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Wang H, Chen X, Meng X, Cao Y, Han S, Liu K, Zhao X, Zhao X, Zhang X. The pathogenic mechanism of syndactyly type V identified in a Hoxd13Q50R knock-in mice. Bone Res 2024; 12:21. [PMID: 38561387 PMCID: PMC10984994 DOI: 10.1038/s41413-024-00322-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 01/30/2024] [Accepted: 02/19/2024] [Indexed: 04/04/2024] Open
Abstract
Syndactyly type V (SDTY5) is an autosomal dominant extremity malformation characterized by fusion of the fourth and fifth metacarpals. In the previous publication, we first identified a heterozygous missense mutation Q50R in homeobox domain (HD) of HOXD13 in a large Chinese family with SDTY5. In order to substantiate the pathogenicity of the variant and elucidate the underlying pathogenic mechanism causing limb malformation, transcription-activator-like effector nucleases (TALEN) was employed to generate a Hoxd13Q50R mutant mouse. The mutant mice exhibited obvious limb malformations including slight brachydactyly and partial syndactyly between digits 2-4 in the heterozygotes, and severe syndactyly, brachydactyly and polydactyly in homozygotes. Focusing on BMP2 and SHH/GREM1/AER-FGF epithelial mesenchymal (e-m) feedback, a crucial signal pathway for limb development, we found the ectopically expressed Shh, Grem1 and Fgf8 and down-regulated Bmp2 in the embryonic limb bud at E10.5 to E12.5. A transcriptome sequencing analysis was conducted on limb buds (LBs) at E11.5, revealing 31 genes that exhibited notable disparities in mRNA level between the Hoxd13Q50R homozygotes and the wild-type. These genes are known to be involved in various processes such as limb development, cell proliferation, migration, and apoptosis. Our findings indicate that the ectopic expression of Shh and Fgf8, in conjunction with the down-regulation of Bmp2, results in a failure of patterning along both the anterior-posterior and proximal-distal axes, as well as a decrease in interdigital programmed cell death (PCD). This cascade ultimately leads to the development of syndactyly and brachydactyly in heterozygous mice, and severe limb malformations in homozygous mice. These findings suggest that abnormal expression of SHH, FGF8, and BMP2 induced by HOXD13Q50R may be responsible for the manifestation of human SDTY5.
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Affiliation(s)
- Han Wang
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Department of Medical Genetics, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
- Department of Orthopedics, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100730, China
| | - Xiumin Chen
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Department of Medical Genetics, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Xiaolu Meng
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Department of Medical Genetics, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Yixuan Cao
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Department of Medical Genetics, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Shirui Han
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Department of Medical Genetics, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Keqiang Liu
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Department of Medical Genetics, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Ximeng Zhao
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Department of Medical Genetics, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Xiuli Zhao
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Department of Medical Genetics, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China.
| | - Xue Zhang
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Department of Medical Genetics, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China.
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Atsuta Y, Lee C, Rodrigues AR, Colle C, Tomizawa RR, Lujan EG, Tschopp P, Galan L, Zhu M, Gorham JM, Vannier JP, Seidman CE, Seidman JG, Ros MA, Pourquié O, Tabin CJ. Direct reprogramming of non-limb fibroblasts to cells with properties of limb progenitors. Dev Cell 2024; 59:415-430.e8. [PMID: 38320485 PMCID: PMC10932627 DOI: 10.1016/j.devcel.2023.12.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 09/25/2022] [Accepted: 12/20/2023] [Indexed: 02/08/2024]
Abstract
The early limb bud consists of mesenchymal limb progenitors derived from the lateral plate mesoderm (LPM). The LPM also gives rise to the mesodermal components of the flank and neck. However, the cells at these other levels cannot produce the variety of cell types found in the limb. Taking advantage of a direct reprogramming approach, we find a set of factors (Prdm16, Zbtb16, and Lin28a) normally expressed in the early limb bud and capable of imparting limb progenitor-like properties to mouse non-limb fibroblasts. The reprogrammed cells show similar gene expression profiles and can differentiate into similar cell types as endogenous limb progenitors. The further addition of Lin41 potentiates the proliferation of the reprogrammed cells. These results suggest that these same four factors may play pivotal roles in the specification of endogenous limb progenitors.
