Transcriptomic response to different heme sources in <i>Trypanosoma cruzi</i> epimastigotes

Heme is an essential molecule for most organisms, yet some parasites, like <i>Trypanosoma cruzi</i>, the causative agent of Chagas disease, cannot synthesize it. These parasites must acquire heme from their hosts, making this process critical for their survival. In the midgut of the insect vector, <i>T. cruzi</i> epimastigotes are exposed to both hemoglobin (Hb) and free heme resulting from its degradation. Despite the importance of this nutrient, how different heme sources influence parasite gene expression remains poorly understood. Here, we showed that heme restitution either as hemin or Hb to heme-starved parasites induces an early and distinct transcriptional response in <i>T. cruzi</i> epimastigotes. Using RNA sequencing at 4- and 24-hours post-supplementation, we identified gene subsets commonly or uniquely regulated by each heme source, including genes putatively linked to heme acquisition and metabolism. The study includes the first focused characterization of CRAL/TRIO domain-containing protein (TcCRAL/TRIO), a novel heme-responsive hemoprotein. Our results provide a more detailed picture of <i>T. cruzi</i> biology and highlights heme acquisition as a promising point of vulnerability to control parasite proliferation.