Heteromeric complex formation between human cytochrome P450 CYP1A1 and heme oxygenase-1

Functional characterization of CYP1 enzymes: Complex formation, membrane localization and function

CYP1A1, CYP1A2, and CYP1B1 have a high degree of sequence similarity, similar substrate selectivities and induction characteristics. However, experiments suggest that there are significant differences in their quaternary structures and function. The goal of this study was to characterize the CYP1 proteins regarding their ability to form protein-protein complexes, lipid microdomain localization, and ultimately function. This was accomplished by examining (1) substrate metabolism of the CYP1s as a function of NADPH-cytochrome P450 reductase (POR) concentration, and (2) quaternary structure, using bioluminescence resonance energy transfer (BRET). Both CYP1As were able to form BRET-detectable homomeric complexes, which was not observed with CYP1B1. When activities were measured as a function of [POR], CYP1A1 and CYP1B1 showed a hyperbolic response, consistent with mass-action binding; however, CYP1A2 produced a sigmoidal response, suggesting that the homomeric complex affected its function. Differences were observed in their ability to form heteromeric complexes. Whereas CYP1B1 and CYP1A1 formed a complex, neither the CYP1A1/CYP1A2 nor the CYP1B1/CYP1A2 pair formed BRET-detectable complexes. These proteins also differed in their lipid microdomain localization, with CYP1A2 and CYP1B1 residing in ordered membranes, and CYP1A1 in the disordered lipid regions. Taken together, despite their sequence similarities, there are substantial differences in quaternary structures and microdomain localization that can influence enzymatic activities. As these proteins exist in the endoplasmic reticulum with other ER-resident proteins, the P450s need to be considered as part of multi-enzyme systems rather than simply monomeric proteins interacting with their redox partners.

Network pharmacology-based analysis of heat clearing and detoxifying drug JC724 on the treatment of colorectal cancer

BACKGROUND

Heat-clearing and detoxifying drugs has protective effect on colorectal cancer (CRC). Given the complicated features of Traditional Chinese medicine formulas, network pharmacology is an effective approach for studying the multiple interactions between drugs and diseases.

AIM

To systematically explore the anticancer mechanism of heat-clearing and detoxifying drug JC724.

METHODS

This study obtained the active compounds and their targets in JC724 from Traditional Chinese Medicine System Pharmacology Database. In addition, the CRC targets were obtained from Drugbank, TTD, DisGeNET and GeneCards databases. We performed transcriptome analysis of differentially expressed genes in CRC treated with JC724. Venn diagram was used to screen the JC724-CRC intersection targets as candidate targets. Core targets were selected by protein-protein interaction network and herb ingredient-target-disease network analysis. The functional and pathway of core targets were analysed by enrichment analysis.

RESULTS

We found 174 active ingredients and 283 compound targets from JC724. 940 CRC-related targets were reserved from the four databases and 304 CRC differentially expressed genes were obtained by transcriptome analysis. We constructed the network and found that the five core ingredients were quercetin, β Beta sitosterol, wogonin, kaempferol and baicalein. The core JC724-CRC targets were CYP1A1, HMOX1, CXCL8, NQO1 and FOSL1. JC724 acts on multiple signaling pathways associated with CRC, including the Nrf2 signaling pathway, oxidative stress, and the IL-17 signaling pathway.

CONCLUSION

In this study, we systematically analyzed the active ingredients, core targets and main mechanisms of JC724 in the treatment of CRC. This study could bring a new perspective to the heat-clearing and detoxifying therapy of CRC.

Identification of herbal teas and their compounds eliciting antiviral activity against SARS-CoV-2 in vitro

BACKGROUND

The SARS-CoV-2/COVID-19 pandemic has inflicted medical and socioeconomic havoc, and despite the current availability of vaccines and broad implementation of vaccination programs, more easily accessible and cost-effective acute treatment options preventing morbidity and mortality are urgently needed. Herbal teas have historically and recurrently been applied as self-medication for prophylaxis, therapy, and symptom alleviation in diverse diseases, including those caused by respiratory viruses, and have provided sources of natural products as basis for the development of therapeutic agents. To identify affordable, ubiquitously available, and effective treatments, we tested herbs consumed worldwide as herbal teas regarding their antiviral activity against SARS-CoV-2.

