title: Downregulation of mitogen-activated protein kinase 1 of Leishmania donovani field isolates is associated with antimony resistance.
abstract: Emergence of resistance to pentavalent antimonials has become a severe obstacle in the treatment of visceral leishmaniasis (VL) on the Indian subcontinent. The mechanisms operating in laboratory-generated strains are somewhat known, but the determinants of clinical antimony resistance are not well understood. By utilizing a DNA microarray expression profiling approach, we identified a gene encoding mitogen-activated protein kinase 1 (MAPK1) for the kinetoplast protozoan Leishmania donovani (LdMAPK1) that was consistently downregulated in antimony-resistant field isolates. The expression level of the gene was validated by real-time PCR. Furthermore, decreased expression of LdMAPK1 was also confirmed at the protein level in resistant isolates. Primary structure analysis of LdMAPK1 revealed the presence of all of the characteristic features of MAPK1. When expressed in Escherichia coli, the recombinant enzyme showed kinase activity with myelin basic protein as the substrate and was inhibited by staurosporine. Interestingly, overexpression of this gene in a drug-sensitive laboratory strain and a resistant field isolate resulted in increased the sensitivity of the transfectants to potassium antimony tartrate, suggesting that it has a role in antimony resistance. Our results demonstrate that downregulation of LdMAPK1 may be in part correlated with antimony drug resistance in Indian VL isolates.
authors: Division of Biochemistry, Central Drug Research Institute, Council of Scientific and Industrial Research, Chattar Manzil Palace, Lucknow, India.
authors: Ashutosh
authors: Mansi
authors: M
authors: Garg
authors: Shyam
authors: S
authors: Sundar
authors: Robert
authors: R
authors: Duncan
authors: Hira L
authors: HL
authors: Nakhasi
authors: Neena
authors: N
authors: Goyal
mesh_terms: D000965:Antimony / Q000494:pharmacology*; D000981:Antiprotozoal Agents / Q000494:pharmacology; D015536:Down-Regulation; D004351:Drug Resistance; D004926:Escherichia coli; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D007194:India; D007700:Kinetics; D007893:Leishmania donovani / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D007898:Leishmaniasis, Visceral / Q000188:drug therapy* / Q000469:parasitology; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics* / Q000378:metabolism; D009186:Myelin Sheath / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D021261:Parasitic Sensitivity Tests; D015800:Protozoan Proteins / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000235:genetics; D019311:Staurosporine / Q000494:pharmacology
chemical_list: D000981:Antiprotozoal Agents; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D000965:Antimony; D019950:Mitogen-Activated Protein Kinase 1; D019311:Staurosporine