ABSTRACT: Trypanosoma cruzi, the causative agent of Chagas disease, undergoes several kinds of stress during its life cycle, among which is heat stress. In eukaryotes, the cellular heat stress response includes restoring protein homeostasis, reorganizing the cytoskeleton and plasma membrane, and redirecting the energy metabolism. In this work, we performed a transcriptomic analysis of the cellular response to heat shock in T. cruzi epimastigotes. Our RNA-seq results show that, in epimastigotes of both clone CL Brener and the Y strain, HSP85, HSP70, and HSP60 gene transcripts were highly abundant at normal (29 ºC) and increased temperatures (37 ºC and 40 ºC). No statistically significant variation was observed in the transcriptome at 37 ºC, whereas differentially expressed genes were observed at 40 ºC, with 1018 upregulated and 734 downregulated transcripts in CL Brener epimastigotes and 1426 upregulated and 1223 downregulated transcripts in Y strain epimastigotes. Upregulated gene transcripts were enriched in pathways related to degradation of steroids, hemoglobin, gluconate, and phosphonate and to sulfonate compound metabolism, whereas downregulated gene transcripts were also enriched in pathways related to amino acid degradation, acetyl-CoA biosynthesis, glycolysis, gluconeogenesis, pentose-phosphate pathway, nucleotide metabolism, tricarboxylic acid cycle, fatty acid degradation, and degradation of cholesterol and other steroids. In addition, the expression pattern of different members of several HSP gene families varied, with some being upregulated, as expected, and some remaining unchanged, consistent with the function of cognate HSPs. Interestingly, some HSP gene family members were downregulated. The expression pattern of members of surface protein gene families, such as trans-sialidases, GP63, mucins, and mucin-associated proteins, also varied, although the physiological significance of these patterns remains unclear. We conclude that T. cruzi epimastigotes are mostly prepared for a temperature increase to 37 ºC and show a standard eukaryotic response to a severe heat shock at 40 ºC.