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Affiliation(s)
- Yuji Atsuta
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA; Department of Biology, Kyushu University, Fukuoka 819-0395, Japan
| | - ChangHee Lee
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
| | - Alan R Rodrigues
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA; The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Charlotte Colle
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Reiko R Tomizawa
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Ernesto G Lujan
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA; Department of Pathology, Brigham and Women's Hospital, 60 Fenwood Road, Boston, MA 02115, USA
| | - Patrick Tschopp
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA; Zoological Institute, University of Basel, 4051 Basel, Switzerland
| | - Laura Galan
- Instituto de Biomedicina y Biotecnologia de Cantabria, CSIC, SODERCAN- Universidad de Cantabria, 39011 Santander, Spain
| | - Meng Zhu
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Joshua M Gorham
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | | | - Christine E Seidman
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Jonathan G Seidman
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Marian A Ros
- Instituto de Biomedicina y Biotecnologia de Cantabria, CSIC, SODERCAN- Universidad de Cantabria, 39011 Santander, Spain
| | - Olivier Pourquié
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA; Department of Pathology, Brigham and Women's Hospital, 60 Fenwood Road, Boston, MA 02115, USA.
| | - Clifford J Tabin
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
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3
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Tang C, Wang J, Yao M, Ji X, Shi W, Xu C, Zeng LH, Wu X. Hippo signaling activates hedgehog signaling by Taz-driven Gli3 processing. CELL REGENERATION (LONDON, ENGLAND) 2023; 12:3. [PMID: 36720733 PMCID: PMC9889595 DOI: 10.1186/s13619-022-00151-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 11/01/2022] [Indexed: 02/02/2023]
Abstract
The overlapping roles of Hippo and Hedgehog signaling in biological functions and diseases prompt us to investigate their potential interactions. Activation of Hippo signaling enhances the transcriptional output of Hedgehog signaling, and the role of Hippo signaling in regulating Hedgehog signaling relies on the Hippo pathway key effector, Taz. Interestingly, Taz exhibits a gradient expression across the posterior-to-anterior of limb bud mesoderms, similar to Sonic hedgehog (Shh). Importantly, Taz drives PKA to phosphorylate Gli3, resulting in the Gli3 processing into its repressor and attenuation of Hedgehog signaling in the Shh-independent manner. Specifically, Taz deletion in mouse embryonic limb bud mesenchyme not only enhances the Hedgehog signaling but partially restores the phenotypes from Shh deletion in causing severe defects of anteroposterior patterning and digit number and identity. Together, these results uncover Taz-dependent Gli3 processing as a hitherto uncharacterized mechanism controlling Hedgehog signaling, highlighting its cross-regulation by Hippo signaling.
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Affiliation(s)
- Chao Tang
- grid.13402.340000 0004 1759 700XDepartment of Pharmacology, Zhejiang University School of Medicine, 866 Yuhangtang Rd., Hangzhou, 310058 China ,grid.13402.340000 0004 1759 700XNational Clinical Research Center for Child Health of the Children’s Hospital, Zhejiang University School of Medicine, Hangzhou, 310052 China
| | - Jirong Wang
- grid.13402.340000 0004 1759 700XDepartment of Pharmacology, Zhejiang University School of Medicine, 866 Yuhangtang Rd., Hangzhou, 310058 China
| | - Minli Yao
- grid.13402.340000 0004 1759 700XDepartment of Pharmacology, Zhejiang University School of Medicine, 866 Yuhangtang Rd., Hangzhou, 310058 China
| | - Xing Ji
- grid.239552.a0000 0001 0680 8770Translational Research Program in Pediatric Orthopaedics, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104 USA
| | - Wei Shi
- grid.13402.340000 0004 1759 700XDepartment of Pharmacology, Zhejiang University School of Medicine, 866 Yuhangtang Rd., Hangzhou, 310058 China
| | - Chengyun Xu
- grid.13402.340000 0004 1759 700XDepartment of Pharmacology, Zhejiang University School of Medicine, 866 Yuhangtang Rd., Hangzhou, 310058 China
| | - Ling-Hui Zeng
- Department of Pharmacology, Zhejiang University City College, 51 Huzhou Street, Hangzhou, 310015, China.
| | - Ximei Wu
- Department of Pharmacology, Zhejiang University School of Medicine, 866 Yuhangtang Rd., Hangzhou, 310058, China. .,Department of Orthopeadic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310016, China.
