Browsing by Author "Sobrevia, Luis "

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    A Role for Insulin on L-Arginine Transport in Fetal Endothelial Dysfunction in Hyperglycaemia
    (BENTHAM SCIENCE PUBL LTD, 2009) Sobrevia, Luis; Gonzalez, Marcelo
    Endothelial cells are key in the regulation of vascular tone through the release of vasoactive molecules, including nitric oxide (NO). NO is a gas synthesized from the cationic amino acid L-arginine via the endothelial NO synthase (eNOS). The semi-essential amino acid L-arginine is a taken up by endothelial cells via systems y(+) and y(+)L in primary cultures of human umbilical vein endothelial cells (HUVEC). System y(+) is a family of membrane transporters including at least five transport systems for cationic amino acids (CAT) of which HUVEC express human CAT-1 (hCAT-1) and hCAT-2B. Exposure of HUVEC to high extracellular concentrations of D-glucose increases L-arginine transport, hCAT-1 mRNA expression and eNOS activity. These phenomena are also related with increased production of reactive oxygen species (ROS), thus supporting the possibility that changes in L-arginine/NO signalling pathway result from elevated ROS. It has been shown that insulin blocks D-glucose-increased L-arginine transport and cGMP accumulation in HUVEC, whereas in this cell type insulin also modulates high D-glucose effects by activating the transcriptional factors Sp1 and NF kappa B. These transcription factors have response elements in SLC7A1 (for hCAT-1) gene promoter region, thus representing 2 possible targets for regulation of the expression of this transporter by D-glucose and/or insulin in this cell type. Recent evidences suggest that insulin blocks the stimulatory effect of D- glucose on L-arginine transport by reducing the transcriptional activity of SLC7A1 via Sp1-, NF kappa B- and ROS-dependent mechanisms. Thus, a role for these transcription factors in response to insulin is proposed in fetal endothelial cells exposed to hyperglycaemia.
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    Activation of Transcriptional Response Elements of Endoplasmic Reticulum Stress in Human Umbilical Vein Endothelial Cells from Maternal Obesity.
    (SAGE PUBLICATIONS INC, 2016) Pizarro, Carolina; Villalobos Labra, Roberto; Westermeier, Francisco; Saez, Pablo; Sobrevia, Luis; Farias Jofre, Marcelo
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    D-Glucose stimulation of L-arginine transport and nitric oxicle synthesis results from activation of mitogen-activated protein kinases p42/44 and smad2 requiring functional type II TGF-beta receptors in human umbilical vein endothelium
    (WILEY, 2007) Vasquez, Rodrigo; Farias, Marcelo; Vega, Jost Luis; Martin, Rody San; Vecchiola, Andrea; Casanello, Paola; Sobrevia, Luis
    Elevated extracellular D-glucose increases transforming growth factor P I (TGF-P 1) release from human umbilical vein endothelium (HUVEC). TGF-P 1, via TGF-P receptors I (T beta RI) and T beta RII, activates Smad2 and mitogen -activated protein kinases p44 and p42 (p42/44 (mapk)). We studied whether D-glucose-stimulation Of L-arginine transport and nitric oxide synthesis involves TGF-beta 1 in primary cultures of HUVEC. TGF-P I release was higher (similar to 1.6-fold) in 25 mM (high) compared with 5 mM (normal) D-glucose. TGF-P I increases L-arginine transport (half maximal effect similar to 1.6 ng/ml) in normal D-glucose, but did not alter high D-glucose-increased L-arginine transport. TGF-P I and high D-glucose increased hCAT- I mRNA expression (similar to 8-fold) and maximal transport velocity (V-max), L- [(3) H]citrulline formation from L- [3 H]arginine (index of NO synthesis) and endothelial NO synthase (eNOS) protein abundance, but did not alter eNOS phosphorylation. TGF-beta 1 I and high D-gludose increased p42/44 mapk and Smad2 phosphorylation, an effect blocked by PD-98059 (MEK 1 /2 inhibitor). However, TGF-P I and high D-glucose were ineffective in cells expressing a truncated, negative dominant T beta RII High D-glucose increases L-arginine transport and eNOS expression following T beta RII activation by TGF-P I involving p42/44 (mapk) and Smad2 in HUVEC. Thus, TGF-P I could play a crucial role under conditions of hyperglycemia, such as gestational diabetes mellitus, which is
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    Epigenetics: New Concepts of Old Phenomena in Vascular Physiology
    (BENTHAM SCIENCE PUBL LTD, 2009) Krause, Bernardo; Sobrevia, Luis; Casanello, Paola
    The hypothesis of 'Developmental Origins of Health and Disease' (DOHaD) relies on the presence of mechanisms sensing and signalling a diversity of stimuli during fetal development. The mechanisms that have been broadly suggested to be involved in these processes are the epigenetic modifications that could 'record' perinatal stimuli. Since the definition of epigenetic and the associated mechanisms are conflictive, in this review epigenetic was defined as 'chromosome-based mechanisms that can change the phenotypic plasticity in a cell or organism'. The most understood epigenetic mechanisms (i.e. DNA methylation, histone post-translational modifications (PTM), ATP-dependent chromatin modifications and non-coding RNAs) and reported evidence for their role in fetal programming were briefly reviewed.
