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Pizzo L, Lasser M, Yusuff T, Jensen M, Ingraham P, Huber E, Singh MD, Monahan C, Iyer J, Desai I, Karthikeyan S, Gould DJ, Yennawar S, Weiner AT, Pounraja VK, Krishnan A, Rolls MM, Lowery LA, Girirajan S. Functional assessment of the "two-hit" model for neurodevelopmental defects in Drosophila and X. laevis. PLoS Genet 2021; 17:e1009112. [PMID: 33819264 PMCID: PMC8049494 DOI: 10.1371/journal.pgen.1009112] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 04/15/2021] [Accepted: 03/16/2021] [Indexed: 12/13/2022] Open
Abstract
We previously identified a deletion on chromosome 16p12.1 that is mostly inherited and associated with multiple neurodevelopmental outcomes, where severely affected probands carried an excess of rare pathogenic variants compared to mildly affected carrier parents. We hypothesized that the 16p12.1 deletion sensitizes the genome for disease, while "second-hits" in the genetic background modulate the phenotypic trajectory. To test this model, we examined how neurodevelopmental defects conferred by knockdown of individual 16p12.1 homologs are modulated by simultaneous knockdown of homologs of "second-hit" genes in Drosophila melanogaster and Xenopus laevis. We observed that knockdown of 16p12.1 homologs affect multiple phenotypic domains, leading to delayed developmental timing, seizure susceptibility, brain alterations, abnormal dendrite and axonal morphology, and cellular proliferation defects. Compared to genes within the 16p11.2 deletion, which has higher de novo occurrence, 16p12.1 homologs were less likely to interact with each other in Drosophila models or a human brain-specific interaction network, suggesting that interactions with "second-hit" genes may confer higher impact towards neurodevelopmental phenotypes. Assessment of 212 pairwise interactions in Drosophila between 16p12.1 homologs and 76 homologs of patient-specific "second-hit" genes (such as ARID1B and CACNA1A), genes within neurodevelopmental pathways (such as PTEN and UBE3A), and transcriptomic targets (such as DSCAM and TRRAP) identified genetic interactions in 63% of the tested pairs. In 11 out of 15 families, patient-specific "second-hits" enhanced or suppressed the phenotypic effects of one or many 16p12.1 homologs in 32/96 pairwise combinations tested. In fact, homologs of SETD5 synergistically interacted with homologs of MOSMO in both Drosophila and X. laevis, leading to modified cellular and brain phenotypes, as well as axon outgrowth defects that were not observed with knockdown of either individual homolog. Our results suggest that several 16p12.1 genes sensitize the genome towards neurodevelopmental defects, and complex interactions with "second-hit" genes determine the ultimate phenotypic manifestation.
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Affiliation(s)
- Lucilla Pizzo
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Micaela Lasser
- Department of Biology, Boston College, Chestnut Hill, MA, United States of America
| | - Tanzeen Yusuff
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Matthew Jensen
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Phoebe Ingraham
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Emily Huber
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Mayanglambam Dhruba Singh
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Connor Monahan
- Department of Biology, Boston College, Chestnut Hill, MA, United States of America
| | - Janani Iyer
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Inshya Desai
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Siddharth Karthikeyan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Dagny J. Gould
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Sneha Yennawar
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Alexis T. Weiner
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Vijay Kumar Pounraja
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Arjun Krishnan
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI, United States of America
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States of America
| | - Melissa M. Rolls
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Laura Anne Lowery
- Department of Medicine, Boston University Medical Center, Boston, MA, United States of America
| | - Santhosh Girirajan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
- Department of Anthropology, The Pennsylvania State University, University Park, PA, United States of America
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Desnitskiy AG. Surface contraction waves or cell proliferation waves in the presumptive neurectoderm during amphibian gastrulation: Mexican axolotl versus African clawed frog. Biosystems 2020; 198:104286. [PMID: 33181236 DOI: 10.1016/j.biosystems.2020.104286] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 09/21/2020] [Accepted: 11/03/2020] [Indexed: 11/19/2022]
Abstract
This essay represents a critical analysis of the literary data on various types of waves occurring in the amphibian embryos during gastrulation. A surface contraction wave travels through the presumptive neurectoderm during Mexican axolotl gastrulation. This wave coincides temporally and spatially with involution of the inducing chordomesoderm and with the prospective neural plate. By contrast, there is no similar surface contraction wave during African clawed frog gastrulation. However, the clawed frog displays the waves of DNA synthesis and mitosis in the presumptive neurectoderm during gastrulation, whereas no such waves were discovered in axolotl gastrulae. These sets of experimental data are in accordance with the contemporary concept of considerable ontogenetic diversity of the class Amphibia.