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4
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Rana VS, Kitsou C, Dutta S, Ronzetti MH, Zhang M, Bernard Q, Smith AA, Tomás-Cortázar J, Yang X, Wu MJ, Kepple O, Li W, Dwyer JE, Matias J, Baljinnyam B, Oliver JD, Rajeevan N, Pedra JHF, Narasimhan S, Wang Y, Munderloh U, Fikrig E, Simeonov A, Anguita J, Pal U. Dome1-JAK-STAT signaling between parasite and host integrates vector immunity and development. Science 2023; 379:eabl3837. [PMID: 36634189 PMCID: PMC10122270 DOI: 10.1126/science.abl3837] [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: 07/09/2021] [Accepted: 12/08/2022] [Indexed: 01/14/2023]
Abstract
Ancestral signaling pathways serve critical roles in metazoan development, physiology, and immunity. We report an evolutionary interspecies communication pathway involving a central Ixodes scapularis tick receptor termed Dome1, which acquired a mammalian cytokine receptor motif exhibiting high affinity for interferon-gamma (IFN-γ). Host-derived IFN-γ facilitates Dome1-mediated activation of the Ixodes JAK-STAT pathway. This accelerates tick blood meal acquisition and development while upregulating antimicrobial components. The Dome1-JAK-STAT pathway, which exists in most Ixodid tick genomes, regulates the regeneration and proliferation of gut cells-including stem cells-and dictates metamorphosis through the Hedgehog and Notch-Delta networks, ultimately affecting Ixodes vectorial competence. We highlight the evolutionary dependence of I. scapularis on mammalian hosts through cross-species signaling mechanisms that dually influence arthropod immunity and development.
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Affiliation(s)
- Vipin S. Rana
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Chrysoula Kitsou
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Shraboni Dutta
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Michael H. Ronzetti
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Min Zhang
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Quentin Bernard
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Alexis A. Smith
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Julen Tomás-Cortázar
- CIC bioGUNE-BRTA (Basque Research & Technology Alliance), 48160 Derio, Bizkaia, Spain
| | - Xiuli Yang
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Ming-Jie Wu
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Oleksandra Kepple
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Weizhong Li
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Jennifer E. Dwyer
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jaqueline Matias
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Bolormaa Baljinnyam
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | | | - Nallakkandi Rajeevan
- Yale Center for Medical Informatics, Yale University School of Medicine, New Haven, CT, USA
| | - Joao H F Pedra
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sukanya Narasimhan
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Yan Wang
- Mass Spectrometry Facility, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Ulrike Munderloh
- Department of Entomology, University of Minnesota, Minneapolis, MN, USA
| | - Erol Fikrig
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Anton Simeonov
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Juan Anguita
- CIC bioGUNE-BRTA (Basque Research & Technology Alliance), 48160 Derio, Bizkaia, Spain
- Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Bizkaia, Spain
| | - Utpal Pal
- Department of Veterinary Medicine, University of Maryland, College Park, MD, USA
- Virginia-Maryland College of Veterinary Medicine, College Park, MD, USA
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5
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Abstract
The gigantic 32Gb Axolotl genome inspires fascinating questions such as: how such a big genome is organized and packed in nuclei and how regulation of gene transcription can happen over such large genomic distances. Currently, there are many technical challenges when we investigate chromatin architecture in axolotl. For example, probing promoter-enhancer interactions in such a large genome. Chromatin capture methods (e.g., Chromatin Conformation Capture) have been used in a variety of species. The large size of the axolotl nuclei and its genome requires the adaptation of such methods. Here, we describe a detailed protocol for high-throughput genome-wide conformation capture (Hi-C) using axolotl limb cells. This Hi-C library preparation protocol can also be used to prepare libraries from other nonmodel organisms such as Lungfish and Cephalopods. We believe that our protocol could be useful for a variety of animal systems including other salamanders.
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Affiliation(s)
- Akane Kawaguchi
- IMP (Research Institute of Molecular Pathology), Vienna, Austria
| | - Elly M Tanaka
- IMP (Research Institute of Molecular Pathology), Vienna, Austria.
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Khateb M, Perovanovic J, Ko KD, Jiang K, Feng X, Acevedo-Luna N, Chal J, Ciuffoli V, Genzor P, Simone J, Haase AD, Pourquié O, Dell'Orso S, Sartorelli V. Transcriptomics, regulatory syntax, and enhancer identification in mesoderm-induced ESCs at single-cell resolution. Cell Rep 2022; 40:111219. [PMID: 35977485 DOI: 10.1016/j.celrep.2022.111219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 06/11/2022] [Accepted: 07/25/2022] [Indexed: 11/03/2022] Open
Abstract
Embryonic stem cells (ESCs) can adopt lineage-specific gene-expression programs by stepwise exposure to defined factors, resulting in the generation of functional cell types. Bulk and single-cell-based assays were employed to catalog gene expression, histone modifications, chromatin conformation, and accessibility transitions in ESC populations and individual cells acquiring a presomitic mesoderm fate and undergoing further specification toward myogenic and neurogenic lineages. These assays identified cis-regulatory regions and transcription factors presiding over gene-expression programs occurring at defined ESC transitions and revealed the presence of heterogeneous cell populations within discrete ESC developmental stages. The datasets were employed to identify previously unappreciated genomic elements directing the initial activation of Pax7 and myogenic and neurogenic gene-expression programs. This study provides a resource for the discovery of genomic and transcriptional features of pluripotent, mesoderm-induced ESCs and ESC-derived cell lineages.
