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DePew AT, Bruckner JJ, O'Connor-Giles KM, Mosca TJ. Neuronal LRP4 directs the development, maturation, and cytoskeletal organization of Drosophila peripheral synapses. Development 2024:dev.202517. [PMID: 38738619 DOI: 10.1242/dev.202517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 05/13/2024] [Indexed: 05/14/2024]
Abstract
Synaptic development requires multiple signaling pathways to ensure successful connections. Transmembrane receptors are optimally positioned to connect the synapse and the rest of the neuron, often acting as synaptic organizers to synchronize downstream events. One such organizer, the LDL receptor-related protein LRP4, is a cell surface receptor most well-studied postsynaptically at mammalian neuromuscular junctions. Recent work, however, identified emerging roles, but how LRP4 acts as a presynaptic organizer and the downstream mechanisms of LRP4 are not well understood. Here we show LRP4 functions presynaptically at Drosophila neuromuscular synapses, acting in motoneurons to instruct pre- and postsynaptic development. Loss of presynaptic LRP4 results in multiple defects, impairing active zone organization, synapse growth, physiological function, microtubule organization, synaptic ultrastructure, and synapse maturation. We further demonstrate that LRP4 promotes most aspects of presynaptic development via a downstream SR-protein kinase, SRPK79D. These data demonstrate a function for presynaptic LRP4 as a peripheral synaptic organizer, highlight a downstream mechanism conserved with its CNS function in Drosophila, and underscores previously unappreciated but important developmental roles for LRP4 in cytoskeletal organization, synapse maturation, and active zone organization.
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Affiliation(s)
- Alison T DePew
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Joseph J Bruckner
- Cell and Molecular Biology Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Kate M O'Connor-Giles
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
- Carney Institute for Brain Sciencem, Brown University, Providence, RI 02912, USA
| | - Timothy J Mosca
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Philadelphia, PA 19107, USA
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DePew AT, Bruckner JJ, O’Connor-Giles KM, Mosca TJ. Neuronal LRP4 directs the development, maturation, and cytoskeletal organization of peripheral synapses. bioRxiv 2023:2023.11.03.564481. [PMID: 37961323 PMCID: PMC10635100 DOI: 10.1101/2023.11.03.564481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Synapse development requires multiple signaling pathways to accomplish the myriad of steps needed to ensure a successful connection. Transmembrane receptors on the cell surface are optimally positioned to facilitate communication between the synapse and the rest of the neuron and often function as synaptic organizers to synchronize downstream signaling events. One such organizer, the LDL receptor-related protein LRP4, is a cell surface receptor most well-studied postsynaptically at mammalian neuromuscular junctions. Recent work, however, has identified emerging roles for LRP4 as a presynaptic molecule, but how LRP4 acts as a presynaptic organizer, what roles LRP4 plays in organizing presynaptic biology, and the downstream mechanisms of LRP4 are not well understood. Here we show that LRP4 functions presynaptically at Drosophila neuromuscular synapses, acting in motor neurons to instruct multiple aspects of pre- and postsynaptic development. Loss of presynaptic LRP4 results in a range of developmental defects, impairing active zone organization, synapse growth, physiological function, microtubule organization, synaptic ultrastructure, and synapse maturation. We further demonstrate that LRP4 promotes most aspects of presynaptic development via a downstream SR-protein kinase, SRPK79D. SRPK79D overexpression suppresses synaptic defects associated with loss of lrp4. These data demonstrate a function for LRP4 as a peripheral synaptic organizer acting presynaptically, highlight a downstream mechanism conserved with its CNS function, and indicate previously unappreciated roles for LRP4 in cytoskeletal organization, synapse maturation, and active zone organization, underscoring its developmental importance.
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Affiliation(s)
- Alison T. DePew
- Dept. of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Philadelphia, PA 19107 USA
| | - Joseph J. Bruckner
- Cell and Molecular Biology Training Program, University of Wisconsin-Madison, Madison, WI 53706 USA
| | - Kate M. O’Connor-Giles
- Department of Neuroscience, Brown University, Providence, RI 02912 USA
- Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
| | - Timothy J. Mosca
- Dept. of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Philadelphia, PA 19107 USA
- Lead Contact
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Bruckner JJ, Stednitz SJ, Grice MZ, Zaidan D, Massaquoi MS, Larsch J, Tallafuss A, Guillemin K, Washbourne P, Eisen JS. The microbiota promotes social behavior by modulating microglial remodeling of forebrain neurons. PLoS Biol 2022; 20:e3001838. [PMID: 36318534 PMCID: PMC9624426 DOI: 10.1371/journal.pbio.3001838] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 09/19/2022] [Indexed: 11/06/2022] Open
Abstract
Host-associated microbiotas guide the trajectory of developmental programs, and altered microbiota composition is linked to neurodevelopmental conditions such as autism spectrum disorder. Recent work suggests that microbiotas modulate behavioral phenotypes associated with these disorders. We discovered that the zebrafish microbiota is required for normal social behavior and reveal a molecular pathway linking the microbiota, microglial remodeling of neural circuits, and social behavior in this experimentally tractable model vertebrate. Examining neuronal correlates of behavior, we found that the microbiota restrains neurite complexity and targeting of forebrain neurons required for normal social behavior and is necessary for localization of forebrain microglia, brain-resident phagocytes that remodel neuronal arbors. The microbiota also influences microglial molecular functions, including promoting expression of the complement signaling pathway and the synaptic remodeling factor c1q. Several distinct bacterial taxa are individually sufficient for normal microglial and neuronal phenotypes, suggesting that host neuroimmune development is sensitive to a feature common among many bacteria. Our results demonstrate that the microbiota influences zebrafish social behavior by stimulating microglial remodeling of forebrain circuits during early neurodevelopment and suggest pathways for new interventions in multiple neurodevelopmental disorders.
