Analysis of nearly planar defects using the Thomas--Fermi--von Weiszacker model

We analyze the convergence of the electron density and relative energy with respect to a perfect crystal of a class of volume defects that are compactly contained along one direction while being of infinite extent along the other two using the Thomas-Fermi-von Weiszacker (TFW) model. We take advantage of prior work on the thermodynamic limit and stability estimates in the TFW setting, and specialize it to the case of nearly planar defects. In particular, we prove that the relative energy of the defective crystal, with respect to a perfect crystal, is finite, and in fact conforms to a well-posed minimization problem. We also establish convergence of the electronic fields to the perturbation caused by the nearly planar defect. Our main finding is that perturbations to both the density and electrostatic potential due to the presence of the nearly planar defect decay exponentially away from the defect, in agreement with the known locality property of the TFW model. We use these results to infer bounds on the generalized stacking fault energy, in particular the finiteness of this energy, and discuss its implications for numerical calculations. We conclude with a brief presentation of numerical results on the (non-convex) Thomas-Fermi-von Weiszacker-Dirac (TFWD) model that includes the Dirac exchange in the universal functional, and discuss its implications for future work.Comment: 40 pages, 10 figure

Kadukkai maathirai (a polyherbal traditional siddha formulation) prevents D-galactosamine induced hepatic necrosis in rats

708-713This study evaluated the prophylactic effect of Kadukkai maathirai in D-galactosamine (D-gal) induced hepatotoxicity in rats. D-galactosamine (D-gal) 400 mg/kg intraperitoneally was used to induce liver damage in rats. To assess the hepatoprotective effect of KM, three different doses of KM (36, 72 and 144 mg/kg body weight) were used. The hepatoprotective effect of KM was compared with standard drug silymarin (50 mg/kg). The biochemical parameters such as AST, ALT, ALP and total bilirubin were estimated. The livers were dissected out to look for histological changes. KM 144 mg/kg and silymarin showed a significant decrease in AST, ALP and total bilirubin. Both KM and silymarin significantly prevented decrease in liver weight. In KM treated groups, the liver did not show necrosis of hepatocytes, and apoptotic bodies with mild to moderate inflammatory infiltrate in the lobules and portal tracts. Hence, the results of this study confirms the hepatoprotective effect KM in rats

Kadukkai maathirai (a polyherbal traditional siddha formulation) prevents D-galactosamine induced hepatic necrosis in rats

This study evaluated the prophylactic effect of Kadukkai maathirai in D-galactosamine (D-gal) induced hepatotoxicity in rats. D-galactosamine (D-gal) 400 mg/kg intraperitoneally was used to induce liver damage in rats. To assess the hepatoprotective effect of KM, three different doses of KM (36, 72 and 144 mg/kg body weight) were used. The hepatoprotective effect of KM was compared with standard drug silymarin (50 mg/kg). The biochemical parameters such as AST, ALT, ALP and total bilirubin were estimated. The livers were dissected out to look for histological changes. KM 144 mg/kg and silymarin showed a significant decrease in AST, ALP and total bilirubin. Both KM and silymarin significantly prevented decrease in liver weight. In KM treated groups, the liver did not show necrosis of hepatocytes, and apoptotic bodies with mild to moderate inflammatory infiltrate in the lobules and portal tracts. Hence, the results of this study confirms the hepatoprotective effect KM in rats

The Chop Gene Contains an Element for the Positive Regulation of the Mitochondrial Unfolded Protein Response

We have previously reported on the discovery of a mitochondrial specific unfolded protein response (mtUPR) in mammalian cells, in which the accumulation of unfolded protein within the mitochondrial matrix results in the transcriptional activation of nuclear genes encoding mitochondrial stress proteins such as chaperonin 60, chaperonin 10, mtDnaJ, and ClpP, but not those encoding stress proteins of the endoplasmic reticulum (ER) or the cytosol. Analysis of the chaperonin 60/10 bidirectional promoter showed that the CHOP element was required for the mtUPR and that the transcription of the chop gene is activated by mtUPR. In order to investigate the role of CHOP in the mtUPR, we carried out a deletion analysis of the chop promoter. This revealed that the transcriptional activation of the chop gene by mtUPR is through an AP-1 (activator protein-1) element. This site lies alongside an ERSE element through which chop transcription is activated in response to the ER stress response (erUPR). Thus CHOP can be induced separately in response to 2 different stress response pathways. We also discuss the potential signal pathway between mitochondria and the nucleus for the mtUPR

Activation of Akt Is Essential for the Propagation of Mitochondrial Respiratory Stress Signaling and Activation of the Transcriptional Coactivator Heterogeneous Ribonucleoprotein A2

This article shows that mitochondrial respiratory dysfunction activates a stress signaling that induces Akt1 activation. Akt1 activation occurs through calcineurin-mediated IGF1R/PI3-K pathway. Akt1-mediated phosphorylation of hnRNPA2 is a key requirement for the propagation of stress signaling and activation of nuclear target genes

