INGEBI   02650
INSTITUTO DE INVESTIGACIONES EN INGENIERIA GENETICA Y BIOLOGIA MOLECULAR "DR. HECTOR N TORRES"
Unidad Ejecutora - UE
artículos
Título:
A T. cruzi phosphatidylinositol 3-kinase (TcVps34) is involved in osmoregulation and receptor-mediated endocytosis.
Autor/es:
SCHOIJET, A.C.; MIRANDA, K.; GIRARD-DIAS W.; DE SOUZA, W.; FLAWIÁ, M.M.; TORRES, H.N.; DOCAMPO, R.; ALONSO, G.D.
Revista:
JOURNAL OF BIOLOGICAL CHEMISTRY
Editorial:
American Society for Bochemistry and Molecular Biology
Referencias:
Año: 2008 vol. 283 p. 31541 - 31550
ISSN:
0021-9258
Resumen:
Trypanosoma cruzi, the etiological agent of Chagas’ disease, has the ability to respond to a variety of environmental changes during its life cycle both in the insect vector and in the vertebrate host. Since regulation of transcription initiation seems to be nonfunctional in this parasite, it is important to investigate other regulatory mechanisms of adaptation. Regulatory mechanisms at the level of signal transduction pathways involving phosphoinositides are good candidates for this purpose. Here we report the identification of the first phosphatidylinositol 3-kinase (PI3K) in T. cruzi, with similarity with its yeast counterpart, Vps34p. TcVps34 specifically phosphorylates phosphatidylinositol to produce phosphatidylinositol 3-phosphate, thus confirming that it belongs to class III PI3K family. Overexpression of TcVps34 resulted in morphological and functional alterations related to vesicular trafficking. While inhibition of TcVps34 with specific PI3K inhibitors, such as wortmannin and LY294,000, resulted in reduced regulatory volume decrease after hyposmotic stress, cells overexpressing this enzyme were resistant to these inhibitors. Furthermore, these cells were able to recover their original volume faster than wild type cells when they were submitted to severe hyposmotic stress. In addition, in TcVps34-overexpressing cells the activities of vacuolar-H+-ATPase and vacuolar H+-pyrophosphatase were altered, suggesting defects in the acidification of intracellular compartments. Furthermore, receptor-mediated endocytosis was partially blocked whereas fluid phase endocytosis was not affected, confirming a function for TcVps34 in membrane trafficking. Taken together, these results strongly support that TcVps34 plays a prominent role in vital processes for T. cruzi survival such as osmoregulation, acidification and vesicular trafficking.