RESULTS

Aqueous infusions prepared by boiling leaves of the Lamiaceae perilla and sage elicit potent and sustained antiviral activity against SARS-CoV-2 when applied after infection as well as prior to infection of cells. The herbal infusions exerted in vitro antiviral effects comparable to interferon-β and remdesivir but outperformed convalescent sera and interferon-α2 upon short-term treatment early after infection. Based on protein fractionation analyses, we identified caffeic acid, perilla aldehyde, and perillyl alcohol as antiviral compounds. Global mass spectrometry (MS) analyses performed comparatively in two different cell culture infection models revealed changes of the proteome upon treatment with herbal infusions and provided insights into the mode of action. As inferred by the MS data, induction of heme oxygenase 1 (HMOX-1) was confirmed as effector mechanism by the antiviral activity of the HMOX-1-inducing compounds sulforaphane and fraxetin.

CONCLUSIONS

In conclusion, herbal teas based on perilla and sage exhibit antiviral activity against SARS-CoV-2 including variants of concern such as Alpha, Beta, Delta, and Omicron, and we identified HMOX-1 as potential therapeutic target. Given that perilla and sage have been suggested as treatment options for various diseases, our dataset may constitute a valuable resource also for future research beyond virology.

Exploring the Interactome of Cytochrome P450 2E1 in Human Liver Microsomes with Chemical Crosslinking Mass Spectrometry

Aiming to elucidate the system-wide effects of the alcohol-induced increase in the content of cytochrome P450 2E1 (CYP2E1) on drug metabolism, we explored the array of its protein-protein interactions (interactome) in human liver microsomes (HLM) with chemical crosslinking mass spectrometry (CXMS). Our strategy employs membrane incorporation of purified CYP2E1 modified with photoreactive crosslinkers benzophenone-4-maleimide and 4-(N-succinimidylcarboxy)benzophenone. Exposure of bait-incorporated HLM samples to light was followed by isolating the His-tagged bait protein and its crosslinked aggregates on Ni-NTA agarose. Analyzing the individual bands of SDS-PAGE slabs of thereby isolated protein with the toolset of untargeted proteomics, we detected the crosslinked dimeric and trimeric complexes of CYP2E1 with other drug-metabolizing enzymes. Among the most extensively crosslinked partners of CYP2E1 are the cytochromes P450 2A6, 2C8, 3A4, 4A11, and 4F2, UDP-glucuronosyltransferases (UGTs) 1A and 2B, fatty aldehyde dehydrogenase (ALDH3A2), epoxide hydrolase 1 (EPHX1), disulfide oxidase 1α (ERO1L), and ribophorin II (RPN2). These results demonstrate the exploratory power of the proposed CXMS strategy and corroborate the concept of tight functional integration in the human drug-metabolizing ensemble through protein-protein interactions of the constituting enzymes.

Assembling the P450 puzzle: on the sources of nonadditivity in drug metabolism

There is an increasing number of indications of an oversimplification in the premise that the cumulative properties of the human drug-metabolizing ensemble represent a simple aggregate of the properties of the constituting enzymes. Recent studies of the functional effects of hetero-association of multiple cytochrome P450 species and their interactions with metabolically related enzymes revealed a tight integration in the drug-metabolizing ensemble. In our opinion, the sources of interindividual variability in drug metabolism can be elucidated only when considering this ensemble as a multienzyme system, the functional parameters of which are determined by interactions between its constituents. In this article, we present a conceptual model providing a mechanistic explanation for the functional effects of the interactions between multiple P450 species and propose a clue to understanding the nonadditive behavior of the drug-metabolizing ensemble.

Combined adjuvant effects of ambient vapor-phase organic components and particulate matter potently promote allergic sensitization and Th2-skewing cytokine and chemokine milieux in mice: The importance of mechanistic multi-pollutant research

Although exposure to ambient particulate matter (PM) is linked to asthma, the health effects of co-existing vapor-phase organic pollutants (vapor) and their combined effects with PM on this disease are poorly understood. We used a murine asthma model to test the hypothesis that exposure to vapor would enhance allergic sensitization and this effect would be further strengthened by co-existing PM. We found that vapor and PM each individually exerted adjuvant effects on OVA sensitization. Co-exposure to vapor and PM during sensitization further enhanced allergic lung inflammation and OVA-specific antibody production which was accompanied by pulmonary cytokine/chemokine milieu that favored T-helper 2 immunity (i.e. increased IL-4, downregulation of Il12a and Ifng, and upregulation of Ccl11 and Ccl8). TNFα, IL-6, Ccl12, Cxcl1 and detoxification/antioxidant enzyme responses in the lung were pollutant-dependent. Inhibition of lipopolysaccharide-induced IL-12 secretion from primary antigen-presenting dendritic cells correlated positively with vapor's oxidant potential. In conclusion, concurrent exposure to vapor and PM led to significantly exaggerated adjuvant effects on allergic lung inflammation which were more potent than that of each pollutant type alone. These findings suggest that the effects of multi-component air pollution on asthma may be significantly underestimated if research only focuses on a single air pollutant (e.g., PM).