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Martinez P, Bailly X, Sprecher SG, Hartenstein V. The Acoel nervous system: morphology and development. Neural Dev 2024; 19:9. [PMID: 38907301 PMCID: PMC11191258 DOI: 10.1186/s13064-024-00187-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 06/15/2024] [Indexed: 06/23/2024] Open
Abstract
Acoel flatworms have played a relevant role in classical (and current) discussions on the evolutionary origin of bilaterian animals. This is mostly derived from the apparent simplicity of their body architectures. This tenet has been challenged over the last couple of decades, mostly because detailed studies of their morphology and the introduction of multiple genomic technologies have unveiled a complexity of cell types, tissular arrangements and patterning mechanisms that were hidden below this 'superficial' simplicity. One tissue that has received a particular attention has been the nervous system (NS). The combination of ultrastructural and single cell methodologies has revealed unique cellular diversity and developmental trajectories for most of their neurons and associated sensory systems. Moreover, the great diversity in NS architectures shown by different acoels offers us with a unique group of animals where to study key aspects of neurogenesis and diversification od neural systems over evolutionary time.In this review we revisit some recent developments in the characterization of the acoel nervous system structure and the regulatory mechanisms that contribute to their embryological development. We end up by suggesting some promising avenues to better understand how this tissue is organized in its finest cellular details and how to achieve a deeper knowledge of the functional roles that genes and gene networks play in its construction.
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Affiliation(s)
- Pedro Martinez
- Departament de Genètica, Microbiologia I Estadística, Universitat de Barcelona, Av. Diagonal 643, Barcelona, 08028, Spain.
- ICREA (Institut Català de Recerca I Estudis Avancats), Barcelona, Spain.
| | - Xavier Bailly
- Station Biologique de Roscoff, Multicellular Marine Models (M3) Team, FR2424, CNRS / Sorbonne Université - Place Georges Teissier, Roscoff, 29680, France
| | - Simon G Sprecher
- Department of Biology, University of Fribourg, 10, Ch. Du Musée, Fribourg, 1700, Switzerland
| | - Volker Hartenstein
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
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Luna-Arias JP, Castro-Muñozledo F. Participation of the TBP-associated factors (TAFs) in cell differentiation. J Cell Physiol 2024; 239:e31167. [PMID: 38126142 DOI: 10.1002/jcp.31167] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/04/2023] [Accepted: 11/27/2023] [Indexed: 12/23/2023]
Abstract
The understanding of the mechanisms that regulate gene expression to establish differentiation programs and determine cell lineages, is one of the major challenges in Developmental Biology. Besides the participation of tissue-specific transcription factors and epigenetic processes, the role of general transcription factors has been ignored. Only in recent years, there have been scarce studies that address this issue. Here, we review the studies on the biological activity of some TATA-box binding protein (TBP)-associated factors (TAFs) during the proliferation of stem/progenitor cells and their involvement in cell differentiation. Particularly, the accumulated evidence suggests that TAF4, TAF4b, TAF7L, TAF8, TAF9, and TAF10, among others, participate in nervous system development, adipogenesis, myogenesis, and epidermal differentiation; while TAF1, TAF7, TAF15 may be involved in the regulation of stem cell proliferative abilities and cell cycle progression. On the other hand, evidence suggests that TBP variants such as TBPL1 and TBPL2 might be regulating some developmental processes such as germ cell maturation and differentiation, myogenesis, or ventral specification during development. Our analysis shows that it is necessary to study in greater depth the biological function of these factors and its participation in the assembly of specific transcription complexes that contribute to the differential gene expression that gives rise to the great diversity of cell types existing in an organism. The understanding of TAFs' regulation might lead to the development of new therapies for patients which suffer from mutations, alterations, and dysregulation of these essential elements of the transcriptional machinery.
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Affiliation(s)
- Juan Pedro Luna-Arias
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN, México City, Mexico
| | - Federico Castro-Muñozledo
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN, México City, Mexico
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3
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Baker NE. Founding the Wnt gene family: How wingless was found to be a positional signal and oncogene homolog. Bioessays 2024; 46:e2300156. [PMID: 38214693 DOI: 10.1002/bies.202300156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 11/27/2023] [Accepted: 11/29/2023] [Indexed: 01/13/2024]
Abstract
The Wnt family of developmental regulators were named after the Drosophila segmentation gene wingless and the murine proto-oncogene int-1. Homology between these two genes connected oncogenesis to cell-cell signals in development. I review how wingless was initially characterized, and cloned, as part of the quest to identify developmental cell-to-cell signals, based on predictions of the Positional Information Model, and on the properties of homeotic and segmentation gene mutants. The requirements and cell-nonautonomy of wingless in patterning multiple embryonic and adult structures solidified its status as a candidate signaling molecule. The physical location of wingless mutations and transcription unit defined the gene and its developmental transcription pattern. When the Drosophila homolog of int-1 was then isolated, and predicted to encode a secreted proto-oncogene homolog, it's identity to the wingless gene confirmed that a developmental cell-cell signal had been identified and connected cancer to development.