CD133 Is a Marker of Bioenergetic Stress in Human Glioma

Mitochondria dysfunction and hypoxic microenvironment are hallmarks of cancer cell biology. Recently, many studies have focused on isolation of brain cancer stem cells using CD133 expression. In this study, we investigated whether CD133 expression is regulated by bioenergetic stresses affecting mitochondrial functions in human glioma cells. First, we determined that hypoxia induced a reversible up-regulation of CD133 expression. Second, mitochondrial dysfunction through pharmacological inhibition of the Electron Transport Chain (ETC) produced an up-regulation of CD133 expression that was inversely correlated with changes in mitochondrial membrane potential. Third, generation of stable glioma cells depleted of mitochondrial DNA showed significant and stable increases in CD133 expression. These glioma cells, termed rho0 or ρ0, are characterized by an exaggerated, uncoupled glycolytic phenotype and by constitutive and stable up-regulation of CD133 through many cell passages. Moreover, these ρ0 cells display the ability to form “tumor spheroids” in serumless medium and are positive for CD133 and the neural progenitor cell marker, nestin. Under differentiating conditions, ρ0 cells expressed multi-lineage properties. Reversibility of CD133 expression was demonstrated by transfering parental mitochondria to ρ0 cells resulting in stable trans-mitochondrial “cybrid” clones. This study provides a novel mechanistic insight about the regulation of CD133 by environmental conditions (hypoxia) and mitochondrial dysfunction (genetic and chemical). Considering these new findings, the concept that CD133 is a marker of brain tumor stem cells may need to be revised

Pre-microRNA and Mature microRNA in Human Mitochondria

Chantier qualité GAInternational audienceBACKGROUND: Because of the central functions of the mitochondria in providing metabolic energy and initiating apoptosis on one hand and the role that microRNA (miRNA) play in gene expression, we hypothesized that some miRNA could be present in the mitochondria for post-transcriptomic regulation by RNA interference. We intend to identify miRNA localized in the mitochondria isolated from human skeletal primary muscular cells. METHODOLOGY/PRINCIPAL FINDINGS: To investigate the potential origin of mitochondrial miRNA, we in-silico searched for microRNA candidates in the mtDNA. Twenty five human pre-miRNA and 33 miRNA aligments (E-value35) for the smallest RNA input concentration and 204 miRNA for the maximum RNA input concentration. In silico analysis predicted 80 putative miRNA target sites in the mitochondrial genome (E-value<0.05). CONCLUSIONS/SIGNIFICANCE: The present study experimentally demonstrated for the first time the presence of pre-miRNA and miRNA in the human mitochondria isolated from skeletal muscular cells. A set of miRNA were significantly detected in mitochondria fraction. The origin of these pre-miRNA and miRNA should be further investigate to determine if they are imported from the cytosol and/or if they are partially processed in the mitochondria

A Novel Intracellular Isoform of Matrix Metalloproteinase-2 Induced by Oxidative Stress Activates Innate Immunity

Experimental and clinical evidence has pinpointed a critical role for matrix metalloproteinase-2 (MMP-2) in ischemic ventricular remodeling and systolic heart failure. Prior studies have demonstrated that transgenic expression of the full-length, 68 kDa, secreted form of MMP-2 induces severe systolic failure. These mice also had unexpected and severe mitochondrial structural abnormalities and dysfunction. We hypothesized that an additional intracellular isoform of MMP-2, which affects mitochondrial function is induced under conditions of systolic failure-associated oxidative stress.Western blots of cardiac mitochondria from the full length MMP-2 transgenics, ageing mice and a model of accelerated atherogenesis revealed a smaller 65 kDa MMP-2 isoform. Cultured cardiomyoblasts subjected to transient oxidative stress generated the 65 kDa MMP-2 isoform. The 65 kDa MMP-2 isoform was also induced by hypoxic culture of cardiomyoblasts. Genomic database analysis of the MMP-2 gene mapped transcriptional start sites and RNA transcripts induced by hypoxia or epigenetic modifiers within the first intron of the MMP-2 gene. Translation of these transcripts yields a 65 kDa N-terminal truncated isoform beginning at M(77), thereby deleting the signal sequence and inhibitory prodomain. Cellular trafficking studies demonstrated that the 65 kDa MMP-2 isoform is not secreted and is present in cytosolic and mitochondrial fractions, while the full length 68 kDa isoform was found only in the extracellular space. Expression of the 65 kDa MMP-2 isoform induced mitochondrial-nuclear stress signaling with activation of the pro-inflammatory NF-κB, NFAT and IRF transcriptional pathways. By microarray, the 65 kDa MMP-2 induces an innate immunity transcriptome, including viral stress response genes, innate immunity transcription factor IRF7, chemokines and pro-apoptosis genes.A novel N-terminal truncated intracellular isoform of MMP-2 is induced by oxidative stress. This isoform initiates a primary innate immune response that may contribute to progressive cardiac dysfunction in the setting of ischemia and systolic failure