Developmental expression of plasma glutathione peroxidase during mouse organogenesis

Plasma glutathione peroxidase (pGPx) is an extracellular antioxidative selenoenzyme which has been detected in various adult tissues, but little is known about the expression and distribution of pGPx during embryogenesis. To investigate the expression patterns of pGPx during embryogenesis, we performed quantitative real-time PCR, in situ hybridization, Western blot, and immunohistochemistry analyses in whole embryos or each developing organ of mice on embryonic days (E)7.5–18.5. In whole embryos of E7.5–8.5, pGPx mRNA was more typically expressed in extra-embryonic tissues including ectoplacental cone, trophectoderm, and decidual cells than in embryos. However, after E9.5, pGPx mRNA and protein levels were increased in the embryos with differentiation and growth, but trended to gradually decrease in the extra-embryonic tissues until E18.5. In sectioned embryonic tissues on E13.5–18.5, pGPx mRNA and protein were mainly expressed in the developing nervous tissues, the sensory organs, and the epithelia of lung, skin, and intestine, the heart and artery, and the kidney. In particular, pGPx immunoreactivity was very strong in the developing liver. These results indicate that pGPx is spatio-temporally expressed in various embryonic organs as well as extra-embryonic tissues, suggesting that pGPx may function to protect the embryos against endogenous and exogenous reactive oxygen species during organogenesis.     

Effect of CCS on the accumulation of FALS SOD1 mutant-containing aggregates and on mitochondrial translocation of SOD1 mutants: implication of a free radical hypothesis

Missense mutations of SOD1 are linked to familial amyotrophic lateral sclerosis (FALS) through a yet-to-be identified toxic-gain-of-function. One of the proposed mechanisms involves enhanced aggregate formation. However, a recent study showed that dual transgenic mice overexpressing both G93A and CCS copper chaperone (G93A/CCS) exhibit no SOD1-positive aggregates yet show accelerated FALS symptoms with enhanced mitochondrial pathology compared to G93A mice. Using a dicistronic mRNA to simultaneously generate hSOD1 mutants, G93A, A4V and G85R, and hCCS in AAV293 cells, we revealed: (i) CCS is degraded primarily via a macroautophagy pathway. It forms a stable heterodimer with inactive G85R, and via its novel copper chaperone-independent molecular chaperone activity facilitates G85R degradation via a macroautophagy-mediated pathway. For active G93A and A4V, CCS catalyzes their maturation to form active and soluble homodimers. (ii) CCS reduces, under non-oxidative conditions, yet facilitates in the presence of H₂O₂, mitochondrial translocation of inactive SOD1 mutants. These results, together with previous reports showing FALS SOD1 mutants enhanced free radical-generating activity, provide a mechanistic explanation for the observations with G93A/CCS dual transgenic mice and suggest that free radical generation by FALS SOD1, enhanced by CCS, may, in part, be responsible for the FALS SOD1 mutant-linked aggregation, mitochondrial translocation, and degradation.     

MiR-3120 is a mirror microRNA that targets heat shock cognate protein 70 and auxilin messenger RNAs and regulates clathrin vesicle uncoating

We show that a single gene locus gives rise to two fully processed and functional miRNAs, i.e. that due to imperfect base pairing, two distinct microRNAs (miRNAs) can be produced from the fully complementary DNA strands. The antisense strand encodes miR-214, which is transcribed by its own promoter, whereas a novel miRNA, miR-3120, is co-expressed with its host gene mRNA. We also found that miR-3120 regulates important aspects of cellular function that are similar to that of its host gene, dynamin-3. miR-3120 was found to be located in neuronal cell bodies and to target Hsc70 and auxilin, and its lentivirus-mediated expression inhibited the uncoating of clathrin-coated vesicles. Finally, mirror miRNAs are likely to represent a new group of miRNAs with complex roles in coordinating gene expression.     

The statistics of urban scaling and their connection to Zipf's law

Urban scaling relations characterizing how diverse properties of cities vary on average with their population size have recently been shown to be a general quantitative property of many urban systems around the world. However, in previous studies the statistics of urban indicators were not analyzed in detail, raising important questions about the full characterization of urban properties and how scaling relations may emerge in these larger contexts. Here, we build a self-consistent statistical framework that characterizes the joint probability distributions of urban indicators and city population sizes across an urban system. To develop this framework empirically we use one of the most granular and stochastic urban indicators available, specifically measuring homicides in cities of Brazil, Colombia and Mexico, three nations with high and fast changing rates of violent crime. We use these data to derive the conditional probability of the number of homicides per year given the population size of a city. To do this we use Bayes' rule together with the estimated conditional probability of city size given their number of homicides and the distribution of total homicides. We then show that scaling laws emerge as expectation values of these conditional statistics. Knowledge of these distributions implies, in turn, a relationship between scaling and population size distribution exponents that can be used to predict Zipf's exponent from urban indicator statistics. Our results also suggest how a general statistical theory of urban indicators may be constructed from the stochastic dynamics of social interaction processes in cities.     

