Lipid droplets interact with mitochondria using SNAP23.
Triglyceride-containing lipid droplets (LD) are dynamic organelles stored on demand in all cells. These droplets grow through a fusion process mediated by SNARE proteins, including SNAP23. The droplets have also been shown to be highly motile and interact with other cell organelles, including peroxisomes and the endoplasmic reticulum. We have used electron and confocal microscopy to demonstrate that LD form complexes with mitochondria in NIH 3T3 fibroblasts. Using an in vitro system of purified LD and mitochondria, we also show the formation of the LD-mitochondria complex, in which cytosolic factors are involved. Moreover, the presence of LD markers in mitochondria isolated by subcellular fractionations is demonstrated. Finally, ablation of SNAP23 using siRNA reduced complex formation and beta oxidation, which suggests that the LD-mitochondria complex is functional in the cell.
Jägerström
Sara
S
Sahlgrenska Center for Cardiovascular and Metabolic Research, Wallenberg Laboratory, Lab 1, Bruna Stråket 16, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden.
Polesie
Sam
S
Wickström
Ylva
Y
Johansson
Bengt R
BR
Schröder
Henrik D
HD
Højlund
Kurt
K
Boström
Pontus
P
D000818:Animals; D055785:Gene Knockdown Techniques; D008565:Membrane Proteins / Q000819:agonists / Q000378:metabolism*; D051379:Mice; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D041681:NIH 3T3 Cells; D019301:Oleic Acid / Q000494:pharmacology; D010084:Oxidation-Reduction; D000070780:Perilipin-2; D000091402:Prohibitins; D050766:Qb-SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D050767:Qc-SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D012097:Repressor Proteins / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism*
D008565:Membrane Proteins; D000070780:Perilipin-2; D000091402:Prohibitins; D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; D034741:RNA, Small Interfering; D012097:Repressor Proteins; C107017:Snap23 protein, mouse; D014280:Triglycerides; D019301:Oleic Acid