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    Functional consequences of SARS-CoV-2 infection in pregnant women, fetoplacental unit, and neonate
    (ELSEVIER, 2023) Carvajal, Jorge; Casanello, Paola; Toso, Alberto; Farias, Marcelo; Carrasco-Negue, Karina; Araujo, Kenny; Valero, Paola; Fuenzalida, Javiera; Solari, Caterina; Sobrevia, Luis
    The SARS-CoV-2 infection causes COVID-19 disease, characterized by acute respiratory distress syndrome, bilateral pneumonia, and organ failure. The consequences of maternal SARS-CoV-2 infection for the pregnant woman, fetus, and neonate are controversial. Thus, it is required to determine whether there is viral and non -viral vertical transmission in COVID-19. The disease caused by SARS-CoV-2 leads to functional alterations in asymptomatic and symptomatic pregnant women, the fetoplacental unit and the neonate. Several diseases of pregnancy, including COVID-19, affect the fetoplacental function, which causes in utero programming for young and adult diseases. A generalized inflammatory state and a higher risk of infection are seen in pregnant women with COVID-19. Obesity, diabetes mellitus, and hypertension may increase the vulnerability of pregnant women to infection by SARS-CoV-2. Alpha, Delta, and Omicron variants of SARS-CoV-2 show specific mutations that seem to increase the capacity of the virus to infect the pregnant woman, likely due to increasing its interaction via the virus S protein and angiotensin-converting enzyme 2 receptors. This review shows the literature addressing to what extent COVID-19 in pregnancy affects the pregnant woman, fetoplacental unit, and neonate. Prospective studies that are key in managing SARS-CoV-2 infection in pregnancy are discussed.
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    Functional Link Between Adenosine and Insulin: A Hypothesis for Fetoplacental Vascular Endothelial Dysfunction in Gestational Diabetes
    (BENTHAM SCIENCE PUBL LTD, 2011) Guzman Gutierrez, Enrique; Abarzua, Fernando; Belmar, Cristian; Nien, Jyh K.; Ramirez, Marco A.; Arroyo, Pablo; Salomon, Carlos; Westermeier, Francisco; Puebla, Carlos; Leiva, Andrea; Casanello, Paola; Sobrevia, Luis
    Gestational diabetes mellitus (GDM) is a syndrome compromising the health of the mother and the fetus. Endothelial damage and reduced metabolism of the vasodilator adenosine occur and fetal hyperinsulinemia associated with deficient insulin response and a metabolic rather than mitogenic phenotype is characteristic of this pathology. These phenomena lead to endothelial dysfunction of the fetoplacental unit. Major databases were searched for the relevant literature in the field. Special attention was placed on publications related with diabetes and hormone/metabolic disorders. We aimed to summarize the information regarding insulin sensitivity changes in GDM and the role of adenosine in this phenomenon. Evidence supporting the possibility that fetal endothelial dysfunction involves a functional link between adenosine and insulin signaling in the fetal endothelium from GDM pregnancies is summarized. Since insulin acts via membrane receptors type A (preferentially associated with mitogenic responses) or type B (preferentially associated with metabolic responses), a differential activation of these receptors in this syndrome is proposed.
