1
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Holley CL, Emming S, Monteleone MM, Mellacheruvu M, Kenney KM, Lawrence GMEP, Coombs JR, Burgener SS, Schroder K. The septin modifier, forchlorfenuron, activates NLRP3 via a potassium-independent mitochondrial axis. Cell Chem Biol 2024; 31:962-972.e4. [PMID: 38759620 DOI: 10.1016/j.chembiol.2024.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Revised: 04/07/2024] [Accepted: 04/19/2024] [Indexed: 05/19/2024]
Abstract
The Nod-like receptor protein 3 (NLRP3) inflammasome is activated by stimuli that induce perturbations in cell homeostasis, which commonly converge on cellular potassium efflux. NLRP3 has thus emerged as a sensor for ionic flux. Here, we identify forchlorfenuron (FCF) as an inflammasome activator that triggers NLRP3 signaling independently of potassium efflux. FCF triggers the rearrangement of septins, key cytoskeletal proteins that regulate mitochondrial function. We report that FCF triggered the rearrangement of SEPT2 into tubular aggregates and stimulated SEPT2-independent NLRP3 inflammasome signaling. Similar to imiquimod, FCF induced the collapse of the mitochondrial membrane potential and mitochondrial respiration. FCF thereby joins the imidazoquinolines as a structurally distinct class of molecules that triggers NLRP3 inflammasome signaling independent of potassium efflux, likely by inducing mitochondrial damage.
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Affiliation(s)
- Caroline L Holley
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Stefan Emming
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Mercedes M Monteleone
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Manasa Mellacheruvu
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kirsten M Kenney
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Grace M E P Lawrence
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jared R Coombs
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Sabrina S Burgener
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kate Schroder
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
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2
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Dorskind JM, Sudarsanam S, Hand RA, Ziak J, Amoah-Dankwah M, Guzman-Clavel L, Soto-Vargas JL, Kolodkin AL. Drebrin Regulates Collateral Axon Branching in Cortical Layer II/III Somatosensory Neurons. J Neurosci 2023; 43:7745-7765. [PMID: 37798130 PMCID: PMC10648559 DOI: 10.1523/jneurosci.0553-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 09/19/2023] [Accepted: 10/02/2023] [Indexed: 10/07/2023] Open
Abstract
Proper cortical lamination is essential for cognition, learning, and memory. Within the somatosensory cortex, pyramidal excitatory neurons elaborate axon collateral branches in a laminar-specific manner that dictates synaptic partners and overall circuit organization. Here, we leverage both male and female mouse models, single-cell labeling and imaging approaches to identify intrinsic regulators of laminar-specific collateral, also termed interstitial, axon branching. We developed new approaches for the robust, sparse, labeling of Layer II/III pyramidal neurons to obtain single-cell quantitative assessment of axon branch morphologies. We combined these approaches with cell-autonomous loss-of-function (LOF) and overexpression (OE) manipulations in an in vivo candidate screen to identify regulators of cortical neuron axon branch lamination. We identify a role for the cytoskeletal binding protein drebrin (Dbn1) in regulating Layer II/III cortical projection neuron (CPN) collateral axon branching in vitro LOF experiments show that Dbn1 is necessary to suppress the elongation of Layer II/III CPN collateral axon branches within Layer IV, where axon branching by Layer II/III CPNs is normally absent. Conversely, Dbn1 OE produces excess short axonal protrusions reminiscent of nascent axon collaterals that fail to elongate. Structure-function analyses implicate Dbn1S142 phosphorylation and Dbn1 protein domains known to mediate F-actin bundling and microtubule (MT) coupling as necessary for collateral branch initiation upon Dbn1 OE. Taken together, these results contribute to our understanding of the molecular mechanisms that regulate collateral axon branching in excitatory CPNs, a key process in the elaboration of neocortical circuit formation.SIGNIFICANCE STATEMENT Laminar-specific axon targeting is essential for cortical circuit formation. Here, we show that the cytoskeletal protein drebrin (Dbn1) regulates excitatory Layer II/III cortical projection neuron (CPN) collateral axon branching, lending insight into the molecular mechanisms that underlie neocortical laminar-specific innervation. To identify branching patterns of single cortical neurons in vivo, we have developed tools that allow us to obtain detailed images of individual CPN morphologies throughout postnatal development and to manipulate gene expression in these same neurons. Our results showing that Dbn1 regulates CPN interstitial axon branching both in vivo and in vitro may aid in our understanding of how aberrant cortical neuron morphology contributes to dysfunctions observed in autism spectrum disorder and epilepsy.
