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Miao YH, Dou WH, Liu J, Huang DW, Xiao JH. Single-cell transcriptome sequencing reveals that Wolbachia induces gene expression changes in Drosophila ovary cells to favor its own maternal transmission. mBio 2024:e0147324. [PMID: 39194189 DOI: 10.1128/mbio.01473-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2024] [Accepted: 08/01/2024] [Indexed: 08/29/2024] Open
Abstract
Wolbachia is an obligate endosymbiont that is maternally inherited and widely distributed in arthropods and nematodes. It remains in the mature eggs of female hosts over generations through multiple strategies and manipulates the reproduction system of the host to enhance its spreading efficiency. However, the transmission of Wolbachia within the host's ovaries and its effects on ovarian cells during oogenesis, have not been extensively studied. We used single-cell RNA sequencing to comparatively analyze cell-typing and gene expression in Drosophila ovaries infected and uninfected with Wolbachia. Our findings indicate that Wolbachia significantly affects the transcription of host genes involved in the extracellular matrix, cytoskeleton organization, and cytomembrane mobility in multiple cell types, which may make host ovarian cells more conducive for the transmission of Wolbachia from extracellular to intracellular. Moreover, the genes nos and orb, which are related to the synthesis of ribonucleoprotein complexes, are specifically upregulated in early germline cells of ovaries infected with Wolbachia, revealing that Wolbachia can increase the possibility of its localization to the host oocytes by enhancing the binding with host ribonucleoprotein-complex processing bodies (P-bodies). All these findings provide novel insights into the maternal transmission of Wolbachia between host ovarian cells.IMPORTANCEWolbachia, an obligate endosymbiont in arthropods, can manipulate the reproduction system of the host to enhance its maternal transmission and reside in the host's eggs for generations. Herein, we performed single-cell RNA sequencing of ovaries from Drosophila melanogaster and observed the effects of Wolbachia (strain wMel) infection on different cell types to discuss the potential mechanism associated with the transmission and retention of Wolbachia within the ovaries of female hosts. It was found that the transcriptions of multiple genes in the ovary samples infected with Wolbachia are significantly altered, which possibly favors the maternal transmission of Wolbachia. Meanwhile, we also discovered that Wolbachia may flexibly regulate the expression level of specific host genes according to their needs rather than rigidly changing the expression level in one direction to achieve a more suitable living environment in the host's ovarian cells. Our findings contribute to a further understanding of the maternal transmission and possible universal effects of Wolbachia within the host.
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Affiliation(s)
- Yun-Heng Miao
- College of Life Sciences, Nankai University, Tianjin, China
| | - Wei-Hao Dou
- College of Life Sciences, Nankai University, Tianjin, China
| | - Jing Liu
- College of Life Sciences, Nankai University, Tianjin, China
| | - Da-Wei Huang
- College of Life Sciences, Nankai University, Tianjin, China
| | - Jin-Hua Xiao
- College of Life Sciences, Nankai University, Tianjin, China
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2
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Fang HY, Forghani R, Clarke A, McQueen PG, Chandrasekaran A, O’Neill KM, Losert W, Papoian GA, Giniger E. Enabled primarily controls filopodial morphology, not actin organization, in the TSM1 growth cone in Drosophila. Mol Biol Cell 2023; 34:ar83. [PMID: 37223966 PMCID: PMC10398877 DOI: 10.1091/mbc.e23-01-0003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 05/25/2023] Open
Abstract
Ena/VASP proteins are processive actin polymerases that are required throughout animal phylogeny for many morphogenetic processes, including axon growth and guidance. Here we use in vivo live imaging of morphology and actin distribution to determine the role of Ena in promoting the growth of the TSM1 axon of the Drosophila wing. Altering Ena activity causes stalling and misrouting of TSM1. Our data show that Ena has a substantial impact on filopodial morphology in this growth cone but exerts only modest effects on actin distribution. This is in contrast to the main regulator of Ena, Abl tyrosine kinase, which was shown previously to have profound effects on actin and only mild effects on TSM1 growth cone morphology. We interpret these data as suggesting that the primary role of Ena in this axon may be to link actin to the morphogenetic processes of the plasma membrane, rather than to regulate actin organization itself. These data also suggest that a key role of Ena, acting downstream of Abl, may be to maintain consistent organization and reliable evolution of growth cone structure, even as Abl activity varies in response to guidance cues in the environment.
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Affiliation(s)
- Hsiao Yu Fang
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Rameen Forghani
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Akanni Clarke
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Philip G. McQueen
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Aravind Chandrasekaran
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20752
| | - Kate M. O’Neill
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
- Institute for Physical Sciences and Department of Physics, University of Maryland, College Park, MD 20752
| | - Wolfgang Losert
- Institute for Physical Sciences and Department of Physics, University of Maryland, College Park, MD 20752
| | - Garegin A. Papoian
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20752
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
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3
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c-Abl Tyrosine Kinase Is Required for BDNF-Induced Dendritic Branching and Growth. Int J Mol Sci 2023; 24:ijms24031944. [PMID: 36768268 PMCID: PMC9916151 DOI: 10.3390/ijms24031944] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 01/09/2023] [Accepted: 01/09/2023] [Indexed: 01/20/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) induces activation of the TrkB receptor and several downstream pathways (MAPK, PI3K, PLC-γ), leading to neuronal survival, growth, and plasticity. It has been well established that TrkB signaling regulation is required for neurite formation and dendritic arborization, but the specific mechanism is not fully understood. The non-receptor tyrosine kinase c-Abl is a possible candidate regulator of this process, as it has been implicated in tyrosine kinase receptors' signaling and trafficking, as well as regulation of neuronal morphogenesis. To assess the role of c-Abl in BDNF-induced dendritic arborization, wild-type and c-Abl-KO neurons were stimulated with BDNF, and diverse strategies were employed to probe the function of c-Abl, including the use of pharmacological inhibitors, an allosteric c-Abl activator, and shRNA to downregulates c-Abl expression. Surprisingly, BDNF promoted c-Abl activation and interaction with TrkB receptors. Furthermore, pharmacological c-Abl inhibition and genetic ablation abolished BDNF-induced dendritic arborization and increased the availability of TrkB in the cell membrane. Interestingly, inhibition or genetic ablation of c-Abl had no effect on the classic TrkB downstream pathways. Together, our results suggest that BDNF/TrkB-dependent c-Abl activation is a novel and essential mechanism in TrkB signaling.
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Augustin V, Kins S. Fe65: A Scaffolding Protein of Actin Regulators. Cells 2021; 10:cells10071599. [PMID: 34202290 PMCID: PMC8304848 DOI: 10.3390/cells10071599] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 06/19/2021] [Accepted: 06/21/2021] [Indexed: 01/19/2023] Open
Abstract
The scaffolding protein family Fe65, composed of Fe65, Fe65L1, and Fe65L2, was identified as an interaction partner of the amyloid precursor protein (APP), which plays a key function in Alzheimer’s disease. All three Fe65 family members possess three highly conserved interaction domains, forming complexes with diverse binding partners that can be assigned to different cellular functions, such as transactivation of genes in the nucleus, modulation of calcium homeostasis and lipid metabolism, and regulation of the actin cytoskeleton. In this article, we rule out putative new intracellular signaling mechanisms of the APP-interacting protein Fe65 in the regulation of actin cytoskeleton dynamics in the context of various neuronal functions, such as cell migration, neurite outgrowth, and synaptic plasticity.
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Brabec JL, Lara MK, Tyler AL, Mahoney JM. System-Level Analysis of Alzheimer's Disease Prioritizes Candidate Genes for Neurodegeneration. Front Genet 2021; 12:625246. [PMID: 33889174 PMCID: PMC8056044 DOI: 10.3389/fgene.2021.625246] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/22/2021] [Indexed: 12/11/2022] Open
Abstract
Alzheimer’s disease (AD) is a debilitating neurodegenerative disorder. Since the advent of the genome-wide association study (GWAS) we have come to understand much about the genes involved in AD heritability and pathophysiology. Large case-control meta-GWAS studies have increased our ability to prioritize weaker effect alleles, while the recent development of network-based functional prediction has provided a mechanism by which we can use machine learning to reprioritize GWAS hits in the functional context of relevant brain tissues like the hippocampus and amygdala. In parallel with these developments, groups like the Alzheimer’s Disease Neuroimaging Initiative (ADNI) have compiled rich compendia of AD patient data including genotype and biomarker information, including derived volume measures for relevant structures like the hippocampus and the amygdala. In this study we wanted to identify genes involved in AD-related atrophy of these two structures, which are often critically impaired over the course of the disease. To do this we developed a combined score prioritization method which uses the cumulative distribution function of a gene’s functional and positional score, to prioritize top genes that not only segregate with disease status, but also with hippocampal and amygdalar atrophy. Our method identified a mix of genes that had previously been identified in AD GWAS including APOE, TOMM40, and NECTIN2(PVRL2) and several others that have not been identified in AD genetic studies, but play integral roles in AD-effected functional pathways including IQSEC1, PFN1, and PAK2. Our findings support the viability of our novel combined score as a method for prioritizing region- and even cell-specific AD risk genes.
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Affiliation(s)
- Jeffrey L Brabec
- Department of Neurological Sciences, University of Vermont, Burlington, VT, United States
| | - Montana Kay Lara
- Department of Neurological Sciences, University of Vermont, Burlington, VT, United States
| | - Anna L Tyler
- The Jackson Laboratory, Bar Harbor, ME, United States
| | - J Matthew Mahoney
- Department of Neurological Sciences, University of Vermont, Burlington, VT, United States.,The Jackson Laboratory, Bar Harbor, ME, United States
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6
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Kaur H, Sharma SK, Mandal S, Mandal L. Lar maintains the homeostasis of the hematopoietic organ in Drosophila by regulating insulin signaling in the niche. Development 2019; 146:dev.178202. [PMID: 31784462 DOI: 10.1242/dev.178202] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 11/18/2019] [Indexed: 12/12/2022]
Abstract
Stem cell compartments in metazoa get regulated by systemic factors as well as local stem cell niche-derived factors. However, the mechanisms by which systemic signals integrate with local factors in maintaining tissue homeostasis remain unclear. Employing the Drosophila lymph gland, which harbors differentiated blood cells, and stem-like progenitor cells and their niche, we demonstrate how a systemic signal interacts and harmonizes with local factor/s to achieve cell type-specific tissue homeostasis. Our genetic analyses uncovered a novel function of Lar, a receptor protein tyrosine phosphatase. Niche-specific loss of Lar leads to upregulated insulin signaling, causing increased niche cell proliferation and ectopic progenitor differentiation. Insulin signaling assayed by PI3K activation is downregulated after the second instar larval stage, a time point that coincides with the appearance of Lar in the hematopoietic niche. We further demonstrate that Lar physically associates with InR and serves as a negative regulator for insulin signaling in the Drosophila larval hematopoietic niche. Whether Lar serves as a localized invariable negative regulator of systemic signals such as insulin in other stem cell niches remains to be explored.
