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Ruhoff VT, Leijnse N, Doostmohammadi A, Bendix PM. Filopodia: integrating cellular functions with theoretical models. Trends Cell Biol 2024:S0962-8924(24)00113-2. [PMID: 38969554 DOI: 10.1016/j.tcb.2024.05.005] [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: 02/29/2024] [Revised: 05/24/2024] [Accepted: 05/27/2024] [Indexed: 07/07/2024]
Abstract
Filopodia, widely distributed on cell surfaces, are distinguished by their dynamic extensions, playing pivotal roles in a myriad of biological processes. Their functions span from mechanosensing and guidance to cell-cell communication during cellular organization in the early embryo. Filopodia have significant roles in pathogenic processes, such as cancer invasion and viral dissemination. Molecular mapping of the filopodome has revealed generic components essential for filopodia functions. In parallel, recent insights into biophysical mechanisms governing filopodia dynamics have provided the foundation for broader investigations of filopodia's biological functions. We highlight recent discoveries of engagement of filopodia in various stages of development and pathogenesis and present an overview of intricate molecular and physical features of these cellular structures across a spectrum of cellular activities.
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Affiliation(s)
| | - Natascha Leijnse
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 København Ø, Denmark
| | - Amin Doostmohammadi
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 København Ø, Denmark
| | - Poul Martin Bendix
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 København Ø, Denmark.
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2
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Wang L, Bu T, Wu X, Li L, Sun F, Cheng CY. Motor proteins, spermatogenesis and testis function. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2024; 141:381-445. [PMID: 38960481 DOI: 10.1016/bs.apcsb.2024.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
The role of motor proteins in supporting intracellular transports of vesicles and organelles in mammalian cells has been known for decades. On the other hand, the function of motor proteins that support spermatogenesis is also well established since the deletion of motor protein genes leads to subfertility and/or infertility. Furthermore, mutations and genetic variations of motor protein genes affect fertility in men, but also a wide range of developmental defects in humans including multiple organs besides the testis. In this review, we seek to provide a summary of microtubule and actin-dependent motor proteins based on earlier and recent findings in the field. Since these two cytoskeletons are polarized structures, different motor proteins are being used to transport cargoes to different ends of these cytoskeletons. However, their involvement in germ cell transport across the blood-testis barrier (BTB) and the epithelium of the seminiferous tubules remains relatively unknown. It is based on recent findings in the field, we have provided a hypothetical model by which motor proteins are being used to support germ cell transport across the BTB and the seminiferous epithelium during the epithelial cycle of spermatogenesis. In our discussion, we have highlighted the areas of research that deserve attention to bridge the gap of research in relating the function of motor proteins to spermatogenesis.
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Affiliation(s)
- Lingling Wang
- The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, P.R. China; Department of Urology and Andrology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - Tiao Bu
- Department of Urology and Andrology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - Xiaolong Wu
- Department of Urology and Andrology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - Linxi Li
- The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, P.R. China
| | - Fei Sun
- Department of Urology and Andrology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - C Yan Cheng
- The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, P.R. China; Department of Urology and Andrology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China.
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3
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Blake TCA, Fox HM, Urbančič V, Ravishankar R, Wolowczyk A, Allgeyer ES, Mason J, Danuser G, Gallop JL. Filopodial protrusion driven by density-dependent Ena-TOCA-1 interactions. J Cell Sci 2024; 137:jcs261057. [PMID: 38323924 PMCID: PMC11006392 DOI: 10.1242/jcs.261057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 01/29/2024] [Indexed: 02/08/2024] Open
Abstract
Filopodia are narrow actin-rich protrusions with important roles in neuronal development where membrane-binding adaptor proteins, such as I-BAR- and F-BAR-domain-containing proteins, have emerged as upstream regulators that link membrane interactions to actin regulators such as formins and proteins of the Ena/VASP family. Both the adaptors and their binding partners are part of diverse and redundant protein networks that can functionally compensate for each other. To explore the significance of the F-BAR domain-containing neuronal membrane adaptor TOCA-1 (also known as FNBP1L) in filopodia we performed a quantitative analysis of TOCA-1 and filopodial dynamics in Xenopus retinal ganglion cells, where Ena/VASP proteins have a native role in filopodial extension. Increasing the density of TOCA-1 enhances Ena/VASP protein binding in vitro, and an accumulation of TOCA-1, as well as its coincidence with Ena, correlates with filopodial protrusion in vivo. Two-colour single-molecule localisation microscopy of TOCA-1 and Ena supports their nanoscale association. TOCA-1 clusters promote filopodial protrusion and this depends on a functional TOCA-1 SH3 domain and activation of Cdc42, which we perturbed using the small-molecule inhibitor CASIN. We propose that TOCA-1 clusters act independently of membrane curvature to recruit and promote Ena activity for filopodial protrusion.
