The growth cone at the distal tip of the extending axon is a specialized sensory apparatus which transduces extracellular signals into growth along appropriate pathways to correct synaptic targets. Its proper function is crucial to nervous system development and hence function. This proposal seeks a molecular understanding of the signal transduction mechanisms at the neuronal growth cone. Particular emphasis is focused on the action of collapsin-1, a member of the semaphorin family of proteins recently recognized to inhibit axonal extension and terminal arborization. The essential role of monomeric G proteins of the rho family and of heterotrimeric G proteins in dorsal root ganglion (DRG) growth cone signal transduction will be examined by introducing mutant activated and dominant negative proteins. The hypothesis that GAP-43 augments sensitivity of the growth cone to extracellular signals will be examined in cultured DRG neurons from mice with a targeted deletion mutation in the GAP-43 gene. A recently identified family of neuronal CRMP proteins appear to be required for collapsin-1 inhibition of growth cone function. This project will further define CRMP action by identifying proteins interacting with CRMP, exploring enzymatic activities of CRMP and comparing the properties of different CRMP family members. Neurite outgrowth and collapsin-1 sensitivity of cells overexpressing different forms of CRMP will be examined. A collapsin-alkaline-phosphatase fusion protein will be used to identify collapsin binding proteins which may serve as collapsin receptors in the neuronal growth cone. Once such receptors are identified their interaction with CRMP, GAP-43, and G proteins can be delineated. Together these experiments provide a detailed description of the molecular events which underlie the growth cone responsiveness to extracellular inhibitory signals such as collapsin-1. Knowledge of these pathways provides necessary groundwork for understanding the pathophysiology of human developmental abnormalities of the brain. The same mechanisms are likely to function during adult nervous system injury and improve function in degenerative neurologic diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS033020-06
Application #
2735639
Study Section
Neurology B Subcommittee 2 (NEUB)
Program Officer
Spinella, Giovanna M
Project Start
1993-09-17
Project End
2000-06-30
Budget Start
1998-07-01
Budget End
1999-06-30
Support Year
6
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Yale University
Department
Neurology
Type
Schools of Medicine
DUNS #
082359691
City
New Haven
State
CT
Country
United States
Zip Code
06520
Schwab, Martin E; Strittmatter, Stephen M (2014) Nogo limits neural plasticity and recovery from injury. Curr Opin Neurobiol 27:53-60
Huebner, Eric A; Kim, Byung G; Duffy, Philip J et al. (2011) A multi-domain fragment of Nogo-A protein is a potent inhibitor of cortical axon regeneration via Nogo receptor 1. J Biol Chem 286:18026-36
Wang, Xingxing; Budel, Stephane; Baughman, Kenneth et al. (2009) Ibuprofen enhances recovery from spinal cord injury by limiting tissue loss and stimulating axonal growth. J Neurotrauma 26:81-95
Wang, L H; Kalb, R G; Strittmatter, S M (1999) A PDZ protein regulates the distribution of the transmembrane semaphorin, M-SemF. J Biol Chem 274:14137-46
Xie, R; Li, L; Goshima, Y et al. (1995) An activated mutant of the alpha subunit of G(o) increases neurite outgrowth via protein kinase C. Brain Res Dev Brain Res 87:77-86
Strittmatter, S M; Igarashi, M; Fishman, M C (1994) GAP-43 amino terminal peptides modulate growth cone morphology and neurite outgrowth. J Neurosci 14:5503-13