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Affiliation(s)
- Harleen Kaur
- Developmental Genetics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Manauli PO, Punjab 140306, India
| | - Shiv Kumar Sharma
- Developmental Genetics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Manauli PO, Punjab 140306, India
| | - Sudip Mandal
- Molecular Cell and Developmental Biology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Manauli PO, Punjab 140306, India
| | - Lolitika Mandal
- Developmental Genetics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Manauli PO, Punjab 140306, India
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PTPσ Drives Excitatory Presynaptic Assembly via Various Extracellular and Intracellular Mechanisms. J Neurosci 2018; 38:6700-6721. [PMID: 29934346 DOI: 10.1523/jneurosci.0672-18.2018] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/22/2018] [Accepted: 06/14/2018] [Indexed: 11/21/2022] Open
Abstract
Leukocyte common antigen-receptor protein tyrosine phosphatases (LAR-RPTPs) are hub proteins that organize excitatory and inhibitory synapse development through binding to various extracellular ligands. Here, we report that knockdown (KD) of the LAR-RPTP family member PTPσ reduced excitatory synapse number and transmission in cultured rat hippocampal neurons, whereas KD of PTPδ produced comparable decreases at inhibitory synapses, in both cases without altering expression levels of interacting proteins. An extensive series of rescue experiments revealed that extracellular interactions of PTPσ with Slitrks are important for excitatory synapse development. These experiments further showed that the intracellular D2 domain of PTPσ is required for induction of heterologous synapse formation by Slitrk1 or TrkC, suggesting that interaction of LAR-RPTPs with distinct intracellular presynaptic proteins, drives presynaptic machinery assembly. Consistent with this, double-KD of liprin-α2 and -α3 or KD of PTPσ substrates (N-cadherin and p250RhoGAP) in neurons inhibited Slitrk6-induced, PTPσ-mediated heterologous synapse formation activity. We propose a synaptogenesis model in presynaptic neurons involving LAR-RPTP-organized retrograde signaling cascades, in which both extracellular and intracellular mechanisms are critical in orchestrating distinct synapse types.SIGNIFICANCE STATEMENT In this study, we sought to test the unproven hypothesis that PTPσ and PTPδ are required for excitatory and inhibitory synapse formation/transmission, respectively, in cultured hippocampal neurons, using knockdown-based loss-of-function analyses. We further performed extensive structure-function analyses, focusing on PTPσ-mediated actions, to address the mechanisms of presynaptic assembly at excitatory synaptic sites. Using interdisciplinary approaches, we systematically applied a varied set of PTPσ deletion variants, point mutants, and splice variants to demonstrate that both extracellular and intracellular mechanisms are involved in organizing presynaptic assembly. Strikingly, extracellular interactions of PTPσ with heparan sulfates and Slitrks, intracellular interactions of PTPσ with liprin-α and its associated proteins through the D2 domain, as well as distinct substrates are all critical.
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8
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Su YH, Rastegri E, Kao SH, Lai CM, Lin KY, Liao HY, Wang MH, Hsu HJ. Diet regulates membrane extension and survival of niche escort cells for germline homeostasis via insulin signaling. Development 2018; 145:dev.159186. [DOI: 10.1242/dev.159186] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 03/09/2018] [Indexed: 12/29/2022]
Abstract
Diet is an important regulator of stem cell homeostasis, however, the underlying mechanisms of this regulation are not fully known. Here, we report that insulin signaling mediates dietary maintenance of Drosophila ovarian germline stem cells (GSCs) by promoting the extension of niche escort cell (EC) membranes to wrap around GSCs. This wrapping may facilitate the delivery of BMP stemness factors from ECs in the niche to GSCs. In addition to the effects on GSCs, insulin signaling-mediated regulation of EC number and protrusions controls the division and growth of GSC progeny. The effects of insulin signaling on EC membrane extension are, at least in part, driven by enhanced translation of Failed axon connections (Fax) via Ribosomal protein S6 kinase. Fax is a membrane protein that may participate in Abl-regulated cytoskeletal dynamics and is known to be involved in axon bundle formation. Therefore, we conclude that dietary cues stimulate insulin signaling in the niche to regulate EC cellular structure, probably via Fax-dependent cytoskeleton remodeling. This mechanism enhances intercellular contact and facilitates homeostatic interactions between somatic and germline cells in response to diet.
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Affiliation(s)
- Yu-Han Su
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Elham Rastegri
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Science, National Defense Medical Center, Taipei 11529, Taiwan
| | - Shih-Han Kao
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Chun-Min Lai
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica and National Chung-Hsing University, Taipei, 11529, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung 40227, Taiwan
- Biotechnology Center, National Chung-Hsing University, Taichung 40227, Taiwan
| | - Kun-Yang Lin
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica and National Chung-Hsing University, Taipei, 11529, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung 40227, Taiwan
- Biotechnology Center, National Chung-Hsing University, Taichung 40227, Taiwan
| | - Hung-Yu Liao
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Mu-Hsiang Wang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Hwei-Jan Hsu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Science, National Defense Medical Center, Taipei 11529, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung 40227, Taiwan
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9
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Cheong HSJ, VanBerkum MFA. Long disordered regions of the C-terminal domain of Abelson tyrosine kinase have specific and additive functions in regulation and axon localization. PLoS One 2017; 12:e0189338. [PMID: 29232713 PMCID: PMC5726718 DOI: 10.1371/journal.pone.0189338] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 11/22/2017] [Indexed: 01/28/2023] Open
Abstract
Abelson tyrosine kinase (Abl) is a key regulator of actin-related morphogenetic processes including axon guidance, where it functions downstream of several guidance receptors. While the long C-terminal domain (CTD) of Abl is required for function, its role is poorly understood. Here, a battery of mutants of Drosophila Abl was created that systematically deleted large segments of the CTD from Abl or added them back to the N-terminus alone. The functionality of these Abl transgenes was assessed through rescue of axon guidance defects and adult lethality in Abl loss-of-function, as well as through gain-of-function effects in sensitized slit or frazzled backgrounds that perturb midline guidance in the Drosophila embryonic nerve cord. Two regions of the CTD play important and distinct roles, but additive effects for other regions were also detected. The first quarter of the CTD, including a conserved PxxP motif and its surrounding sequence, regulates Abl function while the third quarter localizes Abl to axons. These regions feature long stretches of intrinsically disordered sequence typically found in hub proteins and are associated with diverse protein-protein interactions. Thus, the CTD of Abl appears to use these disordered regions to establish a variety of different signaling complexes required during formation of axon tracts.
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Affiliation(s)
- Han S J Cheong
- Department of Biological Sciences, Wayne State University, Detroit, United States of America
| | - Mark F A VanBerkum
- Department of Biological Sciences, Wayne State University, Detroit, United States of America
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10
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G-Protein Gα 13 Functions with Abl Kinase to Regulate Actin Cytoskeletal Reorganization. J Mol Biol 2017; 429:3836-3849. [PMID: 29079481 DOI: 10.1016/j.jmb.2017.10.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 10/17/2017] [Accepted: 10/18/2017] [Indexed: 11/23/2022]
Abstract
Heterotrimeric G-proteins are essential cellular signal transducers. One of the G-proteins, Gα13, is critical for actin cytoskeletal reorganization, cell migration, cell proliferation, and apoptosis. Previously, we have shown that Gα13 is essential for both G-protein-coupled receptor and receptor tyrosine kinase-induced actin cytoskeletal reorganization such as dynamic dorsal ruffle turnover and cell migration. However, the mechanism by which Gα13 signals to actin cytoskeletal reorganization is not completely understood. Here we show that Gα13 directly interacts with Abl tyrosine kinase, which is a critical regulator of actin cytoskeleton. This interaction is critical for Gα13-induced dorsal ruffle turnover, endothelial cell remodeling, and cell migration. Our data uncover a new molecular signaling pathway by which Gα13 controls actin cytoskeletal reorganization.
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11
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Tomatis VM, Josh P, Papadopulos A, Gormal RS, Lanoue V, Martin S, Meunier FA. ENA/VASP proteins regulate exocytosis by mediating myosin VI-dependent recruitment of secretory granules to the cortical actin network. Mol Cell Neurosci 2017; 84:100-111. [PMID: 28784263 DOI: 10.1016/j.mcn.2017.07.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/17/2017] [Accepted: 07/27/2017] [Indexed: 10/24/2022] Open
Abstract
In neurosecretory cells, myosin VI associated with secretory granules (SGs) mediates their activity-dependent recruitment to the cortical actin network and is necessary to sustain exocytosis. The mechanism by which myosin VI interacts with SGs is unknown. Using a myosin VI pull-down assay and mass spectrometry we identified Mena, a member of the ENA/VASP family, as a myosin VI binding partner in PC12 cells, and confirmed that Mena colocalized with myosin VI on SGs. Using a knock-sideways approach to inactivate the ENA/VASP family members by mitochondrial relocation, we revealed a concomitant redistribution of myosin VI. This was ensued by a reduction in the association of myosin VI with SGs, a decreased SG mobility and density in proximity to the plasma membrane as well as decreased evoked exocytosis. These data demonstrate that ENA/VASP proteins regulate SG exocytosis through modulating the activity of myosin VI.
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Affiliation(s)
- Vanesa M Tomatis
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Peter Josh
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Andreas Papadopulos
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Rachel S Gormal
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Vanessa Lanoue
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Sally Martin
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
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12
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Kannan R, Giniger E. New perspectives on the roles of Abl tyrosine kinase in axon patterning. Fly (Austin) 2017; 11:260-270. [PMID: 28481649 DOI: 10.1080/19336934.2017.1327106] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
The Abelson tyrosine kinase (Abl) lies at the heart of one of the small set of ubiquitous, conserved signal transduction pathways that do much of the work of development and physiology. Abl signaling is essential to epithelial integrity, motility of autonomous cells such as blood cells, and axon growth and guidance in the nervous system. However, though Abl was one of the first of these conserved signaling machines to be identified, it has been among the last to have its essential architecture elucidated. Here we will first discuss some of the challenges that long delayed the dissection of this pathway, and what they tell us about the special problems of investigating dynamic processes like motility. We will then describe our recent experiments that revealed the functional organization of the Abl pathway in Drosophila neurons. Finally, in the second part of the review we will introduce a different kind of complexity in the role of Abl in motility: the discovery of a previously unappreciated function in protein secretion and trafficking. We will provide evidence that the secretory function of Abl also contributes to its role in axon growth and guidance, and finally end with a discussion of the challenges that Abl pleiotropy provide for the investigator, but the opportunities that it provides for coordinating biological regulation.