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Affiliation(s)
- Mamduh Khateb
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), NIH, Bethesda, MD, USA
| | - Jelena Perovanovic
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), NIH, Bethesda, MD, USA
| | - Kyung Dae Ko
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), NIH, Bethesda, MD, USA
| | - Kan Jiang
- Biodata Mining and Discovery Section, NIAMS, NIH, Bethesda, MD, USA
| | - Xuesong Feng
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), NIH, Bethesda, MD, USA
| | - Natalia Acevedo-Luna
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), NIH, Bethesda, MD, USA
| | - Jérome Chal
- Department of Genetics, Harvard Medical School, Boston, MA, USA; Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA; Harvard Stem Cell Institute, Boston, MA, USA
| | - Veronica Ciuffoli
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), NIH, Bethesda, MD, USA
| | - Pavol Genzor
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD, USA
| | - James Simone
- FlowCytometry Section, NIAMS, NIH, Bethesda, MD, USA
| | - Astrid D Haase
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD, USA
| | - Olivier Pourquié
- Department of Genetics, Harvard Medical School, Boston, MA, USA; Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA; Harvard Stem Cell Institute, Boston, MA, USA
| | | | - Vittorio Sartorelli
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), NIH, Bethesda, MD, USA.
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Ornitz DM, Itoh N. New developments in the biology of fibroblast growth factors. WIREs Mech Dis 2022; 14:e1549. [PMID: 35142107 PMCID: PMC10115509 DOI: 10.1002/wsbm.1549] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 11/08/2021] [Accepted: 11/09/2021] [Indexed: 01/28/2023]
Abstract
The fibroblast growth factor (FGF) family is composed of 18 secreted signaling proteins consisting of canonical FGFs and endocrine FGFs that activate four receptor tyrosine kinases (FGFRs 1-4) and four intracellular proteins (intracellular FGFs or iFGFs) that primarily function to regulate the activity of voltage-gated sodium channels and other molecules. The canonical FGFs, endocrine FGFs, and iFGFs have been reviewed extensively by us and others. In this review, we briefly summarize past reviews and then focus on new developments in the FGF field since our last review in 2015. Some of the highlights in the past 6 years include the use of optogenetic tools, viral vectors, and inducible transgenes to experimentally modulate FGF signaling, the clinical use of small molecule FGFR inhibitors, an expanded understanding of endocrine FGF signaling, functions for FGF signaling in stem cell pluripotency and differentiation, roles for FGF signaling in tissue homeostasis and regeneration, a continuing elaboration of mechanisms of FGF signaling in development, and an expanding appreciation of roles for FGF signaling in neuropsychiatric diseases. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology Congenital Diseases > Stem Cells and Development Cancer > Stem Cells and Development.
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Affiliation(s)
- David M Ornitz
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Nobuyuki Itoh
- Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto, Japan
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Singh AP, Luo H, Matur M, Eshelman MA, Hamamoto K, Sharma A, Lesperance J, Huang S. A coordinated function of lncRNA HOTTIP and miRNA-196b underpinning leukemogenesis by targeting FAS signaling. Oncogene 2022; 41:718-731. [PMID: 34845377 PMCID: PMC8810734 DOI: 10.1038/s41388-021-02127-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 11/07/2021] [Accepted: 11/18/2021] [Indexed: 01/23/2023]
Abstract
MicroRNAs (miRNAs) may modulate more than 60% of human coding genes and act as negative regulators, whereas long noncoding RNAs (lncRNAs) regulate gene expression on multiple levels by interacting with chromatin, functional proteins, and RNAs such as mRNAs and microRNAs. However, the crosstalk between HOTTIP lncRNA and miRNAs in leukemogenesis remains elusive. Using combined integrated analyses of global miRNA expression profiling and state-of-the-art genomic analyses of chromatin such as ChIRP-seq (HOTTIP binding in genomewide), ChIP-seq, and ATAC-seq, we found that some miRNA genes are directly controlled by HOTTIP. Specifically, the HOX cluster miRNAs (miR-196a, miR-196b, miR-10a, and miR-10b), located cis and trans, were most dramatically regulated and significantly decreased in HOTTIP-/- AML cells. HOTTIP bound to the miR-196b promoter and HOTTIP deletion reduced chromatin accessibility and enrichment of active histone modifications at HOX cluster-associated miRNAs in AML cells, whereas reactivation of HOTTIP restored miR gene expression and chromatin accessibility in the CTCF-boundary-attenuated AML cells. Inactivation of HOTTIP or miR-196b promotes apoptosis by altering the chromatin signature at the FAS promoter and increasing FAS expression. Transplantation of miR-196b knockdown MOLM13 cells in NSG mice increased overall survival of mice compared to wild-type cells transplanted into mice. Thus, HOTTIP remodels the chromatin architecture around miRNAs to promote their transcription and consequently represses tumor suppressors and promotes leukemogenesis.
