1
|
McDaniel C, Simsek MF, Chandel AS, Özbudak EM. Spatiotemporal control of pattern formation during somitogenesis. SCIENCE ADVANCES 2024; 10:eadk8937. [PMID: 38277458 PMCID: PMC10816718 DOI: 10.1126/sciadv.adk8937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 12/27/2023] [Indexed: 01/28/2024]
Abstract
Spatiotemporal patterns widely occur in biological, chemical, and physical systems. Particularly, embryonic development displays a diverse gamut of repetitive patterns established in many tissues and organs. Branching treelike structures in lungs, kidneys, livers, pancreases, and mammary glands as well as digits and bones in appendages, teeth, and palates are just a few examples. A fascinating instance of repetitive patterning is the sequential segmentation of the primary body axis, which is conserved in all vertebrates and many arthropods and annelids. In these species, the body axis elongates at the posterior end of the embryo containing an unsegmented tissue. Meanwhile, segments sequentially bud off from the anterior end of the unsegmented tissue, laying down an exquisite repetitive pattern and creating a segmented body plan. In vertebrates, the paraxial mesoderm is sequentially divided into somites. In this review, we will discuss the most prominent models, the most puzzling experimental data, and outstanding questions in vertebrate somite segmentation.
Collapse
Affiliation(s)
- Cassandra McDaniel
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
- Systems Biology and Physiology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - M. Fethullah Simsek
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Angad Singh Chandel
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
- Systems Biology and Physiology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Ertuğrul M. Özbudak
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| |
Collapse
|
2
|
Mulley JF. Regulation of posterior Hox genes by sex steroids explains vertebral variation in inbred mouse strains. J Anat 2022; 240:735-745. [PMID: 34747015 PMCID: PMC8930804 DOI: 10.1111/joa.13580] [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: 08/31/2021] [Revised: 10/08/2021] [Accepted: 10/21/2021] [Indexed: 11/29/2022] Open
Abstract
A series of elegant embryo transfer experiments in the 1950s demonstrated that the uterine environment could alter vertebral patterning in inbred mouse strains. In the intervening decades, attention has tended to focus on the technical achievements involved and neglected the underlying biological question: how can genetically homogenous individuals have a heterogenous number of vertebrae? Here I revisit these experiments and, with the benefit of knowledge of the molecular-level processes of vertebral patterning gained over the intervening decades, suggest a novel hypothesis for homeotic transformation of the last lumbar vertebra to the adjacent sacral type through regulation of Hox genes by sex steroids. Hox genes are involved in both axial patterning and development of male and female reproductive systems and have been shown to be sensitive to sex steroids in vitro and in vivo. Regulation of these genes by sex steroids and resulting alterations to vertebral patterning may hint at a deep evolutionary link between the ribless lumbar region of mammals and the switch from egg-laying to embryo implantation. An appreciation of the impact of sex steroids on Hox genes may explain some puzzling aspects of human disease, and highlights the spine as a neglected target for in utero exposure to endocrine disruptors.
Collapse
|
3
|
Paulissen E, Palmisano NJ, Waxman J, Martin BL. Somite morphogenesis is required for axial blood vessel formation during zebrafish embryogenesis. eLife 2022; 11:74821. [PMID: 35137687 PMCID: PMC8863375 DOI: 10.7554/elife.74821] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 02/07/2022] [Indexed: 11/13/2022] Open
Abstract
Angioblasts that form the major axial blood vessels of the dorsal aorta and cardinal vein migrate toward the embryonic midline from distant lateral positions. Little is known about what controls the precise timing of angioblast migration and their final destination at the midline. Using zebrafish, we found that midline angioblast migration requires neighboring tissue rearrangements generated by somite morphogenesis. The somitic shape changes cause the adjacent notochord to separate from the underlying endoderm, creating a ventral midline cavity that provides a physical space for the angioblasts to migrate into. The anterior to posterior progression of midline angioblast migration is facilitated by retinoic acid-induced anterior to posterior somite maturation and the subsequent progressive opening of the ventral midline cavity. Our work demonstrates a critical role for somite morphogenesis in organizing surrounding tissues to facilitate notochord positioning and angioblast migration, which is ultimately responsible for creating a functional cardiovascular system.
