Vitamin A/retinol (ROL) and its metabolites (retinoids) play critical roles in eye development and photoreception. Short-term dietary vitamin A deficiency (VAD) manifests clinically as night blindness, while prolonged VAD is known to cause retinal pigment epithelium (RPE) and photoreceptor degeneration. Therefore, sustained uptake of dietary vitamin A, for ocular retinoid production, is essential for photoreceptor health and visual function. The mechanisms influencing the uptake, storage, and supply of dietary vitamin A, for ocular retinoid production, however, are not fully understood. We investigated, in zebrafish, the physiological role of the retinol-binding protein receptor 2 (Rbpr2), for the uptake of dietary ROL, which is necessary for vision. NIH3T3 cells expressing zebrafish Rbpr2 showed plasma membrane localization patterns and were capable of ROL uptake from its bound form. Using whole-mount in situ hybridization, Rbpr2 was found to be expressed exclusively in the liver, intestine, and pancreas, of staged zebrafish larvae. At 5.5 days post fertilization, TALEN-generated rbpr2 mutants (rbpr2 −/− ) had smaller eyes and shorter OS lengths and showed loss of PNA (cones) and rhodopsin (rods) by immunofluorescence staining. Finally, tests for visual function using optokinetic response (OKR) showed no consistent OKR in rbpr2 −/− larval zebrafish. Our analysis, therefore, suggests that Rbpr2 is capable of ROL uptake and loss of this membrane receptor in zebrafish results in photoreceptor defects that adversely affect visual function.
|Original language||English (US)|
|Title of host publication||Advances in Experimental Medicine and Biology|
|Publisher||Springer New York LLC|
|Number of pages||8|
|State||Published - 2018|
|Name||Advances in Experimental Medicine and Biology|
Bibliographical noteFunding Information:
Acknowledgments This study was supported by NIH grant EY025034-02 (GPL) and, in part, by a Knights Templar Eye Foundation Career-Starter Grant (GPL) and a Knights Templar Eye Foundation Career-Renewal Grant (GPL), NIH grant DK074038 (JHL), and a VA Merit award 2I01BX000820 (JHL).
© 2018, Springer International Publishing AG, part of Springer Nature.
- Vitamin A