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Datta S, Cao W, Skillman M, Wu M. Hypoplastic Left Heart Syndrome: Signaling & Molecular Perspectives, and the Road Ahead. Int J Mol Sci 2023; 24:15249. [PMID: 37894928 PMCID: PMC10607600 DOI: 10.3390/ijms242015249] [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: 09/13/2023] [Revised: 10/07/2023] [Accepted: 10/12/2023] [Indexed: 10/29/2023] Open
Abstract
Hypoplastic left heart syndrome (HLHS) is a lethal congenital heart disease (CHD) affecting 8-25 per 100,000 neonates globally. Clinical interventions, primarily surgical, have improved the life expectancy of the affected subjects substantially over the years. However, the etiological basis of HLHS remains fundamentally unclear to this day. Based upon the existing paradigm of studies, HLHS exhibits a multifactorial mode of etiology mediated by a complicated course of genetic and signaling cascade. This review presents a detailed outline of the HLHS phenotype, the prenatal and postnatal risks, and the signaling and molecular mechanisms driving HLHS pathogenesis. The review discusses the potential limitations and future perspectives of studies that can be undertaken to address the existing scientific gap. Mechanistic studies to explain HLHS etiology will potentially elucidate novel druggable targets and empower the development of therapeutic regimens against HLHS in the future.
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Affiliation(s)
| | | | | | - Mingfu Wu
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, USA; (S.D.); (W.C.); (M.S.)
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2
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Gaps and barriers: Gap junctions as a channel of communication between the soma and the germline. Semin Cell Dev Biol 2019; 97:167-171. [PMID: 31558347 DOI: 10.1016/j.semcdb.2019.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 08/29/2019] [Accepted: 09/04/2019] [Indexed: 12/20/2022]
Abstract
Gap junctions, expressed in most tissues of the body, allow for the cytoplasmic coupling of adjacent cells and promote tissue cooperation. Gap junctions connect also the soma and the germline in many animals, and transmit somatic signals that are crucial for germline maturation and integrity. In this review, we examine the involvement of gap junctions in the relay of information between the soma and the germline, and ask whether such communication could have consequences for the progeny. While the influence of parental experiences on descendants is of great interest, the possibility that gap junctions participate in the transmission of information across generations is largely unexplored.
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3
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Usui Y, Aramaki T, Kondo S, Watanabe M. The minimal gap-junction network among melanophores and xanthophores required for stripe-pattern formation in zebrafish. Development 2019; 146:dev.181065. [DOI: 10.1242/dev.181065] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 10/24/2019] [Indexed: 12/16/2022]
Abstract
Connexin39.4 (Cx39.4) and Connexin41.8 (Cx41.8), two gap-junction proteins expressed in both melanophores and xanthophores, are critical for the intercellular communication among pigment cells that is necessary for generating the stripe pigment pattern of zebrafish. We previously characterized the gap-junction properties of Cx39.4 and Cx41.8, but how these proteins contribute to stripe formation remains unclear; this is because distinct types of connexins potentially form heteromeric gap junctions, which precludes accurate elucidation of individual connexin functions in vivo. Here, by arranging Cx39.4 and Cx41.8 expression in pigment cells, we identified the simplest gap-junction network required for stripe generation: Cx39.4 expression in melanophores is required but expression in xanthophores is not necessary for stripe patterning, whereas Cx41.8 expression in xanthophores is sufficient for the patterning, and Cx41.8 expression in melanophores might stabilize the stripes. Moreover, patch-clamp recordings revealed that Cx39.4 gap junctions exhibit spermidine-dependent rectification property. Our results suggest that Cx39.4 facilitates the critical cell-cell interactions between melanophores and xanthophores that mediate a unidirectional activation-signal transfer from xanthophores to melanophores, which is essential for melanophore survival.
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Affiliation(s)
- Yuu Usui
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Toshihiro Aramaki
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shigeru Kondo
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
- CREST, Japan Science and Technology Agency, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Masakatsu Watanabe
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
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4
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Bioelectrical coupling in multicellular domains regulated by gap junctions: A conceptual approach. Bioelectrochemistry 2018; 123:45-61. [DOI: 10.1016/j.bioelechem.2018.04.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/13/2018] [Accepted: 04/17/2018] [Indexed: 12/16/2022]
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5
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Pietak A, Levin M. Bioelectrical control of positional information in development and regeneration: A review of conceptual and computational advances. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 137:52-68. [PMID: 29626560 PMCID: PMC10464501 DOI: 10.1016/j.pbiomolbio.2018.03.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 03/23/2018] [Accepted: 03/26/2018] [Indexed: 12/16/2022]
Abstract
Positional information describes pre-patterns of morphogenetic substances that alter spatio-temporal gene expression to instruct development of growth and form. A wealth of recent data indicate bioelectrical properties, such as the transmembrane potential (Vmem), are involved as instructive signals in the spatiotemporal regulation of morphogenesis. However, the mechanistic relationships between Vmem and molecular positional information are only beginning to be understood. Recent advances in computational modeling are assisting in the development of comprehensive frameworks for mechanistically understanding how endogenous bioelectricity can guide anatomy in a broad range of systems. Vmem represents an extraordinarily strong electric field (∼1.0 × 106 V/m) active over the thin expanse of the plasma membrane, with the capacity to influence a variety of downstream molecular signaling cascades. Moreover, in multicellular networks, intercellular coupling facilitated by gap junction channels may induce directed, electrodiffusive transport of charged molecules between cells of the network to generate new positional information patterning possibilities and characteristics. Given the demonstrated role of Vmem in morphogenesis, here we review current understanding of how Vmem can integrate with molecular regulatory networks to control single cell state, and the unique properties bioelectricity adds to transport phenomena in gap junction-coupled cell networks to facilitate self-assembly of morphogen gradients and other patterns. Understanding how Vmem integrates with biochemical regulatory networks at the level of a single cell, and mechanisms through which Vmem shapes molecular positional information in multicellular networks, are essential for a deep understanding of body plan control in development, regeneration and disease.
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Affiliation(s)
| | - Michael Levin
- Allen Discovery Center at Tufts, USA; Center for Regenerative and Developmental Biology, Tufts University, Medford, MA, USA
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6
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Ye L, Guan L, Fan P, Liu Y, Xiong W, Liu R, Wei X, Zhu Y, Liu Y, Bai H. Effect of a Small Physiological Electric Field on Angiogenic Activity in First-Trimester Extravillous Trophoblast Cells. Reprod Sci 2018; 26:745-756. [PMID: 30111245 DOI: 10.1177/1933719118792102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Electrical stimulation induces significant angiogenesis in vivo. We have shown that electrical stimulation of trophoblast cells has important functions in aspects of angiogenesis. In this study, we investigated the effects of a direct current electrical field on trophoblast angiogenic tube formation. A 6-hour exposure to electric fields ranging from 50 to 150 mV/mm dose dependently increased tube growth and network formation. Additionally, the effect was time dependent, with increased tube formation occurring between 4 and 8 hours, indicating stimulation of trophoblast cell angiogenesis. Electrical fields of small physiological magnitude stimulated vascular endothelial growth factor expression by trophoblast cells in the culture. Electric field treatment also resulted in activation of Akt, while the activity of extracellular-regulated kinase 1/2, p38, and c-Jun NH2-terminal kinase was not significantly changed. Pretreatment with the vascular endothelial growth factor receptor (VEGFR)-2 inhibitor, SU1498, resulted in potent inhibition of tube growth, and the Akt inhibitor, MK-2206 2HCl, significantly reduced electric field-stimulated tubulogenesis. These data suggest the importance of the VEGFR-2 signaling pathway during electric field-induced trophoblastic angiogenesis. This novel evidence indicates that endogenous electrical fields may promote angiogenesis of trophoblast cells by stimulating the VEGFR signaling pathway.
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Affiliation(s)
- Liyan Ye
- Laboratory of Genetic Disease and Perinatal Medicine and Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, 610041, People's Republic of China
| | - Linbo Guan
- Laboratory of Genetic Disease and Perinatal Medicine and Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, 610041, People's Republic of China
| | - Ping Fan
- Laboratory of Genetic Disease and Perinatal Medicine and Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, 610041, People's Republic of China
| | - Yinghui Liu
- Department of Biochemistry and Molecular Biology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan, People's Republic of China
| | - Wei Xiong
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China
| | - Rui Liu
- Division of Peptides Related with Human Disease, West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China
| | - Xing Wei
- Laboratory of Genetic Disease and Perinatal Medicine and Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, 610041, People's Republic of China
| | - Yue Zhu
- Laboratory of Genetic Disease and Perinatal Medicine and Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, 610041, People's Republic of China
| | - Yu Liu
- Department of Biochemistry and Molecular Biology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan, People's Republic of China
| | - Huai Bai
- Laboratory of Genetic Disease and Perinatal Medicine and Key Laboratory of Birth Defects and Related Diseases of Women and Children of the Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, 610041, People's Republic of China.
