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Ca2+‐Dependent S‐glutathionylation Mediates Intermittent Hypoxia–Induced Mitochondrial Complex I Inhibition
Author(s) -
Khan Shakil Ahmad,
Yuan Guoxiang,
Kumar Ganesh K,
Prabhakar Nanduri R
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.669.24
Subject(s) - hypoxia (environmental) , chemistry , microbiology and biotechnology , biophysics , biology , oxygen , organic chemistry
In the present study we tested the hypothesis that ROS generated by NADPH oxidase (Nox) elevates Ca 2+ levels and the resulting Ca 2+ entry into mitochondria inhibits complex I. Experiments were performed on IH‐treated cell cultures and in mice deficient in Nox function. BAPTA‐AM, a Ca 2+ chelator or ruthenium red, an inhibitor of mitochondrial Ca 2+ uniporter, prevented IH‐induced complex I inhibition. Ca 2+ reduced the affinity of complex1 to NADH (substrate) during IH as evidenced by decreased V max and K m . IH increased S‐glutathionylation (red‐ox modification) of 75 and 50 kDa subunits of the complex I in a Ca 2+ ‐dependent manner. IH‐evoked S‐glutathionylation was due to elevated GSSG as evidenced by increased ratio of GSSG/GSH. Addition of GSH during IH abrogated complex I inhibition. IH‐evoked glutathionylation was prevented by a Nox inhibitor as well as by genetic silencing of Nox 2 in cell cultures and was absent in IH‐treated Nox2 KO mice. These observations suggest that ROS generated by Nox mobilizes Ca 2+ from the cytosol to mitochondria, leading to S‐glutathionylation of 75‐ and 50‐kDa proteins of the complex I resulting in inhibition of its activity. Supported by HL‐90554, HL‐76537, HL‐86493 and HL‐89616.