Fortschritte bei aktivitätsbasierten Sonden für die isoformselektive Bildgebung enzymatischer Aktivität

Activity-based Photoacoustic Probes Reveal Elevated Intestinal MGL and FAAH Activity in a Murine Model of Obesity

Obesity is a chronic health condition characterized by the accumulation of excessive body fat which can lead to and exacerbate cardiovascular disease, type-II diabetes, high blood pressure, and cancer through systemic inflammation. Unfortunately, visualizing key mediators of the inflammatory response, such as monoacylglycerol lipase (MGL) and fatty acid amide hydrolase (FAAH), in a selective manner is a profound challenge owing to an overlapping substrate scope that involves arachidonic acid (AA). Specifically, these enzymes work in concert to generate AA, which in the context of obesity, has been implicated to control appetite and energy metabolism. In this study, we developed the first selective activity-based sensing probes to detect MGL (PA-HD-MGL) and FAAH (PA-HD-FAAH) activity via photoacoustic imaging. Activation of PA-HD-MGL and PA-HD-FAAH by their target enzymes resulted in 1.74-fold and 1.59-fold signal enhancements, respectively. Due to their exceptional selectivity profiles and deep-tissue photoacoustic imaging capabilities, these probes were employed to measure MGL and FAAH activity in a murine model of obesity. Contrary to conflicting reports suggesting levels of MGL can be attenuated or elevated, our results support the latter. Indeed, we discovered a marked increase of both targets in the gastrointestinal tract. These key findings set the stage to uncover the role of the endocannabinoid pathway in obesity-mediated inflammation.

Lessons in Organic Fluorescent Probe Discovery

Fluorescent probes have gained profound use in biotechnology, drug discovery, medical diagnostics, molecular and cell biology. The development of methods for the translation of fluorophores into fluorescent probes continues to be a robust field for medicinal chemists and chemical biologists, alike. Access to new experimental designs has enabled molecular diversification and led to the identification of new approaches to probe discovery. This review provides a synopsis of the recent lessons in modern fluorescent probe discovery.

A Molecular-Splicing Strategy for Constructing a Near-Infrared Fluorescent Probe for UDP-Glucuronosyltransferase 1A1

UDP-glucuronosyltransferase 1A1 (UGT1A1) is a vital metabolic enzyme responsible for the clearance of endogenous substances and drugs. Hitherto, the development of fluorescent probes for UGTs was severely restricted due to the poor isoform selectivity and on-off or blue-shifted fluorescence response. Herein, we established a novel "molecular-splicing" strategy to construct a highly selective near-infrared (NIR) fluorescent probe, HHC, for UGT1A1, which exhibited a NIR signal at 720 nm after UGT1A1 metabolism. HHC was then successfully used for the real-time imaging of endogenous UGT1A1 in living cells and animals and to monitor the bile excretion function. In summary, an isoform-specific NIR fluorescent probe has been developed for monitoring UGT1A1 activity in living systems, high-throughput screening of novel UGT1A1 inhibitors and visual evaluation of bile excretion function.