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

Dysregulation of CRY1 impairs brain thyroid hormone pathway and promotes anxiety-like behavior in male mice

BACKGROUND

The circadian clock system plays a crucial role in influencing mood and behavior, with the clock gene Cry1 serving as a core component of the molecular circadian clock. However, the role of CRY1 in anxiety-related behaviors and their underlying mechanisms are poorly understood.

METHODS AND RESULTS

In this study, we investigated the role of CRY1 in anxiety-related behaviors through various behavioral approaches, and assessed potential molecular alterations in key brain regions involved in behavioral responses. We found that male Cry1-/- (Cry1 knockout) mice developed anxiety-like behavior in both stressed and non-stressed conditions. Administration of CRY1 stabilizer KL201 significantly alleviated anxiety-like behavior in male mice. Further studies suggested involvement of the brain thyroid hormone signaling in CRY1 regulation of anxiety-like behavior, evidenced by markedly reduced brain T3 levels relation to down-regulation of OATP1C1 and DIO2 mediated by CRY1, which underlies neurogenesis deficits and contributes to anxiety. Subsequent in vivo and cell-based experiments confirmed that CRY1 positively regulates the expression of OATP1C1 and DIO2. Mechanistically, CRY1 regulates OATP1C1 and DIO2 through regulating the transcriptional activity of E4BP4. E4BP4 trans-inactivates OATP1C1 and DIO2 via direct binding to its specific response element in the gene promoters.

CONCLUSION

These findings underscore the critical role of CRY1 in regulating thyroid hormone and anxiety, providing insight into the underlying pathogenesis and potential treatment strategies for mood disorders.

Farnesoid X receptor regulates CYP1A1 and CYP1B1 and estradiol metabolism in mouse and human cell lines

Human CYP1A1 and CYP1B1 are two important enzymes for the hydroxylation of estrogens. In this study, we aimed to investigate the potential role for FXR receptor in the regulation of CYP1A1 and CYP1B1 expressions and activities. First, pharmacokinetic analysis was conducted in male wild-type and Fxr-/- mice after intraperitoneal dosing of exogenous estradiol. In vitro microsomal Cyp1a1 and Cyp1b1 activities were probed using their substrates estradiol, phenacetin, and melatonin. The regulatory effects of FXR on these two enzymes were explored using female Fxr-/- mice, mouse 4T1 and human MCF-7 cell lines. As a result, Fxr-deficiency significantly changed the plasma concentration-time curve and exposure (AUC0-2 h) of estradiol, and the metabolism ratios of its hydroxylated metabolites. Global deletion of Fxr led to significant down-regulation of Cyp1a1 and Cyp1b1 mRNA and protein in major organs (liver, lung, kidney, stomach, small intestine). Overexpression of Fxr in mouse 4T1 cells resulted in increased levels of Cyp1a1 and Cyp1b1 mRNA and protein, whereas Fxr knockdown caused down-regulation of Cyp1a1 and Cyp1b1 expression. In human MCF-7 cells, there was a similar regulatory trend of FXR towards CYP1A1 and CYP1B1 as well as those in mouse 4T1 cells. In vitro incubation assays also supported these results. Based on luciferase reporter and electrophoretic mobility shift assays, Fxr directly activated Cyp1a1 and Cyp1b1 via their specific binding to (-488 ∼ -477 bp) and (-1475 ∼ -1460 bp) regions in their promoters, respectively. Therefore, FXR transcriptionally regulates the expression of CYP1A1 and CYP1B1, impacting the in vitro metabolism and pharmacokinetics of their substrates.

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.