Connectin, a target of homeotic gene control in Drosophila

Development ◽  
1992 ◽  
Vol 116 (4) ◽  
pp. 1163-1174 ◽  
Author(s):  
A.P. Gould ◽  
R.A. White
Keyword(s):  
Binding Site ◽  
Regulatory Region ◽  
Protein Product ◽  
Homeotic Gene ◽  
Homeotic Genes ◽  
Cell Surface Molecule ◽  
In Vivo Binding ◽  
Mediate Cell ◽  
Cell Cell

The homeotic genes of Drosophila encode transcription factors that specify morphological differences between segments. To identify the genes that they control, we developed a chromatin immunopurification approach designed to isolate in vivo binding sites for the products of the homeotic gene Ultrabithorax. Here, we report the analysis of one immunopurified binding site. This 110 bp fragment maps within a regulatory region of a gene under homeotic control, connectin. A 4 kb DNA fragment, including the immunopurified binding site, is sufficient to reproduce the appropriate homeotic control within a subset of the full tissue distribution of connectin. Analysis of the role of the 110 bp binding site indicates that it mediates transcriptional controls by Ultrabithorax and other homeotic genes. This is the first report of a functional in vivo binding site isolated using the chromatin immunopurification method. We also show that the protein product of the connectin gene is predicted to be a cell-surface molecule containing leucine-rich repeats. The protein, connectin, can mediate cell-cell adhesion thus suggesting a direct link between homeotic gene function and processes of cell-cell recognition.

scholarly journals Alterations in the binding site of the cyclic AMP receptor protein at the Escherichia coli galactose operon regulatory region

1988 ◽  
Vol 253 (3) ◽  
pp. 809-818 ◽  
Author(s):  
K Gaston ◽  
B Chan ◽  
A Kolb ◽  
J Fox ◽  
S Busby
Keyword(s):  
Escherichia Coli ◽  
Cyclic Amp ◽  
Binding Site ◽  
Consensus Sequence ◽  
Regulatory Region ◽  
Receptor Protein ◽  
Binding Assays ◽  
Cyclic Amp Receptor Protein ◽  
Stimulation Of

Gene manipulation techniques have been used to alter the binding site for the cyclic AMP-cyclic AMP receptor protein complex (cAMP-CRP) at the regulatory region of the Escherichia coli galactose (gal) operon. The effects of these changes on CRP-dependent stimulation of expression from the galP1 promoter in vivo have been measured, and gel binding assays have been used to measure the affinity of cAMP-CRP for the modified sites. Firstly we have deleted progressively longer sequences from upstream of the gal CRP site in order to locate the functional limit of the site. A deletion to -49, removing the first base that corresponds to the consensus sequence for a CRP binding site, is sufficient to reduce CRP binding and block CRP-dependent stimulation of P1. Secondly, we used synthetic oligonucleotides to invert the asymmetric nucleotide sequence at the gal CRP binding site or to make the sequence symmetric. Inversion of the site has little effect on CRP binding, the architecture of open complexes at P1 revealed by DNAase I footprinting, or the stimulation of transcription from P1. Making the site symmetric increases the affinity for CRP by over 50-fold and leads to increased transcription from P1, whilst hardly altering the DNAase I footprint of open complexes. Our results confirm that the strength of binding of CRP depends on the nature of the site and show that it is this that principally accounts for differences in CRP-dependent stimulation of transcription.

scholarly journals Molecular analysis of the interaction of LCMV with its cellular receptor α-dystroglycan

2001 ◽  
Vol 155 (2) ◽  
pp. 301-310 ◽  
Author(s):  
Stefan Kunz ◽  
Noemí Sevilla ◽  
Dorian B. McGavern ◽  
Kevin P. Campbell ◽  
Michael B.A. Oldstone
Keyword(s):  
Binding Site ◽  
Binding Affinity ◽  
Receptor Binding ◽  
Divalent Cations ◽  
Terminal Region ◽  
Cellular Receptor ◽  
Globular Domain ◽  
Cell Surface Molecule ◽  
Laminin 1