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Affiliation(s)
- Nicholas E Baker
- Department of Genetics, Department of Developmental and Molecular Biology, Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York, USA
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Levin M, Martyniuk CJ. The bioelectric code: An ancient computational medium for dynamic control of growth and form. Biosystems 2018; 164:76-93. [PMID: 28855098 PMCID: PMC10464596 DOI: 10.1016/j.biosystems.2017.08.009] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/20/2017] [Accepted: 08/22/2017] [Indexed: 12/19/2022]
Abstract
What determines large-scale anatomy? DNA does not directly specify geometrical arrangements of tissues and organs, and a process of encoding and decoding for morphogenesis is required. Moreover, many species can regenerate and remodel their structure despite drastic injury. The ability to obtain the correct target morphology from a diversity of initial conditions reveals that the morphogenetic code implements a rich system of pattern-homeostatic processes. Here, we describe an important mechanism by which cellular networks implement pattern regulation and plasticity: bioelectricity. All cells, not only nerves and muscles, produce and sense electrical signals; in vivo, these processes form bioelectric circuits that harness individual cell behaviors toward specific anatomical endpoints. We review emerging progress in reading and re-writing anatomical information encoded in bioelectrical states, and discuss the approaches to this problem from the perspectives of information theory, dynamical systems, and computational neuroscience. Cracking the bioelectric code will enable much-improved control over biological patterning, advancing basic evolutionary developmental biology as well as enabling numerous applications in regenerative medicine and synthetic bioengineering.
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Affiliation(s)
- Michael Levin
- Allen Discovery Center at Tufts University, Biology Department, Tufts University, 200 Boston Avenue, Suite 4600 Medford, MA 02155, USA.
| | - Christopher J Martyniuk
- Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida Genetics Institute, Interdisciplinary Program in Biomedical Sciences Neuroscience, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32611, USA
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Zaidi MS, Hassan A, Almogbel E. Mayer-Rokitansky-Küster-Hauser Syndrome In A Young Woman. AACE Clin Case Rep 2017. [DOI: 10.4158/ep151105.cr] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Liu C, Zhao F, Yan J, Liu C, Liu S, Chen S. Transcriptome Sequencing and De Novo Assembly of Golden Cuttlefish Sepia esculenta Hoyle. Int J Mol Sci 2016; 17:ijms17101749. [PMID: 27782082 PMCID: PMC5085775 DOI: 10.3390/ijms17101749] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 10/12/2016] [Accepted: 10/12/2016] [Indexed: 11/16/2022] Open
Abstract
Golden cuttlefish Sepia esculenta Hoyle is an economically important cephalopod species. However, artificial hatching is currently challenged by low survival rate of larvae due to abnormal embryonic development. Dissecting the genetic foundation and regulatory mechanisms in embryonic development requires genomic background knowledge. Therefore, we carried out a transcriptome sequencing on Sepia embryos and larvae via mRNA-Seq. 32,597,241 raw reads were filtered and assembled into 98,615 unigenes (N50 length at 911 bp) which were annotated in NR database, GO and KEGG databases respectively. Digital gene expression analysis was carried out on cleavage stage embryos, healthy larvae and malformed larvae. Unigenes functioning in cell proliferation exhibited higher transcriptional levels at cleavage stage while those related to animal disease and organ development showed increased transcription in malformed larvae. Homologs of key genes in regulatory pathways related to early development of animals were identified in Sepia. Most of them exhibit higher transcriptional levels in cleavage stage than larvae, suggesting their potential roles in embryonic development of Sepia. The de novo assembly of Sepia transcriptome is fundamental genetic background for further exploration in Sepia research. Our demonstration on the transcriptional variations of genes in three developmental stages will provide new perspectives in understanding the molecular mechanisms in early embryonic development of cuttlefish.
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Affiliation(s)
- Changlin Liu
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China.
| | - Fazhen Zhao
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China.
| | - Jingping Yan
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China.
| | - Chunsheng Liu
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China.
| | - Siwei Liu
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China.
| | - Siqing Chen
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China.
