The Mitochondrial-Derived Peptide Humanin Protects RPE Cells From Oxidative Stress, Senescence, and Mitochondrial Dysfunction.
Sreekumar. Parameswaran G PG; Ishikawa. Keijiro K; Spee. Chris C; Mehta. Hemal H HH; Wan. Junxiang J; Yen. Kelvin K; Cohen. Pinchas P; Kannan. Ram R; Hinton. David R DR
Key Findings
- Humanin is found in the cytoplasm and mitochondria of retinal cells
- Humanin reduces oxidative stress, restores mitochondrial respiration, and boosts mitochondrial DNA copy number
- Humanin prevents cell death and senescence by activating STAT3 and blocking caspaseā3
Practical Outcomes
- Humanin looks promising for protecting eye health and possibly slowing ageārelated retinal decline, but the research is limited to cell cultures. No human dosing guidelines exist yet, so biohackers should treat it as experimental and await clinical data before adding it to protocols.
Summary
The study shows that the tiny protein humanin can get inside eye cells, protect them from oxidative damage, keep their mitochondria working well, and stop them from aging or dying. This was seen in lab-grown retinal cells treated with a stress chemical, and humanin helped them stay healthy.
Abstract
To investigate the expression of humanin (HN) in human retinal pigment epithelial (hRPE) cells and its effect on oxidative stress-induced cell death, mitochondrial bioenergetics, and senescence. Humanin localization in RPE cells and polarized RPE monolayers was assessed by confocal microscopy. Human RPE cells were treated with 150 μM tert-Butyl hydroperoxide (tBH) in the absence/presence of HN (0.5-10 μg/mL) for 24 hours. Mitochondrial respiration was measured by XF96 analyzer. Retinal pigment epithelial cell death and caspase-3 activation, mitochondrial biogenesis and senescence were analyzed by TUNEL, immunoblot analysis, mitochondrial DNA copy number, SA-β-Gal staining, and p16INK4a expression and HN levels by ELISA. Oxidative stress-induced changes in transepithelial resistance were studied in RPE monolayers with and without HN cotreatment. A prominent localization of HN was found in the cytoplasmic and mitochondrial compartments of hRPE. Humanin cotreatment inhibited tBH-induced reactive oxygen species formation and significantly restored mitochondrial bioenergetics in hRPE cells. Exogenous HN was taken up by RPE and colocalized with mitochondria. The oxidative stress-induced decrease in mitochondrial bioenergetics was prevented by HN cotreatment. Humanin treatment increased mitochondrial DNA copy number and upregulated mitochondrial transcription factor A, a key biogenesis regulator protein. Humanin protected RPE cells from oxidative stress-induced cell death by STAT3 phosphorylation and inhibiting caspase-3 activation. Humanin treatment inhibited oxidant-induced senescence. Polarized RPE demonstrated elevated cellular HN and increased resistance to cell death. Humanin protected RPE cells against oxidative stress-induced cell death and restored mitochondrial function. Our data suggest a potential role for HN therapy in the prevention of retinal degeneration, including AMD.
Study Information
pubmed
2016
2016-03-01T00:00:00.000Z
10.1167/iovs.15-17053
155
69