Collapse
Affiliation(s)
- Eric Paulissen
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, United States
| | - Nicholas J Palmisano
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, United States
| | - Joshua Waxman
- Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, United States
| | - Benjamin Louis Martin
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, United States
| |
Collapse
|
4
|
Kuyyamudi C, Menon SN, Sinha S. Morphogen-regulated contact-mediated signaling between cells can drive the transitions underlying body segmentation in vertebrates. Phys Biol 2021; 19. [PMID: 34670199 DOI: 10.1088/1478-3975/ac31a3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 10/20/2021] [Indexed: 11/12/2022]
Abstract
We propose a unified mechanism that reproduces the sequence of dynamical transitions observed during somitogenesis, the process of body segmentation during embryonic development, that is invariant across all vertebrate species. This is achieved by combining inter-cellular interactions mediated via receptor-ligand coupling with global spatial heterogeneity introduced through a morphogen gradient known to occur along the anteroposterior axis. Our model reproduces synchronized oscillations in the gene expression in cells at the anterior of the presomitic mesoderm as it grows by adding new cells at its posterior, followed by travelling waves and subsequent arrest of activity, with the eventual appearance of somite-like patterns. This framework integrates a boundary-organized pattern formation mechanism, which uses positional information provided by a morphogen gradient, with the coupling-mediated self-organized emergence of collective dynamics, to explain the processes that lead to segmentation.
Collapse
Affiliation(s)
- Chandrashekar Kuyyamudi
- The Institute of Mathematical Sciences, CIT Campus, Taramani, Chennai 600113, India.,Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India
| | - Shakti N Menon
- The Institute of Mathematical Sciences, CIT Campus, Taramani, Chennai 600113, India
| | - Sitabhra Sinha
- The Institute of Mathematical Sciences, CIT Campus, Taramani, Chennai 600113, India.,Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India
| |
Collapse
|
5
|
Newman SA, Bhat R, Glimm T. Spatial waves and temporal oscillations in vertebrate limb development. Biosystems 2021; 208:104502. [PMID: 34364929 DOI: 10.1016/j.biosystems.2021.104502] [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: 04/11/2021] [Revised: 08/03/2021] [Accepted: 08/03/2021] [Indexed: 10/20/2022]
Abstract
The mesenchymal tissue of the developing vertebrate limb bud is an excitable medium that sustains both spatial and temporal periodic phenomena. The first of these is the outcome of general Turing-type reaction-diffusion dynamics that generate spatial standing waves of cell condensations. These condensations are transformed into the nodules and rods of the cartilaginous, and eventually (in most species) the bony, endoskeleton. In the second, temporal periodicity results from intracellular regulatory dynamics that generate oscillations in the expression of one or more gene whose products modulate the spatial patterning system. Here we review experimental evidence from the chicken embryo, interpreted by a set of mathematical and computational models, that the spatial wave-forming system is based on two glycan-binding proteins, galectin-1A and galectin-8 in interaction with each other and the cells that produce them, and that the temporal oscillation occurs in the expression of the transcriptional coregulator Hes1. The multicellular synchronization of the Hes1 oscillation across the limb bud serves to coordinate the biochemical states of the mesenchymal cells globally, thereby refining and sharpening the spatial pattern. Significantly, the wave-forming reaction-diffusion-based mechanism itself, unlike most Turing-type systems, does not contain an oscillatory core, and may have evolved to this condition as it came to incorporate the cell-matrix adhesion module that enabled its pattern-forming capability.
