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Griffin C, Saint-Jeannet JP. In vitro modeling of cranial placode differentiation: Recent advances, challenges, and perspectives. Dev Biol 2024; 506:20-30. [PMID: 38052294 PMCID: PMC10843546 DOI: 10.1016/j.ydbio.2023.11.009] [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: 05/26/2023] [Revised: 11/27/2023] [Accepted: 11/29/2023] [Indexed: 12/07/2023]
Abstract
Cranial placodes are transient ectodermal thickenings that contribute to a diverse array of organs in the vertebrate head. They develop from a common territory, the pre-placodal region that over time segregates along the antero-posterior axis into individual placodal domains: the adenohypophyseal, olfactory, lens, trigeminal, otic, and epibranchial placodes. These placodes terminally differentiate into the anterior pituitary, the lens, and contribute to sensory organs including the olfactory epithelium, and inner ear, as well as several cranial ganglia. To study cranial placodes and their derivatives and generate cells for therapeutic purposes, several groups have turned to in vitro derivation of placodal cells from human embryonic stem cells (hESCs) or induced pluripotent stem cells (hiPSCs). In this review, we summarize the signaling cues and mechanisms involved in cranial placode induction, specification, and differentiation in vivo, and discuss how this knowledge has informed protocols to derive cranial placodes in vitro. We also discuss the benefits and limitations of these protocols, and the potential of in vitro cranial placode modeling in regenerative medicine to treat cranial placode-related pathologies.
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Affiliation(s)
- Casey Griffin
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, 10010, USA
| | - Jean-Pierre Saint-Jeannet
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, 10010, USA.
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2
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Marchak A, Neilson KM, Majumdar HD, Yamauchi K, Klein SL, Moody SA. The sulfotransferase XB5850668.L is required to apportion embryonic ectodermal domains. Dev Dyn 2023; 252:1407-1427. [PMID: 37597164 PMCID: PMC10842325 DOI: 10.1002/dvdy.648] [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: 04/04/2023] [Revised: 06/08/2023] [Accepted: 07/26/2023] [Indexed: 08/21/2023] Open
Abstract
BACKGROUND Members of the sulfotransferase superfamily (SULT) influence the activity of a wide range of hormones, neurotransmitters, metabolites and xenobiotics. However, their roles in developmental processes are not well characterized even though they are expressed during embryogenesis. We previously found in a microarray screen that Six1 up-regulates LOC100037047, which encodes XB5850668.L, an uncharacterized sulfotransferase. RESULTS Since Six1 is required for patterning the embryonic ectoderm into its neural plate, neural crest, preplacodal and epidermal domains, we used loss- and gain-of function assays to characterize the role of XB5850668.L during this process. Knockdown of endogenous XB5850668.L resulted in the reduction of epidermal, neural crest, cranial placode and otic vesicle gene expression domains, concomitant with neural plate expansion. Increased levels had minimal effects, but infrequently expanded neural plate and neural crest gene domains, and infrequently reduced cranial placode and otic vesicle gene domains. Mutation of two key amino acids in the sulfotransferase catalytic domain required for PAPS binding and enzymatic activity tended to reduce the effects of overexpressing the wild-type protein. CONCLUSIONS Our analyses indicates that XB5850668.L is a member of the SULT2 family that plays important roles in patterning the embryonic ectoderm. Some aspects of its influence likely depend on sulfotransferase activity.
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Affiliation(s)
- Alexander Marchak
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Karen M Neilson
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Himani D Majumdar
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Kiyoshi Yamauchi
- Department of Biological Science, Shizuoka University, Shizuoka, Japan
| | - Steven L Klein
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Sally A Moody
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
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3
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Liu B, Ren X, Satou Y. BMP signaling is required to form the anterior neural plate border in ascidian embryos. Dev Genes Evol 2023:10.1007/s00427-023-00702-0. [PMID: 37079132 DOI: 10.1007/s00427-023-00702-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 03/29/2023] [Indexed: 04/21/2023]
Abstract
Cranial neurogenic placodes have been considered vertebrate innovations. However, anterior neural plate border (ANB) cells of ascidian embryos share many properties with vertebrate neurogenic placodes; therefore, it is now believed that the last common ancestor of vertebrates and ascidians had embryonic structures similar to neurogenic placodes of vertebrate embryos. Because BMP signaling is important for specifying the placode region in vertebrate embryos, we examined whether BMP signaling is also involved in gene expression in the ANB region of ascidian embryos. Our data indicated that Admp, a divergent BMP family member, is mainly responsible for BMP signaling in the ANB region, and that two BMP-antagonists, Noggin and Chordin, restrict the domain, in which BMP signaling is activated, to the ANB region, and prevent it from expanding to the neural plate. BMP signaling is required for expression of Foxg and Six1/2 at the late gastrula stage, and also for expression of Zf220, which encodes a zinc finger transcription factor in late neurula embryos. Because Zf220 negatively regulates Foxg, when we downregulated Zf220 by inhibiting BMP signaling, Foxg was upregulated, resulting in one large palp instead of three palps (adhesive organs derived from ANB cells). Functions of BMP signaling in specification of the ANB region give further support to the hypothesis that ascidian ANB cells share an evolutionary origin with vertebrate cranial placodes.
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Affiliation(s)
- Boqi Liu
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502, Japan
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University-Peking University Joint Center for Life Sciences, Tsinghua University, Beijing, China
| | - Ximan Ren
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502, Japan
| | - Yutaka Satou
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502, Japan.
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4
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Keer S, Cousin H, Jourdeuil K, Neilson KM, Tavares ALP, Alfandari D, Moody SA. Mcrs1 is required for branchial arch and cranial cartilage development. Dev Biol 2022; 489:62-75. [PMID: 35697116 PMCID: PMC10426812 DOI: 10.1016/j.ydbio.2022.06.002] [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: 02/04/2022] [Revised: 06/06/2022] [Accepted: 06/08/2022] [Indexed: 11/22/2022]
Abstract
Mcrs1 is a multifunctional protein that is critical for many cellular processes in a wide range of cell types. Previously, we showed that Mcrs1 binds to the Six1 transcription factor and reduces the ability of the Six1-Eya1 complex to upregulate transcription, and that Mcrs1 loss-of-function leads to the expansion of several neural plate genes, reduction of neural border and pre-placodal ectoderm (PPR) genes, and pleiotropic effects on various neural crest (NC) genes. Because the affected embryonic structures give rise to several of the cranial tissues affected in Branchio-otic/Branchio-oto-renal (BOR) syndrome, herein we tested whether these gene expression changes subsequently alter the development of the proximate precursors of BOR affected structures - the otic vesicles (OV) and branchial arches (BA). We found that Mcrs1 is required for the expression of several OV genes involved in inner ear formation, patterning and otic capsule cartilage formation. Mcrs1 knockdown also reduced the expression domains of many genes expressed in the larval BA, derived from either NC or PPR, except for emx2, which was expanded. Reduced Mcrs1 also diminished the length of the expression domain of tbx1 in BA1 and BA2 and interfered with cranial NC migration from the dorsal neural tube; this subsequently resulted in defects in the morphology of lower jaw cartilages derived from BA1 and BA2, including the infrarostral, Meckel's, and ceratohyal as well as the otic capsule. These results demonstrate that Mcrs1 plays an important role in processes that lead to the formation of craniofacial cartilages and its loss results in phenotypes consistent with reduced Six1 activity associated with BOR.
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Affiliation(s)
- Stephanie Keer
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, NW, Washington, DC, 20037, USA
| | - Helene Cousin
- Department of Animal Science, University of Massachusetts Amherst, Integrated Science Building, 661 N. Pleasant Street, Amherst, MA, 01003, USA
| | - Karyn Jourdeuil
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, NW, Washington, DC, 20037, USA
| | - Karen M Neilson
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, NW, Washington, DC, 20037, USA
| | - Andre L P Tavares
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, NW, Washington, DC, 20037, USA
| | - Dominique Alfandari
- Department of Animal Science, University of Massachusetts Amherst, Integrated Science Building, 661 N. Pleasant Street, Amherst, MA, 01003, USA
| | - Sally A Moody
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, NW, Washington, DC, 20037, USA.
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5
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Stundl J, Bertucci PY, Lauri A, Arendt D, Bronner ME. Evolution of new cell types at the lateral neural border. Curr Top Dev Biol 2021; 141:173-205. [PMID: 33602488 DOI: 10.1016/bs.ctdb.2020.11.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
During the course of evolution, animals have become increasingly complex by the addition of novel cell types and regulatory mechanisms. A prime example is represented by the lateral neural border, known as the neural plate border in vertebrates, a region of the developing ectoderm where presumptive neural and non-neural tissue meet. This region has been intensively studied as the source of two important embryonic cell types unique to vertebrates-the neural crest and the ectodermal placodes-which contribute to diverse differentiated cell types including the peripheral nervous system, pigment cells, bone, and cartilage. How did these multipotent progenitors originate in animal evolution? What triggered the elaboration of the border during the course of chordate evolution? How is the lateral neural border patterned in various bilaterians and what is its fate? Here, we review and compare the development and fate of the lateral neural border in vertebrates and invertebrates and we speculate about its evolutionary origin. Taken together, the data suggest that the lateral neural border existed in bilaterian ancestors prior to the origin of vertebrates and became a developmental source of exquisite evolutionary change that frequently enabled the acquisition of new cell types.
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Affiliation(s)
- Jan Stundl
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | | | | | - Detlev Arendt
- European Molecular Biology Laboratory, Heidelberg, Germany.
| | - Marianne E Bronner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States.
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6
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Thawani A, Groves AK. Building the Border: Development of the Chordate Neural Plate Border Region and Its Derivatives. Front Physiol 2020; 11:608880. [PMID: 33364980 PMCID: PMC7750469 DOI: 10.3389/fphys.2020.608880] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 11/19/2020] [Indexed: 01/04/2023] Open
Abstract
The paired cranial sensory organs and peripheral nervous system of vertebrates arise from a thin strip of cells immediately adjacent to the developing neural plate. The neural plate border region comprises progenitors for four key populations of cells: neural plate cells, neural crest cells, the cranial placodes, and epidermis. Putative homologues of these neural plate border derivatives can be found in protochordates such as amphioxus and tunicates. In this review, we summarize key signaling pathways and transcription factors that regulate the inductive and patterning events at the neural plate border region that give rise to the neural crest and placodal lineages. Gene regulatory networks driven by signals from WNT, fibroblast growth factor (FGF), and bone morphogenetic protein (BMP) signaling primarily dictate the formation of the crest and placodal lineages. We review these studies and discuss the potential of recent advances in spatio-temporal transcriptomic and epigenomic analyses that would allow a mechanistic understanding of how these signaling pathways and their downstream transcriptional cascades regulate the formation of the neural plate border region.
