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Corey Largman - One of the best experts on this subject based on the ideXlab platform.
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activation of stem cell specific genes by hoxa9 and hoxa10 Homeodomain Proteins in cd34 human cord blood cells
Stem Cells, 2005Co-Authors: Christina M Ferrell, Corey Largman, Sheri T Dorsam, Hideaki Ohta, Keith R Humphries, Mika K Derynck, Christopher M Haqq, Jeffrey H LawrenceAbstract:There is growing evidence for a role of HOX Homeodomain Proteins in normal hematopoiesis. Several HOX genes, including HOXA9 and HOXA10, are expressed in primitive hematopoietic cells, implying a role in early hematopoietic differentiation. To identify potential target genes of these two closely related transcription factors, human CD34+ umbilical cord blood cells were transduced with vectors expressing either HOXA9 or HOXA10 and analyzed with cDNA micro-arrays. Statistical analysis using significance analysis of microarrays revealed a common signature of several hundred genes, demonstrating that the transcriptomes of HOXA9 and HOXA10 largely overlap in this cellular context. Seven genes that were upregulated by both HOX Proteins were validated by real-time reverse transcription polymerase chain reaction. HOXA9 and HOXA10 showed positive regulation of genes in the Wnt pathway, including Wnt10B and two Wnt receptors Frizzled 1 and Frizzled 5, an important pathway for hematopoietic stem cell (HSC) self-renewal. Other validated genes included v-ets-related gene (ERG), Iroquois 3 (IRX3), aldehyde dehydrogenase 1 (ALDH1), and very long–chain acyl-CoA synthetase homolog 1 (VLCS-H1). GenMAPP (Gene Micro Array Pathway Profiler) analysis indicated that HOXA10 repressed expression of several genes involved in heme biosynthesis and three globin genes, indicating a general suppression of erythroid differentiation. A number of genes regulated by HOXA9 and HOXA10 are expressed in normal HSC populations.
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Analysis of HOX Homeodomain Proteins and gene transcripts in the epidermis.
Methods in molecular biology (Clifton N.J.), 2005Co-Authors: László G. Kömüves, Corey LargmanAbstract:HOX Homeodomain Proteins are thought to be master developmental regulators of tissue patterning during embryogenesis. These DNA binding Proteins also have diverse roles in adult cell function, and derangement of HOX genes has been associated with several types of cancer. In this chapter we present protocols for the immunohistochemical localization of HOX Proteins in the epidermis. We also provide in situ hybridization protocols for detection of HOX gene mRNA transcripts in the epidermis.
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the hox Homeodomain Proteins block cbp histone acetyltransferase activity
Molecular and Cellular Biology, 2001Co-Authors: Wei-fang Shen, H J Lawrence, Keerthi Krishnan, Corey LargmanAbstract:Despite the identification of PBC Proteins as cofactors that provide DNA affinity and binding specificity for the HOX Homeodomain Proteins, HOX Proteins do not demonstrate robust activity in transient-transcription assays and few authentic downstream targets have been identified for these putative transcription factors. During a search for additional cofactors, we established that each of the 14 HOX Proteins tested, from 11 separate paralog groups, binds to CBP or p300. All six isolated Homeodomain fragments tested bind to CBP, suggesting that the Homeodomain is a common site of interaction. Surprisingly, CBP-p300 does not form DNA binding complexes with the HOX Proteins but instead prevents their binding to DNA. The HOX Proteins are not substrates for CBP histone acetyltransferase (HAT) but instead inhibit the activity of CBP in both in vitro and in vivo systems. These mutually inhibitory interactions are reflected by the inability of CBP to potentiate the low levels of gene activation induced by HOX Proteins in a range of reporter assays. We propose two models for HOX protein function: (i) HOX Proteins may function without CBP HAT to regulate transcription as cooperative DNA binding molecules with PBX, MEIS, or other cofactors, and (ii) the HOX Proteins may inhibit CBP HAT activity and thus function as repressors of gene transcription.
