During embryonic development neurons extend processes containing growth cones that locate, recognize, and contact the appropriate targets. A synapse forms, motility ceases and a signal is sent to the cell body that elicits the synthesis of proteins to consolidate and then maintain the synaptic ending. Neither the molecules involved in recognition of the target nor the nature of the communicating signal is known. Our goal is to define these two processes at the molecular level and we have preliminary evidence that glycoproteins are involved in both. Molecules that mediate recognition are present on the growth cone. We recently succeeded in isolating growth cones from a single population of Aplysia motorneurons. Analyses revealed a glycopeptide (GPwga) that is associated with a glycoprotein exposed on the surface of the growth cones. GPwga contain one or more oligosaccharide chains that bind to certain types of muscle cells. We hypothesize that these oligosaccharides are involved in target recognition. We intend to characterize the oligosaccharides and determine if they are able to interfere with the formation of neuromuscular junctions between identified motorneurons and their target muscles in vitro. Although almost nothing is known about the way in which axons and terminals communicate with the soma, it is clear that such communication exists since events such as axotomy, denenervation, etc. elicit changes in somatic protein synthesis. We have injected 3H-monosaccharides directly into the axon of the giant neuron R2 and found that five proteins are glycosylated in the axon. Some of these are subsequently transported toward the cell body. Partial characterization of these glycoproteins suggests the presence of single O-linked N-acetylglucosamine, a modification that is found on transcriptional factors in the nucleus. Consequently, we will test the hypothesis that proteins glycosylated in the axon are transported to the nucleus where they act as signals from the periphery. We have shown that axotomy of Aplysia neurons has affects on protein synthesis that are consistant and quantifiable. We will axotomize the R2 axon to see if it alters the glycosylation of the axonal species and will also modify the glycosylated species, by injecting galactosyl transferase and UDP-galactose into the axon, to see if we can interfere with the signal to the cell soma.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
2R01NS022150-04A2
Application #
3404193
Study Section
Neurological Sciences Subcommittee 1 (NLS)
Project Start
1985-04-01
Project End
1994-03-31
Budget Start
1990-04-01
Budget End
1991-03-31
Support Year
4
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Columbia University (N.Y.)
Department
Type
Schools of Medicine
DUNS #
064931884
City
New York
State
NY
Country
United States
Zip Code
10027
Sung, Y J; Chiu, D T W; Ambron, R T (2006) Activation and retrograde transport of protein kinase G in rat nociceptive neurons after nerve injury and inflammation. Neuroscience 141:697-709
Sung, Ying-Ju; Wu, Fang; Schacher, Samuel et al. (2006) Synaptogenesis regulates axotomy-induced activation of c-Jun-activator protein-1 transcription. J Neurosci 26:6439-49
Colby, Geoffrey P; Sung, Ying-Ju; Ambron, Richard T (2005) mRNAs encoding the Aplysia homologues of fasciclin-I and beta-thymosin are expressed only in the second phase of nerve injury and are differentially segregated in axons regenerating in vitro and in vivo. J Neurosci Res 82:484-98
Sung, Ying-Ju; Ambron, Richard T (2004) Pathways that elicit long-term changes in gene expression in nociceptive neurons following nerve injury: contributions to neuropathic pain. Neurol Res 26:195-203
Sung, Ying-Ju; Walters, Edgar T; Ambron, Richard T (2004) A neuronal isoform of protein kinase G couples mitogen-activated protein kinase nuclear import to axotomy-induced long-term hyperexcitability in Aplysia sensory neurons. J Neurosci 24:7583-95
Lin, Hana; Bao, Jianxin; Sung, Ying-Ju et al. (2003) Rapid electrical and delayed molecular signals regulate the serum response element after nerve injury: convergence of injury and learning signals. J Neurobiol 57:204-20
Farr, M; Zhu, D F; Povelones, M et al. (2001) Direct interactions between immunocytes and neurons after axotomy in Aplysia. J Neurobiol 46:89-96
Sung, Y J; Povelones, M; Ambron, R T (2001) RISK-1: a novel MAPK homologue in axoplasm that is activated and retrogradely transported after nerve injury. J Neurobiol 47:67-79
Zhang, X P; Ambron, R T (2000) Positive injury signals induce growth and prolong survival in Aplysia neurons. J Neurobiol 45:84-94
Farr, M; Mathews, J; Zhu, D F et al. (1999) Inflammation causes a long-term hyperexcitability in the nociceptive sensory neurons of Aplysia. Learn Mem 6:331-40

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