Collapse
Affiliation(s)
- Stuart A Newman
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA.
| | - Ramray Bhat
- Department of Molecular Reproduction, Development and Genetics, Biological Sciences Division, Indian Institute of Science, Bangalore, 560012, India
| | - Tilmann Glimm
- Department of Mathematics, Western Washington University Bellingham, WA, 98229, USA
| |
Collapse
|
6
|
A mechanical model of early somite segmentation. iScience 2021; 24:102317. [PMID: 33889816 PMCID: PMC8050378 DOI: 10.1016/j.isci.2021.102317] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 01/15/2021] [Accepted: 03/12/2021] [Indexed: 11/21/2022] Open
Abstract
Somitogenesis is often described using the clock-and-wavefront (CW) model, which does not explain how molecular signaling rearranges the pre-somitic mesoderm (PSM) cells into somites. Our scanning electron microscopy analysis of chicken embryos reveals a caudally-progressing epithelialization front in the dorsal PSM that precedes somite formation. Signs of apical constriction and tissue segmentation appear in this layer 3-4 somite lengths caudal to the last-formed somite. We propose a mechanical instability model in which a steady increase of apical contractility leads to periodic failure of adhesion junctions within the dorsal PSM and positions the future inter-somite boundaries. This model produces spatially periodic segments whose size depends on the speed of the activation front of contraction (F), and the buildup rate of contractility (Λ). The Λ/F ratio determines whether this mechanism produces spatially and temporally regular or irregular segments, and whether segment size increases with the front speed. Dorsal pre-somitic mesoderm of chicken embryos epithelializes before somite formation Dorsal epithelium shows signs of apical constriction and early segmentation A mechanical instability model can reproduce sequential segmentation A single ratio describes spatial and temporal patterns of segmentation
Collapse
|
7
|
Ravikanth R, Majumdar P. Embryological considerations and evaluation of congenital anomalies of craniovertebral junction: A single-center experience. Tzu Chi Med J 2020; 33:175-180. [PMID: 33912416 PMCID: PMC8059470 DOI: 10.4103/tcmj.tcmj_62_20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/08/2020] [Accepted: 06/26/2020] [Indexed: 11/04/2022] Open
Abstract
Objectives Craniovertebral junction (CVJ) abnormalities constitute a group of treatable neurological disorders, especially in the Indian subcontinent. Thus, it is essential that clinicians should be able to make a precise diagnosis of abnormalities and rule out important mimickers on multidetector computed tomography (MDCT) as this information ultimately helps determine the management, prognosis, and quality of life of patients. CVJ is the most complex part of the cervical region. Congenital malformations of this region can cause serious neurological deficit and require a surgical intervention. The present study was undertaken to know the embryological basis of the CVJ and to identify commonly observed congenital CVJ abnormalities, their frequency, and mode of presentation. Materials and Methods Diagnosed cases of CVJ anomalies on dynamic MDCT head were reviewed at a tertiary care center between January 2014 to December 2019. Type of anomaly, clinical presentation, and associated malformations were recorded. Different types of variations were expressed in terms of percentage. Results Congenital anomalies were seen in 42 cases. Fifteen types of anomalies were detected. Anomalies were either singly or in combination. The CVJ anomalies were more common in young adults (28%), almost equal in both sexes. The most common anomaly was basilar invagination (52.3%), followed by atlanto-occipital assimilation (33.3%), and Arnold-Chiari malformation is the most common soft tissue anomaly. In fourteen cases, additional anomalies of other vertebrae were present. The most common symptoms were weakness of extremities, neck pain, paresthesia, torticollis, and gait disturbances. About 28 patients got improved, 8 patients had residual deficit as that of preoperative status, and 4 patients got deteriorated after surgery, at 1-month follow-up. About 34 patients had improved, 5 remained static, and 3 patients got worsened at the end of 3-month follow-up. About 37 patients had improved, 4 patients remained static, and 2 patients got deteriorated at 6 months of follow-up. The patients with increased atlantodens interval 3-5 mm showed 77% improvement after surgery. Conclusion Congenital CVJ anomalies, though rare, are fatal. CVJ abnormalities constitute an important group of treatable neurological disorders with diagnostic dilemma. The atlantodental interval is the most important preoperative prognostic marker. Dynamic CT imaging can provide additional useful information to the diagnosis of CVJ instability. To prevent long-term neurological problems, early diagnosis and treatment of congenital bony CVJ anomalies is important.