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Affiliation(s)
- Joseph J. Bruckner
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Sarah J. Stednitz
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Max Z. Grice
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Dana Zaidan
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Michelle S. Massaquoi
- Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Johannes Larsch
- Department Genes-Circuits-Behavior, Max Planck Institute of Neurobiology, Martinsried, Germany
| | - Alexandra Tallafuss
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Karen Guillemin
- Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
- Humans and the Microbiome Program, CIFAR, Toronto, Ontario, Canada
| | - Philip Washbourne
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
- * E-mail: (PW); (JSE)
| | - Judith S. Eisen
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
- * E-mail: (PW); (JSE)
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Bruckner JJ, Zhan H, Gratz SJ, Rao M, Ukken F, Zilberg G, O'Connor-Giles KM. Fife organizes synaptic vesicles and calcium channels for high-probability neurotransmitter release. J Cell Biol 2016; 216:231-246. [PMID: 27998991 PMCID: PMC5223599 DOI: 10.1083/jcb.201601098] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 10/19/2016] [Accepted: 11/29/2016] [Indexed: 11/22/2022] Open
Abstract
Fife is a Piccolo-RIM–related protein that regulates neurotransmission and motor behavior through an unknown mechanism. Here, Bruckner et al. show that Fife organizes synaptic vesicle docking and coupling to calcium channels to establish and modulate synaptic strength. The strength of synaptic connections varies significantly and is a key determinant of communication within neural circuits. Mechanistic insight into presynaptic factors that establish and modulate neurotransmitter release properties is crucial to understanding synapse strength, circuit function, and neural plasticity. We previously identified Drosophila Piccolo-RIM-related Fife, which regulates neurotransmission and motor behavior through an unknown mechanism. Here, we demonstrate that Fife localizes and interacts with RIM at the active zone cytomatrix to promote neurotransmitter release. Loss of Fife results in the severe disruption of active zone cytomatrix architecture and molecular organization. Through electron tomographic and electrophysiological studies, we find a decrease in the accumulation of release-ready synaptic vesicles and their release probability caused by impaired coupling to Ca2+ channels. Finally, we find that Fife is essential for the homeostatic modulation of neurotransmission. We propose that Fife organizes active zones to create synaptic vesicle release sites within nanometer distance of Ca2+ channel clusters for reliable and modifiable neurotransmitter release.
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Affiliation(s)
- Joseph J Bruckner
- Cell and Molecular Biology Training Program, University of Wisconsin-Madison, Madison, WI 53706
| | - Hong Zhan
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706
| | - Scott J Gratz
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706
| | - Monica Rao
- Cell and Molecular Biology Training Program, University of Wisconsin-Madison, Madison, WI 53706
| | - Fiona Ukken
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706
| | - Gregory Zilberg
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706
| | - Kate M O'Connor-Giles
- Cell and Molecular Biology Training Program, University of Wisconsin-Madison, Madison, WI 53706 .,Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706.,Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706
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Ukken FP, Bruckner JJ, Weir KL, Hope SJ, Sison SL, Birschbach RM, Hicks L, Taylor KL, Dent EW, Gonsalvez GB, O'Connor-Giles KM. BAR-SH3 sorting nexins are conserved interacting proteins of Nervous wreck that organize synapses and promote neurotransmission. J Cell Sci 2015; 129:166-77. [PMID: 26567222 PMCID: PMC4732300 DOI: 10.1242/jcs.178699] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 11/11/2015] [Indexed: 12/13/2022] Open
Abstract
Nervous wreck (Nwk) is a conserved F-BAR protein that attenuates synaptic growth and promotes synaptic function in Drosophila. In an effort to understand how Nwk carries out its dual roles, we isolated interacting proteins using mass spectrometry. We report a conserved interaction between Nwk proteins and BAR-SH3 sorting nexins, a family of membrane-binding proteins implicated in diverse intracellular trafficking processes. In mammalian cells, BAR-SH3 sorting nexins induce plasma membrane tubules that localize NWK2, consistent with a possible functional interaction during the early stages of endocytic trafficking. To study the role of BAR-SH3 sorting nexins in vivo, we took advantage of the lack of genetic redundancy in Drosophila and employed CRISPR-based genome engineering to generate null and endogenously tagged alleles of SH3PX1. SH3PX1 localizes to neuromuscular junctions where it regulates synaptic ultrastructure, but not synapse number. Consistently, neurotransmitter release was significantly diminished in SH3PX1 mutants. Double-mutant and tissue-specific-rescue experiments indicate that SH3PX1 promotes neurotransmitter release presynaptically, at least in part through functional interactions with Nwk, and might act to distinguish the roles of Nwk in regulating synaptic growth and function.
