The purpose of the research proposed in this grant is to generate tools that will allow endogenous synaptic proteins to be visualized in neurons in vivo. Previously we have generated recombinant antibodies known as FingRs (Fibronectin intrabodies generated with mRNA display) that can be expressed in living neurons where they label endogenous target proteins noninvasively and with high fidelity. Furthermore, a transcriptional regulation system controls the expression levels of FingRs so that they are expressed at precisely the same level as their endogenous counterparts, insuring low background. In this grant we will generate transgenic mice that express fluorescent protein-fused FingRs that recognize synaptic proteins. Synaptic proteins in individual neurons in the brains of these mice can be visualized in vivo in real time. In turn, this will allow events at the molecular level to be correlated with events at the cellular, circuit and whole animal level. In particular, by mapping the locations and amounts of synaptic proteins in neurons, it will be possible to monitor the strength of both synaptic inputs and outputs in living neurons. The ability to monitor synaptic strength will be very useful for studying diseases associated with aberrant synaptic connectivity including schizophrenia, mental retardation and autism.

Public Health Relevance

Previously we have generated recombinant antibodies that allow endogenous Gephyrin and PSD95 to be visualized in living cells. The research proposed in this grant will extend our previous results to allow synaptic proteins to be visualized in intac animals.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Molecular Neurogenetics Study Section (MNG)
Program Officer
Stewart, Randall R
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Southern California
Schools of Arts and Sciences
Los Angeles
United States
Zip Code
Feng, Shanxi; Arnold, Don B (2016) Techniques for studying protein trafficking and molecular motors in neurons. Cytoskeleton (Hoboken) 73:508-15
Kannan, Madhuvanthi; Gross, Garrett G; Arnold, Don B et al. (2016) Visual Deprivation During the Critical Period Enhances Layer 2/3 GABAergic Inhibition in Mouse V1. J Neurosci 36:5914-9
Gross, Garrett G; Straub, Christoph; Perez-Sanchez, Jimena et al. (2016) An E3-ligase-based method for ablating inhibitory synapses. Nat Methods 13:673-8
Barcomb, Kelsey; Goodell, Dayton J; Arnold, Don B et al. (2015) Live imaging of endogenous Ca²⁺/calmodulin-dependent protein kinase II in neurons reveals that ischemia-related aggregation does not require kinase activity. J Neurochem 135:666-73
Marotta, Nicholas P; Lin, Yu Hsuan; Lewis, Yuka E et al. (2015) O-GlcNAc modification blocks the aggregation and toxicity of the protein α-synuclein associated with Parkinson's disease. Nat Chem 7:913-20
Arnold, Don B; Gallo, Gianluca (2014) Structure meets function: actin filaments and myosin motors in the axon. J Neurochem 129:213-20
Gross, Garrett G; Junge, Jason A; Mora, Rudy J et al. (2013) Recombinant probes for visualizing endogenous synaptic proteins in living neurons. Neuron 78:971-85