Live-Cell Imaging of Endogenous RNA with a Genetically Encoded Fluorogenic Allosteric Aptamer.

Imaging and tracking tools for natural cellular RNA with improved biocompatibility, specificity, and sensitivity are critical to understanding RNA function and providing insights into disease therapeutics. We developed a new genetically encoded sensor using fluorogenic allosteric aptamer (FaApt) for the sensitive imaging of the localization and dynamics of RNA targets in live cells. Target RNAs can be specifically recognized with our sensor by forming perfectly complementary duplexes, which in turn can induce allosteric structural changes of the sensor to refold the native conformation of fluorogenic RNA aptamers. We demonstrated the ability of the sensor to monitor the effect of tumor necrosis factor and small-molecule inhibitor on the expression abundance of CXCL1 and survivin mRNA in human cancer cells, respectively. The asymmetrical distribution of endogenous Squint mRNA was confirmed in developing zebrafish embryos through microinjection of FaApt probes. This study provides an effective molecular tool for sensitive imaging and tracking endogenous RNA in living cells. Due to the high specificity and small size of our sensor system, it is expected to be applied to early diagnosis of RNA marker-related diseases and real-time evaluation of the treatment process.

Pt(IV) Prodrug as a Potential Antitumor Agent with APE1 Inhibitory Activity.

The base excision repair (BER) pathway is essential for cancer cells to resist chemotherapeutic treatment, but its significance is underrated. The present study describes a novel Pt(IV) prodrug, AP1, targeting a critical BER protein, apurinic/apyrimidinic endonuclease 1 (APE1). AP1 induces intracellular accumulation of platinum and activates DNA damage response and apoptosis signals. AP1 can strongly inhibit the growth of malignant cells, including cisplatin-resistant cancer cells, with up to 18.11 times inhibition compared with cisplatin. Moreover, it is as toxic to normal cells as cisplatin. In a xenograft model, AP1 is 3.86-fold more potent than cisplatin without adverse effects. Intriguingly, AP1 can directly inhibit the AP endonuclease activity of APE1, leading to an interruption of miRNA processing and upregulation of the tumor suppressor PTEN. Our findings shed light on a mode of Pt(IV) interaction with a target protein and highlight the critical role of BER in platinum-based cancer treatment.

Preparation and Application of α-Imino Ketones through One-Pot Tandem Reactions Based on Heyns Rearrangement.

α-Imino ketone is a useful building block for the preparation of α-amino ketones and α-amino alcohols. However, its preparation has been seldomly seen. Herein, a metal-free and operationally simple strategy has been developed to generate α-imino ketones with high regioselectivity. Meanwhile, the method allowed for the preparation of various N,O-ketals with high regioselectivities and diastereoselectivities through cascade reactions in one pot.

An organocatalytic asymmetric Friedel-Crafts reaction of 2-substituted indoles with aldehydes: enantioselective synthesis of α-hydroxyl ketones by low loading of chiral phosphoric acid.

Hydroxyl alkylation of indoles by Friedel-Crafts reaction with a carbonyl compound is a useful strategy. However, the reaction was restricted to ketones due to the easy formation of a bisindole byproduct. Therefore, hydroxyl alkylation of an aldehyde with indole is confronted with great challenges. Here, we report an efficient strategy for asymmetric hydroxyl alkylation of 2-substituted indoles with aldehydes under 0.1 mol% chiral phosphoric acid. A series of α-hydroxyl ketones were obtained in high yields (up to 99%) and good enantioselectivities (up to 97%).