Mitochondrial nitric oxide in the signaling of cell integrated responses

Mitochondria are the specialized organelles for energy metabolism, but, as a typical example of system biology, they also activate a multiplicity of pathways that modulate cell proliferation and mitochondrial biogenesis or oppositely promote cell arrest and programmed cell death by a limited number of oxidative or nitrosative reactions. These reactions are influenced by matrix nitric oxide (NO) steady-state concentration, either from local production or by gas diffusion to mitochondria from the canonical sources. Likewise, in a range of ∼30-200 nM, NO turns mitochondrial O2 utilization down by binding to cytochrome oxidase and elicits a burst of superoxide anion and hydrogen peroxide that diffuses outside mitochondria. Depending on NO levels and antioxidant defenses, more or less H2O2 accumulates in cytosol and nucleus, and the resulting redox grading contributes to dual activation of proliferating and proapoptotic cascades, like ERK1/2 or p38 MAPK. Moreover, these sequential activating pathways participate in rat liver and brain development and in thyroid modulation of mitochondrial metabolism and contribute to hypothyroid phenotype through complex I nitration. On the contrary, lack of NO disrupts pathways like S-nitrosylation or H 2O2 production and likewise is a gateway to disease in amyotrophic lateral sclerosis with superoxide dismutase 1 mutations or to cancer proliferation.Fil: Carreras, Maria Cecilia. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; ArgentinaFil: Poderoso, Juan José. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; Argentin

Intercellular mitochondrial transfer through nanotubules is promoted by cyclic amp (cAMP) in rat astrocytes and human glioblastoma cells

Nanotubules (Tunneling nanotubules, TnTs) are cell membrane projectionsmade of F-actin fibers of nanometric diameter (up to 1 μm),which enable cytoplasmatic connections between cells. It has beenshown that mitochondria, other organelles, and cellular componentsare transferred by TnTs in several normal and tumor cell lines. TnTsestablishment has been extensively described in nervous systemcells, as neurons and astrocytes. Published evidence indicates theexistence of mitochondrial transfer through TnTs between differentcell types, such as normal and tumoral cells. Mitochondrial passagefrom normal to tumor cells restores oxidative metabolism, decreasingtumorigenic potential. A similar effect has been observed withcAMP, a very well-known astrocytes stellation promoter, which mediatesmitochondrial biogenesis and tumor growth inhibition. Mitochondrialtransfer within TnTs in nervous system cells have not beendemonstrated so far. Then, our goal was to analyze mitochondrialtrafficking through TnTs in normal and tumoral astrocytes and apossible effect of cAMP. We used normal rat astrocytes and humanglioblastoma U87 cells. Mitochondria and actin were probed with amito-targeted green fluorescent protein and phalloidin, respectively.Astrocytes and U87 were incubated with or without 8Br-cAMP(cAMP analogue). We analyzed images by confocal microscopy andmeasured the width of actin connections between cells. We analyzedeach culture separately; astrocytes and U87 establish thick projectionscontaining mitochondria but treatment with cAMP promotes anincrease of TnTs-like connections with mitochondria inside (controlvs cAMP: astrocytes: 2.07±0.71 vs 0.85±0.21 μm, ***p<0.05; U87:2.69±1.40 vs.0.84±0.22 μm, *p<0.05, ± SD, ANOVA, Tukey test).Thus, cAMP promotes TnTs-like structures and mitochondrial passagethrough them in normal astrocytes and glioblastoma cells, suggestinga role for intercellular mitochondrial transfer through TnTs instellation process.Fil: Helfenberger, Katia Estefanía. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Benzo, Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Duarte, Alejandra Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Fuentes, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Poderoso, Juan José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; ArgentinaFil: Maloberti, Paula Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Poderoso, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaLXV Reunión Anual de la Sociedad Argentina de Investigación Clínica; LXVIII Reunión Anual de la Sociedad Argentina de Inmunología y Reunión Anual de la Sociedad Argentina FisiologíaArgentinaSociedad Argentina de Investigación ClínicaSociedad Argentina FisiologíaSociedad Argentina de Inmunologí

