Involvement of STI1 protein in the differentiation process of Trypanosoma cruzi

• Published in: Parasitology international 2018-04, Vol.67 (2), p.131-139
• Main Authors: Schmidt, Juliana C., Manhães, Lauro, Fragoso, Stenio P., Pavoni, Daniela P., Krieger, Marco A.
• Format: Article
• Language: English
• Subjects: Differentiation; Fluorescent Antibody Technique, Indirect; Gene Knockout Techniques; Gene Silencing; Heat-Shock Proteins - genetics; Heat-Shock Proteins - metabolism; Hop; Life Cycle Stages - genetics; Life Cycle Stages - physiology; Metacyclogenesis; Mutation; Protozoan Proteins - genetics; Protozoan Proteins - metabolism; STI1; Stress, Physiological; Trypanosoma cruzi; Trypanosoma cruzi - chemistry; Trypanosoma cruzi - growth & development; Trypanosoma cruzi - physiology; Trypanosoma cruzi - ultrastructure
• ISSN: 1383-5769; 1873-0329
• DOI: 10.1016/j.parint.2017.10.009

The protozoan Trypanosoma cruzi is a parasite exposed to several environmental stressors inside its invertebrate and vertebrate hosts. Although stress conditions are involved in its differentiation processes, little information is available about the stress response proteins engaged in these activities. This work reports the first known association of the stress-inducible protein 1 (STI1) with the cellular differentiation process in a unicellular eukaryote. Albeit STI1 expression is constitutive in epimastigotes and metacyclic trypomastigotes, higher protein levels were observed in late growth phase epimastigotes subjected to nutritional stress. Analysis by indirect immunofluorescence revealed that T. cruzi STI1 (TcSTI1) is located throughout the cell cytoplasm, with some cytoplasmic granules appearing in greater numbers in late growing epimastigotes and late growing epimastigotes subjected to nutritional stress. We observed that part of the fluorescence signal from both TcSTI1 and TcHSP70 colocalized around the nucleus. Gene silencing of sti1 in Trypanosoma brucei did not affect cell growth. Similarly, the growth of T. cruzi mutant parasites with a single allele sti1 gene knockout was not affected. However, the differentiation of epimastigotes in metacyclic trypomastigotes (metacyclogenesis) was compromised. Lower production rates and numbers of metacyclic trypomastigotes were obtained from the mutant parasites compared with the wild-type parasites. These data indicate that reduced levels of TcSTI1 decrease the rate of in vitro metacyclogenesis, suggesting that this protein may participate in the differentiation process of T. cruzi. [Display omitted] •STI1 colocalizes with HSP70 in some cytoplasmic granules.•Cell growth is not affected by blocking STI1 expression in T. brucei.•Inactivation of one copy of the sti1 gene in T. cruzi does not affect cell grow.•STI1 appears to have a role in T. cruzi differentiation to infective forms.