Effects of Long-Term Space Flight on Erythrocytes and Oxidative Stress of Rodents

Erythrocyte and hemoglobin losses have been frequently observed in humans during space missions; these observations have been designated as “space anemia”. Erythrocytes exposed to microgravity have a modified rheology and undergo hemolysis to a greater extent. Cell membrane composition plays an important role in determining erythrocyte resistance to mechanical stress and it is well known that membrane composition might be influenced by external events, such as hypothermia, hypoxia or gravitational strength variations. Moreover, an altered cell membrane composition, in particular in fatty acids, can cause a greater sensitivity to peroxidative stress, with increase in membrane fragility. Solar radiation or low wavelength electromagnetic radiations (such as gamma rays) from the Earth or the space environment can split water to generate the hydroxyl radical, very reactive at the site of its formation, which can initiate chain reactions leading to lipid peroxidation. These reactive free radicals can react with the non-radical molecules, leading to oxidative damage of lipids, proteins and DNA, etiologically associated with various diseases and morbidities such as cancer, cell degeneration, and inflammation. Indeed, radiation constitutes on of the most important hazard for humans during long-term space flights. With this background, we participated to the MDS tissue-sharing program performing analyses on mice erythrocytes flown on the ISS from August to November 2009. Our results indicate that space flight induced modifications in cell membrane composition and increase of lipid peroxidation products, in mouse erythrocytes. Moreover, antioxidant defenses in the flight erythrocytes were induced, with a significant increase of glutathione content as compared to both vivarium and ground control erythrocytes. Nonetheless, this induction was not sufficient to prevent damages caused by oxidative stress. Future experiments should provide information helpful to reduce the effects of oxidative stress exposure and space anemia, possibly by integrating appropriate dietary elements and natural compounds that could act as antioxidants

Hepatoprotection and neuroprotection induced by low doses of IGF-II in aging rats

<p>Abstract</p> <p>Background</p> <p>GH and IGFs serum levels decline with age. Age-related changes appear to be associated to decreases in these anabolic hormones. We have previously demonstrated that IGF-I replacement therapy improves insulin resistance, lipid metabolism and reduces oxidative damage (in brain and liver) in aging rats. Using the same experimental model, the aim of this work was to study whether the exogenous administration of IGF-II, at low doses, acts analogous to IGF-I in aging rats.</p> <p>Methods</p> <p>Three experimental groups were included in this study: young healthy controls (yCO, 17 weeks old); untreated old rats (O, 103 weeks old); and aging rats treated with IGF-II (O+IGF-II, 2 μg * 100 g body weight^-1* day^-1) for 30 days. Analytical parameters were determined in serum by routine laboratory methods using an autoanalyzer (Cobas Mira; Roche Diagnostic System, Basel, Switzerland). Serum levels of hormones (testosterone, IGF-I and insulin) were assessed by RIA. Serum Total Antioxidant Status was evaluated using a colorimetric assay. Mitochondrial membrane potential was evaluated using rhodamine 123 dye (adding different substrates to determine the different states). ATP synthesis in isolated mitochondria was determined by an enzymatic method.</p> <p>Results</p> <p>Compared with young controls, untreated old rats showed a reduction of IGF-I and testosterone levels with a decrease of serum total antioxidant status (TAS). IGF-II therapy improved serum antioxidant capability without modifying testosterone and IGF-I circulating concentrations. In addition, IGF-II treatment reduced oxidative damage in brain and liver, improving antioxidant enzyme activities and mitochondrial function. IGF-II was also able to reduce cholesterol and triglycerides levels increasing free fatty acids concentrations.</p> <p>Conclusions</p> <p>We demonstrate that low doses of IGF-II induce hepatoprotective, neuroprotective and metabolic effects, improving mitochondrial function, without affecting testosterone and IGF-I levels.</p

Biogenesis of the Signal Recognition Particle (Srp) Involves Import of Srp Proteins into the Nucleolus, Assembly with the Srp-Rna, and Xpo1p-Mediated Export

The signal recognition particle (SRP) targets nascent secretory proteins to the ER, but how and where the SRP assembles is largely unknown. Here we analyze the biogenesis of yeast SRP, which consists of an RNA molecule (scR1) and six proteins, by localizing all its components. Although scR1 is cytoplasmic in wild-type cells, nuclear localization was observed in cells lacking any one of the four SRP “core proteins” Srp14p, Srp21p, Srp68p, or Srp72p. Consistently, a major nucleolar pool was detected for these proteins. Sec65p, on the other hand, was found in both the nucleoplasm and the nucleolus, whereas Srp54p was predominantly cytoplasmic. Import of the core proteins into the nucleolus requires the ribosomal protein import receptors Pse1p and Kap123p/Yrb4p, which might, thus, constitute a nucleolar import pathway. Nuclear export of scR1 is mediated by the nuclear export signal receptor Xpo1p, is distinct from mRNA transport, and requires, as evidenced by the nucleolar accumulation of scR1 in a dis3/rrp44 exosome component mutant, an intact scR1 3′ end. A subset of nucleoporins, including Nsp1p and Nup159p (Rat7p), are also necessary for efficient translocation of scR1 from the nucleus to the cytoplasm. We propose that assembly of the SRP requires import of all SRP core proteins into the nucleolus, where they assemble into a pre-SRP with scR1. This particle can then be targeted to the nuclear pores and is subsequently exported to the cytoplasm in an Xpo1p-dependent way

