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Kalis AK, Sterrett MC, Armstrong C, Ballmer A, Burkstrand K, Chilson E, Emlen E, Ferrer E, Loeb S, Olin T, Tran K, Wheeler A, Ross Wolff J. Hox proteins interact to pattern neuronal subtypes in Caenorhabditis elegans males. Genetics 2022; 220:iyac010. [PMID: 35137058 PMCID: PMC8982040 DOI: 10.1093/genetics/iyac010] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 01/10/2022] [Indexed: 11/14/2022] Open
Abstract
Hox transcription factors are conserved regulators of neuronal subtype specification on the anteroposterior axis in animals, with disruption of Hox gene expression leading to homeotic transformations of neuronal identities. We have taken advantage of an unusual mutation in the Caenorhabditis elegans Hox gene lin-39, lin-39(ccc16), which transforms neuronal fates in the C. elegans male ventral nerve cord in a manner that depends on a second Hox gene, mab-5. We have performed a genetic analysis centered around this homeotic allele of lin-39 in conjunction with reporters for neuronal target genes and protein interaction assays to explore how LIN-39 and MAB-5 exert both flexibility and specificity in target regulation. We identify cis-regulatory modules in neuronal reporters that are both region-specific and Hox-responsive. Using these reporters of neuronal subtype, we also find that the lin-39(ccc16) mutation disrupts neuronal fates specifically in the region where lin-39 and mab-5 are coexpressed, and that the protein encoded by lin-39(ccc16) is active only in the absence of mab-5. Moreover, the fates of neurons typical to the region of lin-39-mab-5 coexpression depend on both Hox genes. Our genetic analysis, along with evidence from Bimolecular Fluorescence Complementation protein interaction assays, supports a model in which LIN-39 and MAB-5 act at an array of cis-regulatory modules to cooperatively activate and to individually activate or repress neuronal gene expression, resulting in regionally specific neuronal fates.
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Affiliation(s)
- Andrea K Kalis
- Department of Biology, St. Catherine University, St. Paul, MN 55105, USA
| | - Maria C Sterrett
- Department of Biology, Carleton College, Northfield, MN 55057, USA
| | - Cecily Armstrong
- Department of Biology, St. Catherine University, St. Paul, MN 55105, USA
| | | | - Kylie Burkstrand
- Department of Biology, St. Catherine University, St. Paul, MN 55105, USA
| | - Elizabeth Chilson
- Department of Biology, St. Catherine University, St. Paul, MN 55105, USA
| | - Estee Emlen
- Department of Biology, Carleton College, Northfield, MN 55057, USA
| | - Emma Ferrer
- Department of Biology, Carleton College, Northfield, MN 55057, USA
| | - Seanna Loeb
- Department of Biology, St. Catherine University, St. Paul, MN 55105, USA
| | - Taylor Olin
- Department of Biology, St. Catherine University, St. Paul, MN 55105, USA
| | - Kevin Tran
- Department of Biology, Carleton College, Northfield, MN 55057, USA
| | - Andrew Wheeler
- Department of Biology, Carleton College, Northfield, MN 55057, USA
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The human HOXA9 protein uses paralog-specific residues of the homeodomain to interact with TALE-class cofactors. Sci Rep 2019; 9:5664. [PMID: 30952900 PMCID: PMC6450960 DOI: 10.1038/s41598-019-42096-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 03/22/2019] [Indexed: 12/15/2022] Open
Abstract
HOX proteins interact with PBX and MEIS cofactors, which belong to the TALE-class of homeodomain (HD)-containing transcription factors. Although the formation of HOX-PBX complexes depends on a unique conserved HOX motif called hexapeptide (HX), the additional presence of MEIS induces a remodeling of the interaction, leading to a global dispensability of the HX motif for trimeric complex formation in the large majority of HOX proteins. In addition, it was shown that the anterior HOXB3 and central HOXA7 and HOXC8 proteins could use different alternative TALE interaction motifs, with or without the HX motif, depending on the DNA-binding site and cell context. Here we dissected the molecular interaction properties of the human posterior HOXA9 protein with its TALE cofactors, PBX1 and MEIS1. Analysis was performed on different DNA-binding sites in vitro and by doing Bimolecular Fluorescence Complementation (BiFC) in different cell lines. Notably, we observed that the HOXA9-TALE interaction relies consistently on the redundant activity of the HX motif and two paralog-specific residues of the HOXA9 HD. Together with previous work, our results show that HOX proteins interact with their generic TALE cofactors through various modalities, ranging from unique and context-independent to versatile and context-dependent TALE binding interfaces.
