The lipid droplet (LD) is a dynamic organelle responsible for lipid storage and metabolism that plays important roles in maintaining lipid homeostasis. However, limited strategies are available for tracking the LD content exchange. In this contribution, we report a novel fluorescent probe, TPE-AmAl, for real-time LD content dynamics tracking. TPE-AmAl is LD-specific, but emits faintly due to its intramolecular motion. Upon photoactivation, it undergoes a photocyclodehydrogenation reaction and shows a large fluorescence increment. Thus, it can be used for highlighting selected LDs with high spatial resolution. By measuring the fluorescence changes in the distal region, the lipid content exchange efficiency can be estimated. In our experiment, LD content exchange rate differences between nascent and mature LDs as well as cells with normal and deficient LD budding machinery are observed. This probe expands the fluorescence-based toolbox for LD content dynamics studies.

脂滴 (LD) 是负责脂质储存和代谢的动态细胞器，在维持脂质稳态方面起着重要作用。但是，可用于跟踪 LD 内容交换的策略有限。在这篇文章中，我们报告了一种新型荧光探针 TPE-AmAl，用于实时 LD 含量动态跟踪。TPE-AmAl 是 LD 特异性的，但由于其分子内运动而发出微弱的光。光活化后，它会发生光环化脱氢反应并显示出较大的荧光增量。因此，它可用于突出显示具有高空间分辨率的选定 LD。通过测量远端区域的荧光变化，可以估计脂质含量交换效率。在我们的实验中，观察到新生和成熟 LD 以及具有正常和缺陷 LD 出芽机制的细胞之间的 LD 含量交换率差异。该探针扩展了用于 LD 含量动态研究的基于荧光的工具箱。