Exosomes and alpha-synuclein within retina fromautophagy to protein spreading in neurodegeneration

1 March 2022

Archives Italiennes de Biologie – A Journal of Neuroscience – 2021

In this article, evidence is presented for the specific presence of α-synuclein in various retinal layers. The topographic model used in the study suggests the presence of an apparatus that can spread α-synuclein throughout the retina. This may occur because of the beneficial effects of α-synuclein protein in maintaining synaptic activity and cell proliferation. However, the autophagy process may be affected in the presence of retinal degeneration. Because the process of autophagy is known to be impaired in AMD and other types of retinal degeneration, it is likely that the widespread accumulation of α-synuclein observed in the later stages of all forms of retinal degeneration may be due to this clearance pathway becoming congested. When nonspecific retinal degeneration occurs, multilayer aggregation of α-synuclein is observed. Intriguingly, a potential role of melanin under the effects of light and the stimulatory activity of the sympathetic nervous system has been postulated. The significance of these findings extends beyond the retinal layers since retinal degeneration and the role of α-synuclein and that of innervation by tyrosine hydroxylase-positive fibres are similarly described for neurodegenerative disorders affecting the central nervous system. These results support further investigation into the role of light in melanin production and function, depending on the specific wavelength and on the stimulation of endogenous stem cells positioned at the retinal periphery, within an area extending from the ora serrata towards the margin of the ciliary body.