Collapse
Affiliation(s)
- Reddy Ravikanth
- Department of Radiology, St. John's Hospital, Kattappana, Kerala, India
| | - Pooja Majumdar
- Department of Medicine, INHS Kalyani, Visakhapatnam, Andhra Pradesh, India
| |
Collapse
|
8
|
Bhavna R. Segmentation clock dynamics is strongly synchronized in the forming somite. Dev Biol 2020; 460:55-69. [PMID: 30926261 DOI: 10.1016/j.ydbio.2019.03.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 03/13/2019] [Accepted: 03/13/2019] [Indexed: 10/27/2022]
Abstract
During vertebrate somitogenesis an inherent segmentation clock coordinates the spatiotemporal signaling to generate segmented structures that pattern the body axis. Using our experimental and quantitative approach, we study the cell movements and the genetic oscillations of her1 expression level at single-cell resolution simultaneously and scale up to the entire pre-somitic mesoderm (PSM) tissue. From the experimentally determined phases of PSM cellular oscillators, we deduced an in vivo frequency profile gradient along the anterior-posterior PSM axis and inferred precise mathematical relations between spatial cell-level period and tissue-level somitogenesis period. We also confirmed a gradient in the relative velocities of cellular oscillators along the axis. The phase order parameter within an ensemble of oscillators revealed the degree of synchronization in the tailbud and the posterior PSM being only partial, whereas synchronization can be almost complete in the presumptive somite region but with temporal oscillations. Collectively, the degree of synchronization itself, possibly regulated by cell movement and the synchronized temporal phase of the transiently expressed clock protein Her1, can be an additional control mechanism for making precise somite boundaries.
Collapse
Affiliation(s)
- Rajasekaran Bhavna
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307, Dresden, Germany; Max Planck Institute for the Physics of Complex Systems, 01187, Dresden, Germany; Tata Institute of Fundamental Research, 400005, Mumbai, India.
| |
Collapse
|
9
|
El-Magd MA, Elsayed SA, El-Shetry ES, Abdelfattah-Hassan A, Saleh AA, Allen S, McGonnell I, Patel K. The role of chick Ebf genes in the mediolateral patterning of the somites. Genesis 2019; 57:e23339. [PMID: 31724301 DOI: 10.1002/dvg.23339] [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: 06/01/2019] [Revised: 09/05/2019] [Accepted: 09/06/2019] [Indexed: 11/06/2022]
Abstract
This study was conducted to check whether the three chick Early B-cell Factor (Ebf) genes, particularly cEbf1, would be targets for Shh and Bmp signals during somites mediolateral (ML) patterning. Tissue manipulations and gain and loss of function experiments for Shh and Bmp4 were performed and the results revealed that cEbf1 expression was initiated in the cranial presomitic mesoderm by low dose of Bmp4 from the lateral mesoderm and maintained in the ventromedial part of the epithelial somite and the medial sclerotome by Shh from the notochord; while cEbf2/3 expression was induced and maintained by Bmp4 and inhibited by high dose of Shh. To determine whether Ebf1 plays a role in somite patterning, transfection of a dominant-negative construct was carried out; this showed suppression of cPax1 expression in the medial sclerotome and upregulation and medial expansion of cEbf3 and cPax3 expression in sclerotome and dermomyotome, respectively, suggesting that Ebf1 is important for ML patterning. Thus, it is possible that low doses of Bmp4 set up Ebf1 expression which, together with Shh from the notochord, leads to establishment of the medial sclerotome and suppression of lateral identities. These data also conclude that Bmp4 is required in both the medial and lateral domain of the somitic mesoderm to keep the ML identity of the sclerotome through maintenance of cEbf gene expression. These striking findings are novel and give a new insight on the role of Bmp4 on mediolateral patterning of somites.
