An important goal for regenerative medicine is to understand how neurons sense and respond to axonal damage. Due to the highly polarized structure of axons, axonal transport machinery, which delivers cellular cargo from one part of the axon to the other, plays important roles in the cellular responses to injury. One major response is the induction of new axonal growth. This regenerative response requires the retrograde transport of signaling molecules from the injury site to the nucleus. Another major response is degeneration of the severed distal 'stump'. This may also rely on axonal transport machinery, since defects in the process of axonal transport usually accompany (and often proceed) axonal degeneration in neurodegenerative disorders. To study mechanisms of injury signaling, degeneration, and axonal transport, we take advantage of the powerful genetics of Drosophila as a model organism, in which we have developed a new injury paradigm that allows mechanistic characterization of injury response pathways in vivo. Our assays include nuclear reporters, which measure changes in gene expression in injured neurons, and live imaging assays that measure axonal transport of specific cargo in axons. The focus of this study is the role and mechanism of a conserved axonal kinase, named Wallenda (Wnd) in Drosophila, DLK in vertebrates. Recent studies indicate that this kinase regulates both regenerative and degenerative responses to axonal injury. Our recent observations suggest that Wnd may function by regulating the transport of specific cargo in axons. The goals of this study are to identify the Wnd-regulated cargo, and determine the role(s) of this cargo in both retrograde signaling and degeneration.

Public Health Relevance

Axonal damage triggers both regenerative and degenerative responses in neurons. We are studying a molecular pathway, which has recently been discovered to function in both the regrowth of axons after injury and also in degeneration of the part of the axon that has been severed from the cell body. The findings from this work will be important both for treatment of spinal cord injuries and also for understanding mechanisms of neurodegenerative disorders.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS069844-03
Application #
8239537
Study Section
Synapses, Cytoskeleton and Trafficking Study Section (SYN)
Program Officer
Owens, David F
Project Start
2010-04-01
Project End
2014-03-31
Budget Start
2012-04-01
Budget End
2013-03-31
Support Year
3
Fiscal Year
2012
Total Cost
$319,402
Indirect Cost
$105,027
Name
University of Michigan Ann Arbor
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Mishra, Bibhudatta; Ghannad-Rezaie, Mostafa; Li, Jiaxing et al. (2014) Using microfluidics chips for live imaging and study of injury responses in Drosophila larvae. J Vis Exp :e50998
Klinedinst, Susan; Wang, Xin; Xiong, Xin et al. (2013) Independent pathways downstream of the Wnd/DLK MAPKKK regulate synaptic structure, axonal transport, and injury signaling. J Neurosci 33:12764-78
Wang, Xin; Kim, Jung Hwan; Bazzi, Mouna et al. (2013) Bimodal control of dendritic and axonal growth by the dual leucine zipper kinase pathway. PLoS Biol 11:e1001572
Wang, Adrienne M; Miyata, Yoshinari; Klinedinst, Susan et al. (2013) Activation of Hsp70 reduces neurotoxicity by promoting polyglutamine protein degradation. Nat Chem Biol 9:112-8
Frank, C Andrew; Wang, Xinnan; Collins, Catherine A et al. (2013) New approaches for studying synaptic development, function, and plasticity using Drosophila as a model system. J Neurosci 33:17560-8
Xiong, Xin; Collins, Catherine A (2012) A conditioning lesion protects axons from degeneration via the Wallenda/DLK MAP kinase signaling cascade. J Neurosci 32:610-5
Ghannad-Rezaie, Mostafa; Wang, Xing; Mishra, Bibhudatta et al. (2012) Microfluidic chips for in vivo imaging of cellular responses to neural injury in Drosophila larvae. PLoS One 7:e29869
Xiong, Xin; Wang, Xin; Ewanek, Ronny et al. (2010) Protein turnover of the Wallenda/DLK kinase regulates a retrograde response to axonal injury. J Cell Biol 191:211-23