Global gene expression analysis of Trypanosoma cruzi under hyperosmotic stress

ALVAREZ, V; LI, ZH; DE GAUDENZI, JG; FRASCH, AC; CAZZULO, JJ; DOCAMPO, R

Woods Hole, USA

Congreso; Kinetoplastid Molecular Cell Biology Meeting III; 2009

KMCBM

Osmoregulation is essential for Trypanosoma cruzi since it is subjectedto a variety of osmotic stresses during its life cycle. Whenepimastigotes were subjected to hyperosmotic stress (from 300 to 650mOsm, by addition of sorbitol) they shrank dramatically within a fewminutes, and did not regain their normal volume at least during thefollowing 2 h. However they adapted well to these conditions, beingvirtually indistinguishable in terms of motility from control cellsmaintained in isosmotic buffer. Treatment of the cells with low concentrationsof HgCl2, a known inhibitor of T. cruzi aquaporin 1 (TcAQP1),reduced the intensity of shrinking while there was a direct correlationbetween levels of shrinking and TcAQP1 overexpression, suggestingthat aquaporin could be mediating water efflux during osmotic challenge.Hyperosmotic stress also resulted in a great increase in the sizeof the contractile vacuole. A genome-wide transcriptional analysis ofT. cruzi epimastigotes submitted to hyperosmotic stress resulted in upregulationand down-regulation of the expression of a number of genes.Several of these changes were confirmed by northern and western blotanalyses. Sequence analysis of gene transcripts allowed the identificationof different RNA motifs, with stem-loop structures of 35-50nt, preferentially localized in the 3’-UTRs. These motifs are enrichedin the experimental dataset compared with the entire transcriptome:Up-m was found in 85% of up-regulated mRNAs (24 of 28) against21% of the T. cruzi Reference Sequence (RefSeq) database; Down-mwas present in 50% (15 of 30) of the down-regulated genes, and in 3%of the transcripts in the database. The lists of the Up-m- and Downm-containing transcripts include trans-sialidases and mucins, amongother proteins.