Trypanosoma cruzi High Mobility Group B protein (TcHMGB) can alter the nuclear structure affecting the parasite fitness

CRIBB, PAMELA; GONÇALVES, CAMILA; SERRA, ESTEBAN; MACHADO MOTTA, MARIA CRISTINA M.; ELIAS, MARIA CAROLINA; TAVERNELLI, LUIS; SANTOS DA SILVA, MARCELO

Resistencia, Chaco

Congreso; XXX Reunión Anual de la Sociedad Argentina de Protozoología; 2018

Sociedad Argentina de Protozoología

Kinetoplastid parasites, included Trypanosoma cruzi, the causal agent of Chagas disease, are uniqueregarding genome organization and gene expression. Although they regulate gene expression mainlypost-transcriptionally, chromatin accessibility plays a fundamental role in transcription initiation. Highmobility group B (HMGB) proteins are abundant non-histone chromatin proteins that play key roles inimportant nuclear functions like transcription, DNA replication, recombination and repair. TcHMGB,the HMGB from Trypanosoma cruzi has two HMG box domains like mammalian HMGBs, and a 110amino acid long N-terminal domain that is conserved among the TriTryp sequences (70?80 % similarity)and seems to be restricted to kinetoplastid HMGBs. In vitro studies showed that TcHMGB canrecognize and bind distorted DNA structures such as cruciform or small circular DNA molecules, likeits orthologs. It also has other architectural functions like the ability to bend the linear DNA, thusmodifying the DNA structure. Immunofluorescence and western blot assays showed that TcHMGB is anuclear protein expressed in all life cycle stages. However, protein levels vary throughout the life cyclein an apparent correlation with the known differences in chromatin structure and transcription ratesof the replicative versus non-replicative forms. Using an inducible expression system, we verified thatTcHMGB can also act as an architectural protein in vivo. TcHMGB over-expression induced changesin the T. cruzi nuclear structure, showing a marked reduction of the nucleolus and an increase in theeuchromatin:heterochromatin ratio. Epimastigotes replication rate was markedly reduced presumablyassociated to a delayed cell cycle progression with accumulation of parasites in G2/M phase and impairedcytokinesis. Some functions involved in pathogenesis were also altered in TcHMGB-overexpressingparasites, like the decreased efficiency of trypomastigotes to infect cells in vitro, the reduction of intracellularamastigotes replication and the number of released trypomastigotes. Finally, we also observedthat TcHMGB can be secreted, and induce the production of inflammatory mediators in mammaliancells, suggesting a putative role for the protein in the interaction with the host cell. Taken together,our results show that the TcHMGB protein is a pleiotropic player that controls cell phenotype and it is involved in key cellular processes.