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Busse SM, McMillen PT, Levin M. Cross-limb communication during Xenopus hind-limb regenerative response: non-local bioelectric injury signals. Development 2018; 145:dev.164210. [DOI: 10.1242/dev.164210] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 07/31/2018] [Indexed: 12/29/2022]
Abstract
Regeneration of damaged body-parts requires coordination of size, shape, location, and orientation of tissue with the rest of the body. It is not currently known how far injury sites communicate with the remaining soma during repair, or what information may emanate from the injury site to other regions. We examined the bioelectric properties (resting potential gradients in the epidermis) of Xenopus froglets undergoing hind-limb amputation and observed that the contralateral (un-damaged) limb exhibits apparent depolarization signals immediately after the opposite hind-limb is amputated. The pattern of depolarization matches that of the amputated limb and is correlated to the position and type of injury, revealing that information about damage is available to remote body tissues and is detectable non-invasively in vivo by monitoring of the bioelectric state. These data extend knowledge about the electrophysiology of regenerative response, identify a novel communication process via long-range spread of injury signaling, a phenomenon which we call bioelectric injury mirroring (BIM), and suggests revisions to regenerative medicine and diagnostic strategies focused entirely on the wound site and to the use of contralateral limbs as controls.
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Affiliation(s)
- Sera M. Busse
- Biology Department and Allen Discovery Center, Tufts University, Medford, MA 02155, USA
| | - Patrick T. McMillen
- Biology Department and Allen Discovery Center, Tufts University, Medford, MA 02155, USA
| | - Michael Levin
- Biology Department and Allen Discovery Center, Tufts University, Medford, MA 02155, USA
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8
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McDowell G, Rajadurai S, Levin M. From cytoskeletal dynamics to organ asymmetry: a nonlinear, regulative pathway underlies left-right patterning. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0409. [PMID: 27821521 DOI: 10.1098/rstb.2015.0409] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2016] [Indexed: 12/25/2022] Open
Abstract
Consistent left-right (LR) asymmetry is a fundamental aspect of the bodyplan across phyla, and errors of laterality form an important class of human birth defects. Its molecular underpinning was first discovered as a sequential pathway of left- and right-sided gene expression that controlled positioning of the heart and visceral organs. Recent data have revised this picture in two important ways. First, the physical origin of chirality has been identified; cytoskeletal dynamics underlie the asymmetry of single-cell behaviour and patterning of the LR axis. Second, the pathway is not linear: early disruptions that alter the normal sidedness of upstream asymmetric genes do not necessarily induce defects in the laterality of the downstream genes or in organ situs Thus, the LR pathway is a unique example of two fascinating aspects of biology: the interplay of physics and genetics in establishing large-scale anatomy, and regulative (shape-homeostatic) pathways that correct molecular and anatomical errors over time. Here, we review aspects of asymmetry from its intracellular, cytoplasmic origins to the recently uncovered ability of the LR control circuitry to achieve correct gene expression and morphology despite reversals of key 'determinant' genes. We provide novel functional data, in Xenopus laevis, on conserved elements of the cytoskeleton that drive asymmetry, and comparatively analyse it together with previously published results in the field. Our new observations and meta-analysis demonstrate that despite aberrant expression of upstream regulatory genes, embryos can progressively normalize transcriptional cascades and anatomical outcomes. LR patterning can thus serve as a paradigm of how subcellular physics and gene expression cooperate to achieve developmental robustness of a body axis.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.
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Affiliation(s)
- Gary McDowell
- Biology Department, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155-4243, USA.,Allen Discovery Center, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155-4243, USA
| | - Suvithan Rajadurai
- Biology Department, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155-4243, USA.,Allen Discovery Center, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155-4243, USA
| | - Michael Levin
- Biology Department, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155-4243, USA .,Allen Discovery Center, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155-4243, USA
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9
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Fields C, Levin M. Multiscale memory and bioelectric error correction in the cytoplasm-cytoskeleton-membrane system. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2017; 10. [DOI: 10.1002/wsbm.1410] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 08/19/2017] [Accepted: 10/04/2017] [Indexed: 12/12/2022]
Affiliation(s)
- Chris Fields
- 21 Rue des Lavandiéres, 11160 Caunes Minervois; France
| | - Michael Levin
- Allen Discovery Center at Tufts University; Medford MA USA
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10
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Moore D, Walker SI, Levin M. Cancer as a disorder of patterning information: computational and biophysical perspectives on the cancer problem. CONVERGENT SCIENCE PHYSICAL ONCOLOGY 2017. [DOI: 10.1088/2057-1739/aa8548] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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11
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Augustin H, McGourty K, Allen MJ, Madem SK, Adcott J, Kerr F, Wong CT, Vincent A, Godenschwege T, Boucrot E, Partridge L. Reduced insulin signaling maintains electrical transmission in a neural circuit in aging flies. PLoS Biol 2017; 15:e2001655. [PMID: 28902870 PMCID: PMC5597081 DOI: 10.1371/journal.pbio.2001655] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 08/04/2017] [Indexed: 12/11/2022] Open
Abstract
Lowered insulin/insulin-like growth factor (IGF) signaling (IIS) can extend healthy lifespan in worms, flies, and mice, but it can also have adverse effects (the “insulin paradox”). Chronic, moderately lowered IIS rescues age-related decline in neurotransmission through the Drosophila giant fiber system (GFS), a simple escape response neuronal circuit, by increasing targeting of the gap junctional protein innexin shaking-B to gap junctions (GJs). Endosomal recycling of GJs was also stimulated in cultured human cells when IIS was reduced. Furthermore, increasing the activity of the recycling small guanosine triphosphatases (GTPases) Rab4 or Rab11 was sufficient to maintain GJs upon elevated IIS in cultured human cells and in flies, and to rescue age-related loss of GJs and of GFS function. Lowered IIS thus elevates endosomal recycling of GJs in neurons and other cell types, pointing to a cellular mechanism for therapeutic intervention into aging-related neuronal disorders. Insulin and insulin-like growth factors play an important role in the nervous system development and function. Reduced insulin signaling, however, can improve symptoms of neurodegenerative diseases in different model organisms and protect against age-associated decline in neuronal function extending lifespan. Here, we analyze the effects of genetically attenuated insulin signaling on the escape response pathway in the fruit fly Drosophila melanogaster. This simple neuronal circuit is dominated by electrical synapses composed of the gap junctional shaking-B protein, which allows for the transfer of electrical impulses between cells. Transmission through the circuit is known to slow down with age. We show that this functional decline is prevented by systemic or circuit-specific suppression of insulin signaling due to the preservation of the number of gap junctional proteins in aging animals. Our experiments in a human cell culture system reveal increased membrane targeting of gap junctional proteins via small proteins Rab4 and Rab11 under reduced insulin conditions. We also find that increasing the level of these recycling-mediating proteins in flies preserves the escape response circuit output in old flies and suggests ways of improving the function of neuronal circuits dominated by electrical synapses during aging.
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Affiliation(s)
- Hrvoje Augustin
- Max Planck Institute for Biology of Aging, Köln, Germany
- Institute of Healthy Aging, and Genetics, Evolution, and Environment, University College London, London, United Kingdom
| | - Kieran McGourty
- Department of Structural and Molecular Biology, London, United Kingdom
| | - Marcus J. Allen
- School of Biosciences, University of Kent, Canterbury, Kent, United Kingdom
| | - Sirisha Kudumala Madem
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida, United States of America
| | - Jennifer Adcott
- Max Planck Institute for Biology of Aging, Köln, Germany
- Institute of Healthy Aging, and Genetics, Evolution, and Environment, University College London, London, United Kingdom
| | - Fiona Kerr
- Max Planck Institute for Biology of Aging, Köln, Germany
- Institute of Healthy Aging, and Genetics, Evolution, and Environment, University College London, London, United Kingdom
| | - Chi Tung Wong
- Max Planck Institute for Biology of Aging, Köln, Germany
| | - Alec Vincent
- Max Planck Institute for Biology of Aging, Köln, Germany
| | - Tanja Godenschwege
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida, United States of America
| | - Emmanuel Boucrot
- Department of Structural and Molecular Biology, London, United Kingdom
| | - Linda Partridge
- Max Planck Institute for Biology of Aging, Köln, Germany
- Institute of Healthy Aging, and Genetics, Evolution, and Environment, University College London, London, United Kingdom
- * E-mail:
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12
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Mathews J, Levin M. Gap junctional signaling in pattern regulation: Physiological network connectivity instructs growth and form. Dev Neurobiol 2017; 77:643-673. [PMID: 27265625 PMCID: PMC10478170 DOI: 10.1002/dneu.22405] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 05/27/2016] [Accepted: 05/31/2016] [Indexed: 12/19/2022]
Abstract
Gap junctions (GJs) are aqueous channels that allow cells to communicate via physiological signals directly. The role of gap junctional connectivity in determining single-cell functions has long been recognized. However, GJs have another important role: the regulation of large-scale anatomical pattern. GJs are not only versatile computational elements that allow cells to control which small molecule signals they receive and emit, but also establish connectivity patterns within large groups of cells. By dynamically regulating the topology of bioelectric networks in vivo, GJs underlie the ability of many tissues to implement complex morphogenesis. Here, a review of recent data on patterning roles of GJs in growth of the zebrafish fin, the establishment of left-right patterning, the developmental dysregulation known as cancer, and the control of large-scale head-tail polarity, and head shape in planarian regeneration has been reported. A perspective in which GJs are not only molecular features functioning in single cells, but also enable global neural-like dynamics in non-neural somatic tissues has been proposed. This view suggests a rich program of future work which capitalizes on the rapid advances in the biophysics of GJs to exploit GJ-mediated global dynamics for applications in birth defects, regenerative medicine, and morphogenetic bioengineering. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 643-673, 2017.
