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Abstract #48670 Published in IGR 14-1
Involvement of EphB/Ephrin-B signaling in axonal survival in mouse experimental glaucoma
Fu CT; Sretavan DInvestigative Ophthalmology and Visual Science 2012; 53: 76-84
PURPOSE: To examine the functional significance of EphB/ephrin-B upregulation in mouse experimental glaucoma. METHODS: In a loss-of-function approach, mouse mutants lacking EphB2 (EphB2(-/-)) or EphB3 (EphB3(-/-)) protein, and mutants expressing EphB2 truncated in the C-terminus (EphB2(lacZ/lacZ)) were subjected to laser-induced ocular hypertension (LIOH), an experimental mouse model of glaucoma. The number of optic nerve axons was counted in paraphenylenediamine (PPD)-stained sections and compared between EphB mutants and wild type littermates. In a gain-of-function approach, retina/optic nerve explants obtained from LIOH-treated animals were exposed to EphB2-Fc recombinant proteins or Fc control proteins. Tissue sections through the optic nerve head (ONH) were labeled with neuron-specific anti-tubulin β-III antibody to determine axonal integrity. RESULTS: Both EphB2 and EphB3 null mutant mice exhibited more severe axonal degeneration than wild type littermates after treatment with LIOH. Mutant mice in which the C-terminal portion of EphB2 is truncated had an intermediate phenotype. Application of EphB2-Fc recombinant protein to LIOH-treated optic nerve explants resulted in greater sparing of tubulin β-III-containing retinal ganglion cell (RGC) axons. CONCLUSIONS: These results provide genetic evidence in mice that both EphB/ephrin-B forward and reverse signaling feed into an endogenous pathway to moderate the effects of glaucomatous insult on RGC axons. LIOH-induced axon loss is maintained in retina/optic nerve explants after removal from an ocular hypertensive environment. Exogenous application of EphB2 protein enhances RGC axon survival in explants, suggesting that modulation of Eph/ephrin signaling may be of therapeutic interest.
Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA.
Full articleClassification:
5.1 Rodent (Part of: 5 Experimental glaucoma; animal models)
3.6 Cellular biology (Part of: 3 Laboratory methods)
2.15 Optic nerve (Part of: 2 Anatomical structures in glaucoma)