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Affiliation(s)
- Ajeet P Singh
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
- Thoracic Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Huacheng Luo
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
- Penn State Cancer Institute, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
| | - Meghana Matur
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Melanie A Eshelman
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Karina Hamamoto
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Arati Sharma
- Penn State Cancer Institute, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
- Division of Hematology and Oncology, Department of Medicine, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Julia Lesperance
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Suming Huang
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
- Penn State Cancer Institute, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
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Sasidharan V, Sánchez Alvarado A. The Diverse Manifestations of Regeneration and Why We Need to Study Them. Cold Spring Harb Perspect Biol 2021; 14:a040931. [PMID: 34750171 PMCID: PMC9438785 DOI: 10.1101/cshperspect.a040931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
For hundreds of years, the question of why some organisms can regenerate missing body parts while others cannot has remained poorly understood. This has been due in great part to the inability to genetically, molecularly, and cellularly dissect this problem for most of the history of the field. It has only been in the past 20-30 years that important mechanistic advances have been made in methodologies that introduce loss and gain of gene function in animals that can regenerate. However, we still have a very incomplete understanding of how broadly regenerative abilities may be dispersed across species and whether or not such properties share a common evolutionary origin, which may have emerged independently or both. Understanding regeneration, therefore, will require rigorously practiced fundamental, curiosity-driven, discovery research. Expanding the number of research organisms used to study regeneration allows us to uncover aspects of this problem we may not yet know exist and simultaneously increases our chances of solving this long-standing problem of biology.
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10
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Hong Q, Li XD, Xie P, Du SX. All-trans-retinoic acid suppresses rat embryo hindlimb bud mesenchymal chondrogenesis by modulating HoxD9 expression. Bioengineered 2021; 12:3900-3911. [PMID: 34288810 PMCID: PMC8806522 DOI: 10.1080/21655979.2021.1940613] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In vertebrates, 5ʹ-Hoxd genes (Hoxd9), which are expressed in the hindlimb bud mesenchyme, participate in limb growth and patterning in early embryonic development. In the present study, We investigated the mechanisms by which ATRA regulates cultured E12.5 rat embryo hindlimb bud mesenchymal cells (rEHBMCs). Following exposure to ATRA over 24 h, mRNA and protein expression levels of HoxD9 were evaluated by reverse transcription-polymerase chain reaction (RT-PCR), quantitative real-time PCR (qPCR), and western blotting. Flow cytometry was used to detect apoptosis. ATRA inhibited the condensation and proliferation, and promoted the apoptosis rate of the rEHBMCs in a dose-dependent manner. Sox9 and Col2a1 in rEHBMCs were downregulated by ATRA in a dose-dependent manner at both mRNA and protein levels. Similarly, HoxD9 was downregulated by ATRA in a dose-dependent manner, in parallel with the cartilage-specific molecules Sox9 and Col2a1. Both qPCR and western blotting showed that both Shh and Gli3 were downregulated. Overexpression of HoxD9 reversed the effects of ATRA. These results demonstrate that ATRA suppresses chondrogenesis in rEHBMCs by inhibiting the expression of HoxD9 and its downstream protein targets, including Sox9 and Col2a1. This effect may also be correlated with inhibition of the Shh-Gli3 signaling pathway.