Mesenchymal stem cells restore CCl4‐induced liver injury by an antioxidative process

We have investigated BM (bone marrow)‐derived MSCs (mesenchymal stem cells) for the treatment of liver injury. It was hypothesized that MSC‐mediated resolution of liver injury could occur through an antioxidative process. After being injected with CCl₄ (carbon tetrachloride), mice were injected with syngenic BM‐derived MSCs or normal saline. Oxidative stress activity of the MSCs was determined by the analysis of ROS (reactive oxygen species) and SOD (superoxide dismutase) activity. In addition, cytoprotective genes of the liver tissue were assessed by real‐time PCR and ARE (antioxidant‐response element) reporter assay. Up‐regulated ROS of CCl₄‐treated liver cells was attenuated by co‐culturing with MSCs. Suppression of SOD by adding an SOD inhibitor decreased the effect of MSCs on injured liver cells. MSCs significantly increased SOD activity and inhibited ROS production in the injured liver. The gene expression levels of Hmox‐1 (haem oxygenase‐1), BI‐1 (Bax inhibitor‐1), HGF (hepatocyte growth factor), GST (glutathione transferase) and Nrf2 (nuclear factor‐erythoid 2 p45 subunit‐related factor 20), attenuated by CCl₄, were increased up to basal levels after MSC transplantation. In addition, MSCs induced an ARE, shown by luciferase activity, which represented a cytoprotective response in the injured liver. Evidence of a new cytoprotective effect is shown in which MSCs promote an antioxidant response and supports the potential of using MSC transplantation as an effective treatment modality for liver disease.     

Dimethyl sulfoxide and ethanol elicit increased amyloid biogenesis and amyloid-integrated biofilm formation in Escherichia coli

Escherichia coli directs the assembly of functional amyloid fibers termed "curli" that mediate adhesion and biofilm formation. We discovered that E. coli exhibits a tunable and selective increase in curli protein expression and fiber assembly in response to moderate concentrations of dimethyl sulfoxide (DMSO) and ethanol. Furthermore, the molecular alterations resulted in dramatic functional phenotypes associated with community behavior, including (i) cellular agglutination in broth, (ii) altered colony morphology, and (iii) increased biofilm formation. Solid-state nuclear magnetic resonance (NMR) spectra of intact pellicles formed in the presence of [(13)C(2)]DMSO confirmed that DMSO was not being transformed and utilized directly for metabolism. Collectively, the chemically induced phenotypes emphasize the plasticity of E. coli's response to environmental stimuli to enhance amyloid production and amyloid-integrated biofilm formation. The data also support our developing model of the extracellular matrix as an organized assembly of polymeric components, including amyloid fibers, in which composition relates to bacterial physiology and community function.     

Pulmonary administered palmitic-acid modified exendin-4 peptide prolongs hypoglycemia in type 2 diabetic db/db mice

Hypoglycemia caused by palmitic-acid modified exendin-4 (Pal-Ex4) administered via the pulmonary route was evaluated and compared with that caused by native Ex4. Pal-Ex4 and Ex4 in solution (each 50 μl) were administered using a microsprayer directly into the trachea of type 2 diabetic db/db mice at 75 or 150 nmol/kg. The lung depositions of Cy5.5-labeled Ex4 or Pal-Ex4 were monitored using an infrared imaging system after administration. The hypoglycemia caused by Pal-Ex4 was found to be 3.4 and 2.3 times greater than that caused by native Ex4 at 75 and 150 nmol/kg, respectively. Furthermore, time to blood glucose level (BGL) rebound to >150 mg/dl for Pal-Ex4 was 3.5 times greater than that of Ex4 (18.1 h vs. 5.2 h at 150 nmol/kg). In particular, the time taken for Pal-Ex4 to reach a BGL nadir was significantly greater than that of Ex4 (~8 h versus 4 h). Furthermore, lung deposition images clearly showed that Pal-Ex4 was slowly absorbed from lungs and barely distributed into kidneys until 8 h post-administration. It is likely that the prolonged hypoglycemia exhibited by Pal-Ex4 was due to; (i) delayed absorption in the lungs and (ii) albumin-binding in the circulation. The study demonstrates that palmitic acid-modified exendin-4 should be viewed as a long-acting inhalation candidate for the treatment of type 2 diabetes.