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Affiliation(s)
- Ankita Thawani
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Andrew K Groves
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
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7
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Cell fate decisions during the development of the peripheral nervous system in the vertebrate head. Curr Top Dev Biol 2020; 139:127-167. [PMID: 32450959 DOI: 10.1016/bs.ctdb.2020.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Sensory placodes and neural crest cells are among the key cell populations that facilitated the emergence and diversification of vertebrates throughout evolution. Together, they generate the sensory nervous system in the head: both form the cranial sensory ganglia, while placodal cells make major contributions to the sense organs-the eye, ear and olfactory epithelium. Both are instrumental for integrating craniofacial organs and have been key to drive the concentration of sensory structures in the vertebrate head allowing the emergence of active and predatory life forms. Whereas the gene regulatory networks that control neural crest cell development have been studied extensively, the signals and downstream transcriptional events that regulate placode formation and diversity are only beginning to be uncovered. Both cell populations are derived from the embryonic ectoderm, which also generates the central nervous system and the epidermis, and recent evidence suggests that their initial specification involves a common molecular mechanism before definitive neural, neural crest and placodal lineages are established. In this review, we will first discuss the transcriptional networks that pattern the embryonic ectoderm and establish these three cell fates with emphasis on sensory placodes. Second, we will focus on how sensory placode precursors diversify using the specification of otic-epibranchial progenitors and their segregation as an example.
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8
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Wang L, Xie J, Zhang H, Tsang LH, Tsang SL, Braune EB, Lendahl U, Sham MH. Notch signalling regulates epibranchial placode patterning and segregation. Development 2020; 147:dev.183665. [PMID: 31988190 PMCID: PMC7044445 DOI: 10.1242/dev.183665] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 01/14/2020] [Indexed: 11/20/2022]
Abstract
Epibranchial placodes are the geniculate, petrosal and nodose placodes that generate parts of cranial nerves VII, IX and X, respectively. How the three spatially separated placodes are derived from the common posterior placodal area is poorly understood. Here, we reveal that the broad posterior placode area is first patterned into a Vgll2+/Irx5+ rostral domain and a Sox2+/Fgf3+/Etv5+ caudal domain relative to the first pharyngeal cleft. This initial rostral and caudal patterning is then sequentially repeated along each pharyngeal cleft for each epibranchial placode. The caudal domains give rise to the neuronal and non-neuronal cells in the placode, whereas the rostral domains are previously unrecognized structures, serving as spacers between the final placodes. Notch signalling regulates the balance between the rostral and caudal domains: high levels of Notch signalling expand the caudal domain at the expense of the rostral domain, whereas loss of Notch signalling produces the converse phenotype. Collectively, these data unravel a new patterning principle for the early phases of epibranchial placode development and a role for Notch signalling in orchestrating epibranchial placode segregation and differentiation.
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Affiliation(s)
- Li Wang
- School of Biomedical Sciences, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Junjie Xie
- School of Biomedical Sciences, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Haoran Zhang
- School of Biomedical Sciences, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Long Hin Tsang
- School of Biomedical Sciences, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Sze Lan Tsang
- School of Biomedical Sciences, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Eike-Benjamin Braune
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, SE-171 77, Sweden
| | - Urban Lendahl
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, SE-171 77, Sweden
| | - Mai Har Sham
- School of Biomedical Sciences, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
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9
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Sullivan CH, Majumdar HD, Neilson KM, Moody SA. Six1 and Irx1 have reciprocal interactions during cranial placode and otic vesicle formation. Dev Biol 2019; 446:68-79. [PMID: 30529252 PMCID: PMC6349505 DOI: 10.1016/j.ydbio.2018.12.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 12/02/2018] [Accepted: 12/03/2018] [Indexed: 01/04/2023]
Abstract
The specialized sensory organs of the vertebrate head are derived from thickened patches of cells in the ectoderm called cranial sensory placodes. The developmental program that generates these placodes and the genes that are expressed during the process have been studied extensively in a number of animals, yet very little is known about how these genes regulate one another. We previously found via a microarray screen that Six1, a known transcriptional regulator of cranial placode fate, up-regulates Irx1 in ectodermal explants. In this study, we investigated the transcriptional relationship between Six1 and Irx1 and found that they reciprocally regulate each other throughout cranial placode and otic vesicle formation. Although Irx1 expression precedes that of Six1 in the neural border zone, its continued and appropriately patterned expression in the pre-placodal region (PPR) and otic vesicle requires Six1. At early PPR stages, Six1 expands the Irx1 domain, but this activity subsides over time and changes to a predominantly repressive effect. Likewise, Irx1 initially expands Six1 expression in the PPR, but later represses it. We also found that Irx1 and Sox11, a known direct target of Six1, reciprocally affect each other. This work demonstrates that the interactions between Six1 and Irx1 are continuous during PPR and placode development and their transcriptional effects on one another change over developmental time.
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Affiliation(s)
- Charles H Sullivan
- Department of Biology, Grinnell College, Grinnell, IA, 50112, USA; bDepartment of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, N.W., Washington DC 20037, USA
| | - Himani D Majumdar
- bDepartment of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, N.W., Washington DC 20037, USA
| | - Karen M Neilson
- bDepartment of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, N.W., Washington DC 20037, USA
| | - Sally A Moody
- bDepartment of Anatomy and Cell Biology, George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, N.W., Washington DC 20037, USA.
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10
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Watanabe T, Yamamoto T, Tsukano K, Hirano S, Horikawa A, Michiue T. Fam46a regulates BMP-dependent pre-placodal ectoderm differentiation in Xenopus. Development 2018; 145:dev.166710. [PMID: 30291163 DOI: 10.1242/dev.166710] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Accepted: 09/06/2018] [Indexed: 12/30/2022]
Abstract
The pre-placodal ectoderm (PPE) is a specialized ectodermal region which gives rise to the sensory organs and other systems. The PPE is induced from the neural plate border during neurulation, but the molecular mechanism of PPE formation is not fully understood. In this study, we examined the role of a newly identified PPE gene, Fam46a, during embryogenesis. Fam46a contains a nucleoside triphosphate transferase domain, but its function in early development was previously unclear. We show that Fam46a is expressed in the PPE in Xenopus embryos, and Fam46a knockdown induces abnormalities in the eye formation and the body color. At the neurula stage, Fam46a upregulates the expression of PPE genes and inhibits neural crest formation. We also show that Fam46a physically interacts with Smad1/Smad4 and positively regulates BMP signaling. From these results, we conclude that Fam46a is required for PPE formation via the positive regulation of BMP signaling. Our study provides a new mechanism of ectodermal patterning via cell-autonomous regulation of BMP signaling in the PPE.
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Affiliation(s)
- Tomoko Watanabe
- Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Takayoshi Yamamoto
- Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Kohei Tsukano
- Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Sayuki Hirano
- Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Ayumi Horikawa
- Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Tatsuo Michiue
- Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo 153-8902, Japan
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11
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Ma JY, You D, Li WY, Lu XL, Sun S, Li HW. Bone morphogenetic proteins and inner ear development. J Zhejiang Univ Sci B 2018; 20:131-145. [PMID: 30112880 DOI: 10.1631/jzus.b1800084] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Bone morphogenetic proteins (BMPs) are the largest subfamily of the transforming growth factor-β superfamily, and they play important roles in the development of numerous organs, including the inner ear. The inner ear is a relatively small organ but has a highly complex structure and is involved in both hearing and balance. Here, we discuss BMPs and BMP signaling pathways and then focus on the role of BMP signal pathway regulation in the development of the inner ear and the implications this has for the treatment of human hearing loss and balance dysfunction.
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Affiliation(s)
- Jiao-Yao Ma
- Ear, Nose & Throat Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, NHC Key Laboratory of Hearing Medicine, Shanghai Engineering Research Centre of Cochlear Implant, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200031, China
| | - Dan You
- Ear, Nose & Throat Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, NHC Key Laboratory of Hearing Medicine, Shanghai Engineering Research Centre of Cochlear Implant, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200031, China
| | - Wen-Yan Li
- Ear, Nose & Throat Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, NHC Key Laboratory of Hearing Medicine, Shanghai Engineering Research Centre of Cochlear Implant, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200031, China
| | - Xiao-Ling Lu
- Ear, Nose & Throat Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, NHC Key Laboratory of Hearing Medicine, Shanghai Engineering Research Centre of Cochlear Implant, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200031, China
| | - Shan Sun
- Ear, Nose & Throat Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, NHC Key Laboratory of Hearing Medicine, Shanghai Engineering Research Centre of Cochlear Implant, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200031, China
| | - Hua-Wei Li
- Ear, Nose & Throat Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, NHC Key Laboratory of Hearing Medicine, Shanghai Engineering Research Centre of Cochlear Implant, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200031, China.,Institutes of Biomedical Sciences and the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China
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12
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Pla P, Monsoro-Burq AH. The neural border: Induction, specification and maturation of the territory that generates neural crest cells. Dev Biol 2018; 444 Suppl 1:S36-S46. [PMID: 29852131 DOI: 10.1016/j.ydbio.2018.05.018] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Revised: 05/23/2018] [Accepted: 05/23/2018] [Indexed: 11/17/2022]
Abstract
The neural crest is induced at the edge between the neural plate and the nonneural ectoderm, in an area called the neural (plate) border, during gastrulation and neurulation. In recent years, many studies have explored how this domain is patterned, and how the neural crest is induced within this territory, that also participates to the prospective dorsal neural tube, the dorsalmost nonneural ectoderm, as well as placode derivatives in the anterior area. This review highlights the tissue interactions, the cell-cell signaling and the molecular mechanisms involved in this dynamic spatiotemporal patterning, resulting in the induction of the premigratory neural crest. Collectively, these studies allow building a complex neural border and early neural crest gene regulatory network, mostly composed by transcriptional regulations but also, more recently, including novel signaling interactions.
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Affiliation(s)
- Patrick Pla
- Univ. Paris Sud, Université Paris Saclay, CNRS UMR 3347, INSERM U1021, Centre Universitaire, 15, rue Georges Clémenceau, F-91405 Orsay, France; Institut Curie Research Division, PSL Research University, CNRS UMR 3347, INSERM U1021, F-91405 Orsay, France
| | - Anne H Monsoro-Burq
- Univ. Paris Sud, Université Paris Saclay, CNRS UMR 3347, INSERM U1021, Centre Universitaire, 15, rue Georges Clémenceau, F-91405 Orsay, France; Institut Curie Research Division, PSL Research University, CNRS UMR 3347, INSERM U1021, F-91405 Orsay, France; Institut Universitaire de France, F-75005, Paris.
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13
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Dubey A, Rose RE, Jones DR, Saint-Jeannet JP. Generating retinoic acid gradients by local degradation during craniofacial development: One cell's cue is another cell's poison. Genesis 2018; 56:10.1002/dvg.23091. [PMID: 29330906 PMCID: PMC5818312 DOI: 10.1002/dvg.23091] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 01/08/2018] [Accepted: 01/09/2018] [Indexed: 01/02/2023]
Abstract
Retinoic acid (RA) is a vital morphogen for early patterning and organogenesis in the developing embryo. RA is a diffusible, lipophilic molecule that signals via nuclear RA receptor heterodimeric units that regulate gene expression by interacting with RA response elements in promoters of a significant number of genes. For precise RA signaling, a robust gradient of the morphogen is required. The developing embryo contains regions that produce RA, and specific intracellular concentrations of RA are created through local degradation mediated by Cyp26 enzymes. In order to elucidate the mechanisms by which RA executes precise developmental programs, the kinetics of RA metabolism must be clearly understood. Recent advances in techniques for endogenous RA detection and quantification have paved the way for mechanistic studies to shed light on downstream gene expression regulation coordinated by RA. It is increasingly coming to light that RA signaling operates not only at precise concentrations but also employs mechanisms of degradation and feedback inhibition to self-regulate its levels. A global gradient of RA throughout the embryo is often found concurrently with several local gradients, created by juxtaposed domains of RA synthesis and degradation. The existence of such local gradients has been found especially critical for the proper development of craniofacial structures that arise from the neural crest and the cranial placode populations. In this review, we summarize the current understanding of how local gradients of RA are established in the embryo and their impact on craniofacial development.