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Affiliation(s)
- Joelle M Dorskind
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins Kavli Neuroscience Discovery Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Sriram Sudarsanam
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins Kavli Neuroscience Discovery Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Randal A Hand
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins Kavli Neuroscience Discovery Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Jakub Ziak
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins Kavli Neuroscience Discovery Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Maame Amoah-Dankwah
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins Kavli Neuroscience Discovery Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Luis Guzman-Clavel
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins Kavli Neuroscience Discovery Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
- Summer Internship Program (NeuroSIP), Solomon H. Snyder Department of Neuroscience, Johns Hopkins Kavli Neuroscience Discovery Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - John Lee Soto-Vargas
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins Kavli Neuroscience Discovery Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
- Basic Science Institute-Summer Internship Program (BSI-SIP), Johns Hopkins Kavli Neuroscience Discovery Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Alex L Kolodkin
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins Kavli Neuroscience Discovery Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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3
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Suber Y, Alam MNA, Nakos K, Bhakt P, Spiliotis ET. Microtubule-associated septin complexes modulate kinesin and dynein motility with differential specificities. J Biol Chem 2023; 299:105084. [PMID: 37495111 PMCID: PMC10463263 DOI: 10.1016/j.jbc.2023.105084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 06/27/2023] [Accepted: 07/14/2023] [Indexed: 07/28/2023] Open
Abstract
Long-range membrane traffic is guided by microtubule-associated proteins and posttranslational modifications, which collectively comprise a traffic code. The regulatory principles of this code and how it orchestrates the motility of kinesin and dynein motors are largely unknown. Septins are a large family of GTP-binding proteins, which assemble into complexes that associate with microtubules. Using single-molecule in vitro motility assays, we tested how the microtubule-associated SEPT2/6/7, SEPT2/6/7/9, and SEPT5/7/11 complexes affect the motilities of the constitutively active kinesins KIF5C and KIF1A and the dynein-dynactin-bicaudal D (DDB) motor complex. We found that microtubule-associated SEPT2/6/7 is a potent inhibitor of DDB and KIF5C, preventing mainly their association with microtubules. SEPT2/6/7 also inhibits KIF1A by obstructing stepping along microtubules. On SEPT2/6/7/9-coated microtubules, KIF1A inhibition is dampened by SEPT9, which alone enhances KIF1A, showing that individual septin subunits determine the regulatory properties of septin complexes. Strikingly, SEPT5/7/11 differs from SEPT2/6/7, in permitting the motility of KIF1A and immobilizing DDB to the microtubule lattice. In hippocampal neurons, filamentous SEPT5 colocalizes with somatodendritic microtubules that underlie Golgi membranes and lack SEPT6. Depletion of SEPT5 disrupts Golgi morphology and polarization of Golgi ribbons into the shaft of somato-proximal dendrites, which is consistent with the tethering of DDB to microtubules by SEPT5/7/11. Collectively, these results suggest that microtubule-associated complexes have differential specificities in the regulation of the motility and positioning of microtubule motors. We posit that septins are an integral part of the microtubule-based code that spatially controls membrane traffic.
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Affiliation(s)
- Yani Suber
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Md Noor A Alam
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Konstantinos Nakos
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Priyanka Bhakt
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Elias T Spiliotis
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA.