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Ortiz-Lombardia M, Foos N, Maurel-Zaffran C, Saurin AJ, Graba Y. Hox functional diversity: Novel insights from flexible motif folding and plastic protein interaction. Bioessays 2017; 39. [PMID: 28092121 DOI: 10.1002/bies.201600246] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
How the formidable diversity of forms emerges from developmental and evolutionary processes is one of the most fascinating questions in biology. The homeodomain-containing Hox proteins were recognized early on as major actors in diversifying animal body plans. The molecular mechanisms underlying how this transcription factor family controls a large array of context- and cell-specific biological functions is, however, still poorly understood. Clues to functional diversity have emerged from studies exploring how Hox protein activity is controlled through interactions with PBC class proteins, also evolutionary conserved HD-containing proteins. Recent structural data and molecular dynamic simulations add further mechanistic insights into Hox protein mode of action, suggesting that flexible folding of protein motifs allows for plastic protein interaction. As we discuss in this review, these findings define a novel type of Hox-PBC interaction, weak and dynamic instead of strong and static, hence providing novel clues to understanding Hox transcriptional specificity and diversity.
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Affiliation(s)
- Miguel Ortiz-Lombardia
- Aix-Marseille-Université, CNRS UMR 7257, AFMB, Marseille, France.,Aix-Marseille-Université, CNRS UMR 7256, AFMB, Marseille, France
| | - Nicolas Foos
- Aix-Marseille-Université, CNRS UMR 7257, AFMB, Marseille, France
| | | | - Andrew J Saurin
- Aix-Marseille-Université, CNRS UMR 7288, case 907, IBDM, Marseille, France
| | - Yacine Graba
- Aix-Marseille-Université, CNRS UMR 7288, case 907, IBDM, Marseille, France
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Abstract
Metazoans encode clusters of paralogous Hox genes that are critical for proper development of the body plan. However, there are a number of unresolved issues regarding how paralogous Hox factors achieve specificity to control distinct cell fates. First, how do Hox paralogs, which have very similar DNA binding preferences in vitro, drive different transcriptional programs in vivo? Second, the number of potential Hox binding sites within the genome is vast compared to the number of sites bound. Hence, what determines where in the genome Hox factors bind? Third, what determines whether a Hox factor will activate or repress a specific target gene? Here, we review the current evidence that is beginning to shed light onto these questions. In particular, we highlight how cooperative interactions with other transcription factors (especially PBC and HMP proteins) and the sequences of cis-regulatory modules provide a basis for the mechanisms of Hox specificity. We conclude by integrating a number of the concepts described throughout the review in a case study of a highly interrogated Drosophila cis-regulatory module named “The Distal-less Conserved Regulatory Element” (DCRE).
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Affiliation(s)
- Arya Zandvakili
- Molecular and Developmental Biology Graduate Program, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
- Medical-Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA;
| | - Brian Gebelein
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
- Correspondence: ; Tel.: +1-513-636-3366
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Merabet S, Mann RS. To Be Specific or Not: The Critical Relationship Between Hox And TALE Proteins. Trends Genet 2016; 32:334-347. [PMID: 27066866 DOI: 10.1016/j.tig.2016.03.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 03/09/2016] [Accepted: 03/10/2016] [Indexed: 10/22/2022]
Abstract
Hox proteins are key regulatory transcription factors that act in different tissues of the embryo to provide specific spatial and temporal coordinates to each cell. These patterning functions often depend on the presence of the TALE-homeodomain class cofactors, which form cooperative DNA-binding complexes with all Hox proteins. How this family of cofactors contributes to the highly diverse and specific functions of Hox proteins in vivo remains an important unsolved question. We review here the most recent advances in understanding the molecular mechanisms underlying Hox-TALE function. In particular, we discuss the role of DNA shape, DNA-binding affinity, and protein-protein interaction flexibility in dictating Hox-TALE specificity. We propose several models to explain how these mechanisms are integrated with each other in the context of the many distinct functions that Hox and TALE factors carry out in vivo.