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    Gestational Diabetes Reduces Adenosine Transport in Human Placental Microvascular Endothelium, an Effect Reversed by Insulin
    (PUBLIC LIBRARY SCIENCE, 2012) Salomon, Carlos; Westermeier, Francisco; Puebla, Carlos; Arroyo, Pablo; Guzman Gutierrez, Enrique; Pardo, Fabian; Leiva, Andrea; Casanello, Paola; Sobrevia, Luis
    Gestational diabetes mellitus (GDM) courses with increased fetal plasma adenosine concentration and reduced adenosine transport in placental macrovascular endothelium. Since insulin modulates human equilibrative nucleoside transporters (hENTs) expression/activity, we hypothesize that GDM will alter hENT2-mediated transport in human placental microvascular endothelium (hPMEC), and that insulin will restore GDM to a normal phenotype involving insulin receptors A (IR-A) and B (IR-B). GDM effect on hENTs expression and transport activity, and IR-A/IR-B expression and associated cell signalling cascades (p42/44 mitogen-activated protein kinases (p42/44(mapk)) and Akt) role in hPMEC primary cultures was assayed. GDM associates with elevated umbilical whole and vein, but not arteries blood adenosine, and reduced hENTs adenosine transport and expression. IR-A/IR-B mRNA expression and p42/44(mapk)/Akt ratios ('metabolic phenotype') were lower in GDM. Insulin reversed GDM-reduced hENT2 expression/activity, IR-A/IR-B mRNA expression and p42/44(mapk)/Akt ratios to normal pregnancies ('mitogenic phenotype'). It is suggested that insulin effects required IR-A and IR-B expression leading to differential modulation of signalling pathways restoring GDM-metabolic to a normal-mitogenic like phenotype. Insulin could be acting as protecting factor for placental microvascular endothelial dysfunction in GDM.
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    High D-Glucose reduces SLC29A1 promoter activity and adenosine transport involving specific protein 1 in human umbilical vein endothelium
    (WILEY, 2008) Puebla, Carlos; Farias, Marcelo; Gonzalez, Marcelo; Vecchiola, Andrea; Aguayo, Claudio; Krause, Bernardo; Pastor Anglada, Marcal; Casanello, Paola; Sobrevia, Luis
    High D-glucose reduces human equilibrative nucleoside transporter 1 (hENT1)-mediated adenosine uptake involving endothelial nitric oxide synthase (eNOS), mitogen-activated protein (MAP) kinase kinases 1 and 2/MAP kinases p42/44 (MEK/ERKs), and protein kinase C (PKC) activation in human umbilical vein endothelium (HUVEC). Since NO represses SLC29A1 gene (hENT1) promoter activity we studied whether D-glucose-reduced hENT1-adenosine transport results from lower SLC29A1 expression in HUVEC primary cultures. HUVEC incubation (24 h) with high D-glucose (25 mM) reduced hENT1-adenosine transport and pGL3-hENT1(-1114) construct SLC29A1 reporter activity compared with normal D-glucose (5 mM). High D-glucose also reduced pGL3-hENT1(-1114) reporter activity compared with cells transfected with pGL3-hENT1(-795) Construct. N-G-nitro-L-arginine methyl ester (L-NAME, NOS inhibitor), PD-98059 (MEK1/2 inhibitor), and/or calphostin C (PKC inhibitor) blocked D-glucose effects. Insulin(1 nM) and phorbol 12-myristate 13-acetate (PMA, 100 nM, PKC activator), but not 4 alpha-phorbol 12,13-didecanoate (4 alpha PDD, 100 nM, PMA less active analogue) reduced hENT1-adenosine transport. L-NAME and PD-98059 blocked insulin effects. L-NAME, PD-98059, and calphostin C increased hENT1 expression without altering protein or mRNA stability. High D-glucose increased Sp1 transcription factor protein abundance and binding to SLC29A1 promoter, phenomena blocked by L-NAME, PD-98059, and calphostin C. Sp1 overexpression reduced SLC29A1 promoter activity in normal D-glucose, an effect reversed by L-NAME and further reduced by S-nitroso-N-acetyl-L,D-penicillamine (SNAP, NO donor) in high D-glucose. Thus, reduced hENT1 -mediated adenosine transport in high D-glucose may result from increased Sp1 binding to SLC29A1 promoter down-regulating hENT1 expression. This phenomenon depends on eNOS, MEK/ERKs, and PKC activity, suggesting potential roles for these molecules in hyperglycemia-associated endothelial dysfunction.
