Ethanol withdrawal posttranslationally decreases the activity of cytochrome c oxidase in an estrogen reversible manner

Cytochrome c oxidase (COX) is a key mitochondrial enzyme that catalyzes electron transfer at the terminal stage of respiratory chain and is composed of multisubunits. We hypothesize that ethanol withdrawal (EW) impairs the activity of COX and estrogen deprivation exacerbates this problem. Five-month-old ovariectomized rats with or without 17beta-estradiol (E2) replacement received a control dextrin or a liquid ethanol diet (6.5%, 5 weeks). They were then sacrificed either during ethanol exposure or at 24h of EW (EW group). Mitochondria of the cerebellum and cortex were processed to measure the activities of total COX, COX subunit I, and IV. The effects of EW and E2 on the protein levels of these subunits were also assessed using an immunoblotting method. As compared to the control dextrin and ethanol exposure, EW decreased the activities of total COX, COX I, and COX IV. E2 treatment prevented the effects of EW on the activities of total COX and COX IV but not COX I. Neither EW nor E2 altered the protein levels of the subunits. These findings suggest that a counteracting relationship exists between the effects of EW and E2 on the activity of COX in a subunit specific manner.     

Ethanol withdrawal acts as an age-specific stressor to activate cerebellar P38 kinase

We investigated whether protein kinase P38 plays a role in the brain-aging changes associated with repeated ethanol withdrawal (EW). Ovariectomized young, middle-age and older rats, with or without 17β-estradiol (E2) implantation, received a 90-day ethanol with repeated withdrawal. They were tested for active pP38 expression in cerebellar Purkinje neurons and whole-cerebellar lysates using immunohistochemistry and enzyme-linked immunosorbent assay, respectively. They were also tested for the Rotarod task to determine the behavioral manifestation of cerebellar neuronal stress and for reactive oxygen species (ROS) and mitochondrial protein carbonyls to determine oxidative mechanisms. Middle-age EW rats showed higher levels of pP38-positive Purkinje neurons/cerebellar lysates, which coincided with increased mitochondrial protein oxidation than other diet/age groups. Exacerbated motor deficit due to age–EW combination also began at the middle-age. In comparison, ROS contents peaked in older EW rats. E2 treatment mitigated each of the EW effects to a different extent. Collectively, pP38 may mediate the brain-aging changes associated with pro-oxidant EW at vulnerable ages and in vulnerable neurons in a manner protected by estrogen.     

Mitochondrial copper metabolism in yeast: mutational analysis of Sco1p involved in the biogenesis of cytochrome c oxidase

Saccharomyces cerevisiae Sco1p is believed to be involved in the transfer of copper from the carrier Cox17p to the mitochondrial cytochrome c oxidase subunits 1 and 2. We here report on the results of a mutational analysis of Sco1p. The two cysteine residues of a potential metal-binding motif (CxxxC) are essential for protein function as shown by their substitution by alanines. Chimeras consisting of Sco1p and its homolog S. cerevisiae Sco2p restrict the specificity of Sco1p function to the N-terminal half of the protein. A candidate region for conferring specificity on Sco1p is a stretch of hydrophobic amino acids, which act as a membrane anchor. In line with this suggestion is the result that alterations of individual amino acids within this region impair Sco1p function. Received: 30 October / 10 December 1998     

Primary structure of a gene for subunit V of the cytochrome c oxidase from Saccharomyces cerevisiae

Summary We have isolated a gene coding for cytochrome c oxidase subunit V by genetic complementation in yeast. This protein is made as a 153 amino acid long precursor; its amino-terminal extension of 20 amino acids contains four basic residues and no acidic one, a feature common to most pre-sequences of imported mitochondrial proteins.     

Endurance training increases the expression of mitochondrial and nuclear encoded cytochrome c oxidase subunits and heat shock proteins in rat skeletal muscle

Cytochrome c oxidase (CCO) is an enzyme complex found on the inner mitochondrial membrane and serves as the final electron acceptor in mitochondrial electron transport. Heat shock proteins (HSPs) are involved in the import of nuclear encoded protein subunits into the mitochondria and induce conformational changes to form active enzyme complexes. As both the nuclear and mitochondrial encoded subunits of CCO have been shown to increase in activity and expression in muscle subsequent to artificial loading, and as exercise has been shown to induce HSPs, we sought to determine whether 16–20 weeks of treadmill exercise would result in enhanced CCO subunit expression, and to determine if there was a relationship between this expression and HSP content in medial gastrocnemius muscle of Fischer 344 rats. Our results indicated that endurance training resulted in a 53%, 87% and 80% increase (P < 0.05) in the levels of HSP 60, CCO subunit II and CCO subunit VI, respectively. Enzymatic activity of CCO was 84% greater (P < 0.05) after endurance training. Mann Whitney U analyses showed that CCO subunit II and VI increased to the same extent as HSP 60 after endurance training. It appears that 16–20 weeks of endurance training leads to uniform increases in CCO subunits and parts of the transport and assembly mechanisms required for CCO enzyme assembly. The similarity among the increases in CCO subunits II and VI protein levels and the increase in CCO enzyme activity suggest that this increase in activity is due to an increase in the amount of CCO enzyme. Accepted: 26 April 2000     

Insight into the role of TSLP in inflammatory bowel diseases

Proinflammatory cytokines are thought to modulate pathogeneses of various inflammatory bowel diseases (IBDs). Thymic stromal lymphopoietin (TSLP), which has been studied in various allergic diseases such as asthma, atopic dermatitis (AD) and eosinophilic esophagitis (EoE), has been less considered to be involved in IBDs. However, mucosal dendritic cells (DCs) induced by various cytokines including TSLP were reported to cause polarization of T cell toward Th2 response, the differentiation of regulatory T-cell (Treg), and secretion of IgA by B cells. In this review, we discuss the concept that decreased TSLP has the potential to accelerate the development of Th1 response dominant diseases such as the Crohn's disease (CD) while increased TSLP has the potential to lead to a development of Th2 cell dominant diseases such the ulcerative colitis (UC). To examine TSLP's role as a potential determining factor for differentiating UC and CD, we analyzed the effects of other genes regulated by TSLP in regards to the UC and CD pathogeneses using data from online open access resources such as NetPath, GeneMania, and the String database. Our findings indicate that TSLP is a key mediator in the pathogenesis of IBDs and that further studies are needed to evaluate its role.