Maria Ibarra-Sanchez
Research interests
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Interestsdeficient primary fibroblasts, TC-PTP single knockout, Breast Cancer, receptor tyrosine kinases
Publications
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2.06Impact points
Oxidative stress and apoptosis are induced in human endothelial cells exposed to urban particulate matter.
Toxicology in vitro : an international journal published in association with BIBRA. 09/2009;
Correlations between exposure to particle matter (PM) with an aerodynamic diameter 2.5 or 10 mum (PM(2.5) and PM(10), respectively) with cardiovascular effects have been demonstrated recently. Endothelial cells seem to play a relevant role in the responses to PM due to their participation in pro-inf... [more] Correlations between exposure to particle matter (PM) with an aerodynamic diameter 2.5 or 10 mum (PM(2.5) and PM(10), respectively) with cardiovascular effects have been demonstrated recently. Endothelial cells seem to play a relevant role in the responses to PM due to their participation in pro-inflammatory events. In this study we determined the effect of PM(2.5) and PM(10) from Mexico City on human endothelial cells by means of evaluating reactive oxygen species (ROS), nitric oxide (NO), NF-kappaB translocation and cell death. For this purpose we used human umbilical vein endothelial cells (HUVEC) as a model. The production of ROS was determined by the reduction of H(2)DCFDA and NO by Griess reagent. The translocation of NF-kappaB was evaluated by Electrophoretic Mobility Shift Assay (EMSA) and the cellular death by the translocation of phosphatidylserine. TNF-alpha was used as a positive control for endothelial cell activation. PM(2.5) and PM(10) induced the production of ROS (77% and 126% increase, respectively, vs. control) and NO (up to 132% and 233% increase, respectively, vs. control). PM(2.5) and PM(10) also induced the nuclear translocation of NF-kappaB. All these events were associated with apoptosis. In conclusion, the activation of HUVEC induced by PM(2.5) and PM(10) is related with an oxidative stress, suggesting that these particles may participate in the development of cardiovascular and inflammatory diseases.
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Dehydroepiandrosterone delays LDL oxidation in vitro and attenuates several oxLDL-induced inflammatory responses in endothelial cells.
Inflammation & allergy drug targets. 10/2007; 6(3):174-82.
Dehydroepiandrosterone (DHEA) has a protective role against atherosclerosis, most likely mediating an anti-inflammatory action. In order to understand the mechanisms involved in this protection, we evaluated the effects of DHEA on several molecules involved in the inflammatory response. Reactive oxy... [more] Dehydroepiandrosterone (DHEA) has a protective role against atherosclerosis, most likely mediating an anti-inflammatory action. In order to understand the mechanisms involved in this protection, we evaluated the effects of DHEA on several molecules involved in the inflammatory response. Reactive oxygen species (ROS), expression of adhesion molecules, activation of the NF-kappaB/IkappaB-alpha pathway and of the AP-1 transcription factor were evaluated in human umbilical vein endothelial cells (HUVECs) treated with oxidized low density lipoproteins (oxLDL) and DHEA. We also determined if DHEA affected LDL oxidation in vitro. 100 microM DHEA-treatment inhibited the oxLDL-induced expression of ICAM-1, VCAM-1, PECAM-1, ROS production, and U937 cells adhesion to HUVECs. DHEA also delayed the kinetics of LDL oxidation in vitro. While DHEA did not affect the translocation of NF-kappaB neither the degradation IkappaB-alpha, it led to an increased translocation of AP-1. Our results suggest that DHEA inhibits the expression of molecules involved in the inflammatory process in endothelial cells activated with oxLDL, therefore its potential anti-inflammatory properties should be evaluated for the treatment of chronic inflammatory diseases such as atherosclerosis.
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5.65Impact points
Gr-1+ myeloid cells lacking T cell protein tyrosine phosphatase inhibit lymphocyte proliferation by an IFN-gamma- and nitric oxide-dependent mechanism.
Journal of immunology (Baltimore, Md. : 1950). 08/2003; 171(2):726-32.