α-Dystroglycan (DG) has been identified as the cellular receptor for lymphocytic choriomeningitis virus (LCMV) and Lassa fever virus (LFV). This subunit of DG is a highly versatile cell surface molecule that provides a molecular link between the extracellular matrix (ECM) and a β-DG transmembrane component, which interacts with the actin-based cytoskeleton. In addition, DG exhibits a complex pattern of interaction with a wide variety of ECM and cellular proteins. In the present study, we characterized the binding of LCMV to α-DG and addressed the role of α-DG–associated host-derived proteins in virus infection. We found that the COOH-terminal region of α-DG's first globular domain and the NH2-terminal region of the mucin-related structures of α-DG together form the binding site for LCMV. The virus–α-DG binding unlike ECM α-DG interactions was not dependent on divalent cations. Despite such differences in binding, LCMV and laminin-1 use, in part, an overlapping binding site on α-DG, and the ability of an LCMV isolate to compete with laminin-1 for receptor binding is determined by its binding affinity to α-DG. This competition of the virus with ECM molecules for receptor binding likely explains the recently found correlation between the affinity of LCMV binding to α-DG, tissue tropism, and pathological potential. LCMV strains and variants with high binding affinity to α-DG but not low affinity binders are able to infect CD11c+ dendritic cells, which express α-DG at their surface. Infection followed by dysfunction of these antigen-presenting cells contributes to immunosuppression and persistent viral infection in vivo.

The DNA-binding polycomb group protein pleiohomeotic mediates silencing of a Drosophila homeotic gene

Development ◽  
1999 ◽  
Vol 126 (17) ◽  
pp. 3905-3913 ◽  
Author(s):  
C. Fritsch ◽  
J.L. Brown ◽  
J.A. Kassis ◽  
J. Muller
Keyword(s):  
Dna Binding ◽  
Binding Sites ◽  
Point Mutations ◽  
Polycomb Group ◽  
Homeotic Gene ◽  
Homeotic Genes ◽  
Polycomb Group Protein ◽  
Cis Acting ◽  
Group Protein

Polycomb group (PcG) proteins repress homeotic genes in cells where these genes must remain inactive during development. This repression requires cis-acting silencers, also called PcG response elements. Currently, these silencers are ill-defined sequences and it is not known how PcG proteins associate with DNA. Here, we show that the Drosophila PcG protein Pleiohomeotic binds to specific sites in a silencer of the homeotic gene Ultrabithorax. In an Ultrabithorax reporter gene, point mutations in these Pleiohomeotic binding sites abolish PcG repression in vivo. Hence, DNA-bound Pleiohomeotic protein may function in the recruitment of other non-DNA-binding PcG proteins to homeotic gene silencers.

In vivo binding site of pemphigus vulgaris antibodies and their fate during acantholysis

1989 ◽  
Vol 20 (4) ◽  
pp. 578-582 ◽  
Author(s):  
Keiji Iwatsuki ◽  
Masahiro Takigawa ◽  
Shunsuke Imaizumi ◽  
Mizuho Yamada
Keyword(s):  
Binding Site ◽  
Pemphigus Vulgaris ◽  
In Vivo Binding

scholarly journals A System of Cytokines Encapsulated in ExtraCellular Vesicles

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Wendy Fitzgerald ◽  
Michael L. Freeman ◽  
Michael M. Lederman ◽  
Elena Vasilieva ◽  
Roberto Romero ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Ex Vivo ◽  
Biological Effects ◽  
Cell Communication ◽  
Health And Disease ◽  
Mediate Cell ◽  
Multicellular Organisms ◽  
Cell Cell

Abstract Cytokines are soluble factors that mediate cell–cell communications in multicellular organisms. Recently, another system of cell–cell communication was discovered, which is mediated by extracellular vesicles (EVs). Here, we demonstrate that these two systems are not strictly separated, as many cytokines in vitro, ex vivo, and in vivo are released in EV-encapsulated forms and are capable of eliciting biological effects upon contact with sensitive cells. Association with EVs is not necessarily a property of a particular cytokine but rather of a biological system and can be changed upon system activation. EV-encapsulated cytokines were not detected by standard cytokine assays. Deciphering the regulatory mechanisms of EV-encapsulation will lead to a better understanding of cell–cell communications in health and disease.

scholarly journals Trithorax and ASH1 Interact Directly and Associate with the Trithorax Group-Responsive bxd Region of theUltrabithorax Promoter

1999 ◽  
Vol 19 (9) ◽  
pp. 6441-6447 ◽  
Author(s):  
Tanya Rozovskaia ◽  
Sergei Tillib ◽  
Sheryl Smith ◽  
Yurii Sedkov ◽  
Orit Rozenblatt-Rosen ◽  
...  
Keyword(s):  
Protein Complexes ◽  
Regulatory Region ◽  
Polytene Chromosomes ◽  
Homeotic Gene ◽  
Trithorax Group ◽  
Activator Proteins ◽  
Trxg Protein ◽  
Close Proximity