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Affiliation(s)
- Thomas C. A. Blake
- Wellcome/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
| | - Helen M. Fox
- Wellcome/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
| | - Vasja Urbančič
- Wellcome/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
| | - Roshan Ravishankar
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Adam Wolowczyk
- Wellcome/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
| | - Edward S. Allgeyer
- Wellcome/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Julia Mason
- Wellcome/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
| | - Gaudenz Danuser
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jennifer L. Gallop
- Wellcome/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
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4
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Agi E, Reifenstein ET, Wit C, Schneider T, Kauer M, Kehribar M, Kulkarni A, von Kleist M, Hiesinger PR. Axonal self-sorting without target guidance in Drosophila visual map formation. Science 2024; 383:1084-1092. [PMID: 38452066 DOI: 10.1126/science.adk3043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 02/01/2024] [Indexed: 03/09/2024]
Abstract
The idea of guidance toward a target is central to axon pathfinding and brain wiring in general. In this work, we show how several thousand axonal growth cones self-pattern without target-dependent guidance during neural superposition wiring in Drosophila. Ablation of all target lamina neurons or loss of target adhesion prevents the stabilization but not the development of the pattern. Intravital imaging at the spatiotemporal resolution of growth cone dynamics in intact pupae and data-driven dynamics simulations reveal a mechanism by which >30,000 filopodia do not explore potential targets, but instead simultaneously generate and navigate a dynamic filopodial meshwork that steers growth directions. Hence, a guidance mechanism can emerge from the interactions of the axons being guided, suggesting self-organization as a more general feature of brain wiring.
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Affiliation(s)
- Egemen Agi
- Division of Neurobiology, Free University of Berlin, 14195 Berlin, Germany
| | - Eric T Reifenstein
- Department of Mathematics, Free University of Berlin, 14195 Berlin, Germany
| | - Charlotte Wit
- Division of Neurobiology, Free University of Berlin, 14195 Berlin, Germany
| | - Teresa Schneider
- Division of Neurobiology, Free University of Berlin, 14195 Berlin, Germany
| | - Monika Kauer
- Division of Neurobiology, Free University of Berlin, 14195 Berlin, Germany
| | - Melinda Kehribar
- Division of Neurobiology, Free University of Berlin, 14195 Berlin, Germany
| | - Abhishek Kulkarni
- Division of Neurobiology, Free University of Berlin, 14195 Berlin, Germany
| | - Max von Kleist
- Department of Mathematics, Free University of Berlin, 14195 Berlin, Germany
| | - P Robin Hiesinger
- Division of Neurobiology, Free University of Berlin, 14195 Berlin, Germany
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5
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Cornean J, Molina-Obando S, Gür B, Bast A, Ramos-Traslosheros G, Chojetzki J, Lörsch L, Ioannidou M, Taneja R, Schnaitmann C, Silies M. Heterogeneity of synaptic connectivity in the fly visual system. Nat Commun 2024; 15:1570. [PMID: 38383614 PMCID: PMC10882054 DOI: 10.1038/s41467-024-45971-z] [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: 12/15/2023] [Accepted: 02/08/2024] [Indexed: 02/23/2024] Open
Abstract
Visual systems are homogeneous structures, where repeating columnar units retinotopically cover the visual field. Each of these columns contain many of the same neuron types that are distinguished by anatomic, genetic and - generally - by functional properties. However, there are exceptions to this rule. In the 800 columns of the Drosophila eye, there is an anatomically and genetically identifiable cell type with variable functional properties, Tm9. Since anatomical connectivity shapes functional neuronal properties, we identified the presynaptic inputs of several hundred Tm9s across both optic lobes using the full adult female fly brain (FAFB) electron microscopic dataset and FlyWire connectome. Our work shows that Tm9 has three major and many sparsely distributed inputs. This differs from the presynaptic connectivity of other Tm neurons, which have only one major, and more stereotypic inputs than Tm9. Genetic synapse labeling showed that the heterogeneous wiring exists across individuals. Together, our data argue that the visual system uses heterogeneous, distributed circuit properties to achieve robust visual processing.
