Dynamics of cytochrome c oxidase activity in acute ischemic stroke

Carbon monoxide (CO) modulates hydrogen peroxide (H2O2)-mediated cellular dysfunction by targeting mitochondria in rabbit lens epithelial cells

Mitochondrial components are of great importance for the maintenance of lens transparency. In our previous work, we confirmed that carbon monoxide (CO) can protect human and rabbit lens epithelial cells (LECs) from hydrogen peroxide (H₂O₂)-mediated apoptosis, while the mechanism remains undefined. Because CO can bind to mitochondrial cytochrome c oxidase (COX), we evaluated the effect of CO on the regulation of mitochondrial biogenesis and function in H₂O₂-treated rabbit LECs. To evaluate mitochondrial biogenesis, several mitochondrial transcription factors (PGC-1α, NRF-1, and mtTFA) were detected by western blot analysis. To assess cellular metabolism, adenosine triphosphate (ATP) levels and COX enzymatic activity were measured. In addition, mitochondrial permeability transition pores (mPTP) opening, dissipation of mitochondrial membrane potential (ΔΨm), cytochrome c mitochondrial translocation, and apoptotic molecules were also detected to evaluate mitochondrial apoptosis pathway. Furthermore, the interaction of Bcl-2 and COX was assessed by co-immunoprecipitation. Finally, CO-mediated regulation of cellular function was detected in Bcl-2-knockdown cells. Our results confirmed that CO pretreatment restored H₂O₂-induced down-regulation of mitochondrial transcription factors expression, COX activity and ATP production. Moreover, CO pretreatment attenuated mPTP opening, ΔΨm loss, cytochrome c mitochondrial translocation, and activation of apoptotic molecules. Bcl-2 was identified to bind to COX, and silence of Bcl-2 expression prevented CO-regulated cellular metabolism and cytoprotection. These data suggest that CO modulates H₂O₂-induced cellular dysfunction by increasing mitochondrial biogenesis, enhancing cellular metabolism, and attenuating mitochondrial apoptosis cascade. Moreover, Bcl-2 expression was vital for CO to regulate cellular metabolism and cytoprotection in LECs.

Retraction statement: Dynamics of Cytochrome C Oxidase Activity in Acute Ischemic Stroke' by Selaković, V.M., Jovanović, M.D., Mihajlović, R.R. and Radenović, L.L.J

The above article from Acta Neurologica Scandinavica, published online on 7 April 2005 in Wiley Online Library (wileyonlinelibrary.com) and in Volume 111, pp. 329-332, has been retracted by agreement between the journal Editor in Chief, Professor Elinor Ben-Menachem, and John Wiley & Sons Ltd. The article has been retracted because a similar article had previously been published in the Jugoslovenska medicinska biohemija in 2003. The authors presumed that since the journal was no longer existing, they felt the need to re-publish their work in Acta Neuorologica Scandinavica. However, in the consideration of the Journal, this constitutes dual publication. References SelakovićVM, JovanovićMD, MihajlovićR, RadenovićLLJ. Cytochrome c oxidase in patients with acute ischaemic brain disease. Jugoslovenska medicinska biohemija. 2003;22:329-334. SelakovićVM, JovanovićMD, MihajlovićRR, RadenovićLLJ. Dynamics of cytochrome c oxidase activity in acute ischemic stroke. Acta Neurol Scand. 2005;111:329-332.

Mitochondrial Impairment in Cerebrovascular Endothelial Cells is Involved in the Correlation between Body Temperature and Stroke Severity

Stroke is the second leading cause of death worldwide. The prognostic influence of body temperature on acute stroke in patients has been recently reported; however, hypothermia has confounded experimental results in animal stroke models. This work aimed to investigate how body temperature could prognose stroke severity as well as reveal a possible mitochondrial mechanism in the association of body temperature and stroke severity. Lipopolysaccharide (LPS) compromises mitochondrial oxidative phosphorylation in cerebrovascular endothelial cells (CVECs) and worsens murine experimental stroke. In this study, we report that LPS (0.1 mg/kg) exacerbates stroke infarction and neurological deficits, in the mean time LPS causes temporary hypothermia in the hyperacute stage during 6 hours post-stroke. Lower body temperature is associated with worse infarction and higher neurological deficit score in the LPS-stroke study. However, warming of the LPS-stroke mice compromises animal survival. Furthermore, a high dose of LPS (2 mg/kg) worsens neurological deficits, but causes persistent severe hypothermia that conceals the LPS exacerbation of stroke infarction. Mitochondrial respiratory chain complex I inhibitor, rotenone, replicates the data profile of the LPS-stroke study. Moreover, we have confirmed that rotenone compromises mitochondrial oxidative phosphorylation in CVECs. Lastly, the pooled data analyses of a large sample size (n=353) demonstrate that stroke mice have lower body temperature compared to sham mice within 6 hours post-surgery; the body temperature is significantly correlated with stroke outcomes; linear regression shows that lower body temperature is significantly associated with higher neurological scores and larger infarct volume. We conclude that post-stroke body temperature predicts stroke severity and mitochondrial impairment in CVECs plays a pivotal role in this hypothermic response. These novel findings suggest that body temperature is prognostic for stroke severity in experimental stroke animal models and may have translational significance for clinical stroke patients - targeting endothelial mitochondria may be a clinically useful approach for stroke therapy.

Decreased cerebrospinal fluid cytochrome c levels in patients with amyotrophic lateral sclerosis

OBJECTIVE

There is evidence showing impaired mitochondrial energy production and increased oxidative damage to mitochondria in amyotrophic lateral sclerosis (ALS). It is known that a lack of cytochrome c (CyC) in the mitochondrial intermembrane space can increase free radical release from mitochondria through interruption of the electron transport. CyC also plays a role in the apoptotic cell death which is suspected in ALS. The aim of the study was to measure cerebrospinal fluid (CSF) and serum CyC levels in patients with ALS.

MATERIAL AND METHODS

Forty ALS patients were diagnosed according to the El Escorial criteria of ALS. The clinical state of the patients was measured using the Amyotrophic Lateral Sclerosis Functional Rating Scale [ALSFRS].

RESULTS

It was shown that overall CyC levels were significantly decreased by 46 % in the CSF of patients with ALS compared with controls (p<0.05), and not affected in serum of patients with ALS (p>0.05). There was no significant difference in CyC levels in relation to the clinical parameters of the disease (p>0.05).

CONCLUSIONS

The study indicates that CyC may play a role in the pathogenesis of ALS. A possible mechanism is that increased neurodegeneration in ALS caused by free radical production decreases the concentrations of CyC.