Protein synthesis attenuation by phosphorylation of eIF2α is required for the differentiation of Trypanosoma cruzi into infective forms

• Published in: PloS one Vol. 6; no. 11; p. e27904
• Main Authors: Tonelli, Renata R, Augusto, Leonardo da Silva, Castilho, Beatriz A, Schenkman, Sergio
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 16-11-2011; Public Library of Science (PLoS)
• Subjects: Amino Acid Sequence; Amino acids; Animals; Antibodies; Biology; Blotting, Western; Cell Differentiation; Chagas disease; Chagas Disease - genetics; Chagas Disease - parasitology; Cloning; Differentiation; Digestive tract; Enzyme-Linked Immunosorbent Assay; Enzymes; Epimastigotes; Eukaryotes; Eukaryotic Initiation Factor-2 - metabolism; Exhaustion; Gastrointestinal tract; Gene expression; Immunoglobulins; Inhibition; Initiation factor eIF-2α; Insect Vectors - genetics; Insect Vectors - parasitology; Insects; Kinases; Liver - parasitology; Localization; Mammals; Medicine; Mice; Molecular Sequence Data; Nutrient deficiency; Nutrients; Parasites; Peptides; Phosphorylation; Plasmodium falciparum; Polymerase Chain Reaction; Protein Biosynthesis; Protein synthesis; Proteins; Protozoa; Protozoan Proteins - genetics; Protozoan Proteins - metabolism; Sequence Homology, Amino Acid; Signaling; Starvation; Stress; Stresses; Toxoplasma gondii; Transcription, Genetic; Translation; Translation initiation; Trypanosoma cruzi; Trypanosoma cruzi - genetics; Trypanosoma cruzi - growth & development; Trypanosoma cruzi - pathogenicity; Trypomastigotes; Vector-borne diseases; Yeast
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0027904

Chagas' disease is a potentially life-threatening illness caused by the unicellular protozoan parasite Trypanosoma cruzi. It is transmitted to humans by triatomine bugs where T. cruzi multiplies and differentiates in the digestive tract. The differentiation of proliferative and non-infective epimastigotes into infective metacyclic trypomastigotes (metacyclogenesis) can be correlated to nutrient exhaustion in the gut of the insect vector. In vitro, metacyclic-trypomastigotes can be obtained when epimastigotes are submitted to nutritional stress suggesting that metacyclogenesis is triggered by nutrient starvation. The molecular mechanism underlying such event is not understood. Here, we investigated the role of one of the key signaling responses elicited by nutritional stress in all other eukaryotes, the inhibition of translation initiation by the phosphorylation of the eukaryotic initiation factor 2α (eIF2α), during the in vitro differentiation of T. cruzi. Monospecific antibodies that recognize the phosphorylated Tc-eIF2α form were generated and used to demonstrate that parasites subjected to nutritional stress show increased levels of Tc-eIF2α phosphorylation. This was accompanied by a drastic inhibition of global translation initiation, as determined by polysomal profiles. A strain of T. cruzi overexpressing a mutant Tc-eIF2α, incapable of being phosphorylated, showed a block on translation initiation, indicating that such a nutritional stress in trypanosomatids induces the conserved translation inhibition response. In addition, Tc-eIF2α phosphorylation is critical for parasite differentiation since the overexpression of the mutant eIF2α in epimastigotes abolished metacyclogenesis. This work defines the role of eIF2α phosphorylation as a key step in T. cruzi differentiation.