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Affiliation(s)
- Jacqueline Cornean
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Sebastian Molina-Obando
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Burak Gür
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Annika Bast
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Giordano Ramos-Traslosheros
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Jonas Chojetzki
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Lena Lörsch
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Maria Ioannidou
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Rachita Taneja
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Christopher Schnaitmann
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Marion Silies
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany.
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6
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Wolterhoff N, Hiesinger PR. Synaptic promiscuity in brain development. Curr Biol 2024; 34:R102-R116. [PMID: 38320473 PMCID: PMC10849093 DOI: 10.1016/j.cub.2023.12.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Precise synaptic connectivity is a prerequisite for the function of neural circuits, yet individual neurons, taken out of their developmental context, readily form unspecific synapses. How does the genome encode brain wiring in light of this apparent contradiction? Synaptic specificity is the outcome of a long series of developmental processes and mechanisms before, during and after synapse formation. How much promiscuity is permissible or necessary at the moment of synaptic partner choice depends on the extent to which prior development restricts available partners or subsequent development corrects initially made synapses. Synaptic promiscuity at the moment of choice can thereby play important roles in the development of precise connectivity, but also facilitate developmental flexibility and robustness. In this review, we assess the experimental evidence for the prevalence and roles of promiscuous synapse formation during brain development. Many well-established experimental approaches are based on developmental genetic perturbation and an assessment of synaptic connectivity only in the adult; this can make it difficult to pinpoint when a given defect or mechanism occurred. In many cases, such studies reveal mechanisms that restrict partner availability already prior to synapse formation. Subsequently, at the moment of choice, factors including synaptic competency, interaction dynamics and molecular recognition further restrict synaptic partners. The discussion of the development of synaptic specificity through the lens of synaptic promiscuity suggests an algorithmic process based on neurons capable of promiscuous synapse formation that are continuously prevented from making the wrong choices, with no single mechanism or developmental time point sufficient to explain the outcome.
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Affiliation(s)
- Neele Wolterhoff
- Division of Neurobiology, Free University Berlin, 14195 Berlin, Germany
| | - P Robin Hiesinger
- Division of Neurobiology, Free University Berlin, 14195 Berlin, Germany.
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7
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Ru Y, Dong S, Liu J, Liu J, Eyden B. Structural characterization and origin of surface vesicles in monocytes: another membranous pathway from cytoplasm to cell surface. Ultrastruct Pathol 2024; 48:56-65. [PMID: 38037244 DOI: 10.1080/01913123.2023.2286972] [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: 08/06/2023] [Accepted: 11/20/2023] [Indexed: 12/02/2023]
Abstract
The monocytes in acute monocytic leukemia (AML-M5b) were analyzed by scanning and transmission electron microscopy (SEM and TEM) to understand more fully their structure and origin. By SEM, monocytes exhibited localized expansions of the surface, some of which appeared to bud off as surface vesicles (SVs). Filopodial processes and pseudopodia were also present. TEM demonstrated that the SVs were composed of a double-membrane at the pole away from the cell body, and a single membrane nearer to the cell body. In the peripheral cytoplasm, intracellular vesicles (IVs) had the appearance of vacuoles and were enclosed by single membranes. Most SVs were characterized by a notch as a rER edge and an expanded head. Filopodial processes had the same thickness of 40 nm as the SV walls, which suggested a close developmental relationship between the two. Pseudopodia between SVs were irregular in size. Rod-like rER cisternae were prominent in the peripheral cytoplasm and some showed a close physical juxtaposition as to suggest a transition from rER to IVs to SVs. Ultrastructural cytochemistry demonstrated activity of 5'-nucleotidase over rER, SVs, filopodial processes and pseudopodia, and a patchy reaction over other areas of plasma membrane. Overall, the results indicated that rER transforms into SVs, filopodial processes and pseudopodia, as a way of integrating cytoplasmic membranes into the plasma membrane.
