CRY1/2 regulate rhythmic CYP2A5 in mouse liver through repression of E4BP4

Disruption of local circadian clocks in aristolochic acid-induced nephropathy in mice

BACKGROUND

Aristolochic acid I (AAI), an emerging biogenic contaminant widely present in Aristolochic plants, has been implicated in the progression of tubulointerstitial disease, known as aristolochic acid nephropathy (AAN). The circadian clock, a vital regulator of organ homeostasis, is susceptible to external chemical cues, including toxins. However, the reciprocal interactions between AAI and the circadian clock remain unexplored.

METHODS

We initially assessed sex- and time-dependent nephropathy and behavioral responses in C57BL/6J mice exposed to AAI. Subsequently, we evaluated changes in the expression of circadian clock genes following treatment with AAI or its bioactive metabolite, aristolactam I, using real-time quantitative PCR and immunoblotting in renal tissues and cells. Additionally, real-time reporter assays were conducted on kidney explants from PER2::Luc knock-in reporter mice and Per2-dLuc/Bmal1-dLuc reporter cell lines. To further elucidate the regulatory role of circadian clocks in AAI-induced nephropathy, mice with global or kidney-specific knockout of Bmal1, as well as mice subjected to experimental jetlag, were utilized.

RESULTS

Our findings revealed a sex-dependent nephrotoxicity of AAI, with males exhibiting greater vulnerability. AAI-induced nephropathy was accompanied by impaired spatial cognitive function, disruptions in free-running locomotor activity, altered renal expression of multiple core clock genes, and disturbances in the circadian rhythm of renal PER2::Luc activity. Notably, kidney-specific ablation of the core clock gene Bmal1 significantly exacerbated renal injury and inflammation, whereas disruptions to the central clock, either genetically (through conventional knockout of Bmal1) or environmentally (mimicking jetlag), had minimal effects on AAI nephrotoxicity. Furthermore, both AAI and its bioactive metabolite aristolactam I demonstrated the ability to disrupt circadian clocks in human osteosarcoma cells (U2OS) and mouse renal tubular epithelial cells (mRTEC).

CONCLUSION

Collectively, these findings highlight the detrimental impact of aristolochic acids on local renal circadian clocks, ultimately exacerbating kidney damage. This study provides novel insights into the molecular mechanisms underlying AAI nephrotoxicity, potentially opening avenues for therapeutic interventions aimed at modulating the renal circadian clock to treat AAN.

The role of the circadian timing system on drug metabolism and detoxification: an update

INTRODUCTION

The 24-hour variations in drug absorption, distribution, metabolism, and elimination, collectively known as pharmacokinetics, are fundamentally influenced by rhythmic physiological processes regulated by the molecular clock. Recent advances have elucidated the intricacies of the circadian timing system and the molecular interplay between biological clocks, enzymes and transporters in preclinical level.

AREA COVERED

Circadian rhythm of the drug metabolizing enzymes and carrier efflux functions possess a major role for drug metabolism and detoxification. The efflux and metabolism function of intestines and liver seems important. The investigations revealed that the ABC and SLC transporter families, along with cytochrome p-450 systems in the intestine, liver, and kidney, play a dominant role in the circadian detoxification of drugs. Additionally, the circadian control of efflux by the blood-brain barrier is also discussed.

EXPERT OPINION

The influence of the circadian timing system on drug pharmacokinetics significantly impacts the efficacy, adverse effects, and toxicity profiles of various drugs. Moreover, the emergence of sex-related circadian changes in the metabolism and detoxification processes has underscored the importance of considering gender-specific differences in drug tolerability and pharmacology. A better understanding of coupling between central clock and circadian metabolism/transport contributes to the development of more rational drug utilization and the implementation of chronotherapy applications.

Circadian rhythms in CYP2A5 expression underlie the time-dependent effect of tegafur on breast cancer

The chemotherapeutic agent tegafur, a prodrug that prolongs the half-life of fluorouracil (5-FU), exerts antitumor effects against various cancers. Since tegafur is metabolized to 5-FU by CYP2A6 in the liver, the expression of CYP2A6 determines the effect of tegafur. Here, we report that the expression rhythm of Cyp2a5, a homolog of human CYP2A6, in female mice causes dosing time-dependent differences in tegafur metabolism. In the livers of female mice, CYP2A5 expression showed a circadian rhythm, peaking during the dark period. This rhythm is regulated by RORA, a core clock component, and abrogation of the CYP2A5 activity abolished the time-dependent difference in the rate of tegafur metabolism in female mice. Furthermore, administration of tegafur to mice transplanted with 4T1 breast cancer cells during the dark period suppressed increases in tumor size compared to female mice treated during the light period. Our findings reveal a novel relationship between 5-FU prodrugs and circadian clock machinery, potentially influencing antitumor effects, and contributing to the development of time-aware chemotherapy regimens for breast cancer.