ABSTRACT Trithorax (TRX) and ASH1 belong to the trithorax group (trxG) of transcriptional activator proteins, which maintains homeotic gene expression during Drosophila development. TRX and ASH1 are localized on chromosomes and share several homologous domains with other chromatin-associated proteins, including a highly conserved SET domain and PHD fingers. Based on genetic interactions betweentrx and ash1 and our previous observation that association of the TRX protein with polytene chromosomes isash1 dependent, we investigated the possibility of a physical linkage between the two proteins. We found that the endogenous TRX and ASH1 proteins coimmunoprecipitate from embryonic extracts and colocalize on salivary gland polytene chromosomes. Furthermore, we demonstrated that TRX and ASH1 bind in vivo to a relatively small (4 kb) bxd subregion of the homeotic geneUltrabithorax (Ubx), which contains severaltrx response elements. Analysis of the effects ofash1 mutations on the activity of this regulatory region indicates that it also contains ash1 response element(s). This suggests that ASH1 and TRX act on Ubx in relatively close proximity to each other. Finally, TRX and ASH1 appear to interact directly through their conserved SET domains, based on binding assays in vitro and in yeast and on coimmunoprecipitation assays with embryo extracts. Collectively, these results suggest that TRX and ASH1 are components that interact either within trxG protein complexes or between complexes that act in close proximity on regulatory DNA to maintain Ubx transcription.

scholarly journals Trithorax- and Polycomb-Group Response Elements within an Ultrabithorax Transcription Maintenance Unit Consist of Closely Situated but Separable Sequences

1999 ◽  
Vol 19 (7) ◽  
pp. 5189-5202 ◽  
Author(s):  
Sergei Tillib ◽  
Svetlana Petruk ◽  
Yurii Sedkov ◽  
Alexander Kuzin ◽  
Miki Fujioka ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Protein Complexes ◽  
Expression Patterns ◽  
Regulatory Region ◽  
Protein Product ◽  
Polycomb Group ◽  
Response Elements ◽  
Complex Element ◽  
Group Response

ABSTRACT In Drosophila, two classes of genes, thetrithorax group and the Polycomb group, are required in concert to maintain gene expression by regulating chromatin structure. We have identified Trithorax protein (TRX) binding elements within the bithorax complex and have found that within thebxd/pbx regulatory region these elements are functionally relevant for normal expression patterns in embryos and confer TRX binding in vivo. TRX was localized to three closely situated sites within a 3-kb chromatin maintenance unit with a modular structure. Results of an in vivo analysis showed that these DNA fragments (each ∼400 bp) contain both TRX- and Polycomb-group response elements (TREs and PREs) and that in the context of the endogenousUltrabithorax gene, all of these elements are essential for proper maintenance of expression in embryos. Dissection of one of these maintenance modules showed that TRX- and Polycomb-group responsiveness is conferred by neighboring but separable DNA sequences, suggesting that independent protein complexes are formed at their respective response elements. Furthermore, we have found that the activity of this TRE requires a sequence (∼90 bp) which maps to within several tens of base pairs from the closest neighboring PRE and that the PRE activity in one of the elements may require a binding site for PHO, the protein product of the Polycomb-group genepleiohomeotic. Our results show that long-range maintenance of Ultrabithorax expression requires a complex element composed of cooperating modules, each capable of interacting with both positive and negative chromatin regulators.

scholarly journals Mechanisms of in vivo binding site selection of the hematopoietic master transcription factor PU.1

2013 ◽  
Vol 41 (13) ◽  
pp. 6391-6402 ◽  
Author(s):  
Thu-Hang Pham ◽  
Julia Minderjahn ◽  
Christian Schmidl ◽  
Helen Hoffmeister ◽  
Sandra Schmidhofer ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Binding Site ◽  
Site Selection ◽  
In Vivo Binding ◽  
Selection Of

Dissecting the temporal requirements for homeotic gene function

Development ◽  
1994 ◽  
Vol 120 (7) ◽  
pp. 1983-1995 ◽  
Author(s):  
J. Castelli-Gair ◽  
S. Greig ◽  
G. Micklem ◽  
M. Akam
Keyword(s):  
Gene Expression ◽  
Nervous System ◽  
Gene Function ◽  
Cell Types ◽  
Homeotic Gene ◽  
Homeotic Genes ◽  
Bithorax Complex ◽  
Cell Type ◽  
Homeotic Gene Expression

Homeotic genes confer identity to the different segments of Drosophila. These genes are expressed in many cell types over long periods of time. To determine when the homeotic genes are required for specific developmental events we have expressed the Ultrabithorax, abdominal-A and Abdominal-Bm proteins at different times during development using the GAL4 targeting technique. We find that early transient homeotic gene expression has no lasting effects on the differentiation of the larval epidermis, but it switches the fate of other cell types irreversibly (e.g. the spiracle primordia). We describe one cell type in the peripheral nervous system that makes sequential, independent responses to homeotic gene expression. We also provide evidence that supports the hypothesis of in vivo competition between the bithorax complex proteins for the regulation of their down-stream targets.

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