Constitutive Expression of HCA₂ in Human Retina and Primary Human Retinal Pigment Epithelial Cells

Abstract

Purpose/Aim: HCA₂, a receptor of β-hydroxybutyrate and niacin, has recently been described in mouse retina and immortalized human retinal pigment epithelial (RPE) cell lines. As HCA₂ might be a pharmacologic target, e.g. in diabetic retinopathy, we studied its expression in human retina and primary human RPE cells.

Materials and methods: Paraffin sections of human retina and primary human RPE cells were obtained from human donor eyes. Expression of HCA₂ in human retina was investigated by immunohistochemistry of paraffin sections and by RT-PCR. HCA₂ expression in primary human RPE cells was examined by immunocytochemistry and by Western-blot analysis.

Results: Positive immunohistochemical staining for HCA₂ was found in paraffin sections of human retina, and positive immunocytochemical staining for HCA₂ in primary human RPE cells. RT-PCR analysis detected mRNA expression of HCA₂ in human retina. The expression of HCA₂ protein was found in primary human RPE cells.

Conclusions: Based on these results, HCA₂ appears to be constitutively expressed in human retina and in primary human RPE cells. Although its functional role is still unknown, HCA₂ may be potentially involved in the pathogenesis of various retinopathies and may offer a new therapeutic target.

• AMD
• diabetic retinopathy
• niacin maculopathy
• retina
• RPE