Lipid droplets (LDs) are multi-functional cellular organelles that store energy, and regulate many aspects of cell physiology. However, our understanding of the biogenesis of LDs remains very limited. Originating from the endoplasmic reticulum (ER), LDs are highly unique organelles in that each LD is bounded by a monolayer of amphipathic lipids. Recent progress has unveiled critical roles of non-bilayer lipids in LD formation. For instance, non-bilayer lipids such as lysophospholipids, diacylglycerol and phosphatidic acid (PA) can impact the curvature, surface and line tension of the ER, thereby impacting LD biogenesis. Two well-known regulators of LD formation, FIT2/FITM2 and seipin, have both been implicated in controlling the metabolism and/or distribution of non-bilayer lipids. We summarize and integrate these recent advances and propose that non-bilayer lipids may play a critical role in each step of LD biogenesis.

脂质滴（LDs）是多功能的细胞器，可储存能量并调节细胞生理学的许多方面。但是，我们对LDs的生物发生的理解仍然非常有限。LD源自内质网（ER），是高度独特的细胞器，因为每个LD都被两亲性脂质的单层结合。最近的进展揭示了非双层脂质在LD形成中的关键作用。例如，非双层脂质，例如溶血磷脂，二酰基甘油和磷脂酸（PA）可以影响ER的曲率，表面和线张力，从而影响LD的生物发生。LD形成的两个众所周知的调节剂FIT2 / FITM2和seipin都与控制非双层脂质的代谢和/或分布有关。