Liu Shu-Lin, Sheng Ren, Jung Jae Hun, Wang Li, Stec Ewa, O'Connor Matthew J, Song Seohyoen, Bikkavilli Rama Kamesh, Winn Robert A, Lee Daesung, Baek Kwanghee, Ueda Kazumitsu, Levitan Irena, Kim Kwang-Pyo, Cho Wonhwa
Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois, USA.
Department of Applied Chemistry, Kyung Hee University, Yongin, Korea.
Nat Chem Biol. 2017 Mar;13(3):268-274. doi: 10.1038/nchembio.2268. Epub 2016 Dec 26.
Controlled distribution of lipids across various cell membranes is crucial for cell homeostasis and regulation. We developed an imaging method that allows simultaneous in situ quantification of cholesterol in two leaflets of the plasma membrane (PM) using tunable orthogonal cholesterol sensors. Our imaging revealed marked transbilayer asymmetry of PM cholesterol (TAPMC) in various mammalian cells, with the concentration in the inner leaflet (IPM) being ∼12-fold lower than that in the outer leaflet (OPM). The asymmetry was maintained by active transport of cholesterol from IPM to OPM and its chemical retention at OPM. Furthermore, the increase in the IPM cholesterol level was triggered in a stimulus-specific manner, allowing cholesterol to serve as a signaling lipid. We found excellent correlation between the IPM cholesterol level and cellular Wnt signaling activity, suggesting that TAPMC and stimulus-induced PM cholesterol redistribution are crucial for tight regulation of cellular processes under physiological conditions.
脂质在各种细胞膜之间的可控分布对于细胞稳态和调节至关重要。我们开发了一种成像方法，该方法使用可调谐正交胆固醇传感器能够同时原位定量质膜（PM）两个小叶中的胆固醇。我们的成像显示，在各种哺乳动物细胞中质膜胆固醇（TAPMC）存在明显的跨膜不对称性，内小叶（IPM）中的浓度比外小叶（OPM）中的浓度低约12倍。这种不对称性通过胆固醇从IPM到OPM的主动转运及其在OPM处的化学滞留得以维持。此外，IPM胆固醇水平的升高以刺激特异性方式触发，使胆固醇能够作为信号脂质。我们发现IPM胆固醇水平与细胞Wnt信号传导活性之间具有良好的相关性，这表明TAPMC和刺激诱导的质膜胆固醇重新分布对于生理条件下细胞过程的严格调节至关重要。
