Photoreceptor cells display a daily rhythm in the orphan receptor Esrrβ

PURPOSE Nuclear orphan receptors are critical for the development and long-term survival of photoreceptor cells. In the present study, the expression of the nuclear orphan receptor Esrrβ--a transcriptional regulator of energy metabolism that protects rod photoreceptors from dystrophy--was tested under daily regulation in the retina and photoreceptor cells. METHODS The daily transcript and protein amount profiles were recorded in preparations of the whole retina and microdissected photoreceptor cells using quantitative PCR (qPCR) and western blot analysis. RESULTS Esrrβ displayed a daily rhythm with elevated values at night in the whole retina and enriched photoreceptor cells. Daily regulation of Esrrβ mRNA depended on light input but not on melatonin, and evoked a corresponding rhythm in the Esrrβ protein. CONCLUSIONS The data presented in this study indicate that daily regulation of Esrrβ in photoreceptor cells may contribute to their adaptation to 24-h changes in metabolic demands.