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Affiliation(s)
- Aditi Dubey
- Department of Basic Science and Craniofacial Biology, New York University College of Dentistry
| | - Rebecca E. Rose
- Department of Biochemistry and Molecular Pharmacology, New York University Langone Health, New York, NY, USA
| | - Drew R. Jones
- Department of Biochemistry and Molecular Pharmacology, New York University Langone Health, New York, NY, USA
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14
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Perny M, Ting CC, Kleinlogel S, Senn P, Roccio M. Generation of Otic Sensory Neurons from Mouse Embryonic Stem Cells in 3D Culture. Front Cell Neurosci 2017; 11:409. [PMID: 29311837 PMCID: PMC5742223 DOI: 10.3389/fncel.2017.00409] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 12/05/2017] [Indexed: 12/29/2022] Open
Abstract
The peripheral hearing process taking place in the cochlea mainly depends on two distinct sensory cell types: the mechanosensitive hair cells and the spiral ganglion neurons (SGNs). The first respond to the mechanical stimulation exerted by sound pressure waves on their hair bundles by releasing neurotransmitters and thereby activating the latter. Loss of these sensorineural cells is associated with permanent hearing loss. Stem cell-based approaches aiming at cell replacement or in vitro drug testing to identify potential ototoxic, otoprotective, or regenerative compounds have lately gained attention as putative therapeutic strategies for hearing loss. Nevertheless, they rely on efficient and reliable protocols for the in vitro generation of cochlear sensory cells for their implementation. To this end, we have developed a differentiation protocol based on organoid culture systems, which mimics the most important steps of in vivo otic development, robustly guiding mouse embryonic stem cells (mESCs) toward otic sensory neurons (OSNs). The stepwise differentiation of mESCs toward ectoderm was initiated using a quick aggregation method in presence of Matrigel in serum-free conditions. Non-neural ectoderm was induced via activation of bone morphogenetic protein (BMP) signaling and concomitant inhibition of transforming growth factor beta (TGFβ) signaling to prevent mesendoderm induction. Preplacodal and otic placode ectoderm was further induced by inhibition of BMP signaling and addition of fibroblast growth factor 2 (FGF2). Delamination and differentiation of SGNs was initiated by plating of the organoids on a 2D Matrigel-coated substrate. Supplementation with brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) was used for further maturation until 15 days of in vitro differentiation. A large population of neurons with a clear bipolar morphology and functional excitability was derived from these cultures. Immunostaining and gene expression analysis performed at different time points confirmed the transition trough the otic lineage and final expression of the key OSN markers. Moreover, the stem cell-derived OSNs exhibited functional electrophysiological properties of native SGNs. Our established in vitro model of OSNs development can be used for basic developmental studies, for drug screening or for the exploration of their regenerative potential.
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Affiliation(s)
- Michael Perny
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, Department for BioMedical Research, University of Bern, Bern, Switzerland.,Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Ching-Chia Ting
- Laboratory of Inner Ear Research, Department for BioMedical Research, University of Bern, Bern, Switzerland.,Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department of Biomedical Research, University of Bern, Bern, Switzerland
| | | | - Pascal Senn
- Laboratory of Inner Ear Research, Department for BioMedical Research, University of Bern, Bern, Switzerland.,Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department of Biomedical Research, University of Bern, Bern, Switzerland.,Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Geneva (HUG), Geneva, Switzerland
| | - Marta Roccio
- Laboratory of Inner Ear Research, Department for BioMedical Research, University of Bern, Bern, Switzerland.,Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department of Biomedical Research, University of Bern, Bern, Switzerland
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15
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Chen J, Tambalo M, Barembaum M, Ranganathan R, Simões-Costa M, Bronner ME, Streit A. A systems-level approach reveals new gene regulatory modules in the developing ear. Development 2017; 144:1531-1543. [PMID: 28264836 PMCID: PMC5399671 DOI: 10.1242/dev.148494] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 02/24/2017] [Indexed: 01/23/2023]
Abstract
The inner ear is a complex vertebrate sense organ, yet it arises from a simple epithelium, the otic placode. Specification towards otic fate requires diverse signals and transcriptional inputs that act sequentially and/or in parallel. Using the chick embryo, we uncover novel genes in the gene regulatory network underlying otic commitment and reveal dynamic changes in gene expression. Functional analysis of selected transcription factors reveals the genetic hierarchy underlying the transition from progenitor to committed precursor, integrating known and novel molecular players. Our results not only characterize the otic transcriptome in unprecedented detail, but also identify new gene interactions responsible for inner ear development and for the segregation of the otic lineage from epibranchial progenitors. By recapitulating the embryonic programme, the genes and genetic sub-circuits discovered here might be useful for reprogramming naïve cells towards otic identity to restore hearing loss. Summary: Transcriptome analysis and knock down of select transcription factors reveals a genetic hierarchy as cells become committed to inner ear fate.
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Affiliation(s)
- Jingchen Chen
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London SE1 9RT, UK
| | - Monica Tambalo
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London SE1 9RT, UK
| | - Meyer Barembaum
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Ramya Ranganathan
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London SE1 9RT, UK
| | - Marcos Simões-Costa
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Marianne E Bronner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Andrea Streit
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London SE1 9RT, UK
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16
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Neilson KM, Abbruzzesse G, Kenyon K, Bartolo V, Krohn P, Alfandari D, Moody SA. Pa2G4 is a novel Six1 co-factor that is required for neural crest and otic development. Dev Biol 2017; 421:171-182. [PMID: 27940157 PMCID: PMC5221411 DOI: 10.1016/j.ydbio.2016.11.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 11/15/2016] [Accepted: 11/28/2016] [Indexed: 11/29/2022]
Abstract
Mutations in SIX1 and in its co-factor, EYA1, underlie Branchiootorenal Spectrum disorder (BOS), which is characterized by variable branchial arch, otic and kidney malformations. However, mutations in these two genes are identified in only half of patients. We screened for other potential co-factors, and herein characterize one of them, Pa2G4 (aka Ebp1/Plfap). In human embryonic kidney cells, Pa2G4 binds to Six1 and interferes with the Six1-Eya1 complex. In Xenopus embryos, knock-down of Pa2G4 leads to down-regulation of neural border zone, neural crest and cranial placode genes, and concomitant expansion of neural plate genes. Gain-of-function leads to a broader neural border zone, expanded neural crest and altered cranial placode domains. In loss-of-function assays, the later developing otocyst is reduced in size, which impacts gene expression. In contrast, the size of the otocyst in gain-of-function assays is not changed but the expression domains of several otocyst genes are reduced. Together these findings establish an interaction between Pa2G4 and Six1, and demonstrate that it has an important role in the development of tissues affected in BOS. Thereby, we suggest that pa2g4 is a potential candidate gene for BOS.
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Affiliation(s)
- Karen M Neilson
- Department of Anatomy and Regenerative Biology, George Washington University, School of Medicine and Health Sciences, Washington, DC, USA
| | - Genevieve Abbruzzesse
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, MA, USA
| | - Kristy Kenyon
- Department of Biology, Hobart and William Smith Colleges, Geneva, NY, USA
| | - Vanessa Bartolo
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, MA, USA
| | - Patrick Krohn
- Department of Anatomy and Regenerative Biology, George Washington University, School of Medicine and Health Sciences, Washington, DC, USA
| | - Dominique Alfandari
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, MA, USA
| | - Sally A Moody
- Department of Anatomy and Regenerative Biology, George Washington University, School of Medicine and Health Sciences, Washington, DC, USA.
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17
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Cardeña-Núñez S, Sánchez-Guardado LÓ, Corral-San-Miguel R, Rodríguez-Gallardo L, Marín F, Puelles L, Aroca P, Hidalgo-Sánchez M. Expression patterns of Irx genes in the developing chick inner ear. Brain Struct Funct 2016; 222:2071-2092. [PMID: 27783221 DOI: 10.1007/s00429-016-1326-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 10/14/2016] [Indexed: 10/20/2022]
Abstract
The vertebrate inner ear is a complex three-dimensional sensorial structure with auditory and vestibular functions. The molecular patterning of the developing otic epithelium creates various positional identities, consequently leading to the stereotyped specification of each neurosensory and non-sensory element of the membranous labyrinth. The Iroquois (Iro/Irx) genes, clustered in two groups (A: Irx1, Irx2, and Irx4; and B: Irx3, Irx5, and Irx6), encode for transcriptional factors involved directly in numerous patterning processes of embryonic tissues in many phyla. This work presents a detailed study of the expression patterns of these six Irx genes during chick inner ear development, paying particular attention to the axial specification of the otic anlagen. The Irx genes seem to play different roles at different embryonic periods. At the otic vesicle stage (HH18), all the genes of each cluster are expressed identically. Both clusters A and B seem involved in the specification of the lateral and posterior portions of the otic anlagen. Cluster B seems to regulate a larger area than cluster A, including the presumptive territory of the endolymphatic apparatus. Both clusters seem also to be involved in neurogenic events. At stages HH24/25-HH27, combinations of IrxA and IrxB genes participate in the specification of most sensory patches and some non-sensory components of the otic epithelium. At stage HH34, the six Irx genes show divergent patterns of expression, leading to the final specification of the membranous labyrinth, as well as to cell differentiation.
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Affiliation(s)
- Sheila Cardeña-Núñez
- Department of Cell Biology, School of Science, University of Extremadura, Avda de Elvas s/n, E06071, Badajoz, Spain
| | - Luis Óscar Sánchez-Guardado
- Department of Cell Biology, School of Science, University of Extremadura, Avda de Elvas s/n, E06071, Badajoz, Spain
| | - Rubén Corral-San-Miguel
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de La Arrixaca (IMIB-Arrixaca), E30100, Murcia, Spain
| | - Lucía Rodríguez-Gallardo
- Department of Cell Biology, School of Science, University of Extremadura, Avda de Elvas s/n, E06071, Badajoz, Spain
| | - Faustino Marín
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de La Arrixaca (IMIB-Arrixaca), E30100, Murcia, Spain
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de La Arrixaca (IMIB-Arrixaca), E30100, Murcia, Spain
| | - Pilar Aroca
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de La Arrixaca (IMIB-Arrixaca), E30100, Murcia, Spain
| | - Matías Hidalgo-Sánchez
- Department of Cell Biology, School of Science, University of Extremadura, Avda de Elvas s/n, E06071, Badajoz, Spain.