Subcellular distribution of ERK phosphorylation in tyrosine and threonine depends on redox status in murine lung cells

Activation of ERK1/2 implies the phosphorylation of tyrosine (pTyr) and threonine (pThr) by MEK1/2; both reactions were thought to be cytoplasmic, promoting ERK to reach the nucleus where it activates several transcription factors. In addition, H 2 O 2 concentrations are known to modulate ERK intracellular translocation, which impacts on cellular proliferation. In this context, the objective of this work was to study the sequence of ERK phosphorylation under two redox conditions and to analyze a putative mitochondrial contribution to this process, in LP07 murine lung cells. A time-course of H 2 O 2 administration was used and ERK phosphorylation was analyzed in cytosol, mitochondria and nuclei. At 1μM H 2 O 2 , a proliferative redox stimulus, immunoblot revealed a fast and transient increase in cytosol pTyr and a sustained increase in mitochondrial pTyr content. The detection for pThr/pTyrERK (2pERK) showed in cytosol a marked increase at 5 minutes with a fast dephosphorylation after that time, for both H 2 O 2 concentrations. However, at 50 μM H 2 O 2 , an anti-proliferative condition, 2pERK was gradually retained in mitochondria. Interestingly, these results were confirmed by in vivo experiments using mice treated with a highly oxidizing agent [H 2 O 2 ]. By the use of two ERK2 mutant constructions, where Tyr and Thr were replaced by alanine, we confirmed that 2pERK relied almost completely on pThr183. Confocal microscopy confirmed ERK subcellular distribution dependence on the incidence of cytosolic pTyr and mitochondrial pThr at 1μM H 2 O 2 . This work shows for the first time, both in vitro and in vivo, an ERK cycle involving a cross-talk between cytosol and mitochondria phosphorylation events, which may play a significant role in cell cycle progression, proliferation or differentiation under two different redox conditions.Fil: Helfenberger, Katia Estefanía. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Villalba, Nerina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Buchholz, Bruno. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Boveris, Alberto Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Poderoso, Juan José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Gelpi, Ricardo Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Poderoso, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; Argentin

Inhibition of mitochondrial fission by Drp-1 blockade by short-term leptin and Mdivi-1 treatment improves white adipose tissue abnormalities in obesity and diabetes

Background: Obesity and type 2 diabetes are chronic diseases characterized by insulin resistance, mitochondrial dysfunction and morphological abnormalities. Objective: We have investigated if dysregulation of mitochondrial dynamics and biogenesis is involved in an animal model of obesity and diabetes. Methods: The effect of short-term leptin and mdivi-1 – a selective inhibitor of Drp-1 fission-protein – treatment on mitochondrial dynamics and biogenesis was evaluated in epididymal white adipose tissue (WAT) from male ob/ob mice. Results: An increase in Drp-1 protein levels and a decrease in Mfn2 and OPA-1 protein expression were observed with enhanced and sustained mitochondrial fragmentation in ob/ob mice compared to wt C57BL/6 animals (p < 0.05). The content of mitochondrial DNA and PGC-1α mRNA expression –both parameters of mitochondrial biogenesis– were reduced in ob/ob mice (p < 0.05). Treatment with leptin and mdivi-1 significantly increased mitochondrial biogenesis, improved fusion-to-fission balance and attenuated mitochondrial dysfunction, thus inducing white-to-beige adipocyte transdifferentiation. Measurements of glucose and lipid oxidation in adipocytes revealed that both leptin and mdivi-1 increase substrates oxidation while in vivo determination of blood glucose concentration showed decreased levels by 50% in ob/ob mice, almost to the wt level. Conclusions: Pharmacological targeting of Drp-1 fission protein may be a potential novel therapeutic tool for obesity and type 2 diabetes.Fil: Finocchietto, Paola Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; ArgentinaFil: Perez, Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; ArgentinaFil: Blanco, Guillermo Armando C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; ArgentinaFil: Miksztowicz, Verónica Julieta. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Fisiopatología y Bioquímica Clínica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Marotte, Clarisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; ArgentinaFil: Morales, C.. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Patología; ArgentinaFil: Peralta, Jorge Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; ArgentinaFil: Berg, G.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Instituto de Fisiopatologia y Bioquimica Clinica.; ArgentinaFil: Poderoso, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Poderoso, Juan José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; ArgentinaFil: Carreras, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; Argentin