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ABDB-LIKE HOX Proteins STABILIZE DNA BINDING BY THE MEIS1 Homeodomain Proteins
Molecular and cellular biology, 1997Co-Authors: Wei-fang Shen, J C Montgomery, S Rozenfeld, J J Moskow, H J Lawrence, A. M. Buchberg, Corey LargmanAbstract:Recent studies show that Hox Homeodomain Proteins from paralog groups 1 to 10 gain DNA binding specificity and affinity through cooperative binding with the divergent Homeodomain protein Pbx1. However, the AbdB-like Hox Proteins from paralogs 11, 12, and 13 do not interact with Pbx1a, raising the possibility of different protein partners. The Meis1 homeobox gene has 44% identity to Pbx within the Homeodomain and was identified as a common site of viral integration in myeloid leukemias arising in BXH-2 mice. These integrations result in constitutive activation of Meis1. Furthermore, the Hoxa-9 gene is frequently activated by viral integration in the same BXH-2 leukemias, suggesting a biological synergy between these two distinct classes of Homeodomain Proteins in causing malignant transformation. We now show that the Hoxa-9 protein physically interacts with Meis1 Proteins by forming heterodimeric binding complexes on a DNA target containing a Meis1 site (TGACAG) and an AbdB-like Hox site (TTTTACGAC). Hox Proteins from the other AbdB-like paralogs, Hoxa-10, Hoxa-11, Hoxd-12, and Hoxb-13, also form DNA binding complexes with Meis1b, while Hox Proteins from other paralogs do not appear to interact with Meis1 Proteins. DNA binding complexes formed by Meis1 with Hox Proteins dissociate much more slowly than DNA complexes with Meis1 alone, suggesting that Hox Proteins stabilize the interactions of Meis1 Proteins with their DNA targets.
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the abd b like hox Homeodomain Proteins can be subdivided by the ability to form complexes with pbx1a on a novel dna target
Journal of Biological Chemistry, 1997Co-Authors: Wei-fang Shen, S Rozenfeld, H J Lawrence, Corey LargmanAbstract:Abstract Previous studies showed that the Hox Homeodomain Proteins from paralog groups 1–8 display cooperative DNA binding with the non-Hox Homeodomain protein Pbx, mediated by a canonical YPWM. Although the Abd-B-like Hox Proteins in paralogs 9–13 lack this sequence, Hoxb-9 and Hoxa-10 were reported to bind with Pbx1a to DNA. We show that these interactions require a tryptophan 6 amino acids N-terminal to the Homeodomain. Binding site selection for Hoxb-9 with Pbx1a yielded ATGATGAC, containing a novel TTAC Hox-binding site adjacent to a Pbx site. In the presence of Pbx1a, Hoxb-9 and Hoxa-10 bound to targets containing either TTAC or TTAT. These data extend previous findings that interactions with Pbx define a Hox protein binding code for different DNA sequences across paralog groups 1 through 10. Members of the 11, 12, and 13 paralogs do not cooperatively bind DNA with Pbx1a, despite the presence of tryptophan residues N-terminal to the Homeodomain in Hoxd-12 and Hoxd-13. Hoxa-11, Hoxd-12, or Hoxd-13, in the presence of Pbx1a, selected a TTAC Hox site but lacking a Pbx1a site. These data suggest that Abd-B-like Hox Proteins bind to a novel TTAC site and can be divided by their cooperative binding to DNA with Pbx1a.
Jörg Kämper - One of the best experts on this subject based on the ideXlab platform.
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Regulation of pathogenic development in the corn smut fungus Ustilago maydis.
Molecular plant pathology, 2000Co-Authors: Annemarie Grandel, Tina Romeis, Jörg KämperAbstract:Abstract In Ustilago maydis, the b mating type locus constitutes the central regulatory domain for pathogenic development. The b locus encodes two Homeodomain Proteins that are thought to function as transcriptional regulators. Here we describe our current view of the different regulatory pathways in which the b locus is involved. We emphasize on the development of tools for the isolation of genes that are directly regulated by b Homeodomain Proteins.
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multiallelic recognition nonself dependent dimerization of the be and bw Homeodomain Proteins in ustilago maydis
Cell, 1995Co-Authors: Jörg Kämper, Tina Romeis, Michael Reichmann, Michael Bolker, Regine KahmannAbstract:In the plant pathogenic fungus Ustilago maydis, sexual and pathogenic development are controlled by the multiallelic b mating-type locus. The b locus encodes a pair of unrelated Homeodomain Proteins termed bE and bW, with allelic differences clustering in the N-terminal domains of both polypeptides. Only combinations of bE and bW of different allelic origin are active. We have investigated the underlying molecular mechanism for this intracellular self/nonself recognition phenomenon. By using the two-hybrid system, we were able to show that bE and bW dimerize only if they are derived from different alleles. Dimerization involves the N-terminal variable domains. Different point mutants of bE2 were isolated that function in combination with bW2. The majority of such bE2 mutant polypeptides were also able to form heterodimers with bW2 in the two-hybrid system. Nonself-dependent dimerization of bE and bW was supported with a biochemical interaction assay with immobilized Proteins. Our results suggest a model for self/nonself recognition in which variable cohesive contacts direct dimerization.
Pamela L Mellon - One of the best experts on this subject based on the ideXlab platform.