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Mayer–Rokitansky–Küster–Hauser (MRKH) syndrome: A historical perspective. Gene 2015; 555:33-40. [DOI: 10.1016/j.gene.2014.09.045] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 09/19/2014] [Accepted: 09/21/2014] [Indexed: 12/15/2022]
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Merabet S, Dard A. Tracking context-specific transcription factors regulating hox activity. Dev Dyn 2013; 243:16-23. [PMID: 23794379 DOI: 10.1002/dvdy.24002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 06/07/2013] [Accepted: 06/11/2013] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Hox proteins are key developmental regulators involved in almost every embryonic tissue for specifying cell fates along longitudinal axes or during organ formation. It is thought that the panoply of Hox activities relies on interactions with tissue-, stage-, and/or cell-specific transcription factors. High-throughput approaches in yeast or cell culture systems have shown that Hox proteins bind to various types of nuclear and cytoplasmic components, illustrating their remarkable potential to influence many different cell regulatory processes. However, these approaches failed to identify a relevant number of context-specific transcriptional partners, suggesting that these interactions are hard to uncover in non-physiological conditions. Here we discuss this problematic. RESULTS In this review, we present intrinsic Hox molecular signatures that are probably involved in multiple (yet specific) interactions with transcriptional partners. We also recapitulate the current knowledge on Hox cofactors, highlighting the difficulty to tracking context-specific cofactors through traditional large-scale approaches. CONCLUSION We propose experimental approaches that will allow a better characterisation of interaction networks underlying Hox contextual activities in the next future.
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Interplay between Misplaced Müllerian-Derived Stem Cells and Peritoneal Immune Dysregulation in the Pathogenesis of Endometriosis. Obstet Gynecol Int 2013; 2013:527041. [PMID: 23843796 PMCID: PMC3697788 DOI: 10.1155/2013/527041] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 05/19/2013] [Accepted: 05/28/2013] [Indexed: 12/26/2022] Open
Abstract
In the genetic regulation of Müllerian structures development, a key role is played by Hoxa and Wnt clusters, because they lead the transcription of different genes according to the different phases of the organogenesis, addressing correctly cell-to-cell interactions, allowing, finally, the physiologic morphogenesis. Accumulating evidence is suggesting that dysregulation of Wnt and/or Hox genes may affect cell migration during organogenesis and differentiation of Müllerian structures of the female reproductive tract, with possible dislocation and dissemination of primordial endometrial stem cells in ectopic regions, which have high plasticity to differentiation. We hypothesize that during postpubertal age, under the influence of different stimuli, these misplaced and quiescent ectopic endometrial cells could acquire new phenotype, biological functions, and immunogenicity. So, these kinds of cells may differentiate, specializing in epithelium, glands, and stroma to form a functional ectopic endometrial tissue. This may provoke a breakdown in the peritoneal cavity homeostasis, with the consequent processes of immune alteration, documented by peripheral mononuclear cells recruitment and secretion of inflammatory cytokines in early phases and of angiogenic and fibrogenic cytokines in the late stages of the disease.
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Veltmaat JM, Ramsdell AF, Sterneck E. Positional variations in mammary gland development and cancer. J Mammary Gland Biol Neoplasia 2013; 18:179-88. [PMID: 23666389 PMCID: PMC3691492 DOI: 10.1007/s10911-013-9287-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Accepted: 04/26/2013] [Indexed: 12/24/2022] Open
Abstract
Most mammals develop their mammary glands in pairs of which the two counterparts are symmetrically displaced away from the ventral midline. Based on this symmetry and the same functional outcome as a milk-producing organ, the mammary glands are easily presumed to be mere copies of one another. Based on our analysis of published data with inclusion of new results related to mammary development and pathology in mice, we argue that this presumption is incorrect: Between and within pairs, mammary glands differ from one another, and tumor incidence and biology depend on the position along the anterior-posterior and the left-right axis as well. This insight has implications for experimental designs with mouse models and for data extrapolation between mammary glands within and between species. We suggest that improved documentation of location-specific mammary gland features will lead to more insights into the molecular mechanisms of mammary gland development and cancer biology in both mice and humans.