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4
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Werner B, Yadav S. Phosphoregulation of the septin cytoskeleton in neuronal development and disease. Cytoskeleton (Hoboken) 2023; 80:275-289. [PMID: 36127729 PMCID: PMC10025170 DOI: 10.1002/cm.21728] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/13/2022] [Accepted: 09/12/2022] [Indexed: 11/06/2022]
Abstract
Septins are highly conserved GTP-binding proteins that oligomerize and form higher order structures. The septin cytoskeleton plays an important role in cellular organization, intracellular transport, and cytokinesis. Kinase-mediated phosphorylation of septins regulates various aspects of their function, localization, and dynamics. Septins are enriched in the mammalian nervous system where they contribute to neurodevelopment and neuronal function. Emerging research has implicated aberrant changes in septin cytoskeleton in several human diseases. The mechanisms through which aberrant phosphorylation by kinases contributes to septin dysfunction in neurological disorders are poorly understood and represent an important question for future research with therapeutic implications. This review summarizes the current state of knowledge of the diversity of kinases that interact with and phosphorylate mammalian septins, delineates how phosphoregulation impacts septin dynamics, and describes how aberrant septin phosphorylation contributes to neurological disorders.
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Affiliation(s)
- Bailey Werner
- Department of Pharmacology, University of Washington, Seattle, WA, United States
| | - Smita Yadav
- Department of Pharmacology, University of Washington, Seattle, WA, United States
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5
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Minegishi T, Kastian RF, Inagaki N. Mechanical regulation of synapse formation and plasticity. Semin Cell Dev Biol 2023; 140:82-89. [PMID: 35659473 DOI: 10.1016/j.semcdb.2022.05.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 05/10/2022] [Accepted: 05/17/2022] [Indexed: 01/28/2023]
Abstract
Dendritic spines are small protrusions arising from dendrites and constitute the major compartment of excitatory post-synapses. They change in number, shape, and size throughout life; these changes are thought to be associated with formation and reorganization of neuronal networks underlying learning and memory. As spines in the brain are surrounded by the microenvironment including neighboring cells and the extracellular matrix, their protrusion requires generation of force to push against these structures. In turn, neighboring cells receive force from protruding spines. Recent studies have identified BAR-domain proteins as being involved in membrane deformation to initiate spine formation. In addition, forces for dendritic filopodium extension and activity-induced spine expansion are generated through cooperation between actin polymerization and clutch coupling. On the other hand, force from expanding spines affects neurotransmitter release from presynaptic terminals. Here, we review recent advances in our understanding of the physical aspects of synapse formation and plasticity, mainly focusing on spine dynamics.
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Affiliation(s)
- Takunori Minegishi
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Ria Fajarwati Kastian
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan; Research Center for Genetic Engineering, National Research and Innovation Agency Republic of Indonesia, Cibinong, Bogor, Indonesia
| | - Naoyuki Inagaki
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.
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6
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Neuronal-specific septin-3 binds Atg8/LC3B, accumulates and localizes to autophagosomes during induced autophagy. Cell Mol Life Sci 2022; 79:471. [PMID: 35932293 PMCID: PMC9356936 DOI: 10.1007/s00018-022-04488-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 06/27/2022] [Accepted: 07/13/2022] [Indexed: 11/03/2022]
Abstract
In synapses that show signs of local apoptosis and mitochondrial stress and undergo neuro-immunological synapse pruning, an increase in the levels of the presynaptic protein, neuronal-specific septin-3 can be observed. Septin-3 is a member of the septin GTPase family with the ability to form multimers and contribute to the cytoskeleton. However, the function of septin-3 remains elusive. Here, we provide evidence that septin-3 is capable of binding the most-studied autophagy protein Atg8 homolog microtubule-associated protein 1 light chain 3B (LC3B), besides another homolog, GABA receptor-associated protein-like 2 (GABARAPL2). Moreover, we demonstrate that colocalization of septin-3 and LC3B increases upon chemical autophagy induction in primary neuronal cells. Septin-3 is accumulated in primary neurons upon autophagy enhancement or blockade, similar to autophagy proteins. Using electron microscopy, we also show that septin-3 localizes to LC3B positive membranes and can be found at mitochondria. However, colocalization results of septin-3 and the early mitophagy marker PTEN-induced kinase 1 (PINK1) do not support that binding of septin-3 to mitochondria is mitophagy related. We conclude that septin-3 correlates with synaptic/neuronal autophagy, binds Atg8 and localizes to autophagic membranes that can be enhanced with chemical autophagy induction. Based on our results, elevated septin-3 levels might indicate enhanced or impeded autophagy in neurons.
