Regulation of macrophage gene expression by Mycobacterium tuberculosis: down-regulation of mitochondrial cytochrome c oxidase.
We have investigated changes in gene expression in mouse peritoneal macrophages following infection with virulent Mycobacterium tuberculosis. Using differential-display reverse transcription-PCR (RT-PCR), we have identified a gene that was markedly down-regulated within 6 h of infection and remained so for the duration of the experiment (5 days). On sequencing, this gene was found to encode the murine cytochrome c oxidase subunit VIIc (COX VIIc). Down-regulation of COX VIIc during M. tuberculosis infection was confirmed by three independent techniques: limiting-dilution RT-PCR, RNase protection assay, and Northern analysis. Limiting-dilution RT-PCR and Northern analysis were also used to analyze the specificity of this regulation; heat-killed M. tuberculosis, Mycobacterium bovis BCG, and latex beads had no effect on expression of COX VIIc. Down-regulation of this enzyme was also confirmed by using adherent cells isolated from spleens of M. tuberculosis-infected mice. These ex vivo macrophages showed apoptotic features, suggesting a possible involvement of cytochrome c oxidase in the programmed cell death of the host cells.
Ragno
S
S
Division of Mycobacterial Research, National Institute for Medical Research, London NW7 1AA, United Kingdom.
Estrada-Garcia
I
I
Butler
R
R
Colston
M J
MJ
D000818:Animals; D017209:Apoptosis; D001483:Base Sequence; D002478:Cells, Cultured; D004195:Disease Models, Animal; D015536:Down-Regulation; D003576:Electron Transport Complex IV / Q000235:genetics*; D005260:Female; D008264:Macrophages / Q000201:enzymology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger; D013154:Spleen / Q000166:cytology; D014376:Tuberculosis / Q000201:enzymology
D003576:Electron Transport Complex IV; D009687:Nuclear Proteins; D012333:RNA, Messenger; C105520:COX7C protein, human