1
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Kim N, Li Y, Yu R, Kwon HS, Song A, Jun MH, Jeong JY, Lee JH, Lim HH, Kim MJ, Kim JW, Oh WJ. Repulsive Sema3E-Plexin-D1 signaling coordinates both axonal extension and steering via activating an autoregulatory factor, Mtss1. eLife 2024; 13:e96891. [PMID: 38526535 PMCID: PMC11001299 DOI: 10.7554/elife.96891] [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: 02/07/2024] [Accepted: 03/14/2024] [Indexed: 03/26/2024] Open
Abstract
Axon guidance molecules are critical for neuronal pathfinding because they regulate directionality and growth pace during nervous system development. However, the molecular mechanisms coordinating proper axonal extension and turning are poorly understood. Here, metastasis suppressor 1 (Mtss1), a membrane protrusion protein, ensured axonal extension while sensitizing axons to the Semaphorin 3E (Sema3E)-Plexin-D1 repulsive cue. Sema3E-Plexin-D1 signaling enhanced Mtss1 expression in projecting striatonigral neurons. Mtss1 localized to the neurite axonal side and regulated neurite outgrowth in cultured neurons. Mtss1 also aided Plexin-D1 trafficking to the growth cone, where it signaled a repulsive cue to Sema3E. Mtss1 ablation reduced neurite extension and growth cone collapse in cultured neurons. Mtss1-knockout mice exhibited fewer striatonigral projections and irregular axonal routes, and these defects were recapitulated in Plxnd1- or Sema3e-knockout mice. These findings demonstrate that repulsive axon guidance activates an exquisite autoregulatory program coordinating both axonal extension and steering during neuronal pathfinding.
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Affiliation(s)
- Namsuk Kim
- Neurovascular Unit Research Group, Korea Brain Research InstituteDaeguRepublic of Korea
| | - Yan Li
- Neurovascular Unit Research Group, Korea Brain Research InstituteDaeguRepublic of Korea
| | - Ri Yu
- Neurovascular Unit Research Group, Korea Brain Research InstituteDaeguRepublic of Korea
| | - Hyo-Shin Kwon
- Neurovascular Unit Research Group, Korea Brain Research InstituteDaeguRepublic of Korea
| | - Anji Song
- Neurovascular Unit Research Group, Korea Brain Research InstituteDaeguRepublic of Korea
| | - Mi-Hee Jun
- Neurovascular Unit Research Group, Korea Brain Research InstituteDaeguRepublic of Korea
| | - Jin-Young Jeong
- Neurovascular Unit Research Group, Korea Brain Research InstituteDaeguRepublic of Korea
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and TechnologyDaeguRepublic of Korea
| | - Ji Hyun Lee
- Neurovascular Unit Research Group, Korea Brain Research InstituteDaeguRepublic of Korea
| | - Hyun-Ho Lim
- Neurovascular Unit Research Group, Korea Brain Research InstituteDaeguRepublic of Korea
| | - Mi-Jin Kim
- Department of Life Sciences, Chung-Ang UniversitySeoulRepublic of Korea
| | - Jung-Woong Kim
- Department of Life Sciences, Chung-Ang UniversitySeoulRepublic of Korea
| | - Won-Jong Oh
- Neurovascular Unit Research Group, Korea Brain Research InstituteDaeguRepublic of Korea
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2
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Khazma T, Golan-Vaishenker Y, Guez-Haddad J, Grossman A, Sain R, Weitman M, Plotnikov A, Zalk R, Yaron A, Hons M, Opatowsky Y. A duplex structure of SARM1 octamers stabilized by a new inhibitor. Cell Mol Life Sci 2022; 80:16. [PMID: 36564647 PMCID: PMC11072711 DOI: 10.1007/s00018-022-04641-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 11/16/2022] [Accepted: 11/19/2022] [Indexed: 12/25/2022]
Abstract
In recent years, there has been growing interest in SARM1 as a potential breakthrough drug target for treating various pathologies of axon degeneration. SARM1-mediated axon degeneration relies on its TIR domain NADase activity, but recent structural data suggest that the non-catalytic ARM domain could also serve as a pharmacological site as it has an allosteric inhibitory function. Here, we screened for synthetic small molecules that inhibit SARM1, and tested a selected set of these compounds in a DRG axon degeneration assay. Using cryo-EM, we found that one of the newly discovered inhibitors, a calmidazolium designated TK106, not only stabilizes the previously reported inhibited conformation of the octamer, but also a meta-stable structure: a duplex of octamers (16 protomers), which we have now determined to 4.0 Å resolution. In the duplex, each ARM domain protomer is engaged in lateral interactions with neighboring protomers, and is further stabilized by contralateral contacts with the opposing octamer ring. Mutagenesis of the duplex contact sites leads to a moderate increase in SARM1 activation in cultured cells. Based on our data we propose that the duplex assembly constitutes an additional auto-inhibition mechanism that tightly prevents pre-mature activation and axon degeneration.