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18
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Cain CJ, Gaborit N, Lwin W, Barruet E, Ho S, Bonnard C, Hamamy H, Shboul M, Reversade B, Kayserili H, Bruneau BG, Hsiao EC. Loss of Iroquois homeobox transcription factors 3 and 5 in osteoblasts disrupts cranial mineralization. Bone Rep 2016; 5:86-95. [PMID: 27453922 PMCID: PMC4926823 DOI: 10.1016/j.bonr.2016.02.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 02/02/2016] [Indexed: 01/13/2023] Open
Abstract
Cranial malformations are a significant cause of perinatal morbidity and mortality. Iroquois homeobox transcription factors (IRX) are expressed early in bone tissue formation and facilitate patterning and mineralization of the skeleton. Mice lacking Irx5 appear grossly normal, suggesting that redundancy within the Iroquois family. However, global loss of both Irx3 and Irx5 in mice leads to significant skeletal malformations and embryonic lethality from cardiac defects. Here, we study the bone-specific functions of Irx3 and Irx5 using Osx-Cre to drive osteoblast lineage-specific deletion of Irx3 in Irx5(-/-) mice. Although we found that the Osx-Cre transgene alone could also affect craniofacial mineralization, newborn Irx3 (flox/flox) /Irx5(-/-)/Osx-Cre (+) mice displayed additional mineralization defects in parietal, interparietal, and frontal bones with enlarged sutures and reduced calvarial expression of osteogenic genes. Newborn endochondral long bones were largely unaffected, but we observed marked reductions in 3-4-week old bone mineral content of Irx3 (flox/flox) /Irx5(-/-)/Osx-Cre (+) mice. Our findings indicate that IRX3 and IRX5 can work together to regulate mineralization of specific cranial bones. Our results also provide insight into the causes of the skeletal changes and mineralization defects seen in Hamamy syndrome patients carrying mutations in IRX5.
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Affiliation(s)
- Corey J Cain
- Department of Medicine, Division of Endocrinology and Metabolism, Institute for Human Genetics, Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA 94143-0794, USA
| | - Nathalie Gaborit
- Inserm, UMR 1087, l'institut du thorax, Nantes, France; CNRS, UMR 6291, Nantes, France; Université de Nantes, France
| | - Wint Lwin
- Department of Medicine, Division of Endocrinology and Metabolism, Institute for Human Genetics, Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA 94143-0794, USA
| | - Emilie Barruet
- Department of Medicine, Division of Endocrinology and Metabolism, Institute for Human Genetics, Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA 94143-0794, USA
| | - Samantha Ho
- Department of Medicine, Division of Endocrinology and Metabolism, Institute for Human Genetics, Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA 94143-0794, USA
| | - Carine Bonnard
- Human Embryology and Genetics Laboratory, Institute of Medical Biology, ASTAR, Singapore 138648, Singapore
| | - Hanan Hamamy
- Department of Genetic Medicine and Development, Geneva University, Geneva 1211, Switzerland
| | - Mohammad Shboul
- Human Embryology and Genetics Laboratory, Institute of Medical Biology, ASTAR, Singapore 138648, Singapore
| | - Bruno Reversade
- Human Embryology and Genetics Laboratory, Institute of Medical Biology, ASTAR, Singapore 138648, Singapore
| | - Hülya Kayserili
- Medical Genetics Department, Koc University School of Medicine, Rumelifeneri Yolu, Sarıyer, Istanbul 34450, Turkey; Medical Genetics Department, Istanbul Medical Faculty, Istanbul University Topkapi, Fatih, 34093 lstanbul, Turkey
| | - Benoit G Bruneau
- Gladstone Institute for Cardiovascular Disease, San Francisco, CA 94158, USA; Department of Pediatrics, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Edward C Hsiao
- Department of Medicine, Division of Endocrinology and Metabolism, Institute for Human Genetics, Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA 94143-0794, USA
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19
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Aguillon R, Blader P, Batut J. Patterning, morphogenesis, and neurogenesis of zebrafish cranial sensory placodes. Methods Cell Biol 2016; 134:33-67. [PMID: 27312490 DOI: 10.1016/bs.mcb.2016.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Peripheral sensory organs and ganglia found in the vertebrate head arise during embryonic development from distinct ectodermal thickenings, called cranial sensory placodes (adenohypophyseal, olfactory, lens, trigeminal, epibranchial, and otic). A series of patterning events leads to the establishment of these placodes. Subsequently, these placodes undergo specific morphogenetic movements and cell-type specification in order to shape the final placodal derivatives and to produce differentiated cell types necessary for their function. In this chapter, we will focus on recent studies in the zebrafish that have advanced our understanding of cranial sensory placode development. We will summarize the signaling events and their molecular effectors guiding the formation of the so-called preplacodal region, and the subsequent subdivision of this region along the anteroposterior axis that gives rise to specific placode identities as well as those controlling morphogenesis and neurogenesis. Finally, we will highlight the approaches used in zebrafish that have been established to precisely label cell populations, to follow their development, and/or to characterize cell fates within a specific placode.
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Affiliation(s)
- R Aguillon
- Centre de Biologie du Développement (CBD, UMR5547), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - P Blader
- Centre de Biologie du Développement (CBD, UMR5547), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - J Batut
- Centre de Biologie du Développement (CBD, UMR5547), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
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20
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Jidigam VK, Srinivasan RC, Patthey C, Gunhaga L. Apical constriction and epithelial invagination are regulated by BMP activity. Biol Open 2015; 4:1782-91. [PMID: 26621830 PMCID: PMC4736041 DOI: 10.1242/bio.015263] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Epithelial invagination is a morphological process in which flat cell sheets transform into three-dimensional structures through bending of the tissue. It is accompanied by apical constriction, in which the apical cell surface is reduced in relation to the basal cell surface. Although much is known about the intra-cellular molecular machinery driving apical constriction and epithelial invagination, information of how extra-cellular signals affect these processes remains insufficient. In this study we have established several in vivo assays of placodal invagination to explore whether the external signal BMP regulates processes connected to epithelial invagination. By inhibiting BMP activity in prospective cranial placodes, we provide evidence that BMP signals are required for RhoA and F-actin rearrangements, apical constriction, cell elongation and epithelial invagination. The failure of placode invagination after BMP inhibition appears to be a direct consequence of disrupted apical accumulation of RhoA and F-actin, rather than changes in cell death or proliferation. In addition, our results show that epithelial invagination and acquisition of placode-specific identities are two distinct and separable developmental processes. In summary, our results provide evidence that BMP signals promote epithelial invagination by acting upstream of the intracellular molecular machinery that drives apical constriction and cell elongation. Summary: We describe a novel role for BMP activity in promoting a direct and cell type-independent mechanism for apical constriction, cell elongation and epithelial invagination, separate from acquisition of placode-specific identities.
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Affiliation(s)
- Vijay K Jidigam
- Umeå Centre for Molecular Medicine, Umeå University, Umeå S-901 87, Sweden
| | | | - Cedric Patthey
- Umeå Centre for Molecular Medicine, Umeå University, Umeå S-901 87, Sweden
| | - Lena Gunhaga
- Umeå Centre for Molecular Medicine, Umeå University, Umeå S-901 87, Sweden
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21
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Vega‐López GA, Bonano M, Tríbulo C, Fernández JP, Agüero TH, Aybar MJ. Functional analysis of
Hairy
genes in
Xenopus
neural crest initial specification and cell migration. Dev Dyn 2015; 244:988-1013. [DOI: 10.1002/dvdy.24295] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 04/25/2015] [Accepted: 05/14/2015] [Indexed: 01/28/2023] Open
Affiliation(s)
| | - Marcela Bonano
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET‐UNT
| | - Celeste Tríbulo
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET‐UNT
- Instituto de Biología “Dr. Francisco D. Barbieri”, Facultad de Bioquímica, Química y FarmaciaUniversidad Nacional de TucumánChacabuco San Miguel de Tucumán Argentina
| | - Juan P. Fernández
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET‐UNT
| | - Tristán H. Agüero
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET‐UNT
| | - Manuel J. Aybar
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET‐UNT
- Instituto de Biología “Dr. Francisco D. Barbieri”, Facultad de Bioquímica, Química y FarmaciaUniversidad Nacional de TucumánChacabuco San Miguel de Tucumán Argentina
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22
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Abstract
Cranial sensory placodes derive from discrete patches of the head ectoderm and give rise to numerous sensory structures. During gastrulation, a specialized "neural border zone" forms around the neural plate in response to interactions between the neural and nonneural ectoderm and signals from adjacent mesodermal and/or endodermal tissues. This zone subsequently gives rise to two distinct precursor populations of the peripheral nervous system: the neural crest and the preplacodal ectoderm (PPE). The PPE is a common field from which all cranial sensory placodes arise (adenohypophyseal, olfactory, lens, trigeminal, epibranchial, otic). Members of the Six family of transcription factors are major regulators of PPE specification, in partnership with cofactor proteins such as Eya. Six gene activity also maintains tissue boundaries between the PPE, neural crest, and epidermis by repressing genes that specify the fates of those adjacent ectodermally derived domains. As the embryo acquires anterior-posterior identity, the PPE becomes transcriptionally regionalized, and it subsequently becomes subdivided into specific placodes with distinct developmental fates in response to signaling from adjacent tissues. Each placode is characterized by a unique transcriptional program that leads to the differentiation of highly specialized cells, such as neurosecretory cells, sensory receptor cells, chemosensory neurons, peripheral glia, and supporting cells. In this review, we summarize the transcriptional and signaling factors that regulate key steps of placode development, influence subsequent sensory neuron specification, and discuss what is known about mutations in some of the essential PPE genes that underlie human congenital syndromes.
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Affiliation(s)
- Sally A Moody
- Department of Anatomy and Regenerative Biology, The George Washington University, School of Medicine and Health Sciences, Washington, DC, USA; George Washington University Institute for Neuroscience, Washington, DC, USA.
| | - Anthony-Samuel LaMantia
- George Washington University Institute for Neuroscience, Washington, DC, USA; Department of Pharmacology and Physiology, The George Washington University, School of Medicine and Health Sciences, Washington, DC, USA
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23
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Rashid DJ, Chapman SC, Larsson HC, Organ CL, Bebin AG, Merzdorf CS, Bradley R, Horner JR. From dinosaurs to birds: a tail of evolution. EvoDevo 2014; 5:25. [PMID: 25621146 PMCID: PMC4304130 DOI: 10.1186/2041-9139-5-25] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 07/10/2014] [Indexed: 01/09/2023] Open
Abstract
A particularly critical event in avian evolution was the transition from long- to short-tailed birds. Primitive bird tails underwent significant alteration, most notably reduction of the number of caudal vertebrae and fusion of the distal caudal vertebrae into an ossified pygostyle. These changes, among others, occurred over a very short evolutionary interval, which brings into focus the underlying mechanisms behind those changes. Despite the wealth of studies delving into avian evolution, virtually nothing is understood about the genetic and developmental events responsible for the emergence of short, fused tails. In this review, we summarize the current understanding of the signaling pathways and morphological events that contribute to tail extension and termination and examine how mutations affecting the genes that control these pathways might influence the evolution of the avian tail. To generate a list of candidate genes that may have been modulated in the transition to short-tailed birds, we analyzed a comprehensive set of mouse mutants. Interestingly, a prevalent pleiotropic effect of mutations that cause fused caudal vertebral bodies (as in the pygostyles of birds) is tail truncation. We identified 23 mutations in this class, and these were primarily restricted to genes involved in axial extension. At least half of the mutations that cause short, fused tails lie in the Notch/Wnt pathway of somite boundary formation or differentiation, leading to changes in somite number or size. Several of the mutations also cause additional bone fusions in the trunk skeleton, reminiscent of those observed in primitive and modern birds. All of our findings were correlated to the fossil record. An open question is whether the relatively sudden appearance of short-tailed birds in the fossil record could be accounted for, at least in part, by the pleiotropic effects generated by a relatively small number of mutational events.
