Reorganization of ribosomal RNA biosynthetic machinery during growth arrest and metacyclogenesis in Trypanosoma cruzi.

The nucleolus is the nuclear compartment where ribosomal RNA is transcribed and processed. In Trypanosoma cruzi, the etiological agent of Chagas disease, nucleolar activity is downregulated during growth arrest and metacyclogenesis. To investigate nucleolar organization in these conditions, we analyzed TcNop56, a component of the small nucleolar ribonucleoprotein (snoRNP) complex involved in pre-rRNA processing, using enhanced green fluorescent protein (EGFP)-tagged constructs in transfected epimastigotes. TcNop56-EGFP distribution was compared with published observations of TcRPA31-EGFP, a subunit of RNA polymerase I. Whereas TcRPA31 relocalizes from the nucleolus to the nucleoplasm during growth arrest, as previously reported, TcNop56 consistently retained a focused nucleolar localization under transcriptionally inactive conditions. This dissociation between transcription and processing markers reveals a functional reorganization of the nucleolus, highlighting the nucleolar plasticity of T. cruzi and its potential as a model for exploring nucleolar dynamics and therapeutic strategies in parasitic diseases.