Target Fishing Reveals a Novel Mechanism of 1,2,4-Oxadiazole Derivatives Targeting Rpn6, a Subunit of 26S Proteasome

1,2,4-Oxadiazole derivatives, a class of Nrf2-ARE activators, exert an extensive therapeutic effect on inflammation, cancer, neurodegeneration, and microbial infection. Among these analogues, DDO-7263 is the most potent Nrf2 activator and used as the core structure for bioactive probes to explore the precise mechanism. In this work, we obtained compound 7, a mimic of DDO-7263, and biotin-labeled and fluorescein-based probes, which exhibited homologous biological activities to DDO-7263, including activating Nrf2 and its downstream target genes, anti-oxidative stress, and anti-inflammatory effects. Affinity chromatography and mass analysis techniques revealed Rpn6 as the potential target protein regulating the Nrf2 signaling pathway. In vitro affinity experiments further confirmed that DDO-7263 upregulated Nrf2 through binding to Rpn6 to block the assembly of 26S proteasome and the subsequent degradation of ubiquitinated Nrf2. These results indicated that Rpn6 is a promising candidate target to activate the Nrf2 pathway for protecting cells and tissues from oxidative, electrophilic, and exogenous microbial stimulation.

Advances in Cryochemistry: Mechanisms, Reactions and Applications

It is counterintuitive that chemical reactions can be accelerated by freezing, but this amazing phenomenon was discovered as early as the 1960s. In frozen systems, the increase in reaction rate is caused by various mechanisms and the freeze concentration effect is the main reason for the observed acceleration. Some accelerated reactions have great application value in the chemistry synthesis and environmental fields; at the same time, certain reactions accelerated at low temperature during the storage of food, medicine, and biological products should cause concern. The study of reactions accelerated by freezing will overturn common sense and provide a new strategy for researchers in the chemistry field. In this review, we mainly introduce various mechanisms for accelerating reactions induced by freezing and summarize a variety of accelerated cryochemical reactions and their applications.

Development of Novel Tetrahydroquinoline Inhibitors of NLRP3 Inflammasome for Potential Treatment of DSS-Induced Mouse Colitis

The NLRP3 inflammasome is a critical component of innate immunity, which defends internal and external threats. However, inappropriate activation of the NLRP3 inflammasome induces various human diseases. In this study, we discovered and synthesized a series of tetrahydroquinoline inhibitors of NLRP3 inflammasome. Among these analogues, compound 6 exhibited optimal NLRP3 inhibitory activity. In vitro studies indicated that compound 6 directly bound to the NACHT domain of NLRP3 but not to protein pyrin domain (PYD) or LRR domain, inhibited NLRP3 ATPase activity, and blocked ASC oligomerization, thereby inhibiting NLRP3 inflammasome assembly and activation. Compound 6 specifically inhibited the NLRP3 inflammasome activation, but had no effect on the activation of NLRC4 or AIM2 inflammasomes. Furthermore, in the dextran sulfate sodium (DSS)-induced colitis mouse model, compound 6 exhibited significant anti-inflammatory activity through inhibiting NLRP3 inflammasome in vivo. Therefore, our study provides a potent NLRP3 inflammasome inhibitor, which deserves further structural optimization as a novel therapeutic candidate for NLRP3-driven diseases.

[The pathological characters of urothelial barrier in prostatic ducts of elderly SD rats]

Objective: To investigate the pathological characters of urothelial barrier in prostatic ducts of elderly male SD rats. Methods: Ten elderly male SD rats were anesthetized with chloral hydrate and then took the bladder, prostatic urethra and prostate tissues for serial pathological sections and HE staining. Immunohistochemical method was used to detect the expression of the Cytokeratin 7 (CK7), Cytokeratin 20 (CK20), Uroplakin Ⅲ (UP Ⅲ), Zonula occludens-1 (ZO-1) and Occludin in issues, and to make densitometric analysis (IA) on immunohistochemical results of each antibody. Results: HE staining observed that urothelial umbrella cells exist in the bladder, prostatic urethra and proximal prostatic duct. Immunohistochemical method showed the CK7, UPⅢ, ZO-1 and Occludin were positive in bladder, prostatic urethra and prostatic duct, while CK20 was negative. CK7 and UPⅢ were positive in the proximal prostatic duct, and negative in the bottom of the ductal acinar lumen; ZO-1 and Occludin were positive in prostatic duct. The IOD/Area values of CK7 and UP Ⅲ, in bladder, prostatic urethra, proximal prostatic duct, the middle of prostatic duct and bottom of the ductal acinar lumen, were 0.16, 0.13, 0.06, 0.05, 0.00 and 0.17, 0.16, 0.08, 0.05, 0.00(P<0.05,respectively). The expression of ZO-1 and Occludin in bladder (0.14 and 0.13) were higher than those in other tissues (0.11-0.12 and 0.09-0.10, P<0.05); the expression of ZO-1 and Occludin, which in proximal prostatic duct to the middle of prostatic duct and bottom of the ductal acinar lumen, had no significant difference (0.12-0.11 and 0.09-0.09, P>0.05). The IA values of CK20 were extremely low (0.00-0.01, P>0.05). Conclusion: Urothelial barriers partially exist in the prostatic ducts of elderly male SD rats, and with the prostatic ducts gradually extending to the bottom of acinar lumen, the urothelial barriers disappear. The results lay a foundation for further study on the repair of urinary epithelial barrier after prostatectomy.