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Affiliation(s)
- Alexey G Desnitskiy
- Department of Embryology, Saint-Petersburg State University, Universitetskaya nab 7/9, 199034, St. Petersburg, Russia.
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3
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Zimmerlin L, Zambidis ET. Pleiotropic roles of tankyrase/PARP proteins in the establishment and maintenance of human naïve pluripotency. Exp Cell Res 2020; 390:111935. [PMID: 32151493 DOI: 10.1016/j.yexcr.2020.111935] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 02/25/2020] [Accepted: 02/29/2020] [Indexed: 12/19/2022]
Abstract
Tankyrase 1 (TNKS1; PARP-5a) and Tankyrase 2 (TNKS2; PARP-5b) are poly-ADP-ribosyl-polymerase (PARP)-domain-containing proteins that regulate the activities of a wide repertoire of target proteins via post-translational addition of poly-ADP-ribose polymers (PARylation). Although tankyrases were first identified as regulators of human telomere elongation, important and expansive roles of tankyrase activity have recently emerged in the development and maintenance of stem cell states. Herein, we summarize the current state of knowledge of the various tankyrase-mediated activities that may promote human naïve and 'extended' pluripotency'. We review the putative role of tankyrase and PARP inhibition in trophectoderm specification, telomere elongation, DNA repair and chromosomal segregation, metabolism, and PTEN-mediated apoptosis. Importantly, tankyrases possess PARP-independent activities that include regulation of MDC1-associated DNA repair by homologous recombination (HR) and autophagy/pexophagy, which is an essential mechanism of protein synthesis in the preimplantation embryo. Additionally, tankyrases auto-regulate themselves via auto-PARylation which augments their cellular protein levels and potentiates their non-PARP tankyrase functions. We propose that these non-PARP-related activities of tankyrase proteins may further independently affect both naïve and extended pluripotency via mechanisms that remain undetermined. We broadly outline a hypothetical framework for how inclusion of a tankyrase/PARP inhibitor in small molecule cocktails may stabilize and potentiate naïve and extended pluripotency via pleiotropic routes and mechanisms.
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Affiliation(s)
- Ludovic Zimmerlin
- Institute for Cell Engineering, And Division of Pediatric Oncology, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, 733 N. Broadway, Miller Research Building, Room 755, Baltimore, MD, 21205, United States.
| | - Elias T Zambidis
- Institute for Cell Engineering, And Division of Pediatric Oncology, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, 733 N. Broadway, Miller Research Building, Room 755, Baltimore, MD, 21205, United States.
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Gaitán-Espitia JD, Hofmann GE. Gene expression profiling during the embryo-to-larva transition in the giant red sea urchin Mesocentrotus franciscanus. Ecol Evol 2017; 7:2798-2811. [PMID: 28428870 PMCID: PMC5395446 DOI: 10.1002/ece3.2850] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 01/20/2017] [Accepted: 02/01/2017] [Indexed: 01/24/2023] Open
Abstract
In echinoderms, major morphological transitions during early development are attributed to different genetic interactions and changes in global expression patterns that shape the regulatory program for the specification of embryonic territories. In order more thoroughly to understand these biological and molecular processes, we examined the transcriptome structure and expression profiles during the embryo‐to‐larva transition of a keystone species, the giant red sea urchin Mesocentrotus franciscanus. Using a de novo assembly approach, we obtained 176,885 transcripts from which 60,439 (34%) had significant alignments to known proteins. From these transcripts, ~80% were functionally annotated allowing the identification of ~2,600 functional, structural, and regulatory genes involved in developmental process. Analysis of expression profiles between gastrula and pluteus stages of M. franciscanus revealed 791 differentially expressed genes with 251 GO overrepresented terms. For gastrula, up‐regulated GO terms were mainly linked to cell differentiation and signal transduction involved in cell cycle checkpoints. In the pluteus stage, major GO terms were associated with phosphoprotein phosphatase activity, muscle contraction, and olfactory behavior, among others. Our evolutionary comparative analysis revealed that several of these genes and functional pathways are highly conserved among echinoids, holothuroids, and ophiuroids.