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Affiliation(s)
- Samir Merabet
- Institut de Génomique Fonctionnelle de Lyon, Centre National de Recherche Scientifique, Ecole Normale Supérieure de Lyon, France.
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Martin A, Serano JM, Jarvis E, Bruce HS, Wang J, Ray S, Barker CA, O'Connell LC, Patel NH. CRISPR/Cas9 Mutagenesis Reveals Versatile Roles of Hox Genes in Crustacean Limb Specification and Evolution. Curr Biol 2015; 26:14-26. [PMID: 26687626 DOI: 10.1016/j.cub.2015.11.021] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/09/2015] [Accepted: 11/09/2015] [Indexed: 12/11/2022]
Abstract
Crustaceans possess a diverse array of specialized limbs. Although shifts in Hox gene expression domains have been postulated to play a role in generating this limb diversity, little functional data have been provided to understand the precise roles of Hox genes during crustacean development. We used a combination of CRISPR/Cas9-targeted mutagenesis and RNAi knockdown to decipher the function of the six Hox genes expressed in the developing mouth and trunk of the amphipod Parhyale hawaiensis. These experimentally manipulated animals display specific and striking homeotic transformations. We found that abdominal-A (abd-A) and Abdominal-B (Abd-B) are required for proper posterior patterning, with knockout of Abd-B resulting in an animal with thoracic type legs along what would have been an abdomen, and abd-A disruption generating a simplified body plan characterized by a loss of specialization in both abdominal and thoracic appendages. In the thorax, Ubx is necessary for gill development and for repression of gnathal fate, and Antp dictates claw morphology. In the mouth, Scr and Antp confer the part-gnathal, part-thoracic hybrid identity of the maxilliped, and Scr and Dfd prevent antennal identity in posterior head segments. Our results allow us to define the role Hox genes play in specifying each appendage type in Parhyale, including the modular nature by which some appendages are patterned by Hox gene inputs. In addition, we define how changes in Hox gene expression have generated morphological differences between crustacean species. Finally, we also highlight the utility of CRISPR/Cas9-based somatic mutagenesis in emerging model organisms.
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Affiliation(s)
- Arnaud Martin
- Department of Molecular Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200 USA
| | - Julia M Serano
- Department of Molecular Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200 USA
| | - Erin Jarvis
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3140 USA
| | - Heather S Bruce
- Department of Molecular Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200 USA
| | - Jennifer Wang
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3140 USA
| | - Shagnik Ray
- Department of Molecular Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200 USA
| | - Carryn A Barker
- Department of Molecular Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200 USA
| | - Liam C O'Connell
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3140 USA
| | - Nipam H Patel
- Department of Molecular Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200 USA; Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3140 USA.
