
Background and PurposeVision depends on retinoid exchange between the retinal pigment epithelium (RPE) and photoreceptors. Defects in any step of the canonical visual cycle can lead to retinal degenerations. All‐trans‐retinol (atROL) plays an important role in visual signal transduction. However, howatROLenters humanRPEfrom the apical membrane remains unclear. This study investigated the role of human organic anion transporting polypeptide 1A2 (OATP1A2) inatROLuptake in humanRPE.Experimental ApproachImmunoblotting and immunostaining elucidated the expression and localization ofOATP1A2in humanRPE. Transporter functional studies were conducted to assess the interaction ofOATP1A2withatROL.Key ResultsOur study revealedOATP1A2is expressed in humanRPE, mainly at the apical membrane. Our data also indicatedatROLinhibited the uptake of the typicalOATP1A2substrate, oestrone‐3‐sulfate (E3S), in over‐expressing cells. Studies on the uptake of3H‐atROLin these over‐expressing cells revealedatROLis a substrate ofOATP1A2. We confirmed these findings in human primaryRPEcells. The transport ofE3SandatROLwas significantly reduced in human primaryRPEcells withOATP1A2siRNA silencing.Conclusion and ImplicationsOur data provides the first evidence ofOATP1A2expression in humanRPEand more importantly, its novel role in the cellular uptake ofatROL, which might be essential to the proper functioning of the canonical visual cycle. Our findings contribute to the understanding of the molecular mechanisms involved in retinoid transport between theRPEand photoreceptors and provide novel insights into potential pharmaceutical interventions for visual cycle disruption associated with retinal degenerations.
Adult, Estrone, Cell Membrane, Primary Cell Culture, Organic Anion Transporters, Biological Transport, Epithelial Cells, Retinal Pigment Epithelium, Middle Aged, Transfection, HEK293 Cells, Humans, RNA Interference, Vitamin A, Aged
Adult, Estrone, Cell Membrane, Primary Cell Culture, Organic Anion Transporters, Biological Transport, Epithelial Cells, Retinal Pigment Epithelium, Middle Aged, Transfection, HEK293 Cells, Humans, RNA Interference, Vitamin A, Aged
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