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Affiliation(s)
- Jacqueline M. Veltmaat
- />Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Singapore, 138673 Singapore
| | - Ann F. Ramsdell
- />Department of Cell Biology and Anatomy and Program in Women’s and Gender Studies, College of Arts and Sciences, University of South Carolina School of Medicine, Columbia, SC 29208 USA
- />Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, 173 Ashley Avenue, BSB Room 601, Charleston, SC 29425 USA
| | - Esta Sterneck
- />National Cancer Institute, Center for Cancer Research, PO Box B, Frederick, MD 21702-1201 USA
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11
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Kalis AK, Murphy MW, Zarkower D. EGL-5/ABD-B plays an instructive role in male cell fate determination in the C. elegans somatic gonad. Dev Biol 2010; 344:827-35. [PMID: 20553900 PMCID: PMC2921588 DOI: 10.1016/j.ydbio.2010.05.516] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 05/26/2010] [Accepted: 05/28/2010] [Indexed: 01/15/2023]
Abstract
Hox genes of the Abdominal-B (Abd-B) class regulate gonadal development in diverse metazoans. Here we have investigated the role of the Abd-B homolog egl-5 in C. elegans gonadal development. Previous work showed that egl-5 is required male-specifically in the gonad and that mutant gonads are highly dysgenic and possibly feminized. We have used sex-specific gonadal reporter genes to confirm that the gonads of egl-5 males are extensively feminized. Sex-specific expression of egl-5 requires the global sex determination gene tra-1 and the gonadal masculinizing gene fkh-6, but mutagenesis of a short male gonadal enhancer element in egl-5 suggested that this regulation is indirect. Ectopic expression of EGL-5 in hermaphrodites is sufficient to induce male gonadal gene expression, indicating that EGL-5 plays an instructive role in male gonadal fate determination. EGL-5 acts in parallel with a Wnt/beta-catenin pathway to regulate male gonadal fates and can physically interact with the Wnt pathway transcription factor POP-1 and modulate activity of a POP-1 dependent reporter gene. We propose that EGL-5 imparts sex-specific function on POP-1 by recruiting it to male-specific gonadal target genes.
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Affiliation(s)
- Andrea K. Kalis
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455
| | - Mark W. Murphy
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455
| | - David Zarkower
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455
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12
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Volpe MV, Chung E, Ulm JP, Gilchrist BF, Ralston S, Wang KT, Nielsen HC. Aberrant cell adhesion molecule expression in human bronchopulmonary sequestration and congenital cystic adenomatoid malformation. Am J Physiol Lung Cell Mol Physiol 2009; 297:L143-52. [PMID: 19411307 DOI: 10.1152/ajplung.90618.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In many organs, integrins and cadherins are partly regulated by Hox genes, but their interactions in airway morphogenesis and congenital lung diseases are unknown. We previously showed that the Hox protein HoxB5 is abnormally increased in bronchopulmonary sequestration (BPS) and congenital cystic adenomatoid malformation (CCAM), congenital lung lesions with abnormal airway branching. We now report on alpha(2)-, alpha(3)-, and beta(1)-integrin and E-cadherin expression in normal human lung and in BPS and CCAM tissue previously shown to have abnormal HoxB5 expression and on the relationship of cell adhesion molecule expression to Hoxb5 regulation. alpha(2)-, alpha(3)-, and beta(1)-integrins and E-cadherin expression in normal human lung and BPS and CCAM were evaluated using Western blot and immunohistochemistry. Fetal mouse lung fibroblasts with Hoxb5-specific siRNA downregulation were evaluated for alpha(2)-integrin protein levels by Western blot. Compared with normal human lung, a previously undetected alpha(2)-integrin isoform potentially lacking essential cytoplasmic sequences was significantly increased in BPS and CCAM, and alpha(2)-integrin spatial and cellular expression was more intense. E-cadherin protein levels were also significantly increased, whereas alpha(3) increased in CCAM compared with canalicular, but not with alveolar, stage lung. beta(1)-integrin levels were unchanged. We conclude that in BPS and CCAM, altered alpha(2)-integrin cytoplasmic signaling contributes to abnormal cellular behavior in these lung lesions. Aberrant cell adhesion molecule and Hox protein regulation are likely part of the mechanism involved in the development of BPS and CCAM.
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Affiliation(s)
- Maryann V Volpe
- Department of Pediatrics, Division of Newborn Medicine, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
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Abstract
When stem cells divide, they can generate progeny with the same developmental potential as the original cell, a process referred to as self-renewal. Self-renewal is driven intrinsically by gene expression in a cell-type-specific manner and is modulated through interactions with extrinsic cues from the environment, such as growth factors. However, despite the prevalence of the term self-renewal in the scientific literature, this process has not been defined at the molecular level. Haematopoietic stem cells are an excellent model for the study of self-renewal because they can be isolated prospectively, manipulated relatively easily and assessed by using well-defined assays. Establishing the principles of self-renewal in haematopoietic stem cells will lead to insights into the mechanisms of self-renewal in other tissues.