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Affiliation(s)
- Tami Khazma
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | | | - Julia Guez-Haddad
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Atira Grossman
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Radhika Sain
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Michal Weitman
- Department of Chemistry, Bar-Ilan University, Ramat Gan, Israel
| | - Alexander Plotnikov
- The Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot, Israel
| | - Ran Zalk
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
- Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Avraham Yaron
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Michael Hons
- European Molecular Biology Laboratory, Grenoble, France.
| | - Yarden Opatowsky
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
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3
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Serre JM, Lucas B, Martin SCT, Heier JA, Shao X, Hardin J. C. elegans srGAP is an α-catenin M domain-binding protein that strengthens cadherin-dependent adhesion during morphogenesis. Development 2022; 149:dev200775. [PMID: 36125129 PMCID: PMC10655919 DOI: 10.1242/dev.200775] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 08/23/2022] [Indexed: 11/20/2022]
Abstract
The cadherin-catenin complex (CCC) is central to embryonic development and tissue repair, yet how CCC binding partners function alongside core CCC components remains poorly understood. Here, we establish a previously unappreciated role for an evolutionarily conserved protein, the slit-robo GTPase-activating protein SRGP-1/srGAP, in cadherin-dependent morphogenetic processes in the Caenorhabditis elegans embryo. SRGP-1 binds to the M domain of the core CCC component, HMP-1/α-catenin, via its C terminus. The SRGP-1 C terminus is sufficient to target it to adherens junctions, but only during later embryonic morphogenesis, when junctional tension is known to increase. Surprisingly, mutations that disrupt stabilizing salt bridges in the M domain block this recruitment. Loss of SRGP-1 leads to an increase in mobility and decrease of junctional HMP-1. In sensitized genetic backgrounds with weakened adherens junctions, loss of SRGP-1 leads to late embryonic failure. Rescue of these phenotypes requires the C terminus of SRGP-1 but also other domains of the protein. Taken together, these data establish a role for an srGAP in stabilizing and organizing the CCC during epithelial morphogenesis by binding to a partially closed conformation of α-catenin at junctions.
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Affiliation(s)
- Joel M. Serre
- Program in Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Bethany Lucas
- Department of Biology, Regis University, 3333 Regis Blvd., Denver, CO 80221, USA
| | - Sterling C. T. Martin
- Biophysics Graduate Program, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jonathon A. Heier
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Xiangqiang Shao
- Wisconsin State Laboratory of Hygiene, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jeff Hardin
- Program in Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
- Biophysics Graduate Program, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
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4
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Dionne U, Percival LJ, Chartier FJM, Landry CR, Bisson N. SRC homology 3 domains: multifaceted binding modules. Trends Biochem Sci 2022; 47:772-784. [PMID: 35562294 DOI: 10.1016/j.tibs.2022.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/30/2022] [Accepted: 04/11/2022] [Indexed: 12/15/2022]
Abstract
The assembly of complexes following the detection of extracellular signals is often controlled by signaling proteins comprising multiple peptide binding modules. The SRC homology (SH)3 family represents the archetypical modular protein interaction module, with ~300 annotated SH3 domains in humans that regulate an impressive array of signaling processes. We review recent findings regarding the allosteric contributions of SH3 domains host protein context, their phosphoregulation, and their roles in phase separation that challenge the simple model in which SH3s are considered to be portable domains binding to specific proline-rich peptide motifs.