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Affiliation(s)
- Quan Hong
- Department of Orthopedics, Jieyang People's Hospital (Jieyang Affiliated Hospital, Sun Yat-sen University), Jieyang, Guangdong, China
| | - Xue-Dong Li
- Department of Orthopedics, Shenzhen Luohu Hospital Group Luohu People's Hospital (The Third Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong, China
| | - Peng Xie
- Department of Orthopedics, Shenzhen Luohu Hospital Group Luohu People's Hospital (The Third Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong, China
| | - Shi-Xin Du
- Department of Orthopedics, Shenzhen Luohu Hospital Group Luohu People's Hospital (The Third Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong, China
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Lorda-Diez CI, Duarte-Olivenza C, Hurle JM, Montero JA. Transforming growth factor beta signaling: The master sculptor of fingers. Dev Dyn 2021; 251:125-136. [PMID: 33871876 DOI: 10.1002/dvdy.349] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 04/09/2021] [Accepted: 04/15/2021] [Indexed: 12/23/2022] Open
Abstract
Transforming growth factor beta (TGFβ) constitutes a large and evolutionarily conserved superfamily of secreted factors that play essential roles in embryonic development, cancer, tissue regeneration, and human degenerative pathology. Studies of this signaling cascade in the regulation of cellular and tissue changes in the three-dimensional context of a developing embryo have notably advanced in the understanding of the action mechanism of these growth factors. In this review, we address the role of TGFβ signaling in the developing limb, focusing on its essential function in the morphogenesis of the autopod. As we discuss in this work, modern mouse genetic experiments together with more classical embryological approaches in chick embryos, provided very valuable information concerning the role of TGFβ and Activin family members in the morphogenesis of the digits of tetrapods, including the formation of phalanxes, digital tendons, and interphalangeal joints. We emphasize the importance of the Activin and TGFβ proteins as digit inducing factors and their critical interaction with the BMP signaling to sculpt the hand and foot morphology.
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Affiliation(s)
- Carlos I Lorda-Diez
- Departamento de Anatomía y Biología Celular and IDIVAL, Universidad de Cantabria, Santander, Spain
| | - Cristina Duarte-Olivenza
- Departamento de Anatomía y Biología Celular and IDIVAL, Universidad de Cantabria, Santander, Spain
| | - Juan M Hurle
- Departamento de Anatomía y Biología Celular and IDIVAL, Universidad de Cantabria, Santander, Spain
| | - Juan A Montero
- Departamento de Anatomía y Biología Celular and IDIVAL, Universidad de Cantabria, Santander, Spain
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Zhao X, Yang W, Li G, Dong H, Hou J, Cao Z, Guan D. Expression of Fibroblast Growth Factor 4 in a Rat Model of Polydactyly of the Thumb Induced by Cytarabine. Med Sci Monit 2020; 26:e926953. [PMID: 32788570 PMCID: PMC7446283 DOI: 10.12659/msm.926953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Accepted: 07/29/2020] [Indexed: 06/11/2023] Open
Abstract
BACKGROUND The aim of this study was to assess the expression and mechanisms of fibroblast growth factor 4 in polydactyly of the thumb induced by cytarabine. MATERIAL AND METHODS Rats were intraperitoneally injected with cytarabine at different gestation periods (12.5 days, 13.5 days, and 14.5 days) to establish a polydactyly of the thumb model. Then, the expression of FGF4 in polydactyly was studied by whole-mount in situ hybridization. We used hematoxylin & eosin stain and cartilage stain to investigate the development of the skeleton and tissues in the embryo. Pictures were taken to determine the general shape of the deformity, then X-rays were taken to detect bone distortion of the rats born with a congenital malformation. RESULTS In the experimental group (11.5 days, 12.5 days, 13.5 days, and 14.5 days), whole-mount in situ hybridization showed that the FGF4 expression at the tip of the embryonic limb bud was significantly increased compared with the control group and FGF4 was distributed in a wider range and lasted longer than in the control group (P<0.01). HE staining and cartilage staining showed that there was an extra metacarpal bone and a phalanx in the rats with polydactyly of the thumb (P<0.01). Images of the deformed limbs showed polydactyly and syndactyly of the thumb in the rats. Further X-ray examination revealed 1 extra metacarpal bone and 1 extra phalanx. CONCLUSIONS Cytarabine can induce polydactyly and syndactyly of the thumb in rats. In this process, cytarabine can induce the expression of FGF4 on the tip of the embryonic limb bud, which further leads to abnormal development of the embryonic limb bud and eventually causes a congenital deformity.
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Feneck E, Logan M. The Role of Retinoic Acid in Establishing the Early Limb Bud. Biomolecules 2020; 10:biom10020312. [PMID: 32079177 PMCID: PMC7072211 DOI: 10.3390/biom10020312] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/12/2020] [Accepted: 02/13/2020] [Indexed: 01/09/2023] Open
Abstract
Retinoic acid (RA) was one of the first molecules in the modern era of experimental embryology to be shown capable of generating profound effects on limb development. In this review, we focus on the earliest events of limb development and specifically on the role of RA in establishing the domain of cells that will go on to form the limb itself. Although there is some consensus on the role of RA during the earliest stages of limb formation, some controversy remains on the mechanism of RA action and the requirement for RA signaling in forming the hindlimb buds.
