Expression of adenosine receptors in human retinal pigment epithelium cells in vitro.

Background: Adenosine receptors (ADORs) have been reported to play a role in experimental myopia. This study aimed to determine the distribution of ADORs in human retinal pigment epithelium (RPE) cells cultured in vitro.
Methods: Human RPE cells (cell line D407) were cultured in vitro. ADOR mRNA in RPE was detected by reverse transcription polymerase chain reaction. ADOR protein expression in RPE was confirmed by Western blotting analysis of cell lysates. Confocal fluorescence microscopy was used to study the subcellular distribution of ADORs.
Results: All four subtypes of ADORs mRNA and protein were expressed in human RPE. This was confirmed by Western blotting analysis. The ADOR subtypes were differently distributed within the cells. ADORA1 was expressed in nucleus, perinucleus and cytoplasm of RPE. ADORA2A was concentrated mainly in one side of the perinucleus and cytoplasm of RPE. ADORA2B was strongly expressed in the nucleus, perinucleus and the cytoplasm, and ADORA3 was expressed weakly in the cytoplasm of RPE.
Conclusions: ADORs are expressed in human RPE. The different distribution at the subcellular level suggests different functions of ADOR subtypes.