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the groucho related gene family regulates the gonadotropin releasing hormone gene through interaction with the Homeodomain Proteins msx1 and oct1
Journal of Biological Chemistry, 2005Co-Authors: Naama Raveharel, Marjory L Givens, Nichol L G Miller, Pamela L MellonAbstract:Gonadotropin-releasing hormone (GnRH) is exclusively expressed in a unique population of hypothalamic neurons that controls reproductive function. GnRH gene expression is highly dynamic. Its transcriptional activity is regulated in a complex spatiotemporal manner during embryonic development and postnatal life. Although a variety of transcription factors have been identified as regulators of GnRH transcription, most are promiscuous in their DNA-binding requirements, and none are solely expressed in GnRH neurons. Their specific activity is probably determined by interactions with distinct cofactors. Here we find that the Groucho-related gene (GRG) family of co-repressors is expressed in a model cell line for the GnRH neuron and co-expresses with GnRH during prenatal development. GRG Proteins associate in vivo with the GnRH promoter. Furthermore, GRG Proteins interact with two regulators of GnRH transcription, the Homeodomain Proteins MSX1 and OCT1. Co-transfection experiments indicate that GRG Proteins regulate GnRH promoter activity. The long GRG forms enhance MSX1 repression and counteract OCT1 activation of the GnRH gene. In contrast, the short form, GRG5, has a dominant-negative effect on MSX1-dependent repression. Taken together, these data suggest that the dynamic switch between activation and repression of GnRH transcription is mediated by recruitment of the GRG co-regulators.
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tale Homeodomain Proteins regulate gonadotropin releasing hormone gene expression independently and via interactions with oct 1
Journal of Biological Chemistry, 2004Co-Authors: Naama Raveharel, Mark P. Kamps, Marjory L Givens, Shelley B Nelson, Hao A Duong, Djurdjica Coss, Melody E Clark, Sara B Hall, Pamela L MellonAbstract:Gonadotropin-releasing hormone (GnRH) is the central regulator of reproductive function. Expression of the GnRH gene is confined to a rare population of neurons scattered throughout the hypothalamus. Restricted expression of the rat GnRH gene is driven by a multicomponent enhancer and an evolutionarily conserved promoter. Oct-1, a ubiquitous POU Homeodomain transcription factor, was identified as an essential factor regulating GnRH transcription in the GT1-7 hypothalamic neuronal cell line. In this study, we conducted a two-hybrid interaction screen in yeast using a GT1-7 cDNA library to search for specific Oct-1 cofactors. Using this approach, we isolated Pbx1b, a TALE Homeodomain transcription factor that specifically associates with Oct-1. We show that heterodimers containing Pbx/Prep1 or Pbx/Meis1 TALE Homeodomain Proteins bind to four functional elements within the GnRH regulatory region, each in close proximity to an Oct-1-binding site. Cotransfection experiments indicate that TALE Proteins are essential for GnRH promoter activity in the GT1-7 cells. Moreover, Pbx1 and Oct-1, as well as Prep1 and Oct-1, form functional complexes that enhance GnRH gene expression. Finally, Pbx1 is expressed in GnRH neurons in embryonic as well as mature mice, suggesting that the associations between TALE Homeodomain Proteins and Oct-1 regulate neuron-specific expression of the GnRH gene in vivo.
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activin regulation of the follicle stimulating hormone β subunit gene involves smads and the tale Homeodomain Proteins pbx1 and prep1
Molecular Endocrinology, 2004Co-Authors: Janice S Bailey, Naama Raveharel, Djurdjica Coss, Shauna M Mcgillivray, Pamela L MellonAbstract:FSH is critical for normal reproductive function in both males and females. Activin, a member of the TGFβ family of growth factors, is an important regulator of FSH expression, but little is known about the molecular mechanisms through which it acts. We used transient transfections into the immortalized gonadotrope cell line LβT2 to identify three regions (at −973/−962, −167, and −134) of the ovine FSH β-subunit gene that are required for full activin response. All three regions contain homology to consensus binding sites for Smad Proteins, the intracellular mediators of TGFβ family signaling. Mutation of the distal site reduces activin responsiveness, whereas mutation of either proximal site profoundly disrupts activin regulation of the FSHβ gene. These sites specifically bind LβT2 nuclear Proteins in EMSAs, and the −973/−962 site binds Smad4 protein. Interestingly, the protein complex binding to the −134 site contains Smad4 in association with the Homeodomain Proteins Pbx1 and Prep1. Using glutathione S...
Jacqueline M Matthews - One of the best experts on this subject based on the ideXlab platform.
