Signal Tansduction and Gene Expression 1 Mitochondrial Superoxide Mimics the Cellular Response To Nutrients in the Yeast Saccharomyces cerevisiae Allen Baron1, and Valeria Culotta1 1Johns Hopkins University The yeast, Saccharomyces cerevisiae, regulates the pH of its environment in order to signal changes in nutrient availability to neighboring cells. When nutrients are readily available yeast acidify their surrounding environment, promoting cell growth, whereas when nutrients are limiting their environment becomes basic, leading to growth arrest. We find that this complex response to nutrients involves changes in cellular production of acetate and to a lesser extent succinate. Moreover, under conditions of nutrient starvation superoxide produced in mitochondria or disruption of the TCA cycle triggers a response similar to that of cells in a nutrient rich environment. These findings implicate mitochondrial superoxide and TCA cycle metabolites in the cellular response to nutrients.

doi : 10.1016/j.freeradbiomed.2011.10.023

2 Carnosine Induces Expression of Transcriptional Factors in Cultured Neurons Which Increase Neuronal Viability Under Oxidative Stress Alexander a Boldyrev1,2, Irina S Dobrotvorskaya3, Maria S Stepanova2, and Temirbulat T Berezov3 1Moscow State University, Dept of Biochemistry, 2Research Center of Neurology, 3Institute of Biomedical Chemistry Expression of many transcriptional factors is regulated by redox state of the cells which is especially important for neurons because of their inclination to oxidative stress. It is clear now that activation of some neuronal genes may result in induction of apoptosis (Son et al, 2011). Neuropeptide carnosine is natural dipeptide protecting neurons from several kinds of oxidative stress (Boldyrev, 2006). From common point of view, its effect is related to known antioxidant properties restricting accumulation of reactive oxygen species (ROS) and their damaging action of cell components. in this study we have shown that carnosine at concentrations corresponding to its content in mammalian brain affects expression a number of genes which activity directly relates to cell viability. Experiments were done using cultured rat cerebellum cells. Oxidative stress was induced by incubation of cells with homocysteic acid (HCA), stable congener of homocysteine (HC) both being ligands specifically stimulated glutamate receptors of NMDA class. in order to identify molecular mechanism of cytotoxic action of HCA/HC and to estimate possible protective action of carnosine we incubated the neurons with 0.5 mM HCA during 5 hr which resulted in ROS accumulation and up-regulation of mRNA for NF-kB and bax. Incubation of neurons with HCA and carnosine (5 mM) simultaneously provoked up-regulations of mRNA for MnSOD and for bcl-2. Carnosine added to cultural medium 30 min before HCA decreased ROS levels and prevented both apoptotic and necrotic neuronal death. Moreover, carnosine increased bcl-2/bax ratio and down-regulated NF-kB expression in cerebellum granule cells. the data obtained demonstrate that HCA alters expression of at least two transcriptional factors, NF-kB and bax which results in apoptosis initiation. Carnosine stimulates expression of MnSOD

and anti-apoptotic protein bcl-2, as well as suppresses NF-kB expression. This explains its protective effect on cerebellum cells under oxidative stress conditions. These results reveal molecular basis for brain protection by carnosine which is described earlier under in vivo conditions (Dobrota et al, 2010; Boldyrev et al, 2011). The study was supported by RFBR (## 09-04-00507 and 11-04-00906).

doi : 10.1016/j.freeradbiomed.2011.10.024

3 Nrf1 (NFE2L1) Transcription Factor is Regulated by Multiple Stimuli Through the Stability of its Inhibitory P65 Nrf1 Form Nikolai Leonidovitch Chepelev1, Joshua D. Bennitz2, Ting Huang3, Skye McBride1, Hongqiao Zhang4, Honglei Liu4, Kelvin J. A. Davies5, Henry Jay Forman4, and William Glen Willmore1 1Carleton University, Ottawa, Canada, 2University of Toronto, 3McGill University, 4University of California, Merced, 5University of Southern California, LA Nrf1 (NF-E2-related factor 1 or NFE2L1) mediates the expression of multiple antioxidant and cytoprotective genes, containing the electrophile response element (EpRE) in their promoters. Unlike its more thoroughly-studied, CNC-bZIP (cap’n’collar basic Leu zipper) transcription factor subfamily member Nrf2 (NFE2L2), that is regulated through rapid proteasomal degradation, mediated by Keap1, the mechanisms controlling Nrf1 activity are enigmatic. What is currently known is that the full-length Nrf1 form is bound to the endoplasmic reticulum (ER) through its N-terminal domain, that Nrf1 translocates from the ER to the nucleus upon certain stimuli and that Nrf1 appears to be regulated independently of Keap1. Besides the association with the ER membrane, another unique feature of Nrf1 compared to Nrf2 is the existence of the short form of Nrf1, termed “p65 Nrf1”, arising through either proteolysis or internal translation. While the p65 Nrf1 has been reported to act as a dominant negative inhibitor of the Nrf2/EpRE-mediated gene expression (J Biol Chem. 282:24670-8, 2007), the reports on the significance of the p65 Nrf1 in regulating the EpRE-driven gene expression are lacking. Using cultured mammalian cells, we noted that the activation of the EpRE gene expression by either low oxygen or bisphenol a was accompanied by marked reduction in the p65 Nrf1 protein expression. in addition, we observed significant stabilization of the p65 Nrf1 in aged (21-month compared to six-month old) mice with accompanying decreases in the Nrf2 nuclear presence and Nrf2 DNA-binding function in aged animals. These results suggest that p65 Nrf1 can provide an extra regulatory feature to manage the Nrf2-dependent EpRE gene expression under several physiologically-relevant conditions.

doi : 10.1016/j.freeradbiomed.2011.10.025

4 PGC-1α and the Mitochondrial Antioxidant Response during Sepsis Anne D Cherry1, Raquel R Bartz1, Ping Fu1, Claude a Piantadosi1, and Hagir B Suliman1 1Duke University Medical Center Introduction: Sepsis-induced oxidative stress causes significant mitochondrial damage and mitochondrial biogenesis is required to maintain respiratory capacity. Mitochondrial biogenesis and

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