MINI REVIEW article
Front. Cell Dev. Biol.
Sec. Membrane Traffic and Organelle Dynamics
Volume 13 - 2025 | doi: 10.3389/fcell.2025.1593840
This article is part of the Research TopicBiology of Lysosome-Related OrganellesView all 8 articles
Specialised features of melanosomes in health and disease in the retinal pigment epithelium
Provisionally accepted
- Institute of Ophthalmology, Faculty of Brain Sciences, University College London, London, England, United Kingdom
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This mini-review focuses on melanosome biogenesis, positioning and function in the retinal pigment epithelium (RPE) where melanosomes absorb light scatter and protect against the harmful effects of photo-oxidation. RPE melanosomes share a common biogenesis pathway with those of skin melanocytes but are made primarily embryonically and are retained by the RPE throughout life. They do however move from the cell body into the apical processes which, in mammalian RPE, is regulated by a machinery related to that regulating melanosome distribution in skin melanocytes. Melanosomes in the RPE make extensive membrane contacts with the ER and mitochondria although their role in adult RPE remains to be fully established. Albinism is associated with multiple visual defects and reduced or absent pigmentation in melanosomes has implications for long term visual health. Age-related changes in melanosomes have been implicated in retinal degenerative disease, including age-related macular disease (AMD). The lysosomes of the RPE have an unparalleled degradative burden arising from the daily phagocytosis of the distal tips of photoreceptor outer segments, which is part of a daily process of outer segment renewal. A failure to fully process the phagocytosed outer segments leads to a build-up of the toxic ageing pigment, lipofuscin, which accumulates in all ageing RPE. Melanolipofuscin also accumulates in the RPE with age and may result from melanin-mediated degradation of lipofuscin through melanin chemiexcitation. Age-related loss of melanosome-mediated protection could be an important component of age-related visual decline.
Keywords: Retinal pigment epithelium 1, melanosome 2, albinism 3, age-related macular degeneration 4, melanolipofuscin 5
Received: 14 Mar 2025; Accepted: 08 Aug 2025.
Copyright: © 2025 Doncheva, Eden and Futter. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Clare E Futter, Institute of Ophthalmology, Faculty of Brain Sciences, University College London, London, EC1V 9EL, England, United Kingdom
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