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Affiliation(s)
- Juanita Mathews
- Department of Biology, Tufts Center for Regenerative and Developmental Biology, Tufts University, Medford, MA
| | - Michael Levin
- Department of Biology, Tufts Center for Regenerative and Developmental Biology, Tufts University, Medford, MA
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Durant F, Lobo D, Hammelman J, Levin M. Physiological controls of large-scale patterning in planarian regeneration: a molecular and computational perspective on growth and form. REGENERATION (OXFORD, ENGLAND) 2016; 3:78-102. [PMID: 27499881 PMCID: PMC4895326 DOI: 10.1002/reg2.54] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 02/18/2016] [Accepted: 02/22/2016] [Indexed: 12/12/2022]
Abstract
Planaria are complex metazoans that repair damage to their bodies and cease remodeling when a correct anatomy has been achieved. This model system offers a unique opportunity to understand how large-scale anatomical homeostasis emerges from the activities of individual cells. Much progress has been made on the molecular genetics of stem cell activity in planaria. However, recent data also indicate that the global pattern is regulated by physiological circuits composed of ionic and neurotransmitter signaling. Here, we overview the multi-scale problem of understanding pattern regulation in planaria, with specific focus on bioelectric signaling via ion channels and gap junctions (electrical synapses), and computational efforts to extract explanatory models from functional and molecular data on regeneration. We present a perspective that interprets results in this fascinating field using concepts from dynamical systems theory and computational neuroscience. Serving as a tractable nexus between genetic, physiological, and computational approaches to pattern regulation, planarian pattern homeostasis harbors many deep insights for regenerative medicine, evolutionary biology, and engineering.
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Affiliation(s)
- Fallon Durant
- Department of Biology, Allen Discovery Center at Tufts University, Tufts Center for Regenerative and Developmental BiologyTufts UniversityMA02155USA
| | - Daniel Lobo
- Department of Biological SciencesUniversity of MarylandBaltimore County, 1000 Hilltop CircleBaltimoreMD21250USA
| | - Jennifer Hammelman
- Department of Biology, Allen Discovery Center at Tufts University, Tufts Center for Regenerative and Developmental BiologyTufts UniversityMA02155USA
| | - Michael Levin
- Department of Biology, Allen Discovery Center at Tufts University, Tufts Center for Regenerative and Developmental BiologyTufts UniversityMA02155USA
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14
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Trulioff AS, Malashichev YB, Ermakov AS. Artificial inversion of the left–right visceral asymmetry in vertebrates: Conceptual approaches and experimental solutions. Russ J Dev Biol 2015. [DOI: 10.1134/s1062360415060090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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15
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Pezzulo G, Levin M. Re-membering the body: applications of computational neuroscience to the top-down control of regeneration of limbs and other complex organs. Integr Biol (Camb) 2015; 7:1487-517. [PMID: 26571046 DOI: 10.1039/c5ib00221d] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A major goal of regenerative medicine and bioengineering is the regeneration of complex organs, such as limbs, and the capability to create artificial constructs (so-called biobots) with defined morphologies and robust self-repair capabilities. Developmental biology presents remarkable examples of systems that self-assemble and regenerate complex structures toward their correct shape despite significant perturbations. A fundamental challenge is to translate progress in molecular genetics into control of large-scale organismal anatomy, and the field is still searching for an appropriate theoretical paradigm for facilitating control of pattern homeostasis. However, computational neuroscience provides many examples in which cell networks - brains - store memories (e.g., of geometric configurations, rules, and patterns) and coordinate their activity towards proximal and distant goals. In this Perspective, we propose that programming large-scale morphogenesis requires exploiting the information processing by which cellular structures work toward specific shapes. In non-neural cells, as in the brain, bioelectric signaling implements information processing, decision-making, and memory in regulating pattern and its remodeling. Thus, approaches used in computational neuroscience to understand goal-seeking neural systems offer a toolbox of techniques to model and control regenerative pattern formation. Here, we review recent data on developmental bioelectricity as a regulator of patterning, and propose that target morphology could be encoded within tissues as a kind of memory, using the same molecular mechanisms and algorithms so successfully exploited by the brain. We highlight the next steps of an unconventional research program, which may allow top-down control of growth and form for numerous applications in regenerative medicine and synthetic bioengineering.
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Affiliation(s)
- G Pezzulo
- Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy
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16
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Chernet BT, Fields C, Levin M. Long-range gap junctional signaling controls oncogene-mediated tumorigenesis in Xenopus laevis embryos. Front Physiol 2015; 5:519. [PMID: 25646081 PMCID: PMC4298169 DOI: 10.3389/fphys.2014.00519] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 12/18/2014] [Indexed: 11/21/2022] Open
Abstract
In addition to the immediate microenvironment, long-range signaling may be an important component of cancer. Molecular-genetic analyses have implicated gap junctions-key mediators of cell-cell communication-in carcinogenesis. We recently showed that the resting voltage potential of distant cell groups is a key determinant of metastatic transformation and tumor induction. Here, we show in the Xenopus laevis model that gap junctional communication (GJC) is a modulator of the long-range bioelectric signaling that regulates tumor formation. Genetic disruption of GJC taking place within tumors, within remote host tissues, or between the host and tumors significantly lowers the incidence of tumors induced by KRAS mutations. The most pronounced suppression of tumor incidence was observed upon GJC disruption taking place farther away from oncogene-expressing cells, revealing a role for GJC in distant cells in the control of tumor growth. In contrast, enhanced GJC communication through the overexpression of wild-type connexin Cx26 increased tumor incidence. Our data confirm a role for GJC in tumorigenesis, and reveal that this effect is non-local. Based on these results and on published data on movement of ions through GJs, we present a quantitative model linking the GJC coupling and bioelectrical state of cells to the ability of oncogenes to initiate tumorigenesis. When integrated with data on endogenous bioelectric signaling during left-right patterning, the model predicts differential tumor incidence outcomes depending on the spatial configurations of gap junction paths relative to tumor location and major anatomical body axes. Testing these predictions, we found that the strongest influence of GJ modulation on tumor suppression by hyperpolarization occurred along the embryonic left-right axis. Together, these data reveal new, long-range aspects of cancer control by the host's physiological parameters.
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Affiliation(s)
- Brook T. Chernet
- Department of Biology, Tufts Center for Regenerative and Developmental Biology, Tufts UniversityMedford, MA, USA
| | | | - Michael Levin
- Department of Biology, Tufts Center for Regenerative and Developmental Biology, Tufts UniversityMedford, MA, USA
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Blum M, Schweickert A, Vick P, Wright CVE, Danilchik MV. Symmetry breakage in the vertebrate embryo: when does it happen and how does it work? Dev Biol 2014; 393:109-23. [PMID: 24972089 PMCID: PMC4481729 DOI: 10.1016/j.ydbio.2014.06.014] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 06/08/2014] [Accepted: 06/17/2014] [Indexed: 10/25/2022]
Abstract
Asymmetric development of the vertebrate embryo has fascinated embryologists for over a century. Much has been learned since the asymmetric Nodal signaling cascade in the left lateral plate mesoderm was detected, and began to be unraveled over the past decade or two. When and how symmetry is initially broken, however, has remained a matter of debate. Two essentially mutually exclusive models prevail. Cilia-driven leftward flow of extracellular fluids occurs in mammalian, fish and amphibian embryos. A great deal of experimental evidence indicates that this flow is indeed required for symmetry breaking. An alternative model has argued, however, that flow simply acts as an amplification step for early asymmetric cues generated by ion flux during the first cleavage divisions. In this review we critically evaluate the experimental basis of both models. Although a number of open questions persist, the available evidence is best compatible with flow-based symmetry breakage as the archetypical mode of symmetry breakage.
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Affiliation(s)
- Martin Blum
- University of Hohenheim, Institute of Zoology (220), Garbenstrasse 30, D-70593 Stuttgart, Germany.
| | - Axel Schweickert
- University of Hohenheim, Institute of Zoology (220), Garbenstrasse 30, D-70593 Stuttgart, Germany
| | - Philipp Vick
- University of Hohenheim, Institute of Zoology (220), Garbenstrasse 30, D-70593 Stuttgart, Germany
| | - Christopher V E Wright
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232-0494, USA
| | - Michael V Danilchik
- Department of Integrative Biosciences, Oregon Health & Science University, Portland, OR 97239-3098, USA
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18
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Stephen LA, Johnson EJ, Davis GM, McTeir L, Pinkham J, Jaberi N, Davey MG. The chicken left right organizer has nonmotile cilia which are lost in a stage-dependent manner in the talpid(3) ciliopathy. Genesis 2014; 52:600-13. [PMID: 24700455 PMCID: PMC4314677 DOI: 10.1002/dvg.22775] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 03/23/2014] [Accepted: 03/29/2014] [Indexed: 01/31/2023]
Abstract
Motile cilia are an essential component of the mouse, zebrafish, and Xenopus laevis Left Right Organizers, generating nodal flow and allowing the reception and transduction of mechanosensory signals. Nonmotile primary cilia are also an important component of the Left Right Organizer's chemosensory mechanism. It has been proposed in the chicken that signaling in Hensen's node, the Left Right Organizer of the chicken, is independent of cilia, based on a lack of evidence of motile cilia or nodal flow. It is speculated that the talpid3 chicken mutant, which has normal left–right patterning despite lacking cilia at many stages of development, is proof of this hypothesis. Here, we examine the evidence for cilia in Hensen's node and find that although cilia are present; they are likely to be immotile and incapable of generating nodal flow. Furthermore, we find that early planar cell polarity patterning and ciliogenesis is normal in early talpid3 chicken embryos. We conclude that patterning and development of the early talpid3 chicken is normal, but not necessarily independent of cilia. Although it appears that Hensen's node does not require motile cilia or the generation of motile flow, there may remain a requirement for cilia in the transduction of SHH signaling.