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Affiliation(s)
- Ugo Dionne
- Centre de recherche sur le cancer et Centre de recherche du CHU de Québec - Université Laval, QC, Canada; Quebec Network for Research on Protein Function, Engineering, and Applications (PROTEO), QC, Canada
| | - Lily J Percival
- Centre de recherche sur le cancer et Centre de recherche du CHU de Québec - Université Laval, QC, Canada; Quebec Network for Research on Protein Function, Engineering, and Applications (PROTEO), QC, Canada; School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, The Michael Smith Building, Manchester, UK
| | - François J M Chartier
- Centre de recherche sur le cancer et Centre de recherche du CHU de Québec - Université Laval, QC, Canada; Quebec Network for Research on Protein Function, Engineering, and Applications (PROTEO), QC, Canada
| | - Christian R Landry
- Quebec Network for Research on Protein Function, Engineering, and Applications (PROTEO), QC, Canada; Institute of Integrative and Systems Biology, Université Laval, Quebec, QC, Canada; Department of Biochemistry, Microbiology and Bioinformatics, Université Laval, Quebec, QC, Canada; Department of Biology, Université Laval, Quebec, QC, Canada.
| | - Nicolas Bisson
- Centre de recherche sur le cancer et Centre de recherche du CHU de Québec - Université Laval, QC, Canada; Quebec Network for Research on Protein Function, Engineering, and Applications (PROTEO), QC, Canada; Department of Molecular Biology, Medical Biochemistry and Pathology, Université Laval, Quebec, QC, Canada.
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5
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Ho NTT, Rahane CS, Pramanik S, Kim PS, Kutzner A, Heese K. FAM72, Glioblastoma Multiforme (GBM) and Beyond. Cancers (Basel) 2021; 13:cancers13051025. [PMID: 33804473 PMCID: PMC7957592 DOI: 10.3390/cancers13051025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/18/2021] [Accepted: 02/22/2021] [Indexed: 12/15/2022] Open
Abstract
Simple Summary Glioblastoma multiforme (GBM) is a serious and aggressive cancer disease that has not allowed scientists to rest for decades. In this review, we consider the new gene pair |-SRGAP2–FAM72-| and discuss its role in the cell cycle and the possibility of defining new therapeutic approaches for the treatment of GBM and other cancers via this gene pair |-SRGAP2–FAM72-|. Abstract Neural stem cells (NSCs) offer great potential for regenerative medicine due to their excellent ability to differentiate into various specialized cell types of the brain. In the central nervous system (CNS), NSC renewal and differentiation are under strict control by the regulation of the pivotal SLIT-ROBO Rho GTPase activating protein 2 (SRGAP2)—Family with sequence similarity 72 (FAM72) master gene (i.e., |-SRGAP2–FAM72-|) via a divergent gene transcription activation mechanism. If the gene transcription control unit (i.e., the intergenic region of the two sub-gene units, SRGAP2 and FAM72) gets out of control, NSCs may transform into cancer stem cells and generate brain tumor cells responsible for brain cancer such as glioblastoma multiforme (GBM). Here, we discuss the surveillance of this |-SRGAP2–FAM72-| master gene and its role in GBM, and also in light of FAM72 for diagnosing various types of cancers outside of the CNS.