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Temperature-induced switch to the pathogenic yeast form of Histoplasma capsulatum requires Ryp1, a conserved transcriptional regulator. Proc Natl Acad Sci U S A 2008; 105:4880-5. [PMID: 18339808 DOI: 10.1073/pnas.0710448105] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Histoplasma capsulatum, a fungal pathogen of humans, switches from a filamentous spore-forming mold in the soil to a pathogenic budding-yeast form in the human host. This morphologic switch, which is exhibited by H. capsulatum and a group of evolutionarily related fungal pathogens, is regulated by temperature. Using insertional mutagenesis, we identified a gene, RYP1 (required for yeast phase growth), which is required for yeast-form growth at 37 degrees C. ryp1 mutants are constitutively filamentous irrespective of temperature. Ryp1 is a member of a family of fungal proteins that includes Wor1, a master transcriptional regulator of the white-opaque transition required for mating in Candida albicans. Ryp1 associates with its own upstream regulatory region, consistent with a direct role in transcriptional control, and both the protein and its transcript accumulate to high levels in wild-type yeast-phase cells. Microarray analysis demonstrated that Ryp1 is required for the expression of the vast majority of yeast-specific genes, including two genes linked to virulence. Thus, Ryp1 appears to be a critical transcriptional regulator of a temperature-regulated morphologic switch in H. capsulatum.
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Ryan JF, Baxevanis AD. Hox, Wnt, and the evolution of the primary body axis: insights from the early-divergent phyla. Biol Direct 2007; 2:37. [PMID: 18078518 PMCID: PMC2222619 DOI: 10.1186/1745-6150-2-37] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Accepted: 12/13/2007] [Indexed: 11/12/2022] Open
Abstract
The subkingdom Bilateria encompasses the overwhelming majority of animals, including all but four early-branching phyla: Porifera, Ctenophora, Placozoa, and Cnidaria. On average, these early-branching phyla have fewer cell types, tissues, and organs, and are considered to be significantly less specialized along their primary body axis. As such, they present an attractive outgroup from which to investigate how evolutionary changes in the genetic toolkit may have contributed to the emergence of the complex animal body plans of the Bilateria. This review offers an up-to-date glimpse of genome-scale comparisons between bilaterians and these early-diverging taxa. Specifically, we examine these data in the context of how they may explain the evolutionary development of primary body axes and axial symmetry across the Metazoa. Next, we re-evaluate the validity and evolutionary genomic relevance of the zootype hypothesis, which defines an animal by a specific spatial pattern of gene expression. Finally, we extend the hypothesis that Wnt genes may be the earliest primary body axis patterning mechanism by suggesting that Hox genes were co-opted into this patterning network prior to the last common ancestor of cnidarians and bilaterians.
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Affiliation(s)
- Joseph F Ryan
- Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Andreas D Baxevanis
- Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
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16
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Hassan MQ, Tare R, Lee SH, Mandeville M, Weiner B, Montecino M, van Wijnen AJ, Stein JL, Stein GS, Lian JB. HOXA10 controls osteoblastogenesis by directly activating bone regulatory and phenotypic genes. Mol Cell Biol 2007; 27:3337-52. [PMID: 17325044 PMCID: PMC1899966 DOI: 10.1128/mcb.01544-06] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
HOXA10 is necessary for embryonic patterning of skeletal elements, but its function in bone formation beyond this early developmental stage is unknown. Here we show that HOXA10 contributes to osteogenic lineage determination through activation of Runx2 and directly regulates osteoblastic phenotypic genes. In response to bone morphogenic protein BMP2, Hoxa10 is rapidly induced and functions to activate the Runx2 transcription factor essential for bone formation. A functional element with the Hox core motif was characterized for the bone-related Runx2 P1 promoter. HOXA10 also activates other osteogenic genes, including the alkaline phosphatase, osteocalcin, and bone sialoprotein genes, and temporally associates with these target gene promoters during stages of osteoblast differentiation prior to the recruitment of RUNX2. Exogenous expression and small interfering RNA knockdown studies establish that HOXA10 mediates chromatin hyperacetylation and trimethyl histone K4 (H3K4) methylation of these genes, correlating to active transcription. HOXA10 therefore contributes to early expression of osteogenic genes through chromatin remodeling. Importantly, HOXA10 can induce osteoblast genes in Runx2 null cells, providing evidence for a direct role in mediating osteoblast differentiation independent of RUNX2. We propose that HOXA10 activates RUNX2 in mesenchymal cells, contributing to the onset of osteogenesis, and that HOXA10 subsequently supports bone formation by direct regulation of osteoblast phenotypic genes.
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Affiliation(s)
- Mohammad Q Hassan
- Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, MA 01655-0106, USA
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