Role of acidic compartments in Trypanosoma brucei, with special reference to low-density lipoprotein processing

Isabelle Coppens, Pierre Baudhuin, Fred R. Opperdoes, Pierre J. Courtoy

Research output: Contribution to journalArticle

Abstract

In the bloodstream form of Trypanosoma brucei, specific receptors mediate the endocytosis of host low-density lipoprotein particles. We have explored the fate of ligand and receptor with a biochemical approach, using inhibitors of the endocytotic apparatus. The weak base chloroquine rapidly accumulates in trypanosomes, its uptake is prevented by the proton ionophore monensin, and it induces the swelling of intracellular vacuoles, indicating that their content is acidic. Cell-associated LDL is rapidly degraded into intermediately sized fragments and TCA-soluble material that can be recovered in cell extracts and extracellular medium. Chloroquine, leupeptin and E64, but not PMSF, efficiently prevent LDL proteolysis, suggesting that degradation occurs in those acidic compartment(s) and is mediated by thiol-protease(s). Both monensin and chloroquine decrease the number of LDL receptors exposed at the cell surface, a phenomenon amplified in the presence of LDL. This provides indirect evidence that internalised LDL receptors are recycled at a rate which is slowed down by receptor occupancy and by agents that impair acidification of the endocytic organelles. Finally, chloroquine decreases by half the growth rate of procyclic trypanosomes in vitro at 5 μg ml-1. At 40 mg kg-1 per day, it also slows down the increase in parasitaemia and prolongs the survival time of infected mice by up to 2 days.

Original languageEnglish (US)
Pages (from-to)223-232
Number of pages10
JournalMolecular and Biochemical Parasitology
Volume58
Issue number2
DOIs
StatePublished - Apr 1993
Externally publishedYes

Keywords

  • Chloroquine
  • Endocytosis
  • LDL proteolysis
  • LDL receptor recycling
  • Monensin
  • Trypanosoma brucei

ASJC Scopus subject areas

  • Parasitology
  • Molecular Biology

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