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Bürglin TR, Affolter M. Homeodomain proteins: an update. Chromosoma 2015; 125:497-521. [PMID: 26464018 PMCID: PMC4901127 DOI: 10.1007/s00412-015-0543-8] [Citation(s) in RCA: 258] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 09/20/2015] [Accepted: 09/21/2015] [Indexed: 12/17/2022]
Abstract
Here, we provide an update of our review on homeobox genes that we wrote together with Walter Gehring in 1994. Since then, comprehensive surveys of homeobox genes have become possible due to genome sequencing projects. Using the 103 Drosophila homeobox genes as example, we present an updated classification. In animals, there are 16 major classes, ANTP, PRD, PRD-LIKE, POU, HNF, CUT (with four subclasses: ONECUT, CUX, SATB, and CMP), LIM, ZF, CERS, PROS, SIX/SO, plus the TALE superclass with the classes IRO, MKX, TGIF, PBC, and MEIS. In plants, there are 11 major classes, i.e., HD-ZIP (with four subclasses: I to IV), WOX, NDX, PHD, PLINC, LD, DDT, SAWADEE, PINTOX, and the two TALE classes KNOX and BEL. Most of these classes encode additional domains apart from the homeodomain. Numerous insights have been obtained in the last two decades into how homeodomain proteins bind to DNA and increase their specificity by interacting with other proteins to regulate cell- and tissue-specific gene expression. Not only protein-DNA base pair contacts are important for proper target selection; recent experiments also reveal that the shape of the DNA plays a role in specificity. Using selected examples, we highlight different mechanisms of homeodomain protein-DNA interaction. The PRD class of homeobox genes was of special interest to Walter Gehring in the last two decades. The PRD class comprises six families in Bilateria, and tinkers with four different motifs, i.e., the PAIRED domain, the Groucho-interacting motif EH1 (aka Octapeptide or TN), the homeodomain, and the OAR motif. Homologs of the co-repressor protein Groucho are also present in plants (TOPLESS), where they have been shown to interact with small amphipathic motives (EAR), and in yeast (TUP1), where we find an EH1-like motif in MATα2.
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Affiliation(s)
- Thomas R. Bürglin
- />Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
- />Department of Biomedicine, University of Basel, Mattenstrasse 28, 4058 Basel, Switzerland
| | - Markus Affolter
- />Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
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Merabet S, Galliot B. The TALE face of Hox proteins in animal evolution. Front Genet 2015; 6:267. [PMID: 26347770 PMCID: PMC4539518 DOI: 10.3389/fgene.2015.00267] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 07/31/2015] [Indexed: 01/22/2023] Open
Abstract
Hox genes are major regulators of embryonic development. One of their most conserved functions is to coordinate the formation of specific body structures along the anterior-posterior (AP) axis in Bilateria. This architectural role was at the basis of several morphological innovations across bilaterian evolution. In this review, we traced the origin of the Hox patterning system by considering the partnership with PBC and Meis proteins. PBC and Meis belong to the TALE-class of homeodomain-containing transcription factors and act as generic cofactors of Hox proteins for AP axis patterning in Bilateria. Recent data indicate that Hox proteins acquired the ability to interact with their TALE partners in the last common ancestor of Bilateria and Cnidaria. These interactions relied initially on a short peptide motif called hexapeptide (HX), which is present in Hox and non-Hox protein families. Remarkably, Hox proteins can also recruit the TALE cofactors by using specific PBC Interaction Motifs (SPIMs). We describe how a functional Hox/TALE patterning system emerged in eumetazoans through the acquisition of SPIMs. We anticipate that interaction flexibility could be found in other patterning systems, being at the heart of the astonishing morphological diversity observed in the animal kingdom.
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Affiliation(s)
- Samir Merabet
- Centre National de Recherche Scientifique, Institut de Génomique Fonctionnelle de Lyon Lyon, France ; Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon Lyon, France
| | - Brigitte Galliot
- Department of Genetics and Evolution, Faculty of Science, Institute of Genetics and Genomics in Geneva, University of Geneva Geneva, Switzerland
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Abstract
Hox proteins gain specificity by interacting with TALE-class cofactors. In a recent issue of Cell and in this issue of Developmental Cell, Crocker et al. (2015) and Amin et al. (2015), respectively, demonstrate that non-canonical Hox/TALE binding sequences play a major role in the regionalized regulation of target gene expression in vivo.
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Affiliation(s)
- Samir Merabet
- Institut de Génomique Fonctionnelle de Lyon (IGFL), UMR5242, ENS Lyon, 46 Allée d'Italie, 69007 Lyon, France.
| | - Ingrid Lohmann
- Department of Developmental Biology, Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, D-69120 Heidelberg, Germany.
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