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Affiliation(s)
| | - Gretchen E Hofmann
- Department of Ecology, Evolution and Marine Biology University of California Santa Barbara CA USA
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Pulido R. PTEN: a yin-yang master regulator protein in health and disease. Methods 2016; 77-78:3-10. [PMID: 25843297 DOI: 10.1016/j.ymeth.2015.02.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 02/19/2015] [Indexed: 01/16/2023] Open
Abstract
The PTEN gene is a tumor suppressor gene frequently mutated in human tumors, which encodes a ubiquitous protein whose major activity is to act as a lipid phosphatase that counteracts the action of the oncogenic PI3K. In addition, PTEN displays protein phosphatase- and catalytically-independent activities. The physiologic control of PTEN function, and its inactivation in cancer and other human diseases, including some neurodevelopmental disorders, is upon the action of multiple regulatory mechanisms. This provides a wide spectrum of potential therapeutic approaches to reconstitute PTEN activity. By contrast, inhibition of PTEN function may be beneficial in a different group of human diseases, such as type 2 diabetes or neuroregeneration-related pathologies. This makes PTEN a functionally dual yin-yang protein with high potential in the clinics. Here, a brief overview on PTEN and its relation with human disease is presented.
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Affiliation(s)
- Rafael Pulido
- BioCruces Health Research Institute, Barakaldo, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
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6
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Shnitsar I, Bashkurov M, Masson GR, Ogunjimi AA, Mosessian S, Cabeza EA, Hirsch CL, Trcka D, Gish G, Jiao J, Wu H, Winklbauer R, Williams RL, Pelletier L, Wrana JL, Barrios-Rodiles M. PTEN regulates cilia through Dishevelled. Nat Commun 2015; 6:8388. [PMID: 26399523 PMCID: PMC4598566 DOI: 10.1038/ncomms9388] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 08/17/2015] [Indexed: 01/26/2023] Open
Abstract
Cilia are hair-like cellular protrusions important in many aspects of eukaryotic biology. For instance, motile cilia enable fluid movement over epithelial surfaces, while primary (sensory) cilia play roles in cellular signalling. The molecular events underlying cilia dynamics, and particularly their disassembly, are not well understood. Phosphatase and tensin homologue (PTEN) is an extensively studied tumour suppressor, thought to primarily act by antagonizing PI3-kinase signalling. Here we demonstrate that PTEN plays an important role in multicilia formation and cilia disassembly by controlling the phosphorylation of Dishevelled (DVL), another ciliogenesis regulator. DVL is a central component of WNT signalling that plays a role during convergent extension movements, which we show here are also regulated by PTEN. Our studies identify a novel protein substrate for PTEN that couples PTEN to regulation of cilia dynamics and WNT signalling, thus advancing our understanding of potential underlying molecular etiologies of PTEN-related pathologies.