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7
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Zehtabian A, Müller PM, Goisser M, Obendorf L, Jänisch L, Hümpfer N, Rentsch J, Ewers H. Precise measurement of nanoscopic septin ring structures with deep learning-assisted quantitative superresolution microscopy. Mol Biol Cell 2022; 33:ar76. [PMID: 35594179 PMCID: PMC9635280 DOI: 10.1091/mbc.e22-02-0039] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The combination of image analysis and superresolution microscopy methods allows for unprecedented insight into the organization of macromolecular assemblies in cells. Advances in deep learning (DL)-based object recognition enable the automated processing of large amounts of data, resulting in high accuracy through averaging. However, while the analysis of highly symmetric structures of constant size allows for a resolution approaching the dimensions of structural biology, DL-based image recognition may introduce bias. This prohibits the development of readouts for processes that involve significant changes in size or shape of amorphous macromolecular complexes. Here we address this problem by using changes of septin ring structures in single molecule localization-based superresolution microscopy data as a paradigm. We identify potential sources of bias resulting from different training approaches by rigorous testing of trained models using real or simulated data covering a wide range of possible results. In a quantitative comparison of our models, we find that a trade-off exists between measurement accuracy and the range of recognized phenotypes. Using our thus verified models, we find that septin ring size can be explained by the number of subunits they are assembled from alone. Furthermore, we provide a new experimental system for the investigation of septin polymerization.
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Affiliation(s)
- Amin Zehtabian
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Paul Markus Müller
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Maximilian Goisser
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Leon Obendorf
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Lea Jänisch
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Nadja Hümpfer
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Jakob Rentsch
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Helge Ewers
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
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8
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Ageta-Ishihara N, Kinoshita M. Developmental and postdevelopmental roles of septins in the brain. Neurosci Res 2020; 170:6-12. [PMID: 33159992 DOI: 10.1016/j.neures.2020.08.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/21/2020] [Accepted: 08/23/2020] [Indexed: 11/25/2022]
Abstract
Morphogenetic processes during brain development and postdevelopmental remodeling of neural architecture depend on the exquisite interplay between the microtubule- and actin-based cytoskeletal systems. Accumulation of evidence indicates cooperative roles of another cytoskeletal system composed of the septin family. Here we overview experimental findings on mammalian septins and their hypothetical roles in the proliferation of neural progenitor cells, neurite development, synapse formation and regulations. The diverse, mostly unexpected phenotypes obtained from gain- and loss-of-function mutants point to unknown molecular network to be elucidated, which may underlie pathogenetic processes of infectious diseases and neuropsychiatric disorders in humans.
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Affiliation(s)
- Natsumi Ageta-Ishihara
- Division of Biological Science, Nagoya University Graduate School of Science, Furo, Chikusa, Nagoya 464-8602, Japan.
| | - Makoto Kinoshita
- Division of Biological Science, Nagoya University Graduate School of Science, Furo, Chikusa, Nagoya 464-8602, Japan.
