The long-term objective of this study is to understand the molecular and cellular mechanisms that underlie axon development and the establishment of neuronal polarity. The ability of neuronal cells to polarize is essential for the organization of the nervous system and has profound functional implications. Typically, a neuron polarizes to elaborate one long axon and multiple, shorter dendrites so as to transmit and receive information and establish the circuitry that is critical for normal cognitive functions. Moreover, abundant evidence indicates that loss of neuronal polarity is associated with numerous neurodegenerative diseases. Thus understanding the machineries involved in neuronal polarization is of utmost importance to human health. The initial event in establishing a polarized neuron is the development of a single axon. We have recently identified DOCK7 as a novel activator of Rac GTPases, and demonstrated that the protein plays a crucial role in early steps of axon development. Moreover, our data have unveiled a link between DOCK7 and the microtubule regulatory protein, stathmin, and highlight the contribution of microtubule network regulation to axon development. These findings provide a unique framework for obtaining novel insight into the molecular and cellular underpinnings of axon development. This application aims to delineate further the role and mechanism of DOCK7 function in this important developmental step. Towards these goals, the first specific aim will characterize the signaling pathway that mediates the effect of DOCK7 on stathmin phosphorylation and axon development.
Specific aim 2 focuses on the regulation of DOCK7, including the mechanisms that define how DOCK7 becomes activated and selectively localized in the nascent axon. Molecular, biochemical, and cell biological approaches will be used to address these objectives. The third specific aim will identify DOCK7-interacting proteins important for its function in neuronal polarization, by using biochemical purification techniques and mass spectrometry, and the yeast two-hybrid method. Finally, specific aim 4 scrutinizes the role of DOCK7 in the polarization of migrating cortical neurons in brain slices. To this end, in utero electroporation technology and two-photon microscopy will be employed. Information gained from these studies will greatly contribute to understanding the mechanisms that underlie axon development and neuronal polarization. As such, they will have significant implications for understanding biomedically relevant processes, including neuronal development, associated cognitive function, nerve regeneration and neurodegenerative disease.

Public Health Relevance

The ability of neuronal cells to polarize - i.e. to elaborate one axon and multiple, shorter dendrites - is essential for the organization of the nervous system and has profound functional ramifications for normal cognitive functions and the regeneration of nerve cells. The proposed studies are aimed at understanding the molecular and cellular mechanisms that underlie axon development and neuronal polarization. As such, they will have significant implications for numerous biomedically relevant processes, including neuronal development, associated cognitive function, nerve regeneration and neurodegenerative disease, and may provide the basis for developing therapeutic agents for the generation and regeneration of new and damaged axons, respectively.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
5R01MH082808-03
Application #
7800250
Study Section
Cellular Signaling and Regulatory Systems Study Section (CSRS)
Program Officer
Panchision, David M
Project Start
2008-07-01
Project End
2013-03-31
Budget Start
2010-04-01
Budget End
2011-03-31
Support Year
3
Fiscal Year
2010
Total Cost
$391,500
Indirect Cost
Name
Cold Spring Harbor Laboratory
Department
Type
DUNS #
065968786
City
Cold Spring Harbor
State
NY
Country
United States
Zip Code
11724
Nakamuta, Shinichi; Yang, Yu-Ting; Wang, Chia-Lin et al. (2017) Dual role for DOCK7 in tangential migration of interneuron precursors in the postnatal forebrain. J Cell Biol 216:4313-4330
Penzo, Mario A; Robert, Vincent; Tucciarone, Jason et al. (2015) The paraventricular thalamus controls a central amygdala fear circuit. Nature 519:455-9
Krishnan, Navasona; Krishnan, Keerthi; Connors, Christopher R et al. (2015) PTP1B inhibition suggests a therapeutic strategy for Rett syndrome. J Clin Invest 125:3163-77
Murray, D W; Didier, S; Chan, A et al. (2014) Guanine nucleotide exchange factor Dock7 mediates HGF-induced glioblastoma cell invasion via Rac activation. Br J Cancer 110:1307-15
Tai, Yilin; Janas, Justyna A; Wang, Chia-Lin et al. (2014) Regulation of chandelier cell cartridge and bouton development via DOCK7-mediated ErbB4 activation. Cell Rep 6:254-63
Nakano-Kobayashi, Akiko; Tai, Yilin; Nadif Kasri, Nael et al. (2014) The X-linked mental retardation protein OPHN1 interacts with Homer1b/c to control spine endocytic zone positioning and expression of synaptic potentiation. J Neurosci 34:8665-71
Anne, Sandrine L; Govek, Eve-Ellen; Ayrault, Olivier et al. (2013) WNT3 inhibits cerebellar granule neuron progenitor proliferation and medulloblastoma formation via MAPK activation. PLoS One 8:e81769
Zhang, Xiaoqun Catherine; Piccini, Antonella; Myers, Michael P et al. (2012) Functional analysis of the protein phosphatase activity of PTEN. Biochem J 444:457-64
Kang, Hara; Davis-Dusenbery, Brandi N; Nguyen, Peter H et al. (2012) Bone morphogenetic protein 4 promotes vascular smooth muscle contractility by activating microRNA-21 (miR-21), which down-regulates expression of family of dedicator of cytokinesis (DOCK) proteins. J Biol Chem 287:3976-86
Yang, Yu-Ting; Wang, Chia-Lin; Van Aelst, Linda (2012) DOCK7 interacts with TACC3 to regulate interkinetic nuclear migration and cortical neurogenesis. Nat Neurosci 15:1201-10

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