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Affiliation(s)
- Louise A Stephen
- Division of Developmental Biology, The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
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19
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Abstract
Many aspects of heart development are determined by the left right axis and as a result several congenital diseases have their origins in aberrant left-right patterning. Establishment of this axis occurs early in embryogenesis before formation of the linear heart tube yet impacts upon much later morphogenetic events. In this review I discuss the differing mechanisms by which left-right polarity is achieved in the mouse and chick embryos and comment on the evolution of this system. I then discus three major classes of cardiovascular defect associated with aberrant left-right patterning seen in mouse mutants and human disease. I describe phenotypes associated with the determination of atrial identity and venous connections, looping morphogenesis of the heart tube and finally the asymmetric remodelling of the embryonic branchial arch arterial system to form the leftward looped arch of aorta and associated great arteries. Where appropriate, I consider left right patterning defects from an evolutionary perspective, demonstrating how developmental processes have been modified in species over time and illustrating how comparative embryology can aide in our understanding of congenital heart disease.
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Affiliation(s)
- Iain M Dykes
- Department of Cardiovascular Medicine and Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Headington, Oxford, OX3 7BN, UK
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20
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Collins MM, Ryan AK. Are there conserved roles for the extracellular matrix, cilia, and junctional complexes in left-right patterning? Genesis 2014; 52:488-502. [PMID: 24668924 DOI: 10.1002/dvg.22774] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2014] [Accepted: 03/19/2014] [Indexed: 01/11/2023]
Abstract
Many different types of molecules have essential roles in patterning the left-right axis and directing asymmetric morphogenesis. In particular, the relationship between signaling molecules and transcription factors has been explored extensively. Another group of proteins implicated in left-right patterning are components of the extracellular matrix, apical junctions, and cilia. These structural molecules have the potential to participate in the conversion of morphogenetic cues from the extracellular environment into morphogenetic patterning via their interactions with the actin cytoskeleton. Although it has been relatively easy to temporally position these proteins within the hierarchy of the left-right patterning pathway, it has been more difficult to define how they mechanistically fit into these pathways. Consequently, our understanding of how these factors impart patterning information to influence the establishment of the left-right axis remains limited. In this review, we will discuss those structural molecules that have been implicated in early phases of left-right axis development.
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Affiliation(s)
- Michelle M Collins
- Department of Human Genetics, McGill University, Montréal, Québec, Canada
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21
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Vandenberg LN, Lemire JM, Levin M. It's never too early to get it Right: A conserved role for the cytoskeleton in left-right asymmetry. Commun Integr Biol 2013; 6:e27155. [PMID: 24505508 PMCID: PMC3912007 DOI: 10.4161/cib.27155] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 11/08/2013] [Accepted: 11/11/2013] [Indexed: 01/08/2023] Open
Abstract
For centuries, scientists and physicians have been captivated by the consistent left-right (LR) asymmetry of the heart, viscera, and brain. A recent study implicated tubulin proteins in establishing laterality in several experimental models, including asymmetric chemosensory receptor expression in C. elegans neurons, polarization of HL-60 human neutrophil-like cells in culture, and asymmetric organ placement in Xenopus. The same mutations that randomized asymmetry in these diverse systems also affect chirality in Arabidopsis, revealing a remarkable conservation of symmetry-breaking mechanisms among kingdoms. In Xenopus, tubulin mutants only affected LR patterning very early, suggesting that this axis is established shortly after fertilization. This addendum summarizes and extends the knowledge of the cytoskeleton's role in the patterning of the LR axis. Results from many species suggest a conserved role for the cytoskeleton as the initiator of asymmetry, and indicate that symmetry is first broken during early embryogenesis by an intracellular process.
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Affiliation(s)
- Laura N Vandenberg
- Biology Department; Center for Regenerative and Developmental Biology; Tufts University; Medford, MA USA ; Current affiliation: Department of Public Health; Division of Environmental Health Sciences; University of Massachusetts, Amherst; Amherst, MA USA
| | - Joan M Lemire
- Biology Department; Center for Regenerative and Developmental Biology; Tufts University; Medford, MA USA
| | - Michael Levin
- Biology Department; Center for Regenerative and Developmental Biology; Tufts University; Medford, MA USA
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22
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Levin M. Reprogramming cells and tissue patterning via bioelectrical pathways: molecular mechanisms and biomedical opportunities. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2013; 5:657-76. [PMID: 23897652 PMCID: PMC3841289 DOI: 10.1002/wsbm.1236] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 05/16/2013] [Accepted: 06/21/2013] [Indexed: 12/17/2022]
Abstract
Transformative impact in regenerative medicine requires more than the reprogramming of individual cells: advances in repair strategies for birth defects or injuries, tumor normalization, and the construction of bioengineered organs and tissues all require the ability to control large-scale anatomical shape. Much recent work has focused on the transcriptional and biochemical regulation of cell behavior and morphogenesis. However, exciting new data reveal that bioelectrical properties of cells and their microenvironment exert a profound influence on cell differentiation, proliferation, and migration. Ion channels and pumps expressed in all cells, not just excitable nerve and muscle, establish resting potentials that vary across tissues and change with significant developmental events. Most importantly, the spatiotemporal gradients of these endogenous transmembrane voltage potentials (Vmem ) serve as instructive patterning cues for large-scale anatomy, providing organ identity, positional information, and prepattern template cues for morphogenesis. New genetic and pharmacological techniques for molecular modulation of bioelectric gradients in vivo have revealed the ability to initiate complex organogenesis, change tissue identity, and trigger regeneration of whole vertebrate appendages. A large segment of the spatial information processing that orchestrates individual cells' programs toward the anatomical needs of the host organism is electrical; this blurs the line between memory and decision-making in neural networks and morphogenesis in nonneural tissues. Advances in cracking this bioelectric code will enable the rational reprogramming of shape in whole tissues and organs, revolutionizing regenerative medicine, developmental biology, and synthetic bioengineering.
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Affiliation(s)
- Michael Levin
- Tufts University, Department of Biology and Tufts Center for Regenerative and Developmental Biology, 200 Boston Ave., Suite 4600, Medford, MA 02155
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23
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Schumacher JA, Hsieh YW, Chen S, Pirri JK, Alkema MJ, Li WH, Chang C, Chuang CF. Intercellular calcium signaling in a gap junction-coupled cell network establishes asymmetric neuronal fates in C. elegans. Development 2013; 139:4191-201. [PMID: 23093425 DOI: 10.1242/dev.083428] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The C. elegans left and right AWC olfactory neurons specify asymmetric subtypes, one default AWC(OFF) and one induced AWC(ON), through a stochastic, coordinated cell signaling event. Intercellular communication between AWCs and non-AWC neurons via a NSY-5 gap junction network coordinates AWC asymmetry. However, the nature of intercellular signaling across the network and how individual non-AWC cells in the network influence AWC asymmetry is not known. Here, we demonstrate that intercellular calcium signaling through the NSY-5 gap junction neural network coordinates a precise 1AWC(ON)/1AWC(OFF) decision. We show that NSY-5 gap junctions in C. elegans cells mediate small molecule passage. We expressed vertebrate calcium-buffer proteins in groups of cells in the network to reduce intracellular calcium levels, thereby disrupting intercellular communication. We find that calcium in non-AWC cells of the network promotes the AWC(ON) fate, in contrast to the autonomous role of calcium in AWCs to promote the AWC(OFF) fate. In addition, calcium in specific non-AWCs promotes AWC(ON) side biases through NSY-5 gap junctions. Our results suggest a novel model in which calcium has dual roles within the NSY-5 network: autonomously promoting AWC(OFF) and non-autonomously promoting AWC(ON).
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Affiliation(s)
- Jennifer A Schumacher
- Division of Developmental Biology, Children's Hospital Medical Center Research Foundation, 240 Albert Sabin Way, Cincinnati, OH 45229, USA
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24
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Eley L, Turnpenny L, Yates LM, Craighead AS, Morgan D, Whistler C, Goodship JA, Strachan T. A perspective on inversin. Cell Biol Int 2013; 28:119-24. [PMID: 14984757 DOI: 10.1016/j.cellbi.2003.11.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2003] [Accepted: 11/04/2003] [Indexed: 01/19/2023]
Abstract
Over the past 5 years, there has been increasing evidence for the role of primary (9+0) cilia in renal physiology and in establishing the left-right axis. The cilia in the renal tract are immotile and thought to have a sensory function. Cilia at the murine embryonic node have a vortical movement that sets up a leftward flow. Inversin, the protein defective in the inv mouse and in patients with type-2 nephronophthisis, localizes to both renal and node primary cilia. However, we present evidence that it is also expressed before the node forms and that its subcellular localization in renal tubular cells is not confined to the cilia. Its role in both the pathway determining left-right axis and renal function remains to be elucidated.