Collapse
Affiliation(s)
- Mohammed A El-Magd
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Kafrelsheikh University, Kfrelsheikh, Egypt
| | - Shafika A Elsayed
- Department of Histology and Cytology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
| | - Eman S El-Shetry
- Department of Human Anatomy and Embryology, Faculty of Medicine, Zagazig University, Zagazig, Egypt
| | - Ahmed Abdelfattah-Hassan
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
| | - Ayman A Saleh
- Department of Animal Wealth Development, Genetics and Genetic Engineering, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
| | - Steve Allen
- Department of Veterinary Basic Sciences, Royal Veterinary College, London, United Kingdom
| | - Imelda McGonnell
- Department of Veterinary Basic Sciences, Royal Veterinary College, London, United Kingdom
| | - Ketan Patel
- School of Biological Sciences, University of Reading, Reading, United Kingdom
| |
Collapse
|
10
|
Newman SA. Inherency and homomorphy in the evolution of development. Curr Opin Genet Dev 2019; 57:1-8. [DOI: 10.1016/j.gde.2019.05.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 05/15/2019] [Accepted: 05/24/2019] [Indexed: 02/06/2023]
|
11
|
Braunreiter KM, Cole SE. A tale of two clocks: phosphorylation of NICD by CDKs links cell cycle and segmentation clock. EMBO Rep 2019; 20:e48247. [PMID: 31267704 PMCID: PMC6607009 DOI: 10.15252/embr.201948247] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The Notch signaling pathway is tightly controlled via post-transcriptional regulatory mechanisms that promote or terminate pathway activity. In this issue, Carrieri et al [1] show that phosphorylation of the Notch intracellular domain (NICD) by cyclin-dependent kinases (CDKs) suppresses Notch activity by promoting NICD turnover. These findings link Notch pathway activity to the cell cycle, and the authors propose connections between this regulation and the segmentation clock that times embryonic somitogenesis.
Collapse
Affiliation(s)
| | - Susan E Cole
- Department of Molecular GeneticsThe Ohio State UniversityColumbusOHUSA
| |
Collapse
|
12
|
Eich C, Arlt J, Vink CS, Solaimani Kartalaei P, Kaimakis P, Mariani SA, van der Linden R, van Cappellen WA, Dzierzak E. In vivo single cell analysis reveals Gata2 dynamics in cells transitioning to hematopoietic fate. J Exp Med 2017; 215:233-248. [PMID: 29217535 PMCID: PMC5748852 DOI: 10.1084/jem.20170807] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 09/12/2017] [Accepted: 10/31/2017] [Indexed: 01/07/2023] Open
Abstract
Eich et al. reveal the dynamic expression of the Gata2 transcription factor in single aortic cells transitioning to hematopoietic fate by vital imaging of Gata2Venus mouse embryos. Pulsatile expression level changes highlight an unstable genetic state during hematopoietic cell generation. Cell fate is established through coordinated gene expression programs in individual cells. Regulatory networks that include the Gata2 transcription factor play central roles in hematopoietic fate establishment. Although Gata2 is essential to the embryonic development and function of hematopoietic stem cells that form the adult hierarchy, little is known about the in vivo expression dynamics of Gata2 in single cells. Here, we examine Gata2 expression in single aortic cells as they establish hematopoietic fate in Gata2Venus mouse embryos. Time-lapse imaging reveals rapid pulsatile level changes in Gata2 reporter expression in cells undergoing endothelial-to-hematopoietic transition. Moreover, Gata2 reporter pulsatile expression is dramatically altered in Gata2+/− aortic cells, which undergo fewer transitions and are reduced in hematopoietic potential. Our novel finding of dynamic pulsatile expression of Gata2 suggests a highly unstable genetic state in single cells concomitant with their transition to hematopoietic fate. This reinforces the notion that threshold levels of Gata2 influence fate establishment and has implications for transcription factor–related hematologic dysfunctions.