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    Increased expression of the multidrug resistance-associated protein 1 (MRP1) in kidney glomeruli of streptozotocin-induced diabetic rats
    (WALTER DE GRUYTER GMBH, 2011) Quezada, Claudia; Alarcon, Sebastian; Carcamo, Juan G.; Yanez, Alejandro; Casanello, Paola; Sobrevia, Luis; San Martin, Rody
    Oxidative stress has been linked to the podocytopathy, mesangial expansion and progression of diabetic nephropathy. The major cell defence mechanism against oxidative stress is reduced glutathione (GSH). Some ABC transporters have been shown to extrude GSH, oxidised glutathione or their conjugates out of the cell, thus implying a role for these transporters in GSH homeostasis. We found a remarkable expression of mRNA for multidrug resistance-associated proteins (MRP/ABCC) 1, 3, 4 and 5 in rat glomeruli. Three weeks after induction of diabetes in glomeruli of streptozotocin-treated rats, we observed a decline in reduced GSH levels and an increase in the expression and activity of MRP1 (ABCC1). These lower GSH levels were improved by ex vivo treatment with pharmacological inhibitors of MRP1 activity (MK571). We conclude that increased activity of MRP1 in diabetic glomeruli is correlated with an inadequate adaptive response to oxidative stress.
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    Insulin Restores Gestational Diabetes Mellitus Reduced Adenosine Transport Involving Differential Expression of Insulin Receptor Isoforms in Human Umbilical Vein Endothelium
    (AMER DIABETES ASSOC, 2011) Westermeier, Francisco; Salomon, Carlos; Gonzalez, Marcelo; Puebla, Carlos; Guzman Gutierrez, Enrique; Cifuentes, Fredi; Leiva, Andrea; Casanello, Paola; Sobrevia, Luis
    OBJECTIVE-To determine whether insulin reverses gestational diabetes mellitus (GDM)-reduced expression and activity of human equilibrative nucleoside transporters 1 (hENT1) in human umbilical vein endothelium cells (HUVECs).
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    Insulin restores glucose inhibition of adenosine transport by increasing the expression and activity of the equilibrative nucleoside transporter 2 in human umbilical vein endothelium
    (WILEY, 2006) Munoz, Gonzalo; San Martin, Rody; Farias, Marcelo; Cea, Luis; Vecchiola, Andrea; Casanello, Paola; Sobrevia, Luis
    L-Arginine transport and nitric oxide (NO) synthesis (L-arginine/NO pathway) are stimulated by insulin, adenosine or elevated extracellular D-glucose in human umbilical vein endothelial cells (HUVEC). Adenosine uptake via the human equilibrative nucleoside transporters 1 (hENT1) and 2 (hENT2) has been proposed as a mechanism regulating adenosine plasma concentration, and therefore its vascular effects in human umbilical veins. Thus, altered expression and/or activity of hENT1 or hENT2 could lead to abnormal physiological plasma adenosine level. We have characterized insulin effect on adenosine transport in HUVEC cultured in normal (5 mM) or high (25, mM) D-glucose. Insulin (1 nM) increased overall adenosine transport associated with higher hENT2-, but lower hENT1-mediated transport in normal D-glucose. insulin increased hENT2 protein abundance in normal or high D-glucose, but reduced hENT1 protein abundance in normal D-glucose. Insulin did not alter the reduced hENT1 protein abundance, but blocked the reduced hENT1 and hENT2 mRNA expression induced by high D-glucose. Insulin effect on hENT1 mRNA expression in normal D-glucose was blocked by N-G-nitro-L-arginine methyl ester (L-NAME, NO synthase inhibitor) and mimicked by S-nitroso-N-acetyl-L,D-penicillamine (SNAP, NO donor). L-NAME did not block insulin effect on hENT2 expression. In conclusion, insulin stimulation of overall adenosine transport results from increased hENT2 expression and activity via a NO-independent mechanism. These findings could be important in hyperglycemia-associated pathological pregnancies, such as gestational diabetes, where plasma adenosine removal by the endothelium is reduced, a condition that could alter the blood flow from the placenta to the fetus affecting fetus growth and development. J. Cell. Physiol. 209: 826-835, 2006. (c) 2006 Wiley-Liss, Inc.
