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Kumar A, Larrea D, Pero ME, Infante P, Conenna M, Shin GJE, Grueber WB, Di Marcotullio L, Area-Gomez E, Bartolini F. MFN2-dependent recruitment of ATAT1 coordinates mitochondria motility with alpha-tubulin acetylation and is disrupted in CMT2A. bioRxiv 2023:2023.03.15.532838. [PMID: 36993604 PMCID: PMC10055074 DOI: 10.1101/2023.03.15.532838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Acetylated microtubules play key roles in the regulation of mitochondria dynamics. It has however remained unknown if the machinery controlling mitochondria dynamics functionally interacts with the alpha-tubulin acetylation cycle. Mitofusin-2 (MFN2), a large GTPase residing in the mitochondrial outer membrane and mutated in Charcot-Marie-Tooth type 2 disease (CMT2A), is a regulator of mitochondrial fusion, transport and tethering with the endoplasmic reticulum. The role of MFN2 in regulating mitochondrial transport has however remained elusive. Here we show that mitochondrial contacts with microtubules are sites of alpha-tubulin acetylation, which occurs through the MFN2-mediated recruitment of alpha-tubulin acetyltransferase 1 (ATAT1). We discover that this activity is critical for MFN2-dependent regulation of mitochondria transport, and that axonal degeneration caused by CMT2A MFN2 associated mutations, R94W and T105M, may depend on the inability to release ATAT1 at sites of mitochondrial contacts with microtubules. Our findings reveal a function for mitochondria in regulating acetylated alpha-tubulin and suggest that disruption of the tubulin acetylation cycle play a pathogenic role in the onset of MFN2-dependent CMT2A.
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Odierna GL, Kerwin SK, Harris LE, Shin GJE, Lavidis NA, Noakes PG, Millard SS. Dscam2 suppresses synaptic strength through a PI3K-dependent endosomal pathway. J Cell Biol 2020; 219:151621. [PMID: 32259198 PMCID: PMC7265308 DOI: 10.1083/jcb.201909143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 09/24/2019] [Revised: 02/19/2020] [Accepted: 03/05/2020] [Indexed: 11/22/2022] Open
Abstract
Dscam2 is a cell surface protein required for neuronal development in Drosophila; it can promote neural wiring through homophilic recognition that leads to either adhesion or repulsion between neurites. Here, we report that Dscam2 also plays a post-developmental role in suppressing synaptic strength. This function is dependent on one of two distinct extracellular isoforms of the protein and is autonomous to motor neurons. We link the PI3K enhancer, Centaurin gamma 1A, to the Dscam2-dependent regulation of synaptic strength and show that changes in phosphoinositide levels correlate with changes in endosomal compartments that have previously been associated with synaptic strength. Using transmission electron microscopy, we find an increase in synaptic vesicles at Dscam2 mutant active zones, providing a rationale for the increase in synaptic strength. Our study provides the first evidence that Dscam2 can regulate synaptic physiology and highlights how diverse roles of alternative protein isoforms can contribute to unique aspects of brain development and function.
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Affiliation(s)
- G Lorenzo Odierna
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Sarah K Kerwin
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Lucy E Harris
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Grace Ji-Eun Shin
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY
| | - Nickolas A Lavidis
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Peter G Noakes
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - S Sean Millard
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
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Burgos A, Honjo K, Ohyama T, Qian CS, Shin GJE, Gohl DM, Silies M, Tracey WD, Zlatic M, Cardona A, Grueber WB. Nociceptive interneurons control modular motor pathways to promote escape behavior in Drosophila. eLife 2018. [PMID: 29528286 PMCID: PMC5869015 DOI: 10.7554/elife.26016] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [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] [Indexed: 12/01/2022] Open
Abstract
Rapid and efficient escape behaviors in response to noxious sensory stimuli are essential for protection and survival. Yet, how noxious stimuli are transformed to coordinated escape behaviors remains poorly understood. In Drosophila larvae, noxious stimuli trigger sequential body bending and corkscrew-like rolling behavior. We identified a population of interneurons in the nerve cord of Drosophila, termed Down-and-Back (DnB) neurons, that are activated by noxious heat, promote nociceptive behavior, and are required for robust escape responses to noxious stimuli. Electron microscopic circuit reconstruction shows that DnBs are targets of nociceptive and mechanosensory neurons, are directly presynaptic to pre-motor circuits, and link indirectly to Goro rolling command-like neurons. DnB activation promotes activity in Goro neurons, and coincident inactivation of Goro neurons prevents the rolling sequence but leaves intact body bending motor responses. Thus, activity from nociceptors to DnB interneurons coordinates modular elements of nociceptive escape behavior.