Collapse
Affiliation(s)
- Christina Eich
- Department of Cell Biology, Erasmus Stem Cell Institute, Erasmus Medical Center, Rotterdam, Netherlands
| | - Jochen Arlt
- School of Physics and Astronomy, The University of Edinburgh, Edinburgh, Scotland, UK
| | - Chris S Vink
- Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, Scotland, UK
| | | | - Polynikis Kaimakis
- Department of Cell Biology, Erasmus Stem Cell Institute, Erasmus Medical Center, Rotterdam, Netherlands
| | - Samanta A Mariani
- Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, Scotland, UK
| | - Reinier van der Linden
- Department of Cell Biology, Erasmus Stem Cell Institute, Erasmus Medical Center, Rotterdam, Netherlands
| | - Wiggert A van Cappellen
- Department of Pathology, Erasmus Optical Imaging Centre, Erasmus Medical Center, Rotterdam, Netherlands
| | - Elaine Dzierzak
- Department of Cell Biology, Erasmus Stem Cell Institute, Erasmus Medical Center, Rotterdam, Netherlands .,Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, Scotland, UK
| |
Collapse
|
13
|
Chun C, Wu Y, Lee SH, Williamson EA, Reinert BL, Jaiswal AS, Nickoloff JA, Hromas RA. The homologous recombination component EEPD1 is required for genome stability in response to developmental stress of vertebrate embryogenesis. Cell Cycle 2017; 15:957-62. [PMID: 26900729 PMCID: PMC4889227 DOI: 10.1080/15384101.2016.1151585] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Stressed replication forks can be conservatively repaired and restarted using homologous recombination (HR), initiated by nuclease cleavage of branched structures at stalled forks. We previously reported that the 5' nuclease EEPD1 is recruited to stressed replication forks, where it plays critical early roles in HR initiation by promoting fork cleavage and end resection. HR repair of stressed replication forks prevents their repair by non-homologous end-joining (NHEJ), which would cause genome instability. Rapid cell division during vertebrate embryonic development generates enormous pressure to maintain replication speed and accuracy. To determine the role of EEPD1 in maintaining replication fork integrity and genome stability during rapid cell division in embryonic development, we assessed the role of EEPD1 during zebrafish embryogenesis. We show here that when EEPD1 is depleted, zebrafish embryos fail to develop normally and have a marked increase in death rate. Zebrafish embryos depleted of EEPD1 are far more sensitive to replication stress caused by nucleotide depletion. We hypothesized that the HR defect with EEPD1 depletion would shift repair of stressed replication forks to unopposed NHEJ, causing chromosome abnormalities. Consistent with this, EEPD1 depletion results in nuclear defects including anaphase bridges and micronuclei in stressed zebrafish embryos, similar to BRCA1 deficiency. These results demonstrate that the newly characterized HR protein EEPD1 maintains genome stability during embryonic replication stress. These data also imply that the rapid cell cycle transit seen during embryonic development produces replication stress that requires HR to resolve.