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Affiliation(s)
- Iryna Shnitsar
- Center for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5
| | - Mikhail Bashkurov
- Center for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5
| | - Glenn R Masson
- Protein and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Abiodun A Ogunjimi
- Center for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5
| | - Sherly Mosessian
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California 90095, USA
| | - Eduardo Aguiar Cabeza
- Center for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5
| | - Calley L Hirsch
- Center for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5
| | - Daniel Trcka
- Center for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5
| | - Gerald Gish
- Center for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5
| | - Jing Jiao
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California 90095, USA
| | - Hong Wu
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, California 90095, USA
| | - Rudolf Winklbauer
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5
| | - Roger L Williams
- Protein and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Laurence Pelletier
- Center for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Jeffrey L Wrana
- Center for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Miriam Barrios-Rodiles
- Center for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5
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Phosphatase and Tensin Homologue: Novel Regulation by Developmental Signaling. JOURNAL OF SIGNAL TRANSDUCTION 2015; 2015:282567. [PMID: 26339505 PMCID: PMC4539077 DOI: 10.1155/2015/282567] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 06/06/2015] [Accepted: 07/01/2015] [Indexed: 11/18/2022]
Abstract
Phosphatase and tensin homologue (PTEN) is a critical cell endogenous inhibitor of phosphoinositide signaling in mammalian cells. PTEN dephosphorylates phosphoinositide trisphosphate (PIP3), and by so doing PTEN has the function of negative regulation of Akt, thereby inhibiting this key intracellular signal transduction pathway. In numerous cell types, PTEN loss-of-function mutations result in unopposed Akt signaling, producing numerous effects on cells. Numerous reports exist regarding mutations in PTEN leading to unregulated Akt and human disease, most notably cancer. However, less is commonly known about nonmutational regulation of PTEN. This review focuses on an emerging literature on the regulation of PTEN at the transcriptional, posttranscriptional, translational, and posttranslational levels. Specifically, a focus is placed on the role developmental signaling pathways play in PTEN regulation; this includes insulin-like growth factor, NOTCH, transforming growth factor, bone morphogenetic protein, wnt, and hedgehog signaling. The regulation of PTEN by developmental mediators affects critical biological processes including neuronal and organ development, stem cell maintenance, cell cycle regulation, inflammation, response to hypoxia, repair and recovery, and cell death and survival. Perturbations of PTEN regulation consequently lead to human diseases such as cancer, chronic inflammatory syndromes, developmental abnormalities, diabetes, and neurodegeneration.
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8
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Pratt KG, Khakhalin AS. Modeling human neurodevelopmental disorders in the Xenopus tadpole: from mechanisms to therapeutic targets. Dis Model Mech 2013; 6:1057-65. [PMID: 23929939 PMCID: PMC3759326 DOI: 10.1242/dmm.012138] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The Xenopus tadpole model offers many advantages for studying the molecular, cellular and network mechanisms underlying neurodevelopmental disorders. Essentially every stage of normal neural circuit development, from axon outgrowth and guidance to activity-dependent homeostasis and refinement, has been studied in the frog tadpole, making it an ideal model to determine what happens when any of these stages are compromised. Recently, the tadpole model has been used to explore the mechanisms of epilepsy and autism, and there is mounting evidence to suggest that diseases of the nervous system involve deficits in the most fundamental aspects of nervous system function and development. In this Review, we provide an update on how tadpole models are being used to study three distinct types of neurodevelopmental disorders: diseases caused by exposure to environmental toxicants, epilepsy and seizure disorders, and autism.
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Affiliation(s)
- Kara G. Pratt
- University of Wyoming, 1000 E University Avenue, Laramie, WY 82071, USA
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9
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Taguchi A, Takii M, Motoishi M, Orii H, Mochii M, Watanabe K. Analysis of localization and reorganization of germ plasm in Xenopus transgenic line with fluorescence-labeled mitochondria. Dev Growth Differ 2013; 54:767-76. [PMID: 23067138 DOI: 10.1111/dgd.12005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Germ plasm is found in germ-line cells of Xenopus and thought to include the determinant of primordial germ cells (PGCs). As mitochondria is abundant in germ plasm, vital staining of mitochondria was used to analyze the movement and function of germ plasm; however, its application was limited in early cleavage embryos. We made transgenic Xenopus, harboring enhanced green fluorescent protein (EGFP) fused to the mitochondria transport signal (Dria-line). Germ plasm with EGFP-labeled mitochondria was clearly distinguishable from the other cytoplasm, and retained mostly during one generation of germ-line cells in Dria-line females. Using the Dria-line, we show that germ plasm is reorganized from near the cell membrane to the perinuclear space at St. 9, dependent on the microtubule system.
