An Asymmetry in Monolayer Tension Regulates Lipid Droplet Budding Direction
An Asymmetry in Monolayer Tension Regulates Lipid Droplet Budding Direction
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DOI：
10.1016/j.bpj.2017.12.014
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发表时间：
2018-02-06
影响因子：
3.4
通讯作者：
Thiam, Abdou Rachid
中科院分区：
文献类型：
--
作者：
Chorlay, Aymeric;Thiam, Abdou Rachid
细胞以中性脂质的形式储存多余的能量，中性脂质被合成并包裹在内质网单层间空间中。脂质接着分层形成脂滴（LD），令人惊讶的是，脂滴主要向胞质溶胶出芽。这种定向LD形成对能量代谢至关重要，但其机制仍知之甚少。在这里，我们重建的LD形成拓扑结构嵌入人工LD到双层囊泡的单层间空间。我们提供的实验证据表明，液滴在膜中的行为是概括的三相润湿系统的物理，由表面张力的平衡。因此，我们确定膜单层之间的轻微张力不对称调节液滴出芽侧。形成LD周围的脂质或蛋白质组成的差异调节可以产生单层张力不对称性，这将决定LD出芽侧。据我们所知，我们的研究结果提供了新的见解，蛋白质如何可能调节LD形成侧产生单层张力不对称。
Cells store excess energy in the form of neutral lipids that are synthesized and encapsulated within the endoplasmic reticulum intermonolayer space. The lipids next demix to form lipid droplets (LDs), which, surprisingly, bud off mostly toward the cytosol. This directional LD formation is critical to energy metabolism, but its mechanism remains poorly understood. Here, we reconstituted the LD formation topology by embedding artificial LDs into the intermonolayer space of bilayer vesicles. We provide experimental evidence that the droplet behavior in the membrane is recapitulated by the physics of three-phase wetting systems, dictated by the equilibrium of surface tensions. We thereupon determined that slight tension asymmetries between the membrane monolayers regulate the droplet budding side. A differential regulation of lipid or protein composition around a forming LD can generate amonolayer tension asymmetry that will determine the LD budding side. Our results offer, to our knowledge, new insights on how the proteins might regulate LD formation side by generating a monolayer tension asymmetry.