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Priscilla Sayami Akamine, Carolina B Del Debbio, Raquel Cecília Teles Rodrigues, Cesar Seigi Fuziwara, Edna Teruko Kimura, Dania E Hamassaki; Müller glial cells modulate the expression of vitreous matrix components. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):417.
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© ARVO (1962-2015); The Authors (2016-present)
Vitreous remodeling occurs from an early stage and continues through the normal aging when the vitreous undergoes structural changes such as the gradual lamellae formation and liquefied spaces, which eventually leads to posterior vitreous detachment. We have previously shown that the let-7 family of microRNAs is upregulated with aging in the vitreous and retina of Wistar rats, and that Müller glial cells may play an important role in the production and release of microRNAs into the vitreous via extracellular vesicles. Considering that some of the vitreous components are possible targets of let-7 microRNAs and that the ciliary epithelium (CE) is one of main vitreous source, our aim was to investigate: 1) the expression of hyaluronan synthase, types II, V and IX collagens by the CE cells and their potential modulation by Müller glial cells; 2) expression of let-7 microRNAs by the CE explants.
Newborn (n=6) and adult Wistar rats (n=6) were sacrificed by anesthesia overdose, their eyes were enucleated and retinas and CE collected. A primary culture of rat enriched Müller glia was performed and the conditioned medium was collected after 4 days. Adult rat CE explants were cultured with and without the Müller glia conditioned medium, and after 3 days the explants were dissected out to separate the outer from the inner epithelium. Samples were then processed and analyzed for collagen type II, V, IX, hyaluronan synthase and let-7 microRNAs gene expression by PCR.
The investigated vitreous matrix components were expressed by newborn and adult CE cells. Type V collagen showed a higher expression in the ciliary inner epithelium (2.5 times) compared to the outer epithelium. Under treatment of CE cells with the Müller conditioned medium, the collagen type V expression was negatively modulated in the inner epithelium, and positively in the outer one. The expression of let-7 (let-7a,-b,-c,-d,-e,-f,-g,-i) microRNAs were detected in CE explants and Müller glial cells.
The expression of collagens II, V and IX as well as hyaluronan synthase suggests the importance of the CE, especially the inner epithelium, in the biosynthesis of vitreous matrix components. The let-7 microRNAs expression and the changes observed in collagen type V expression, a target of let-7, suggest that Müller glial cells may play an important role in releasing factors, as microRNAs, to modulate vitreous components.
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