CYP2A5 , an enzyme responsible for metabolism of diverse drugs, displays circadian rhythms in its expression and activity. However, the underlying mechanisms are not fully established. Here we aimed to investigate a potential role of CRY1/2 (circadian clock modulators) in circadian regulation of hepatic CYP2A5. Regulatory effects of CRY1/2 on CYP2A5 were determined using Cry1 -null and Cry2 -null mice, and validated using AML-12, Hepa1-6 and HepG2 cells. CYP2A5 activities both in vivo and in vitro were assessed using coumarin 7-hydroxylation as a probe reaction. mRNA and protein levels were detected by qPCR and western blotting , respectively. Regulatory mechanism was studied using a combination of luciferase reporter assays, chromatin immunoprecipitation (ChIP) and co-immunoprecipitation (Co-IP). We found that ablation of Cry1 or Cry2 in mice reduced hepatic CYP2A5 expression (at both mRNA and protein levels) and blunted its diurnal rhythms. Consistently, these knockouts showed decreased CYP2A5 activity (characterised by coumarin 7-hydroxylation) and a loss of its time-dependency, as well as exacerbated coumarin-induced hepatotoxicity. Cell-based assays confirmed that CRY1/2 positively regulated CYP2A5 expression and rhythms. Based on combined luciferase reporter, ChIP and Co-IP assays, we unraveled that CRY1/2 interacted with E4BP4 protein to repress its inhibitory effect on Cyp2a5 transcription and expression . In conclusion, CRY1/2 regulate rhythmic CYP2A5 in mouse liver through repression of E4BP4. These findings advance our understanding of circadian regulation of drug metabolism and pharmacokinetics .
Human cytochrome P450 (CYP) 2A6 participates in the metabolism of nicotine and precarcinogens, thus the deliberate inhibition of CYP2A6 may reduce cigarette consumption and therefore reduce the risk of developing the types of cancer associated with smoking. The inhibitory effects and mechanisms of celery (Apium graveolens) extract on mouse CYP2A5 and human CYP2A6 activity remain unclear. These effects were investigated in mouse and human liver microsomes using coumarin 7‑hydroxylation in a probe reaction. Celery extract reduced CYP2A5 and CYP2A6 activities in vitro in a dose‑dependent manner. In vivo experiments also showed that celery extract markedly decreased CYP2A5 activity. The inhibition of celery extract on CYP2A5 was time‑ and nicotinamide adenine dinucleotide phosphate (NADPH)‑independent, and was markedly reduced by ultracentrifugation. Additionally, the inhibition of celery extract on CYP2A6 was time and NADPH‑dependent. Levels of inhibition were characterized by a Ki, the measure of the tightness of bonds between the enzyme and its inhibitor, of 266.4 µg/ml for CYP2A5, and a Ki of 1,018 µg/ml and Kinact of 0.3/min for CYP2A6. Kinact is the maximal rate of enzyme inactivation at a saturating concentration of inhibitor. The coumarin derivative 5‑methoxypsoralen present in celery extract did not solely to the inhibition of CYP2A5/6 activity. In conclusion, celery extract inhibited the levels of mouse CYP2A5 and human CYP2A6 activity via different mechanisms: Mixed competitive inhibition for CYP2A5 and mechanism‑based inhibition for CYP2A6.
Jingru Wang,Jiaxin Yang,Yanyan Li,Yang Li,Rui Xu,Feng Song
The widespread application of optical encryption materials with difficult imitation, multicolor-tunable emission and simple operation presents a promising strategy for secure communication and authentication of information. Herein, Eu-MOF grafted with coumarin 7 is successfully constructed through self-assembly process and a prismatic three-dimensional hyperbranched structure is formed. At room temperature, it can be excited to by ultraviolet light significantly different green and red light emission. With the temperature rising to 363 K, under the excitation of 360 nm, a continuous and programmable color transformation occurs, resulting in a fitted line with a fitting degree of 0.99745. In order to maintain robust reliability, regular alterations in accordance with temperature variations are assessed through temperature sensitivity, and the absolute sensitivity and relative sensitivity can reach up to 6.168 % K −1 and 4.387 % K −1 . Based on the abundant emission modes, we develop an asymmetric information security authentication program to simulate encrypted information communication, which provides reliable guidance on visualized information storage and encryption.
危险品化学品经营许可证（带存储）