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Affiliation(s)
- Lorraine Eley
- Institute of Human Genetics, University of Newcastle, International Centre for Life, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK
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25
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Neurally Derived Tissues in Xenopus laevis Embryos Exhibit a Consistent Bioelectrical Left-Right Asymmetry. Stem Cells Int 2012; 2012:353491. [PMID: 23346115 PMCID: PMC3544345 DOI: 10.1155/2012/353491] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 11/07/2012] [Indexed: 11/18/2022] Open
Abstract
Consistent left-right asymmetry in organ morphogenesis is a fascinating aspect of bilaterian development. Although embryonic patterning of asymmetric viscera, heart, and brain is beginning to be understood, less is known about possible subtle asymmetries present in anatomically identical paired structures. We investigated two important developmental events: physiological controls of eye development and specification of neural crest derivatives, in Xenopus laevis embryos. We found that the striking hyperpolarization of transmembrane potential (Vmem) demarcating eye induction usually occurs in the right eye field first. This asymmetry is randomized by perturbing visceral left-right patterning, suggesting that eye asymmetry is linked to mechanisms establishing primary laterality. Bilateral misexpression of a depolarizing channel mRNA affects primarily the right eye, revealing an additional functional asymmetry in the control of eye patterning by Vmem. The ATP-sensitive K+ channel subunit transcript, SUR1, is asymmetrically expressed in the eye primordia, thus being a good candidate for the observed physiological asymmetries. Such subtle asymmetries are not only seen in the eye: consistent asymmetry was also observed in the migration of differentiated melanocytes on the left and right sides. These data suggest that even anatomically symmetrical structures may possess subtle but consistent laterality and interact with other developmental left-right patterning pathways.
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26
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Bessodes N, Haillot E, Duboc V, Röttinger E, Lahaye F, Lepage T. Reciprocal signaling between the ectoderm and a mesendodermal left-right organizer directs left-right determination in the sea urchin embryo. PLoS Genet 2012; 8:e1003121. [PMID: 23271979 PMCID: PMC3521660 DOI: 10.1371/journal.pgen.1003121] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 10/12/2012] [Indexed: 02/01/2023] Open
Abstract
During echinoderm development, expression of nodal on the right side plays a crucial role in positioning of the rudiment on the left side, but the mechanisms that restrict nodal expression to the right side are not known. Here we show that establishment of left-right asymmetry in the sea urchin embryo relies on reciprocal signaling between the ectoderm and a left-right organizer located in the endomesoderm. FGF/ERK and BMP2/4 signaling are required to initiate nodal expression in this organizer, while Delta/Notch signaling is required to suppress formation of this organizer on the left side of the archenteron. Furthermore, we report that the H(+)/K(+)-ATPase is critically required in the Notch signaling pathway upstream of the S3 cleavage of Notch. Our results identify several novel players and key early steps responsible for initiation, restriction, and propagation of left-right asymmetry during embryogenesis of a non-chordate deuterostome and uncover a functional link between the H(+)/K(+)-ATPase and the Notch signaling pathway.
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Affiliation(s)
- Nathalie Bessodes
- UMR 7009 CNRS, Université de Pierre et Marie Curie (Paris 6), Observatoire Océanologique de Villefranche-sur-Mer, Villefranche-sur-Mer, France
| | - Emmanuel Haillot
- UMR 7009 CNRS, Université de Pierre et Marie Curie (Paris 6), Observatoire Océanologique de Villefranche-sur-Mer, Villefranche-sur-Mer, France
| | - Véronique Duboc
- UMR 7009 CNRS, Université de Pierre et Marie Curie (Paris 6), Observatoire Océanologique de Villefranche-sur-Mer, Villefranche-sur-Mer, France
| | - Eric Röttinger
- UMR 7009 CNRS, Université de Pierre et Marie Curie (Paris 6), Observatoire Océanologique de Villefranche-sur-Mer, Villefranche-sur-Mer, France
| | - François Lahaye
- UMR 7009 CNRS, Université de Pierre et Marie Curie (Paris 6), Observatoire Océanologique de Villefranche-sur-Mer, Villefranche-sur-Mer, France
| | - Thierry Lepage
- UMR 7009 CNRS, Université de Pierre et Marie Curie (Paris 6), Observatoire Océanologique de Villefranche-sur-Mer, Villefranche-sur-Mer, France
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27
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Paraxial left-sided nodal expression and the start of left-right patterning in the early chick embryo. Differentiation 2012; 84:380-91. [PMID: 23142734 DOI: 10.1016/j.diff.2012.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 09/08/2012] [Accepted: 09/10/2012] [Indexed: 11/20/2022]
Abstract
A common element during early left-right patterning of the vertebrate body is left-sided nodal expression in the early-somite stage lateral plate mesoderm. Leftward cell movements near the node of the gastrulating chick embryo recently offered a plausible mechanism for breaking the presomite-stage molecular symmetry in those vertebrates which lack rotating cilia on the notochord or equivalent tissues. However, the temporal and functional relationships between generation of the known morphological node asymmetry, onset of leftward cell movements and establishment of stable molecular asymmetry in the chick remain unresolved. This study uses high-resolution light microscopy and in situ gene expression analysis to show that intranodal cell rearrangement during the phase of counter-clockwise node torsion at stage 4+ is immediately followed by symmetry loss and rearrangement of shh and fgf8 expression in node epiblast between stages 5- and 5+. Surprisingly, left-sided nodal expression starts at stage 5-, too, but lies in the paraxial mesoderm next to the forming notochordal plate, and can be rendered symmetrical by minimal mechanical disturbance of distant tissue integrity at stage 4. The "premature" paraxial nodal expression together with morphological and molecular asymmetries in, and near, midline compartments occurring at defined substages of early gastrulation help to identify a new narrow time window for early steps in left-right patterning in the chick and support the concept of a causal relationship between a-still enigmatic-chiral (motor) protein, cell movements and incipient left-right asymmetry in the amniote embryo.
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28
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Huang GY, Xie LJ, Linask KL, Zhang C, Zhao XQ, Yang Y, Zhou GM, Wu YJ, Marquez-Rosado L, McElhinney DB, Goldmuntz E, Liu C, Lampe PD, Chatterjee B, Lo CW. Evaluating the role of connexin43 in congenital heart disease: Screening for mutations in patients with outflow tract anomalies and the analysis of knock-in mouse models. J Cardiovasc Dis Res 2012; 2:206-12. [PMID: 22135478 PMCID: PMC3224440 DOI: 10.4103/0975-3583.89804] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Background: GJA1 gene encodes a gap junction protein known as connexin 43 (Cx43). Cx43 is abundantly expressed in the ventricular myocardium and in cardiac neural crest cells. Cx43 is proposed to play an important role in human congenital heart disease, as GJA1 knock-out mice die neonatally from outflow tract obstruction. In addition, patients with visceroatrial heterotaxia or hypoplastic left heart syndrome were reported to have point mutations in GJA1 at residues that affect protein kinase phosphorylation and gating of the gap junction channel. However, as these clinical findings were not replicated in subsequent studies, the question remains about the contribution of GJA1 mutations in human congenital heart disease (CHD). Materials and Methods: We analyzed the GJA1 coding sequence in 300 patients with CHD from two clinical centers, focusing on outflow tract anomalies. This included 152 with Tetralogy of Fallot from over 200 patients exhibiting outflow tract anomalies, as well as other structural heart defects including atrioventricular septal defects and other valvar anomalies. Our sequencing analysis revealed only two silent nucleotide substitutions in 8 patients. To further assess the possible role of Cx43 in CHD, we also generated two knock-in mouse models with point mutations at serine residues subject to protein kinase C or casein kinase phosphorylation, sites that are known to regulate gating and trafficking of Cx43, respectively. Results: Both heterozygous and homozygous knock-in mice were long term viable and did not exhibit overt CHD. Conclusion: The combined clinical and knock-in mouse mutant studies indicate GJA1 mutation is not likely a major contributor to CHD, especially those involving outflow tract anomalies.
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Affiliation(s)
- Guo-Ying Huang
- Children's Hospital of Fudan University, Shanghai, China
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29
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Saund RS, Kanai-Azuma M, Kanai Y, Kim I, Lucero MT, Saijoh Y. Gut endoderm is involved in the transfer of left-right asymmetry from the node to the lateral plate mesoderm in the mouse embryo. Development 2012; 139:2426-35. [PMID: 22627279 DOI: 10.1242/dev.079921] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In the mouse, the initial signals that establish left-right (LR) asymmetry are determined in the node by nodal flow. These signals are then transferred to the lateral plate mesoderm (LPM) through cellular and molecular mechanisms that are not well characterized. We hypothesized that endoderm might play a role in this process because it is tightly apposed to the node and covers the outer surface of the embryo, and, just after nodal flow is established, higher Ca(2+) flux has been reported on the left side near the node, most likely in the endoderm cells. Here we studied the role of endoderm cells in the transfer of the LR asymmetry signal by analyzing mouse Sox17 null mutant embryos, which possess endoderm-specific defects. Sox17(-/-) embryos showed no expression or significantly reduced expression of LR asymmetric genes in the left LPM. In Sox17 mutant endoderm, the localization of connexin proteins on the cell membrane was greatly reduced, resulting in defective gap junction formation, which appeared to be caused by incomplete development of organized epithelial structures. Our findings suggest an essential role of endoderm cells in the signal transfer step from the node to the LPM, possibly using gap junction communication to establish the LR axis of the mouse.
