Cell Biology

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Science  17 Apr 2009:
Vol. 324, Issue 5925, pp. 315
DOI: 10.1126/science.324.5925.315d

Cells stockpile nutrients and metabolites in storage compartments that can be raided when environmental conditions change. Lipid droplets are dynamic cellular caches of neutral lipids, such as triacylglycerol, which can be used as high-energy reserves, signaling molecules, and membrane building blocks. On the other hand, lipid droplets have been implicated in devastating metabolic diseases, such as diabetes and atherosclerosis, and are found in almost all cells from yeast to mammals. Nevertheless, relatively little is known about how they are formed.

Eastman et al. have established that the protein SPG20 (also known as spartin) regulates lipid droplet formation. Using cultured human cells, they found that SPG20 localized to lipid droplets and interacted with the lipid droplet-associated protein TIP47. SPG20 localization was regulated by WWP1, a member of the HECT-ubiquitin ligase family that modulates diverse cellular functions by tagging proteins with ubiquitin. Further, mutations in SPG20 have been linked to the rare neurological disease Troyer syndrome, which is characterized by muscle spasticity and limb paralysis; a disease-associated SPG20 mutant did not localize to lipid droplets. — HP*

J. Cell Biol. 184, 881 (2009).

  • *Helen Pickersgill is a locum editor in Science's editorial department.

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