Tooth enamel in the retina
Age-related retinal degeneration was associated with tooth enamel protein
Sergey Vasiliev, Naked Science
Impaired vision and blindness in the elderly are most often associated with age-related destruction of the retina (macular degeneration), which is usually caused by blood supply disorders. In most cases, this is the so-called dry macular degeneration with the formation and accumulation of a characteristic mineralized plaque that gradually destroys photoreceptors. It often ends with degradation of the central field of vision, partial and complete blindness.
Recently, scientists from the American National Eye Institute (NEI) discovered that the protein amelotin is involved in the formation of this plaque. To understand their surprise, it is worth remembering that amelotin is a calcium–binding protein that forms the matrix of tooth enamel, where it is produced by epithelial tissue cells - ameloblasts (adamantoblasts). The article by Graeme Wistow and his colleagues was published in the journal Translational Research (Rajapakse et al., Amelotin is expressed in retinal pigment epithelium and localizes to hydroxyapatite deposits in dry age-related macular degeneration). Briefly about their work is described in the message of the NEI press service.
Deposits of dry macular degeneration are formed by the calcium-containing mineral hydroxyapatite, which accumulates under the retinal epithelium. The epithelium provides a supply of light-sensitive receptors, but deposits block the normal movement of blood through it. Scientists repeated this process in vitro, "in vitro", by growing retinal epithelial cells and subjecting them to stress (nutrient deficiency).
Above: hydroxyapatite balls (pink) and amelotin protein (green) in the Bruch membrane – the innermost layer of the vascular membrane of the eye with dry macular degeneration. Below: deposits of cholesterol, lipids, proteins and minerals under the retinal pigment epithelium; the image was obtained using optical coherence tomography – VM.
After a few days of such exposure, the AMTN gene encoding amelotin was activated in the cells, then the accumulation of minerals began. Interested in this, the scientists repeated experiments with cells in which the AMTN was blocked. Indeed, no mineralization was observed in this case, which indicates the key role played by amelotin in the process.
These conclusions were confirmed by the analysis of sediment samples taken from patients suffering from dry macular degeneration. According to scientists, the participation of amelotin should be understood in more detail: perhaps this mechanism will become the target for new types of treatment of age-related vision degradation.
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