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Affiliation(s)
- Nguyen Thi Thanh Ho
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Korea;
| | - Chinmay Satish Rahane
- Maharashtra Institute of Medical Education and Research, Talegaon Dabhade, Maharashtra 410507, India;
| | - Subrata Pramanik
- Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany;
| | - Pok-Son Kim
- Department of Mathematics, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702, Korea;
| | - Arne Kutzner
- Department of Information Systems, College of Computer Science, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Korea;
| | - Klaus Heese
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Korea;
- Correspondence:
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6
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The human-specific paralogs SRGAP2B and SRGAP2C differentially modulate SRGAP2A-dependent synaptic development. Sci Rep 2019; 9:18692. [PMID: 31822692 PMCID: PMC6904453 DOI: 10.1038/s41598-019-54887-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 11/20/2019] [Indexed: 02/06/2023] Open
Abstract
Human-specific gene duplications (HSGDs) have recently emerged as key modifiers of brain development and evolution. However, the molecular mechanisms underlying the function of HSGDs remain often poorly understood. In humans, a truncated duplication of SRGAP2A led to the emergence of two human-specific paralogs: SRGAP2B and SRGAP2C. The ancestral copy SRGAP2A limits synaptic density and promotes maturation of both excitatory (E) and inhibitory (I) synapses received by cortical pyramidal neurons (PNs). SRGAP2C binds to and inhibits all known functions of SRGAP2A leading to an increase in E and I synapse density and protracted synapse maturation, traits characterizing human cortical neurons. Here, we demonstrate how the evolutionary changes that led to the emergence of SRGAP2 HSGDs generated proteins that, in neurons, are intrinsically unstable and, upon hetero-dimerization with SRGAP2A, reduce SRGAP2A levels in a proteasome-dependent manner. Moreover, we show that, despite only a few non-synonymous mutations specifically targeting arginine residues, SRGAP2C is unique compared to SRGAP2B in its ability to induce long-lasting changes in synaptic density throughout adulthood. These mutations led to the ability of SRGAP2C to inhibit SRGAP2A function and thereby contribute to the emergence of human-specific features of synaptic development during evolution.
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7
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Sporny M, Guez-Haddad J, Lebendiker M, Ulisse V, Volf A, Mim C, Isupov MN, Opatowsky Y. Structural Evidence for an Octameric Ring Arrangement of SARM1. J Mol Biol 2019; 431:3591-3605. [PMID: 31278906 DOI: 10.1016/j.jmb.2019.06.030] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/16/2019] [Accepted: 06/25/2019] [Indexed: 12/11/2022]
Abstract
SARM1 induces axonal degeneration in response to various insults and is therefore considered an attractive drug target for the treatment of neuro-degenerative diseases as well as for brain and spinal cord injuries. SARM1 activity depends on the integrity of the protein's SAM domains, as well as on the enzymatic conversion of NAD+ to ADPR (ADP Ribose) products by the SARM1's TIR domain. Therefore, inhibition of either SAM or TIR functions may constitute an effective therapeutic strategy. However, there is currently no SARM1-directed therapeutic approach available because of an insufficient structural and mechanistic understanding of this protein. In this study, we found that SARM1 assembles into an octameric ring. This arrangement was not described before in other SAM proteins, but is reminiscent of the apoptosome and inflammasome-well-known apoptotic ring-like oligomers. We show that both SARM1 and the isolated tandem SAM1-2 domains form octamers in solution, and electron microscopy analysis reveals an octameric ring of SARM1. We determined the crystal structure of SAM1-2 and found that it also forms a closed octameric ring in the crystal lattice. The SAM1-2 ring interactions are mediated by complementing "lock and key" hydrophobic grooves and inserts and electrostatic charges between the neighboring protomers. We have mutated several interacting SAM1-2 interfaces and measured how these mutations affect SARM1 apoptotic activity in cultured cells, and in this way identified critical oligomerization sites that facilitate cell death. These results highlight the importance of oligomerization for SARM1 function and reveal critical epitopes for future targeted drug development.
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Affiliation(s)
- Michael Sporny
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Julia Guez-Haddad
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Mario Lebendiker
- Wolfson Centre for Applied Structural Biology, The Hebrew University of Jerusalem, Israel
| | - Valeria Ulisse
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Allison Volf
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Carsten Mim
- Department of Biomedical Engineering and Health Solutions, Royal Technical Institute (KTH), Stockholm, Sweden; Department of Nutrition and Biosciences, Karolinska Institute, Huddinge, Sweden
| | | | - Yarden Opatowsky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel.