Enhancing Drug Discovery and Development through the Integration of Medicinal Chemistry, Chemical Biology, and Academia-Industry Partnerships: Insights from Roche’s Endocannabinoid System Projects

: The endocannabinoid system (ECS) is a critical regulatory network composed of endogenous cannabinoids (eCBs), their synthesizing and degrading enzymes, and associated receptors. It is integral to maintaining homeostasis and orchestrating key functions within the central nervous and immune systems. Given its therapeutic significance, we have launched a series of drug discovery endeavors aimed at ECS targets, including peroxisome proliferator-activated receptors (PPARs), cannabinoid receptors types 1 (CB1R) and 2 (CB2R), and monoacylglycerol lipase (MAGL), addressing a wide array of medical needs. The pursuit of new therapeutic agents has been enhanced by the creation of specialized labeled chemical probes, which aid in target localization, mechanistic studies, assay development, and the establishment of biomarkers for target engagement. By fusing medicinal chemistry with chemical biology in a comprehensive, translational end-to-end drug discovery strategy, we have expedited the development of novel therapeutics. Additionally, this strategy promises to foster highly productive partnerships between industry and academia, as will be illustrated through various examples

Chromium Stress Mitigation by Polyamine-Brassinosteroid Application Involves Phytohormonal and Physiological Strategies in Raphanus sativus L.

Brassinosteroids (BRs) and polyamines (PAs) are well-established growth regulators playing key roles in stress management among plants. In the present study, we evaluated the effects of epibrassinolide (EBL, an active BR) and spermidine (Spd, an active PA) on the tolerance of radish to oxidative stress induced by Cr (VI) metal. Our investigation aimed to study the impacts of EBL (10−9 M) and/or Spd (1 mM) on the biochemical and physiological responses of radish (Raphanus sativus L.) under Cr-stress. Applications of EBL and/or Spd were found to improve growth of Cr-stressed seedlings in terms of root length, shoot length and fresh weight. Our data also indicated that applications of EBL and Spd have significant impacts, particularly when applied together, on the endogenous titers of PAs, free and bound forms of IAA and ABA in seedlings treated with Cr-stress. Additionally, co-applications of EBL and Spd modulated more remarkably the titers of antioxidants (glutathione, ascorbic acid, proline, glycine betaine and total phenol) and activities of antioxidant enzymes (guaicol peroxidase, catalase, superoxide dismutase and glutathione reductase) in Cr-stressed plants than their individual applications. Attenuation of Cr-stress by EBL and/or Spd (more efficient with EBL and Spd combination) was also supported by enhanced values of stress indices, such as phytochelatins, photosynthetic pigments and total soluble sugars, and reduction in malondialdehyde and H2O2 levels in Cr-treated seedlings. Diminution of ROS production and enhanced ROS scavenging capacities were also noted for EBL and/or Spd under Cr-stress. However, no significant reduction in Cr uptake was observed for co-application of EBL and Spd when compared to their individual treatments in Cr-stressed seedlings. Taken together, our results demonstrate that co-applications of EBL and Spd are more effective than their independent treatments in lowering the Cr-induced oxidative stress in radish, leading to improved growth of radish seedlings under Cr-stress

Actin: its cumbersome pilgrimage through cellular compartments

In this article, we follow the history of one of the most abundant, most intensely studied proteins of the eukaryotic cells: actin. We report on hallmarks of its discovery, its structural and functional characterization and localization over time, and point to present days’ knowledge on its position as a member of a large family. We focus on the rather puzzling number of diverse functions as proposed for actin as a dual compartment protein. Finally, we venture on some speculations as to its origin

Oxidative stress‐triggered interactions between the succinyl‐ and acetyl‐proteomes of rice leaves

Protein lysine acylations, such as succinylation and acetylation, are important post‐translational modification (PTM) mechanisms, with key roles in cellular regulation. Antibody‐based affinity enrichment, high‐resolution liquid chromatography mass spectrometry analysis, and integrated bioinformatics analysis were used to characterize the lysine succinylome (Ksuc) and acetylome (Kace) of rice leaves. In total, 2,593 succinylated and 1,024 acetylated proteins were identified, of which 723 were simultaneously acetylated and succinylated. Proteins involved in photosynthetic carbon metabolism such as the large and small subunits of RuBisCO, ribosomal functions, and other key processes were subject to both PTMs. Preliminary insights into oxidant‐induced changes to the rice acetylome and succinylome were gained from treatments with hydrogen peroxide. Exposure to oxidative stress did not regulate global changes in the rice acetylome or succinylome but rather led to modifications on a specific subset of the identified sites. De‐succinylation of recombinant catalase (CATA) and glutathione S‐transferase (OsGSTU6) altered the activities of these enzymes showing that this PTM may have a regulatory function. These findings not only greatly extend the list of acetylated and/or succinylated proteins but they also demonstrate the close cooperation between these PTMs in leaf proteins with key metabolic functions