Leishmania infantum NTPDase1 and NTPDase2 play an important role in infection and nitric oxide production in macrophages.

Leishmania infantum, the causative agent of American Visceral Leishmaniasis (VL), is known for its ability to modulate the host immune response to its own favor. Ecto-nucleoside triphosphate diphosphohydrolase (ENTPDase) represents a family of enzymes that hydrolyze nucleotides and are involved in nucleotide-dependent biological processes. L.

Genetic depletion of the RNA helicase DDX3 leads to impaired elongation of translating ribosomes triggering co-translational quality control of newly synthesized polypeptides.

DDX3 is a multifaceted RNA helicase of the DEAD-box family that plays central roles in all aspects of RNA metabolism including translation initiation. Here, we provide evidence that the Leishmania DDX3 ortholog functions in post-initiation steps of translation. We show that genetic depletion of DDX3 slows down ribosome movement resulting in elongation-stalled ribosomes, impaired translation elongation and decreased de novo protein synthesis.

The AAA + ATPase valosin-containing protein (VCP)/p97/Cdc48 interaction network in Leishmania.

Valosin-containing protein (VCP)/p97/Cdc48 is an AAA + ATPase associated with many ubiquitin-dependent cellular pathways that are central to protein quality control. VCP binds various cofactors, which determine pathway selectivity and substrate processing. Here, we used co-immunoprecipitation and mass spectrometry studies coupled to in silico analyses to identify the Leishmania infantum VCP (LiVCP) interactome and to predict molecular interactions between LiVCP and its major cofactors.

Valosin-containing protein VCP/p97 is essential for the intracellular development of Leishmania and its survival under heat stress.

Valosin-containing protein (VCP)/p97/Cdc48 is one of the best-characterised type II cytosolic AAA+ ATPases most known for their role in ubiquitin-dependent protein quality control. Here, we provide functional insights into the role of the Leishmania VCP/p97 homologue (LiVCP) in the parasite intracellular development. We demonstrate that although LiVCP is an essential gene, Leishmania infantum promastigotes can grow with less VCP.

The Pumilio-domain protein PUF6 contributes to SIDER2 retroposon-mediated mRNA decay in .

and other trypanosomatid protozoa lack control at the level of transcription initiation and regulate gene expression exclusively post-transcriptionally. We have reported previously that harbors a unique class of hort nterspersed generate etroposons (SIDERs) that are predominantly located within 3'UTRs and play a major role in post-transcriptional control. We have shown that members of the SIDER2 subfamily initiate mRNA decay through endonucleolytic cleavage within the second conserved 79-nt signature sequence of SIDER2 retroposons.

DDX3 DEAD-box RNA helicase plays a central role in mitochondrial protein quality control in Leishmania.

DDX3 is a highly conserved member of ATP-dependent DEAD-box RNA helicases with multiple functions in RNA metabolism and cellular signaling. Here, we describe a novel function for DDX3 in regulating the mitochondrial stress response in the parasitic protozoan Leishmania. We show that genetic inactivation of DDX3 leads to the accumulation of mitochondrial reactive oxygen species (ROS) associated with a defect in hydrogen peroxide detoxification.

Adjuvanted inactivated influenza A(H3N2) vaccines induce stronger immunogenicity in mice and confer higher protection in ferrets than unadjuvanted inactivated vaccines.

Influenza viruses are major respiratory pathogens and the development of improved vaccines to prevent these infections is of high priority. Here, we evaluated split inactivated A(H3N2) vaccines (A/Uruguay/716/2007) combined or not with adjuvants (AS03, AS25 and Protollin) and administered by three different routes, intramuscular (i.m.

An Alba-domain protein contributes to the stage-regulated stability of amastin transcripts in Leishmania.

Leishmania infantum promastigotes differentiate into amastigote forms within the phagolysosome of mammalian macrophages causing visceral leishmaniasis. Delta-amastins belong to a multigenic surface protein family of potential virulence factors that are specifically expressed in the amastigote life cycle stage through distinct regulatory elements in the 3' UTR controlling either mRNA stability or translation. Here, we provide novel insights on trans-acting factors regulating amastin developmental gene expression.

Novel features of a PIWI-like protein homolog in the parasitic protozoan Leishmania.

In contrast to nearly all eukaryotes, the Old World Leishmania species L. infantum and L. major lack the bona fide RNAi machinery genes.

Promastigote to amastigote differentiation of Leishmania is markedly delayed in the absence of PERK eIF2alpha kinase-dependent eIF2alpha phosphorylation.

The parasitic protozoan Leishmania is the etiological agent of human leishmaniasis worldwide. It undergoes cellular differentiation from the sandfly promastigote form into amastigotes within mammalian macrophages, a process that is essential for its intracellular survival. Here, we characterized the Leishmania infantum PERK eIF2alpha kinase homologue and addressed its role in the parasite's cytodifferentiation.

Rapid decay of unstable Leishmania mRNAs bearing a conserved retroposon signature 3'-UTR motif is initiated by a site-specific endonucleolytic cleavage without prior deadenylation.

We have previously shown that the Leishmania genome possess two widespread families of extinct retroposons termed Short Interspersed DEgenerated Retroposons (SIDER1/2) that play a role in post-transcriptional regulation. Moreover, we have demonstrated that SIDER2 retroposons promote mRNA degradation. Here we provide new insights into the mechanism by which unstable Leishmania mRNAs harboring a SIDER2 retroposon in their 3'-untranslated region are degraded.

A novel class of developmentally regulated noncoding RNAs in Leishmania.

Leishmania is a protozoan parasite that causes serious morbidity and mortality in humans worldwide. The ability of these parasites to survive within the phagolysosomes of mammalian macrophages is dependent on the developmental regulation of a variety of genes. Identifying genomic sequences that are preferentially expressed during the parasite's intracellular growth would provide new insights about the mechanisms controlling stage-specific gene regulation for intracellular development of the parasite.

Formation of linear inverted repeat amplicons following targeting of an essential gene in Leishmania.

Attempts to inactivate an essential gene in the protozoan parasite Leishmania have often led to the generation of extra copies of the wild-type alleles of the gene. In experiments with Leishmania tarentolae set up to disrupt the gene encoding the J-binding protein 1 (JBP1), a protein binding to the unusual base beta-D-glucosyl-hydroxymethyluracil (J) of Leishmania, we obtained JBP1 mutants containing linear DNA elements (amplicons) of approximately 100 kb. These amplicons consist of a long inverted repeat with telomeric repeats at both ends and contain either the two different targeting cassettes used to inactivate JBP1, or one cassette and one JBP1 gene.

A common mechanism of stage-regulated gene expression in Leishmania mediated by a conserved 3'-untranslated region element.

Developmental regulation of mRNA levels in trypanosomatid protozoa is determined post-transcriptionally and often involves sequences located in the 3'-untranslated regions (3'-UTR) of the mRNAs. We have previously identified a developmentally regulated gene family in Leishmania encoding the amastin surface proteins and showed that stage-specific accumulation of the amastin mRNA is mediated by sequences within the 3'-UTR. Here we identified a 450-nt region within the amastin 3'-UTR that can confer amastigote-specific gene expression by a novel mechanism that increases mRNA translation without an increase in mRNA stability.

Reduced infectivity of a Leishmania donovani biopterin transporter genetic mutant and its use as an attenuated strain for vaccination.

Pterins are essential for the growth of Leishmania species, and recent work has led to the isolation of the biopterin transporter BT1. In this study, we inactivated the Leishmania donovani biopterin transporter BT1 by gene disruption mediated by homologous recombination. No transport of biopterin was detected in this mutant.