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Affiliation(s)
- Dana J Rashid
- Museum of the Rockies, Montana State University, 600 West Kagy Blvd, Bozeman, MT 59717, USA
| | - Susan C Chapman
- Department of Biological Sciences, Clemson University, 340 Long Hall, Clemson, SC 29634, USA
| | - Hans Ce Larsson
- Redpath Museum, McGill University, 859 Sherbrooke Street W., Montreal, Quebec H3A 0C4, Canada
| | - Chris L Organ
- Museum of the Rockies, Montana State University, 600 West Kagy Blvd, Bozeman, MT 59717, USA ; Department of Earth Sciences, Montana State University, 226 Traphagen Hall, Bozeman, MT 59717, USA
| | - Anne-Gaelle Bebin
- Museum of the Rockies, Montana State University, 600 West Kagy Blvd, Bozeman, MT 59717, USA ; Current address: Vaccine and Gene Therapy FL, 9801 Discovery Way, Port Lucie, FL 34987, USA
| | - Christa S Merzdorf
- Department of Cell Biology & Neuroscience, Montana State University, 513 Leon Johnson Hall, Bozeman, MT 59717, USA
| | - Roger Bradley
- Department of Cell Biology & Neuroscience, Montana State University, 513 Leon Johnson Hall, Bozeman, MT 59717, USA
| | - John R Horner
- Museum of the Rockies, Montana State University, 600 West Kagy Blvd, Bozeman, MT 59717, USA
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Saint-Jeannet JP, Moody SA. Establishing the pre-placodal region and breaking it into placodes with distinct identities. Dev Biol 2014; 389:13-27. [PMID: 24576539 DOI: 10.1016/j.ydbio.2014.02.011] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 02/13/2014] [Accepted: 02/14/2014] [Indexed: 11/17/2022]
Abstract
Specialized sensory organs in the vertebrate head originate from thickenings in the embryonic ectoderm called cranial sensory placodes. These placodes, as well as the neural crest, arise from a zone of ectoderm that borders the neural plate. This zone separates into a precursor field for the neural crest that lies adjacent to the neural plate, and a precursor field for the placodes, called the pre-placodal region (PPR), that lies lateral to the neural crest. The neural crest domain and the PPR are established in response to signaling events mediated by BMPs, FGFs and Wnts, which differentially activate transcription factors in these territories. In the PPR, members of the Six and Eya families, act in part to repress neural crest specific transcription factors, thus solidifying a placode developmental program. Subsequently, in response to environmental cues the PPR is further subdivided into placodal territories with distinct characteristics, each expressing a specific repertoire of transcription factors that provide the necessary information for their progression to mature sensory organs. In this review we summarize recent advances in the characterization of the signaling molecules and transcriptional effectors that regulate PPR specification and its subdivision into placodal domains with distinct identities.
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Affiliation(s)
- Jean-Pierre Saint-Jeannet
- Department of Basic Science and Craniofacial Biology, New York University, College of Dentistry, 345 East 24th Street, New York City, NY 10010, USA.
| | - Sally A Moody
- Department of Anatomy and Regenerative Biology, The George Washington University, School of Medicine and Health Sciences, 2300 I (eye) Street, NW, Washington, DC 20037, USA.
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25
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Schlosser G, Patthey C, Shimeld SM. The evolutionary history of vertebrate cranial placodes II. Evolution of ectodermal patterning. Dev Biol 2014; 389:98-119. [PMID: 24491817 DOI: 10.1016/j.ydbio.2014.01.019] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 01/21/2014] [Accepted: 01/24/2014] [Indexed: 12/12/2022]
Abstract
Cranial placodes are evolutionary innovations of vertebrates. However, they most likely evolved by redeployment, rewiring and diversification of preexisting cell types and patterning mechanisms. In the second part of this review we compare vertebrates with other animal groups to elucidate the evolutionary history of ectodermal patterning. We show that several transcription factors have ancient bilaterian roles in dorsoventral and anteroposterior regionalisation of the ectoderm. Evidence from amphioxus suggests that ancestral chordates then concentrated neurosecretory cells in the anteriormost non-neural ectoderm. This anterior proto-placodal domain subsequently gave rise to the oral siphon primordia in tunicates (with neurosecretory cells being lost) and anterior (adenohypophyseal, olfactory, and lens) placodes of vertebrates. Likewise, tunicate atrial siphon primordia and posterior (otic, lateral line, and epibranchial) placodes of vertebrates probably evolved from a posterior proto-placodal region in the tunicate-vertebrate ancestor. Since both siphon primordia in tunicates give rise to sparse populations of sensory cells, both proto-placodal domains probably also gave rise to some sensory receptors in the tunicate-vertebrate ancestor. However, proper cranial placodes, which give rise to high density arrays of specialised sensory receptors and neurons, evolved from these domains only in the vertebrate lineage. We propose that this may have involved rewiring of the regulatory network upstream and downstream of Six1/2 and Six4/5 transcription factors and their Eya family cofactors. These proteins, which play ancient roles in neuronal differentiation were first recruited to the dorsal non-neural ectoderm in the tunicate-vertebrate ancestor but subsequently probably acquired new target genes in the vertebrate lineage, allowing them to adopt new functions in regulating proliferation and patterning of neuronal progenitors.
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Affiliation(s)
- Gerhard Schlosser
- Department of Zoology, School of Natural Sciences & Regenerative Medicine Institute (REMEDI), National University of Ireland, University Road, Galway, Ireland.
| | - Cedric Patthey
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
| | - Sebastian M Shimeld
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
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26
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Fernández JP, Agüero TH, Vega López GA, Marranzino G, Cerrizuela S, Aybar MJ. Developmental expression and role of Kinesin Eg5 duringXenopus laevisembryogenesis. Dev Dyn 2013; 243:527-40. [DOI: 10.1002/dvdy.24094] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 10/29/2013] [Accepted: 11/01/2013] [Indexed: 01/28/2023] Open
Affiliation(s)
- Juan P. Fernández
- INSIBIO, CONICET; Universidad Nacional de Tucumán; Tucumán Argentina
| | - Tristán H. Agüero
- INSIBIO, CONICET; Universidad Nacional de Tucumán; Tucumán Argentina
| | | | | | | | - Manuel J. Aybar
- INSIBIO, CONICET; Universidad Nacional de Tucumán; Tucumán Argentina
- Instituto de Biología “Dr. Francisco D. Barbieri,”; Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán; Tucumán Argentina
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27
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Setting appropriate boundaries: fate, patterning and competence at the neural plate border. Dev Biol 2013; 389:2-12. [PMID: 24321819 DOI: 10.1016/j.ydbio.2013.11.027] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 11/26/2013] [Accepted: 11/27/2013] [Indexed: 11/20/2022]
Abstract
The neural crest and craniofacial placodes are two distinct progenitor populations that arise at the border of the vertebrate neural plate. This border region develops through a series of inductive interactions that begins before gastrulation and progressively divide embryonic ectoderm into neural and non-neural regions, followed by the emergence of neural crest and placodal progenitors. In this review, we describe how a limited repertoire of inductive signals-principally FGFs, Wnts and BMPs-set up domains of transcription factors in the border region which establish these progenitor territories by both cross-inhibitory and cross-autoregulatory interactions. The gradual assembly of different cohorts of transcription factors that results from these interactions is one mechanism to provide the competence to respond to inductive signals in different ways, ultimately generating the neural crest and cranial placodes.
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28
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Reichert S, Randall RA, Hill CS. A BMP regulatory network controls ectodermal cell fate decisions at the neural plate border. Development 2013; 140:4435-44. [PMID: 24089471 DOI: 10.1242/dev.098707] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
During ectodermal patterning the neural crest and preplacodal ectoderm are specified in adjacent domains at the neural plate border. BMP signalling is required for specification of both tissues, but how it is spatially and temporally regulated to achieve this is not understood. Here, using a transgenic zebrafish BMP reporter line in conjunction with double-fluorescent in situ hybridisation, we show that, at the beginning of neurulation, the ventral-to-dorsal gradient of BMP activity evolves into two distinct domains at the neural plate border: one coinciding with the neural crest and the other abutting the epidermis. In between is a region devoid of BMP activity, which is specified as the preplacodal ectoderm. We identify the ligands required for these domains of BMP activity. We show that the BMP-interacting protein Crossveinless 2 is expressed in the BMP activity domains and is under the control of BMP signalling. We establish that Crossveinless 2 functions at this time in a positive-feedback loop to locally enhance BMP activity, and show that it is required for neural crest fate. We further demonstrate that the Distal-less transcription factors Dlx3b and Dlx4b, which are expressed in the preplacodal ectoderm, are required for the expression of a cell-autonomous BMP inhibitor, Bambi-b, which can explain the specific absence of BMP activity in the preplacodal ectoderm. Taken together, our data define a BMP regulatory network that controls cell fate decisions at the neural plate border.
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Affiliation(s)
- Sabine Reichert
- Laboratory of Developmental Signalling, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
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29
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Differential BMP signaling controls formation and differentiation of multipotent preplacodal ectoderm progenitors from human embryonic stem cells. Dev Biol 2013; 379:208-20. [PMID: 23643939 DOI: 10.1016/j.ydbio.2013.04.023] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 04/05/2013] [Accepted: 04/22/2013] [Indexed: 01/08/2023]
Abstract
Sensory and endoneurocrine tissues as diverse as the lens, the olfactory epithelium, the inner ear, the cranial sensory ganglia, and the anterior pituitary arise from a common pool of progenitors in the preplacodal ectoderm (PPE). Around late gastrulation, the PPE forms at the border surrounding the anterior neural plate, and expresses a unique set of evolutionarily conserved transcription regulators including Six1, Eya 1 and Eya2. Here, we describe the first report to generate and characterize the SIX1(+) PPE cells from human embryonic stem (ES) cells by adherent differentiation. Before forming PPE cells, differentiating cultures first expressed the non-neural ectoderm specific transcriptional factors TFAP2A, GATA2, GATA3, DLX3, and DLX5, which are crucial in establishing the PPE competence. We demonstrated that bone morphogenetic protein (BMP) activity plays a transient but essential role in inducing expression of these PPE competence factors and eventually the PPE cells. Interestingly, we found that attenuating BMP signaling after establishing the competence state induces anterior placode precursors. By manipulating BMP and hedgehog signaling pathways, we further differentiate these precursors into restricted lineages including the lens placode and the oral ectoderm (pituitary precursor) cells. Finally, we also show that sensory neurons can be generated from human PPE cells, demonstrating the multipotency of the human ES-derived PPE cells.
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30
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Bielen H, Houart C. BMP signaling protects telencephalic fate by repressing eye identity and its Cxcr4-dependent morphogenesis. Dev Cell 2013; 23:812-22. [PMID: 23079599 DOI: 10.1016/j.devcel.2012.09.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 08/08/2012] [Accepted: 09/07/2012] [Indexed: 12/22/2022]
Abstract
Depletion of Wnt signaling is a major requirement for the induction of the anterior prosencephalon. However, the molecular events driving the differential regionalization of this area into eye-field and telencephalon fates are still unknown. Here we show that the BMP pathway is active in the anterior neural ectoderm during late blastula to early gastrula stage in zebrafish. Bmp2b mutants and mosaic loss-of-function experiments reveal that BMP acts as a repressor of eye-field fate through inhibition of its key transcription factor Rx3, thereby protecting the future telencephalon from acquiring eye identity. This BMP-driven mechanism initiates the establishment of the telencephalon prior to the involvement of Wnt antagonists from the anterior neural border. Furthermore, we demonstrate that Rx3 and BMP are respectively required to maintain and restrict the chemokine receptor cxcr4a, which in turn contributes to the morphogenetic separation of eye-field and telencephalic cells during early neurulation.
