June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
The mitochondrial-derived peptide humanin improves mitochondrial bioenergetics after endoplasmic reticulum stress in human RPE cells
Author Affiliations & Notes
  • Hiroto Terasaki
    Doheny Eye Institute, Los Angeles, California, United States
    Ophthalmology, Kagoshima University, Kagoshima, Japan
  • Parameswaran G Sreekumar
    Doheny Eye Institute, Los Angeles, California, United States
  • Hemal H Mehta
    USC Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, United States
  • Pinchas Cohen
    USC Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, United States
  • David R Hinton
    Ophthalmology, University of Southern California, Los Angeles, California, United States
    Pathology, University of Southern California, Los Angeles, California, United States
  • Ram Kannan
    Doheny Eye Institute, Los Angeles, California, United States
  • Footnotes
    Commercial Relationships   Hiroto Terasaki, None; Parameswaran Sreekumar, None; Hemal Mehta, None; Pinchas Cohen, CohBar,Inc. (I), CohBar,Inc. (C); David Hinton, None; Ram Kannan, None
  • Footnotes
    Support  EY0154, the Arnold and Mabel Beckman Foundation, 1R01AG 034430, 1P01AG034906
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 5361. doi:
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      Hiroto Terasaki, Parameswaran G Sreekumar, Hemal H Mehta, Pinchas Cohen, David R Hinton, Ram Kannan; The mitochondrial-derived peptide humanin improves mitochondrial bioenergetics after endoplasmic reticulum stress in human RPE cells. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5361.

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

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Abstract

Purpose : We have recently reported that the mitochondrial-derived peptide humanin (HN) protected human retinal pigment epithelial cells (hRPE) from endoplasmic reticulum (ER)-induced stress by a mechanism that involved ER-mitochondrial crosstalk and selective increase in mitochondrial glutathione (Matsunaga et al. PLoS ONE 11(10): e0165150, 2016). The aim of the present work was to study the effect of ER stress on mitochondrial bioenergetics in hRPE cells and to determine the effect of HN on ER-induced changes on key mitochondrial parameters.

Methods : Early passage primary cultured hRPE cells were treated with tunicamycin (TM, 3 µg/ml or 10 µg/ml) for 12 h with or without the co-treatment of HN (10 µg/ml or 20 µg/ml). Mitochondrial respiration parameters (oxygen consumption rate (OCR) and ATP production, expressed as pmol/min/total DNA) were analyzed by a Seahorse XF96 Analyzer. In separate experiments, TM-induced changes as well as the effect of HN co-treatment on ER stress biomarker GRP78 (Western blot) and apoptotic cell death (TUNEL) were measured.

Results : TM caused a significant two fold increase in GRP78 expression over the untreated hRPE controls. HN co-treatment resulted in a decrease in GRP78 as compared to TM-treated cells; however, GRP78 expression remained higher than in untreated controls. TM caused 12.7 % cell death from apoptosis with 10 µg/ml TM treatment (TUNEL) which was significantly inhibited to 5.1% and 3.9% by co-treatment with HN (10 µg/ml and 20 µg/ml respectively). Both OCR and ATP production by hRPE cells were significantly decreased with 3 µg/ml TM treatment (52.1% and 63.7% respectively; p<0.01 vs untreated controls). HN co-treatment with 10 µg/ml or 20 µg/ml elevated OCR over TM group by 42.0% and 43.2% respectively. ATP production rates were also increased over the corresponding rates with TM treatment. However, the restoration of OCR and ATP production was partial as compared to untreated controls or hRPE cells treated with HN alone.

Conclusions : Our results show for the first time that ER stress significantly inhibits mitochondrial respiration in RPE cells. HN partially protects RPE from ER stress-induced attenuation of mitochondrial function and represents a novel therapeutic approach for ER-related retinal diseases.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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