Browsing by Author "Leiva, Andrea "

Now showing 1 - 9 of 9
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    Altered Chemokine Receptor Expression in Papillary Thyroid Cancer
    (MARY ANN LIEBERT, INC, 2009) Gonzalez, Hernan E.; Leiva, Andrea; Tobar, Hugo; Boehmwald, Karen; Tapia, Grace; Torres, Javiera; Mosso, Lorena M.; Bueno, Susan M.; Gonzalez, Pablo; Kalergis, Alexis M.; Riedel, Claudia A.
    Background: Papillary thyroid cancer (PTC), the most prevalent type of differentiated thyroid carcinoma, displays a strikingly high frequency of lymph node metastasis (LNM). Recent data suggest that chemokines can play an important role in promoting tumor progression and metastatic migration of tumor cells. Here we have evaluated whether PTC tissues express a different pattern of chemokine receptors and if the expression of these receptors correlates with LNM.
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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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    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-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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    PDZK1 is required for maintaining hepatic scavenger receptor, class B, type I (SR-BI) steady state levels but not its surface localization or function
    (AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 2006) Yesilaltay, Ayce; Kocher, Olivier; Pal, Rinku; Leiva, Andrea; Quinones, Veronica; Rigotti, Attilio; Krieger, Monty
    PDZK1 is a multi-PDZ domain-containing adaptor protein that binds to the C terminus of the high density lipoprotein receptor, scavenger receptor, class B, type I (SR-BI), and controls the posttranscriptional, tissue-specific expression of this lipoprotein receptor. In the absence of PDZK1 (PDZK1(-/-) mice), murine hepatic SR-BI protein levels are very low (< 5% of control). As a consequence, abnormal plasma lipoprotein metabolism (similar to 1.5-1.7-fold increased total plasma cholesterol carried in both normal size and abnormally large high density lipoprotein particles) resembles, but is not as severely defective as, that in SR-BI(-/-) mice. Here we show that the total plasma cholesterol levels and size distribution of lipoproteins are virtually identical in SR-BI(-/-) and SR-BI(-/-)/ PDZK1(-/-) mice, indicating that most, if not all of the effects of PDZK1 on lipoprotein metabolism are likely because of the effects of PDZK1 on SR-BI. Hepatic overexpression of wild-type SR-BI in PDZK1(-/-) mice restored near or greater than normal levels of cell surface-expressed, functional SR-BI protein levels in the livers of SR-BI(-/-)/ PDZK1(-/-) mice and consequently restored apparently normal lipoprotein metabolism in the absence of PDZK1. Thus, PDZK1 is important for maintaining adequate steady state levels of SR-BI in the liver but is not essential for cell surface expression or function of hepatic SR-BI.
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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