March 19, 2021
Keio University School of Medicine
A research group led by Professor Kazuo Tsubota, Project Associate Professor Yoko Ozawa (concurrently a Research Professor at St. Luke's International University), and Project Assistant Professor Kohei Homma of the Department of Ophthalmology, along with Professor Hideyuki Okano of the Department of Physiology, all from the Keio University School of Medicine, has discovered that taurine, an amino acid, maintains cell proliferation and survival and suppresses retinal degeneration by preventing increased oxidative stress. This finding was made in a study using induced pluripotent stem cells (iPS cells) derived from patients with a mitochondrial gene mutation that causes retinal degeneration.
Mitochondria are intracellular organelles important for energy metabolism and other functions. Mitochondrial abnormalities are implicated in the pathogenic mechanisms of not only retinitis pigmentosa but also many diseases associated with aging, such as age-related macular degeneration. However, a treatment for these conditions has yet to be established.
This study used iPS cells derived from somatic cells of patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), a disease that causes mitochondrial dysfunction and degeneration of the retina, muscles, and nerve tissues due to a mitochondrial gene mutation (MELAS-iPS cells). It also used retinal pigment epithelium (RPE) created by differentiating these cells into three-dimensional retinal tissue (organoids). A comprehensive analysis of metabolites revealed that MELAS-iPS cells exhibit an imbalance in energy metabolism and increased oxidative stress. Furthermore, when MELAS-iPS cells were differentiated into RPE, a component of the eye's retina, they were shown to degenerate by losing their original epithelial properties and undergoing epithelial-mesenchymal transition (EMT) due to increased oxidative stress. This study has now clarified that taurine can suppress both of these processes.
The results of this study suggest that taurine may be effective in treating retinal degeneration caused by mitochondrial dysfunction. Based on these findings, it is hoped that new preventive and therapeutic methods will be developed for blinding diseases that currently have no cure.
This research was published in the online edition of "Redox Biology" on March 8, 2021 (UK time).
Please see below for the full press release.