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Affiliation(s)
- Ranajeet S Saund
- Department of Neurobiology and Anatomy, University of Utah Medical School, Salt Lake City, UT 84132-3401, USA
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30
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Walentek P, Beyer T, Thumberger T, Schweickert A, Blum M. ATP4a Is Required for Wnt-Dependent Foxj1 Expression and Leftward Flow in Xenopus Left-Right Development. Cell Rep 2012; 1:516-27. [DOI: 10.1016/j.celrep.2012.03.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 03/06/2012] [Accepted: 03/21/2012] [Indexed: 12/12/2022] Open
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31
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Abstract
The ramified architectures of organs such as the mammary gland and lung are generated via branching morphogenesis, a developmental process through which individual cells bud and pinch off of pre-existing epithelial sheets. Although specified by signaling programs, organ development requires integration of all aspects of the microenvironment. We describe the essential role of endogenous cellular contractility in the formation of branching tubes. We also highlight the role of exogenous forces in normal and aberrant branching.
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Affiliation(s)
- Celeste M Nelson
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA.
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32
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Beyer T, Thumberger T, Schweickert A, Blum M. Connexin26-mediated transfer of laterality cues in Xenopus. Biol Open 2012; 1:473-81. [PMID: 23213439 PMCID: PMC3507211 DOI: 10.1242/bio.2012760] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A cilia-driven leftward flow of extracellular fluid breaks bilateral symmetry in the dorsal midline of the neurula stage vertebrate embryo. The left-specific Nodal signaling cascade in the lateral plate mesoderm (LPM) is key to asymmetric morphogenesis and placement of organs during subsequent development. The nature of the initial asymmetric cue(s) as well as the transfer of information from the midline to the left side has remained elusive. Gap junctional communication has been previously involved in Xenopus left-right (LR) development, however a function at cleavage stages was inferred from inhibitor experiments. Here we show by heptanol-mediated block of connexin function that flow stages during neurulation represent the critical time window. Flow in Xenopus occurs at the gastrocoel roof plate (GRP), a ciliated sheath of cells of mesodermal fate transiently positioned within the dorsal epithelial lining of the forming archenteron. We reasoned that endodermal cells immediately adjacent to the GRP are important for transfer of asymmetry. A systematic screen identified two connexin genes, Cx26 and Cx32, which were co-expressed in these lateral endodermal cells. Gain- and loss-of-function experiments pinpointed Cx26 as the critical connexin for LR development, while Cx32 had no effect on laterality. Importantly, GRP morphology, ciliation and flow were not affected in Cx26 morphants. Our results demonstrate a decisive role of Cx26 in the transfer of laterality cues from the GRP to the left LPM, providing a novel access to the identification of the initial asymmetric signal generated by flow.
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Affiliation(s)
- Tina Beyer
- University of Hohenheim, Institute of Zoology, Garbenstrasse 30, 70593 Stuttgart, Germany
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33
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Peiris TH, Oviedo NJ. Gap junction proteins: master regulators of the planarian stem cell response to tissue maintenance and injury. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:109-17. [PMID: 22450236 DOI: 10.1016/j.bbamem.2012.03.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 02/24/2012] [Accepted: 03/09/2012] [Indexed: 11/26/2022]
Abstract
Gap junction (GJ) proteins are crucial mediators of cell-cell communication during embryogenesis, tissue regeneration and disease. GJ proteins form plasma membrane channels that facilitate passage of small molecules across cells and modulate signaling pathways and cellular behavior in different tissues. These properties have been conserved throughout evolution, and in most invertebrates GJ proteins are known as innexins. Despite their critical relevance for physiology and disease, the mechanisms by which GJ proteins modulate cell behavior are poorly understood. This review summarizes findings from recent work that uses planarian flatworms as a paradigm to analyze GJ proteins in the complexity of the whole organism. The planarian model allows access to a large pool of adult somatic stem cells (known as neoblasts) that support physiological cell turnover and tissue regeneration. Innexin proteins are present in planarians and play a fundamental role in controlling neoblast behavior. We discuss the possibility that GJ proteins participate as cellular sensors that inform neoblasts about local and systemic physiological demands. We believe that functional analyses of GJ proteins will bring a complementary perspective to studies that focus on the temporal expression of genes. Finally, integrating functional studies along with molecular genetics and epigenetic approaches would expand our understanding of cellular regulation in vivo and greatly enhance the possibilities for rationally modulating stem cell behavior in their natural environment. This article is part of a Special Issue entitled: The communicating junctions, roles and dysfunctions.
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Affiliation(s)
- T Harshani Peiris
- Department of Molecular and Cell Biology, University of California, Merced, CA 95343, USA
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Katsu K, Tokumori D, Tatsumi N, Suzuki A, Yokouchi Y. BMP inhibition by DAN in Hensen's node is a critical step for the establishment of left-right asymmetry in the chick embryo. Dev Biol 2011; 363:15-26. [PMID: 22202776 DOI: 10.1016/j.ydbio.2011.12.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 12/05/2011] [Accepted: 12/06/2011] [Indexed: 11/28/2022]
Abstract
During left-right (L-R) axis formation, Nodal is expressed in the node and has a central role in the transfer of L-R information in the vertebrate embryo. Bone morphogenetic protein (BMP) signaling also has an important role for maintenance of gene expression around the node. Several members of the Cerberus/Dan family act on L-R patterning by regulating activity of the transforming growth factor-β (TGF-β) family. We demonstrate here that chicken Dan plays a critical role in L-R axis formation. Chicken Dan is expressed in the left side of the node shortly after left-handed Shh expression and before the appearance of asymmetrically expressed genes in the lateral plate mesoderm (LPM). In vitro experiments revealed that DAN inhibited BMP signaling but not NODAL signaling. SHH had a positive regulatory effect on Dan expression while BMP4 had a negative effect. Using overexpression and RNA interference-mediated knockdown strategies, we demonstrate that Dan is indispensable for Nodal expression in the LPM and for Lefty-1 expression in the notochord. In the perinodal region, expression of Dan and Nodal was independent of each other. Nodal up-regulation by DAN required NODAL signaling, suggesting that DAN might act synergistically with NODAL. Our data indicate that Dan plays an essential role in the establishment of the L-R axis by inhibiting BMP signaling around the node.
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Affiliation(s)
- Kenjiro Katsu
- Division of Pattern Formation, Department of Organogenesis, Institute of Molecular Embryology and Genetics, 2-2-1 Honjo, Kumamoto 860-0811, Japan
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Vandenberg LN, Pennarola BW, Levin M. Low frequency vibrations disrupt left-right patterning in the Xenopus embryo. PLoS One 2011; 6:e23306. [PMID: 21826245 PMCID: PMC3149648 DOI: 10.1371/journal.pone.0023306] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 07/15/2011] [Indexed: 11/19/2022] Open
Abstract
The development of consistent left-right (LR) asymmetry across phyla is a fascinating question in biology. While many pharmacological and molecular approaches have been used to explore molecular mechanisms, it has proven difficult to exert precise temporal control over functional perturbations. Here, we took advantage of acoustical vibration to disrupt LR patterning in Xenopus embryos during tightly-circumscribed periods of development. Exposure to several low frequencies induced specific randomization of three internal organs (heterotaxia). Investigating one frequency (7 Hz), we found two discrete periods of sensitivity to vibration; during the first period, vibration affected the same LR pathway as nocodazole, while during the second period, vibration affected the integrity of the epithelial barrier; both are required for normal LR patterning. Our results indicate that low frequency vibrations disrupt two steps in the early LR pathway: the orientation of the LR axis with the other two axes, and the amplification/restriction of downstream LR signals to asymmetric organs.
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Affiliation(s)
- Laura N. Vandenberg
- Center for Regenerative and Developmental Biology, Tufts University, Medford, Massachusetts, United States of America
- Biology Department, Tufts University, Medford, Massachusetts, United States of America
| | - Brian W. Pennarola
- Biology Department, Tufts University, Medford, Massachusetts, United States of America
| | - Michael Levin
- Center for Regenerative and Developmental Biology, Tufts University, Medford, Massachusetts, United States of America
- Biology Department, Tufts University, Medford, Massachusetts, United States of America
- * E-mail:
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Kato Y. The multiple roles of Notch signaling during left-right patterning. Cell Mol Life Sci 2011; 68:2555-67. [PMID: 21544546 PMCID: PMC11114802 DOI: 10.1007/s00018-011-0695-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Revised: 03/28/2011] [Accepted: 04/19/2011] [Indexed: 10/18/2022]
Abstract
The establishment of left-right (LR) asymmetry is regulated by intricate signaling mechanisms during embryogenesis and this asymmetry is critical for morphogenesis as well as the positioning of internal organs within the organism. Recent progress including elucidation of ion transporters, leftward nodal flow, and regulation of asymmetric gene expression contributes to our understanding of how the breaking of the symmetry is initiated and how this laterality information is subsequently transmitted to the organ primordium. A number of developmental signaling pathways have been implicated in this complex process. In this review, we will focus on the roles of the Notch signaling pathway during development of LR asymmetry. The Notch signaling pathway is a short-range communication system between neighboring cells. While Notch signaling plays essential roles in regulating the morphogenesis of the node and left-specific expression of Nodal in the lateral plate mesoderm, a hallmark gene in LR patterning, Notch signaling also suppresses the expression of Pitx2 that is a direct downstream target of Nodal during later stages of development. This negative activity of Notch signaling towards left-specific activity was recently shown to be inhibited by the B cell lymphoma 6 (BCL6)/BCL6 co-repressor (BcoR) transcriptional repressor complex in a target-specific manner. The complex regulation of Notch-dependent gene expression for LR asymmetry will be highlighted in this review.