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Affiliation(s)
- Ramakrishnan Kannan
- a Neurobiology Research Center (NRC), Department of Psychiatry , National Institute of Mental Health and Neurosciences , Bangalore , India
| | - Edward Giniger
- b National Institute of Neurological Disorders and Stroke, National Institutes of Health , Bethesda , MD
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13
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Kannan R, Song JK, Karpova T, Clarke A, Shivalkar M, Wang B, Kotlyanskaya L, Kuzina I, Gu Q, Giniger E. The Abl pathway bifurcates to balance Enabled and Rac signaling in axon patterning in Drosophila. Development 2017; 144:487-498. [PMID: 28087633 DOI: 10.1242/dev.143776] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 12/15/2016] [Indexed: 01/31/2023]
Abstract
The Abl tyrosine kinase signaling network controls cell migration, epithelial organization, axon patterning and other aspects of development. Although individual components are known, the relationships among them remain unresolved. We now use FRET measurements of pathway activity, analysis of protein localization and genetic epistasis to dissect the structure of this network in Drosophila We find that the adaptor protein Disabled stimulates Abl kinase activity. Abl suppresses the actin-regulatory factor Enabled, and we find that Abl also acts through the GEF Trio to stimulate the signaling activity of Rac GTPase: Abl gates the activity of the spectrin repeats of Trio, allowing them to relieve intramolecular repression of Trio GEF activity by the Trio N-terminal domain. Finally, we show that a key target of Abl signaling in axons is the WAVE complex that promotes the formation of branched actin networks. Thus, we show that Abl constitutes a bifurcating network, suppressing Ena activity in parallel with stimulation of WAVE. We suggest that the balancing of linear and branched actin networks by Abl is likely to be central to its regulation of axon patterning.
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Affiliation(s)
- Ramakrishnan Kannan
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jeong-Kuen Song
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tatiana Karpova
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Akanni Clarke
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Madhuri Shivalkar
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Benjamin Wang
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lyudmila Kotlyanskaya
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Irina Kuzina
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Qun Gu
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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Gautam NK, Verma P, Tapadia MG. Drosophila Malpighian Tubules: A Model for Understanding Kidney Development, Function, and Disease. Results Probl Cell Differ 2017; 60:3-25. [PMID: 28409340 DOI: 10.1007/978-3-319-51436-9_1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The Malpighian tubules of insects are structurally simple but functionally important organs, and their integrity is important for the normal excretory process. They are functional analogs of human kidneys which are important physiological organs as they maintain water and electrolyte balance in the blood and simultaneously help the body to get rid of waste and toxic products after various metabolic activities. In addition, it receives early indications of insults to the body such as immune challenge and other toxic components and is essential for sustaining life. According to National Vital Statistics Reports 2016, renal dysfunction has been ranked as the ninth most abundant cause of death in the USA. This chapter provides detailed descriptions of Drosophila Malpighian tubule development, physiology, immune function and also presents evidences that Malpighian tubules can be used as a model organ system to address the fundamental questions in developmental and functional disorders of the kidney.
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Affiliation(s)
- Naveen Kumar Gautam
- Embryotoxicology Laboratory, Environmental Toxicology Division, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow, 226001, Uttar Pradesh, India
| | - Puja Verma
- Department of Zoology, Cytogenetics Laboratory, Banaras Hindu University, Varanasi, 221005, Uttar Pradesh, India
| | - Madhu G Tapadia
- Department of Zoology, Cytogenetics Laboratory, Banaras Hindu University, Varanasi, 221005, Uttar Pradesh, India.
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15
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Vuong TA, Leem YE, Kim BG, Cho H, Lee SJ, Bae GU, Kang JS. A Sonic hedgehog coreceptor, BOC regulates neuronal differentiation and neurite outgrowth via interaction with ABL and JNK activation. Cell Signal 2016; 30:30-40. [PMID: 27871935 DOI: 10.1016/j.cellsig.2016.11.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 11/17/2016] [Indexed: 12/21/2022]
Abstract
Neurite outgrowth is a critical step for neurogenesis and remodeling synaptic circuitry during neuronal development and regeneration. An immunoglobulin superfamily member, BOC functions as Sonic hedgehog (Shh) coreceptor in canonical and noncanonical Shh signaling in neuronal development and axon outgrowth/guidance. However signaling mechanisms responsible for BOC action during these processes remain unknown. In our previous studies, a multiprotein complex containing BOC and a closely related protein CDO promotes myogenic differentiation through activation of multiple signaling pathways, including non-receptor tyrosine kinase ABL. Given that ABL and Jun. N-terminal kinase (JNK) are implicated in actin cytoskeletal dynamics required for neurogenesis, we investigated the relationship between BOC, ABL and JNK during neuronal differentiation. Here, we demonstrate that BOC and ABL are induced in P19 embryonal carcinoma (EC) cells and cortical neural progenitor cells (NPCs) during neuronal differentiation. BOC-depleted EC cells or Boc-/- NPCs exhibit impaired neuronal differentiation with shorter neurite formation. BOC interacts with ABL through its putative SH2 binding domain and seems to be phosphorylated in an ABL activity-dependent manner. Unlike wildtype BOC, ABL-binding defective BOC mutants exhibit impaired JNK activation and neuronal differentiation. Finally, Shh treatment enhances JNK activation which is diminished by BOC depletion. These data suggest that BOC interacts with ABL and activates JNK thereby promoting neuronal differentiation and neurite outgrowth.
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Affiliation(s)
- Tuan Anh Vuong
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Samsung Biomedical Research Institute, Suwon 16419, Republic of Korea
| | - Young-Eun Leem
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Samsung Biomedical Research Institute, Suwon 16419, Republic of Korea
| | - Bok-Geon Kim
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Samsung Biomedical Research Institute, Suwon 16419, Republic of Korea
| | - Hana Cho
- Department of Physiology, Sungkyunkwan University School of Medicine, Samsung Biomedical Research Institute, Suwon 16419, Republic of Korea
| | - Sang-Jin Lee
- Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul 04310, Republic of Korea
| | - Gyu-Un Bae
- Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul 04310, Republic of Korea
| | - Jong-Sun Kang
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Samsung Biomedical Research Institute, Suwon 16419, Republic of Korea.
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16
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Becker H, Renner S, Technau GM, Berger C. Cell-Autonomous and Non-cell-autonomous Function of Hox Genes Specify Segmental Neuroblast Identity in the Gnathal Region of the Embryonic CNS in Drosophila. PLoS Genet 2016; 12:e1005961. [PMID: 27015425 PMCID: PMC4807829 DOI: 10.1371/journal.pgen.1005961] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 03/04/2016] [Indexed: 12/12/2022] Open
Abstract
During central nervous system (CNS) development neural stem cells (Neuroblasts, NBs) have to acquire an identity appropriate to their location. In thoracic and abdominal segments of Drosophila, the expression pattern of Bithorax-Complex Hox genes is known to specify the segmental identity of NBs prior to their delamination from the neuroectoderm. Compared to the thoracic, ground state segmental units in the head region are derived to different degrees, and the precise mechanism of segmental specification of NBs in this region is still unclear. We identified and characterized a set of serially homologous NB-lineages in the gnathal segments and used one of them (NB6-4 lineage) as a model to investigate the mechanism conferring segment-specific identities to gnathal NBs. We show that NB6-4 is primarily determined by the cell-autonomous function of the Hox gene Deformed (Dfd). Interestingly, however, it also requires a non-cell-autonomous function of labial and Antennapedia that are expressed in adjacent anterior or posterior compartments. We identify the secreted molecule Amalgam (Ama) as a downstream target of the Antennapedia-Complex Hox genes labial, Dfd, Sex combs reduced and Antennapedia. In conjunction with its receptor Neurotactin (Nrt) and the effector kinase Abelson tyrosine kinase (Abl), Ama is necessary in parallel to the cell-autonomous Dfd pathway for the correct specification of the maxillary identity of NB6-4. Both pathways repress CyclinE (CycE) and loss of function of either of these pathways leads to a partial transformation (40%), whereas simultaneous mutation of both pathways leads to a complete transformation (100%) of NB6-4 segmental identity. Finally, we provide genetic evidences, that the Ama-Nrt-Abl-pathway regulates CycE expression by altering the function of the Hippo effector Yorkie in embryonic NBs. The disclosure of a non-cell-autonomous influence of Hox genes on neural stem cells provides new insight into the process of segmental patterning in the developing CNS. The central nervous system (CNS) needs to be subdivided into functionally specified regions. In the developing CNS of Drosophila, each neural stem cell, called neuroblasts (NB), acquires a unique identity according to its anterior-posterior and dorso-ventral position to generate a specific cell lineage. Along the anterior-posterior body axis, Hox genes of the Bithorax-Complex convey segmental identities to NBs in the trunk segments. In the derived gnathal and brain segments, the mechanisms specifying segmental NB identities are largely unknown. We investigated the role of Hox genes of the Antennapedia-Complex in the gnathal CNS. In addition to cell-autonomous Hox gene function, we unexpectedly uncovered a parallel non-cell-autonomous pathway in mediating segmental specification of embryonic NBs in gnathal segments. Both pathways restrict the expression of the cell cycle gene CyclinE, ensuring the proper specification of a glial cell lineage. Whereas the Hox gene Deformed mediates this cell-autonomously, labial and Antennapedia influence the identity via transcriptional regulation of the secreted molecule Amalgam (and its downstream pathway) in a non-cell-autonomous manner. These findings shed new light on the role of the highly conserved Hox genes during segmental patterning of neural stem cells in the CNS.
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Affiliation(s)
- Henrike Becker
- Institute of Genetics, University of Mainz, Mainz, Germany
| | - Simone Renner
- Institute of Genetics, University of Mainz, Mainz, Germany
| | - Gerhard M. Technau
- Institute of Genetics, University of Mainz, Mainz, Germany
- * E-mail: (CB); (GMT)
| | - Christian Berger
- Institute of Genetics, University of Mainz, Mainz, Germany
- * E-mail: (CB); (GMT)
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17
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Cammarata GM, Bearce EA, Lowery LA. Cytoskeletal social networking in the growth cone: How +TIPs mediate microtubule-actin cross-linking to drive axon outgrowth and guidance. Cytoskeleton (Hoboken) 2016; 73:461-76. [PMID: 26783725 DOI: 10.1002/cm.21272] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 01/08/2016] [Accepted: 01/08/2016] [Indexed: 11/08/2022]
Abstract
The growth cone is a unique structure capable of guiding axons to their proper destinations. Within the growth cone, extracellular guidance cues are interpreted and then transduced into physical changes in the actin filament (F-actin) and microtubule cytoskeletons, providing direction and movement. While both cytoskeletal networks individually possess important growth cone-specific functions, recent data over the past several years point towards a more cooperative role between the two systems. Facilitating this interaction between F-actin and microtubules, microtubule plus-end tracking proteins (+TIPs) have been shown to link the two cytoskeletons together. Evidence suggests that many +TIPs can couple microtubules to F-actin dynamics, supporting both microtubule advance and retraction in the growth cone periphery. In addition, growing in vitro and in vivo data support a secondary role for +TIPs in which they may participate as F-actin nucleators, thus directly influencing F-actin dynamics and organization. This review focuses on how +TIPs may link F-actin and microtubules together in the growth cone, and how these interactions may influence axon guidance. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
| | | | - Laura Anne Lowery
- Department of Biology, Boston College, Chestnut Hill, Massachusetts.
