Overexpression of Trypanosoma cruzi High Mobility Group B protein (TcHMGB) alters the nuclear structure, impairs cytokinesis and reduces the parasite infectivity

Luis Emilio Tavernelli,Camila Silva Gonçalves,Victoria Lucia Alonso,Marcelo Santos Da Silva,Maria Cristina M Motta,Maria Carolina Elias,Esteban Serra,Pamela Cribb

doi:10.1038/s41598-018-36718-0

Abstract

Kinetoplastid parasites, included Trypanosoma cruzi, the causal agent of Chagas disease, present a unique genome organization and gene expression. Although they control gene expression mainly post-transcriptionally, chromatin accessibility plays a fundamental role in transcription initiation control. We have previously shown that High Mobility Group B protein from Trypanosoma cruzi (TcHMGB) can bind DNA in vitro. Here, we show that TcHMGB also acts as an architectural protein in vivo, since the overexpression of this protein induces changes in the nuclear structure, mainly the reduction of the nucleolus and a decrease in the heterochromatin:euchromatin ratio. Epimastigote replication rate was markedly reduced presumably due to a delayed cell cycle progression with accumulation of parasites in G2/M phase and impaired cytokinesis. Some functions involved in pathogenesis were also altered in TcHMGB-overexpressing parasites, like the decreased efficiency of trypomastigotes to infect cells in vitro, the reduction of intracellular amastigotes replication and the number of released trypomastigotes. Taken together, our results suggest that the TcHMGB protein is a pleiotropic player that controls cell phenotype and it is involved in key cellular processes.

Highlights

Trypanosoma cruzi is a hemoflagellate protozoan parasite and it is the causative agent of Chagas disease, a neglected disease endemic in Latin America
These results suggest that, as well as other High Mobility Group B (HMGB) family members, the T. cruzi HMGB can be considered as a pleiotropic factor involved in key cellular processes that may play a role in Chagas disease pathogenesis
We analyzed the plasmid-derived protein expression by western blot with antibodies directed to the hemagglutinin tag (HA)-tag and confirmed that TcHMGB protein is overexpressed in all life cycle stages and there is almost no leaky expression in the absence of tetracycline (Fig. S1C)

Summary

Introduction

Trypanosoma cruzi is a hemoflagellate protozoan parasite and it is the causative agent of Chagas disease, a neglected disease endemic in Latin America. According to Pfam (http://pfam.sanger.ac.uk/) and SUPERFAMILY (http://supfam.cs.bris.ac.uk/SUPERFAMILY/), the trypanosomatid HMGBs contain a “DEK-C terminal domain”, defined as a DNA binding structural domain found in the C-terminal region of the chromatin-associated oncoprotein DEK15 This N-terminal region bears a predicted Nuclear Localization Signal (NLS), which differs, in sequence and in location, from human HMGB1’s NLSs16. We observed a decrease in the infection rate in Vero cells, amastigotes proliferation and the number of trypomastigotes released from infected cells in vitro in TcHMGB-overexpressing parasites These results suggest that, as well as other HMGB family members, the T. cruzi HMGB can be considered as a pleiotropic factor involved in key cellular processes that may play a role in Chagas disease pathogenesis

Methods

Results

Conclusion