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Affiliation(s)
- Yongxin Ru
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of the Cell Ecosystem, Institute of Hematology&Blood Diseases Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Tianjin, China
- Tianjin Institutes of Health Science, Tianjin, China
| | - Shuxu Dong
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of the Cell Ecosystem, Institute of Hematology&Blood Diseases Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Tianjin, China
- Tianjin Institutes of Health Science, Tianjin, China
| | - Jing Liu
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of the Cell Ecosystem, Institute of Hematology&Blood Diseases Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Tianjin, China
- Tianjin Institutes of Health Science, Tianjin, China
| | - Jinhua Liu
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of the Cell Ecosystem, Institute of Hematology&Blood Diseases Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Tianjin, China
- Tianjin Institutes of Health Science, Tianjin, China
| | - Brian Eyden
- Department of Histopathology, Christie NHS Foundation Trust, Manchester, UK
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Gilloteaux J, De Swert K, Suain V, Nicaise C. Thalamic Neuron Resilience during Osmotic Demyelination Syndrome (ODS) Is Revealed by Primary Cilium Outgrowth and ADP-ribosylation factor-like protein 13B Labeling in Axon Initial Segment. Int J Mol Sci 2023; 24:16448. [PMID: 38003639 PMCID: PMC10671465 DOI: 10.3390/ijms242216448] [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: 10/22/2023] [Revised: 11/10/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023] Open
Abstract
A murine osmotic demyelinating syndrome (ODS) model was developed through chronic hyponatremia, induced by desmopressin subcutaneous implants, followed by precipitous sodium restoration. The thalamic ventral posterolateral (VPL) and ventral posteromedial (VPM) relay nuclei were the most demyelinated regions where neuroglial damage could be evidenced without immune response. This report showed that following chronic hyponatremia, 12 h and 48 h time lapses after rebalancing osmolarity, amid the ODS-degraded outskirts, some resilient neuronal cell bodies built up primary cilium and axon hillock regions that extended into axon initial segments (AIS) where ADP-ribosylation factor-like protein 13B (ARL13B)-immunolabeled rod-like shape content was revealed. These AIS-labeled shaft lengths appeared proportional with the distance of neuronal cell bodies away from the ODS damaged epicenter and time lapses after correction of hyponatremia. Fine structure examination verified these neuron abundant transcriptions and translation regions marked by the ARL13B labeling associated with cell neurotubules and their complex cytoskeletal macromolecular architecture. This necessitated energetic transport to organize and restore those AIS away from the damaged ODS core demyelinated zone in the murine model. These labeled structures could substantiate how thalamic neuron resilience occurred as possible steps of a healing course out of ODS.
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Affiliation(s)
- Jacques Gilloteaux
- URPhyM, NARILIS, Université de Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium; (J.G.); (K.D.S.)
- Department of Anatomical Sciences, St George’s University School of Medicine, Newcastle upon Tyne NE1 JG8, UK
| | - Kathleen De Swert
- URPhyM, NARILIS, Université de Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium; (J.G.); (K.D.S.)
| | - Valérie Suain
- Laboratoire d’Histologie Générale, Université Libre de Bruxelles, Route de Lennik 808, B-1070 Bruxelles, Belgium;
| | - Charles Nicaise
- URPhyM, NARILIS, Université de Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium; (J.G.); (K.D.S.)