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18
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Czarnecki WM, Podlewska S, Bojarski AJ. Robust optimization of SVM hyperparameters in the classification of bioactive compounds. J Cheminform 2015; 7:38. [PMID: 26273325 PMCID: PMC4534515 DOI: 10.1186/s13321-015-0088-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 07/06/2015] [Indexed: 12/12/2022] Open
Abstract
Background Support Vector Machine has become one of the most popular machine learning tools used in virtual screening campaigns aimed at finding new drug candidates. Although it can be extremely effective in finding new potentially active compounds, its application requires the optimization of the hyperparameters with which the assessment is being run, particularly the C and \documentclass[12pt]{minimal}
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\begin{document}$$\gamma$$\end{document}γ values. The optimization requirement in turn, establishes the need to develop fast and effective approaches to the optimization procedure, providing the best predictive power of the constructed model. Results In this study, we investigated the Bayesian and random search optimization of Support Vector Machine hyperparameters for classifying bioactive compounds. The effectiveness of these strategies was compared with the most popular optimization procedures—grid search and heuristic choice. We demonstrated that Bayesian optimization not only provides better, more efficient classification but is also much faster—the number of iterations it required for reaching optimal predictive performance was the lowest out of the all tested optimization methods. Moreover, for the Bayesian approach, the choice of parameters in subsequent iterations is directed and justified; therefore, the results obtained by using it are constantly improved and the range of hyperparameters tested provides the best overall performance of Support Vector Machine. Additionally, we showed that a random search optimization of hyperparameters leads to significantly better performance than grid search and heuristic-based approaches. Conclusions The Bayesian approach to the optimization of Support Vector Machine parameters was demonstrated to outperform other optimization methods for tasks concerned with the bioactivity assessment of chemical compounds. This strategy not only provides a higher accuracy of classification, but is also much faster and more directed than other approaches for optimization. It appears that, despite its simplicity, random search optimization strategy should be used as a second choice if Bayesian approach application is not feasible.The improvement of classification accuracy obtained after the application of Bayesian approach to the optimization of Support Vector Machines parameters. ![]() Electronic supplementary material The online version of this article (doi:10.1186/s13321-015-0088-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Wojciech M Czarnecki
- Faculty of Mathematics and Computer Science, Jagiellonian University, 6 S. Lojasiewicza Street, 30-348 Krakow, Poland
| | - Sabina Podlewska
- Department of Medicinal Chemistry, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Krakow, Poland ; Faculty of Chemistry, Jagiellonian University, 3 Ingardena Street, 30-060 Krakow, Poland
| | - Andrzej J Bojarski
- Department of Medicinal Chemistry, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Krakow, Poland
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19
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Nesher E, Koman I, Gross M, Tikhonov T, Bairachnaya M, Salmon-Divon M, Levin Y, Gerlitz G, Michaelevski I, Yadid G, Pinhasov A. Synapsin IIb as a functional marker of submissive behavior. Sci Rep 2015; 5:10287. [PMID: 25998951 PMCID: PMC4441117 DOI: 10.1038/srep10287] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 04/09/2015] [Indexed: 12/22/2022] Open
Abstract
Dominance and submissiveness are important functional elements of the social hierarchy. By employing selective breeding based on a social interaction test, we developed mice with strong and stable, inheritable features of dominance and submissiveness. In order to identify candidate genes responsible for dominant and submissive behavior, we applied transcriptomic and proteomic studies supported by molecular, behavioral and pharmacological approaches. We clearly show here that the expression of Synapsin II isoform b (Syn IIb) is constitutively upregulated in the hippocampus and striatum of submissive mice in comparison to their dominant and wild type counterparts. Moreover, the reduction of submissive behavior achieved after mating and delivery was accompanied by a marked reduction of Syn IIb expression. Since submissiveness has been shown to be associated with depressive-like behavior, we applied acute SSRI (Paroxetine) treatment to reduce submissiveness in studied mice. We found that reduction of submissive behavior evoked by Paroxetine was paired with significantly decreased Syn IIb expression. In conclusion, our findings indicate that submissiveness, known to be an important element of depressive-like behavioral abnormalities, is strongly linked with changes in Syn IIb expression.
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Affiliation(s)
- Elimelech Nesher
- 1] Department of Molecular Biology. Ariel University, Ariel. Israel [2] Faculty of Life Sciences. Bar-Ilan University, Ramat Gan. Israel
| | - Igor Koman
- Department of Molecular Biology. Ariel University, Ariel. Israel
| | - Moshe Gross
- Department of Molecular Biology. Ariel University, Ariel. Israel
| | - Tatiana Tikhonov
- Department of Molecular Biology. Ariel University, Ariel. Israel
| | | | | | - Yishai Levin
- de Botton Institute for Protein Profiling, The Nancy and Stephen Grand Israel National Center for Personalized Medicine. Weizmann Institute of Science, Rehovot. Israel
| | - Gabi Gerlitz
- Department of Molecular Biology. Ariel University, Ariel. Israel
| | - Izhak Michaelevski
- 1] Department of Biochemistry and Molecular Biology. Tel-Aviv University, Tel-Aviv. Israel [2] Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv. Israel
| | - Gal Yadid
- Faculty of Life Sciences. Bar-Ilan University, Ramat Gan. Israel
| | - Albert Pinhasov
- Department of Molecular Biology. Ariel University, Ariel. Israel
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20
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Gonfloni S. Defying c-Abl signaling circuits through small allosteric compounds. Front Genet 2014; 5:392. [PMID: 25429298 PMCID: PMC4228975 DOI: 10.3389/fgene.2014.00392] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 10/25/2014] [Indexed: 11/13/2022] Open
Abstract
Many extracellular and intracellular signals promote the c-Abl tyrosine kinase activity. c-Abl in turn triggers a multitude of changes either in protein phosphorylation or in gene expression in the cell. Yet, c-Abl takes part in diverse signaling routes because of several domains linked to its catalytic core. Complex conformational changes turn on and off its kinase activity. These changes affect surface features of the c-Abl kinase and likely its capability to bind actin and/or DNA. Two specific inhibitors (ATP-competitive or allosteric compounds) regulate the c-Abl kinase through different mechanisms. NMR studies show that a c-Abl fragment (SH3-SH2-linker-SH1) adopts different conformational states upon binding to each inhibitor. This supports an unconventional use for allosteric compounds to unraveling physiological c-Abl signaling circuits.
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21
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Exploiting uncertainty measures in compounds activity prediction using support vector machines. Bioorg Med Chem Lett 2014; 25:100-5. [PMID: 25466199 DOI: 10.1016/j.bmcl.2014.11.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 10/31/2014] [Accepted: 11/01/2014] [Indexed: 11/23/2022]
Abstract
The great majority of molecular modeling tasks require the construction of a model that is then used to evaluate new compounds. Although various types of these models exist, at some stage, they all use knowledge about the activity of a given group of compounds, and the performance of the models is dependent on the quality of these data. Biological experiments verifying the activity of chemical compounds are often not reproducible; hence, databases containing these results often possess various activity records for a given molecule. In this study, we developed a method that incorporates the uncertainty of biological tests in machine-learning-based experiments using the Support Vector Machine as a classification model. We show that the developed methodology improves the classification effectiveness in the tested conditions.
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22
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Stine RR, Greenspan LJ, Ramachandran KV, Matunis EL. Coordinate regulation of stem cell competition by Slit-Robo and JAK-STAT signaling in the Drosophila testis. PLoS Genet 2014; 10:e1004713. [PMID: 25375180 PMCID: PMC4222695 DOI: 10.1371/journal.pgen.1004713] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 08/26/2014] [Indexed: 02/01/2023] Open
Abstract
Stem cells in tissues reside in and receive signals from local microenvironments called niches. Understanding how multiple signals within niches integrate to control stem cell function is challenging. The Drosophila testis stem cell niche consists of somatic hub cells that maintain both germline stem cells and somatic cyst stem cells (CySCs). Here, we show a role for the axon guidance pathway Slit-Roundabout (Robo) in the testis niche. The ligand Slit is expressed specifically in hub cells while its receptor, Roundabout 2 (Robo2), is required in CySCs in order for them to compete for occupancy in the niche. CySCs also require the Slit-Robo effector Abelson tyrosine kinase (Abl) to prevent over-adhesion of CySCs to the niche, and CySCs mutant for Abl outcompete wild type CySCs for niche occupancy. Both Robo2 and Abl phenotypes can be rescued through modulation of adherens junction components, suggesting that the two work together to balance CySC adhesion levels. Interestingly, expression of Robo2 requires JAK-STAT signaling, an important maintenance pathway for both germline and cyst stem cells in the testis. Our work indicates that Slit-Robo signaling affects stem cell function downstream of the JAK-STAT pathway by controlling the ability of stem cells to compete for occupancy in their niche.
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Affiliation(s)
- Rachel R. Stine
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Leah J. Greenspan
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Kapil V. Ramachandran
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Erika L. Matunis
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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23
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Analysis of Cdk5-related phosphoproteomics in growth cones. J Mol Neurosci 2014; 52:384-91. [PMID: 24234032 DOI: 10.1007/s12031-013-0162-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 10/23/2013] [Indexed: 10/26/2022]
Abstract
Neurons establish interactions with target cells via elongation and guidance of axons, and the growth cone plays pivotal roles in this process. Cyclin-dependent kinase 5 (Cdk5)is a key regulator of nervous system development. Cdk5 regulates several significant events by phosphorylating substrates that are involved in neurogenesis, and previous studies of Cdk5 have typically focused on single substrates. Here, we took anew approach to investigate Cdk5 substrates using mass spectrometry and bioinformatics analyses. Axonal growth cones were isolated and analyzed by HPLC-MALDI-MS/MS. In total, 178,617 MS/MS spectra were detected. Candidates were analyzed by GPS 2.1 and Scansite 3, which predicted that 2,664 and 275 sites, respectively, were potential phosphorylation sites of Cdk5. There were 190 overlapped phosphorylation sites, corresponding to 89 proteins. Those proteins correlated with axonal functions were classified, and two of them were verified using a classic site-specific mutation strategy. This is the first study in which the phosphoproteome of axonal growth cones was identified. The systematic examination of Cdk5 substrates could provide a reference for further study of molecular mechanisms of axonal growth cones, and new insights into treatments of neuronal disorders.
