Philip Washbourne

Associate Professor, Department of Biology
Member, ION

Ph.D. Universita di Padova, Italy
B.Sc. Imperial College London, UK

Office:
334D Huestis
541-346-4138 

 

Research Interests: Molecular mechanisms of synapse formation

Overview: Information is exchanged between neurons at synapses, which are essentially specialized sites of cell-cell adhesion . A mature synapse is defined as an accumulation of synaptic vesicles within the axon, in close apposition to a dendritic membrane studded with receptors (see figure)which are held in place by a submembranous scaffold (Sheng and Kim, 2002). The formation of such an intercellular structure requires spatially and temporally controlled changes in morphology and molecular content at sites of contacts. Recent advances in subcellular fluorescence microscopy have revealed that this process involves the rapid recruitment and stabilization of both pre- and postsynaptic elements. These studies have shown that major components of the synaptic vesicle and active zone machinery travel in clusters together with other presynaptic proteins, such as calcium channels, and are rapidly recruited to new sites of contact (Ahmari et al., 2000; Zhai et al., 2001; Washbourne et al., 2002) .

On the postsynaptic side, receptor subunits and components of the scaffold or post-synaptic density (PSD) are recruited separately and with distinct time courses within minutes to hours after initial contact (Friedman et al., 2000; Bresler et al., 2001; Washbourne et al., 2002; Bresler et al., 2004)

Despite these advances the basic mechanisms by which synapse formation is induced at discrete locations and by which the molecular machinery is recruited to sites of contact remain elusive. We are currently using both mammalian primary neuronal cultures and zebrafish embryos to investigate molecules that are involved in the mechanisms of synapse formation. Techniques currently employed are live confocal imaging of fluorescently-tagged synaptic components, electron microscopy, biochemistry and molecular biology.

RECENT PUBLICATIONS

yippee like 3 (ypel3) is a novel gene required for myelinating and perineurial glia development.

PLoS Genet. 2020 Jun 16;16(6):e1008841

Authors: Blanco-Sánchez B, Clément A, Stednitz SJ, Kyle J, Peirce JL, McFadden M, Wegner J, Phillips JB, Macnamara E, Huang Y, Adams DR, Toro C, Gahl WA, Malicdan MCV, Tifft CJ, Zink EM, Bloodsworth KJ, Stratton KG, Undiagnosed Diseases Network, Koeller DM, Metz TO, Washbourne P, Westerfield M

Abstract
Hypomyelination, a neurological condition characterized by decreased production of myelin sheets by glial cells, often has no known etiology. Elucidating the genetic causes of hypomyelination provides a better understanding of myelination, as well as means to diagnose, council, and treat patients. Here, we present evidence that YIPPEE LIKE 3 (YPEL3), a gene whose developmental role was previously unknown, is required for central and peripheral glial cell development. We identified a child with a constellation of clinical features including cerebral hypomyelination, abnormal peripheral nerve conduction, hypotonia, areflexia, and hypertrophic peripheral nerves. Exome and genome sequencing revealed a de novo mutation that creates a frameshift in the open reading frame of YPEL3, leading to an early stop codon. We used zebrafish as a model system to validate that YPEL3 mutations are causative of neuropathy. We found that ypel3 is expressed in the zebrafish central and peripheral nervous system. Using CRISPR/Cas9 technology, we created zebrafish mutants carrying a genomic lesion similar to that of the patient. Our analysis revealed that Ypel3 is required for development of oligodendrocyte precursor cells, timely exit of the perineurial glial precursors from the central nervous system (CNS), formation of the perineurium, and Schwann cell maturation. Consistent with these observations, zebrafish ypel3 mutants have metabolomic signatures characteristic of oligodendrocyte and Schwann cell differentiation defects, show decreased levels of Myelin basic protein in the central and peripheral nervous system, and develop defasciculated peripheral nerves. Locomotion defects were observed in adult zebrafish ypel3 mutants. These studies demonstrate that Ypel3 is a novel gene required for perineurial cell development and glial myelination.

PMID: 32544203 [PubMed - as supplied by publisher]