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XINYUE ZHU, Xueting Pei, Zhenya Gao, Yiwen Li, Rong Wen; Induction of Erk phosphorylation by MANF in retinal Müller cells. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2495. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
MANF (Mesencephalic astrocyte-derived neurotrophic factor) is a potent neurotrophic factor for photoreceptors and retinal ganglion cells. But the mechanism underlying its neuroprotective effects is not well understood. We found that MANF induces Erk phosphorylation in the retina, suggests the involvement of the Erk MAPK pathway.
Recombinant human MANF was expressed in E. coli and purified. To investigate phosphorylated Erk (p-Erk) in the retina, the left eyes of Sprague-Dawley rats were injected intravitreally with MANF (10 µg in 3 µl), and the right eyes were injected with 3 µl PBS (phosphate buffered saline) as controls. Retinas were collected at given time points after injection. Müller cells were isolated from rat retina and cultured in DMEM + 10% fetal bovine serum. Cells were treated with MANF (100 ng/ml) and collected at given time points after addition of MANF. The levels of p-Erk were assessed by Western blot analysis. Immunocytochemical analysis was employed to localize the MANF-induced p-Erk.
A dramatic increase in p-Erk was detected 30 min after MANF injection into the vitreous, and the increase lasted for up to 8 hours. Immunostaining for p-Erk detected a group of positive cells in the inner nuclear layer, suggesting that they are Müller cells. The MANF-induced p-Erk is confirmed in cultured Müller cells. Addition of MANF (100 ng/ml) to culture medium induced a significant increases in p-Erk as soon as 5 min. The increase in p-Erk reached a peak at 15 min after treatment and declined to normal level by 30 min.
These data strongly suggest that the Erk MAPK pathway is involved in mediating extracellular neurotrophic activity of MANF. Experiments with cultured Müller cells provide evidence that MANF directly interaction with Müller cells.
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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