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Affiliation(s)
- Fiona P Ukken
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Joseph J Bruckner
- Cell and Molecular Biology Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Kurt L Weir
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Sarah J Hope
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Samantha L Sison
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ryan M Birschbach
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Lawrence Hicks
- Cellular Biology and Anatomy, Georgia Regents University, Augusta, GA 30912, USA
| | - Kendra L Taylor
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Erik W Dent
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Graydon B Gonsalvez
- Cellular Biology and Anatomy, Georgia Regents University, Augusta, GA 30912, USA
| | - Kate M O'Connor-Giles
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706, USA Cell and Molecular Biology Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
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Bruckner JJ, Zhan H, O'Connor-Giles KM. Advances in imaging ultrastructure yield new insights into presynaptic biology. Front Cell Neurosci 2015; 9:196. [PMID: 26052269 PMCID: PMC4440913 DOI: 10.3389/fncel.2015.00196] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 05/05/2015] [Indexed: 11/13/2022] Open
Abstract
Synapses are the fundamental functional units of neural circuits, and their dysregulation has been implicated in diverse neurological disorders. At presynaptic terminals, neurotransmitter-filled synaptic vesicles are released in response to calcium influx through voltage-gated calcium channels activated by the arrival of an action potential. Decades of electrophysiological, biochemical, and genetic studies have contributed to a growing understanding of presynaptic biology. Imaging studies are yielding new insights into how synapses are organized to carry out their critical functions. The development of techniques for rapid immobilization and preservation of neuronal tissues for electron microscopy (EM) has led to a new renaissance in ultrastructural imaging that is rapidly advancing our understanding of synapse structure and function.
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Affiliation(s)
- Joseph J Bruckner
- Cell and Molecular Biology Training Program, University of Wisconsin-Madison Madison, WI, USA
| | - Hong Zhan
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison Madison, WI, USA
| | - Kate M O'Connor-Giles
- Cell and Molecular Biology Training Program, University of Wisconsin-Madison Madison, WI, USA ; Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison Madison, WI, USA ; Laboratory of Genetics, University of Wisconsin-Madison Madison, WI, USA
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Jing L, Haas J, Chong TM, Bruckner JJ, Dann GC, Dong L, Marshak JO, McClurkan CL, Yamamoto TN, Bailer SM, Laing KJ, Wald A, Verjans GM, Koelle DM. Cross-presentation and genome-wide screening reveal candidate T cells antigens for a herpes simplex virus type 1 vaccine. J Clin Invest 2012. [DOI: 10.1172/jci65722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Jing L, Haas J, Chong TM, Bruckner JJ, Dann GC, Dong L, Marshak JO, McClurkan CL, Yamamoto TN, Bailer SM, Laing KJ, Wald A, Verjans GMGM, Koelle DM. Cross-presentation and genome-wide screening reveal candidate T cells antigens for a herpes simplex virus type 1 vaccine. J Clin Invest 2012; 122:654-73. [PMID: 22214845 DOI: 10.1172/jci60556] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 11/09/2011] [Indexed: 11/17/2022] Open
Abstract
Herpes simplex virus type 1 (HSV-1) not only causes painful recurrent oral-labial infections, it can also cause permanent brain damage and blindness. There is currently no HSV-1 vaccine. An effective vaccine must stimulate coordinated T cell responses, but the large size of the genome and the low frequency of HSV-1-specific T cells have hampered the search for the most effective T cell antigens for inclusion in a candidate vaccine. We have now developed what we believe to be novel methods to efficiently generate a genome-wide map of the responsiveness of HSV-1-specific T cells, and demonstrate the applicability of these methods to a second complex microbe, vaccinia virus. We used cross-presentation and CD137 activation-based FACS to enrich for polyclonal CD8+ T effector T cells. The HSV-1 proteome was prepared in a flexible format for analyzing both CD8+ and CD4+ T cells from study participants. Scans with participant-specific panels of artificial APCs identified an oligospecific response in each individual. Parallel CD137-based CD4+ T cell research showed discrete oligospecific recognition of HSV-1 antigens. Unexpectedly, the two HSV-1 proteins not previously considered as vaccine candidates elicited both CD8+ and CD4+ T cell responses in most HSV-1-infected individuals. In this era of microbial genomics, our methods - also demonstrated in principle for vaccinia virus for both CD8+ and CD4+ T cells - should be broadly applicable to the selection of T cell antigens for inclusion in candidate vaccines for many pathogens.
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Affiliation(s)
- Lichen Jing
- Department of Medicine, University of Washington, Seattle, Washington, USA
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