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Affiliation(s)
- Holger Bielen
- Medical Research Council Centre for Developmental Neurobiology, King's College London, London SE1 1UL, UK
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31
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Espina J, Feijóo CG, Solís C, Glavic A. csrnp1a is necessary for the development of primitive hematopoiesis progenitors in zebrafish. PLoS One 2013; 8:e53858. [PMID: 23326522 PMCID: PMC3541188 DOI: 10.1371/journal.pone.0053858] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 12/04/2012] [Indexed: 11/19/2022] Open
Abstract
The CSRNP (cystein-serine-rich nuclear protein) transcription factors are conserved from Drosophila to human. Functional studies in mice, through knockout for each of their paralogs, have resulted insufficient to elucidate the function of this family of proteins in vertebrate development. Previously, we described the function of the zebrafish ortholog, Csnrp1/Axud1, showing its essential role in the survival and proliferation of cephalic progenitors. To extend our understanding of this family, we have studied the function of its paralog csrnp1a. Our results show that csrnp1a is expressed from 0 hpf, until larval stages, particularly in cephalic territories and in the intermediate cell mass (ICM). Using morpholinos in wild type and transgenic lines we observed that Csrnp1a knockdown generates a mild reduction in head size and a depletion of blood cells in circulation. This was combined with in situ hybridizations to analyze the expression of different mesodermal and primitive hematopoiesis markers. Morphant embryos have impaired blood formation without disruption of mesoderm specification, angiogenesis or heart development. The reduction of circulating blood cells occurs at the hematopoietic progenitor level, affecting both the erythroid and myeloid lineages. In addition, cell proliferation was also altered in hematopoietic anterior sites, specifically in spi1 expression domain. These and previous observations suggest an important role of Csnrps transcription factors in progenitor biology, both in the neural and hematopoietic linages.
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Affiliation(s)
- Jaime Espina
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
- Departamento de Ciencia Biologicas, Facultad de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile
| | - Carmen G. Feijóo
- Departamento de Ciencia Biologicas, Facultad de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile
| | - Camila Solís
- Departamento de Ciencia Biologicas, Facultad de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile
| | - Alvaro Glavic
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
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32
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Abstract
The vertebrate oral region represents a key interface between outer and inner environments, and its structural and functional design is among the limiting factors for survival of its owners. Both formation of the respective oral opening (primary mouth) and establishment of the food-processing apparatus (secondary mouth) require interplay between several embryonic tissues and complex embryonic rearrangements. Although many aspects of the secondary mouth formation, including development of the jaws, teeth or taste buds, are known in considerable detail, general knowledge about primary mouth formation is regrettably low. In this paper, primary mouth formation is reviewed from a comparative point of view in order to reveal its underestimated morphogenetic diversity among, and also within, particular vertebrate clades. In general, three main developmental modes were identified. The most common is characterized by primary mouth formation via a deeply invaginated ectodermal stomodeum and subsequent rupture of the bilaminar oral membrane. However, in salamander, lungfish and also in some frog species, the mouth develops alternatively via stomodeal collar formation contributed both by the ecto- and endoderm. In ray-finned fishes, on the other hand, the mouth forms via an ectoderm wedge and later horizontal detachment of the initially compressed oral epithelia with probably a mixed germ-layer derivation. A very intriguing situation can be seen in agnathan fishes: whereas lampreys develop their primary mouth in a manner similar to the most common gnathostome pattern, hagfishes seem to undergo a unique oropharyngeal morphogenesis when compared with other vertebrates. In discussing the early formative embryonic correlates of primary mouth formation likely to be responsible for evolutionary-developmental modifications of this area, we stress an essential role of four factors: first, positioning and amount of yolk tissue; closely related to, second, endoderm formation during gastrulation, which initiates the process and constrains possible evolutionary changes within this area; third, incipient structure of the stomodeal primordium at the anterior neural plate border, where the ectoderm component of the prospective primary mouth is formed; and fourth, the prime role of Pitx genes for establishment and later morphogenesis of oral region both in vertebrates and non-vertebrate chordates.
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Affiliation(s)
- Vladimír Soukup
- Department of Zoology, Charles University in Prague, Prague, Czech Republic
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33
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Abstract
Despite its complexity in the adult, during development the inner ear arises from a simple epithelium, the otic placode. Placode specification is a multistep process that involves the integration of various signalling pathways and downstream transcription factors in time and space. Here we review the molecular events that successively commit multipotent ectodermal precursors to the otic lineage. The first step in this hierarchy is the specification of sensory progenitor cells, which can contribute to all sensory placodes, followed by the induction of a common otic-epibranchial field and finally the establishment the otic territory. In recent years, some of the molecular components that control this process have been identified, and begin to reveal complex interactions. Future studies will need to unravel how this information is integrated and encoded in the genome. This will form the blueprint for stem cell differentiation towards otic fates and generate a predictive gene regulatory network that models the earliest steps of otic specification.
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Affiliation(s)
- Jingchen Chen
- Department of Craniofacial Development and Stem Cell Biology, King's College London, Guy's Tower Wing, Floor 27, London SE1 9RT, UK
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34
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A gene network that coordinates preplacodal competence and neural crest specification in zebrafish. Dev Biol 2012; 373:107-17. [PMID: 23078916 DOI: 10.1016/j.ydbio.2012.10.012] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2012] [Revised: 09/23/2012] [Accepted: 10/09/2012] [Indexed: 11/20/2022]
Abstract
Preplacodal ectoderm (PPE) and neural crest (NC) are specified at the interface of neural and nonneural ectoderm and together contribute to the peripheral nervous system in all vertebrates. Bmp activates early steps for both fates during late blastula stage. Low Bmp activates expression of transcription factors Tfap2a and Tfap2c in the lateral neural plate, thereby specifying neural crest fate. Elevated Bmp establishes preplacodal competence throughout the ventral ectoderm by coinducing Tfap2a, Tfap2c, Foxi1 and Gata3. PPE specification occurs later at the end of gastrulation and requires complete attenuation of Bmp, yet expression of PPE competence factors continues well past gastrulation. Here we show that competence factors positively regulate each other's expression during gastrulation, forming a self-sustaining network that operates independently of Bmp. Misexpression of Tfap2a in embryos blocked for Bmp from late blastula stage can restore development of both PPE and NC. However, Tfap2a alone is not sufficient to activate any other competence factors nor does it rescue individual placodes. On the other hand, misexpression of any two competence factors in Bmp-blocked embryos can activate the entire transcription factor network and support the development of NC, PPE and some individual placodes. We also show that while these factors are partially redundant with respect to PPE specification, they later provide non-redundant functions needed for development of specific placodes. Thus, we have identified a gene regulatory network that coordinates development of NC, PPE and individual placodes in zebrafish.
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35
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Parlier D, Moers V, Van Campenhout C, Preillon J, Leclère L, Saulnier A, Sirakov M, Busengdal H, Kricha S, Marine JC, Rentzsch F, Bellefroid EJ. The Xenopus doublesex-related gene Dmrt5 is required for olfactory placode neurogenesis. Dev Biol 2012; 373:39-52. [PMID: 23064029 DOI: 10.1016/j.ydbio.2012.10.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 09/16/2012] [Accepted: 10/03/2012] [Indexed: 11/17/2022]
Abstract
The Dmrt (doublesex and mab-3 related transcription factor) genes encode a large family of evolutionarily conserved transcription factors whose function in sex specific differentiation has been well studied in all animal lineages. In vertebrates, their function is not restricted to the developing gonads. For example, Xenopus Dmrt4 is essential for neurogenesis in the olfactory system. Here we have isolated and characterized Xenopus Dmrt5 and found that it is coexpressed with Dmrt4 in the developing olfactory placodes. As Dmrt4, Dmrt5 is positively regulated in the ectoderm by neural inducers and negatively by proneural factors. Both Dmrt5 and Dmrt4 genes are also activated by the combined action of the transcription factor Otx2, broadly transcribed in the head ectoderm and of Notch signaling, activated in the anterior neural ridge. As for Dmrt4, knockdown of Dmrt5 impairs neurogenesis in the embryonic olfactory system and in neuralized animal caps. Conversely, its overexpression promotes neuronal differentiation in animal caps, a property that requires the conserved C-terminal DMA and DMB domains. We also found that the sea anenome Dmrt4/5 related gene NvDmrtb also induces neurogenesis in Xenopus animal caps and that conversely, its knockdown in Nematostella reduces elav-1 positive neurons. Together, our data identify Dmrt5 as a novel important regulator of neurogenesis whose function overlaps with that of Dmrt4 during Xenopus olfactory system development. They also suggest that Dmrt may have had a role in neurogenesis in the last common ancestor of cnidarians and bilaterians.
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Affiliation(s)
- Damien Parlier
- Laboratoire de Génétique du Développement, Université Libre de Bruxelles, Institut de Biologie et de Médecine Moléculaires (IBMM), rue des Profs. Jeener et Brachet 12, B-6041 Gosselies, Belgium
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36
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Grocott T, Tambalo M, Streit A. The peripheral sensory nervous system in the vertebrate head: a gene regulatory perspective. Dev Biol 2012; 370:3-23. [PMID: 22790010 DOI: 10.1016/j.ydbio.2012.06.028] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 06/28/2012] [Accepted: 06/29/2012] [Indexed: 02/06/2023]
Abstract
In the vertebrate head, crucial parts of the sense organs and sensory ganglia develop from special regions, the cranial placodes. Despite their cellular and functional diversity, they arise from a common field of multipotent progenitors and acquire distinct identity later under the influence of local signalling. Here we present the gene regulatory network that summarises our current understanding of how sensory cells are specified, how they become different from other ectodermal derivatives and how they begin to diversify to generate placodes with different identities. This analysis reveals how sequential activation of sets of transcription factors subdivides the ectoderm over time into smaller domains of progenitors for the central nervous system, neural crest, epidermis and sensory placodes. Within this hierarchy the timing of signalling and developmental history of each cell population is of critical importance to determine the ultimate outcome. A reoccurring theme is that local signals set up broad gene expression domains, which are further refined by mutual repression between different transcription factors. The Six and Eya network lies at the heart of sensory progenitor specification. In a positive feedback loop these factors perpetuate their own expression thus stabilising pre-placodal fate, while simultaneously repressing neural and neural crest specific factors. Downstream of the Six and Eya cassette, Pax genes in combination with other factors begin to impart regional identity to placode progenitors. While our review highlights the wealth of information available, it also points to the lack information on the cis-regulatory mechanisms that control placode specification and of how the repeated use of signalling input is integrated.
