Rab32 is essential for maintaining functional acidocalcisomes, and for growth and infectivity of Trypanosoma cruzi

J Cell Sci. 2015 Jun 15;128(12):2363-73. doi: 10.1242/jcs.169466. Epub 2015 May 11.


The contractile vacuole complex (CVC) of Trypanosoma cruzi, the etiologic agent of Chagas disease, collects and expels excess water as a mechanism of regulatory volume decrease after hyposmotic stress; it also has a role in cell shrinking after hyperosmotic stress. Here, we report that, in addition to its role in osmoregulation, the CVC of T. cruzi has a role in the biogenesis of acidocalcisomes. Expression of dominant-negative mutants of the CVC-located small GTPase Rab32 (TcCLB.506289.80) results in lower numbers of less-electron-dense acidocalcisomes, lower content of polyphosphate, lower capacity for acidocalcisome acidification and Ca(2+) uptake that is driven by the vacuolar proton pyrophosphatase and the Ca(2+)-ATPase, respectively, as well as less-infective parasites, revealing the role of this organelle in parasite infectivity. By using fluorescence, electron microscopy and electron tomography analyses, we provide further evidence of the active contact of acidocalcisomes with the CVC, indicating an active exchange of proteins between the two organelles.

Keywords: Acidocalcisome; Calcium; Contractile vacuole; Polyphosphate; Vacuolar pyrophosphatase.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acids / metabolism*
  • Animals
  • Blotting, Western
  • Calcium / metabolism*
  • Cells, Cultured
  • Chagas Disease / parasitology*
  • Chlorocebus aethiops
  • Fibroblasts / cytology
  • Fibroblasts / parasitology
  • Fluorescent Antibody Technique
  • Foreskin / cytology
  • Humans
  • Immunoenzyme Techniques
  • Male
  • Microscopy, Electron
  • Myoblasts / cytology
  • Myoblasts / parasitology
  • Organelles / metabolism*
  • Osmoregulation / physiology
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism*
  • RNA, Messenger / genetics
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • Trypanosoma cruzi / pathogenicity*
  • Vacuoles / metabolism
  • Vero Cells
  • Water-Electrolyte Balance


  • Acids
  • Protozoan Proteins
  • RNA, Messenger
  • Calcium