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    Insulin-Increased L-Arginine Transport Requires A(2A) Adenosine Receptors Activation in Human Umbilical Vein Endothelium
    (PUBLIC LIBRARY SCIENCE, 2012) Guzman Gutierrez, Enrique; Westermeier, Francisco; Salomon, Carlos; Gonzalez, Marcelo; Pardo, Fabian; Leiva, Andrea; Sobrevia, Luis
    Adenosine causes vasodilation of human placenta vasculature by increasing the transport of arginine via cationic amino acid transporters 1 (hCAT-1). This process involves the activation of A(2A) adenosine receptors (A(2A)AR) in human umbilical vein endothelial cells (HUVECs). Insulin increases hCAT-1 activity and expression in HUVECs, and A(2A)AR stimulation increases insulin sensitivity in subjects with insulin resistance. However, whether A(2A)AR plays a role in insulin-mediated increase in L-arginine transport in HUVECs is unknown. To determine this, we first assayed the kinetics of saturable L-arginine transport (1 minute, 37 degrees C) in the absence or presence of nitrobenzylthioinosine (NBTI, 10 mu mol/L, adenosine transport inhibitor) and/or adenosine receptors agonist/antagonists. We also determined hCAT-1 protein and mRNA expression levels (Western blots and quantitative PCR), and SLC7A1 (for hCAT-1) reporter promoter activity. Insulin and NBTI increased the extracellular adenosine concentration, the maximal velocity for L-arginine transport without altering the apparent K-m for L-arginine transport, hCAT-1 protein and mRNA expression levels, and SLC7A1 transcriptional activity. An A2AAR antagonist ZM-241385 blocked these effects. ZM241385 inhibited SLC7A1 reporter transcriptional activity to the same extent in cells transfected with pGL3-hCAT-1(-1606) or pGL3-hCAT-1(-650) constructs in the presence of NBTI + insulin. However, SLC7A1 reporter activity was increased by NBTI only in cells transfected with pGL3-hCAT-1(-1606), and the ZM-241385 sensitive fraction of the NBTI response was similar in the absence or in the presence of insulin. Thus, insulin modulation of hCAT-1 expression and activity requires functional A(2A)AR in HUVECs, a mechanism that may be applicable to diseases associated with fetal insulin resistance, such as gestational diabetes.
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    Insulin-Stimulated L-Arginine Transport Requires SLC7A1 Gene Expression and Is Associated With Human Umbilical Vein Relaxation
    (WILEY, 2011) Gonzalez, Marcelo; Gallardo, Victoria; Rodriguez, Natalia; Salomon, Carlos; Westermeier, Francisco; Guzman Gutierrez, Enrique; Abarzua, Fernando; Leiva, Andrea; Casanello, Paola; Sobrevia, Luis
    Insulin causes endothelium-derived nitric oxide (NO)-dependent vascular relaxation, and increases L-arginine transport via cationic amino acid transporter 1 (hCAT-1) and endothelialNOsynthase (eNOS) expression and activity in human umbilical vein endothelium (HUVEC). We studied insulin effect on SLC7A1 gene (hCAT-1) expression and hCAT-transport activity role in insulin-modulated human fetal vascular reactivity. HUVEC were used for L-arginine transport and L-[H-3] citrulline formation (NOS activity) assays in absence or presence of N-ethylmaleimide (NEM) or L-lysine (L-arginine transport inhibitors). hCAT-1 protein abundance was estimated by Western blot, mRNA quantification by real time PCR, and SLC7A1 promoter activity by Luciferase activity (-1,606 and -650 bp promoter fragments from ATG). Specific protein 1 (Sp1), and total or phosphorylatedeNOSprotein was determined by Western blot. Sp1 activity (at four sites between -177 and -105 bp from ATG) was assayed by chromatin immunoprecipitation (ChIP) and vascular reactivity in umbilical vein rings. Insulin increased hCATs-L-arginine transport, maximal transport capacity (V-max/K-m), and hCAT-1 expression. NEM and L-lysine blocked L-arginine transport. In addition, it was trans-stimulated (similar to 7.8-fold) by L-lysine in absence of insulin, but unaltered (similar to 1.4-fold) in presence of insulin. Sp1 nuclear protein abundance and binding to DNA, and SLC7A1 promoter activity was increased by insulin. Insulin increasedNOsynthesis and caused endothelium-dependent vessel relaxation and reduced U46619-induced contraction, effects blocked by NEM and L-lysine, and dependent on extracellular L-arginine. We suggest that insulin induces human umbilical vein relaxation by increasing HUVEC L-arginine transport via hCATs (likely hCAT-1) most likely requiring Sp1-activated SLC7A1 expression. J. Cell. Physiol. 226: 2916-2924, 2011. (C) 2011 Wiley-Liss, Inc.