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Affiliation(s)
- Yoichi Kato
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306, USA.
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Asymmetry in parkinsonism, spreading pathogens and the nose. Parkinsonism Relat Disord 2011; 18:1-9. [PMID: 21752693 DOI: 10.1016/j.parkreldis.2011.06.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 06/17/2011] [Accepted: 06/18/2011] [Indexed: 11/20/2022]
Abstract
Parkinson's disease, as well as many other parkinsonisms, including most toxic, neurodegenerative and familial types are typically asymmetric. No explanation for this phenomenon exists. A summary of the frequency of asymmetry in a spectrum of parkinsonian disorders is provided. Evidence against asymmetry being the result of normal asymmetries of the substantia nigrais reviewed. Asymmetry either results from a greater susceptibility on one side or a spreading pathology entering or starting on one side of the CNS. With the increasing evidence for spreading pathologies (toxins, viruses, α-synuclein), knowledge of neuroanatomical connections, and literature implicating spreading pathogens from the enteric and olfactory nerves, potential explanations can be theorized and explored, including the possibility of a pathogen preferentially entering or originating in the olfactory bulb on one side, with subsequent involvement of the other side.
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Vandenberg LN, Levin M. Far from solved: a perspective on what we know about early mechanisms of left-right asymmetry. Dev Dyn 2010; 239:3131-46. [PMID: 21031419 PMCID: PMC10468760 DOI: 10.1002/dvdy.22450] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023] Open
Abstract
Consistent laterality is a crucial aspect of embryonic development, physiology, and behavior. While strides have been made in understanding unilaterally expressed genes and the asymmetries of organogenesis, early mechanisms are still poorly understood. One popular model centers on the structure and function of motile cilia and subsequent chiral extracellular fluid flow during gastrulation. Alternative models focus on intracellular roles of the cytoskeleton in driving asymmetries of physiological signals or asymmetric chromatid segregation, at much earlier stages. All three models trace the origin of asymmetry back to the chirality of cytoskeletal organizing centers, but significant controversy exists about how this intracellular chirality is amplified onto cell fields. Analysis of specific predictions of each model and crucial recent data on new mutants suggest that ciliary function may not be a broadly conserved, initiating event in left-right patterning. Many questions about embryonic left-right asymmetry remain open, offering fascinating avenues for further research in cell, developmental, and evolutionary biology.
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Affiliation(s)
- Laura N. Vandenberg
- Biology Department, and Tufts Center for Regenerative and Developmental Biology, Tufts University, Medford, Massachusetts
| | - Michael Levin
- Biology Department, and Tufts Center for Regenerative and Developmental Biology, Tufts University, Medford, Massachusetts
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Seson, a novel zinc finger protein, controls cilia integrity for the LR patterning during zebrafish embryogenesis. Biochem Biophys Res Commun 2010; 401:169-74. [DOI: 10.1016/j.bbrc.2010.08.124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Accepted: 08/27/2010] [Indexed: 02/07/2023]
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Aw S, Koster J, Pearson W, Nichols C, Shi NQ, Carneiro K, Levin M. The ATP-sensitive K(+)-channel (K(ATP)) controls early left-right patterning in Xenopus and chick embryos. Dev Biol 2010; 346:39-53. [PMID: 20643119 PMCID: PMC2937067 DOI: 10.1016/j.ydbio.2010.07.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 06/21/2010] [Accepted: 07/08/2010] [Indexed: 11/17/2022]
Abstract
Consistent left-right asymmetry requires specific ion currents. We characterize a novel laterality determinant in Xenopus laevis: the ATP-sensitive K(+)-channel (K(ATP)). Expression of specific dominant-negative mutants of the Xenopus Kir6.1 pore subunit of the K(ATP) channel induced randomization of asymmetric organ positioning. Spatio-temporally controlled loss-of-function experiments revealed that the K(ATP) channel functions asymmetrically in LR patterning during very early cleavage stages, and also symmetrically during the early blastula stages, a period when heretofore largely unknown events transmit LR patterning cues. Blocking K(ATP) channel activity randomizes the expression of the left-sided transcription of Nodal. Immunofluorescence analysis revealed that XKir6.1 is localized to basal membranes on the blastocoel roof and cell-cell junctions. A tight junction integrity assay showed that K(ATP) channels are required for proper tight junction function in early Xenopus embryos. We also present evidence that this function may be conserved to the chick, as inhibition of K(ATP) in the primitive streak of chick embryos randomizes the expression of the left-sided gene Sonic hedgehog. We propose a model by which K(ATP) channels control LR patterning via regulation of tight junctions.
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Affiliation(s)
- Sherry Aw
- Center for Regenerative and Developmental Biology, and Biology Department, Tufts University, Medford, MA 02155, USA
- Program in Biological and Biomedical Sciences, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Joseph Koster
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Wade Pearson
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Colin Nichols
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Nian-Qing Shi
- Department of Medicine, University of Wisconsin, Madison, WI 53706, USA
| | - Katia Carneiro
- Center for Regenerative and Developmental Biology, and Biology Department, Tufts University, Medford, MA 02155, USA
| | - Michael Levin
- Center for Regenerative and Developmental Biology, and Biology Department, Tufts University, Medford, MA 02155, USA
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Francescatto L, Rothschild SC, Myers AL, Tombes RM. The activation of membrane targeted CaMK-II in the zebrafish Kupffer's vesicle is required for left-right asymmetry. Development 2010; 137:2753-62. [DOI: 10.1242/dev.049627] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Intracellular calcium ion (Ca2+) elevation on the left side of the mouse embryonic node or zebrafish Kupffer's vesicle (KV) is the earliest asymmetric molecular event that is functionally linked to lateral organ placement in these species. In this study, Ca2+/CaM-dependent protein kinase (CaMK-II) is identified as a necessary target of this Ca2+ elevation in zebrafish embryos. CaMK-II is transiently activated in approximately four interconnected cells along the anterior left wall of the KV between the six- and 12-somite stages, which is coincident with known left-sided Ca2+ elevations. Within these cells, activated CaMK-II is observed at the surface and in clusters, which appear at the base of some KV cilia. Although seven genes encode catalytically active CaMK-II in early zebrafish embryos, one of these genes also encodes a truncated inactive variant (αKAP) that can hetero-oligomerize with and target active enzyme to membranes. αKAP, β2 CaMK-II and γ1 CaMK-II antisense morpholino oligonucleotides, as well as KV-targeted dominant negative CaMK-II, randomize organ laterality and southpaw (spaw) expression in lateral plate mesoderm (LPM). Left-sided CaMK-II activation was most dependent on an intact KV, the PKD2 Ca2+ channel and γ1 CaMK-II; however, αKAP, β2 CaMK-II and the RyR3 ryanodine receptor were also necessary for full CaMK-II activation. This is the first report to identify a direct Ca2+-sensitive target in left-right asymmetry and supports a model in which membrane targeted CaMK-II hetero-oligomers in nodal cells transduce the left-sided PKD2-dependent Ca2+ signals to the LPM.
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Affiliation(s)
- Ludmila Francescatto
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284-2012, USA
| | - Sarah C. Rothschild
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284-2012, USA
| | - Alexandra L. Myers
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284-2012, USA
| | - Robert M. Tombes
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284-2012, USA
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42
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Vandenberg LN, Levin M. Consistent left-right asymmetry cannot be established by late organizers in Xenopus unless the late organizer is a conjoined twin. Development 2010; 137:1095-105. [PMID: 20215347 PMCID: PMC2835325 DOI: 10.1242/dev.041798] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2010] [Indexed: 12/28/2022]
Abstract
How embryos consistently orient asymmetries of the left-right (LR) axis is an intriguing question, as no macroscopic environmental cues reliably distinguish left from right. Especially unclear are the events coordinating LR patterning with the establishment of the dorsoventral (DV) axes and midline determination in early embryos. In frog embryos, consistent physiological and molecular asymmetries manifest by the second cell cleavage; however, models based on extracellular fluid flow at the node predict correct de novo asymmetry orientation during neurulation. We addressed these issues in Xenopus embryos by manipulating the timing and location of dorsal organizer induction: the primary dorsal organizer was ablated by UV irradiation, and a new organizer was induced at various locations, either early, by mechanical rotation, or late, by injection of lithium chloride (at 32 cells) or of the transcription factor XSiamois (which functions after mid-blastula transition). These embryos were then analyzed for the position of three asymmetric organs. Whereas organizers rescued before cleavage properly oriented the LR axis 90% of the time, organizers induced in any position at any time after the 32-cell stage exhibited randomized laterality. Late organizers were unable to correctly orient the LR axis even when placed back in their endogenous location. Strikingly, conjoined twins produced by late induction of ectopic organizers did have normal asymmetry. These data reveal that although correct LR orientation must occur no later than early cleavage stages in singleton embryos, a novel instructive influence from an early organizer can impose normal asymmetry upon late organizers in the same cell field.
