July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Dual protective action of αA-crystallin on retinal glial and neuronal cells during metabolic stress
Author Affiliations & Notes
  • Madhu Nath
    Kellogg Eye Centre, University of Michigan, Ann Arbor, Michigan, United States
  • Yang Shan
    Kellogg Eye Centre, University of Michigan, Ann Arbor, Michigan, United States
  • Patrice E Fort
    Kellogg Eye Centre, University of Michigan, Ann Arbor, Michigan, United States
  • Footnotes
    Commercial Relationships   Madhu Nath, None; Yang Shan, None; Patrice Fort, None
  • Footnotes
    Support  R01-EY020895
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 2703. doi:
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      Madhu Nath, Yang Shan, Patrice E Fort; Dual protective action of αA-crystallin on retinal glial and neuronal cells during metabolic stress. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2703.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Diabetes initiates retinal neurodegeneration through a multitude of mechanisms implicating neuronal and non-neuronal cells. We recently demonstrated that the molecular chaperone αA-crystallin is a potent neuroprotector for retinal neurons, but the mechanism by which αA-crystallins exerts retinal neuroprotection in early diabetes is still unclear. The present study was carried out to assess the interaction between αA-crystallins and other known neuroprotective mechanisms during metabolic stress.

Methods : Differentiated R28 cells, a model of retinal neurons, as well as rMC-1, a Müller glial cell line, or primary Müller glial cells from WT and Ko-aA-crystallin mice were transfected with plasmids encoding either wild-type (WT), phosphomimetic (148D), or non phosphorylatable mutants (148A) of αA-crystallin on the 148 residue, as well as constitutively active (CA) or dominant negative (DN) forms of Akt. The cells were then either exposed to serum starvation (SS), high glucose (25mM) or high glucose with TNF-alpha (100ng/ml) (HG+T) in order to assess the effect of aA-crystallin and Akt on cell survival (cell viability assays) as well as induction of inflammation (inflammatory markers expression by qPCR).

Results : Elevated levels of inflammatory markers in SS group were diminished in αA-WT (IL-1β- 67%; MCP-1-26%; IL-6-12%) and further in αA-148D (IL-1β- 70%; MCP-1-30%; IL-6-15%) as compared to EV. The increase of IL-1β, MCP-1 & IL-6 were blunted in HG+T by αA-WT (IL-1β-17%; MCP-1-180%; IL-6-36%) and to a greater extent by αA-148D ( IL-1β-21%; MCP-1-202%; IL-6-45%) when compared to EV. The overexpression of CA-Akt in combination with αA-WT or αA-148D mutant, or by itself significantly decreased the SS-induced (αA-WT -49%; αA-148D-62%; CA-Akt alone-40%) and HG+T-induced (αA-WT -61%; αA-148D-66%; CA-Akt alone-88%) cell death compared to the EV. Of note, DN-Akt co-transfection with αA-crystallin plasmids did not show any reduction in cell death in the SS or HG+T group as compared to EV. Similarly, overexpression of aA-148A alone or in combination with Akt did not have any protective effect in either of the metabolic stress.

Conclusions : The data strongly suggest that αA-crystallin plays a dual neuroprotective role in the retina under metabolic stress, via reduction of the inflammatory response of Müller glial cells and interaction with the pro-survival Akt pathway in neurons.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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