Cell Biology

From Fat to Fusion

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Science  09 Nov 2007:
Vol. 318, Issue 5852, pp. 888-889
DOI: 10.1126/science.318.5852.888d

In diabetes, lipid droplets can often be seen to accumulate in muscle and liver cells. The extent to which individual lipid droplets interact within the cell is not very well understood. Boström et al. describe how such intracellular lipid droplets can grow within a cell by the fusion of individual droplets; this merging is promoted by components of the intracellular vesicle fusion machinery, which are better known as the molecular mediators of transport vesicle fusion with their target membranes. Lipid droplets from fibroblast cells in culture were isolated by cell fractionation and shown to contain several proteins, including members of the so-called SNARE family of membrane fusion proteins. In an assay of lipid droplet fusion in living cells, the knockdown of lipid-droplet-associated SNAREs reduced the number of fusion events observed by up to 75%. Furthermore, in muscle cells, the co-opting of one of the SNAREs, SNAP23, to lipid droplets (for example, by adding increasing amounts of the fatty acid oleic acid) may play a role in the development of insulin resistance by diverting the SNARE from its normal function in delivering glucose transporters to the cell surface in response to insulin. — SMH

Nat. Cell Biol. 9, 1286 (2007).

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