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8
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Xu Z, Chen Y, Chen Y. Spatiotemporal Regulation of Rho GTPases in Neuronal Migration. Cells 2019; 8:cells8060568. [PMID: 31185627 PMCID: PMC6627650 DOI: 10.3390/cells8060568] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 06/01/2019] [Accepted: 06/04/2019] [Indexed: 12/17/2022] Open
Abstract
Neuronal migration is essential for the orchestration of brain development and involves several contiguous steps: interkinetic nuclear movement (INM), multipolar–bipolar transition, locomotion, and translocation. Growing evidence suggests that Rho GTPases, including RhoA, Rac, Cdc42, and the atypical Rnd members, play critical roles in neuronal migration by regulating both actin and microtubule cytoskeletal components. This review focuses on the spatiotemporal-specific regulation of Rho GTPases as well as their regulators and effectors in distinct steps during the neuronal migration process. Their roles in bridging extracellular signals and cytoskeletal dynamics to provide optimal structural support to the migrating neurons will also be discussed.
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Affiliation(s)
- Zhenyan Xu
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, Guangdong, China.
| | - Yuewen Chen
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, Guangdong, China.
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, HKUST Shenzhen Research Institute, Shenzhen 518057, Guangdong, China.
| | - Yu Chen
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, Guangdong, China.
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, HKUST Shenzhen Research Institute, Shenzhen 518057, Guangdong, China.
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9
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Taylor KL, Taylor RJ, Richters KE, Huynh B, Carrington J, McDermott ME, Wilson RL, Dent EW. Opposing functions of F-BAR proteins in neuronal membrane protrusion, tubule formation, and neurite outgrowth. Life Sci Alliance 2019; 2:2/3/e201800288. [PMID: 31160379 PMCID: PMC6549137 DOI: 10.26508/lsa.201800288] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 05/15/2019] [Accepted: 05/17/2019] [Indexed: 01/08/2023] Open
Abstract
Neurite formation is a fundamental antecedent to axon and dendrite formation, but the mechanisms that underlie this important process are poorly characterized. Here, we demonstrate that two F-BAR proteins, CIP4 and FBP17, have opposing functions in early cortical neuron development. The F-BAR family of proteins play important roles in many cellular processes by regulating both membrane and actin dynamics. The CIP4 family of F-BAR proteins is widely recognized to function in endocytosis by elongating endocytosing vesicles. However, in primary cortical neurons, CIP4 concentrates at the tips of extending lamellipodia and filopodia and inhibits neurite outgrowth. Here, we report that the highly homologous CIP4 family member, FBP17, induces tubular structures in primary cortical neurons and results in precocious neurite formation. Through domain swapping and deletion experiments, we demonstrate that a novel polybasic region between the F-BAR and HR1 domains is required for membrane bending. Moreover, the presence of a poly-PxxP region in longer splice isoforms of CIP4 and FBP17 largely reverses the localization and function of these proteins. Thus, CIP4 and FBP17 function as an antagonistic pair to fine-tune membrane protrusion, endocytosis, and neurite formation during early neuronal development.
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Affiliation(s)
- Kendra L Taylor
- University of Wisconsin-Madison, Neuroscience Training Program, Madison, WI, USA
| | - Russell J Taylor
- University of Wisconsin-Madison, Neuroscience Training Program, Madison, WI, USA
| | - Karl E Richters
- University of Wisconsin-Madison, Department of Neuroscience, Madison, WI, USA
| | - Brandon Huynh
- University of Wisconsin-Madison, Department of Neuroscience, Madison, WI, USA
| | - Justin Carrington
- University of Wisconsin-Madison, Department of Neuroscience, Madison, WI, USA
| | - Maeve E McDermott
- University of Wisconsin-Madison, Department of Neuroscience, Madison, WI, USA
| | - Rebecca L Wilson
- University of Wisconsin-Madison, Department of Neuroscience, Madison, WI, USA
| | - Erik W Dent
- University of Wisconsin-Madison, Department of Neuroscience, Madison, WI, USA
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10
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Abstract
The creation of complex neuronal networks relies on ligand-receptor interactions that mediate attraction or repulsion towards specific targets. Roundabouts comprise a family of single-pass transmembrane receptors facilitating this process upon interaction with the soluble extracellular ligand Slit protein family emanating from the midline. Due to the complexity and flexible nature of Robo receptors , their overall structure has remained elusive until now. Recent structural studies of the Robo 1 and Robo 2 ectodomains have provided the basis for a better understanding of their signalling mechanism. These structures reveal how Robo receptors adopt an auto-inhibited conformation on the cell surface that can be further stabilised by cis and/or trans oligmerisation arrays. Upon Slit -N binding Robo receptors must undergo a conformational change for Ig4 mediated dimerisation and signaling, probably via endocytosis. Furthermore, it's become clear that Robo receptors do not only act alone, but as large and more complex cell surface receptor assemblies to manifest directional and growth effects in a concerted fashion. These context dependent assemblies provide a mechanism to fine tune attractive and repulsive signals in a combinatorial manner required during neuronal development. While a mechanistic understanding of Slit mediated Robo signaling has advanced significantly further structural studies on larger assemblies are required for the design of new experiments to elucidate their role in cell surface receptor complexes. These will be necessary to understand the role of Slit -Robo signaling in neurogenesis, angiogenesis, organ development and cancer progression. In this chapter, we provide a review of the current knowledge in the field with a particular focus on the Roundabout receptor family.
