Trypanosoma cruzi is the causative agent of Chagas disease, endemic to Latin America and a public health problem in Brazil. This disease still depends on treatment by the same drugs as in the 1970s, and the search for new drugs is a challenge due to the resistance of T. cruzi to treatments. During its complex life cycle, T. cruzi transitions between the insect vector and the mammalian host, facing different conditions which its four life forms are adapted to. Among these life forms, amastigotes (in the mammalian host) and epimastigote (in the insect vector) are able to replicate, expand the population of T. cruzi and differentiate themselves into infectious forms that are unable to replicate. The interruption of proliferation in the transition to infectious forms is a remarkable event and it is known to be triggered by nutritional stress and environmental factors, but how it is regulated remains unknown. CDKs and cyclins regulate cell proliferation and quiescence in model eukaryotes. In T. cruzi the CDKs counterparts, the CRKs (Cdc2-related kinase), and the cyclins act in the control of the cell cycle and the control of replication is an important factor involved in the persistence of this parasite. Cyclin 5 stands out among the cyclins for being able to interact with the two characterized CRKs (CRK1 and CRK3) and for presenting phosphorylation sites that are modulated during metacyclogenesis in trypomastigotes after contact with the extracellular matrix. Thus, this proposal aims to characterize the role of cyclin 5 throughout the cell cycle of T. cruzi and also its entry into quiescence, during metacyclogenesis. Using CRISPR / Cas9 reverse genetics, it will be possible to express cyclin 5 conjugated to the tag epitope, in addition to generating Knockout (or hemi-konckout) strains in order to evaluate the role of this cyclin in T. cruzi.
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