The steroid hydroxylases CYP17A1 (P450c17, 17-hydroxylase/17,20-lyase) and CYP21A2 (P450c21, 21-hydroxylase) catalyze progesterone hydroxylation at one or more sites within a 2 Å radius. We probed their hydrogen atom abstraction mechanisms and regiochemical plasticity with deuterium-labeled substrates: 17-[2H]-pregnenolone; 17-[2H]-, 16α-[2H]-, 21,21,21-[2H3]-, and 21-[2H]-progesterone; and 21,21,21-[2H3]-17-hydroxyprogesterone. Product distribution and formation rates with recombinant human P450-oxidoreductase and wild-type human CYP17A1 or mutation A105L (reduced progesterone 16α-hydroxylation) and wild-type human CYP21A2 or mutation V359A (substantial progesterone 16α-hydroxylation) were used to calculate intramolecular and intermolecular kinetic isotope effects (KIEs). The intramolecular KIEs for CYP17A1 and mutation A105L were 4.1 and 3.8, respectively, at H-17 and 2.9 and 5.1, respectively, at H-16α. Mutation A105L 21-hydroxylates progesterone (5% of products), and wild-type CYP17A1 also catalyzes a trace of 21-hydroxylation, which increases with 16α-[2H]- and 17-[2H]-progesterone. The intramolecular KIEs with CYP21A2 mutation V359A and progesterone were 6.2 and 3.8 at H-21 and H-16α, respectively. Wild-type CYP21A2 also forms a trace of 16α-hydroxyprogesterone, which increased with 21,21,21-[2H3]-progesterone substrate. Competitive intermolecular KIEs paralleled the intramolecular KIE values, with DV values of 1.4–5.1 and DV/K values of 1.8–5.1 for these reactions. CYP17A1 and CYP21A2 mutation V359A both 16α-hydroxylate 16α-[2H]-progesterone with 33–44% deuterium retention, indicating stereochemical inversion. We conclude that human CYP17A1 has progesterone 21-hydroxylase activity and human CYP21A2 has progesterone 16α-hydroxylase activity, both of which are enhanced with deuterated substrates. The transition states for C-H bond cleavage in these hydroxylation reactions are either significantly non-linear and/or asymmetric, and C-H bond breakage is partially rate-limiting for all reactions.

Ulcerative colitis (UC) is a chronic recurrent intestinal inflammatory disease characterized by high incidence and young onset age. Recently, there have been some interesting findings in the pathogenesis of UC. The mucus barrier, which is composed of a mucin complex rich in O-glycosylation, not only provides nutrients and habitat for intestinal microbes but also orchestrates the taming of germs. In turn, the gut microbiota modulates the production and secretion of mucins and stratification of the mucus layers. Active bidirectional communication between the microbiota and its ‘slimy’ partner, the mucus barrier, seems to be a continually performed concerto, maintaining homeostasis of the gut ecological microenvironment. Any abnormalities may induce a disorder in the gut community, thereby causing inflammatory damage. Our review mainly focuses on the complicated communication between the mucus barrier and gut microbiome to explore a promising new avenue for UC therapy.

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Astragaloside IV (AS-IV) is one of the main pharmacologically active compounds found in Astragalus membranaceus. AS-IV has protective effects against ischemia-reperfusion injury (IRI), but its mechanism of action has not yet been determined. This study aims to investigate the effect of AS-IV on IRI and its effect on the phosphadylinositol 3-kinase (PI3K)/Akt/heme oxygenase (HO-1) signaling pathway through in vitro experiments. Firstly, a cell culture model of myocardiocyte hypoxia-reoxygenation (H/R) injury was replicated. After AS-IV treatment, cell viability, reactive oxygen species (ROS) levels, as well as the content or activity of the cellular factors lactate dehydrogenase (LDH), superoxide dismutase (SOD), malondialdehyde (MDA), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), were measured to evaluate the effect of treatment with AS-IV. The effect of AS-IV on HO-1 protein expression and nuclear factor E2-related factor 2 (Nrf2) and Bach1 protein expression was determined by Western blotting. Finally, a reversal of the effect of AS-IV treatment was observed following co-incubation with a PI3K inhibitor. Our results show that AS-IV has good protective effect on H/R injury and has anti-oxidative stress and anti-inflammatory effects. It can regulate the expression of Nrf2 and Bach1 proteins in the nucleus and promote the expression of HO-1 protein, while a PI3K inhibitor can partially reverse the above effects. This study suggests that the PI3K/Akt/HO-1 signaling pathway may be a key signaling pathway for the anti-IRI effect of AS-IV.

