Disturbed cholesterol traffic but normal proteolytic function in LAMP-1/LAMP-2 double-deficient fibroblasts

Eeva Liisa Eskelinen, Christine Katrin Schmidt, Silja Neu, Marion Willenborg, Graciela Fuertes, Natalia Salvador, Yoshitaka Tanaka, Renate Lüllmann-Rauch, Dieter Hartmann, Jörg Heeren, Kurt Von Figura, Erwin Knecht, Paul Saftig

Research output: Contribution to journalArticlepeer-review

184 Citations (Scopus)

Abstract

Mice double deficient in LAMP-1 and -2 were generated. The embryos died between embryonic days 14.5 and 16.5. An accumulation of autophagic vacuoles was detected in many tissues including endothelial cells and Schwann cells. Fibroblast cell lines derived from the double-deficient embryos accumulated autophagic vacuoles and the autophagy protein LC3II after amino acid starvation. Lysosomal vesicles were larger and more peripherally distributed and showed a lower specific density in Percoll gradients in double deficient when compared with control cells. Lysosomal enzyme activities, cathepsin D processing and mannose-6-phosphate receptor expression levels were not affected by the deficiency of both LAMPs Surprisingly, LAMP-1 and -2 deficiencies did not affect long-lived protein degradation rates, including proteolysis due to chaperone-mediated autophagy. The LAMP-1/2 double-deficient cells and, to a lesser extent, LAMP-2 single-deficient cells showed an accumulation of unesterified cholesterol in endo/lysosomal, rab7, and NPC1 positive compartments as well as reduced amounts of lipid droplets. The cholesterol accumulation in LAMP-1/2 double-deficient cells could be rescued by overexpression of murine LAMP-2a, but not by LAMP-1, highlighting the more prominent role of LAMP-2. Taken together these findings indicate partially overlapping functions for LAMP-1 and -2 in lysosome biogenesis, autophagy, and cholesterol homeostasis.

Original languageEnglish
Pages (from-to)3132-3145
Number of pages14
JournalMolecular biology of the cell
Volume15
Issue number7
DOIs
Publication statusPublished - Jul 2004

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

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