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9
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Garge RK, Laurent JM, Kachroo AH, Marcotte EM. Systematic Humanization of the Yeast Cytoskeleton Discerns Functionally Replaceable from Divergent Human Genes. Genetics 2020; 215:1153-1169. [PMID: 32522745 PMCID: PMC7404242 DOI: 10.1534/genetics.120.303378] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 06/08/2020] [Indexed: 12/14/2022] Open
Abstract
Many gene families have been expanded by gene duplications along the human lineage, relative to ancestral opisthokonts, but the extent to which the duplicated genes function similarly is understudied. Here, we focused on structural cytoskeletal genes involved in critical cellular processes, including chromosome segregation, macromolecular transport, and cell shape maintenance. To determine functional redundancy and divergence of duplicated human genes, we systematically humanized the yeast actin, myosin, tubulin, and septin genes, testing ∼81% of human cytoskeletal genes across seven gene families for their ability to complement a growth defect induced by inactivation or deletion of the corresponding yeast ortholog. In five of seven families-all but α-tubulin and light myosin, we found at least one human gene capable of complementing loss of the yeast gene. Despite rescuing growth defects, we observed differential abilities of human genes to rescue cell morphology, meiosis, and mating defects. By comparing phenotypes of humanized strains with deletion phenotypes of their interaction partners, we identify instances of human genes in the actin and septin families capable of carrying out essential functions, but failing to fully complement the cytoskeletal roles of their yeast orthologs, thus leading to abnormal cell morphologies. Overall, we show that duplicated human cytoskeletal genes appear to have diverged such that only a few human genes within each family are capable of replacing the essential roles of their yeast orthologs. The resulting yeast strains with humanized cytoskeletal components now provide surrogate platforms to characterize human genes in simplified eukaryotic contexts.
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Affiliation(s)
- Riddhiman K Garge
- Center for Systems and Synthetic Biology, Department of Molecular Biosciences, The University of Texas at Austin, Texas 78712
| | - Jon M Laurent
- Center for Systems and Synthetic Biology, Department of Molecular Biosciences, The University of Texas at Austin, Texas 78712
- Institute for Systems Genetics, Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York 10016
| | - Aashiq H Kachroo
- The Department of Biology, Centre for Applied Synthetic Biology, Concordia University, Montreal, H4B 1R6 Quebec, Canada
| | - Edward M Marcotte
- Center for Systems and Synthetic Biology, Department of Molecular Biosciences, The University of Texas at Austin, Texas 78712
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10
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Andrianova IA, Ponomareva AA, Mordakhanova ER, Le Minh G, Daminova AG, Nevzorova TA, Rauova L, Litvinov RI, Weisel JW. In systemic lupus erythematosus anti-dsDNA antibodies can promote thrombosis through direct platelet activation. J Autoimmun 2020; 107:102355. [PMID: 31732191 PMCID: PMC10875727 DOI: 10.1016/j.jaut.2019.102355] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/28/2019] [Accepted: 10/30/2019] [Indexed: 12/20/2022]
Abstract
Systemic lupus erythematosus (SLE) is associated with a high risk of venous and arterial thrombosis, not necessarily associated with prothrombotic antiphospholipid antibodies (Abs). Alternatively, thrombosis may be due to an increased titer of anti-dsDNA Abs that presumably promote thrombosis via direct platelet activation. Here, we investigated effects of purified anti-dsDNA Abs from the blood of SLE patients, alone or in a complex with dsDNA, on isolated normal human platelets. We showed that anti-dsDNA Abs and anti-dsDNA Ab/dsDNA complexes induced strong platelet activation assessed by enhanced P-selectin expression and dramatic morphological and ultrastructural changes. Electron microscopy revealed a significantly higher percentage of platelets that lost their discoid shape, formed multiple filopodia and had a shrunken body when treated with anti-dsDNA Abs or anti-dsDNA Ab/dsDNA complexes compared with control samples. In addition, these platelets activated with anti-dsDNA Ab/dsDNA complexes typically contained a reduced number of secretory α-granules that grouped in the middle and often merged into a solid electron dense area. Many activated platelets released plasma membrane-derived microvesicles and/or fell apart into subcellular cytoplasmic fragments. Confocal microscopy revealed that platelets treated with anti-dsDNA Ab/dsDNA complex had a heterogeneous distribution of septin2 compared with the homogeneous distribution in control platelets. Structural perturbations were concomitant with mitochondrial depolarization and a decreased content of platelet ATP, indicating energetic exhaustion. Most of the biochemical and morphological changes in platelets induced by anti-dsDNA Abs and anti-dsDNA Ab/dsDNA complexes were prevented by pre-treatment with a monoclonal mAb against FcγRIIA. The aggregate of data indicates that anti-dsDNA Abs alone or in a complex with dsDNA strongly affect platelets via the FcγRIIA receptor. The immune activation of platelets with antinuclear Abs may comprise a prothrombotic mechanism underlying a high risk of thrombotic complications in patients with SLE.
