Cyclic AMP compartmentalization drives signal specificity to control vector colonization and mammalian host infection by American trypanosomes

Abstract

Cyclic AMP (cAMP) signaling is crucial for environmental sensing and response to stress conditions in trypanosomatids. However, the mechanisms driving the specificity of cAMP signals remain poorly understood in these protozoan parasites. We recently identified two putative cAMP microdomains in Trypanosoma cruzi, the causative agent of Chagas disease. Here, considering the localization of three phosphodiesterases, PDEC at the contractile vacuole complex (CVC), and PDEB1 and PDEB2 along the flagellum, we modulated their expression to functionally characterize the flagellar tip (FT) and the CVC as individual cAMP microdomains, named FT-cAMP and CVC-cAMP, respectively. We generated PDE knockout and overexpression cell lines to selectively alter cAMP signals generated in each compartment. Our results indicate that FT-cAMP mediates cell adhesion, metacyclogenesis, host cell invasion, and intracellular replication, while CVC-cAMP is required for osmoregulation and epimastigote proliferation. In addition, ablation of flagellar PDEB1 and PDEB2 enhanced the parasites ability to colonize the hindgut of the triatomine vector, whereas PDEC-KO parasites were impaired in their establishment in the insects hindgut. The observed phenotypes were compartment-specific, demonstrating functional segregation between the two cAMP microdomains. Our data provide robust evidence on the presence of compartmentalized cAMP signals in T. cruzi, linking the role of locally synthesized cAMP pools to specific cellular responses during the parasites life cycle. Author summaryChagas disease is a life-threatening infectious disease caused by the protozoan parasite Trypanosoma cruzi, which is spread through the feces of infected kissing bugs. The parasite survives in challenging environments as it transitions between the insect vector and the mammalian host by differentiating into distinct developmental forms. cAMP is a universal second messenger that mediates specific cellular processes in the life cycle of T. cruzi. However, the spatial-temporal dynamics of cAMP signal remain largely unexplored in trypanosomes. We previously reported several cAMP signaling proteins in two compartments of T. cruzi: the contractile vacuole complex (CVC) and the flagellar tip (FT). In this study, we characterized the individual functions of these microdomains. We specifically disturbed cAMP signaling in these compartments by modulating the expression of their resident phosphodiesterases. We observed that the FT microdomain is specifically involved in parasite differentiation, host cell invasion, intracellular replication, and vector colonization, while the CVC microdomain is important for osmoregulation and parasite survival within the kissing bug. Our results unequivocally demonstrate that T. cruzi utilizes specific cAMP pools to address different environmental challenges. These findings highlight cAMP signaling as an essential pathway that could be further explored for the development of novel antiparasitic interventions.