Regulation of Synapse Morphogenesis in Drosophila

Summary

Principal Investigator: David L Van Vactor
Abstract: DESCRIPTION (provided by applicant): Dysfunction in the molecular pathways that regulate synapse form and function leads to a number of neurological disorders, including epilepsy, autism and mental retardation. Our goal is to explore the molecular machinery that mediates synapse development and morphogenesis. This fundamental knowledge will be important for our understanding of neurological disease and for the conception of future therapeutic tools. Using the Drosophila neuromuscular junction (NMJ) as a genetic model system, we have discovered that miR- 8, a member of the highly conserved miR-200 family of microRNAs (miRNAs), is essential for the normal growth and complexity of the synapse. Animals lacking miR-8 display NMJ defects at different stages of development. During larval stages, when NMJs dramatically expand under control of multiple stimuli and regulatory pathways, miR-8 is required in muscle cells to promote the growth of presynaptic terminals. Our analysis suggests that miR-8 is required for the normal architecture of the cytomatrix which defines subsynaptic reticulum (SSR) of the NMJ, a structure analogous to the postsynaptic density marked by PSD-95 in mammals. Multiple screens to define downstream effectors suggest that miR-8 regulates the expression of several target genes implicated in synaptogenesis and cytoskeletal biology. To better define the mechanisms downstream of miR-8, we have shown that postsynaptic repression of the actin-associated protein Enabled (Ena) plays an important role in controlling NMJ growth in late larval stages, consistent with the localization of Ena to the SSR. Ena is predicted to be a direct target of miR-8, and controls aspects of cytoskeletal structure and dynamics during cell movement and cell junction formation, but its role(s) at the synapse are not understood. Preliminary data also indicate that although miR-8 is expressed in the central nervous system (CNS), its activity is somehow suppressed in neurons relative to other tissues. Moreover, genetic epistasis reveals that miR-8 is required for NMJ expansion induced by activation of a key presynaptic pathway that limits synapse morphogenesis (the Fragile-X Mental Retardation gene, FMR1), suggesting that some type of trans- synaptic communication is involved upstream of postsynaptic miR-8. Together, these findings reveal a fascinating mechanism that regulates synapse development, and a wonderful opportunity to exploit a powerful and well-defined model system to understand the logic of miRNA control over synapse form and function. However, many additional studies will be required to define the developmental, cellular and molecular mechanisms required for miR-8 to exert its effects at the NMJ. PUBLIC HEALTH RELEVANCE: Recent insights reveal that microRNAs provide essential regulatory mechanisms during synapse development. Dysfunction in the molecules and pathways that control synaptic morphogenesis leads to neurological disorders such as mental retardation and autism, however, our understanding of the regulatory mechanisms upstream is limited. We will determine the strategy by which Drosophila miR-8 promotes synapse formation as a model to better define the logic of pathways upstream and downstream of synaptic microRNAs.
Funding Period: 2010-04-01 - 2015-03-31
more information: NIH RePORT

Top Publications

  1. pmc Transgenic microRNA inhibition with spatiotemporal specificity in intact organisms
    Carlos M Loya
    Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
    Nat Methods 6:897-903. 2009
  2. pmc Understanding neuronal connectivity through the post-transcriptional toolkit
    Carlos M Loya
    Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
    Genes Dev 24:625-35. 2010
  3. pmc Parallel genetic and proteomic screens identify Msps as a CLASP-Abl pathway interactor in Drosophila
    L A Lowery
    Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
    Genetics 185:1311-25. 2010
  4. pmc miR-132 enhances dendritic morphogenesis, spine density, synaptic integration, and survival of newborn olfactory bulb neurons
    Manavendra Pathania
    Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut, United States of America
    PLoS ONE 7:e38174. 2012
  5. pmc A genome-wide transgenic resource for conditional expression of Drosophila microRNAs
    Fernando Bejarano
    Sloan Kettering Institute, Department of Developmental Biology, 1275 York Avenue, New York, NY 10065, USA
    Development 139:2821-31. 2012
  6. pmc MicroRNAs shape the neuronal landscape
    Elizabeth McNeill
    Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
    Neuron 75:363-79. 2012
  7. pmc Multiparametric analysis of CLASP-interacting protein functions during interphase microtubule dynamics
    Jennifer B Long
    Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
    Mol Cell Biol 33:1528-45. 2013
  8. pmc Genetic and functional studies implicate synaptic overgrowth and ring gland cAMP/PKA signaling defects in the Drosophila melanogaster neurofibromatosis-1 growth deficiency
    James A Walker
    Massachusetts General Hospital Center for Cancer Research and Harvard Medical School, Charlestown, Massachusetts, United States of America Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
    PLoS Genet 9:e1003958. 2013
  9. pmc miR-8 controls synapse structure by repression of the actin regulator enabled
    Carlos M Loya
    Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
    Development 141:1864-74. 2014

