Protein methyltransferase 7 deficiency in Leishmania major increases neutrophil associated pathology in murine model

Abstract

Leishmania major is the main causative agent of cutaneous leishmaniasis in the Old World. In Leishmania parasites, the lack of transcriptional control is mostly compensated by post-transcriptional mechanisms. Methylation of arginine is a conserved post-translational modification executed by Protein Arginine Methyltransferase (PRMTs). The genome from L. major encodes five PRMT homologs, including the cytosolic protein associated with several RNA-binding proteins, LmjPRMT7. It has been previously reported that LmjPRMT7 could impact parasite infectivity. In addition, a more recent work has clearly shown the importance of LmjPRMT7 in RNA-binding capacity and protein stability of methylation targets, demonstrating the role of this enzyme as an important epigenetic regulator of mRNA metabolism. In this study, we unveil the impact of PRMT7-mediated methylation on parasite development and virulence. Our data reveals that higher levels of LmjPRMT7 can impair parasite pathogenicity, and that deletion of this enzyme rescues the pathogenic phenotype of an attenuated strain of L. major. Interestingly, lesion formation caused by LmjPRMT7 knockout parasites is associated with an exacerbated inflammatory reaction in the tissue correlated with an excessive neutrophil recruitment. Moreover, the absence of LmjPRMT7 also impairs parasite development within the sand fly vector Phlebotomus duboscqi. Finally, a transcriptome analysis shed light onto possible genes affected by depletion of this enzyme. Taken together, this study highlights how post-transcriptional regulation can affect different aspects of the parasite biology.

High-speed, three-dimensional imaging reveals chemotactic behaviour specific to human-infective Leishmania parasites

“…Both hMφ (the definitive host cells) and neutrophils are drawn to sites of infection during inflammation, while resident dermal macrophages may act as host cells facilitating persistence ( Lee et al, 2020 ). Chemical gradients are known to occur and persist in cutaneous infections, as damage to tissue, sandfly saliva and Leishmania -derived molecules have been shown to recruit immune cells by this mechanism ( Dey et al, 2018 ; Giraud et al, 2018 ; Alcoforado Diniz et al, 2021 ). META cells have also been observed to move within the skin, away from their site of introduction ( Peters et al, 2008 ).…”

Functional study ofLeishmania braziliensisprotein arginine methyltransferases (PRMTs) reveals that PRMT1 and PRMT5 are required for macrophage infection

“…Due to the difficulties associated with genetically manipulating Leishmania spp. via classical homologous recombination techniques, we repurposed the CRISPR/Cas9 system previously developed by Beneke et al (28) and generated an L. braziliensis strain expressing both Cas9 and T7 RNA polymerase, named pT007. The expression of Cas9 was confirmed by western blotting with antibodies against the Flag tag (Fig.…”

“…To date, of the five classic PRMT homologs present in the Leishmania genome, only studies on Leishmania major PRMT7 have been reported (12). We have previously shown that the Lmj PRMT7 levels are inversely correlated with the pathogenicity of L. major in vitro and in vivo (27, 28). In addition, Ferreira and coworkers showed that Leishmania PRMT7 acts as an epigenetic regulator of mRNA metabolism and provided mechanistic insight into the functional regulation of RBPs by methylation (29).…”

Arginine Methyltransferases as Regulators of RNA-Binding Protein Activities in Pathogenic Kinetoplastids

“…Concordantly, the virulent L. major LV39 strain expressed lower levels of LmjPRMT7 than the avirulent CC1 strain (Ferreira et al, 2014) and knockout of LmjPRMT7 in the CC1 strain recovered its virulence (Diniz et al, 2021). Curiously, gain of virulence upon LmjPRMT7 deletion was not linked to an increase in parasite burden, but to increased recruitment of neutrophils to the site of infection (Diniz et al, 2021). Further studies will investigate the biological process underlying this altered immune response.…”

“…Despite only minor changes in the global transcriptome of LmjPRMT7-KO parasites, this mutation had a clear biological impact as LmjPRMT7-KO cells are more virulent in vitro and in vivo than wildtype L. major (Ferreira et al, 2014;Diniz et al, 2021). Concordantly, the virulent L. major LV39 strain expressed lower levels of LmjPRMT7 than the avirulent CC1 strain (Ferreira et al, 2014) and knockout of LmjPRMT7 in the CC1 strain recovered its virulence (Diniz et al, 2021). Curiously, gain of virulence upon LmjPRMT7 deletion was not linked to an increase in parasite burden, but to increased recruitment of neutrophils to the site of infection (Diniz et al, 2021).…”