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Parameswaran G Sreekumar, Hiroto Terasaki, Christine Spee, Hemal H Mehta, Junxiang Wan, Kelvin Yen, Pinchas Cohen, Ram Kannan, David R Hinton; Humanin enhances mitochondrial biogenesis in RPE cells. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5016. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Mitochondria are central to energy metabolism and apoptosis, and mitochondrial dysfunction is a hallmark of aging and age-related diseases such as age-related macular degeneration. Humanin (HN) is transcribed from an open reading frame within the mitochondrial 16S ribosomal RNA. HN is a multipotent peptide with cytoprotective, metabolic, anti-fibrilogenic and anti-inflammatory properties. The present study tested the hypothesis that exogenous administration of HN could inhibit oxidative stress-induced cell death in RPE cultures, by improving mitochondrial function and biogenesis.
Primary hRPE cells were treated with 150 µM tert-Butyl hydroperoxide (tBH) in the absence/presence of 10 µg HN for 24 h. Mitochondrial bioenergetics was measured in RPE cells using the XF96 analyzer. Mitochondrial biogenesis was studied by measuring mitochondrial DNA copy number by PCR, determining mitochondrial number by transmission electron microscopy (TEM) and evaluating levels of mitochondrial transcription factor A (mtTFA), a biogenesis regulating protein, by Western blot.
Primary hRPE cells treated with 150 µM tBH for 24 h showed a significant decrease in basal respiration and ATP turnover while HN co-treatment significantly restored mitochondrial bioenergetics. There was a significant increase in mtDNA copy number in RPE cells co-treated with HN plus tBH when compared to cells treated with tBH alone. TEM studies showed a significant increase in the mitochondria number in cells co-treated with HN plus tBH over tBH-only treated cells. We also found a significant increase in the protein level of mtTFA in HN only and HN plus tBH treated cells over tBH-only treated cells.
Collectively, our data strongly support the contention that HN protects RPE cells from oxidant injury by enhancing mitochondrial bioenergetics and biogenesis. Thus, HN should be further studied as a therapeutic peptide in improving tissue function in conditions characterized by mitochondrial dysfunction.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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