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Affiliation(s)
- Anita Burgos
- Department of Neuroscience, Columbia University Medical Center, New York, United States
| | - Ken Honjo
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Tomoko Ohyama
- Department of Biology, McGill University, Montreal, Canada
| | - Cheng Sam Qian
- Department of Neuroscience, Columbia University Medical Center, New York, United States
| | - Grace Ji-Eun Shin
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
| | - Daryl M Gohl
- University of Minnesota Genomics Center, Minneapolis, United States
| | - Marion Silies
- European Neuroscience Institute Göttingen, Göttingen, Germany
| | - W Daniel Tracey
- The Linda and Jack Gill Center for Biomolecular Science, Indiana University, Bloomington, United States.,Department of Biology, Indiana University, Bloomington, United States
| | - Marta Zlatic
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Albert Cardona
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Wesley B Grueber
- Department of Neuroscience, Columbia University Medical Center, New York, United States.,Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, United States
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Tadros W, Xu S, Akin O, Yi CH, Shin GJE, Millard SS, Zipursky SL. Dscam Proteins Direct Dendritic Targeting through Adhesion. Neuron 2016; 89:480-93. [PMID: 26844831 DOI: 10.1016/j.neuron.2015.12.026] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 11/11/2015] [Accepted: 12/07/2015] [Indexed: 11/17/2022]
Abstract
Cell recognition molecules are key regulators of neural circuit assembly. The Dscam family of recognition molecules in Drosophila has been shown to regulate interactions between neurons through homophilic repulsion. This is exemplified by Dscam1 and Dscam2, which together repel dendrites of lamina neurons, L1 and L2, in the visual system. By contrast, here we show that Dscam2 directs dendritic targeting of another lamina neuron, L4, through homophilic adhesion. Through live imaging and genetic mosaics to dissect interactions between specific cells, we show that Dscam2 is required in L4 and its target cells for correct dendritic targeting. In a genetic screen, we identified Dscam4 as another regulator of L4 targeting which acts with Dscam2 in the same pathway to regulate this process. This ensures tiling of the lamina neuropil through heterotypic interactions. Thus, different combinations of Dscam proteins act through distinct mechanisms in closely related neurons to pattern neural circuits.
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Affiliation(s)
- Wael Tadros
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Shuwa Xu
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Orkun Akin
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Caroline H Yi
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Grace Ji-Eun Shin
- School of Biomedical Sciences, The University of Queensland, Brisbane QLD 4072, Australia
| | - S Sean Millard
- School of Biomedical Sciences, The University of Queensland, Brisbane QLD 4072, Australia
| | - S Lawrence Zipursky
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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Li JSS, Shin GJE, Millard SS. Neuronal cell-type-specific alternative splicing: A mechanism for specifying connections in the brain? Neurogenesis (Austin) 2015; 2:e1122699. [PMID: 27606331 PMCID: PMC4973604 DOI: 10.1080/23262133.2015.1122699] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 11/16/2015] [Indexed: 02/05/2023]
Abstract
Alternative splicing (AS) allows a single gene to generate multiple protein isoforms. It has been hypothesized that AS plays a role in brain wiring by increasing the number of cell recognition molecules necessary for forming connections between neurons. Many studies have characterized isoform expression patterns of various genes in the brain, but very few have addressed whether specific isoforms play a functional role in neuronal wiring. In our recent work, we reported the cell-type-specific AS of the cell recognition molecule Dscam2. Exclusive expression of Dscam2 isoforms allows tightly associated neurons to signal repulsion selectively within the same cell-types, without interfering with one another. We show that preventing cell-specific isoform expression in 2 closely associated neurons disrupts their axon terminal morphology. We propose that the requirement for isoform specificity extends to synapses and discuss experiments that can test this directly. Factors that regulate Dscam2 cell-type-specific AS likely regulate the splicing of many genes involved in neurodevelopment. These regulators of alternative splicing may act broadly to control many genes involved in the development of specific neuron types. Identifying these factors is a key step in understanding how AS contributes to the brain connectome.
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Affiliation(s)
- Joshua Shing Shun Li
- School of Biomedical Sciences; The University of Queensland ; Brisbane, QLD, Australia
| | - Grace Ji-Eun Shin
- School of Biomedical Sciences; The University of Queensland ; Brisbane, QLD, Australia
| | - S Sean Millard
- School of Biomedical Sciences; The University of Queensland ; Brisbane, QLD, Australia
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