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24
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Tao W, Leng X, Chakraborty SN, Ma H, Arlinghaus RB. c-Abl activates janus kinase 2 in normal hematopoietic cells. J Biol Chem 2014; 289:21463-72. [PMID: 24923444 DOI: 10.1074/jbc.m114.554501] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Jak2 is involved in cytokine growth factor-stimulated signal transduction, but the mechanism of its activation is largely unknown. Here, we investigated Jak2 activation in a normal hematopoietic cell line, 32D mouse myeloid cells. The bimolecular fluorescence complementation studies showed that c-Abl formed a stable complex with Jak2 in live cells. Co-immunoprecipitation results showed that c-Abl bound to the βc chain of IL-3/IL-5/GM-CSF receptors. The kinase activities of both c-Abl and Jak2 were stimulated by IL-3 in 32D cells. Decreasing c-Abl protein expression in 32D cells by inducible shRNA decreased Jak2 activity and resulted in the failure of Jak2 activation in response to IL-3. Treatment of IL-3 and serum-starved 32D cells with 1 μM imatinib mysylate inhibited IL-3 stimulated kinase activities of both c-Abl and Jak2. In addition, the kinase-deficient Bcr-Abl mutant (p210K1172R) was defective for activation of Jak2 in 32D cells and impaired IL-3 independent growth, which was rescued by overexpression of c-Abl (+Abl). IL-3 efficiently inhibited apoptosis of 32Dp210K/R+Abl cells induced by imatinib mysylate but not Jak2 kinase inhibitor TG101209. In summary, our findings provide evidence that the kinase function of c-Abl and its C-terminal CT4 region is crucial for its interaction with Jak2 and its activation. c-Abl kinase activity induced by IL-3 is required for IL-3-stimulated Jak2 and Jak1 activation. Our findings reveal a novel regulatory role of c-Abl in Jak2 activation induced by IL-3 cytokine growth factor in 32D hematopoietic cells.
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Affiliation(s)
- Wenjing Tao
- From the Department of Translational Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Xiaohong Leng
- From the Department of Translational Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Sandip N Chakraborty
- From the Department of Translational Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Helen Ma
- From the Department of Translational Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Ralph B Arlinghaus
- From the Department of Translational Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
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25
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Loya CM, McNeill EM, Bao H, Zhang B, Van Vactor D. miR-8 controls synapse structure by repression of the actin regulator enabled. Development 2014; 141:1864-74. [PMID: 24718988 PMCID: PMC3994775 DOI: 10.1242/dev.105791] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression that play important roles in nervous system development and physiology. However, our understanding of the strategies by which miRNAs control synapse development is limited. We find that the highly conserved miRNA miR-8 regulates the morphology of presynaptic arbors at the Drosophila neuromuscular junction (NMJ) through a postsynaptic mechanism. Developmental analysis shows that miR-8 is required for presynaptic expansion that occurs in response to larval growth of the postsynaptic muscle targets. With an in vivo sensor, we confirm our hypothesis that the founding member of the conserved Ena/VASP (Enabled/Vasodilator Activated Protein) family is regulated by miR-8 through a conserved site in the Ena 3′ untranslated region (UTR). Synaptic marker analysis and localization studies suggest that Ena functions within the subsynaptic reticulum (SSR) surrounding presynaptic terminals. Transgenic lines that express forms of a conserved mammalian Ena ortholog further suggest that this localization and function of postsynaptic Ena/VASP family protein is dependent on conserved C-terminal domains known to mediate actin binding and assembly while antagonizing actin-capping proteins. Ultrastructural analysis demonstrates that miR-8 is required for SSR morphogenesis. As predicted by our model, we find that Ena is both sufficient and necessary to account for miR-8-mediated regulation of SSR architecture, consistent with its localization in this compartment. Finally, electrophysiological analysis shows that miR-8 is important for spontaneous neurotransmitter release frequency and quantal content. However, unlike the structural phenotypes, increased expression of Ena fails to mimic the functional defects observed in miR-8-null animals. Together, these findings suggest that miR-8 limits the expansion of presynaptic terminals during larval synapse development through regulation of postsynaptic actin assembly that is independent of changes in synapse physiology.
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Affiliation(s)
- Carlos M Loya
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
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26
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Abstract
The proper formation and morphogenesis of dendrites is fundamental to the establishment of neural circuits in the brain. Following cell cycle exit and migration, neurons undergo organized stages of dendrite morphogenesis, which include dendritic arbor growth and elaboration followed by retraction and pruning. Although these developmental stages were characterized over a century ago, molecular regulators of dendrite morphogenesis have only recently been defined. In particular, studies in Drosophila and mammalian neurons have identified numerous cell-intrinsic drivers of dendrite morphogenesis that include transcriptional regulators, cytoskeletal and motor proteins, secretory and endocytic pathways, cell cycle-regulated ubiquitin ligases, and components of other signaling cascades. Here, we review cell-intrinsic drivers of dendrite patterning and discuss how the characterization of such crucial regulators advances our understanding of normal brain development and pathogenesis of diverse cognitive disorders.
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Affiliation(s)
- Sidharth V Puram
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
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27
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Liu L, Wu CF. Distinct effects of Abelson kinase mutations on myocytes and neurons in dissociated Drosophila embryonic cultures: mimicking of high temperature. PLoS One 2014; 9:e86438. [PMID: 24466097 PMCID: PMC3897706 DOI: 10.1371/journal.pone.0086438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 12/07/2013] [Indexed: 11/18/2022] Open
Abstract
Abelson tyrosine kinase (Abl) is known to regulate axon guidance, muscle development, and cell-cell interaction in vivo. The Drosophila primary culture system offers advantages in exploring the cellular mechanisms mediated by Abl with utilizing various experimental manipulations. Here we demonstrate that single-embryo cultures exhibit stage-dependent characteristics of cellular differentiation and developmental progression in neurons and myocytes, as well as nerve-muscle contacts. In particular, muscle development critically depends on the stage of dissociated embryos. In wild-type (WT) cultures derived from embryos before stage 12, muscle cells remained within cell clusters and were rarely detected. Interestingly, abundant myocytes were spotted in Abl mutant cultures, exhibiting enhanced myocyte movement and fusion, as well as neuron-muscle contacts even in cultures dissociated from younger, stage 10 embryos. Notably, Abl myocytes frequently displayed well-expanded lamellipodia. Conversely, Abl neurons were characterized with fewer large veil-like lamellipodia, but instead had increased numbers of filopodia and darker nodes along neurites. These distinct phenotypes were equally evident in both homo- and hetero-zygous cultures (Abl/Abl vs. Abl/+) of different alleles (Abl1 and Abl4) indicating dominant mutational effects. Strikingly, in WT cultures derived from stage 10 embryos, high temperature (HT) incubation promoted muscle migration and fusion, partially mimicking the advanced muscle development typical of Abl cultures. However, HT enhanced neuronal growth with increased numbers of enlarged lamellipodia, distinct from the characteristic Abl neuronal morphology. Intriguingly, HT incubation also promoted Abl lamellipodia expansion, with a much greater effect on nerve cells than muscle. Our results suggest that Abl is an essential regulator for myocyte and neuron development and that high-temperature incubation partially mimics the faster muscle development typical of Abl cultures. Despite the extensive alterations by Abl mutations, we observed myocyte fusion events and nerve-muscle contact formation between WT and Abl cells in mixed WT and Abl cultures derived from labeled embryos.
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Affiliation(s)
- Lijuan Liu
- Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
| | - Chun-Fang Wu
- Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
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Mahul-Mellier AL, Fauvet B, Gysbers A, Dikiy I, Oueslati A, Georgeon S, Lamontanara AJ, Bisquertt A, Eliezer D, Masliah E, Halliday G, Hantschel O, Lashuel HA. c-Abl phosphorylates α-synuclein and regulates its degradation: implication for α-synuclein clearance and contribution to the pathogenesis of Parkinson's disease. Hum Mol Genet 2014; 23:2858-79. [PMID: 24412932 DOI: 10.1093/hmg/ddt674] [Citation(s) in RCA: 171] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Increasing evidence suggests that the c-Abl protein tyrosine kinase could play a role in the pathogenesis of Parkinson's disease (PD) and other neurodegenerative disorders. c-Abl has been shown to regulate the degradation of two proteins implicated in the pathogenesis of PD, parkin and α-synuclein (α-syn). The inhibition of parkin's neuroprotective functions is regulated by c-Abl-mediated phosphorylation of parkin. However, the molecular mechanisms by which c-Abl activity regulates α-syn toxicity and clearance remain unknown. Herein, using NMR spectroscopy, mass spectrometry, in vitro enzymatic assays and cell-based studies, we established that α-syn is a bona fide substrate for c-Abl. In vitro studies demonstrate that c-Abl directly interacts with α-syn and catalyzes its phosphorylation mainly at tyrosine 39 (pY39) and to a lesser extent at tyrosine 125 (pY125). Analysis of human brain tissues showed that pY39 α-syn is detected in the brains of healthy individuals and those with PD. However, only c-Abl protein levels were found to be upregulated in PD brains. Interestingly, nilotinib, a specific inhibitor of c-Abl kinase activity, induces α-syn protein degradation via the autophagy and proteasome pathways, whereas the overexpression of α-syn in the rat midbrains enhances c-Abl expression. Together, these data suggest that changes in c-Abl expression, activation and/or c-Abl-mediated phosphorylation of Y39 play a role in regulating α-syn clearance and contribute to the pathogenesis of PD.
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Dean KE, Fields A, Geer MJ, King EC, Lynch BT, Manohar RR, McCall JR, Palozola KC, Zhang Y, Liebl EC. An allele of sequoia dominantly enhances a trio mutant phenotype to influence Drosophila larval behavior. PLoS One 2014; 8:e84149. [PMID: 24376789 PMCID: PMC3869853 DOI: 10.1371/journal.pone.0084149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 11/20/2013] [Indexed: 11/18/2022] Open
Abstract
The transition of Drosophila third instar larvae from feeding, photo-phobic foragers to non-feeding, photo-neutral wanderers is a classic behavioral switch that precedes pupariation. The neuronal network responsible for this behavior has recently begun to be defined. Previous genetic analyses have identified signaling components for food and light sensory inputs and neuropeptide hormonal outputs as being critical for the forager to wanderer transition. Trio is a Rho-Guanine Nucleotide Exchange Factor integrated into a variety of signaling networks including those governing axon pathfinding in early development. Sequoia is a pan-neuronally expressed zinc-finger transcription factor that governs dendrite and axon outgrowth. Using pre-pupal lethality as an endpoint, we have screened for dominant second-site enhancers of a weakly lethal trio mutant background. In these screens, an allele of sequoia has been identified. While these mutants have no obvious disruption of embryonic central nervous system architecture and survive to third instar larvae similar to controls, they retain forager behavior and thus fail to pupariate at high frequency.