Research Grants

Detail Information

Publications9

  1. pmc Transgenic microRNA inhibition with spatiotemporal specificity in intact organisms
    Carlos M Loya
    Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
    Nat Methods 6:897-903. 2009
    ..Given that miR-SPs rely on a bipartite modular expression system, they could be used to elucidate the endogenous function of microRNAs in any species in which conditional expression can be achieved...
  2. pmc Understanding neuronal connectivity through the post-transcriptional toolkit
    Carlos M Loya
    Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
    Genes Dev 24:625-35. 2010
    ..In this review, we describe recent advances in understanding how post-transcriptional regulatory mechanisms refine the proteomic complexity required for the assembly of intricate and specific neural networks...
  3. pmc Parallel genetic and proteomic screens identify Msps as a CLASP-Abl pathway interactor in Drosophila
    L A Lowery
    Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
    Genetics 185:1311-25. 2010
    ..Moreover, we show that Msps functions during axon guidance and antagonizes both CLASP and Abl activity. Our data suggest a model in which CLASP and Msps converge in an antagonistic balance in the Abl signaling pathway...
  4. pmc miR-132 enhances dendritic morphogenesis, spine density, synaptic integration, and survival of newborn olfactory bulb neurons
    Manavendra Pathania
    Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut, United States of America
    PLoS ONE 7:e38174. 2012
    ..miR-132 overexpression in transplanted neurons may thus hold promise for enhancing neuronal survival and improving the outcome of transplant therapies...
  5. pmc A genome-wide transgenic resource for conditional expression of Drosophila microRNAs
    Fernando Bejarano
    Sloan Kettering Institute, Department of Developmental Biology, 1275 York Avenue, New York, NY 10065, USA
    Development 139:2821-31. 2012
    ..By extension, these data suggest that the deregulation of individual miRNAs in other animals may frequently yield relatively specific phenotypes during disease conditions...
  6. pmc MicroRNAs shape the neuronal landscape
    Elizabeth McNeill
    Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
    Neuron 75:363-79. 2012
    ..Here we consider recent advances in the study of microRNA-mediated regulation of synaptic form and function...
  7. pmc Multiparametric analysis of CLASP-interacting protein functions during interphase microtubule dynamics
    Jennifer B Long
    Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
    Mol Cell Biol 33:1528-45. 2013
    ..Using these data, we identify subnetworks of proteins with novel yet overlapping MT-regulatory roles and also uncover subtle distinctions between the functions of proteins previously thought to act via similar mechanisms...
  8. pmc Genetic and functional studies implicate synaptic overgrowth and ring gland cAMP/PKA signaling defects in the Drosophila melanogaster neurofibromatosis-1 growth deficiency
    James A Walker
    Massachusetts General Hospital Center for Cancer Research and Harvard Medical School, Charlestown, Massachusetts, United States of America Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
    PLoS Genet 9:e1003958. 2013
    ....
  9. pmc miR-8 controls synapse structure by repression of the actin regulator enabled
    Carlos M Loya
    Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
    Development 141:1864-74. 2014
    ..Together, these findings suggest that miR-8 limits the expansion of presynaptic terminals during larval synapse development through regulation of postsynaptic actin assembly that is independent of changes in synapse physiology. ..

Research Grants30

  1. The MicroRNA Pathway in Translational Regulation of Neuronal Development
    Fen Biao Gao; Fiscal Year: 2013
    ..PUBLIC HEALTH RELEVANCE: In this proposal, we will investigate the roles of some tiny RNAs, called microRNAs, in the development of the nervous system. We will use fruitfly as our primary model system for all the proposed studies. ..
  2. The Wingless transduction pathway in synapse development
    VIVIAN G BUDNIK; Fiscal Year: 2013
    ....
  3. Glutamate receptor recruitment to new synapses in vivo
    PHILIP ERIC WASHBOURNE; Fiscal Year: 2013
    ..Our research will help understand the mechanisms by which synapses form and bring us closer to identifying the molecular deficits in individuals with autism and mental retardation. ..
  4. Genetic and Developmental Analyses of Fragile X Mental Retardation Protein
    Kendal Broadie; Fiscal Year: 2013
    ..My lab is the only lab poised to pursue this work, and I truly believe we can aid enormously in providing understanding and devising treatments for this most common heritable cause of cognitive dysfunction and autism spectrum disorder. ..
  5. GABAA Receptor-Interacting Proteins
    Angel L De Blas; Fiscal Year: 2013
    ....
  6. Role of PAR-1 Kinase in Synaptogenesis
    Bingwei Lu; Fiscal Year: 2013
    ..abstract_text> ..
  7. Vermont Center on Behavior and Health
    Stephen T Higgins; Fiscal Year: 2013
    ..S. public health. ..
  8. Molecular bases of BK channel function and localization
    Zhao Wen Wang; Fiscal Year: 2013
    ..Such information is potentially of great value to understanding the molecular bases of BK channel-related diseases, and to identifying candidate pharmacological targets for the treatment and management of these diseases. ..