Reactions of peroxynitrite in the mitochondrial matrix

Superoxide radical (O2 -) and nitric oxide (NO) produced at the mitochondrial inner membrane react to form peroxynitrite (ONOO-) in the mitochondrial matrix. Intramitochondrial ONOO- effectively reacts with a few biomolecules according to reaction constants and intramitochondrial concentrations. The second-order reaction constants (in M-1 s-1) of ONOO- with NADH (233 ± 27), ubiquinol-0 (485 ± 54) and GSH (183 ± 12) were determined fluorometrically by a simple competition assay of product formation. The oxidation of the components of the mitochondrial matrix by ONOO- was also followed in the presence of CO2, to assess the reactivity of the nitrosoperoxocarboxylate adduct (ONOOCO2 -) towards the same reductants. The ratio of product formation was about similar both in the presence of 2.5 mM CO2 and in air-equilibrated conditions. Liver submitochondrial particles supplemented with 0.25-2 μM ONOO- showed a O2 - production that indicated ubisemiquinone formation and autooxidation. The nitration of mitochondrial proteins produced after addition of 200 μM ONOO- was observed by Western blot analysis. Protein nitration was prevented by the addition of 50-200 μM ubiquinol-0 or GSH. An intramitochondrial steady state concentration of about 2 nM ONOO- was calculated, taking into account the rate constants and concentrations of ONOO- coreactants. (C) 2000 Elsevier Science Inc.Fil: Valdez, Laura Batriz. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Analítica y Fisicoquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Alvarez, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Bioquímica y Medicina Molecular; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Analítica y Fisicoquímica; ArgentinaFil: Lores Arnaiz, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Bioquímica y Medicina Molecular; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Analítica y Fisicoquímica; ArgentinaFil: Schöpfer, Francisco. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; ArgentinaFil: Carreras, Maria Cecilia. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Poderoso, Juan José. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Boveris, Alberto Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Analítica y Fisicoquímica; Argentin

Overexpression of neutrophil neuronal nitric oxide synthase in Parkinson's disease

Much evidence supports a role of nitric oxide (·NO) and peroxynitrite (ONOO-) in experimental and idiopathic Parkinson's disease (PD); moreover, an overexpression of neuronal nitric oxide synthase (nNOS) was recently reported in the basal ganglia of PD patients. In accord, we previously found a 50% increased ·NO production rate during the respiratory burst of circulating neutrophils (PMN) from PD patients. As PMN express the nNOS isoform, the objective of the present study was to ascertain whether this increased ·NO production is representative of nNOS gene upregulation. PMN were isolated from blood samples obtained from seven PD patients and seven age- and sex-matched healthy donors; nNOS mRNA was amplified by reverse transcriptase-polymerase chain reaction and the products were hybridized with a probe for nNOS. Nitrotyrosine-containing proteins and nNOS were detected by Western blot and NO production rate was measured spectrophotometrically by the conversion of oxymyoglobin to metmyoglobin. The results showed that both ·NO production and protein tyrosine nitration were significantly increased in PMN isolated from PD patients (PD 0.09 ± 0.01 vs 0.06 ± 0.008 nmol min-1 106 cells-1; P < 0.05). In addition, five of the seven PD patients showed about 10-fold nNOS mRNA overexpression; while two of the seven PD patients showed an expression level similar to that of the controls; detection of nNOS protein was more evident in the former group. In summary, it is likely that overexpression of nNOS and formation of ONOO- in PMN cells from PD patients emphasizes a potential causal role of ·NO in the physiopathology of the illness. (C) 2000 Academic Press.Fil: Gatto, Emilia Mabel. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; ArgentinaFil: Riobó, Natalia A.. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; ArgentinaFil: Carreras, Maria Cecilia. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cherñavsky, Alejandra Claudia. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Inmunogenética; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; ArgentinaFil: Rubio, Andrea. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Inmunogenética; ArgentinaFil: Satz, M. Leonardo. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Inmunogenética; ArgentinaFil: Poderoso, Juan José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; Argentin

