnosperm-like ancestors.
J A Kennison - One of the best experts on this subject based on the ideXlab platform.
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The Drosophila kismet gene is related to chromatin-remodeling factors and is required for both segmentation and segment identity.
Development (Cambridge England), 1999Co-Authors: Gary Daubresse, Matthew P. Scott, J A Kennison, Renate Deuring, L. Moore, Ophelia Papoulas, I. Zakrajsek, W.r. Waldrip, J W TamkunAbstract:The Drosophila kismet gene was identified in a screen for dominant suppressors of Polycomb, a repressor of Homeotic Genes. Here we show that kismet mutations suppress the Polycomb mutant phenotype by blocking the ectopic transcription of Homeotic Genes. Loss of zygotic kismet function causes Homeotic transformations similar to those associated with loss-of-function mutations in the Homeotic Genes Sex combs reduced and Abdominal-B. kismet is also required for proper larval body segmentation. Loss of maternal kismet function causes segmentation defects similar to those caused by mutations in the pair-rule gene even-skipped. The kismet gene encodes several large nuclear proteins that are ubiquitously expressed along the anterior-posterior axis. The Kismet proteins contain a domain conserved in the trithorax group protein Brahma and related chromatin-remodeling factors, providing further evidence that alterations in chromatin structure are required to maintain the spatially restricted patterns of Homeotic gene transcription.
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Transcriptional activation of Drosphila Homeotic Genes form distant regulatory elements
Trends in genetics : TIG, 1993Co-Authors: J A KennisonAbstract:In Drosophila the Genes responsible for specifying segment identity (the Homeotic Genes) are transcribed in complex patterns during development. Mutations that mimic loss of Homeotic gene activity identify cis-acting DNA sequences and trans-acting proteins required for transcriptional activation. Some of the trans-acting proteins may facilitate interactions between cis-regulatory elements and the promoter by bringing together distant chromosomal elements.
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brahma a regulator of drosophila Homeotic Genes structurally related to the yeast transcriptional activator snf2swi2
Cell, 1992Co-Authors: Matthew P. Scott, J A Kennison, J W Tamkun, Renate Deuring, Mark Kissinger, Angela M Pattatucci, Thomas C KaufmanAbstract:The brahma (brm) gene is required for the activation of multiple Homeotic Genes in Drosophila. Loss-of-function brm mutations suppress mutations in Polycomb, a repressor of Homeotic Genes, and cause developmental defects similar to those arising from insufficient expression of the Homeotic Genes of the Antennapedia and Bithorax complexes. The brm gene encodes a 1638 residue protein that is similar to SNF2/SWI2, a protein involved in transcriptional activation in yeast, suggesting possible models for the role of brm in the transcriptional activation of Homeotic Genes. In addition, both brm and SNF2 contain a 77 amino acid motif that is found in other Drosophila, yeast, and human regulatory proteins and may be characteristic of a new family of regulatory proteins.
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Trans-regulation of Homeotic Genes in Drosophila.
The New biologist, 1992Co-Authors: J A Kennison, J W TamkunAbstract:Homeotic Genes of the Antennapedia and bithorax complexes control Drosophila development by encoding DNA-binding proteins that regulate the transcription of target Genes. Because either the presence or absence of these DNA-binding proteins alters development, regulation of the spatial patterns of expression is crucial to normal development. Numerous gene products are required for properly regulated expression of Antennapedia and bithorax complex Genes, but few (if any) are dedicated solely to the regulation of these Genes. One of the pleiotropic activators of Homeotic Genes in Drosophila, the brahma gene, encodes a protein similar to a yeast protein that is required for transcriptional activation of multiple tightly regulated Genes. Other components of this system may be conserved as well, suggesting that the biochemical basis for induced gene expression in single-celled organisms may have more in common with programmed developmental pathways in multicellular organisms than previously thought.
Koji Goto - One of the best experts on this subject based on the ideXlab platform.
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arabidopsis terminal flower 2 gene encodes a heterochromatin protein 1 homolog and represses both flowering locus t to regulate flowering time and several floral Homeotic Genes
Plant and Cell Physiology, 2003Co-Authors: Toshihisa Kotake, Shinobu Takada, Kenji Nakahigashi, Masaaki Ohto, Koji GotoAbstract:;Floral transition should be strictly regulated because it is one of the most critical developmental processes in plants. Arabidopsis terminal flower 2 (tfl2) mutants show an early-flowering phenotype that is relatively insensitive to photoperiod, as well as several other pleiotropic phenotypes. We found that the early flowering of tfl2 is caused mainly by ectopic expression of the FLOWERING LOCUS T (FT) gene, a floral pathway integrator. Molecular cloning of TFL2 showed that it encodes a protein with homology to heterochromatin protein 1 (HP1) of animals and Swi6 of fission yeast. TFL2 protein localizes in subnuclear foci and expression of the TFL2 gene complemented yeast swi6 – mutants. These results suggested that TFL2 might function as an HP1 in Arabidopsis. Gene expression analyses using DNA microarrays, however, did not show an increase in the expression of heterochromatin Genes in tfl2 mutants but instead showed the upregulation of the floral Homeotic Genes APETALA3, PISTILLATA, AGAMOUS and SEPALLATA3. The pleiotropic phenotype of the tfl2 mutant could reflect the fact that TFL2 represses the expression of multiple Genes. Our results demonstrate that despite its homology to HP1, TFL2 is involved in the repression of specific euchromatin Genes and not heterochromatin Genes in Arabidopsis.
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arabidopsis terminal flower 2 gene encodes a heterochromatin protein 1 homolog and represses both flowering locus t to regulate flowering time and several floral Homeotic Genes
Plant and Cell Physiology, 2003Co-Authors: Toshihisa Kotake, Shinobu Takada, Kenji Nakahigashi, Masaaki Ohto, Koji GotoAbstract:Floral transition should be strictly regulated because it is one of the most critical developmental processes in plants. Arabidopsis terminal flower 2 (tfl2) mutants show an early-flowering phenotype that is relatively insensitive to photoperiod, as well as several other pleiotropic phenotypes. We found that the early flowering of tfl2 is caused mainly by ectopic expression of the FLOWERING LOCUS T (FT) gene, a floral pathway integrator. Molecular cloning of TFL2 showed that it encodes a protein with homology to heterochromatin protein 1 (HP1) of animals and Swi6 of fission yeast. TFL2 protein localizes in subnuclear foci and expression of the TFL2 gene complemented yeast swi6(-) mutants. These results suggested that TFL2 might function as an HP1 in Arabidopsis: Gene expression analyses using DNA microarrays, however, did not show an increase in the expression of heterochromatin Genes in tfl2 mutants but instead showed the upregulation of the floral Homeotic Genes APETALA3, PISTILLATA, AGAMOUS and SEPALLATA3. The pleiotropic phenotype of the tfl2 mutant could reflect the fact that TFL2 represses the expression of multiple Genes. Our results demonstrate that despite its homology to HP1, TFL2 is involved in the repression of specific euchromatin Genes and not heterochromatin Genes in Arabidopsis.