The T cell protein tyrosine phosphatase is involved in the immune system regulation, as evidenced by defective function and development of several hemopoietic cell populations in T cell protein tyrosine phosphatase (TC-PTP)-deficient mice. In particular, B and T cell proliferation is greatly inhibit... [more] The T cell protein tyrosine phosphatase is involved in the immune system regulation, as evidenced by defective function and development of several hemopoietic cell populations in T cell protein tyrosine phosphatase (TC-PTP)-deficient mice. In particular, B and T cell proliferation is greatly inhibited when total splenocytes are stimulated by LPS or anti-CD3 mAb. To define the functional defect of TC-PTP(-/-) lymphocytes, we isolated T and B cells from the spleen of TC-PTP(-/-) mice. We show that the proliferative response of lymphocytes was greatly increased when cultured as a purified population, indicating that an inhibitory population is present in TC-PTP(-/-) spleen. However, TC-PTP(-/-) lymphocytes have a 2- to 3-fold lower proliferation rate compared with TC-PTP(+/+) lymphocytes, suggesting that, as shown previously in embryonic fibroblasts, TC-PTP is involved in the control of cell cycle in lymphocytes. We have characterized phenotypically and functionally the inhibitory population present in the spleen of TC-PTP(-/-) mice. We show that a Gr-1(+)-enriched cell population isolated from TC-PTP(-/-) mice suppresses the CD3-induced proliferation of T cells in coculture in vitro. The specific inhibition of NO synthesis with N(G)-monomethyl-L-arginine.monoacetate restored splenocyte responses, and there is a strict correlation between NO levels and the degree of suppression. Neutralization of IFN-gamma with specific mAb almost completely abolished the inhibitory activity of Gr-1(+) cells and concomitantly high levels of NO secretion. Moreover, inhibition of lymphocyte proliferative responses required cell-cell contact to achieve sufficient levels of NO. These findings demonstrate an important function of TC-PTP in the induction of the NO pathway that mediates inhibition of T cell proliferation.
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6.06Impact points
Protein tyrosine phosphatase 1B attenuates growth hormone-mediated JAK2-STAT signaling.
Molecular and cellular biology. 07/2003; 23(11):3753-62.
Protein tyrosine phosphatase-1B (PTP-1B) attenuates insulin, PDGF, EGF, and IGF-I signaling by dephosphorylating tyrosine residues located in the tyrosine kinase domain of the corresponding receptors. More recently, PTP-1B was shown to modulate the action of cytokine signaling via the nonreceptor ty... [more] Protein tyrosine phosphatase-1B (PTP-1B) attenuates insulin, PDGF, EGF, and IGF-I signaling by dephosphorylating tyrosine residues located in the tyrosine kinase domain of the corresponding receptors. More recently, PTP-1B was shown to modulate the action of cytokine signaling via the nonreceptor tyrosine kinase JAK2. Transmission of the growth hormone (GH) signal also depends on JAK2, raising the possibility that PTP-1B modulates GH action. Consistent with this hypothesis, GH increased the abundance of tyrosine-phosphorylated JAK2 associated with a catalytically inactive mutant of PTP-1B. GH-induced JAK2 phosphorylation was greater in knockout (KO) than in wild-type (WT) PTP-1B embryonic fibroblasts and resulted in increased tyrosine phosphorylation of STAT3 and STAT5, while overexpression of PTP-1B reduced the GH-mediated activation of the acid-labile subunit gene. To evaluate the in vivo relevance of these observations, mice were injected with GH under fed and fasted conditions. As expected, tyrosine phosphorylation of JAK2 and STAT5 occurred readily in the livers of fed WT mice and was almost completely abolished during fasting. In contrast, resistance to the action of GH was severely impaired in the livers of fasted KO mice. These results indicate that PTP-1B regulates GH signaling by reducing the extent of JAK2 phosphorylation and suggest that PTP-1B is essential for limiting the action of GH during metabolic stress such as fasting.
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6.06Impact points
Identification of a nuclear Stat1 protein tyrosine phosphatase.
Molecular and cellular biology. 09/2002; 22(16):5662-8.
Upon interferon (IFN) stimulation, Stat1 becomes tyrosine phosphorylated and translocates into the nucleus, where it binds to DNA to activate transcription. The activity of Stat1 is dependent on tyrosine phosphorylation, and its inactivation in the nucleus is accomplished by a previously unknown pro... [more] Upon interferon (IFN) stimulation, Stat1 becomes tyrosine phosphorylated and translocates into the nucleus, where it binds to DNA to activate transcription. The activity of Stat1 is dependent on tyrosine phosphorylation, and its inactivation in the nucleus is accomplished by a previously unknown protein tyrosine phosphatase (PTP). We have now purified a Stat1 PTP activity from HeLa cell nuclear extract and identified it as TC45, the nuclear isoform of the T-cell PTP (TC-PTP). TC45 can dephosphorylate Stat1 both in vitro and in vivo. Nuclear extracts lacking TC45 fail to dephosphorylate Stat1. Furthermore, the dephosphorylation of IFN-induced tyrosine-phosphorylated Stat1 is defective in TC-PTP-null mouse embryonic fibroblasts (MEFs) and primary thymocytes. Reconstitution of TC-PTP-null MEFs with TC45, but not the endoplasmic reticulum (ER)-associated isoform TC48, rescues the defect in Stat1 dephosphorylation. The dephosphorylation of Stat3, but not Stat5 or Stat6, is also affected in TC-PTP-null cells. Our results identify TC45 as a PTP responsible for the dephosphorylation of Stat1 in the nucleus.