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Du E, Lu C, Sheng F, Li C, Li H, Ding N, Chen Y, Zhang T, Yang K, Xu Y. Analysis of potential genes associated with primary cilia in bladder cancer. Cancer Manag Res 2018; 10:3047-3056. [PMID: 30214299 PMCID: PMC6124455 DOI: 10.2147/cmar.s175419] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Background Dysfunction of primary cilia (PC), which could influence cell cycle and modulate cilia-related signaling transduction, has been reported in several cancers. However, there is no evidence of their function in bladder cancer (BLCA). This study was performed to investigate the presence of PC in BLCA and to explore the potential molecular mechanisms underlying the PC in BLCA. Patients and methods The presence of PC was assessed in BLCA and adjacent non-cancerous tissues. The gene expression dataset GSE52519 was employed to obtain differentially expressed genes (DEGs) associated with PC. The mRNA expression of the DEGs were confirmed by Gene Expression Profiling Interactive Analysis. The DEGs properties and pathways were analyzed by Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. Genomatix software was used to predict putative transcription factor binding sites (TFBS) in the promoter region of DEGs, and the transcription factors were achieved according to the shared TFBS, which were supported by the ChIP-Sequence data. Results PC were found to be reduced in BLCA tissue samples in this study. Seven DEGs were observed to be associated with PC, and gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis indicated that these DEGs exhibited the properties and functions of PC, and that the Hedgehog signaling pathway probably participated in the pathogenesis and progression of BLCA. The mRNA expression of the seven DEGs in 404 BLCA and 28 normal tissue samples were analyzed, and five DEGs including CENPF, STIL, AURKA, STK39 and OSR1 were identified. Five TFBS including CREB, E2FF, EBOX, ETSF and HOXF in the promoter region of five DEGs were calculated and the transcription factors were obtained according to the shared TFBS. Conclusion PC were found to be reduced in BLCA, and the potential molecular mechanisms of PC in BLCA helped to provide novel diagnosis and therapeutic targets for BLCA.
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Affiliation(s)
- E Du
- Central Laboratory, Tianjin Institute of Urology, The Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China, ;
| | - Chao Lu
- Central Laboratory, Tianjin Institute of Urology, The Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China, ;
| | - Fei Sheng
- Central Laboratory, Tianjin Institute of Urology, The Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China, ;
| | - Changying Li
- Central Laboratory, Tianjin Institute of Urology, The Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China, ;
| | - Hong Li
- The Institute of Molecular Cardiology, Medical school, University of Louisville, Louisville, KY, USA
| | - Na Ding
- Central Laboratory, Tianjin Institute of Urology, The Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China, ;
| | - Yue Chen
- Central Laboratory, Tianjin Institute of Urology, The Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China, ;
| | - Ting Zhang
- Central Laboratory, Tianjin Institute of Urology, The Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China, ;
| | - Kuo Yang
- Central Laboratory, Tianjin Institute of Urology, The Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China, ;
| | - Yong Xu
- Central Laboratory, Tianjin Institute of Urology, The Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China, ;
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Zone of Polarizing Activity Regulatory Sequence Mutations/Duplications with Preaxial Polydactyly and Longitudinal Preaxial Ray Deficiency in the Phenotype: A Review of Human Cases, Animal Models, and Insights Regarding the Pathogenesis. BIOMED RESEARCH INTERNATIONAL 2018; 2018:1573871. [PMID: 29651423 PMCID: PMC5832050 DOI: 10.1155/2018/1573871] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/19/2017] [Accepted: 01/16/2018] [Indexed: 02/06/2023]
Abstract
Clinicians and scientists interested in developmental biology have viewed preaxial polydactyly (PPD) and longitudinal preaxial ray deficiency (LPAD) as two different entities. Point mutations and duplications in the zone of polarizing activity regulatory sequence (ZRS) are associated with anterior ectopic expression of Sonic Hedgehog (SHH) in the limb bud and usually result in a PPD phenotype. However, some of these mutations/duplications also have LPAD in the phenotype. This unusual PPD-LPAD association in ZRS mutations/duplications has not been specifically reviewed in the literature. The author reviews this unusual entity and gives insights regarding its pathogenesis.
