Leishmania-induced inactivation of the macrophage transcription factor AP-1 is mediated by the parasite metalloprotease GP63.
Leishmania parasites have evolved sophisticated mechanisms to subvert macrophage immune responses by altering the host cell signal transduction machinery, including inhibition of JAK/STAT signalling and other transcription factors such as AP-1, CREB and NF-κB. AP-1 regulates pro-inflammatory cytokines, chemokines and nitric oxide production. Herein we show that upon Leishmania infection, AP-1 activity within host cells is abolished and correlates with lower expression of 5 of the 7 AP-1 subunits. Of interest, c-Jun, the central component of AP-1, is cleaved by Leishmania. Furthermore, the cleavage of c-Jun is dependent on the expression and activity of the major Leishmania surface protease GP63. Immunoprecipitation of c-Jun from nuclear extracts showed that GP63 interacts, and cleaves c-Jun at the perinuclear area shortly after infection. Phagocytosis inhibition by cytochalasin D did not block c-Jun down-regulation, suggesting that internalization of the parasite might not be necessary to deliver GP63 molecules inside the host cell. This observation was corroborated by the maintenance of c-Jun cleavage upon incubation with L. mexicana culture supernatant, suggesting that secreted, soluble GP63 could use a phagocytosis-independent mechanism to enter the host cell. In support of this, disruption of macrophage lipid raft microdomains by Methyl β-Cyclodextrin (MβCD) partially inhibits the degradation of full length c-Jun. Together our results indicate a novel role of the surface protease GP63 in the Leishmania-mediated subversion of host AP-1 activity.
Contreras
Irazú
I
Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada.
Gómez
María Adelaida
MA
Nguyen
Oliver
O
Shio
Marina T
MT
McMaster
Robert W
RW
Olivier
Martin
M
D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D015536:Down-Regulation; D005786:Gene Expression Regulation; D057131:Immune Evasion / Q000235:genetics / Q000502:physiology; D007891:Leishmania / Q000235:genetics / Q000502:physiology*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D045726:Metalloproteases / Q000378:metabolism / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D030781:Organisms, Genetically Modified; D011485:Protein Binding / Q000502:physiology; D011499:Protein Processing, Post-Translational / Q000502:physiology; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors / Q000378:metabolism*
D018808:Transcription Factor AP-1; D045726:Metalloproteases; D008666:Metalloendopeptidases; C055146:glycoprotein gp63, Leishmania