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Affiliation(s)
- Francesco Bisiak
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue Des Martyrs, 38042, Grenoble, France.
| | - Andrew A McCarthy
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue Des Martyrs, 38042, Grenoble, France.
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11
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Pan Y, Jiang S, Hou Q, Qiu D, Shi J, Wang L, Chen Z, Zhang M, Duan A, Qin W, Zen K, Liu Z. Dissection of Glomerular Transcriptional Profile in Patients With Diabetic Nephropathy: SRGAP2a Protects Podocyte Structure and Function. Diabetes 2018; 67:717-730. [PMID: 29242313 DOI: 10.2337/db17-0755] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 10/26/2017] [Indexed: 01/19/2023]
Abstract
Podocytes play a pivotal role in maintaining glomerular filtration function through their interdigitated foot processes. However, the mechanisms that govern the podocyte cytoskeletal rearrangement remain unclear. Through analyzing the transcriptional profile of renal biopsy specimens from patients with diabetic nephropathy (DN) and control donors, we identify SLIT-ROBO ρGTPase-activating protein 2a (SRGAP2a) as one of the main hub genes strongly associated with proteinuria and glomerular filtration in type 2 DN. Immunofluorescence staining and Western blot analysis revealed that human and mouse SRGAP2a is primarily localized at podocytes and largely colocalized with synaptopodin. Moreover, podocyte SRGAP2a is downregulated in patients with DN and db/db mice at both the mRNA and the protein level. SRGAP2a reduction is observed in cultured podocytes treated with tumor growth factor-β or high concentrations of glucose. Functional and mechanistic studies show that SRGAP2a suppresses podocyte motility through inactivating RhoA/Cdc42 but not Rac1. The protective role of SRGAP2a in podocyte function also is confirmed in zebrafish, in which knockdown of SRGAP2a, a SRGAP2 ortholog in zebrafish, recapitulates podocyte foot process effacement. Finally, increasing podocyte SRGAP2a levels in db/db mice through administration of adenovirus-expressing SRGAP2a significantly mitigates podocyte injury and proteinuria. The results demonstrate that SRGAP2a protects podocytes by suppressing podocyte migration.
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Affiliation(s)
- Yu Pan
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Song Jiang
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Qing Hou
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Dandan Qiu
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Jingsong Shi
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Ling Wang
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Zhaohong Chen
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Mingchao Zhang
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Aiping Duan
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Weisong Qin
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Ke Zen
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Zhihong Liu
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
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12
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Abstract
The Slit-Robo GTPase-activating proteins (srGAPs) were first identified as potential Slit-Robo effectors that influence growth cone guidance. Given their N-terminal F-BAR, central GAP and C-terminal SH3 domains, srGAPs have the potential to affect membrane dynamics, Rho family GTPase activity and other binding partners. Recent research has clarified how srGAP family members act in distinct ways at the cell membrane, and has expanded our understanding of the roles of srGAPs in neuronal and non-neuronal cells. Gene duplication of the human-specific paralog of srGAP2 has resulted in srGAP2 family proteins that may have increased the density of dendritic spines and promoted neoteny of the human brain during crucial periods of human evolution, underscoring the importance of srGAPs in the unique sculpting of the human brain. Importantly, srGAPs also play roles outside of the nervous system, including during contact inhibition of cell movement and in establishing and maintaining cell adhesions in epithelia. Changes in srGAP expression may contribute to neurodevelopmental disorders, cancer metastasis and inflammation. As discussed in this Review, much remains to be discovered about how this interesting family of proteins functions in a diverse set of processes in metazoans and the functional roles srGAPs play in human disease.
