TRYPANOSOMA CRUZI PHENOTYPIC DIVERSITY: A ROLE FOR MUCIN-LIKE MOLECULES

A BUSCAGLIA, CARLOS; CAMARA MM; CANEPA GE; CARMONA SJ; PANUNZI LG; AGÜERO F; GARCIA ES; AZAMBUJA P; GONZALEZ MS; FLEMMING I; ALFONZO JD

Caxambu

Congreso; XXXII Reunião Anual da Sociedade Brasileira de Protozoologia; 2016

Sociedade Brasileira de Protozoologia (SBPz)

[Abstract ID: 2029] PALESTRA/TALKPALESTRANTE/INVITED SPEAKERTRYPANOSOMA CRUZI PHENOTYPIC DIVERSITY: A ROLE FOR MUCIN-LIKE MOLECULES BUSCAGLIA, C.A.1; CAMARA, M.L.M.2; CANEPA, G.E.3; CARMONA, S.J.4; PANUNZI, L.5; AGÜERO, F.6; GARCIA, E.S.7; AZAMBUJA, P.8; GONZALEZ, M.S.9; FLEMMING, I.10; ALFONZO, J.D.11. 1,2,3,4,5,6.IIB-INTECH (UNSAM-CONICET), BUENOS AIRES - ARGENTINA ; 7,8.INSTITUTO OSWALDO CRUZ, RIO DE JANEIRO - RJ - BRAZIL; 9.UNIVERSIDAD FEDERAL FLUMINENSE, RIO DE JANEIRO - RJ - BRAZIL; 10,11.THE OHIO STATE UNIVERSITY, COLUMBUS - ESTADOS UNIDOS . Funding Agency : ANPCyT (Argentina) and Fundacion Bunge y Born (Argentina). Keywords: Trypanosoma cruzi;mucin;codon adaptation Resume Due to its predominant clonal proliferation, Trypanosoma cruzi exhibits a highly-structured population, composed of multiple strains displaying considerable genetic drift. This genetic variability, in turn has a major impact at the phenotypic level, when parameters such as antigenic profile, virulence, growth rate, pathogenicity, tissue tropism, and sensitivity to anti-chagasic drugs are considered. Therefore, one of the main objectives of Chagas Disease research remains to elucidate the molecular and cellular basis underlying T. cruzi phenotypic variation. The surface coat of T. cruzi is covered in different glycoconjugates which contribute to parasite protection and to the establishment of a persistent infection. Mucins are major components of this coat. These are glycoproteins attached to the parasite membrane through a glycosylphosphatidylinositol anchor in which the oligosaccharide chains are O-glycosidically linked to threonine or serine residues via NAcGlc units. TcSMUG L comprises a group of genes coding for small T. cruzi mucins anchored to and secreted from the surface of replicative, insect-dwelling developmental forms (i.e. epimastigotes). Here, we show that the N-terminal peptide of TcSMUG L mucins promotes adhesion of epimastigotes to the posterior midgut epithelial cells of the triatomine vector Rhodnius prolixus, a key step for metacyclogenesis (i.e. conversion of epimastigotes to infective, metacyclic trypomastigotes). In addition, we show results obtained from transgenic lines over-expressing TcSMUG L products that further support this idea, and that indicate that these molecules play also a key role during metacyclogenesis in vitro. Interestingly, and in spite of showing a high degree of conservation across paralogues and orthologues from different isolates, TcSMUG L expression at both mRNA and protein levels is quite variable among T. cruzi strains. Here, we also show that differences in TcSMUG L expression correlate with bias in threonine codon utilization between strains, which correlates with changes in the levels of adenosine-to-inosine editing of tRNAs, and particularly of threonine decoding tRNAs, suggesting tRNA editing as a forcible step in controlling expression of TcSMUG L (and likely other T. cruzi genes) while driving codon adaptation. Moreover, in vivo manipulation of tRNA editing deaminase (ADAT) complex expression leads to increases in the levels of tRNA adenosine-to-inosine editing, and significantly impacts the expression of TcSMUG L proteins but not TcSMUG L transcripts. These variations are also observed upon ectopic expression of synthetic TcSMUG L constructs displaying contrasting threonine codon bias in isogenic parasite background. Overall, our data indicate that TcSMUG L mucins are key determinants of the infectivity of T. cruzi towards the insect population and that, due to inter-strain differences on their expression, these molecules might also contribute to the parasite phenotypic variability. Regarding the latter phenomenon, our data support the existence of a novel control mechanism likely operating at the level of TcSMUG L mRNA translation elongation. These observations open a novel perspective on regulation of gene expression in T. cruzi (and trypanosomatids in general) which still relies extensively on post-transcriptional events, yet our findings depart from the more widely accepted mechanism of regulation at the level of mRNA abundance.