School of Chemistry and Food Engineering , Changsha University of Science and Technology , Changsha 410114 , P.R. China.
College of Chemistry and Environmental Engineering , Shanxi Datong University , Datong , Shanxi 037009 , P.R. China.
Anal Chem. 2019 Jul 2;91(13):8574-8581. doi: 10.1021/acs.analchem.9b01861. Epub 2019 Jun 19.
Mitophagy, as an evolutionarily conserved cellular process, plays a crucial role in preserving cellular metabolism and physiology. Various microenvironment alterations assigned to mitophagy including pH, polarity, and deregulated biomarkers are increasingly understood. However, mitophagy-specific viscosity dynamic in live cells remains a mystery and needs to be explored. Here, a water-soluble mitochondria-targetable molecular rotor, ethyl-4-[3,6-bis(1-methyl-4-vinylpyridium iodine)-9 H-carbazol-9-yl)] butanoate (BMVC), was exploited as a fluorescent viscosimeter for imaging viscosity variation during mitophagy. This probe contains two positively charged 1-methyl-4-vinylpyridium components as the rotors, whose rotation will be hindered with the increase of environmental viscosity, resulting in enhancement of fluorescence emission. The results demonstrated that this probe operates well in a mitochondrial microenvironment and displays an off-on fluorescence response to viscosity. By virtue of this probe, new discoveries such as the mitochondrial viscosity will increase during mitophagy are elaborated. The real-time visualization of the mitophagy process under nutrient starvation conditions was also proposed and actualized. We expect this probe would be a robust tool in the pathogenic mechanism research of mitochondrial diseases.
自噬作为一种进化上保守的细胞过程，对于维持细胞代谢和生理功能至关重要。越来越多的人了解到，包括 pH 值、极性和失调生物标志物在内的各种微环境变化与自噬有关。然而，活细胞中自噬特异性粘度动态仍然是一个谜，需要进一步探索。在这里，我们利用一种水溶性线粒体靶向分子转子，乙基-4-[3,6-双(1-甲基-4-乙烯基吡啶碘)-9H-咔唑-9-基)]丁酸盐（BMVC），作为荧光粘度计来成像自噬过程中的粘度变化。该探针包含两个作为转子的正电荷 1-甲基-4-乙烯基吡啶部分，其旋转会随着环境粘度的增加而受阻，导致荧光发射增强。结果表明，该探针在线粒体微环境中运行良好，并对粘度表现出关-开荧光响应。借助该探针，阐述了自噬过程中线粒体粘度增加等新发现。还提出并实现了在营养饥饿条件下实时可视化自噬过程。我们期望该探针将成为线粒体疾病发病机制研究的有力工具。