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Affiliation(s)
- Timothy Grocott
- Department of Craniofacial Development and Stem Cell Biology, King's College London, Guy's Tower Wing, Floor 27, London SE1 9RT, UK
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37
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Lleras-Forero L, Streit A. Development of the sensory nervous system in the vertebrate head: the importance of being on time. Curr Opin Genet Dev 2012; 22:315-22. [PMID: 22726669 DOI: 10.1016/j.gde.2012.05.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 03/30/2012] [Accepted: 05/15/2012] [Indexed: 12/18/2022]
Abstract
Sense organs and cranial sensory ganglia are functionally diverse, yet share a common developmental origin. They arise from a pool of multipotent progenitors and local signals gradually restrict their development potential to specify the inner ear, olfactory epithelium, lens and sensory neurons. This process requires the temporal integration of multiple signalling pathways, cross-repressive transcription factor interactions and tight coordination of cell fate specification and morphogenesis.
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Affiliation(s)
- Laura Lleras-Forero
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London SE1 9RT, UK
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38
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Steventon B, Mayor R. Early neural crest induction requires an initial inhibition of Wnt signals. Dev Biol 2012; 365:196-207. [PMID: 22394485 PMCID: PMC3657187 DOI: 10.1016/j.ydbio.2012.02.029] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 01/31/2012] [Accepted: 02/20/2012] [Indexed: 01/28/2023]
Abstract
Neural crest (NC) induction is a long process that continues through gastrula and neurula stages. In order to reveal additional stages of NC induction we performed a series of explants where different known inducing tissues were taken along with the prospective NC. Interestingly the dorso-lateral marginal zone (DLMZ) is only able to promote the expression of a subset of neural plate border (NPB) makers without the presence of specific NC markers. We then analysed the temporal requirement for BMP and Wnt signals for the NPB genes Hairy2a and Dlx5, compared to the expression of neural plate (NP) and NC genes. Although the NP is sensitive to BMP levels at early gastrula stages, Hairy2a/Dlx5 expression is unaffected. Later, the NP becomes insensitive to BMP levels at late gastrulation when NC markers require an inhibition. The NP requires an inhibition of Wnt signals prior to gastrulation, but becomes insensitive during early gastrula stages when Hairy2a/Dlx5 requires an inhibition of Wnt signalling. An increase in Wnt signalling is then important for the switch from NPB to NC at late gastrula stages. In addition to revealing an additional distinct signalling event in NC induction, this work emphasizes the importance of integrating both timing and levels of signalling activity during the patterning of complex tissues such as the vertebrate ectoderm.
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Affiliation(s)
| | - Roberto Mayor
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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39
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Abstract
During early vertebrate development, the embryonic ectoderm becomes subdivided into neural, neural plate border (border) and epidermal regions. The nervous system is derived from the neural and border domains which, respectively, give rise to the central and peripheral nervous systems. To better understand the functional nervous system we need to know how individual neurons are specified and connected. Our understanding of the early development of the peripheral nervous system has been lagging compared to knowledge regarding central nervous system and epidermal cell lineage decision. Recent advances have shown when and how the specification of border cells is initiated. One important insight is that border specification is already initiated at blastula stages, and can be molecularly and temporally distinguished from rostrocaudal regionalisation of the border. From findings in several species, it is clear that Wnt, Bone Morphogenetic Protein and Fibroblast Growth Factor signals play important roles during the specification and regionalisation of the border. In this review, we highlight the individual roles of these signals and compare models of border specification, including a new model that describes how temporal coordination and epistatic interactions of extracellular signals result in the specification and regionalisation of border cells.
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Affiliation(s)
- Cédric Patthey
- Umeå Centre for Molecular Medicine, Building 6M, 4th Floor, Umeå University, S-901 87 Umeå, Sweden
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40
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Liu C, Goswami M, Talley J, Chesser-Martinez PL, Lou CH, Sater AK. TAK1 promotes BMP4/Smad1 signaling via inhibition of erk MAPK: a new link in the FGF/BMP regulatory network. Differentiation 2012; 83:210-9. [PMID: 22387344 DOI: 10.1016/j.diff.2011.12.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 12/05/2011] [Accepted: 12/31/2011] [Indexed: 01/22/2023]
Abstract
FGFs and BMPs act in concert to regulate a wide range of processes in vertebrate development. In most cases, FGFs and BMPs have opposing effects, and specific developmental outcomes arise out of a balance between the two growth factors. We and others have previously demonstrated that signaling pathways activated by FGFs and BMPs interact via inhibitory crosstalk. Here we demonstrate a role for the BMP effector TGF-β Activated Kinase 1 (TAK1) in the maintenance of Smad1 activity in Xenopus embryos, via the inhibition of erk MAPK. Up- or downregulation of TAK1 levels produces an inverse alteration in the amount of activated erk MAPK. The inhibition of erk MAPK by TAK1 is mediated by p38 and a corresponding decrease in phosphorylation of MEK. TAK1 morphant embryos show a decrease in the nuclear accumulation of Smad1. Conversely, reduction of erk MAPK activity via overexpression of MAP Kinase Phosphatase1 (MKP1) leads to an increase in nuclear Smad1. Both TAK1 morphant ectoderm and ectoderm treated with FGF show a decrease in the expression of several Smad1-inducible genes. Neural-specific gene expression is inhibited in isolated ectoderm coexpressing noggin and TAK1, suggesting that TAK1 is sufficient to inhibit neural specification. Introduction of TAK1 morpholino oligonucleotide expands the expression of organizer genes, disrupts formation of the boundary between organizer and non-organizer mesoderm, and increases the spatial range of MAPK activation in response to localized FGF. Our results indicate that inhibitory interactions between FGF and BMP4 effector pathways increase the robustness of BMP signaling via a feed-forward mechanism.
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Affiliation(s)
- Chen Liu
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA
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Pieper M, Ahrens K, Rink E, Peter A, Schlosser G. Differential distribution of competence for panplacodal and neural crest induction to non-neural and neural ectoderm. Development 2012; 139:1175-87. [PMID: 22318231 DOI: 10.1242/dev.074468] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
It is still controversial whether cranial placodes and neural crest cells arise from a common precursor at the neural plate border or whether placodes arise from non-neural ectoderm and neural crest from neural ectoderm. Using tissue grafting in embryos of Xenopus laevis, we show here that the competence for induction of neural plate, neural plate border and neural crest markers is confined to neural ectoderm, whereas competence for induction of panplacodal markers is confined to non-neural ectoderm. This differential distribution of competence is established during gastrulation paralleling the dorsal restriction of neural competence. We further show that Dlx3 and GATA2 are required cell-autonomously for panplacodal and epidermal marker expression in the non-neural ectoderm, while ectopic expression of Dlx3 or GATA2 in the neural plate suppresses neural plate, border and crest markers. Overexpression of Dlx3 (but not GATA2) in the neural plate is sufficient to induce different non-neural markers in a signaling-dependent manner, with epidermal markers being induced in the presence, and panplacodal markers in the absence, of BMP signaling. Taken together, these findings demonstrate a non-neural versus neural origin of placodes and neural crest, respectively, strongly implicate Dlx3 in the regulation of non-neural competence, and show that GATA2 contributes to non-neural competence but is not sufficient to promote it ectopically.
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Affiliation(s)
- Mareike Pieper
- Brain Research Institute, University of Bremen, FB2, PO Box 330440, 28334 Bremen, Germany
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Park BY, Hong CS, Weaver JR, Rosocha EM, Saint-Jeannet JP. Xaml1/Runx1 is required for the specification of Rohon-Beard sensory neurons in Xenopus. Dev Biol 2011; 362:65-75. [PMID: 22173066 DOI: 10.1016/j.ydbio.2011.11.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 11/14/2011] [Accepted: 11/21/2011] [Indexed: 11/27/2022]
Abstract
Lower vertebrates develop a unique set of primary sensory neurons located in the dorsal spinal cord. These cells, known as Rohon-Beard (RB) sensory neurons, innervate the skin and mediate the response to touch during larval stages. Here we report the expression and function of the transcription factor Xaml1/Runx1 during RB sensory neurons formation. In Xenopus embryos Runx1 is specifically expressed in RB progenitors at the end of gastrulation. Runx1 expression is positively regulated by Fgf and canonical Wnt signaling and negatively regulated by Notch signaling, the same set of factors that control the development of other neural plate border cell types, i.e. the neural crest and cranial placodes. Embryos lacking Runx1 function fail to differentiate RB sensory neurons and lose the mechanosensory response to touch. At early stages Runx1 knockdown results in a RB progenitor-specific loss of expression of Pak3, a p21-activated kinase that promotes cell cycle withdrawal, and of N-tub, a neuronal-specific tubulin. Interestingly, the pro-neural gene Ngnr1, an upstream regulator of Pak3 and N-tub, is either unaffected or expanded in these embryos, suggesting the existence of two distinct regulatory pathways controlling sensory neuron formation in Xenopus. Consistent with this possibility Ngnr1 is not sufficient to activate Runx1 expression in the ectoderm. We propose that Runx1 function is critically required for the generation of RB sensory neurons, an activity reminiscent of that of Runx1 in the development of the mammalian dorsal root ganglion nociceptive sensory neurons.
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Affiliation(s)
- Byung-Yong Park
- Department of Anatomy, College of Veterinary Medicine, Chonbuk National University, Jeonju, Republic of Korea
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Integrin-α5 coordinates assembly of posterior cranial placodes in zebrafish and enhances Fgf-dependent regulation of otic/epibranchial cells. PLoS One 2011; 6:e27778. [PMID: 22164214 PMCID: PMC3229493 DOI: 10.1371/journal.pone.0027778] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 10/25/2011] [Indexed: 12/15/2022] Open
Abstract
Vertebrate sensory organs develop in part from cranial placodes, a series of ectodermal thickenings that coalesce from a common domain of preplacodal ectoderm. Mechanisms coordinating morphogenesis and differentiation of discrete placodes are still poorly understood. We have investigated whether placodal assembly in zebrafish requires Integrin- α5 (itga5), an extracellular matrix receptor initially expressed throughout the preplacodal ectoderm. Morpholino knockdown of itga5 had no detectable effect on anterior placodes (pituitary, nasal and lens), but posterior placodes developed abnormally, resulting in disorganization of trigeminal and epibranchial ganglia and reduction of the otic vesicle. Cell motion analysis in GFP-transgenic embryos showed that cell migration in itga5 morphants was highly erratic and unfocused, impairing convergence and blocking successive recruitment of new cells into these placodes. Further studies revealed genetic interactions between itga5 and Fgf signaling. First, itga5 morphants showed changes in gene expression mimicking modest reduction in Fgf signaling. Second, itga5 morphants showed elevated apoptosis in the otic/epibranchial domain, which was rescued by misexpression of Fgf8. Third, knockdown of the Fgf effector erm had no effect by itself but strongly enhanced defects in itga5 morphants. Finally, proper regulation of itga5 requires dlx3b/4b and pax8, which are themselves regulated by Fgf. These findings support a model in which itga5 coordinates cell migration into posterior placodes and augments Fgf signaling required for patterning of these tissues and cell survival in otic/epibranchial placodes.