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Affiliation(s)
- Bethany Lucas
- Program in Genetics, University of Wisconsin-Madison, 1117 W. Johnson St., Madison, WI 53706, USA
| | - Jeff Hardin
- Program in Genetics, University of Wisconsin-Madison, 1117 W. Johnson St., Madison, WI 53706, USA
- Department of Integrative Biology, University of Wisconsin-Madison, 1117 W. Johnson St., Madison, WI 53706, USA
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13
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Sporny M, Guez-Haddad J, Kreusch A, Shakartzi S, Neznansky A, Cross A, Isupov MN, Qualmann B, Kessels MM, Opatowsky Y. Structural History of Human SRGAP2 Proteins. Mol Biol Evol 2017; 34:1463-1478. [PMID: 28333212 PMCID: PMC5435084 DOI: 10.1093/molbev/msx094] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In the development of the human brain, human-specific genes are considered to play key roles, conferring its unique advantages and vulnerabilities. At the time of Homo lineage divergence from Australopithecus, SRGAP2C gradually emerged through a process of serial duplications and mutagenesis from ancestral SRGAP2A (3.4–2.4 Ma). Remarkably, ectopic expression of SRGAP2C endows cultured mouse brain cells, with human-like characteristics, specifically, increased dendritic spine length and density. To understand the molecular mechanisms underlying this change in neuronal morphology, we determined the structure of SRGAP2A and studied the interplay between SRGAP2A and SRGAP2C. We found that: 1) SRGAP2A homo-dimerizes through a large interface that includes an F-BAR domain, a newly identified F-BAR extension (Fx), and RhoGAP-SH3 domains. 2) SRGAP2A has an unusual inverse geometry, enabling associations with lamellipodia and dendritic spine heads in vivo, and scaffolding of membrane protrusions in cell culture. 3) As a result of the initial partial duplication event (∼3.4 Ma), SRGAP2C carries a defective Fx-domain that severely compromises its solubility and membrane-scaffolding ability. Consistently, SRGAP2A:SRAGP2C hetero-dimers form, but are insoluble, inhibiting SRGAP2A activity. 4) Inactivation of SRGAP2A is sensitive to the level of hetero-dimerization with SRGAP2C. 5) The primal form of SRGAP2C (P-SRGAP2C, existing between ∼3.4 and 2.4 Ma) is less effective in hetero-dimerizing with SRGAP2A than the modern SRGAP2C, which carries several substitutions (from ∼2.4 Ma). Thus, the genetic mutagenesis phase contributed to modulation of SRGAP2A’s inhibition of neuronal expansion, by introducing and improving the formation of inactive SRGAP2A:SRGAP2C hetero-dimers, indicating a stepwise involvement of SRGAP2C in human evolutionary history.