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Affiliation(s)
- Izabella A Andrianova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation.
| | - Anastasiya A Ponomareva
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation; Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of the Russian Academy of Sciences, Kazan, Russian Federation.
| | - Elmira R Mordakhanova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation.
| | - Giang Le Minh
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation.
| | - Amina G Daminova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation; Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of the Russian Academy of Sciences, Kazan, Russian Federation.
| | - Tatiana A Nevzorova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation.
| | - Lubica Rauova
- The Children's Hospital of Philadelphia, Philadelphia, PA, USA; University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
| | - Rustem I Litvinov
- University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
| | - John W Weisel
- University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
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11
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Falk J, Boubakar L, Castellani V. Septin functions during neuro-development, a yeast perspective. Curr Opin Neurobiol 2019; 57:102-109. [DOI: 10.1016/j.conb.2019.01.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/09/2019] [Accepted: 01/13/2019] [Indexed: 12/24/2022]
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12
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Septin6 regulates cell growth and casein synthesis in dairy cow mammary epithelial cells via mTORC1 pathway. J DAIRY RES 2019; 86:181-187. [PMID: 31122298 DOI: 10.1017/s0022029919000268] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This research paper addresses the hypothesis that Septin6 is a key regulatory factor influencing amino acid (AA)-mediated cell growth and casein synthesis in dairy cow mammary epithelial cells (DCMECs). DCMECs were treated with absence of AA (AA-), restricted concentrations of AA (AAr) or normal concentrations of AA (AA+) for 24 h. Cell growth, expression of CSN2 and Septin6 were increased in response to AA supply. Overexpressing or inhibiting Septin6 demonstrated that cell growth, expression of CSN2, mTOR, p-mTOR, S6K1 and p-S6K1 were up-regulated by Septin6. Furthermore, overexpressing or inhibiting mTOR demonstrated that the increase in cell growth and expression of CSN2 in response to Septin6 overexpression were inhibited by mTOR inhibition, and vice versa. Our hypothesis was supported; we were able to show that Septin6 is an important positive factor for cell growth and casein synthesis, it up-regulates AA-mediated cell growth and casein synthesis through activating mTORC1 pathway in DCMECs.
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13
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Banko M, Mucha-Kruczynska I, Weise C, Heyd F, Ewers H. A homozygous genome-edited Sept2-EGFP fibroblast cell line. Cytoskeleton (Hoboken) 2019; 76:73-82. [PMID: 30924304 PMCID: PMC6593442 DOI: 10.1002/cm.21518] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 03/22/2019] [Accepted: 03/23/2019] [Indexed: 01/09/2023]
Abstract
Septins are a conserved, essential family of GTPases that interact with actin, microtubules, and membranes and form scaffolds and diffusion barriers in cells. Several of the 13 known mammalian septins assemble into nonpolar, multimeric complexes that can further polymerize into filamentous structures. While some GFP‐coupled septins have been described, overexpression of GFP‐tagged septins often leads to artifacts in localization and function. To overcome this ubiquitous problem, we have here generated a genome‐edited rat fibroblast cell line expressing Septin 2 (Sept2) coupled to enhanced green fluorescent protein (EGFP) from both chromosomal loci. We characterize these cells by genomic polymerase chain reaction (PCR) for genomic integration, by western blot and reverse transcriptase‐PCR for expression, by immunofluorescence and immunoprecipitation for the colocalization of septins with one another and cellular structures and for complex formation of different septins. By live cell imaging, proliferation and migration assays we investigate proper function of septins in these cells. We find that EGFP is incorporated into both chromosomal loci and only EGFP‐coupled Sept2 is expressed in homozygous cells. We find that endogenous Sept2‐EGFP exhibits expression levels, localization and incorporation into cellular septin complexes similar to the wt in these cells. The expression level of other septins is not perturbed and cell division and cell migration proceed normally. We expect our cell line to be a useful tool for the cell biology of septins, especially for quantitative biology.