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    Nitric oxide reduces adenosine transporter ENT1 gene (SLC29A1) promoter activity in human fetal endotheliurn from gestational diabetes
    (WILEY, 2006) Farias, Marcelo; Martin, Rody San; Puebla, Carlos; Pearson, Jeremy D.; Casado, Javier F.; Pastor Anglada, Marcal; Casanello, Paola; Sobrevia, Luis
    Human umbilical vein endothelial cells (HUVEC) from gestational diabetes exhibit reduced adenosine uptake and increased nitric oxide (NO) synthesis. Adenosine transport via human equilibrative nucleoside transporters 1 (hENT1) is reduced by NO by unknown mechanisms in HUVEC. We examined whether gestational diabetes-reduced adenosine transport results from lower hENT1 gene (SLC29A1) expression. HUVEC from gestational diabetes exhibit reduced SLC29A1 promoter activity when transfected with pGL3-hENT1(-2154) compared with pGL3-hENT1(-1114) constructs, an effect blocked by N-G-nitro-L-arginine methyl ester (L-NAME, NOS inhibitor), but unaltered by S-nitroso-N-acetyl-L,D-penicillamine (SNAP, NO donor). In cells from gestational diabetes transfected with pGL3-hENT1(-2114), L-NAME increased, but SNAP did not alter promoter activity and hENT1 expression. However, in cells from normal pregnancies L-NAME increased, but SNAP reduced promoter activity and hENT1 expression. Adenovirus-silenced eNOS expression increased hENT1 expression and activity in cells from normal or gestational diabetic pregnancies. Thus, reduced adenosine transport may result from downregulation of SLC29A1 expression by NO in HUVEC from gestational diabetes. These findings explain the accumulation of extracellular adenosine detected in cultures of HUVEC from gestational diabetes. In addition, fetal endothelial dysfunction could be involved in the abnormal fetal development and growth seen in gestational diabetes.
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    Nrf2 pre‐recruitment at Enhancer 2 is a hallmark of H2O2‐induced epigenetic transcriptional memory in the HMOX1 gene in human umbilical artery endothelial cells
    (2024) Carrasco‐Wong, Ivo; Längst, Gernot; Sobrevia, Luis; Casanello Toledo, Paola Cecilia
    Maternal obesity (MO) is a significant cause of increased cardiometabolic risk in offspring, who present endothelial dysfunction at birth. Alterations in physiologic and cellular redox status are strongly associated with altered gene regulation in arterial endothelium. However, specific mechanisms by which the pro-oxidant fetal environment in MO could modulate the vascular gene expression and function during the offspring's postnatal life are elusive. We tested if oxidative stress could reprogram the antioxidant-coding gene's response to a pro-oxidant challenge through an epigenetic transcriptional memory (ETM) mechanism. A pro-oxidant double-hit protocol was applied to human umbilical artery endothelial cells (HUAECs) and EA.hy 926 endothelial cell lines. The ETM acquisition in the HMOX1 gene was analyzed by RT-qPCR. HMOX1 mRNA decay was evaluated by Actinomycin-D treatment and RT-qPCR. To assess the chromatin accessibility and the enrichment of NRF2, RNAP2, and phosphorylation at serin-5 of RNAP2, at HMOX1 gene regulatory regions, were used DNase HS-qPCR and ChIP-qPCR assays, respectively. The CpG methylation pattern at the HMOX1 core promoter was analyzed by DNA bisulfite conversion and Sanger sequencing. Data were analyzed using two-way ANOVA, and p < 0.05 was statistically significant. Using a pro-oxidant double-hit protocol, we found that the Heme Oxygenase gene (HMOX1) presents an ETM response associated with changes in the chromatin structure at the promoter and gene regulatory regions. The ETM response was characterized by a paused-RNA Polymerase 2 and NRF2 enrichment at the transcription start site and Enhancer 2 of the HMOX1 gene, respectively. Changes in DNA methylation pattern at the HMOX1 promoter were not a hallmark of this oxidative stress-induced ETM. These data suggest that a pro-oxidant milieu could trigger an ETM at the vascular level, indicating a potential epigenetic mechanism involved in the increased cardiovascular risk in the offspring of women with obesity.