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Affiliation(s)
- Kathryn E. Dean
- Department of Biology, Denison University, Talbot Hall of Biological Science, Granville, Ohio, United States of America
| | - April Fields
- Department of Biology, Denison University, Talbot Hall of Biological Science, Granville, Ohio, United States of America
| | - Marcus J. Geer
- Department of Biology, Denison University, Talbot Hall of Biological Science, Granville, Ohio, United States of America
| | - Eric C. King
- Department of Biology, Denison University, Talbot Hall of Biological Science, Granville, Ohio, United States of America
| | - Brian T. Lynch
- Department of Biology, Denison University, Talbot Hall of Biological Science, Granville, Ohio, United States of America
| | - Rohan R. Manohar
- Department of Biology, Denison University, Talbot Hall of Biological Science, Granville, Ohio, United States of America
| | - Julianne R. McCall
- Department of Biology, Denison University, Talbot Hall of Biological Science, Granville, Ohio, United States of America
| | - Katherine C. Palozola
- Department of Biology, Denison University, Talbot Hall of Biological Science, Granville, Ohio, United States of America
| | - Yan Zhang
- Department of Biology, Denison University, Talbot Hall of Biological Science, Granville, Ohio, United States of America
| | - Eric C. Liebl
- Department of Biology, Denison University, Talbot Hall of Biological Science, Granville, Ohio, United States of America
- * E-mail:
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30
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Habib MR, Ganea DA, Katz IK, Lamprecht R. ABL1 in thalamus is associated with safety but not fear learning. Front Syst Neurosci 2013; 7:5. [PMID: 23532861 PMCID: PMC3607794 DOI: 10.3389/fnsys.2013.00005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Accepted: 03/02/2013] [Indexed: 11/13/2022] Open
Abstract
In auditory fear conditioning a tone is paired with a footshock, establishing long lasting fear memory to the tone. In safety learning these stimuli are presented in an unpaired non-overlapping manner and enduring memories to the tone as a safety signal are formed. Although these paradigms utilize the same sensory stimuli different memories are formed leading to distinct behavioral outcome. In this study we aimed to explore whether fear conditioning and safety learning lead to different molecular changes in thalamic area that receives tone and shock inputs. Toward that end, we used antibody microarrays to detect changes in proteins levels in this brain region. The levels of ABL1, Bog, IL1B, and Tau proteins in thalamus were found to be lower in the group trained for safety learning compared to the fear conditioning group 6 h after training. The levels of these proteins were not different between safety learning and fear conditioning trained groups in auditory cortex. Western blot analysis revealed that the ABL1 protein level in thalamus is reduced specifically by safety learning but not fear conditioning when compared to naïve rats. These results show that safety learning leads to activation of auditory thalamus differently from fear conditioning and to a decrease in the level of ABL1 protein in this brain region. Reduction in ABL1 level in thalamus may affect neuronal processes, such as morphogenesis and synaptic efficacy shown to be intimately regulated by changes in this kinase level.
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Affiliation(s)
- Mouna R Habib
- Sagol Department of Neurobiology, Faculty of Natural Sciences, Center for Gene Manipulation in the Brain, Center for Brain and Behavior, University of Haifa Haifa, Israel
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Shen Y, Meiri K. GAP-43 dependency defines distinct effects of netrin-1 on cortical and spinal neurite outgrowth and directional guidance. Int J Dev Neurosci 2012; 31:11-20. [PMID: 23085079 DOI: 10.1016/j.ijdevneu.2012.10.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 09/18/2012] [Accepted: 10/08/2012] [Indexed: 10/27/2022] Open
Abstract
Growth-associated protein-43 (GAP-43) is a major nervous system protein whose phosphorylation by protein kinase C regulates growth cone responses to extracellular guidance cues via F-actin. GAP-43 is essential for axon pathfinding in both cortical afferents and efferents: when it is genetically deleted, somatosensory, auditory and visual somatotopic maps fail to form, and telencephalic commissural axons fail to cross the midline. Here we investigated whether the midline guidance cue netrin-1 depends on GAP-43 for its functions in neurite growth and guidance. We used 3-dimensional collagen gel co-cultures to show that both endogenous netrin-1, expressed by the spinal cord floor plate, and recombinant netrin-1, expressed by transfected COS7 cells, stimulate neurite outgrowth and chemotropic guidance of neocortical callosal axons. In contrast both were significantly inhibited in GAP-43 (-/-) neocortical callosal axons, mimicking the in vivo phenotype. Conversely, neither netrin-1-stimulated neurite outgrowth nor guidance of dorsal spinal cord commissure axons were affected when GAP-43 was absent, again consistent with in vivo phenotype but suggesting fundamental differences in how neocortical and spinal cord axons respond to netrin-1. In addition, differences in GAP-43 dependency also distinguished how ventrolateral cortical efferents respond to netrin-1: in contrast to callosal neurites, in which netrin-1 required GAP-43 in order to stimulate both outgrowth and guidance, in ventrolateral efferents, netrin-1 required GAP-43 only to stimulate outgrowth, but not guidance. Moreover, netrin-1 increased the numbers of both types of cortical, but not spinal neurites. The results demonstrate previously unappreciated diversity in how different classes of neurons respond to the same guidance cue.
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Affiliation(s)
- Yiping Shen
- Programs in Cell and Molecular Biology and Neuroscience, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA.
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32
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McShea MA, Schmidt KL, Dubuke ML, Baldiga CE, Sullender ME, Reis AL, Zhang S, O'Toole SM, Jeffers MC, Warden RM, Kenney AH, Gosselin J, Kuhlwein M, Hashmi SK, Stringham EG, Ryder EF. Abelson interactor-1 (ABI-1) interacts with MRL adaptor protein MIG-10 and is required in guided cell migrations and process outgrowth in C. elegans. Dev Biol 2012; 373:1-13. [PMID: 23022657 DOI: 10.1016/j.ydbio.2012.09.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 09/12/2012] [Accepted: 09/21/2012] [Indexed: 11/19/2022]
Abstract
Directed cell migration and process outgrowth are vital to proper development of many metazoan tissues. These processes are dependent on reorganization of the actin cytoskeleton in response to external guidance cues. During development of the nervous system, the MIG-10/RIAM/Lamellipodin (MRL) signaling proteins are thought to transmit positional information from surface guidance cues to the actin polymerization machinery, and thus to promote polarized outgrowth of axons. In C. elegans, mutations in the MRL family member gene mig-10 result in animals that have defects in axon guidance, neuronal migration, and the outgrowth of the processes or 'canals' of the excretory cell, which is required for osmoregulation in the worm. In addition, mig-10 mutant animals have recently been shown to have defects in clustering of vesicles at the synapse. To determine additional molecular partners of MIG-10, we conducted a yeast two-hybrid screen using isoform MIG-10A as bait and isolated Abelson-interactor protein-1 (ABI-1). ABI-1, a downstream target of Abl non-receptor tyrosine kinase, is a member of the WAVE regulatory complex (WRC) involved in the initiation of actin polymerization. Further analysis using a co-immunoprecipitation system confirmed the interaction of MIG-10 and ABI-1 and showed that it requires the SH3 domain of ABI-1. Single mutants for mig-10 and abi-1 displayed similar phenotypes of incomplete migration of the ALM neurons and truncated outgrowth of the excretory cell canals, suggesting that the ABI-1/MIG-10 interaction is relevant in vivo. Cell autonomous expression of MIG-10 isoforms rescued both the neuronal migration and the canal outgrowth defects, showing that MIG-10 functions autonomously in the ALM neurons and the excretory cell. These results suggest that MIG-10 and ABI-1 interact physically to promote cell migration and process outgrowth in vivo. In the excretory canal, ABI-1 is thought to act downstream of UNC-53/NAV2, linking this large scaffolding protein to actin polymerization during excretory canal outgrowth. abi-1(RNAi) enhanced the excretory canal truncation observed in mig-10 mutants, while double mutant analysis between unc-53 and mig-10 showed no increased truncation of the posterior canal beyond that observed in mig-10 mutants. Morphological analysis of mig-10 and unc-53 mutants showed that these genes regulate canal diameter as well as its length, suggesting that defective lumen formation may be linked to the ability of the excretory canal to grow out longitudinally. Taken together, our results suggest that MIG-10, UNC-53, and ABI-1 act sequentially to mediate excretory cell process outgrowth.
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Affiliation(s)
- Molly A McShea
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA.
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Fang Y, Bonini NM. Axon degeneration and regeneration: insights from Drosophila models of nerve injury. Annu Rev Cell Dev Biol 2012; 28:575-97. [PMID: 22831639 DOI: 10.1146/annurev-cellbio-101011-155836] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Axon degeneration is the pivotal pathological event of acute traumatic neural injury as well as many chronic neurodegenerative diseases. It is an active cellular program and yet molecularly distinct from cell death. Much effort is devoted toward understanding the nature of axon degeneration and promoting axon regeneration. However, the fundamental mechanisms of self-destruction of damaged axons remain unclear, and there are still few treatments for traumatic brain injury (TBI) or spinal cord injury (SCI). Genetically approachable model organisms such as Drosophila melanogaster, the fruit fly, have proven exceptionally successful in modeling human neurodegenerative diseases. More recently, this success has been extended into the field of acute axon injury and regeneration. In this review, we discuss recent findings, focusing on how these models hold promise for accelerating mechanistic insight into axon injury and identifying potential therapeutic targets for TBI and SCI.
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Affiliation(s)
- Yanshan Fang
- Howard Hughes Medical Institute and Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA.
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34
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Liu XF, Bera TK, Kahue C, Escobar T, Fei Z, Raciti GA, Pastan I. ANKRD26 and its interacting partners TRIO, GPS2, HMMR and DIPA regulate adipogenesis in 3T3-L1 cells. PLoS One 2012; 7:e38130. [PMID: 22666460 PMCID: PMC3364200 DOI: 10.1371/journal.pone.0038130] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 05/04/2012] [Indexed: 01/04/2023] Open
Abstract
Partial inactivation of the Ankyrin repeat domain 26 (Ankrd26) gene causes obesity and diabetes in mice and increases spontaneous and induced adipogenesis in mouse embryonic fibroblasts. However, it is not yet known how the Ankrd26 protein carries out its biological functions. We identified by yeast two-hybrid and immunoprecipitation assays the triple functional domain protein (TRIO), the G protein pathway suppressor 2 (GPS2), the delta-interacting protein A (DIPA) and the hyaluronan-mediated motility receptor (HMMR) as ANKRD26 interacting partners. Adipogenesis of 3T3-L1 cells was increased by selective down-regulation of Ankrd26, Trio, Gps2, Hmmr and Dipa. Furthermore, GPS2 and DIPA, which are normally located in the nucleus, were translocated to the cytoplasm, when the C-terminus of ANKRD26 was introduced into these cells. These findings provide biochemical evidence that ANKRD26, TRIO, GPS2 and HMMR are novel and important regulators of adipogenesis and identify new targets for the modulation of adipogenesis.