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Lalonde RL, Akimenko MA. Effects of fin fold mesenchyme ablation on fin development in zebrafish. PLoS One 2018; 13:e0192500. [PMID: 29420592 PMCID: PMC5805328 DOI: 10.1371/journal.pone.0192500] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 01/24/2018] [Indexed: 11/19/2022] Open
Abstract
The evolution of the tetrapod limb involved an expansion and elaboration of the endoskeletal elements, while the fish fin rays were lost. Loss of fin-specific genes, and regulatory changes in key appendicular patterning genes have been identified as mechanisms of limb evolution, however their contributions to cellular organization and tissue differences between fins and limbs remains poorly understood. During early larval fin development, hoxa13a/hoxd13a-expressing fin fold mesenchyme migrate through the median and pectoral fin along actinotrichia fibrils, non-calcified skeletal elements crucial for supporting the fin fold. Fin fold mesenchyme migration defects have previously been proposed as a mechanism of fin dermal bone loss during tetrapod evolution as it has been shown they contribute directly to the fin ray osteoblast population. Using the nitroreductase/metronidazole system, we genetically ablated a subset of hoxa13a/hoxd13a-expressing fin fold mesenchyme to assess its contributions to fin development. Following the ablation of fin fold mesenchyme in larvae, the actinotrichia are unable to remain rigid and the median and pectoral fin folds collapse, resulting in a reduced fin fold size. The remaining cells following ablation are unable to migrate and show decreased actinodin1 mesenchymal reporter activity. Actinodin proteins are crucial structural component of the actinotrichia. Additionally, we show a decrease in hoxa13a, hoxd13a, fgf10a and altered shha, and ptch2 expression during larval fin development. A continuous treatment of metronidazole leads to fin ray defects at 30dpf. Fewer rays are present compared to stage-matched control larvae, and these rays are shorter and less defined. These results suggest the targeted hoxa13a/hoxd13a-expressing mesenchyme contribute to their own successful migration through their contributions to actinotrichia. Furthermore, due to their fate as fin ray osteoblasts, we propose their initial ablation, and subsequent disorganization produces truncated fin dermal bone elements during late larval stages.
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Affiliation(s)
- Robert L. Lalonde
- Department of Biology, University of Ottawa, 20 Marie-Curie, Ottawa, Ontario, Canada
| | - Marie-Andrée Akimenko
- Department of Biology, University of Ottawa, 20 Marie-Curie, Ottawa, Ontario, Canada
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Abstract
Collinear regulation of Hox genes in space and time has been an outstanding question ever since the initial work of Ed Lewis in 1978. Here we discuss recent advances in our understanding of this phenomenon in relation to novel concepts associated with large-scale regulation and chromatin structure during the development of both axial and limb patterns. We further discuss how this sequential transcriptional activation marks embryonic stem cell-like axial progenitors in mammals and, consequently, how a temporal genetic system is further translated into spatial coordinates via the fate of these progenitors. In this context, we argue the benefit and necessity of implementing this unique mechanism as well as the difficulty in evolving an alternative strategy to deliver this critical positional information.
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Affiliation(s)
- Jacqueline Deschamps
- Hubrecht Institute, University Medical Center Utrecht, 3584 CT Utrecht, the Netherlands
| | - Denis Duboule
- School of Life Sciences, Ecole Polytechnique Fédérale, Lausanne, 1015 Lausanne, Switzerland.,Department of Genetics and Evolution, University of Geneva, 1211 Geneva 4, Switzerland
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Paço A, Freitas R. Hox D genes and the fin-to-limb
transition: Insights from fish studies. Genesis 2017; 56. [DOI: 10.1002/dvg.23069] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 08/14/2017] [Accepted: 09/08/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Ana Paço
- IBMC - Instituto de Biologia Celular e Molecular; Porto Portugal
- I3S - Instituto de Investigação e Inovação em Saúde; Porto Portugal
- Universidade do Porto; Porto Portugal
| | - Renata Freitas
- IBMC - Instituto de Biologia Celular e Molecular; Porto Portugal
- I3S - Instituto de Investigação e Inovação em Saúde; Porto Portugal
- Universidade do Porto; Porto Portugal
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Abstract
Hox gene collinearity was discovered be Edward B. Lewis in 1978. It consists of the Hox1, Hox2, Hox3 ordering of the Hox genes in the chromosome from the telomeric to the centromeric side of the chromosome. Surprisingly, the spatial activation of the Hox genes in the ontogenetic units of the embryo follows the same ordering along the anterior-posterior embryonic axis. The chromosome microscale differs from the embryo macroscale by 3 to 4 orders of magnitude. The traditional biomolecular mechanisms are not adequate to comprise phenomena at so divergent spatial domains. A Biophysical Model of physical forces was proposed which can bridge the intermediate space and explain the results of genetic engineering experiments. Recent progress in constructing instruments and achieving high resolution imaging (e.g., 3D DNA FISH, STORM etc.) enable the assessment of the geometric structure of the chromatin during the different phases of Hox gene activation. It is found that the mouse HoxD gene cluster is elongated up to 5-6 times during Hox gene transcription. These unexpected findings agree with the BM predictions. It is now possible to measure several physical quantities inside the nucleus during Hox gene activation. New experiments are proposed to test further this model.
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