The recombinase Rad51 plays a key role in events of genetic exchange in Trypanosoma cruzi

Abstract

Detection of genetic exchange has been a limiting factor to deepen the knowledge on the mechanisms by which Trypanosoma cruzi is able to generate progeny and genetic diversity. Here we show that incorporation of halogenated thymidine analogues, followed by immunostaining, is a reliable method not only to detect T. cruzi fused-cell hybrids, but also to quantify their percentage in populations of this parasite. Through this approach, we were able to detect and quantify fused-cell hybrids of T. cruzi clones CL Brener and Y. Given the increased detection of fused-cell hybrids in naturally-occurring hybrid CL Brener strain, which displays increased levels of RAD51 and BRCA2 transcripts, we further investigated the role of Rad51 – a recombinase involved in homologous recombination – in the process of genetic exchange. We also verified that the detection of fused-cell hybrids in T. cruzi overexpressing RAD51 is increased when compared to wild-type cells, suggesting a key role for Rad51 either in the formation or in the stabilization of fused-cell hybrids in this organism.

The Influence of Recombinational Processes to Induce Dormancy in Trypanosoma cruzi

“…We have described previously that distinct responses to DSBs, through homologous recombination, observed in different T. cruzi DTUs are related to their variable TcRAD51 transcription levels (Alves et al, 2018). Then, in order to verify if there is a direct relation between TcRAD51 mRNA levels and the rate of arrested cells in the strains studied here-Dm28c, Y, CL Brener, and Bug-we performed a qRT-PCR assay to determine the TcRAD51 transcription levels.…”

“…Homologous recombination and TcRad51 also play a relevant role in genetic exchange processes since the overexpression of TcRAD51 is capable of stabilizing hybrid T. cruzi cells. In fact, naturally-hybrid T. cruzi's populations show higher expression of TcRAD51 when compared to the non-hybrid ones (Alves et al, 2018).…”

“…Our group has shown through different works that homologous recombination is essential in T. cruzi once it allows this parasite to repair DNA double strand breaks (DSBs), as well as it is also implicated in genetic exchange between T. cruzi cells (Alves et al, 2018). We have also shown that this parasite survives up to 500 Gy of gamma radiationwhich induces DSBs-repairing DNA lesions within 48 h, and recovering cell growth 96 h after irradiation (Regis-da-Silva et al, 2006).…”

Evidence of hybridization, mitochondrial introgression and biparental inheritance of the kDNA minicircles in Trypanosoma cruzi I

“…In spite of being recently proposed by genomic studies [14,20] meiosis has not been reported for T. cruzi in the laboratory yet. Alternatively, experimental tetraploid or sub-tetraploid hybrids were observed in laboratory conditions [21,22]. The fusion of diploid cells to form a tetraploid and posterior random loss of chromosomes slowly returning to diploidy was proposed as a model to explain genetic exchange in this species [21].…”

Conditional knockout of RAD51-related genes inLeishmania majorreveals a critical role for homologous recombination during genome replication

“…In Trypanosoma brucei, HR factors have been clearly implicated in the directed recombination of Variant Surface Glycoprotein (VSG) genes during host immune evasion by antigenic variation (21), as well as in maintenance of the massive subtelomeric VSG gene archive (22,23). In T. cruzi, HR has been suggested to be a driver of variability in multigene families (24,25) and in cell hybridisation (26). Finally, in Leishmania, HR related factors have been implicated in mediating the formation or maintenance of episomes, which appear to form stochastically, arise genome-wide and have been implicated in acquisition of drug resistance (27)(28)(29)(30)(31)(32).…”