Collapse
Affiliation(s)
- Changzoon Chun
- a Division of Hematology/Oncology , Department of Medicine, University of Florida Health , Gainesville , FL , USA
| | - Yuehan Wu
- a Division of Hematology/Oncology , Department of Medicine, University of Florida Health , Gainesville , FL , USA
| | - Suk-Hee Lee
- b Department of Biochemistry and Molecular Biology , Indiana University School of Medicine , Indianapolis , IN , USA
| | - Elizabeth A Williamson
- a Division of Hematology/Oncology , Department of Medicine, University of Florida Health , Gainesville , FL , USA
| | - Brian L Reinert
- a Division of Hematology/Oncology , Department of Medicine, University of Florida Health , Gainesville , FL , USA
| | - Aruna Shanker Jaiswal
- a Division of Hematology/Oncology , Department of Medicine, University of Florida Health , Gainesville , FL , USA
| | - Jac A Nickoloff
- c Department of Environmental and Radiological Health Sciences , Colorado State University , Fort Collins , CO , USA
| | - Robert A Hromas
- a Division of Hematology/Oncology , Department of Medicine, University of Florida Health , Gainesville , FL , USA
| |
Collapse
|
14
|
Kalcheim C. Epithelial-Mesenchymal Transitions during Neural Crest and Somite Development. J Clin Med 2015; 5:jcm5010001. [PMID: 26712793 PMCID: PMC4730126 DOI: 10.3390/jcm5010001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 12/09/2015] [Accepted: 12/14/2015] [Indexed: 01/14/2023] Open
Abstract
Epithelial-to-mesenchymal transition (EMT) is a central process during embryonic development that affects selected progenitor cells of all three germ layers. In addition to driving the onset of cellular migrations and subsequent tissue morphogenesis, the dynamic conversions of epithelium into mesenchyme and vice-versa are intimately associated with the segregation of homogeneous precursors into distinct fates. The neural crest and somites, progenitors of the peripheral nervous system and of skeletal tissues, respectively, beautifully illustrate the significance of EMT to the above processes. Ongoing studies progressively elucidate the gene networks underlying EMT in each system, highlighting the similarities and differences between them. Knowledge of the mechanistic logic of this normal ontogenetic process should provide important insights to the understanding of pathological conditions such as cancer metastasis, which shares some common molecular themes.
Collapse
Affiliation(s)
- Chaya Kalcheim
- Edmond and Lili Safra Center for Brain Sciences (ELSC), Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC), Hebrew University of Jerusalem-Hadassah Medical School, P.O. Box 12272, Jerusalem 9112102, Israel.
| |
Collapse
|
15
|
Abstract
Anterior-posterior (A-P) patterning of the vertebrate main body axis regulated by timing. Anterior structures are specified early, posterior late. (1) Timing involves timed decision points as emphasised by the Wnt studies of Sokol and colleagues. It also involves complex timers, where large parts of the axis are patterned sequentially by a common upstream mechanism (articles by Durston et al., Mullins et al., Oates et al.,). (2) A gastrula BMP-anti BMP dependent time-space translation (TST) mechanism was demonstrated for the trunk section of the axis (Durston). (3) Thisses' studies emphasise the importance of BMP-anti BMP and the organiser inducing factor nodal for A-P patterning. (4) Meinhardt's interesting studies on the organiser and A-P patterning are reviewed in relation to TST. (5) Mullins' investigations show that anti-BMP dependent TST starts earlier (at the blastula stage) and extends further anteriorly (to the anterior head). Sive's studies imply it may extend further still to the "extreme anterior domain" (EAD). (6) The somitogenesis timer (clock) is presented. Stern's and Oates' findings are discussed. (7) Relations between somitogenesis and axial TST are discussed. (8) Relations of classical axial patterning pathways to TST decision points and somitogenesis are inventarised. In conclusion, all of these findings point to an integral BMP-anti BMP dependent A-P TST mechanism, running from cement gland in the EAD, Six3 and the anterior tip of the forebrain at blastula stages to Hox13 and the tip of the tail by the mid neurula stage. TST acts via sequential timed transitions between ventral (unstable, timed) and dorsal (stabilised) states. In the trunk-tail, the timer is thought to be Hox temporal collinearity and TST depends on Hox function. In the head, TST is under investigation. The somitogenesis clock is upstream of the TST timer, providing precision in the posterior part of the axis at least. Classical A-P signalling pathways: retinoids, FGFs and Wnts, change behaviour at functional decision points on the axis.
Collapse
|