A major barrier to regeneration of CNS axons is the presence of growth-inhibitory proteins associated with myelin debris and the glial scar. Functional recovery after CNS injury requires that this inhibition be overcome. Recent studies suggest that changes in cAMP, along with increases in PKC, EGFR, and RhoA activities, are important aspects of inhibitory signaling. However, we still lack knowledge about the number/identity of inhibitory proteins associated with inhibition at injury sites, the detailed signaling mechanisms employed by inhibitory receptors, and the cell type-specific responses of damaged axons. Further, there are problems associated with current pharmacological strategies, including lack of specificity, uncertain toxicities, and the targeting of pathways with pleiotrophic functions. To overcome these difficulties, we have initiated a phenotype-based unbiased screen of a novel chemical compound library chosen for its favorable chemical properties rather than known biological function. The screen is based on the ability of compounds to increase neurite outgrowth from CNS neurons challenged with inhibitory myelin substrates. Initial results have produced 4 """"""""hit compounds"""""""" capable of strongly increasing neurite growth. Subsequent investigations indicate that the hit compounds a) act on different neuronal types, b) selectively overcome inhibition rather than promote growth, c) are highly potent, d) overcome inhibition in distinct assays relevant to injury, e) do not affect cAMP levels, PKC activity, or EGFR activation, f) alter microtubule dynamics, and g) promote regeneration in vivo. Because the compounds are potent and selective, and may act through novel mechanisms, they are exciting candidates for therapeutic development and for mechanistic studies of regeneration inhibition. The proposal is to 1) investigate the signaling mechanisms and protein targets of the 4 hit compounds, 2) examine the ability of 1 hit compound to promote regeneration after spinal cord injury or optic nerve crush in vivo, and 3) screen the full 4000 compound library on a novel inhibitory (proteoglycan) substrate. These experiments could provide key insights into regeneration inhibition, and pave the way for a novel approach to CNS injury.
The proposed experiments will investigate the mechanisms of action of novel compounds promoting regeneration, and elucidate their ability to increase axonal regrowth after CNS injury.
|Ruschel, Jörg; Hellal, Farida; Flynn, Kevin C et al. (2015) Axonal regeneration. Systemic administration of epothilone B promotes axon regeneration after spinal cord injury. Science 348:347-52|
|Lerch, Jessica K; Martínez-Ondaro, Yania R; Bixby, John L et al. (2014) cJun promotes CNS axon growth. Mol Cell Neurosci 59:97-105|
|Al-Ali, Hassan; Schürer, Stephan C; Lemmon, Vance P et al. (2013) Chemical interrogation of the neuronal kinome using a primary cell-based screening assay. ACS Chem Biol 8:1027-36|
|Gatto, Graziana; Dudanova, Irina; Suetterlin, Philipp et al. (2013) Protein tyrosine phosphatase receptor type O inhibits trigeminal axon growth and branching by repressing TrkB and Ret signaling. J Neurosci 33:5399-410|
|Lerch, Jessica K; Kuo, Frank; Motti, Dario et al. (2012) Isoform diversity and regulation in peripheral and central neurons revealed through RNA-Seq. PLoS One 7:e30417|
|Blackmore, Murray G; Wang, Zimei; Lerch, Jessica K et al. (2012) Kruppel-like Factor 7 engineered for transcriptional activation promotes axon regeneration in the adult corticospinal tract. Proc Natl Acad Sci U S A 109:7517-22|
|Nelersa, Claudiu M; Barreras, Henry; Runko, Erik et al. (2012) High-content analysis of proapoptotic EphA4 dependence receptor functions using small-molecule libraries. J Biomol Screen 17:785-95|
|Lerch, Jessica K; Bixby, John L; Lemmon, Vance P (2012) Isoform diversity and its importance for axon regeneration. Neuropathology 32:420-31|
|Motti, Dario; Bixby, John L; Lemmon, Vance P (2012) MicroRNAs and neuronal development. Semin Fetal Neonatal Med 17:347-52|
|Slepak, Tatiana I; Salay, Lindsey D; Lemmon, Vance P et al. (2012) Dyrk kinases regulate phosphorylation of doublecortin, cytoskeletal organization, and neuronal morphology. Cytoskeleton (Hoboken) 69:514-27|
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