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Affiliation(s)
- Ayaka Taguchi
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akou-gun, Hyogo, 678-1297, Japan
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11
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Ueno S, Ueno T, Iwao Y. Role of the PI3K-TOR-S6K pathway in the onset of cell cycle elongation during Xenopus early embryogenesis. Dev Growth Differ 2011; 53:924-33. [PMID: 21958163 DOI: 10.1111/j.1440-169x.2011.01297.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In the early embryogenesis of the frog, Xenopus laevis, cells proliferate by rapid and synchronous divisions, followed by cell cycle elongation and prolongation of the S phases, and then the appearance of the G2 and G1 phases after the midblastula transition (MBT). The beginning of cell cycle elongation was thought to depend on an increase in the nucleo-cytoplasmic (N/C) ratio in blastomeres and a decrease in cortical cytoplasmic factors necessary for cell cycle progression, although these factors are unknown. In the present study, we demonstrated that a regulatory subunit of PI3K (p85α) was localized in the cortical cytoplasm of the blastomere during the MBT. When the embryos were treated with a PI3K inhibitor, LY294002, or a TOR inhibitor, rapamycin, cell cycle elongation was initiated before the MBT. In addition, the inhibition of S6K expression by antisense morpholino oligo enhanced the initiation of cell cycle elongation. In contrast, the activation of PI3K-TOR by Rheb-S16H expression delayed the initiation of cell cycle elongation. These results indicate that a decrease in translational activity dependent on the PI3K-TOR-S6K pathway causes the initiation of cell cycle elongation at the onset of the MBT.
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Affiliation(s)
- Shuichi Ueno
- Laboratory of Molecular Developmental Biology, Department of Applied Molecular Biosciences, Graduate School of Medicine, Yamaguchi University, 753-8512 Yamaguchi, Japan.
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12
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Ptenb mediates gastrulation cell movements via Cdc42/AKT1 in zebrafish. PLoS One 2011; 6:e18702. [PMID: 21494560 PMCID: PMC3073981 DOI: 10.1371/journal.pone.0018702] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 03/15/2011] [Indexed: 01/12/2023] Open
Abstract
Phosphatidylinositol 3-kinase (PI3 kinase) mediates gastrulation cell migration in zebrafish via its regulation of PIP2/PIP3 balance. Although PI3 kinase counter enzyme PTEN has also been reported to be essential for gastrulation, its role in zebrafish gastrulation has been controversial due to the lack of gastrulation defects in pten-null mutants. To clarify this issue, we knocked down a pten isoform, ptenb by using anti-sense morpholino oligos (MOs) in zebrafish embryos and found that ptenb MOs inhibit convergent extension by affecting cell motility and protrusion during gastrulation. The ptenb MO-induced convergence defect could be rescued by a PI3-kinase inhibitor, LY294002 and by overexpressing dominant negative Cdc42. Overexpression of human constitutively active akt1 showed similar convergent extension defects in zebrafish embryos. We also observed a clear enhancement of actin polymerization in ptenb morphants under cofocal microscopy and in actin polymerization assay. These results suggest that Ptenb by antagonizing PI3 kinase and its downstream Akt1 and Cdc42 to regulate actin polymerization that is critical for proper cell motility and migration control during gastrulation in zebrafish.