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Structural Basis for Partial Redundancy in a Class of Transcription Factors, the LIM Homeodomain Proteins, in Neural Cell Type Specification
The Journal of biological chemistry, 2011Co-Authors: M.s. Gadd, Mugdha Bhati, J. Mitchell Guss, Cy M. Jeffries, Jill Trewhella, David B. Langley, Jacqueline M MatthewsAbstract:Combinations of LIM Homeodomain Proteins form a transcriptional "LIM code" to direct the specification of neural cell types. Two paralogous pairs of LIM Homeodomain Proteins, LIM homeobox protein 3/4 (Lhx3/Lhx4) and Islet-1/2 (Isl1/Isl2), are expressed in developing ventral motor neurons. Lhx3 and Isl1 interact within a well characterized transcriptional complex that triggers motor neuron development, but it was not known whether Lhx4 and Isl2 could participate in equivalent complexes. We have identified an Lhx3-binding domain (LBD) in Isl2 based on sequence homology with the Isl1(LBD) and show that both Isl2(LBD) and Isl1(LBD) can bind each of Lhx3 and Lhx4. X-ray crystal- and small-angle x-ray scattering-derived solution structures of an Lhx4·Isl2 complex exhibit many similarities with that of Lhx3·Isl1; however, structural differences supported by mutagenic studies reveal differences in the mechanisms of binding. Differences in binding have implications for the mode of exchange of protein partners in transcriptional complexes and indicate a divergence in functions of Lhx3/4 and Isl1/2. The formation of weaker Lhx·Isl complexes would likely be masked by the availability of the other Lhx·Isl complexes in postmitotic motor neurons.
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Structural Basis for Partial Redundancy in a Class of Transcription Factors, the LIM Homeodomain Proteins, in
2011Co-Authors: M.s. Gadd, Mugdha Bhati, J. Mitchell Guss, Cy M. Jeffries, Jill Trewhella, David B. Langley, Jacqueline M MatthewsAbstract:Combinations of LIM Homeodomain Proteins form a transcriptional “LIM code” to direct the specification of neural cell types. Two paralogous pairs of LIM Homeodomain Proteins, LIM homeobox protein 3/4 (Lhx3/Lhx4) and Islet-1/2 (Isl1/ Isl2), are expressed in developing ventral motor neurons. Lhx3 and Isl1 interact within a well characterized transcriptional complex that triggers motor neuron development, but it was not known whether Lhx4 and Isl2 could participate in equivalent complexes. We have identified an Lhx3-binding domain (LBD) in Isl2 based on sequence homology with the Isl1LBD and show that both Isl2LBD and Isl1LBD can bind each of Lhx3 and Lhx4. X-ray crystal- and small-angle x-ray scattering-derived solution structures of an Lhx4�Isl2 complex exhibit many similarities with that of Lhx3�Isl1; however, structural differences supported by mutagenic studies reveal differences in the mechanisms of binding. Differences in binding have implications for the mode of exchange of protein partners in transcriptional complexes and indicate a divergence in functions of Lhx3/4 and
Jeffrey H Lawrence - One of the best experts on this subject based on the ideXlab platform.
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activation of stem cell specific genes by hoxa9 and hoxa10 Homeodomain Proteins in cd34 human cord blood cells
Stem Cells, 2005Co-Authors: Christina M Ferrell, Corey Largman, Sheri T Dorsam, Hideaki Ohta, Keith R Humphries, Mika K Derynck, Christopher M Haqq, Jeffrey H LawrenceAbstract:There is growing evidence for a role of HOX Homeodomain Proteins in normal hematopoiesis. Several HOX genes, including HOXA9 and HOXA10, are expressed in primitive hematopoietic cells, implying a role in early hematopoietic differentiation. To identify potential target genes of these two closely related transcription factors, human CD34+ umbilical cord blood cells were transduced with vectors expressing either HOXA9 or HOXA10 and analyzed with cDNA micro-arrays. Statistical analysis using significance analysis of microarrays revealed a common signature of several hundred genes, demonstrating that the transcriptomes of HOXA9 and HOXA10 largely overlap in this cellular context. Seven genes that were upregulated by both HOX Proteins were validated by real-time reverse transcription polymerase chain reaction. HOXA9 and HOXA10 showed positive regulation of genes in the Wnt pathway, including Wnt10B and two Wnt receptors Frizzled 1 and Frizzled 5, an important pathway for hematopoietic stem cell (HSC) self-renewal. Other validated genes included v-ets-related gene (ERG), Iroquois 3 (IRX3), aldehyde dehydrogenase 1 (ALDH1), and very long–chain acyl-CoA synthetase homolog 1 (VLCS-H1). GenMAPP (Gene Micro Array Pathway Profiler) analysis indicated that HOXA10 repressed expression of several genes involved in heme biosynthesis and three globin genes, indicating a general suppression of erythroid differentiation. A number of genes regulated by HOXA9 and HOXA10 are expressed in normal HSC populations.