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Kevin Toolan, Mercy Pawar, Taichi Suzuki, Cagri G Besirli; ER-stress and mesencephalic astrocyte-derived neurotrophic factor (MANF) in an in vitro model of photoreceptors. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4614.
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© ARVO (1962-2015); The Authors (2016-present)
We recently identified MANF as a potential neuroprotective factor in the subretinal fluid of pediatric patients with retinal detachment. MANF has been implicated in ER-stress response for other models. This study examined the signaling pathways activated by ER stress and the expression of novel neurotrophic factor MANF in photoreceptors.
Proteomic profiling of subretinal fluid samples from patients with retinal detachment was performed. Retina- retinal pigment epithelium (RPE) separation was created in rats by subretinal injection of 1% hyaluronic acid for. MANF was injected into the subretinal space at the time of separation. Retinas were harvested for western blot analysis 3 days after separation. Eyes were enucleated after 3 days for TUNEL & immunocytochemistry and 2 months for long term effect. Cultured 661W photoreceptor cells were subjected to Tunicamycin to induce ER stress and analyzed by western blot.
Proteomic profiling revealed a selective increase in MANF in the subretinal fluid of pediatric patients with retinal detachment as compared to adult patients. Western blot analysis showed no significant change in the level of MANF expression in the retina after retina-RPE separation in the adult rat. 661w cells treated with 1ug/ml of Tunicamycin demonstrated an upregulation of MANF with secretion into the cell media at 24hours. Both binding immunoglobulin protein (BIP), a UPR response protein, and Inositol-requiring enzyme 1 (IRE1a) demonstrated increased expression after Tunicamycin exposure.
MANF was identified in the subretinal fluid collected from pediatric patients with retinal detachment, suggesting a potential role in photoreceptor neuroprotection.ER stress in 661W photoreceptor cells led to increased BIP and IRE1a, followed by MANF secretion. Our results indicate that ER stress and MANF response may be one of the signaling pathways activated during retinal detachment.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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