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Drinjakovic J, Jung H, Campbell DS, Strochlic L, Dwivedy A, Holt CE. E3 ligase Nedd4 promotes axon branching by downregulating PTEN. Neuron 2010; 65:341-57. [PMID: 20159448 PMCID: PMC2862300 DOI: 10.1016/j.neuron.2010.01.017] [Citation(s) in RCA: 159] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2010] [Indexed: 01/16/2023]
Abstract
Regulated protein degradation via the ubiquitin-proteasome system (UPS) plays a central role in building synaptic connections, yet little is known about either which specific UPS components are involved or UPS targets in neurons. We report that inhibiting the UPS in developing Xenopus retinal ganglion cells (RGCs) with a dominant-negative ubiquitin mutant decreases terminal branching in the tectum but does not affect long-range navigation to the tectum. We identify Nedd4 as a prominently expressed E3 ligase in RGC axon growth cones and show that disrupting its function severely inhibits terminal branching. We further demonstrate that PTEN, a negative regulator of the PI3K pathway, is a key downstream target of Nedd4: not only does Nedd4 regulate PTEN levels in RGC growth cones, but also, the decrease of PTEN rescues the branching defect caused by Nedd4 inhibition. Together our data suggest that Nedd4-regulated PTEN is a key regulator of terminal arborization in vivo.
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Affiliation(s)
- Jovana Drinjakovic
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Hosung Jung
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Douglas S. Campbell
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Laure Strochlic
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Asha Dwivedy
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Christine E. Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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Delta-Notch signaling is involved in the segregation of the three germ layers in Xenopus laevis. Dev Biol 2010; 339:477-92. [PMID: 20079726 DOI: 10.1016/j.ydbio.2010.01.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 01/06/2010] [Accepted: 01/07/2010] [Indexed: 11/20/2022]
Abstract
In vertebrates, the induction of the three germ layers (ectoderm, mesoderm and endoderm) has been extensively studied, but less is known about how they segregate. Here, we investigated whether Delta-Notch signaling is involved in this process. Activating the pathway in the marginal zone with Notch(ICD) resulted in an expansion of endodermal and neural ectoderm precursors, leaving a thinner mesodermal ring around the blastopore at gastrula stage, when germ layers are segregated. On the other hand, when the pathway was blocked with Delta-1(STU) or with an antisense morpholino oligonucleotide against Notch, the pan-mesodermal brachyury (bra) domain was expanded and the neural border was moved animalwards. Strikingly, the suprablastoporal endoderm was either expanded when Delta-1 signaling was blocked, or reduced after the general knock-down of Notch. In addition, either activating or blocking the pathway delays the blastopore closure. We conclude that the process of delimiting the three germ layers requires Notch signaling, which may be finely regulated by ligands and/or involve non-canonical components of the pathway. Moreover, Notch activity must be modulated at appropriate levels during this process in order to keep normal morphogenetic movements during gastrulation.
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Mammadova G, Iwasaki T, Tokmakov AA, Fukami Y, Sato KI. Evidence that phosphatidylinositol 3-kinase is involved in sperm-induced tyrosine kinase signaling in Xenopus egg fertilization. BMC DEVELOPMENTAL BIOLOGY 2009; 9:68. [PMID: 20015408 PMCID: PMC2805626 DOI: 10.1186/1471-213x-9-68] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Accepted: 12/17/2009] [Indexed: 11/10/2022]
Abstract
BACKGROUND Studies have examined the function of PI 3-kinase in the early developmental processes that operate in oocytes or early embryos of various species. However, the roles of egg-associated PI 3-kinase and Akt, especially in signal transduction at fertilization, are not well understood. RESULTS Here we show that in Xenopus eggs, a potent inhibitor of phosphatidylinositol 3-kinase (PI 3-kinase), LY294002 inhibits sperm-induced activation of the tyrosine kinase Src and a transient increase in the intracellular concentration of Ca2+ at fertilization. LY294002 also inhibits sperm-induced dephosphorylation of mitogen-activated protein kinase, breakdown of cyclin B2 and Mos, and first embryonic cleavage, all of which are events of Ca2+-dependent egg activation. In fertilized eggs, an 85-kDa subunit of PI 3-kinase (p85) undergoes a transient translocation to the low-density, detergent-insoluble membranes (membrane microdomains) where Src tyrosine kinase signaling is operating. However, the tyrosine phosphorylation of p85 in fertilized eggs is not as evident as that in H2O2-activated eggs, arguing against the possibility that PI 3-kinase is activated by Src phosphorylation. Nevertheless, sperm-induced activation of PI 3-kinase has been demonstrated by the finding that Akt, a serine/threonine-specific protein kinase, is phosphorylated at threonine-308. The threonine-phosphorylated Akt also localizes to the membrane microdomains of fertilized eggs. Application of bp(V), an inhibitor of PTEN that dephosphorylates PIP3, the enzymatic product of PI 3-kinase, promotes parthenogenetic activation of Xenopus eggs. In vitro kinase assays demonstrate that PIP3 activates Src in a dose-dependent manner. CONCLUSIONS These results suggest that PI 3-kinase is involved in sperm-induced egg activation via production of PIP3 that would act as a positive regulator of the Src signaling pathway in Xenopus fertilization.
