The Light-Inducible Genes Per2, Cry1a, and Cry2a Regulate Oxidative Status in Zebrafish

The circadian clock is a highly conserved 24 h biological oscillation mechanism and is affected by environmental stimuli such as light, food and temperature. Disruption of the circadian clock results in disorders of diverse biological processes, including the sleep-wake cycle and metabolism. Although we previously identified several components of the circadian clock in zebrafish, our understanding of the relationship between light-inducible clock genes and metabolism remains incomplete. To investigate how light-inducible clock genes regulate metabolism, we performed transcriptomic and metabolomic analyses of the light-inducible clock genes zPer2, zCry1a, and zCry2a in zebrafish. Transcriptomic analysis of zPer2/zCry1a double knockout (DKO) and zPer2/zCry1a/zCry2a triple knockout (TKO) mutants showed that their gene expression profiles differed from that of wild type (WT) zebrafish. In particular, mRNA levels of zKeap1a, which encodes an oxidative stress sensor, were increased in DKO and TKO mutants. Metabolomic analysis showed genotype-dependent alteration of metabolomic profiles. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) showed the alteration of cysteine/methionine metabolism and glutathione metabolism. Specifically, cysteine and glutathione were decreased but methionine sulfoxide was increased in TKO zebrafish. These results indicate that the light-inducible genes zPer2, zCry1a, and zCry2a are involved in regulating the oxidative status of zebrafish.