Our long-term goal is to prevent neuronal loss and functional deficits in retinal ischemia. Pursuant to our objective, we have identified a new, scantily explored membrane channel protein pannexin1 (Panx1), as a promising source for discovering new therapies. We established that Panx1 function as a molecular mediator of ischemic neuronal injury, and genetic ablation of this channel protects retinal ganglion cells from ischemic damage. Our central hypothesis states that Panx1 serves as a critical """"""""convergence hub"""""""" for external stressors. Our proposed studies will compare relative contribution of distinct toxicity mechanisms mediated by Panx1 and identify which stimuli or their combinations trigger pathological opening of this channel in vulnerable retinal ganglion cells in ischemia.
Specific Aims are designed to: 1) analyze toxicity pathways triggered by the Panx1 channel opening for their relative contribution toxicity to RGC injury~ 2) Compare protective effects of partial inhibition vs. full blockade or ablation of Panx1 channel in vivo in experimental retinal ischemia-reperfusion model. We will focus on both neuronal survival and preservation of retinal functionality following ischemia. Significance. Protecting retinal neurons from ischemic injury is essential for a comprehensive therapeutic strategy. The understanding of the Panx1-mediated toxicity pathways and their contribution to neuronal injury will permanently alter both conceptual and therapeutic approaches to retinal and brain ischemia. We will use the expertise developed and the unique tools designed for this proposal to evaluate the feasibility of Panx1 blockade for suppressing or preventing the vision loss in transient ischemia, an important clinical problem and the NIH NEI research objective.

Public Health Relevance

Our long-term goal is to prevent neuronal loss and functional deficits in retinal ischemia. We have identified a new, previously unexplored molecular mediator of ischemic neuronal injury, a channel protein pannexin1 (Panx1). Based on our main finding demonstrating that the Panx1 gene ablation suppresses neuronal loss in ischemia-reperfusion, we hypothesize that in ischemia Panx1 function as a molecular mediator of neuronal injury. Our central hypothesis states that Panx1, through opening of a large membrane pore, facilitates ischemic injury and oxidative stress to the retina. We seek to reveal cause-and-effect relationship between Panx1 and the activation of distict toxicity pathways in ischemia. We have developed a unique Panx1 conditional knockout mouse and novel Panx1-specific patch clamp protocol to reach the objectives of this proposal. The major outcomes of this study include the new knowledge on the Panx1-mediated toxicity pathways and their contribution to neuronal injury. We will also test a therapeutic potential of Panx1 blockade in alleviating retinal ischemic injury using animal model of ischemia-reperfusion. PHS 398/2590 (Rev. 09/04, Reissued 4/2006) Page Continuation Format Page

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY021517-03
Application #
8634099
Study Section
Special Emphasis Panel (ZRG1-BDPE-N (09))
Program Officer
Chin, Hemin R
Project Start
2012-04-01
Project End
2015-03-31
Budget Start
2014-04-01
Budget End
2015-03-31
Support Year
3
Fiscal Year
2014
Total Cost
$374,850
Indirect Cost
$129,850
Name
University of Miami School of Medicine
Department
Ophthalmology
Type
Schools of Medicine
DUNS #
052780918
City
Coral Gables
State
FL
Country
United States
Zip Code
33146
Wicki-Stordeur, Leigh E; Sanchez-Arias, Juan C; Dhaliwal, Jagroop et al. (2016) Pannexin 1 Differentially Affects Neural Precursor Cell Maintenance in the Ventricular Zone and Peri-Infarct Cortex. J Neurosci 36:1203-10
Mac Nair, Caitlin E; Schlamp, Cassandra L; Montgomery, Angela D et al. (2016) Retinal glial responses to optic nerve crush are attenuated in Bax-deficient mice and modulated by purinergic signaling pathways. J Neuroinflammation 13:93
Vanden Berghe, Tom; Hulpiau, Paco; Martens, Liesbet et al. (2015) Passenger Mutations Confound Interpretation of All Genetically Modified Congenic Mice. Immunity 43:200-9
Tordoff, Michael G; Aleman, Tiffany R; Ellis, Hillary T et al. (2015) Normal Taste Acceptance and Preference of PANX1 Knockout Mice. Chem Senses 40:453-9
Gaynullina, Dina; Tarasova, Olga S; Kiryukhina, Oxana O et al. (2014) Endothelial function is impaired in conduit arteries of pannexin1 knockout mice. Biol Direct 9:8
Makarenkova, Helen P; Shestopalov, Valery I (2014) The role of pannexin hemichannels in inflammation and regeneration. Front Physiol 5:63
Pronin, Alexey; Levay, Konstantin; Velmeshev, Dmitry et al. (2014) Expression of olfactory signaling genes in the eye. PLoS One 9:e96435
Beckel, Jonathan M; Argall, Arthur J; Lim, Jason C et al. (2014) Mechanosensitive release of adenosine 5'-triphosphate through pannexin channels and mechanosensitive upregulation of pannexin channels in optic nerve head astrocytes: a mechanism for purinergic involvement in chronic strain. Glia 62:1486-501
Shestopalov, Valery I; Slepak, Vladlen Z (2014) Molecular pathways of pannexin1-mediated neurotoxicity. Front Physiol 5:23
Krizaj, David; Ryskamp, Daniel A; Tian, Ning et al. (2014) From mechanosensitivity to inflammatory responses: new players in the pathology of glaucoma. Curr Eye Res 39:105-19

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