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Isolation of Cellular Lipid Droplets: Two Purification Techniques Starting from Yeast Cells and Human Placentas
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Isolation of Cellular Lipid Droplets: Two Purification Techniques Starting from Yeast Cells and Human Placentas

Published on: April 1, 2014

TIP47 functions in the biogenesis of lipid droplets

Anna V Bulankina1, Anke Deggerich, Dirk Wenzel

  • 1Institute for Biochemistry II, University of Göttingen, 37073 Göttingen, Germany.

The Journal of Cell Biology
|May 20, 2009
PubMed

Insights

Tail-interacting protein of 47 kD (TIP47) does not sort mannose 6-phosphate receptors. Instead, TIP47 is crucial for lipid droplet (LD) biogenesis and maturation, reorganizing lipids to form small discs.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Lipid Metabolism

Background:

  • Tail-interacting protein of 47 kD (TIP47) was previously thought to be a cargo selection device for mannose 6-phosphate receptors (MPRs).
  • Its proposed role involved directing MPR transport from endosomes to the trans-Golgi network for lysosomal enzyme sorting.

Purpose of the Study:

  • To investigate the actual function of TIP47 in cellular transport and sorting pathways.
  • To determine the role of TIP47 in the context of lipid metabolism and organelle biogenesis.

Main Methods:

  • TIP47 knockdown experiments to assess effects on MPR distribution and lysosomal enzyme sorting.
  • Analysis of TIP47 recruitment to cellular organelles, particularly lipid droplets (LDs).
  • Biochemical assays to characterize TIP47's interaction with lipids and its effect on liposome structure.

Main Results:

  • Cytosolic TIP47 was not recruited to endosomes or the Golgi apparatus.
  • TIP47 knockdown did not impact MPR trafficking or lysosomal enzyme sorting.
  • TIP47 was identified as a lipid droplet-associated protein, recruited via its amino-terminal 11-mer repeats.
  • TIP47 demonstrated apolipoprotein-like properties, restructuring liposomes into smaller lipid discs.
  • Suppression of TIP47 impaired LD maturation and reduced triacylglycerol incorporation into LDs.

Conclusions:

  • TIP47 does not function as a sorting device for MPRs.
  • TIP47 plays a critical role in the biogenesis and maturation of lipid droplets.
  • TIP47's apolipoprotein-like activity is essential for its function in LD formation.

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