Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China.
Soft Matter. 2023 Oct 11;19(39):7494-7501. doi: 10.1039/d3sm00728f.
Lipid droplets (LDs) are intracellular organelles that play a central role in cellular lipid balance and energy homeostasis. Though extensive experimental studies have been carried out on LD biogenesis, relatively little is known about the mechanical interaction between LDs and vesicles, and in particular effects of area difference between vesicle leaflets on LD evolution are not theoretically rationalized. Here we theoretically explore how the monolayer area difference regulates the budding and morphological evolution of an LD embedded in the vesicle membrane. It is shown that both the monolayer area difference and interfacial energy strength, attributed to the LD-membrane contact, facilitate the LD budding with the confined LD evolving from a bulge to a spherical protrusion. The budding direction is towards the monolayer with more phospholipids. Outward and inward budding phase diagrams are established with respect to the interfacial energy strength and area ratio between the outer and inner monolayers. Moreover, the osmotic pressure of the vesicle promotes the LD budding at a small monolayer area difference and inhibits the budding at a relatively large monolayer area difference.
脂滴（LDs）是细胞内的细胞器，在细胞脂质平衡和能量稳态中起着核心作用。尽管对 LD 的生物发生进行了广泛的实验研究，但对于 LDs 和囊泡之间的机械相互作用知之甚少，特别是关于囊泡小叶之间的面积差异对 LD 演化的影响在理论上还没有得到合理的解释。在这里，我们从理论上探讨了单层面积差异如何调节嵌入在囊泡膜中的 LD 的出芽和形态演变。结果表明，单层面积差异和界面能强度（归因于 LD-膜接触）都有利于 LD 的出芽，受限制的 LD 从鼓出物演变为球形突起。出芽的方向是朝向具有更多磷脂的单层。建立了关于界面能强度和内外单层之间的面积比的向外和向内出芽相图。此外，囊泡的渗透压促进了在小单层面积差异下的 LD 出芽，而在相对大的单层面积差异下抑制了出芽。