Progesterone protective effects in neurodegeneration and neuroinflamation

Progesterone is a neuroprotective, promyelinating and antiinflammatory  factor for the nervous system. Here we discuss progesterone effects in models of  motoneuron degeneration and neuroinflammation. In neurodegeneration of the  Wobbler mouse, a subset of spinal cord motoneurons showed increased activity of  nitric oxide synthase (NOS), increased intramitochondrial NOS, decreased activity of  respiratory chain complexes and decreased activity and protein expression of Mnsuperoxide  dismutase type 2 (MnSOD2). Clinically, Wobblers suffered several  degrees of motor impairment. Progesterone treatment restored the expression of  neuronal markers, decreased the activity of NOS and enhanced complex I  respiratory activity and MnSOD2. Long-term treatment with progesterone increased  muscle strength, biceps weight and survival. Collectively, these data supported that  progesterone prevented neurodegeneration. To study progesterone effects in  neuroinflammation, we employed mice with experimental autoimmune  encephalomyelitis (EAE). EAE mice spinal cord showed increased mRNA levels of  the inflammatory mediators tumour necrosis factor α (TNFα) and its receptor TNFR1,  the microglial marker CD11b, iNOS and the toll-like receptor 4 (TLR4). Progesterone  pretreatment of EAE mice blocked the proinflammatory mediators, decreased Iba1+  microglial cells and attenuated clinical signs of EAE. Therefore, reactive glial cells  became targets of progesterone anti-inflammatory effects. These results open the  ground for testing the usefulness of neuroactive steroids for neurological disorders.Fil: de Nicola, Alejandro Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Gonzalez Deniselle, Maria Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Garay, Laura Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Meyer, Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Gargiulo Monachelli, Gisella Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Guennoun, Rachida. Inserm; Francia. Universite Paris Sud; FranciaFil: Schumacher, M.. Inserm; Francia. Universite Paris Sud; FranciaFil: Carreras, Maria Cecilia. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo; ArgentinaFil: Poderoso, Juan José. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo; Argentin

The Pan-Caspase Inhibitor Emricasan (IDN-6556) decreases liver injury and fibrosis in a murine model of non-alcoholic steatohepatitis

BACKGROUND & AIMS: Hepatocyte apoptosis, the hallmark of non-alcoholic steatohepatitis (NASH) contributes to liver injury and fibrosis. Although, both the intrinsic and extrinsic apoptotic pathways are involved in the pathogenesis of NASH, the final common step of apoptosis is executed by a family of cysteine-proteases termed caspases. Thus, our aim was to ascertain if administration of Emricasan, a pan-caspase inhibitor, ameliorates liver injury and fibrosis in a murine model of NASH. METHODS: C57/BL6J-mice were fed regular chow or high fat diet (HFD) for 20 weeks. All mice were treated with vehicle or Emricasan. RESULTS: Mice fed a HFD diet demonstrate a five-fold increase in hepatocyte apoptosis by the TUNEL assay and a 1.5-fold and 1.3-fold increase in caspase-3 and-8 activities respectively; this increase in apoptosis was substantially attenuated in mice fed a HFD treated with Emricasan (HFD-Em). Likewise, liver injury and inflammation were reduced in mice fed HFD-Em as compare to HFD by measuring serum aspartate aminotransferase and alanine aminotransferase levels, NAS histological score and IL 1-β, TNF-α, monocyte chemoattractant protein (MCP-1) and C-X-C chemokine ligand-2 (CXCL2) quantitative reverse-transcription polymerase chain reaction (qPCR). These differences could not be attributed to differences in hepatic steatosis as liver triglycerides content were similar in both HFD groups. Hepatic fibrosis was reduced by Emricasan in HFD animals by decreasing αSMA (a marker for hepatic stellate cell activation), fibrosis score, Sirius red staining, hydroxyproline liver content and profibrogenic cytokines by qPCR. CONCLUSION: In conclusion, these data demonstrate that in a murine model of NASH, liver injury and fibrosis are suppressed by inhibiting hepatocytes apoptosis and suggests that Emricasan may be an attractive antifibrotic therapy in NASH.Fil: Barreyro, Fernando Javier. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Departamento de Microbiología; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Holod, Silvia. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; ArgentinaFil: Finocchietto, Paola Vanesa. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; ArgentinaFil: Camino, Alejandra M.. DIM Clínica Privada; ArgentinaFil: Aquino, Jorge Benjamin. Universidad Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Avagnina, Alejandra. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Carreras, Maria Cecilia. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Poderoso, Juan José. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Metabolismo del Oxígeno; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gores, Gregory J.. Mayo Clinic College of Medicine; Estados Unido

