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Fanfei Liu, Lawrence J Rizzolo; Pleiotropic effects of claudin-19 on RPE gene expression include autophagy. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1665.
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© ARVO (1962-2015); The Authors (2016-present)
Earlier studies in our laboratory implicated the tight junction protein, claudin-19, in the regulation of genes for a variety of RPE functions. In exploring the mechanisms that might be involved, we discovered that genes related to autophagy and perhaps phagocytosis were involved.
The expression of claudin-19 in human stem cell-derived RPE was knocked down using a cocktail of siRNAs. As a control, we used siRNAs directed against claudin-4, which is not expressed by RPE. Expression was monitored by immunoblotting and real-time RT-PCR.
The siRNAs directed against claudin-19 mRNA reduced the transepithelial electrical resistance, the amount of mRNA message, and the amount of claudin-19 protein. PCR experiments revealed that a variety of mRNAs for proteins related to autophagy were down-regulated. These proteins were involved early, mid, and late stages of the autophagy pathway from the formation of phagophores (UVRAG, ULK1, BCL2, Beclin, ATG7, ATG12, and ATG14) to the formation of autophagosomes (LC3 and SQSTM1). Immunoblotting confirmed that LC3-I, LC3-II, and SQSTM1 were decreased relative to controls.
Autophagy and phagocytosis are among the several key RPE functions that are regulated directly or indirectly by Claudin-19.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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