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Affiliation(s)
- Gunay Mammadova
- The Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan.
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Altering PI3K-Akt signalling in zebrafish embryos affects PTEN phosphorylation and gastrulation. Biol Cell 2009; 101:661-78, 4 p following 678. [PMID: 19515017 DOI: 10.1042/bc20090034] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND INFORMATION PTEN (phosphatase and tensin homologue deleted on chromosome 10) is a negative regulator of the PI3K (phosphoinositide 3-kinase)-Akt (also called protein kinase B) signalling pathway and is essential for embryogenesis, but its function in early vertebrate embryos is unclear. RESULTS To address how PTEN functions in early embryos, we overexpressed one of the four zebrafish PTEN isoforms at the 1-2-cell stage. Overexpression of Ptena454 alters phospho-Akt levels and impairs cell movements associated with gastrulation. Heat shocking embryos increases phospho-Akt levels and lowers phospho-Ptena454 levels. Inhibiting CK2 (protein kinase CK2) activity reduces phospho-Pten levels and augments the effects due to Ptena454 overexpression. Low phospho-Akt and corresponding low phospho-GSK-3 (glycogen synthase kinase-3) and high phospho-Pten levels accompany wortmannin or LY294002 treatment, which inhibit PI3K activity. CONCLUSIONS These results suggest that Ptena454 regulation is correlated to changes in phospho-Akt levels. We propose a model in which homoeostasis in rapidly dividing and migrating embryonic cells depends on a counterbalance between pro-survival signalling employing CK2 and GSK-3 and the pro-apoptotic activity of Ptena454.
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17
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Assessment of PTEN tumor suppressor activity in nonmammalian models: the year of the yeast. Oncogene 2008; 27:5431-42. [DOI: 10.1038/onc.2008.240] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Nie S, Chang C. PI3K and Erk MAPK mediate ErbB signaling in Xenopus gastrulation. Mech Dev 2007; 124:657-67. [PMID: 17716876 PMCID: PMC2098746 DOI: 10.1016/j.mod.2007.07.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Revised: 06/18/2007] [Accepted: 07/12/2007] [Indexed: 12/22/2022]
Abstract
ErbB signaling regulates cell adhesion and movements during Xenopus gastrulation, but the downstream pathways involved have not been elucidated. In this study, we show that phosphatidylinositol-3 kinase (PI3K) and Erk mitogen-activated protein kinase (MAPK) mediate ErbB signaling to regulate gastrulation. Both PI3K and MAPK function sequentially in mesoderm specification and movements, and ErbB signaling is important only for the late phase activation of these pathways to control cell behaviors. Activation of either PI3K or Erk MAPK rescues gastrulation defects in ErbB4 morphant embryos, and restores convergent extension in the trunk mesoderm as well as coherent cell migration in the head mesoderm. The two signals preferentially regulate different aspects of cell behaviors, with PI3K more efficient in rescuing cell adhesion and spreading and MAPK more effective in stimulating the formation of filopodia. PI3K and MAPK also weakly activate each other, and together they modulate gastrulation movements. Our results reveal that PI3K and Erk MAPK, which have previously been considered as mesodermal inducing signals, also act downstream of ErbB signaling to participate in regulation of gastrulation morphogenesis.
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Affiliation(s)
| | - Chenbei Chang
- correspondent, ; 205-975-7229 (phone); 205-975-5648 (fax)
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