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Affiliation(s)
- Michael Sporny
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Julia Guez-Haddad
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Annett Kreusch
- Institute for Biochemistry I, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Sivan Shakartzi
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Avi Neznansky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Alice Cross
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Michail N Isupov
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Britta Qualmann
- Institute for Biochemistry I, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Michael M Kessels
- Institute for Biochemistry I, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Yarden Opatowsky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
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14
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Huang GH, Sun ZL, Li HJ, Feng DF. Rho GTPase-activating proteins: Regulators of Rho GTPase activity in neuronal development and CNS diseases. Mol Cell Neurosci 2017; 80:18-31. [PMID: 28163190 DOI: 10.1016/j.mcn.2017.01.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 01/06/2017] [Accepted: 01/29/2017] [Indexed: 12/22/2022] Open
Abstract
The Rho family of small GTPases was considered as molecular switches in regulating multiple cellular events, including cytoskeleton reorganization. The Rho GTPase-activating proteins (RhoGAPs) are one of the major families of Rho GTPase regulators. RhoGAPs were initially considered negative mediators of Rho signaling pathways via their GAP domain. Recent studies have demonstrated that RhoGAPs also regulate numerous aspects of neuronal development and are related to various neurodegenerative diseases in GAP-dependent and GAP-independent manners. Moreover, RhoGAPs are regulated through various mechanisms, such as phosphorylation. To date, approximately 70 RhoGAPs have been identified; however, only a small portion has been thoroughly investigated. Thus, the characterization of important RhoGAPs in the central nervous system is crucial to understand their spatiotemporal role during different stages of neuronal development. In this review, we summarize the current knowledge of RhoGAPs in the brain with an emphasis on their molecular function, regulation mechanism and disease implications in the central nervous system.
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Affiliation(s)
- Guo-Hui Huang
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Zhao-Liang Sun
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Hong-Jiang Li
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Dong-Fu Feng
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China; Institute of Traumatic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China.
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15
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Sporny M, Guez-Haddad J, Waterman DG, Isupov MN, Opatowsky Y. Molecular symmetry-constrained systematic search approach to structure solution of the coiled-coil SRGAP2 F-BARx domain. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2016; 72:1241-1253. [PMID: 27917825 DOI: 10.1107/s2059798316016697] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 10/18/2016] [Indexed: 02/05/2023]
Abstract
SRGAP2 (Slit-Robo GTPase-activating protein 2) is a cytoplasmic protein found to be involved in neuronal branching, restriction of neuronal migration and restriction of the length and density of dendritic postsynaptic spines. The extended F-BAR (F-BARx) domain of SRGAP2 generates membrane protrusions when expressed in COS-7 cells, while most F-BARs induce the opposite effect: membrane invaginations. As a first step to understand this discrepancy, the F-BARx domain of SRGAP2 was isolated and crystallized after co-expression with the carboxy domains of the protein. Diffraction data were collected from two significantly non-isomorphous crystals in the same monoclinic C2 space group. A correct molecular-replacment solution was obtained by applying a molecular symmetry-constrained systematic search approach that took advantage of the conserved biological symmetry of the F-BAR domains. It is shown that similar approaches can solve other F-BAR structures that were previously determined by experimental phasing. Diffraction data were reprocessed with a high-resolution cutoff of 2.2 Å, chosen using less strict statistical criteria. This has improved the outcome of multi-crystal averaging and other density-modification procedures.
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Affiliation(s)
- Michael Sporny
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Julia Guez-Haddad
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | | | | | - Yarden Opatowsky
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
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Coordinated autoinhibition of F-BAR domain membrane binding and WASp activation by Nervous Wreck. Proc Natl Acad Sci U S A 2016; 113:E5552-61. [PMID: 27601635 DOI: 10.1073/pnas.1524412113] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Membrane remodeling by Fes/Cip4 homology-Bin/Amphiphysin/Rvs167 (F-BAR) proteins is regulated by autoinhibitory interactions between their SRC homology 3 (SH3) and F-BAR domains. The structural basis of autoregulation, and whether it affects interactions of SH3 domains with other cellular ligands, remain unclear. Here we used single-particle electron microscopy to determine the structure of the F-BAR protein Nervous Wreck (Nwk) in both soluble and membrane-bound states. On membrane binding, Nwk SH3 domains do not completely dissociate from the F-BAR dimer, but instead shift from its concave surface to positions on either side of the dimer. Unexpectedly, along with controlling membrane binding, these autoregulatory interactions inhibit the ability of Nwk-SH3a to activate Wiskott-Aldrich syndrome protein (WASp)/actin related protein (Arp) 2/3-dependent actin filament assembly. In Drosophila neurons, Nwk autoregulation restricts SH3a domain-dependent synaptopod formation, synaptic growth, and actin organization. Our results define structural rearrangements in Nwk that control F-BAR-membrane interactions as well as SH3 domain activities, and suggest that these two functions are tightly coordinated in vitro and in vivo.
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