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Affiliation(s)
- Laura N. Vandenberg
- Center for Regenerative and Developmental Biology, and Biology Department, Tufts University, Medford, MA 02155, USA
| | - Michael Levin
- Center for Regenerative and Developmental Biology, and Biology Department, Tufts University, Medford, MA 02155, USA
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44
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Taylor RW, Hsieh YW, Gamse JT, Chuang CF. Making a difference together: reciprocal interactions in C. elegans and zebrafish asymmetric neural development. Development 2010; 137:681-91. [PMID: 20147373 DOI: 10.1242/dev.038695] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Brain asymmetries are thought to increase neural processing capacity and to prevent interhemispheric conflict. In order to develop asymmetrically, neurons must be specified along the left-right axis, assigned left-side versus right-side identities and differentiate appropriately. In C. elegans and zebrafish, the cellular and molecular mechanisms that lead to neural asymmetries have recently come to light. Here, we consider recent insights into the mechanisms involved in asymmetrical neural development in these two species. Although the molecular details are divergent, both organisms use iterative cell-cell communication to establish left-right neuronal identity.
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Affiliation(s)
- Robert W Taylor
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
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45
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Oviedo NJ, Morokuma J, Walentek P, Kema IP, Gu MB, Ahn JM, Hwang JS, Gojobori T, Levin M. Long-range neural and gap junction protein-mediated cues control polarity during planarian regeneration. Dev Biol 2010; 339:188-99. [PMID: 20026026 PMCID: PMC2823934 DOI: 10.1016/j.ydbio.2009.12.012] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Revised: 11/11/2009] [Accepted: 12/09/2009] [Indexed: 01/24/2023]
Abstract
Having the ability to coordinate the behavior of stem cells to induce regeneration of specific large-scale structures would have far-reaching consequences in the treatment of degenerative diseases, acute injury, and aging. Thus, identifying and learning to manipulate the sequential steps that determine the fate of new tissue within the overall morphogenetic program of the organism is fundamental. We identified novel early signals, mediated by the central nervous system and 3 innexin proteins, which determine the fate and axial polarity of regenerated tissue in planarians. Modulation of gap junction-dependent and neural signals specifically induces ectopic anterior regeneration blastemas in posterior and lateral wounds. These ectopic anterior blastemas differentiate new brains that establish permanent primary axes re-established during subsequent rounds of unperturbed regeneration. These data reveal powerful novel controls of pattern formation and suggest a constructive model linking nervous inputs and polarity determination in early stages of regeneration.
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Affiliation(s)
- Néstor J. Oviedo
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University. Suite 4600, 200 Boston Avenue, Medford. MA 02155, USA
| | - Junji Morokuma
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University. Suite 4600, 200 Boston Avenue, Medford. MA 02155, USA
| | - Peter Walentek
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University. Suite 4600, 200 Boston Avenue, Medford. MA 02155, USA
| | - Ido P. Kema
- Department of Pathology and Laboratory Medicine University Medical Center Groningen, University of Groningen The Netherlands
| | - Man Bock Gu
- College of Life Science and Biotechnology, Korea University. Seoul, Republic of Korea
| | - Joo-Myung Ahn
- College of Life Science and Biotechnology, Korea University. Seoul, Republic of Korea
| | - Jung Shan Hwang
- Center for Information Biology and DNA Data Bank of Japan National Institute of Genetics. Yata 1111, Mishima Shizuoka 411-8540. Japan
| | - Takashi Gojobori
- Center for Information Biology and DNA Data Bank of Japan National Institute of Genetics. Yata 1111, Mishima Shizuoka 411-8540. Japan
| | - Michael Levin
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University. Suite 4600, 200 Boston Avenue, Medford. MA 02155, USA
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46
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Zhang Y, Levin M. Particle tracking model of electrophoretic morphogen movement reveals stochastic dynamics of embryonic gradient. Dev Dyn 2009; 238:1923-35. [PMID: 19618466 DOI: 10.1002/dvdy.22016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Some developmental events rely on an electrophoretic force to produce morphogenetic gradients. To quantitatively explore the dynamics of this process, we constructed a stochastic model of an early phase of left-right patterning: serotonin movement through the gap junction-coupled blastomeres of the Xenopus embryo. Particle-tracking simulations showed that a left-right gradient is formed rapidly, quickly reaching a final stable level. The voltage difference was critical for producing a morphogen gradient of the right steepness; gap junctional connectivity and morphogen mass determined the timing of the gradient. Endogenous electrophoresis drives approximately 50% of the particles across more than one cell width, and approximately 20% can travel across half the embryo. The stochastic behavior of the resulting gradients exhibited unexpected complexity among blastomeres' morphogen content, and showed how spatiotemporal variability within individual cells resulted in robust and consistent gradients across the embryonic left-right axis. Analysis of the distribution profile of gradient gain values made quantitative predictions about the conditions that result in the observed background level of laterality defects in unperturbed frog embryos. This work provides a general model that can be used to quantitatively analyze the unexpectedly complex dynamics of morphogens in a wide variety of systems.
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Affiliation(s)
- Ying Zhang
- Center for Regenerative and Developmental Biology, The Forsyth Institute, and Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts, USA
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47
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Hatler JM, Essner JJ, Johnson RG. A gap junction connexin is required in the vertebrate left-right organizer. Dev Biol 2009; 336:183-91. [PMID: 19799895 DOI: 10.1016/j.ydbio.2009.09.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 09/07/2009] [Accepted: 09/23/2009] [Indexed: 11/25/2022]
Abstract
Early patterning of vertebrate embryos involves the generation of asymmetric signals across the left-right (L-R) axis that position and are required for the proper function of internal organs. This patterning is directed by a conserved nodal/lefty signaling cascade on the left side of the embryo, thought to be asymmetrically directed by ciliary beating that generates a leftward fluid flow in the mammalian node and in Kupffer's vesicle (KV), the related structure in zebrafish. Following morpholino knockdown of Cx43.4, asymmetric gene expression and global organ distribution are randomized, consistent with the expression of Cx43.4 in KV. Randomization is recapitulated in mosaic embryos in which Cx43.4 is depleted preferentially in KV cells, showing that Cx43.4 is specifically required in KV for proper L-R axis formation. The mechanistic basis for the laterality anomalies in Cx43.4-deficient embryos is a primary morphogenesis defect during lumen formation in KV. Additionally, the role of Cx43.4 appears to be conserved given that its ortholog, human Cx45, is able to functionally compensate for zebrafish Cx43.4 during L-R patterning. This is the first report linking connexin function in the ciliated, node-like cells of KV with normal L-R axis development.
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Affiliation(s)
- Julia M Hatler
- Department of Genetics, Cell Biology and Development, University of Minnesota, 420 Washington Ave SE, MCB 6-150, Minneapolis, MN 55455, USA.
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48
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Blum M, Beyer T, Weber T, Vick P, Andre P, Bitzer E, Schweickert A. Xenopus, an ideal model system to study vertebrate left-right asymmetry. Dev Dyn 2009; 238:1215-25. [DOI: 10.1002/dvdy.21855] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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49
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Langenbacher A, Chen JN. Calcium signaling: a common thread in vertebrate left-right axis development. Dev Dyn 2009; 237:3491-6. [PMID: 18792114 DOI: 10.1002/dvdy.21704] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The establishment of a left-right axis during vertebrate development is essential for coordinating the relative positions of the internal organs to ensure that they function appropriately. Studies in numerous model organisms have revealed differences in regulative mechanisms upstream of nodal signaling, a conserved pathway in left-right axis specification. This review will summarize the diverse pathways involved in the break of left-right symmetry and explore in depth the multiple roles of calcium in vertebrate left-right axis specification.
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Affiliation(s)
- Adam Langenbacher
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
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50
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Abstract
Left-right patterning is a fascinating problem of morphogenesis, linking evolutionary and cellular signaling mechanisms across many levels of organization. In the past 15 years, enormous progress has been made in elucidating the molecular details of this process in embryos of several model species. While many outside the field seem to believe that the fundamental aspects of this pathway are now solved, workers on asymmetry are faced with considerable uncertainties over the details of specific mechanisms, a lack of conceptual unity of mechanisms across phyla, and important questions that are not being pursued in any of the popular model systems. Here, we suggest that data from clinical syndromes, cryptic asymmetries, and bilateral gynandromorphs, while not figuring prominently in the mainstream work on LR asymmetry, point to crucial and fundamental gaps of knowledge about asymmetry. We identify 12 big questions that provide exciting opportunities for fundamental new advances in this field.
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Affiliation(s)
- Sherry Aw
- Biological and Biomedical Sciences Program Harvard Medical School, and Center for Regenerative and Developmental Biology Forsyth Institute
| | - Michael Levin
- Center for Regenerative and Developmental Biology, Forsyth Institute, and Developmental Biology Department, Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, U.S.A., Tel. (617) 892-8403, Fax: (617) 892-8597,
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