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Affiliation(s)
- Xiu-Fen Liu
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Tapan K. Bera
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Charissa Kahue
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Thelma Escobar
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Zhaoliang Fei
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Gregory A. Raciti
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Ira Pastan
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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35
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Tamada M, Farrell DL, Zallen JA. Abl regulates planar polarized junctional dynamics through β-catenin tyrosine phosphorylation. Dev Cell 2012; 22:309-19. [PMID: 22340496 PMCID: PMC3327890 DOI: 10.1016/j.devcel.2011.12.025] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 11/17/2011] [Accepted: 12/30/2011] [Indexed: 01/11/2023]
Abstract
Interactions between epithelial cells are mediated by adherens junctions that are dynamically regulated during development. Here we show that the turnover of β-catenin is increased at cell interfaces that are targeted for disassembly during Drosophila axis elongation. The Abl tyrosine kinase is concentrated at specific planar junctions and is necessary for polarized β-catenin localization and dynamics. abl mutant embryos have decreased β-catenin turnover at shrinking edges, and these defects are accompanied by a reduction in multicellular rosette formation and axis elongation. Abl promotes β-catenin phosphorylation on the conserved tyrosine 667 and expression of an unphosphorylatable β-catenin mutant recapitulates the defects of abl mutants. Notably, a phosphomimetic β-catenin(Y667E) mutation is sufficient to increase β-catenin turnover and rescue axis elongation in abl deficient embryos. These results demonstrate that the asymmetrically localized Abl tyrosine kinase directs planar polarized junctional remodeling during Drosophila axis elongation through the tyrosine phosphorylation of β-catenin.
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Affiliation(s)
- Masako Tamada
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10065 USA
| | - Dene L. Farrell
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10065 USA
| | - Jennifer A. Zallen
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10065 USA
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36
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Abstract
Polymerization of actin, which is crucial for functions such as cell migration, membrane ruffling, cytokinesis, and endocytosis, must be tightly regulated in order to preserve an adequate supply of free actin monomers to respond to changing external conditions. The paper will describe mechanisms by which F-actin feeds back on its own assembly, thus regulating itself. I will present the experimental evidence for such feedback terms, discuss their use in current models of actin dynamics in cells, and present preliminary calculations for the role of feedback in transient endocytic actin patches. These calculations suggest a partial homeostasis of F-actin, in which the F-actin peak height depends only weakly on the actin filament nucleation rate.
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Wang Y, Yang F, Fu Y, Huang X, Wang W, Jiang X, Gritsenko MA, Zhao R, Monore ME, Pertz OC, Purvine SO, Orton DJ, Jacobs JM, Camp DG, Smith RD, Klemke RL. Spatial phosphoprotein profiling reveals a compartmentalized extracellular signal-regulated kinase switch governing neurite growth and retraction. J Biol Chem 2011; 286:18190-201. [PMID: 21454597 DOI: 10.1074/jbc.m111.236133] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Brain development and spinal cord regeneration require neurite sprouting and growth cone navigation in response to extension and collapsing factors present in the extracellular environment. These external guidance cues control neurite growth cone extension and retraction processes through intracellular protein phosphorylation of numerous cytoskeletal, adhesion, and polarity complex signaling proteins. However, the complex kinase/substrate signaling networks that mediate neuritogenesis have not been investigated. Here, we compare the neurite phosphoproteome under growth and retraction conditions using neurite purification methodology combined with mass spectrometry. More than 4000 non-redundant phosphorylation sites from 1883 proteins have been annotated and mapped to signaling pathways that control kinase/phosphatase networks, cytoskeleton remodeling, and axon/dendrite specification. Comprehensive informatics and functional studies revealed a compartmentalized ERK activation/deactivation cytoskeletal switch that governs neurite growth and retraction, respectively. Our findings provide the first system-wide analysis of the phosphoprotein signaling networks that enable neurite growth and retraction and reveal an important molecular switch that governs neuritogenesis.
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Affiliation(s)
- Yingchun Wang
- Department of Pathology and Moores Cancer Center, University of California, San Diego, La Jolla, California 92093, USA
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Hallock PT, Xu CF, Park TJ, Neubert TA, Curran T, Burden SJ. Dok-7 regulates neuromuscular synapse formation by recruiting Crk and Crk-L. Genes Dev 2011; 24:2451-61. [PMID: 21041412 DOI: 10.1101/gad.1977710] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Agrin, released by motor neurons, promotes neuromuscular synapse formation by stimulating MuSK, a receptor tyrosine kinase expressed in skeletal muscle. Phosphorylated MuSK recruits docking protein-7 (Dok-7), an adaptor protein that is expressed selectively in muscle. In the absence of Dok-7, neuromuscular synapses fail to form, and mutations that impair Dok-7 are a major cause of congenital myasthenia in humans. How Dok-7 stimulates synaptic differentiation is poorly understood. Once recruited to MuSK, Dok-7 directly stimulates MuSK kinase activity. This unusual activity of an adapter protein is mediated by the N-terminal region of Dok-7, whereas most mutations that cause congenital myasthenia truncate the C-terminal domain. Here, we demonstrate that Dok-7 also functions downstream from MuSK, and we identify the proteins that are recruited to the C-terminal domain of Dok-7. We show that Agrin stimulates phosphorylation of two tyrosine residues in the C-terminal domain of Dok-7, which leads to recruitment of two adapter proteins: Crk and Crk-L. Furthermore, we show that selective inactivation of Crk and Crk-L in skeletal muscle leads to severe defects in neuromuscular synapses in vivo, revealing a critical role for Crk and Crk-L downstream from Dok-7 in presynaptic and postsynaptic differentiation.
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Affiliation(s)
- Peter T Hallock
- Molecular Neurobiology Program, Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, New York 10016, USA
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Yaba A, Kayisli UA, Johnson J, Demir R, Demir N. The Abelson tyrosine kinase (c-Abl) expression on the mouse uterus and placenta during gestational period. J Mol Histol 2011; 42:91-6. [PMID: 21249431 DOI: 10.1007/s10735-011-9310-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Accepted: 01/06/2011] [Indexed: 10/18/2022]
Abstract
c-Abl is a protein tyrosine kinase which has very important roles in signal transduction, control of the cell cycle, cell motility, proliferation, and inhibition of apoptosis. We hypothesized that c-Abl may play an important role on uterine remodeling during pre-receptive, receptive and non-receptive endometrium. Our aim is to investigate the expression of c-Abl protein tyrosine kinase in uterine remodeling and placental development in mouse gestational stage. We performed c-Abl immunohistochemistry on mouse uterine tissue sections on days 1-9, 11, 13, and 15 of pregnancy. c-Abl was highly upregulated in the uterine luminal epithelium and other endometrial structures including glands and blood vessels in pre-receptive and receptive endometrium. Therefore these results demonstrate a role for c-Abl in uterine remodeling during decidualization, implantation, and placentation throughout gestation.
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Affiliation(s)
- Aylin Yaba
- Department of Histology and Embryology, Akdeniz University Faculty of Medicine, Campus, 07070, Antalya, Turkey
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40
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Spatial and temporal expression of vasodilator‐stimulated phosphoprotein (VASP) in fetal and adult human cerebral cortex. Int J Dev Neurosci 2010; 29:131-6. [DOI: 10.1016/j.ijdevneu.2010.12.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 12/03/2010] [Accepted: 12/07/2010] [Indexed: 11/22/2022] Open
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Parallel genetic and proteomic screens identify Msps as a CLASP-Abl pathway interactor in Drosophila. Genetics 2010; 185:1311-25. [PMID: 20498300 DOI: 10.1534/genetics.110.115626] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Regulation of cytoskeletal structure and dynamics is essential for multiple aspects of cellular behavior, yet there is much to learn about the molecular machinery underlying the coordination between the cytoskeleton and its effector systems. One group of proteins that regulate microtubule behavior and its interaction with other cellular components, such as actin-regulatory proteins and transport machinery, is the plus-end tracking proteins (MT+TIPs). In particular, evidence suggests that the MT+TIP, CLASP, may play a pivotal role in the coordination of microtubules with other cellular structures in multiple contexts, although the molecular mechanism by which it functions is still largely unknown. To gain deeper insight into the functional partners of CLASP, we conducted parallel genetic and proteome-wide screens for CLASP interactors in Drosophila melanogaster. We identified 36 genetic modifiers and 179 candidate physical interactors, including 13 that were identified in both data sets. Grouping interactors according to functional classifications revealed several categories, including cytoskeletal components, signaling proteins, and translation/RNA regulators. We focused our initial investigation on the MT+TIP Minispindles (Msps), identified among the cytoskeletal effectors in both genetic and proteomic screens. Here, we report that Msps is a strong modifier of CLASP and Abl in the retina. Moreover, we show that Msps functions during axon guidance and antagonizes both CLASP and Abl activity. Our data suggest a model in which CLASP and Msps converge in an antagonistic balance in the Abl signaling pathway.
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Singh J, Aaronson SA, Mlodzik M. Drosophila Abelson kinase mediates cell invasion and proliferation through two distinct MAPK pathways. Oncogene 2010; 29:4033-45. [PMID: 20453880 PMCID: PMC2919309 DOI: 10.1038/onc.2010.155] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The Abelson (Abl) family of non-receptor tyrosine kinases plays important role in cell morphogenesis, motility and proliferation. Although the function of Abl has been extensively studied in leukemia, its role in epithelial cell invasion remains obscure. Using the Drosophila wing epithelium as an in-vivo model system, we demonstrate that overexpression (activation) of Drosophila Abl (dAbl) causes loss of epithelial apical/basal cell polarity and secretion of matrix metalloproteinases, resulting in a cellular invasion and apoptosis. Our in vivo data indicate that dAbl acts downstream of the Src kinases, which are known regulators of cell adhesion and invasion. Downstream of dAbl, Rac GTPases activate two distinct MAPK pathways: JNK signaling (required for cell invasion and apoptosis) and ERK signaling (inducing cell proliferation). Activated Abl also increases the activity of Src members through a positive feedback loop leading to signal amplification. Thus targeting Src-Abl, using available dual inhibitors, could be of therapeutic importance in tumor cell metastasis.
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Affiliation(s)
- J Singh
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, NY 10029, USA
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Impact of actin filament stabilization on adult hippocampal and olfactory bulb neurogenesis. J Neurosci 2010; 30:3419-31. [PMID: 20203201 DOI: 10.1523/jneurosci.4231-09.2010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Rearrangement of the actin cytoskeleton is essential for dynamic cellular processes. Decreased actin turnover and rigidity of cytoskeletal structures have been associated with aging and cell death. Gelsolin is a Ca(2+)-activated actin-severing protein that is widely expressed throughout the adult mammalian brain. Here, we used gelsolin-deficient (Gsn(-/-)) mice as a model system for actin filament stabilization. In Gsn(-/-) mice, emigration of newly generated cells from the subventricular zone into the olfactory bulb was slowed. In vitro, gelsolin deficiency did not affect proliferation or neuronal differentiation of adult neural progenitors cells (NPCs) but resulted in retarded migration. Surprisingly, hippocampal neurogenesis was robustly induced by gelsolin deficiency. The ability of NPCs to intrinsically sense excitatory activity and thereby implement coupling between network activity and neurogenesis has recently been established. Depolarization-induced [Ca(2+)](i) increases and exocytotic neurotransmitter release were enhanced in Gsn(-/-) synaptosomes. Importantly, treatment of Gsn(-/-) synaptosomes with mycotoxin cytochalasin D, which, like gelsolin, produces actin disassembly, decreased enhanced Ca(2+) influx and subsequent exocytotic norepinephrine release to wild-type levels. Similarly, depolarization-induced glutamate release from Gsn(-/-) brain slices was increased. Furthermore, increased hippocampal neurogenesis in Gsn(-/-) mice was associated with a special microenvironment characterized by enhanced density of perfused vessels, increased regional cerebral blood flow, and increased endothelial nitric oxide synthase (NOS-III) expression in hippocampus. Together, reduced filamentous actin turnover in presynaptic terminals causes increased Ca(2+) influx and, subsequently, elevated exocytotic neurotransmitter release acting on neural progenitors. Increased neurogenesis in Gsn(-/-) hippocampus is associated with a special vascular niche for neurogenesis.