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Oxidative stress and apoptosis are induced in human endothelial cells exposed to urban particulate matter
Toxicology in Vitro.
Correlations between exposure to particle matter (PM) with an aerodynamic diameter ⩽ 2.5 or 10 μm (PM2.5 and PM10, respectively) with cardiovascular effects have been demonstrated recently. Endothelial cells seem to play a relevant role in the responses to PM due to their participation in pro-inflam... [more] Correlations between exposure to particle matter (PM) with an aerodynamic diameter ⩽ 2.5 or 10 μm (PM2.5 and PM10, respectively) with cardiovascular effects have been demonstrated recently. Endothelial cells seem to play a relevant role in the responses to PM due to their participation in pro-inflammatory events. In this study we determined the effect of PM2.5 and PM10 from Mexico City on human endothelial cells by means of evaluating reactive oxygen species (ROS), nitric oxide (NO), NF-κB translocation and cell death. For this purpose we used human umbilical vein endothelial cells (HUVEC) as a model.The production of ROS was determined by the reduction of H2DCFDA and NO by Griess reagent. The translocation of NF-κB was evaluated by Electrophoretic Mobility Shift Assay (EMSA) and the cellular death by the translocation of phosphatidylserine. TNF-α was used as a positive control for endothelial cell activation.PM2.5 and PM10 induced the production of ROS (77% and 126% increase, respectively, vs. control) and NO (up to 132% and 233% increase, respectively, vs. control). PM2.5 and PM10 also induced the nuclear translocation of NF-κB. All these events were associated with apoptosis. In conclusion, the activation of HUVEC induced by PM2.5 and PM10 is related with an oxidative stress, suggesting that these particles may participate in the development of cardiovascular and inflammatory diseases.
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Biochemical and cellular function of t-cell protein tyrosine phosphatase
Tyrosine phosphorylation is one of the most important post-translational modifications used by cells to respond to external stimuli. Two different sets of enzymes control the tyrosine phosphorylation levels of proteins: the protein tyrosine kinases and the protein tyrosine phosphatases. The identifi... [more] Tyrosine phosphorylation is one of the most important post-translational modifications used by cells to respond to external stimuli. Two different sets of enzymes control the tyrosine phosphorylation levels of proteins: the protein tyrosine kinases and the protein tyrosine phosphatases. The identification of the cellular function of these enzymes is a key step in the understanding of many biological processes, such as proliferation, differentiation and apoptosis. We used a mouse model deficient in the protein tyrosine phosphatase TC-PTP to identify its biological and biochemical functions. Analysis of the phenotype of murine embryonic fibroblasts from TC-PTP-/- embryos revealed that TC-PTP-/- cells have an impaired proliferation due to a slow progression during the early G1-phase of the cell cycle. In these cells, there is a delayed expression of cyclin D1 through a defective IKK/NF-kappaB signaling pathway. These data confirmed that TC-PTP plays a positive role in cell proliferation. In the second part of this thesis, I studied the putative role of TC-PTP in response to DNA damage. I demonstrated that mice and cells lacking TC-PTP have a high sensitivity to genotoxic stress, which seems to be associated with an increased stability and elevated phosphorylation of serine-15 of the tumor suppressor p53. We found that the p53 inhibitor, Mdm2 is highly tyrosine phosphorylated in TC-PTP-/- cells. High tyrosine phosphorylation levels on Mdm2 are associated with more stability of p53. Although, it was not possible to show that Mdm2 is a direct substrate for TC-PTP, this seems to be the most likely mechanism used by TC-PTP to control p53. Interestingly, I also showed that double deficient mice for both TC-PTP and p53 live longer and display a normal spleen compared with the TC-PTP single knockout. However, another phenotype like the anemia is not rescued in the double knockout mice. Murine embryonic fibroblasts from TC-PTP-/- p53-/- embryos also have a better survival after genotoxic stress when compared with the TC-PTP-/- cells. Thus, we propose that TC-PTP plays a role in response to DNA damage by affecting the tyrosine phosphorylation levels of Mdm2, and its associated increased stability of the tumor suppressor p53 In the last part of my thesis, I tested the genetic interaction between the protein kinase c-Abl and the protein tyrosine phosphatase TC-PTP. Taking in account the knockout phenotypes of both enzymes, we generated double deficient mice for both TC-PTP and cAbl. TC-PTP-/- c-Abl-/- mice are viable, but there was no difference in the time of survival of these animals when compared with the single knockouts. However, data obtained with primary fibroblasts indicated that indeed there is a genetic interaction between TC-PTP and c-Abl. Double deficient primary fibroblasts proliferate better than TC-PTP-/- cells, and also present a better survival in response to genotoxic stress. The induction of p53 is also reduced in comparison with TC-PTP-/- cells. These results indicate that a genetic interaction between both enzymes exists and that this phenomenon is likely to be resulting from the existence of at least one common substrate.
