当前位置:首页 / 科学研究 / 实验室 / 正文

实验室

10:30-11:30, Wednesday, August 8, 2018


Speaker: Qiang Li (李强), Ph.D.

Research Associate

Laboratory of Chemical Biology and Microbial Pathogenesis

The Rockefeller University

Topic:  Chemical Biology Studies of Anti-inflammatory Lipids

Host:   Chao Li, Ph.D.

Abstract

A number of endogenous polyunsaturated fatty acids (PUFAs), including lipoxins, resolvins and protectins can help resolve inflammation and prevent various diseases. The beneficial effects in human health of these anti-inflammatory lipids have long been recognized, but their mechanism(s) of action and precise protein targets have remained unclear. Peroxisome proliferator-activated receptor γ (PPARγ) which is a ligand activated transcription factor and has been proposed to sense unsaturated and oxidized fatty acids may serve as a candidate target of these anti-inflammatory lipids. To address these questions, I have completed the total synthesis of anti-inflammatory lipid protectin D1 (PD1) by utilizing a convergent strategy. PPARγ-transactivation assay indicates that our synthetic PD1 potently activates PPARγ. I also evaluated the biochemical interactions of PD1 with PPARγ in cells using competitive photoaffinity labeling with a bifunctional fatty acid reporter (x-alk-16). Notably, over-expressed PPARγ can be crosslinked by x-alk-16 in a UV- and dose-dependent manner both in vitro and in mammalian cells. To further expand its application for endogenous PPARγ, I evaluated A549 cells and HT-29 cells, which also showed excellent x-alk-16 crosslinking of endogenous PPARγ both in vitro and in mammalian cells. These findings indicate that x-alk-16 can serve as a suitable photoaffinity fatty acid reporter to study PPARγ. By utilizing this chemical tool, the interaction of any bioactive small molecules with PPARγ can be evaluated. Several PPARγ synthetic ligands, including nTZDpa and rosiglitazone are chosen as a showcase for this study because they show very high affinity to PPARγ. These PPARγ synthetic ligands can compete the interaction between x-alk-16 and PPARγ. When applying PD1 as competitor, obvious competition effect can be observed, which suggest that PPARγ is one of the major protein targets of PD1. By performing unbiased chemical proteomic analysis, several unpredicted protein targets of PD1 were also identified and are currently being evaluated. Our findings should improve the current understanding of anti-inflammatory lipids targets and help elucidate the key pathways to improve the resolution of inflammation.