During the development of the nervous system, axons are directed to their cognate synaptic targets by guidance factors that exert either a repulsive or an attractive effect onto axons and growth cones. Disturbances in the intricately regulated process of axonal pathfinding interfere with the establishment of correct synaptic connections and the formation of proper neuronal circuitry. Consequently, alterations of axonal pathfinding are thought to cause a wide variety of neurodevelopmental disorders. Netrin-1 and NGF are attractive guidance cues that induce faster growth rates in axons, as well as growth cone elaboration and attractive turning. These morphological changes are mediated by the rearrangement of the highly dynamic actin and microtubules cytoskeleton within growth cones, and a great amount of prior research has addressed the intra-axonal signaling pathways governing these cytoskeletal changes. However, besides cytoskeletal growth the process of axon elongation and growth cone elaboration requires the rapid, massive enlargement of the cell surface. The phospholipids that make up the nascent plasma membrane are anterogradely transported along the axons from the cell bodies in the form of plasma membrane precursor vesicles (PPVs). These PPVs fuse with the growth cone membrane thereby enlarging the surface of axons and growth cones in a regulated process called polarized exocytosis. Plasma membrane expansion and cytoskeletal dynamics have to occur at the same site and at the same time to achieve axon outgrowth or turning. Currently, it is unknown how this synchronicity between two seemingly separate pathways is established. The goal of this application is to understand how these two molecular pathways, cytoskeletal rearrangement and polarized exocytosis of PPVs, are integrated and co-regulated downstream of netrin-1 and NGF signaling to result in the characteristic axonal outgrowth and growth cone turning that characterize the morphological response of axons to attractive guidance cues. Based on preliminary studies, a special focus of this research proposal is to understand the functional significance of intra-axonal mRNA translation for the co-activation of both pathways. The successful completion of this research will provide a coherent view of the signaling cascades that ensure the temporal-spatial concurrence of cytoskeletal dynamics and membrane expansion within distal axons and growth cones stimulated with attractive guidance cues.

Public Health Relevance

During development, guidance molecules in the immature brain direct axons to their targets;disturbances in this process change neuronal connectivity and may underlie neurodevelopmental disorders. This research proposal is designed to elucidate the intra-axonal mechanisms governing axon outgrowth and will have broad relevance for the understanding of the etiology of mental health disorders.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
1R01MH096702-01
Application #
8271218
Study Section
Synapses, Cytoskeleton and Trafficking Study Section (SYN)
Program Officer
Panchision, David M
Project Start
2012-04-01
Project End
2017-03-31
Budget Start
2012-04-01
Budget End
2013-03-31
Support Year
1
Fiscal Year
2012
Total Cost
$400,000
Indirect Cost
$150,000
Name
Columbia University (N.Y.)
Department
Pathology
Type
Schools of Medicine
DUNS #
621889815
City
New York
State
NY
Country
United States
Zip Code
10032
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Batista, Andreia F R; Martínez, José C; Hengst, Ulrich (2017) Intra-axonal Synthesis of SNAP25 Is Required for the Formation of Presynaptic Terminals. Cell Rep 20:3085-3098
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Villarin, Joseph M; McCurdy, Ethan P; Martínez, José C et al. (2016) Local synthesis of dynein cofactors matches retrograde transport to acutely changing demands. Nat Commun 7:13865
Batista, Andreia Filipa Rodrigues; Hengst, Ulrich (2016) Intra-axonal protein synthesis in development and beyond. Int J Dev Neurosci 55:140-149
Baleriola, Jimena; Jean, Ying; Troy, Carol et al. (2015) Detection of Axonally Localized mRNAs in Brain Sections Using High-Resolution In Situ Hybridization. J Vis Exp :e52799
Baleriola, Jimena; Hengst, Ulrich (2015) Targeting axonal protein synthesis in neuroregeneration and degeneration. Neurotherapeutics 12:57-65
Jean, Ying Y; Baleriola, Jimena; Fà, Mauro et al. (2015) Stereotaxic Infusion of Oligomeric Amyloid-beta into the Mouse Hippocampus. J Vis Exp :e52805
Deglincerti, Alessia; Liu, Yaobin; Colak, Dilek et al. (2015) Coupled local translation and degradation regulate growth cone collapse. Nat Commun 6:6888
Baleriola, Jimena; Walker, Chandler A; Jean, Ying Y et al. (2014) Axonally synthesized ATF4 transmits a neurodegenerative signal across brain regions. Cell 158:1159-1172

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