Mitochondrial Reactive Oxygen Species in Mice Lacking Superoxide Dismutase 2

Abstract

. resulting from complex II normalization had no effect on steady state levels due to the rapid conversion to H 2 O 2 , a process presumably aided by the presence of the EUK189, an SOD mimetic.Age-related diseases, including cancer, type 2 diabetes, and Alzheimer and Parkinson diseases, show a clear correlation with mitochondrial dysfunction and reactive oxygen species (ROS) 3 (5-12). Tissues with high energy expenditure such as brain, heart, muscle, and pancreas have significant ATP requirements. The vast majority of such ATP is derived from mitochondrial oxidative phosphorylation, a series of sequential electron transfers along the respiratory chain resulting in the reduction of O 2 to water concomitant with the production of ATP. During the course of normal respiration under state IV conditions, as much as 0.4 -4% (13-15) of all oxygen consumed can be converted into the free radical superoxide, which in turn can be converted to other ROS, although physiological levels may be dependent on age, tissue, and cell type. The majority of mitochondrial superoxide is generated from two respiratory chain complexes, complex I and complex III (16), the former producing superoxide on the matrix side of the mitochondrial membrane and the latter liberating superoxide both to the matrix side and into the intermembrane space (17)(18)(19)(20). The relative importance of the two sites in mitochondrial superoxide production is currently an area of debate (19,21). When electrons are passed from succinate to NAD via energy-dependent reverse electron flow, complex I produces ROS at relatively high rates (14,15,17,(21)(22)(23). During forward electron flow both complexes produce ROS at very low rates unless respiratory chain inhibitors such as the complex I inhibitor rotenone or the complex III inhibitor antimycin A are present (20,24). The potential consequences of this endogenously produced ROS upon mammalian physiology became clearer with the creation of superoxide dismutase null mice.

Mitochondrial Respiratory Enzyme Complexes in Rostral Ventrolateral Medulla as Cellular Targets of Nitric Oxide and Superoxide Interaction in the Antagonism of Antihypertensive Action of eNOS Transgene

“…Mitochondria isolated from sod2-null mice exhibit higher levels of mitochondrial O 2 . than the wild type, of which is attenuated by a SOD mimetic (Morten et al, 2006). The present results further showed that gene transduction of SOD2 to the RVLM resulted in depressor responses in SHR.…”

Tissue-specific splicing of an Ndufs6 gene-trap insertion generates a mitochondrial complex I deficiency-specific cardiomyopathy

“…microplate reader (BMG Labtechnologies). ROS production (H 2 O 2 ) in live mitochondria (25 μg/mL) was assessed using the fluorescent probe Amplex Red via the protocol of Morten et al with minor modifications (38). H 2 O 2 production was measured fluorometrically (excitation 540 nm, emission 590 nm) over a 20-min period on a FLUOstar OPTIMA microplate reader.…”

Mitochondrial disruption occurs downstream from β-adrenergic overactivation by isoproterenol in differentiated, but not undifferentiated H9c2 cardiomyoblasts: Differential activation of stress and survival pathways

“…We analyzed three mitochondrial proteins that have an important role on mitochondrial survival/death decisions, including SOD2, the manganese superoxide dismutase isoform (Morten et al, 2006), cyclophilin F (also often described as cyclophilin D) a matrix chaperone involved in the mitochondrial permeability transition (Di Lisa et al, 2011) and Bcl-xL, a Bcl-2 family protein, which inhibits mitochondrial-mediated cell death (Ogata and Takahashi, 2003). The data now obtained shows that ISO, when incubated with H9c2 cells in different stages of differentiation causes an up-regulation of all three proteins in the undifferentiated cell group, while the content in Bcl-xL decreases in the RAdifferentiated group (Fig.…”