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Affiliation(s)
- Monika Banko
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK.,Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Iwona Mucha-Kruczynska
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK.,Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Christoph Weise
- Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Florian Heyd
- Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Helge Ewers
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK.,Department of Biology, ETH Zürich, Zürich, Switzerland.,Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany
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14
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Honorat JA, Lopez-Chiriboga AS, Kryzer TJ, Fryer JP, Devine M, Flores A, Lennon VA, Pittock SJ, McKeon A. Autoimmune septin-5 cerebellar ataxia. NEUROLOGY-NEUROIMMUNOLOGY & NEUROINFLAMMATION 2018; 5:e474. [PMID: 29998156 PMCID: PMC6039209 DOI: 10.1212/nxi.0000000000000474] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/21/2018] [Indexed: 01/08/2023]
Abstract
Objective To report a form of autoimmune cerebellar ataxia in which antibodies target septin-5, a guanosine triphosphate (GTP)-binding neural protein involved in neurotransmitter exocytosis. Methods Archived sera and CSF specimens with unclassified synaptic antibodies were re-evaluated by tissue-based indirect immunofluorescence assay. Autoantigens were identified by Western blot and mass spectrometry. Recombinant protein assays (Western blot, cell based, and protein screening array) confirmed antigen specificity. Results Serum and CSF from 6 patients produced identical synaptic immunoglobulin G (IgG) staining patterns of synaptic regions (neuropil) of the mouse cerebrum and cerebellum. The molecular layer of the cerebellum and the thalamus demonstrated stronger immunoreactivity than the midbrain, hippocampus, cortex, and basal ganglia. The antigen revealed by mass spectrometry analysis of immunoprecipitated cerebellar proteins and confirmed by recombinant protein assays was septin-5. All 4 patients with records available had subacute onset of cerebellar ataxia with prominent eye movement symptoms (oscillopsia or vertigo). None had cancer detected. Improvements occurred after immunotherapies (2) or spontaneously (1). One patient died. Conclusion Septin-5 IgG represents a biomarker for a potentially fatal but treatable autoimmune ataxia.
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Affiliation(s)
- Josephe A Honorat
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - A Sebastian Lopez-Chiriboga
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - Thomas J Kryzer
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - James P Fryer
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - Michelle Devine
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - Angela Flores
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - Vanda A Lennon
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - Sean J Pittock
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
| | - Andrew McKeon
- Department of Laboratory Medicine and Pathology (J.A.H., T.J.K., J.P.F., V.A.L., S.J.P., A.M.), the Department of Neurology (A.S.L.-C., V.A.L., S.J.P., A.M.), and the Department of Immunology (V.A.L.), College of Medicine, Mayo Clinic, Rochester, MN; and Department of Neurology (M.D., A.F.), University of Texas, Southwestern, Dallas
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15
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Boubakar L, Falk J, Ducuing H, Thoinet K, Reynaud F, Derrington E, Castellani V. Molecular Memory of Morphologies by Septins during Neuron Generation Allows Early Polarity Inheritance. Neuron 2017; 95:834-851.e5. [DOI: 10.1016/j.neuron.2017.07.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 05/23/2017] [Accepted: 07/24/2017] [Indexed: 01/22/2023]
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