NDUFA4 Is a Subunit of Complex IV of the Mammalian Electron Transport Chain

SummaryChanges in mitochondrial function with age vary between different muscle types, and mechanisms underlying this variation remain poorly defined. We examined whether the rate of mitochondrial protein turnover contributes to this variation. Using heavy label proteomics, we measured mitochondrial protein turnover and abundance in slow‐twitch soleus (SOL) and fast‐twitch extensor digitorum longus (EDL) from young and aged mice. We found that mitochondrial proteins were longer lived in EDL than SOL at both ages. Proteomic analyses revealed that age‐induced changes in protein abundance differed between EDL and SOL with the largest change being increased mitochondrial respiratory protein content in EDL. To determine how altered mitochondrial proteomics affect function, we measured respiratory capacity in permeabilized SOL and EDL. The increased mitochondrial protein content in aged EDL resulted in reduced complex I respiratory efficiency in addition to increased complex I‐derived H2O2 production. In contrast, SOL maintained mitochondrial quality, but demonstrated reduced respiratory capacity with age. Thus, the decline in mitochondrial quality with age in EDL was associated with slower protein turnover throughout life that may contribute to the greater decline in mitochondrial dysfunction in this muscle. Furthermore, mitochondrial‐targeted catalase protected respiratory function with age suggesting a causal role of oxidative stress. Our data clearly indicate divergent effects of age between different skeletal muscles on mitochondrial protein homeostasis and function with the greatest differences related to complex I. These results show the importance of tissue‐specific changes in the interaction between dysregulation of respiratory protein expression, oxidative stress, and mitochondrial function with age.

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“…* NDUFA 4, traditionally associated with complex I, may be associated instead with complex IV (Balsa et al . 2012). n.d. = not detected.…”

Section: Resultsmentioning

confidence: 99%

Age modifies respiratory complex I and protein homeostasis in a muscle type‐specific manner

et al. 2015

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“…The mitochondrial NADH: ubiquinone oxidoreductase complex I is a key determinant in steadystate ROS production. This 1 MDa complex, composed of 44 subunits, 14 couples the transfer of two electrons from NADH to ubiquinone with the translocation of four protons to generate the ΔΨm. The importance of ROS has been previously demonstrated for caspase-3 and granzyme A (GA) pathways through the cleavage of NDUFS1 and NDUFS3, respectively.…”

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confidence: 99%

Granzyme B-induced mitochondrial ROS are required for apoptosis

et al. 2014

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Caspases and the cytotoxic lymphocyte protease granzyme B (GB) induce reactive oxygen species (ROS) formation, loss of transmembrane potential and mitochondrial outer membrane permeabilization (MOMP). Whether ROS are required for GBmediated apoptosis and how GB induces ROS is unclear. Here, we found that GB induces cell death in an ROS-dependent manner, independently of caspases and MOMP. GB triggers ROS increase in target cell by directly attacking the mitochondria to cleave NDUFV1, NDUFS1 and NDUFS2 subunits of the NADH: ubiquinone oxidoreductase complex I inside mitochondria. This leads to mitocentric ROS production, loss of complex I and III activity, disorganization of the respiratory chain, impaired mitochondrial respiration and loss of the mitochondrial cristae junctions. Furthermore, we have also found that GB-induced mitocentric ROS are necessary for optimal apoptogenic factor release, rapid DNA fragmentation and lysosomal rupture. Interestingly, scavenging the ROS delays and reduces many of the features of GB-induced death. Consequently, GB-induced ROS significantly promote apoptosis. Cell Death and Differentiation (2015) 22, 862-874; doi:10.1038/cdd.2014.180; published online 31 October 2014To induce cell death, human granzyme B (GB) activates effector caspase-3 or acts directly on key caspase substrates, such as the proapoptotic BH3 only Bcl-2 family member Bid, inhibitor of caspase-activated DNase (ICAD), poly-(ADPribose) polymerase-1 (PARP-1), lamin B, nuclear mitotic apparatus protein 1 (NUMA1), catalytic subunit of the DNAdependent protein kinase (DNA-PKcs) and tubulin. [1][2][3] Consequently, caspase inhibitors have little effect on human GB-mediated cell death and DNA fragmentation. 2 GB causes reactive oxygen species (ROS) production, dissipation of the mitochondrial transmembrane potential (ΔΨm) and MOMP, which leads to the release of apoptogenic factors such as cytochrome c (Cyt c), HtrA2/Omi, endonuclease G (Endo G), Smac/Diablo and apoptosis-inducing factor, from the mitochondrial intermembrane space to the cytosol. [4][5][6][7][8][9][10][11] Interestingly, cells deficient for Bid, Bax and Bak are still sensitive to human GB-induced cell death, 5,11-13 suggesting that human GB targets the mitochondria in another way that needs to be characterized. Altogether, much attention has been focused on the importance of MOMP in the execution of GB-mediated cell death, leaving unclear whether ROS production is a bystander effect or essential to the execution of GBinduced apoptosis. The mitochondrial NADH: ubiquinone oxidoreductase complex I is a key determinant in steadystate ROS production. This 1 MDa complex, composed of 44 subunits, 14 couples the transfer of two electrons from NADH to ubiquinone with the translocation of four protons to generate the ΔΨm. The importance of ROS has been previously demonstrated for caspase-3 and granzyme A (GA) pathways through the cleavage of NDUFS1 and NDUFS3, respectively. [15][16][17][18] GA induces cell death in a Bcl-2-insensitive and caspase-and MOMP-indepen...

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“…For each two electrons transferred from NADH to ubiquinone, four protons are ejected from the mitochondrial matrix, thereby contributing to the proton motive force across the inner membrane (1). The mammalian enzyme has 44 subunits, with a combined molecular mass of about 1 MDa, assembled into an L-shaped complex, with one arm embedded in the inner membrane and the other protruding into the matrix of the organelle (2)(3)(4). Seven hydrophobic subunits (ND1-ND6 and ND4L) of the membrane arm of NADH dehydrogenase (complex I) are encoded in mitochondrial DNA, and synthesized on mitochondrial ribosomes (5).…”

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confidence: 99%

Assembly factors for the membrane arm of human complex I

Andrews

Carroll

Ding

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

132

125

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Mitochondrial respiratory complex I is a product of both the nuclear and mitochondrial genomes. The integration of seven subunits encoded in mitochondrial DNA into the inner membrane, their association with 14 nuclear-encoded membrane subunits, the construction of the extrinsic arm from 23 additional nuclear-encoded proteins, iron-sulfur clusters, and flavin mononucleotide cofactor require the participation of assembly factors. Some are intrinsic to the complex, whereas others participate transiently. The suppression of the expression of the NDUFA11 subunit of complex I disrupted the assembly of the complex, and subcomplexes with masses of 550 and 815 kDa accumulated. Eight of the known extrinsic assembly factors plus a hydrophobic protein, C3orf1, were associated with the subcomplexes. The characteristics of C3orf1, of another assembly factor, TMEM126B, and of NDUFA11 suggest that they all participate in constructing the membrane arm of complex I. mitochondria | respiratory chain | NADH:ubiquinone oxidoreductase

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NDUFA4 Is a Subunit of Complex IV of the Mammalian Electron Transport Chain

Cited by 336 publications

References 38 publications

Age modifies respiratory complex I and protein homeostasis in a muscle type‐specific manner

Age modifies respiratory complex I and protein homeostasis in a muscle type‐specific manner

Granzyme B-induced mitochondrial ROS are required for apoptosis

Assembly factors for the membrane arm of human complex I

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