Premium
Muramyl‐dipeptide‐induced mitochondrial proton leak in macrophages is associated with upregulation of uncoupling protein 2 and the production of reactive oxygen and reactive nitrogen species
Author(s) -
ElKhoury Takla G.,
Bahr Georges M.,
Echtay Karim S.
Publication year - 2011
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2011.08226.x
Subject(s) - muramyl dipeptide , downregulation and upregulation , reactive oxygen species , mitochondrion , nitric oxide , reactive nitrogen species , chemistry , superoxide , microbiology and biotechnology , in vivo , biochemistry , mitochondrial ros , biology , in vitro , enzyme , organic chemistry , gene
The synthetic immunomodulator muramyl dipeptide (MDP) has been shown to induce, in vivo , mitochondrial proton leak. In the present work, we extended these findings to the cellular level and confirmed the effects of MDP in vitro on murine macrophages. The macrophage system was then used to analyse the mechanism of the MDP‐induced mitochondrial proton leak. Our results demonstrate that the cellular levels of superoxide anion and nitric oxide were significantly elevated in response to MDP. Moreover, isolated mitochondria from cells treated with MDP presented a significant decrease in respiratory control ratio, an effect that was absent following treatment with a non‐toxic analogue such as murabutide. Stimulation of cells with MDP, but not with murabutide, rapidly upregulates the expression of the mitochondrial protein uncoupling protein 2 (UCP2), and pretreatment with vitamin E attenuates upregulation of UCP2. These findings suggest that the MDP‐induced reactive species upregulate UCP2 expression in order to counteract the effects of MDP on mitochondrial respiratory efficiency.