Genes involved in energy metabolism are differentially expressed during the day–night cycle in murine retinal pigment epithelium

Elja M.M. Louer, Guoqiang Yi, Claudia Carmone, Joris Robben, Henk G. Stunnenberg, Anneke I. den Hollander, Peter M.T. Deen

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10 Citations (Scopus)


PURPOSE. The functional interaction between photoreceptors and retinal pigment epithelium (RPE) cells is essential for vision. Phagocytosis of photoreceptor outer segments (POSs) by the RPE follows a circadian pattern; however, it remains unknown whether other RPE processes follow a daily rhythm. Therefore, our aim was to identify RPE processes following a daily rhythm. METHODS. Murine RPE was isolated at Zeitgeber time (ZT) 0, 2, 4, 9, 14, and 19 (n = 5 per time point), after which RNA was isolated and sequenced. Genes with a significant difference in expression between time points (P < 0.05) were subjected to EnrichR pathway analysis to identify daily rhythmic processes. RESULTS. Pathway enrichment revealed 13 significantly enriched KEGG pathways (P < 0.01), including the metabolic pathway (P = 0.002821). Analysis of the metabolic pathway differentially expressed genes revealed that genes involved in adenosine triphosphate production, glycolysis, glycogenolysis, and glycerophospholipid were low at ZT0 (light onset) and high at ZT19 (night). Genes involved in fatty acid degradation and cholesterol synthesis were high at light onset and low at night. CONCLUSIONS. Our transcriptome data suggest that the highest energy demand of RPE cells is at night, whereas POS phagocytosis and degradation take place in the morning. Furthermore, we identified genes involved in fatty acid and glycerophospholipid synthesis that are upregulated at night, possibly playing a role in generating building blocks for membrane synthesis.

Original languageEnglish
Article number49
JournalInvestigative Ophthalmology and Visual Science
Issue number5
Publication statusPublished - May 2020
Externally publishedYes


  • Circadian rhythm
  • Day–night cycle
  • Metabolism
  • Retinal pigment epithelium
  • RNA-sequencing


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