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    Potential Role of Sodium-Proton Exchangers in the Low Concentration Arsenic Trioxide-Increased Intracellular pH and Cell Proliferation
    (PUBLIC LIBRARY SCIENCE, 2012) Aravena, Carmen; Beltran, Ana R.; Cornejo, Marcelo; Torres, Viviana; Diaz, Emilce S.; Guzman Gutierrez, Enrique; Pardo, Fabian; Leiva, Andrea; Sobrevia, Luis; Ramirez, Marco A.
    Arsenic main inorganic compound is arsenic trioxide (ATO) presented in solution mainly as arsenite. ATO increases intracellular pH (pHi), cell proliferation and tumor growth. Sodium-proton exchangers (NHEs) modulate the pHi, with NHE1 playing significant roles. Whether ATO-increased cell proliferation results from altered NHEs expression and activity is unknown. We hypothesize that ATO increases cell proliferation by altering pHi due to increased NHEs-like transport activity. Madin-Darby canine kidney (MDCK) cells grown in 5 mmol/L D-glucose-containing DMEM were exposed to ATO (0.05, 0.5 or 5 mu mol/L, 0-48 hours) in the absence or presence of 5-N, N-hexamethylene amiloride (HMA, 5-100 mu mol/L, NHEs inhibitor), PD-98059 (30 mu mol/L, MAPK1/2 inhibitor), Go6976 (10 mu mol/L, PKC alpha, beta I and mu inhibitor), or Schering 28080 (10 mu mol/L, H+/K(+)ATPase inhibitor) plus concanamycin (0.1 mu mol/L, V type ATPases inhibitor). Incorporation of [H-3]thymidine was used to estimate cell proliferation, and counting cells with a hemocytometer to determine the cell number. The pHi was measured by fluorometry in 2,7-bicarboxyethyl-5,6-carboxyfluorescein loaded cells. The Na+-dependent HMA-sensitive NHEs-like mediated proton transport kinetics, NHE1 protein abundance in the total, cytoplasm and plasma membrane protein fractions, and phosphorylated and total p42/44 mitogen-activated protein kinases (p42/44(mapk)) were also determined. Lowest ATO (0.05 mu mol/L, similar to 0.01 ppm) used in this study increased cell proliferation, pHi, NHEs-like transport and plasma membrane NHE1 protein abundance, effects blocked by HMA, PD-98059 or Go6976. Cell-buffering capacity did not change by ATO. The results show that a low ATO concentration increases MDCK cells proliferation by NHEs (probably NHE1)-like transport dependent-increased pHi requiring p42/44(mapk) and PKC alpha, beta I and/or mu activity. This finding could be crucial in diseases where uncontrolled cell growth occurs, such as tumor growth, and in circumstances where ATO, likely arsenite, is available at the drinking-water at these levels. Citation: Aravena C, Beltran AR, Cornejo M, Torres V, Diaz ES, et al. (2012) Potential Role of Sodium-Proton Exchangers in the Low Concentration Arsenic Trioxide-Increased Intracellular pH and Cell Proliferation. PLoS ONE 7(12): e51451. doi:10.1371/journal.pone.0051451