Evidence for the Involvement of annexin 6 in the trafficking between the endocytic compartment and lysosomes

Exp Cell Res. 2001 Sep 10;269(1):13-22. doi: 10.1006/excr.2001.5268.

Abstract

Annexins are a family of calcium-dependent phospholipid-binding proteins, which have been implicated in a variety of biological processes including membrane trafficking. The annexin 6/lgp120 prelysosomal compartment of NRK cells was loaded with low-density lipoprotein (LDL) and then its transport from this endocytic compartment and its degradation in lysosomes were studied. NRK cells were microinjected with the mutated annexin 6 (anx6(1-175)), to assess the possible involvement of annexin 6 in the transport of LDL from the prelysosomal compartment. The results indicated that microinjection of mutated annexin 6, in NRK cells, showed the accumulation of LDL in larger endocytic structures, denoting retention of LDL in the prelysosomal compartment. To confirm the involvement of annexin 6 in the trafficking and the degradation of LDL we used CHO cells transfected with mutated annexin 6(1-175). Thus, in agreement with NRK cells the results obtained in CHO cells demonstrated a significant inhibition of LDL degradation in CHO cells expressing the mutated form of annexin 6 compared to controls overexpressing wild-type annexin 6. Therefore, we conclude that annexin 6 is involved in the trafficking events leading to LDL degradation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Annexin A6 / genetics
  • Annexin A6 / metabolism*
  • Annexin A6 / pharmacology
  • CHO Cells / drug effects
  • CHO Cells / metabolism
  • CHO Cells / ultrastructure
  • Calpain / metabolism
  • Carbocyanines / pharmacokinetics
  • Cell Compartmentation / drug effects
  • Cell Compartmentation / physiology*
  • Cricetinae
  • Endocytosis / drug effects
  • Endocytosis / physiology*
  • Fluorescent Antibody Technique
  • Fluorescent Dyes / pharmacokinetics
  • Genetic Vectors
  • Iodine Radioisotopes / pharmacology
  • Leupeptins / pharmacology
  • Lipoproteins, LDL / drug effects
  • Lipoproteins, LDL / metabolism
  • Lysosomes / drug effects
  • Lysosomes / metabolism*
  • Protein Transport / drug effects
  • Protein Transport / physiology*
  • Spectrin / metabolism
  • Subcellular Fractions / metabolism
  • Transport Vesicles / drug effects
  • Transport Vesicles / metabolism*

Substances

  • 3,3'-dihexadecylindocarbocyanine
  • Annexin A6
  • Carbocyanines
  • Fluorescent Dyes
  • Iodine Radioisotopes
  • Leupeptins
  • Lipoproteins, LDL
  • acetylleucyl-leucyl-norleucinal
  • Spectrin
  • Calpain