lipid droplet fusion

Definition

Target type: biologicalprocess

The process by which a single lipid droplet is created from the fusion of two or more lipid droplets. [PMID:34508658, PMID:36477540]

Lipid droplet fusion is a critical process in cellular lipid metabolism, enabling the merging of individual lipid droplets into larger structures. This process plays a crucial role in regulating the storage, mobilization, and utilization of lipids. The fusion event is facilitated by a complex interplay of proteins, including perilipin, adipose triglyceride lipase (ATGL), and the GTPase Rab18. These proteins localize to the surface of lipid droplets and orchestrate the fusion process through a series of steps.

1. **Recruitment and Activation of Fusion Machinery:** Perilipin, a protein that coats the surface of lipid droplets, plays a critical role in initiating fusion by recruiting other proteins essential for the process. ATGL, a lipase enzyme, is also recruited to the surface of lipid droplets, where it hydrolyzes triglycerides, releasing free fatty acids that can be used for energy production. Rab18, a small GTPase protein, is involved in the regulation of vesicle trafficking and is also recruited to the surface of lipid droplets.

2. **Lipid Droplet Tethering:** Once the necessary proteins are recruited, the lipid droplets begin to tether together. This tethering is thought to be mediated by interactions between the proteins on the surface of the droplets.

3. **Membrane Fusion:** The tethered lipid droplets then undergo membrane fusion. This step involves the merging of the phospholipid bilayers of the two droplets, resulting in a single, larger droplet.

4. **Content Mixing:** The final stage of lipid droplet fusion involves the mixing of the contents of the two droplets. This includes the triglycerides, cholesterol esters, and other lipids that are stored within the droplets.

The fusion of lipid droplets is a highly regulated process that is influenced by a variety of factors, including nutritional status, hormonal signals, and cellular stress. For instance, during periods of nutrient deprivation, lipid droplets fuse to increase the efficiency of lipolysis, the breakdown of triglycerides into free fatty acids that can be used for energy production. Conversely, during periods of nutrient abundance, lipid droplets fuse to store excess lipids in a more efficient manner.

In summary, lipid droplet fusion is a complex process that is essential for maintaining lipid homeostasis. It is tightly regulated by a variety of cellular mechanisms and plays a critical role in the storage, mobilization, and utilization of lipids.'
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Proteins (1)

Compounds (1)