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Origin and segregation of cranial placodes in Xenopus laevis. Dev Biol 2011; 360:257-75. [PMID: 21989028 DOI: 10.1016/j.ydbio.2011.09.024] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2011] [Revised: 08/31/2011] [Accepted: 09/01/2011] [Indexed: 11/23/2022]
Abstract
Cranial placodes are local thickenings of the vertebrate head ectoderm that contribute to the paired sense organs (olfactory epithelium, lens, inner ear, lateral line), cranial ganglia and the adenohypophysis. Here we use tissue grafting and dye injections to generated fate maps of the dorsal cranial part of the non-neural ectoderm for Xenopus embryos between neural plate and early tailbud stages. We show that all placodes arise from a crescent-shaped area located around the anterior neural plate, the pre-placodal ectoderm. In agreement with proposed roles of Six1 and Pax genes in the specification of a panplacodal primordium and different placodal areas, respectively, we show that Six1 is expressed uniformly throughout most of the pre-placodal ectoderm, while Pax6, Pax3, Pax8 and Pax2 each are confined to specific subregions encompassing the precursors of different subsets of placodes. However, the precursors of the vagal epibranchial and posterior lateral line placodes, which arise from the posteriormost pre-placodal ectoderm, upregulate Six1 and Pax8/Pax2 only at tailbud stages. Whereas our fate map suggests that regions of origin for different placodes overlap extensively with each other and with other ectodermal fates at neural plate stages, analysis of co-labeled placodes reveals that the actual degree of overlap is much smaller. Time lapse imaging of the pre-placodal ectoderm at single cell resolution demonstrates that no directed, large-scale cell rearrangements occur, when the pre-placodal region segregates into distinct placodes at subsequent stages. Our results indicate that individuation of placodes from the pre-placodal ectoderm does not involve large-scale cell sorting in Xenopus.
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Neuronal loss and abnormal BMP/Smad signaling in the myenteric plexus of diabetic rats. Auton Neurosci 2011; 164:51-61. [PMID: 21737358 DOI: 10.1016/j.autneu.2011.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Revised: 06/08/2011] [Accepted: 06/09/2011] [Indexed: 12/25/2022]
Abstract
Bone morphogenetic proteins (BMPs) are critical molecules during gut morphogenesis. However, little is known about their participation in the homeostasis of adult gut and their possible role in diseases. Gastrointestinal complications occur during diabetes with loss of enteric neurons. In this study, we investigated the possible involvement of BMPs signaling pathway in diabetic enteric neuropathy in an experimental model of diabetes in rats. The expression of BMPs, BMPs receptors and intracellular Smad effectors were assessed in control and diabetic smooth muscle layer of jejunum by immunofluorescence, Western blot and RT-PCR methods. Myenteric neurons and glial cells were measured by immunofluorescence using specific markers. In addition, cell apoptosis was evaluated by means of direct and indirect techniques. We demonstrated that diabetic ganglia displayed a significant decrease in ganglion size due to enhanced apoptosis and loss of peripherin. A decrease in glial fibrillary acidic protein (GFAP protein) was also observed in enteric glial cells. BMP-2 was down-regulated in the myenteric plexus of diabetic rats at 3 and 9weeks. A loss of enteric neurons by apoptosis was correlated with an ectopic BMP-4, increased BMPR-Ia and nuclear p-Smad1 expression in the myenteric plexus. Insulin-treatment prevented the intestinal alterations observed. These findings suggest that diabetes is associated with an abnormal BMP/Smad signaling expression in the myenteric ganglia that affects the homeostasis of the enteric plexus.
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Kwon HJ, Bhat N, Sweet EM, Cornell RA, Riley BB. Identification of early requirements for preplacodal ectoderm and sensory organ development. PLoS Genet 2010; 6:e1001133. [PMID: 20885782 PMCID: PMC2944784 DOI: 10.1371/journal.pgen.1001133] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Accepted: 08/22/2010] [Indexed: 11/25/2022] Open
Abstract
Preplacodal ectoderm arises near the end of gastrulation as a narrow band of cells surrounding the anterior neural plate. This domain later resolves into discrete cranial placodes that, together with neural crest, produce paired sensory structures of the head. Unlike the better-characterized neural crest, little is known about early regulation of preplacodal development. Classical models of ectodermal patterning posit that preplacodal identity is specified by readout of a discrete level of Bmp signaling along a DV gradient. More recent studies indicate that Bmp-antagonists are critical for promoting preplacodal development. However, it is unclear whether Bmp-antagonists establish the proper level of Bmp signaling within a morphogen gradient or, alternatively, block Bmp altogether. To begin addressing these issues, we treated zebrafish embryos with a pharmacological inhibitor of Bmp, sometimes combined with heat shock-induction of Chordin and dominant-negative Bmp receptor, to fully block Bmp signaling at various developmental stages. We find that preplacodal development occurs in two phases with opposing Bmp requirements. Initially, Bmp is required before gastrulation to co-induce four transcription factors, Tfap2a, Tfap2c, Foxi1, and Gata3, which establish preplacodal competence throughout the nonneural ectoderm. Subsequently, Bmp must be fully blocked in late gastrulation by dorsally expressed Bmp-antagonists, together with dorsally expressed Fgf and Pdgf, to specify preplacodal identity within competent cells abutting the neural plate. Localized ventral misexpression of Fgf8 and Chordin can activate ectopic preplacodal development anywhere within the zone of competence, whereas dorsal misexpression of one or more competence factors can activate ectopic preplacodal development in the neural plate. Conversely, morpholino-knockdown of competence factors specifically ablates preplacodal development. Our work supports a relatively simple two-step model that traces regulation of preplacodal development to late blastula stage, resolves two distinct phases of Bmp dependence, and identifies the main factors required for preplacodal competence and specification. Cranial placodes, which produce sensory structures in the head, arise from a contiguous band of preplacodal ectoderm surrounding the anterior neural plate during gastrulation. Little is known about early regulation of preplacodal ectoderm, but modulation of signaling through Bone Morphogenetic Protein (Bmp) is clearly involved. Recent studies show that dorsally expressed Bmp-antagonists help establish preplacodal ectoderm, but it is not clear whether antagonists titrate Bmp to a discrete low level that actively induces preplacodal fate or, alternatively, whether Bmp must be fully blocked to permit preplacodal development. We show that in zebrafish preplacodal development occurs in distinct phases with differing Bmp requirements. Initially, Bmp is required before gastrulation to render all ventral ectoderm competent to form preplacodal tissue. We further show that four transcription factors, Foxi1, Gata3, Tfap2a, and Tfap2c, specifically mediate preplacodal competence. Once induced, these factors no longer require Bmp. Thereafter, Bmp must be fully blocked by dorsally expressed Bmp-antagonists to permit preplacodal development. In addition, dorsally expressed Fgf and/or Pdgf are also required, activating preplacodal development in competent cells abutting the neural plate. Thus, we have resolved the role of Bmp and traced the regulation of preplacodal development to pre-gastrula stage.
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Affiliation(s)
- Hye-Joo Kwon
- Biology Department, Texas A&M University, College Station, Texas, United States of America
| | - Neha Bhat
- Biology Department, Texas A&M University, College Station, Texas, United States of America
| | - Elly M. Sweet
- Biology Department, Texas A&M University, College Station, Texas, United States of America
| | - Robert A. Cornell
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Bruce B. Riley
- Biology Department, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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Sato S, Ikeda K, Shioi G, Ochi H, Ogino H, Yajima H, Kawakami K. Conserved expression of mouse Six1 in the pre-placodal region (PPR) and identification of an enhancer for the rostral PPR. Dev Biol 2010; 344:158-71. [PMID: 20471971 DOI: 10.1016/j.ydbio.2010.04.029] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 04/24/2010] [Accepted: 04/26/2010] [Indexed: 10/19/2022]
Abstract
All cranial sensory organs and sensory neurons of vertebrates develop from cranial placodes. In chick, amphibians and zebrafish, all placodes originate from a common precursor domain, the pre-placodal region (PPR), marked by the expression of Six1/4 and Eya1/2. However, the PPR has never been described in mammals and the mechanism involved in the formation of PPR is poorly defined. Here, we report the expression of Six1 in the horseshoe-shaped mouse ectoderm surrounding the anterior neural plate in a pattern broadly similar to that of non-mammalian vertebrates. To elucidate the identity of Six1-positive mouse ectoderm, we searched for enhancers responsible for Six1 expression by in vivo enhancer assays. One conserved non-coding sequence, Six1-14, showed specific enhancer activity in the rostral PPR of chick and Xenopus and in the mouse ectoderm. These results strongly suggest the presence of PPR in mouse and that it is conserved in vertebrates. Moreover, we show the importance of the homeodomain protein-binding sites of Six1-14, the Six1 rostral PPR enhancer, for enhancer activity, and that Dlx5, Msx1 and Pax7 are candidate binding factors that regulate the level and area of Six1 expression, and thereby the location of the PPR. Our findings provide critical information and tools to elucidate the molecular mechanism of early sensory development and have implications for the development of sensory precursor/stem cells.
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Affiliation(s)
- Shigeru Sato
- Division of Biology, Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan.
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Schlosser G. Making senses development of vertebrate cranial placodes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 283:129-234. [PMID: 20801420 DOI: 10.1016/s1937-6448(10)83004-7] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Cranial placodes (which include the adenohypophyseal, olfactory, lens, otic, lateral line, profundal/trigeminal, and epibranchial placodes) give rise to many sense organs and ganglia of the vertebrate head. Recent evidence suggests that all cranial placodes may be developmentally related structures, which originate from a common panplacodal primordium at neural plate stages and use similar regulatory mechanisms to control developmental processes shared between different placodes such as neurogenesis and morphogenetic movements. After providing a brief overview of placodal diversity, the present review summarizes current evidence for the existence of a panplacodal primordium and discusses the central role of transcription factors Six1 and Eya1 in the regulation of processes shared between different placodes. Upstream signaling events and transcription factors involved in early embryonic induction and specification of the panplacodal primordium are discussed next. I then review how individual placodes arise from the panplacodal primordium and present a model of multistep placode induction. Finally, I briefly summarize recent advances concerning how placodal neurons and sensory cells are specified, and how morphogenesis of placodes (including delamination and migration of placode-derived cells and invagination) is controlled.
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Affiliation(s)
- Gerhard Schlosser
- Zoology, School of Natural Sciences & Martin Ryan Institute, National University of Ireland, Galway, Ireland
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Kwon HJ, Riley BB. Mesendodermal signals required for otic induction: Bmp-antagonists cooperate with Fgf and can facilitate formation of ectopic otic tissue. Dev Dyn 2009; 238:1582-94. [PMID: 19418450 PMCID: PMC2835543 DOI: 10.1002/dvdy.21955] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Induction of otic placodes requires Fgf from surrounding tissues. We tested the hypothesis that mesendodermally derived Bmp-antagonists Chordin, Follistatin-a, and Crossveinless-2 cooperate in this process. Injecting morpholinos for all three genes, or treatment with the Nodal inhibitor SB431542 to block mesoderm-formation, reduces otic induction and strongly enhances the effects of disrupting fgf3 or fgf8. In contrast, using a lower dose of SB431542, combined with partial loss of Fgf, causes a dramatic medial expansion of otic tissue and formation of a single, large otic vesicle spanning the width of the hindbrain. Under these conditions, paraxial cephalic mesoderm forms ectopically at the midline, migrates into the head, and later transfates to form otic tissue beneath the hindbrain. Blocking expression of Bmp-antagonists blocks formation of medial otic tissue. These data show the importance of mesendodermal Bmp-antagonists for otic induction and that paraxial cephalic mesendoderm can facilitate its own otic differentiation under certain circumstances. Developmental Dynamics 238:1582-1594, 2009. (c) 2009 Wiley-Liss, Inc.
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Affiliation(s)
- Hye-Joo Kwon
- Biology Department, Texas A&M University, College Station, Texas, USA
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