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Simonova OB, Burdina NV. Morphogenetic movement of cells in embryogenesis of Drosophila melanogaster: Mechanism and genetic control. Russ J Dev Biol 2009. [DOI: 10.1134/s1062360409050038] [Citation(s) in RCA: 3] [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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Lin TY, Huang CH, Kao HH, Liou GG, Yeh SR, Cheng CM, Chen MH, Pan RL, Juang JL. Abi plays an opposing role to Abl in Drosophila axonogenesis and synaptogenesis. Development 2009; 136:3099-107. [PMID: 19675132 DOI: 10.1242/dev.033324] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Abl tyrosine kinase (Abl) regulates axon guidance by modulating actin dynamics. Abelson interacting protein (Abi), originally identified as a kinase substrate of Abl, also plays a key role in actin dynamics, yet its role with respect to Abl in the developing nervous system remains unclear. Here we show that mutations in abi disrupt axonal patterning in the developing Drosophila central nervous system (CNS). However, reducing abi gene dosage by half substantially rescues Abl mutant phenotypes in pupal lethality, axonal guidance defects and locomotion deficits. Moreover, we show that mutations in Abl increase synaptic growth and spontaneous synaptic transmission frequency at the neuromuscular junction. Double heterozygosity for abi and enabled (ena) also suppresses the synaptic overgrowth phenotypes of Abl mutants, suggesting that Abi acts cooperatively with Ena to antagonize Abl function in synaptogenesis. Intriguingly, overexpressing Abi or Ena alone in cultured cells dramatically redistributed peripheral F-actin to the cytoplasm, with aggregates colocalizing with Abi and/or Ena, and resulted in a reduction in neurite extension. However, co-expressing Abl with Abi or Ena redistributed cytoplasmic F-actin back to the cell periphery and restored bipolar cell morphology. These data suggest that abi and Abl have an antagonistic interaction in Drosophila axonogenesis and synaptogenesis, which possibly occurs through the modulation of F-actin reorganization.
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Affiliation(s)
- Tzu-Yang Lin
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli 35053, Taiwan
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Xin X, Rabiner CA, Mains RE, Eipper BA. Kalirin12 interacts with dynamin. BMC Neurosci 2009; 10:61. [PMID: 19534784 PMCID: PMC2703648 DOI: 10.1186/1471-2202-10-61] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Accepted: 06/17/2009] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Guanine nucleotide exchange factors (GEFs) and their target Rho GTPases regulate cytoskeletal changes and membrane trafficking. Dynamin, a large force-generating GTPase, plays an essential role in membrane tubulation and fission in cells. Kalirin12, a neuronal RhoGEF, is found in growth cones early in development and in dendritic spines later in development. RESULTS The IgFn domain of Kalirin12, not present in other Kalirin isoforms, binds dynamin1 and dynamin2. An inactivating mutation in the GTPase domain of dynamin diminishes this interaction and the isolated GTPase domain of dynamin retains the ability to bind Kalirin12. Co-immunoprecipitation demonstrates an interaction of Kalirin12 and dynamin2 in embryonic brain. Purified recombinant Kalirin-IgFn domain inhibits the ability of purified rat brain dynamin to oligomerize in response to the presence of liposomes containing phosphatidylinositol-4,5-bisphosphate. Consistent with this, expression of exogenous Kalirin12 or its IgFn domain in PC12 cells disrupts clathrin-mediated transferrin endocytosis. Similarly, expression of exogenous Kalirin12 disrupts transferrin endocytosis in cortical neurons. Expression of Kalirin7, a shorter isoform which lacks the IgFn domain, was previously shown to inhibit clathrin-mediated endocytosis; the GTPase domain of dynamin does not interact with Kalirin7. CONCLUSION Kalirin12 may play a role in coordinating Rho GTPase-mediated changes in the actin cytoskeleton with dynamin-mediated changes in membrane trafficking.
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Affiliation(s)
- Xiaonan Xin
- Neuroscience Department, University of Connecticut Health Center, Farmington, USA.
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Jacob M, Todd LA, Majumdar RS, Li Y, Yamamoto KI, Puré E. Endogenous cAbl regulates receptor endocytosis. Cell Signal 2009; 21:1308-16. [PMID: 19344757 DOI: 10.1016/j.cellsig.2009.03.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 03/13/2009] [Accepted: 03/15/2009] [Indexed: 01/17/2023]
Abstract
There are two key processes underlying ligand-induced receptor endocytosis: receptor ubiquitylation and remodeling of the actin cytoskeleton. Tyrosine kinases play critical roles in both receptor endocytosis and actin reorganization. Interestingly, members of the Abl family are the only known tyrosine kinases that possess an actin-binding domain and thus have the potential to directly regulate the actin cytoskeleton. However, the role of non-transforming cAbl in receptor endocytosis remains undefined. We report that cAbl promotes ligand-induced antigen receptor endocytosis in B lymphocytes. We show that pharmacologic inhibition or genetic deletion of cAbl causes a defect in tyrosine phosphorylation of the cytoskeletal adapter CrkII. cAbl inhibition or ablation also impairs Rac activation downstream of CrkII, as well as antigen receptor capping and endocytosis. Although phosphorylation of CrkII has been suggested to maintain it in a closed inactive conformation, we demonstrate that it is in fact essential for the activation of Rac. On the other hand, association of CrkII with cCbl, a key mediator of receptor ubiquitylation, does not require CrkII phosphorylation and is cAbl-independent. Phosphorylation of cCbl itself is also cAbl-independent. Our results thus indicate that CrkII links receptor engagement to cytoskeletal remodeling by coupling cCbl- and cAbl-mediated signaling pathways that cooperatively regulate ligand-induced receptor endocytosis.
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Affiliation(s)
- Michele Jacob
- The Wistar Institute, 3601 Spruce Street, Philadelphia, Pennsylvania 19104-4268, USA.
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Beazely MA, Weerapura M, MacDonald JF. Abelson tyrosine kinase links PDGFbeta receptor activation to cytoskeletal regulation of NMDA receptors in CA1 hippocampal neurons. Mol Brain 2008; 1:20. [PMID: 19077273 PMCID: PMC2651131 DOI: 10.1186/1756-6606-1-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Accepted: 12/12/2008] [Indexed: 01/12/2023] Open
Abstract
Background We have previously demonstrated that PDGF receptor activation indirectly inhibits N-methyl-D-aspartate (NMDA) currents by modifying the cytoskeleton. PDGF receptor ligand is also neuroprotective in hippocampal slices and cultured neurons. PDGF receptors are tyrosine kinases that control a variety of signal transduction pathways including those mediated by PLCγ. In fibroblasts Src and another non-receptor tyrosine kinase, Abelson kinase (Abl), control PDGF receptor regulation of cytoskeletal dynamics. The mechanism whereby PDGF receptor regulates cytoskeletal dynamics in central neurons remains poorly understood. Results Intracellular applications of active Abl, but not heat-inactivated Abl, decreased NMDA-evoked currents in isolated hippocampal neurons. This mimics the effects of PDGF receptor activation in these neurons. The Abl kinase inhibitor, STI571, blocked the inhibition of NMDA currents by Abl. We demonstrate that PDGF receptors can activate Abl kinase in hippocampal neurons via mechanisms similar to those observed previously in fibroblasts. Furthermore, PDGFβ receptor activation alters the subcellular localization of Abl. Abl kinase is linked to actin cytoskeletal dynamics in many systems. We show that the inhibition of NMDA receptor currents by Abl kinase is blocked by the inclusion of the Rho kinase inhibitor, Y-27632, and that activation of Abl correlates with an increase in ROCK tyrosine phosphorylation. Conclusion This study demonstrates that PDGFβ receptors act via an interaction with Abl kinase and Rho kinase to regulated cytoskeletal regulation of NMDA receptor channels in CA1 pyramidal neurons.
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Dobbins GC, Luo S, Yang Z, Xiong WC, Mei L. alpha-Actinin interacts with rapsyn in agrin-stimulated AChR clustering. Mol Brain 2008; 1:18. [PMID: 19055765 PMCID: PMC2621155 DOI: 10.1186/1756-6606-1-18] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Accepted: 12/03/2008] [Indexed: 11/10/2022] Open
Abstract
AChR is concentrated at the postjunctional membrane at the neuromuscular junction. However, the underlying mechanism is unclear. We show that α-actinin, a protein known to cross-link F-actin, interacts with rapsyn, a scaffold protein essential for neuromuscular junction formation. α-Actinin, rapsyn, and surface AChR form a ternary complex. Moreover, the rapsyn-α-actinin interaction is increased by agrin, a factor known to stimulate AChR clustering. Downregulation of α-actinin expression inhibits agrin-mediated AChR clustering. Furthermore, the rapsyn-α-actinin interaction can be disrupted by inhibiting Abl and by cholinergic stimulation. Together these results indicate a role for α-actinin in AChR clustering.
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Affiliation(s)
- G Clement Dobbins
- Institute of Molecular Medicine and Genetics, Department of Neurobiology, Medical College of Georgia, Augusta, Georgia 30912, USA.
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Characterization of EVL-I as a protein kinase D substrate. Cell Signal 2008; 21:282-92. [PMID: 19000756 DOI: 10.1016/j.cellsig.2008.10.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2008] [Revised: 10/15/2008] [Accepted: 10/22/2008] [Indexed: 11/21/2022]
Abstract
EVL-I is a splice variant of EVL (Ena/VASP like protein), whose in vivo function and regulation are still poorly understood. We found that Protein Kinase D (PKD) interacts in vitro and in vivo with EVL-I and phosphorylates EVL-I in a 21 amino acid alternately-included insert in the EVH2 domain. Following knockdown of the capping protein CPbeta and spreading on laminin, phosphorylated EVL-I can support filopodia formation and the phosphorylated EVL-I is localized at filopodial tips. Furthermore, we found that the lamellipodial localization of EVL-I is unaffected by phosphorylation, but that impairment of EVL-I phosphorylation is associated with ruffling of lamellipodia upon PDBu stimulation. Besides the lamellipodial and filopodial localization of phosphorylated EVL-I in fibroblasts, we determined that EVL-I is hyperphosphorylated and localized in the cell-cell contacts of certain breast cancer cells and mouse embryo keratinocytes. Taken together, our results show that phosphorylated EVL-I is present in lamellipodia, filopodia and cell-cell contacts and suggest the existence of signaling pathways that may affect EVL-I via phosphorylation of its EVH2 domain.
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