A Role for ABCC4 in Regulating Pigment Granule Aggregation in Mice

Abstract

ABCC4 is member of the family of ATP‐binding cassette proteins that specialize in transporting a variety of molecules out of the cell. ABCC4 exports signaling molecules present in the retina, including cyclic adenosine monophosphate (cyclic AMP). In fish, cyclic AMP regulates processes in the retinal pigment epithelium (RPE), such as dark‐adaptive pigment granule aggregation. In mammals, cyclic AMP accumulates in photoreceptors in the dark. If cyclic AMP were exported from the photoreceptors into the sub‐retinal space, it could then be available for uptake by the RPE, in which it could activate processes that drive pigment granule aggregation. We hypothesize that ABCC4 in photoreceptors mediates cAMP‐export and is needed for pigment granule migration in mice. To investigate ABCC4's involvement in pigment granule aggregation in mice, pigment granule density was measured along the basal microvilli in the RPE in both wildtype (N=3) and Abcc4 knockout mice (N=3). Pigment granule densities measured in the RPE of wild type, dark‐adapted mice differed significantly from those measured in wildtype, light‐adapted mice (p‐value = 0.02). In contrast, pigment granule density was not statistically significantly different between Abcc4 knockout mice that had been dark‐adapted or light‐adapted (p‐value = 0.13). These results support the hypothesis that ABCC4 is involved in the process of pigment granule migration in mice and are consistent with a novel role for cyclic AMP as a cell‐to cell signaling molecule in the retina.Support or Funding InformationThis project was supported by Texas State University in the form of an undergraduate research fellowship to AMP and funds from the Office of the Provost awarded to DMG in recognition of her service as Presidential Fellow. DEI received salary support from HSI STEM Program (84.031c) Award #P031C160035.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.