Lipid droplets on the move: remodeling, trafficking, and interaction with other organelles

Lipid droplets (LDs) are subcellular organelles consisting of a neutral lipid core surrounded by a monolayered membrane and a protein coat. Recent literature suggests that LDs play a central role in carbon and energy homeostasis, which is particularly important for adapting to a fluctuating environment or changing metabolic status. This is achieved partly thanks to: (i) the large repertoire of proteins associated with LDs; (ii) the ability of LDs to modulate their size, as well as their protein and lipid constituents; (iii) the mobility of LDs, which act as carriers for the transport of cellular materials; and (iv) the dynamic nature of LDs in connecting to or disconnecting from other organelles (e.g. peroxisomes, mitochondria, or autophagosomes) in response to cellular needs. Here, we first provide a comparative overview of LD biogenesis and turnover in mammalian, yeast, and photosynthetic organisms (plants and microalgae). We focus particularly on how cells regulate the size and composition of LD proteins and lipids in response to metabolic and environmental cues, and how LDs are mobilized and trafficked within the cell.