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9
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Martin JR, Chatterjee A, Salecker I. Editorial: Neurobiology of Drosophila: the 19th NeuroFly-2022 meeting. Front Physiol 2023; 14:1237065. [PMID: 37398908 PMCID: PMC10311247 DOI: 10.3389/fphys.2023.1237065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 06/09/2023] [Indexed: 07/04/2023] Open
Affiliation(s)
| | - Abhishek Chatterjee
- Institut d’Écologie et des Sciences de l’Environnement de Paris (iEES-Paris), INRAE, Versailles, France
| | - Iris Salecker
- Institut de Biologie de l’École Normale Supérieure (IBENS), ENS, CNRS, INSERM, Université PSL, Paris, France
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10
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Arcuschin CD, Pinkasz M, Schor IE. Mechanisms of robustness in gene regulatory networks involved in neural development. Front Mol Neurosci 2023; 16:1114015. [PMID: 36814969 PMCID: PMC9940843 DOI: 10.3389/fnmol.2023.1114015] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 01/16/2023] [Indexed: 02/08/2023] Open
Abstract
The functions of living organisms are affected by different kinds of perturbation, both internal and external, which in many cases have functional effects and phenotypic impact. The effects of these perturbations become particularly relevant for multicellular organisms with complex body patterns and cell type heterogeneity, where transcriptional programs controlled by gene regulatory networks determine, for example, the cell fate during embryonic development. Therefore, an essential aspect of development in these organisms is the ability to maintain the functionality of their genetic developmental programs even in the presence of genetic variation, changing environmental conditions and biochemical noise, a property commonly termed robustness. We discuss the implication of different molecular mechanisms of robustness involved in neurodevelopment, which is characterized by the interplay of many developmental programs at a molecular, cellular and systemic level. We specifically focus on processes affecting the function of gene regulatory networks, encompassing transcriptional regulatory elements and post-transcriptional processes such as miRNA-based regulation, but also higher order regulatory organization, such as gene network topology. We also present cases where impairment of robustness mechanisms can be associated with neurodevelopmental disorders, as well as reasons why understanding these mechanisms should represent an important part of the study of gene regulatory networks driving neural development.
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Affiliation(s)
- Camila D. Arcuschin
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Universidad de Buenos Aires—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina,Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Marina Pinkasz
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Universidad de Buenos Aires—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Ignacio E. Schor
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Universidad de Buenos Aires—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina,Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina,*Correspondence: Ignacio E. Schor ✉
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11
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Radler MR, Liu X, Peng M, Doyle B, Toyo-Oka K, Spiliotis ET. Pyramidal neuron morphogenesis requires a septin network that stabilizes filopodia and suppresses lamellipodia during neurite initiation. Curr Biol 2023; 33:434-448.e8. [PMID: 36538929 PMCID: PMC9905282 DOI: 10.1016/j.cub.2022.11.043] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 10/31/2022] [Accepted: 11/18/2022] [Indexed: 12/23/2022]
Abstract
Pyramidal neurons are a major cell type of the forebrain, consisting of a pyramidally shaped soma with axonal and apicobasal dendritic processes. It is poorly understood how the neuronal soma develops its pyramidal morphology, while generating neurites of the proper shape and orientation. Here, we discovered that the spherical somata of immature neurite-less neurons possess a circumferential wreath-like network of septin filaments, which promotes neuritogenesis by balancing the protrusive activity of lamellipodia and filopodia. In embryonic rat hippocampal and mouse cortical neurons, the septin wreath network consists of curvilinear filaments that contain septins 5, 7, and 11 (Sept5/7/11). The Sept5/7/11 wreath network demarcates a zone of myosin II enrichment and Arp2/3 diminution at the base of filopodial actin bundles. In Sept7-depleted neurons, cell bodies are enlarged with hyperextended lamellae and abnormally shaped neurites that originate from lamellipodia. This phenotype is accompanied by diminished myosin II and filopodia lifetimes and increased Arp2/3 and lamellipodial activity. Inhibition of Arp2/3 rescues soma and neurite phenotypes, indicating that the septin wreath network suppresses the extension of lamellipodia, facilitating the formation of neurites from the filopodia of a consolidated soma. We show that this septin function is critical for developing a pyramidally shaped soma with properly distributed and oriented dendrites in cultured rat hippocampal neurons and in vivo in mouse perinatal cortical neurons. Therefore, the somatic septin cytoskeleton provides a key morphogenetic mechanism for neuritogenesis and the development of pyramidal neurons.
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Affiliation(s)
- Megan R Radler
- Department of Biology, Drexel University, 3245 Chestnut Street, Philadelphia, PA 19104, USA
| | - Xiaonan Liu
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, USA
| | - Megan Peng
- Department of Biology, Drexel University, 3245 Chestnut Street, Philadelphia, PA 19104, USA
| | - Brenna Doyle
- Department of Biology, Drexel University, 3245 Chestnut Street, Philadelphia, PA 19104, USA
| | - Kazuhito Toyo-Oka
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, USA
| | - Elias T Spiliotis
- Department of Biology, Drexel University, 3245 Chestnut Street, Philadelphia, PA 19104, USA.
