A central problem in neurobiology is to determine how the complex networks of neuronal connections, that underlie the functioning of the nervous system, are established. This intricate pattern is generated, at least in part, when neuronal cell bodies and their axons migrate to their targets, guided by diffusible chemotropic cues. The long term goal for my laboratory is to understand how cells detect and orient themselves in gradients of guidance cues, and transduce this information intracellularly into changes in shape and motility that lead to directed migrations. Netrin-1 is an example of such a guidance cue, and two families of receptors that specify attractant and repellent responses to netrin-1 have been identified. The attraction of a cell or axon toward netrin-1 is mediated by DCC (Deleted in Colorectal Carcinoma). Studies in C. elegans demonstrate that repulsion away from netrin-1 is specified by UNC5 receptors, and that UNC5 functions together with DCC to mediate this repulsion. In the preliminary data, it is shown that UNC5H and DCC physically interact to form a repellent protein complex. Based on these studies, the major hypothesis of the grant proposal is that vertebrate homologs of UNC5 (UNC5Hs), together with DCC, mediate netrin-1 dependent chemorepulsion in vertebrates in vivo. To address the hypothesis, the specific aims of this proposal are two-fold. I) To define the in vivo role of the UNC5H/DCC complex in directing netrin-1 mediated repulsion. Studies are proposed on the role of netrin-1 in guiding the migration of cerebellar granule cells. These studies examine the consequences of netrin- 1 loss-of-function and gain-of-function in vivo, and the migration of cerebellar granule cells in vitro. II) To understand the molecular mechanisms that specify repulsion versus attraction, the molecules that bind to UNC5Hs and transduce a repellent signal will be identified using yeast two-hybrid and affinity chromatography approaches. The function(s) of these interacting proteins in mediating repulsion in response to netrin-1 will be tested in axon guidance or cell migration assays. These experiments provide the foundation for understanding how cells translate a netrin-1 signal into directed migrations.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS039572-03
Application #
6531110
Study Section
Special Emphasis Panel (ZRG1-MDCN-7 (01))
Program Officer
Tagle, Danilo A
Project Start
2000-03-09
Project End
2004-02-29
Budget Start
2002-03-01
Budget End
2003-02-28
Support Year
3
Fiscal Year
2002
Total Cost
$249,634
Indirect Cost
Name
University of California Santa Cruz
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
City
Santa Cruz
State
CA
Country
United States
Zip Code
95064
McKenna, William L; Wong-Staal, Caroline; Kim, Grace C et al. (2008) Netrin-1-independent adenosine A2b receptor activation regulates the response of axons to netrin-1 by controlling cell surface levels of UNC5A receptors. J Neurochem 104:1081-90
Bartoe, Joseph L; McKenna, William L; Quan, Tiffani K et al. (2006) Protein interacting with C-kinase 1/protein kinase Calpha-mediated endocytosis converts netrin-1-mediated repulsion to attraction. J Neurosci 26:3192-205
Williams, Megan E; Lu, Xiaowei; McKenna, William L et al. (2006) UNC5A promotes neuronal apoptosis during spinal cord development independent of netrin-1. Nat Neurosci 9:996-8
Sasaki, Aya; Hinck, Lindsay; Watanabe, Ken (2005) RumMAGE-D the members: structure and function of a new adaptor family of MAGE-D proteins. J Recept Signal Transduct Res 25:181-98
Williams, Megan E; Wu, Sareina C-Y; McKenna, William L et al. (2003) Surface expression of the netrin receptor UNC5H1 is regulated through a protein kinase C-interacting protein/protein kinase-dependent mechanism. J Neurosci 23:11279-88
Williams, Megan E; Strickland, Phyllis; Watanabe, Ken et al. (2003) UNC5H1 induces apoptosis via its juxtamembrane region through an interaction with NRAGE. J Biol Chem 278:17483-90