A processed short transcript of Leishmania, ODD1

Potential therapeutic targets shared between leishmaniasis and cancer

The association of leishmaniasis and malignancies in human and animal models has been highlighted in recent years. The misdiagnosis of coexistence of leishmaniasis and cancer and the use of common drugs in the treatment of such diseases prompt us to further survey the molecular biology of Leishmania parasites and cancer cells. The information regarding common expressed proteins, as possible therapeutic targets, in Leishmania parasites and cancer cells is scarce. Therefore, the current study reviews proteins, and investigates the regulation and functions of several key proteins in Leishmania parasites and cancer cells. The up- and down-regulations of such proteins were mostly related to survival, development, pathogenicity, metabolic pathways and vital signalling in Leishmania parasites and cancer cells. The presence of common expressed proteins in Leishmania parasites and cancer cells reveals valuable information regarding the possible shared mechanisms of pathogenicity and opportunities for therapeutic targeting in leishmaniasis and cancers in the future.

Leishmanial selenoproteins and the host immune system: towards new therapeutic strategies?

Optimum levels of selenoproteins are essential for starting and managing the host immune responses against pathogens. According to the expression of selenoproteins in Leishmania parasites, and since high levels of selenoproteins lead to adverse effects on immune cells and their functions, Leishmania parasites might then express selenoproteins such as selenomethionine in their structure and/or secretions able to challenge the host immune system. Finally, this adaptation may lead to evasion of the parasite from the host immune system. The expression of selenoproteins in Leishmania parasites might then induce the development of infection. We therefore suggest these molecules as new therapeutic candidates for the treatment of leishmaniasis.

Evidence of putative non-coding RNAs from Leishmania untranslated regions

Non-coding RNAs (ncRNAs) are regulatory elements present in a wide range of organisms, including trypanosomatids. ncRNAs transcribed from the untranslated regions (UTRs) of coding genes have been described in the transcriptomes of several eukaryotes, including Trypanosoma brucei. To uncover novel putative ncRNAs in two Leishmania species, we examined a L. major cDNA library and a L. donovani non-polysomal RNA library. Using a combination of computational analysis and experimental approaches, we classified 26 putative ncRNA in L. major, of these, 5 arising from intergenic regions and 21 from untranslated regions. In L. donovani, we classified 37 putative ncRNAs, of these, 7 arising from intergenic regions, and 30 from UTRs. Our results suggest, for the first time, that UTR-transcripts may be a common feature in the eukaryote Leishmania similarly to those previously shown in T. brucei and other eukaryotes.

Identification of Leishmania selenoproteins and SECIS element

Selenoproteins result from the incorporation of selenocysteine (Sec-U) at an UGA-stop codon positioned within a gene's open reading frame and directed by selenocysteine insertion sequence (SECIS) elements. Although the selenocysteine incorporation pathway has been identified in a wide range of organisms it has not yet been reported in the Kinetoplastida Leishmania and Trypanosoma. Here we present evidence consistent with the presence of a selenocysteine biosynthetic pathway in Kinetoplastida. These include the existence of SECIS-containing coding sequences in Leishmania major and Leishmania infantum, the incorporation of (75)Se into Leishmania proteins, the occurrence of selenocysteine-tRNA (tRNA (sec) (uca)) in both Leishmania and Trypanosoma and in addition the finding of all genes necessary for selenocysteine synthesis such as SELB, SELD, PSTK and SECp43. As in other eukaryotes, the Kinetoplastids have no identifiable SELA homologue. To our knowledge this is the first report on the identification of selenocysteine insertion machinery in Kinetoplastida, more specifically in Leishmania, at the sequence level.