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12
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Extracellular Vesicles and Membrane Protrusions in Developmental Signaling. J Dev Biol 2022; 10:jdb10040039. [PMID: 36278544 PMCID: PMC9589955 DOI: 10.3390/jdb10040039] [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: 08/10/2022] [Revised: 09/13/2022] [Accepted: 09/16/2022] [Indexed: 02/08/2023] Open
Abstract
During embryonic development, cells communicate with each other to determine cell fate, guide migration, and shape morphogenesis. While the relevant secreted factors and their downstream target genes have been characterized extensively, how these signals travel between embryonic cells is still emerging. Evidence is accumulating that extracellular vesicles (EVs), which are well defined in cell culture and cancer, offer a crucial means of communication in embryos. Moreover, the release and/or reception of EVs is often facilitated by fine cellular protrusions, which have a history of study in development. However, due in part to the complexities of identifying fragile nanometer-scale extracellular structures within the three-dimensional embryonic environment, the nomenclature of developmental EVs and protrusions can be ambiguous, confounding progress. In this review, we provide a robust guide to categorizing these structures in order to enable comparisons between developmental systems and stages. Then, we discuss existing evidence supporting a role for EVs and fine cellular protrusions throughout development.
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Fuchs J, Bareesel S, Kroon C, Polyzou A, Eickholt BJ, Leondaritis G. Plasma membrane phospholipid phosphatase-related proteins as pleiotropic regulators of neuron growth and excitability. Front Mol Neurosci 2022; 15:984655. [PMID: 36187351 PMCID: PMC9520309 DOI: 10.3389/fnmol.2022.984655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 08/23/2022] [Indexed: 11/22/2022] Open
Abstract
Neuronal plasma membrane proteins are essential for integrating cell extrinsic and cell intrinsic signals to orchestrate neuronal differentiation, growth and plasticity in the developing and adult nervous system. Here, we shed light on the family of plasma membrane proteins phospholipid phosphatase-related proteins (PLPPRs) (alternative name, PRGs; plasticity-related genes) that fine-tune neuronal growth and synaptic transmission in the central nervous system. Several studies uncovered essential functions of PLPPRs in filopodia formation, axon guidance and branching during nervous system development and regeneration, as well as in the control of dendritic spine number and excitability. Loss of PLPPR expression in knockout mice increases susceptibility to seizures, and results in defects in sensory information processing, development of psychiatric disorders, stress-related behaviors and abnormal social interaction. However, the exact function of PLPPRs in the context of neurological diseases is largely unclear. Although initially described as active lysophosphatidic acid (LPA) ecto-phosphatases that regulate the levels of this extracellular bioactive lipid, PLPPRs lack catalytic activity against LPA. Nevertheless, they emerge as atypical LPA modulators, by regulating LPA mediated signaling processes. In this review, we summarize the effects of this protein family on cellular morphology, generation and maintenance of cellular protrusions as well as highlight their known neuronal functions and phenotypes of KO mice. We discuss the molecular mechanisms of PLPPRs including the deployment of phospholipids, actin-cytoskeleton and small GTPase signaling pathways, with a focus on identifying gaps in our knowledge to stimulate interest in this understudied protein family.
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Affiliation(s)
- Joachim Fuchs
- Institute of Molecular Biology and Biochemistry, Charité – Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Shannon Bareesel
- Institute of Molecular Biology and Biochemistry, Charité – Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Cristina Kroon
- Institute of Molecular Biology and Biochemistry, Charité – Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Alexandra Polyzou
- Department of Pharmacology, Faculty of Medicine, School of Health Sciences, University of Ioannina, Ioannina, Greece
| | - Britta J. Eickholt
- Institute of Molecular Biology and Biochemistry, Charité – Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
- *Correspondence: Britta J. Eickholt,
| | - George Leondaritis
- Department of Pharmacology, Faculty of Medicine, School of Health Sciences, University of Ioannina, Ioannina, Greece
- Institute of Biosciences, University Research Center Ioannina, University of Ioannina, Ioannina, Greece
- George Leondaritis,
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