New Algorithm to Determine True Colocalization in Combination with Image Restoration and Time-Lapse Confocal Microscopy to Map Kinases in Mitochondria

The subcellular localization and physiological functions of biomolecules are closely related and thus it is crucial to precisely determine the distribution of different molecules inside the intracellular structures. This is frequently accomplished by fluorescence microscopy with well-characterized markers and posterior evaluation of the signal colocalization. Rigorous study of colocalization requires statistical analysis of the data, albeit yet no single technique has been established as a standard method. Indeed, the few methods currently available are only accurate in images with particular characteristics. Here, we introduce a new algorithm to automatically obtain the true colocalization between images that is suitable for a wide variety of biological situations. To proceed, the algorithm contemplates the individual contribution of each pixel's fluorescence intensity in a pair of images to the overall Pearsońs correlation and Manders' overlap coefficients. The accuracy and reliability of the algorithm was validated on both simulated and real images that reflected the characteristics of a range of biological samples. We used this algorithm in combination with image restoration by deconvolution and time-lapse confocal microscopy to address the localization of MEK1 in the mitochondria of different cell lines. Appraising the previously described behavior of Akt1 corroborated the reliability of the combined use of these techniques. Together, the present work provides a novel statistical approach to accurately and reliably determine the colocalization in a variety of biological images

Tumor Cell Phenotype Is Sustained by Selective MAPK Oxidation in Mitochondria

Mitochondria are major cellular sources of hydrogen peroxide (H2O2), the production of which is modulated by oxygen availability and the mitochondrial energy state. An increase of steady-state cell H2O2 concentration is able to control the transition from proliferating to quiescent phenotypes and to signal the end of proliferation; in tumor cells thereby, low H2O2 due to defective mitochondrial metabolism can contribute to sustain proliferation. Mitogen-activated protein kinases (MAPKs) orchestrate signal transduction and recent data indicate that are present in mitochondria and regulated by the redox state. On these bases, we investigated the mechanistic connection of tumor mitochondrial dysfunction, H2O2 yield, and activation of MAPKs in LP07 murine tumor cells with confocal microscopy, in vivo imaging and directed mutagenesis. Two redox conditions were examined: low 1 µM H2O2 increased cell proliferation in ERK1/2-dependent manner whereas high 50 µM H2O2 arrested cell cycle by p38 and JNK1/2 activation. Regarding the experimental conditions as a three-compartment model (mitochondria, cytosol, and nuclei), the different responses depended on MAPKs preferential traffic to mitochondria, where a selective activation of either ERK1/2 or p38-JNK1/2 by co-localized upstream kinases (MAPKKs) facilitated their further passage to nuclei. As assessed by mass spectra, MAPKs activation and efficient binding to cognate MAPKKs resulted from oxidation of conserved ERK1/2 or p38-JNK1/2 cysteine domains to sulfinic and sulfonic acids at a definite H2O2 level. Like this, high H2O2 or directed mutation of redox-sensitive ERK2 Cys214 impeded binding to MEK1/2, caused ERK2 retention in mitochondria and restricted shuttle to nuclei. It is surmised that selective cysteine oxidations adjust the electrostatic forces that participate in a particular MAPK-MAPKK interaction. Considering that tumor mitochondria are dysfunctional, their inability to increase H2O2 yield should disrupt synchronized MAPK oxidations and the regulation of cell cycle leading cells to remain in a proliferating phenotype