The failure of axon regeneration in the central nervous system (CNS) prevents treatment of a wide range of CNS afflictions, including spinal cord injury, stroke, and diseases like Parkinson's. One major reason that regeneration fails is that many CNS undergo a developmental loss in their intrinsic capacity for axon growth. To restore function after CNS injury or disease it is essential that we devise means to enhance the intrinsic growth state of CNS neurons. We recently identified the Krppel-like family of transcription factors (KLFs) as key regulators of intrinsic regenerative capacity in CNS neurons. Critically, a transcriptionally active mutant, VP16-KLF7, promotes axon regeneration by injured corticospinal tract (CST) neurons, an important therapeutic target. Robust regenerative responses were achieved using viral delivery to adult wild-type animals, raising potential clinical relevance for this novel pro-regenerative tool. To further explore the potential of KLF7 activity t promote CNS regeneration, three key questions must be addressed, corresponding to our aims. First because recovery from SCI depends on multiple functional modalities carried by diverse fiber tracts, we will use viral-mediated gene delivery to test the ability of VP16-KLF7 to promote regeneration in additional neuronal populations. Targeting additional neuronal subtypes has the potential to broaden the range of behavioral improvement after SCI. Second, we will examine the expression of pro-regenerative genes in neurons stimulated by VP16-KLF7 in order to determine the potential relationship between with known pro-regenerative (e.g. mTOR, CNTF) or anti-regenerative (e.g. chondroitin sulfate proteoglycan (CSPG)) pathways and signals. Based on this information we will rationally combine VP16/KLF7 with viral particles that target complementary pathways, potentially inducing additive or synergistic improvements in axon regeneration. Finally, we will examine the extent to which KLF7-stimulated axons succeed in forming functional synapses on appropriate target cells and ultimately contribute to functional recovery. Using viral gene delivery we will co-express VP16- KLF7 with optogenetic constructs that enable the treated neurons to be reversibly activated or silenced. This technique will allow us to determine the specific contribution of the treated neurons to electrophysiological and behavioral output as regeneration proceeds. Taken together, these experiments have a strong potential to extend the use of a promising new pro-regenerative tool and lead to the development of novel combinatorial methods to promote axon regeneration and functional recovery in the injured CNS, leading to novel treatment options for people suffering from CNS afflictions.

Public Health Relevance

A major challenge to treating injuries to the brain and spinal cord is that once severed, the axonal processes that carry information in the nervous system are unable to regrow. Using a rodent model of spinal cord injury we are testing a new gene therapy approach to restore connection and function across the injury site.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS083983-03
Application #
8847417
Study Section
Clinical Neuroplasticity and Neurotransmitters Study Section (CNNT)
Program Officer
Jakeman, Lyn B
Project Start
2013-07-15
Project End
2016-05-31
Budget Start
2015-06-01
Budget End
2016-05-31
Support Year
3
Fiscal Year
2015
Total Cost
Indirect Cost
Name
Marquette University
Department
Other Basic Sciences
Type
Sch Allied Health Professions
DUNS #
046929621
City
Milwaukee
State
WI
Country
United States
Zip Code
53201
Venkatesh, Ishwariya; Mehra, Vatsal; Wang, Zimei et al. (2018) Developmental Chromatin Restriction of Pro-Growth Gene Networks Acts as an Epigenetic Barrier to Axon Regeneration in Cortical Neurons. Dev Neurobiol 78:960-977
Venkatesh, Ishwariya; Blackmore, Murray G (2017) Selecting optimal combinations of transcription factors to promote axon regeneration: Why mechanisms matter. Neurosci Lett 652:64-73
Wang, Zimei; Winsor, Kristen; Nienhaus, Christopher et al. (2017) Combined chondroitinase and KLF7 expression reduce net retraction of sensory and CST axons from sites of spinal injury. Neurobiol Dis 99:24-35
Jayaprakash, Naveen; Wang, Zimei; Hoeynck, Brian et al. (2016) Optogenetic Interrogation of Functional Synapse Formation by Corticospinal Tract Axons in the Injured Spinal Cord. J Neurosci 36:5877-90
Wang, Zimei; Reynolds, Ashley; Kirry, Adam et al. (2015) Overexpression of Sox11 promotes corticospinal tract regeneration after spinal injury while interfering with functional recovery. J Neurosci 35:3139-45
Simpson, Matthew T; Venkatesh, Ishwariya; Callif, Ben L et al. (2015) The tumor suppressor HHEX inhibits axon growth when prematurely expressed in developing central nervous system neurons. Mol Cell Neurosci 68:272-83