Aim To measure the expression profile of circular RNA (circRNA) in hepatic tissues in a liver fibrosis model and to explore their function using molecular biology and bioinformatic techniques. Methods The classic CCl4 mouse liver fibrosis model was established alongside a normal control group. The circRNA expression profile of hepatic tissue from the two groups was compared using a high‐throughput circRNA microarray. The differentially expressed circRNAs were identified, and real‐time quantitative polymerase chain reaction (RT‐qPCR) was used to verify a subset of the differentially expressed circRNAs (target genes). At the same time, the mouse oxidative stress injury, macrophage inflammation, and hepatic stellate cell activation models were established, and the expression of target circRNA in the above cells was measured by RT‐qPCR. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to predict the biological functions of target genes. Finally, one of the circRNAs was selected and its cellular function was verified using siRNA. Results A total of 10 389 circRNAs were analyzed by microarray. Compared with the normal group, there were 69 circRNAs that were differentially expressed in the liver fibrosis model group (>2‐fold differential expression, P < 0.05), of which 14 were upregulated and 55 were downregulated. Five circRNAs and their differential expression were verified by RT‐qPCR, and the findings were consistent with the microarray results. Of these, three circRNAs were differentially expressed (P < 0.05) in the JS1 model, one circRNA was differentially expressed (P < 0.05) in the AML12 model, and four circRNAs were differentially expressed (P < 0.05) in the RAW264.7 model. The GO analysis showed that the differentially expressed circRNAs might be involved in cell autophagy, composition of extracellular matrix components, synthesis and metabolism of retinoic acid, retinol dehydrogenase activity, ubiquitin‐like protein ligase activity, histone methylation, and other biological functions. The KEGG analysis showed that the target genes of the differentially expressed circRNAs might be involved in transforming growth factor‐β1/smads, Hippo, Rap1, vascular endothelial growth factor, and other signaling pathways. Lipofection experiments showed that the expression of α‐smooth muscle actin (α‐SMA) in JS1 cells increased significantly after the expression of mmu_circ_34116 was decreased. Conclusion The circRNA expression profile in liver fibrosis tissue shows significant changes. Partially differentially expressed circRNA could be involved in hepatic fibrosis related to hepatic oxidative stress injury, macrophage inflammation, and stellate cell activation. For instance, mmu_circ_34116 can significantly inhibit the activation of hepatic stellate cells.

Photodynamic therapy (PDT), which utilizes reactive oxygen species to ablate tumor, has attracted much attention in recent years. Photosensitizers with near-infrared (NIR) fluorescence as well as efficient ROS generation ability have been used for precise diagnosis and simultaneous treatment of cancer. However, photosensitizers frequently suffer from low ROS generation ability and NIR fluorescence quenching in aqueous media due to the aggregation. Methods: We prepare an effective AIE active NIR emissive photosensitizer containing rhodanine as electron acceptor and triphenylvinylthiophene as electron donor is prepared, and encapsulate the corresponding photosensitizer into Pluronic F127 to fabricate NIR organic fluorescent nanoparticles. We then evaluate the NIR fluorescence bioimaging and photodynamic therapy ability of TPVTR dots in vitro and in vivo. Results: The yielded organic fluorescent nanoparticles exhibit effective ROS generation ability, bright NIR emission, high photostability, and good biocompatibility. Both in vitro and in vivo experiments confirm that NIR organic fluorescent nanoparticles demonstrate good performances in long-term tracing and photodynamic ablation of tumor. Conclusion: In summary, the synthesized organic fluorescent nanoparticles, TPVTR dots, showed great potentials in long-term cell tracing and photodynamic therapy of tumor. Our study highlights the efficient strategy for developing promising near-infrared organic fluorescent nanoparticles in advancing the field of bioimaging and further image-guide clinical applications.