This hypothesis has been recently verified by ACP-196 mouse experiments in which we over-expressed one δ-amastin gene in the G strain and showed that the transfected parasites have accelerated amastigote differentiation into trypomastigotes in in vitro infections as well as parasite dissemination in tissues after infection in mice [19]. It is also noteworthy that both β-amastins exhibited increased levels in epimastigotes of all strains analysed, indicating that this amastin isoform may be involved

with see more parasite adaptation to the insect vector. These results are consistent with previous reports describing microarray and qRT-PCR analyses of the steady-state T. cruzi transcriptome, in which higher levels of β-amastins were detected in epimastigotes compared to amastigotes and trypomastigote forms [20]. Similar findings were also described for one Leishmania infantum amastin gene (LinJ34.0730), whose transcript was detected in higher levels in promastigotes after five days in contrast to all other amastin genes that showed higher expression levels in amastigotes [8]. The generation of knock-out parasites with the β-amastin locus deleted and

pull-down assays 4EGI-1 order to investigate protein interactions between the distinct T. cruzi amastins and host cell proteins will help elucidate the function of these proteins. Figure 3 Amastin mRNA expression during the T. cruzi life cycle in different parasite strains.

Total Glycogen branching enzyme RNA was extracted from epimatigote (E), trypomastigote (T) and amastigote forms (A) from CL Brener, Y, G and Sylvio X-10. Electrophoresed RNAs (~10 μg/lane) were transferred to nylon membranes and probed with the 32P- labelled sequences corresponding to δ-amastin, δ-Ama40, β1- and β2-amastins (top panels). Bottom panels show hybridization of the same membranes with a fragment of the 24Sα rRNA. Also, to investigate the mechanisms controlling the expression of the different sub-classes of amastins, sequence alignment of the 3’UTR sequences from β- and δ-amastins were done. Previous work has identified regulatory elements in the 3’ UTR of δ-amastins as well as in other T. cruzi genes controlling mRNA stability [4–6, 21, 22] and mRNA translation [23]. Since we observed that the two groups of amastin genes have highly divergent sequences in their 3’UTR (not shown), we are preparing luciferase reporter constructs to identify regulatory elements that might be present in the β-amastin transcripts as well as to identify the factors responsible for the differences observed in the amastin gene expression in distinct T. cruzi strains. Amastin cellular localization In our initial studies describing a member of the δ-amastin sub-family, we showed that this glycoprotein localizes in the plasma membrane of intracellular amastigotes [3].