title: Mechanism of down-regulation of RNA polymerase III-transcribed non-coding RNA genes in macrophages by Leishmania.
abstract: The parasitic protozoan Leishmania invades mammalian macrophages to establish infection. We reported previously that Leishmania manipulates the expression of several non-coding RNA genes (e.g. Alu RNA, B1 RNA, and signal recognition particle RNA) in macrophages to favor the establishment of their infection in the phagolysosomes of these cells (Ueda, Y., and Chaudhuri, G. (2000) J. Biol. Chem. 275, 19428-19432; Misra, S., Tripathi, M. K., and Chaudhuri, G. (2005) J. Biol. Chem. 280, 29364-29373). We report here the mechanism of this down-regulation. We found that the non-coding RNA (ncRNA) genes that are repressed by Leishmania infection in macrophages contain a "B-box" in their promoters and thus require the polymerase III transcription factor TFIIIC for their expression. We also found that Leishmania promastigotes through their surface protease (leishmanolysin or gp63) activate the thrombin receptor PAR1 in the macrophages. This activation of PAR1 raised the cytosolic concentration of Ca(2+) into the micromolar range, thereby activating the Ca(2+)-dependent protease μ-calpain. μ-Calpain then degraded TFIIIC110 to inhibit the expression of the selected ncRNA genes. Avirulent stocks of Leishmania not expressing surface gp63 failed to down-regulate ncRNAs in the exposed macrophages. Inhibition of PAR1 or calpain 1 in macrophages made them resistant to Leishmania infection. These data suggest that macrophage PAR1 and calpain 1 are potential drug targets against leishmaniasis.
authors.affiliation: Department of Microbiology and Immunology, Meharry Medical College, Nashville, Tennessee 37208, USA.
authors.forename: Tanu
authors.initials: T
authors.lastname: Rana
authors.forename: Smita
authors.initials: S
authors.lastname: Misra
authors.forename: Mukul K
authors.initials: MK
authors.lastname: Mittal
authors.forename: Anitra L
authors.initials: AL
authors.lastname: Farrow
authors.forename: Keith T
authors.initials: KT
authors.lastname: Wilson
authors.forename: MacRae F
authors.initials: MF
authors.lastname: Linton
authors.forename: Sergio
authors.initials: S
authors.lastname: Fazio
authors.forename: Ian M
authors.initials: IM
authors.lastname: Willis
authors.forename: Gautam
authors.initials: G
authors.lastname: Chaudhuri
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002154:Calpain / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D015536:Down-Regulation; D006801:Humans; D018320:Leishmania major / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D016773:Leishmaniasis, Cutaneous / Q000235:genetics / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism* / Q000469:parasitology; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D012320:RNA Polymerase III / Q000235:genetics / Q000378:metabolism*; D022661:RNA, Untranslated / Q000096:biosynthesis* / Q000235:genetics; D044463:Receptor, PAR-1 / Q000235:genetics / Q000378:metabolism; D019474:Transcription Factors, TFIII / Q000235:genetics / Q000378:metabolism; D000098832:Transcription Factor TFIIIC
chemical_list: D022661:RNA, Untranslated; D044463:Receptor, PAR-1; D019474:Transcription Factors, TFIII; D000098832:Transcription Factor TFIIIC; D012320:RNA Polymerase III; D002154:Calpain; C112682:Capn1 protein, mouse; D008666:Metalloendopeptidases; C055146:glycoprotein gp63, Leishmania; D002118:Calcium