Placental Taurine Transport in Pre-eclampsia

  • Chloe Hirst

    Student thesis: Unknown


    Pre-eclampsia (PE) is a serious disease affecting approximately 5% of pregnancies per annum. The disease etiology is complex but its origin lies in abnormal placental development and function. PE is associated with inflammation, increased nitrative stress and abnormal renewal of syncytiotrophoblast (STB), the transporting epithelium of the placenta. STB is renewed by cytotrophoblasts (CTBs) that proliferate, differentiate and fuse with STB and this is balanced by apoptosis. The amino acid taurine facilitates proliferation, differentiation and apoptosis in non-placental tissues. Taurine is also cytoprotective, protecting cells from damage by inflammatory cytokines. Taurine is transported from maternal blood into STB by the amino acid transporter TauT. In isolated STB membranes, TauT activity is inhibited by agents that nitrate tyrosine residues. This thesis tested the hypothesis that STB TauT activity is down-regulated in PE due to post-translational modification of TauT through tyrosine nitration which lowers intracellular taurine and contributes to altered STB renewal. Placentas were collected from normal pregnancy (NP) and PE (blood pressure >140/90mmHg after 20 weeks gestation in previously normotensive women plus proteinuria >300 mg/L in a 24-hour collection). STB TauT activity, measured as Na+-dependent uptake of 3H-taurine into placental villous fragments, was significantly lower in PE (n=24) compared to NP (n=44). Western blotting of membrane enriched homogenates showed that TauT protein expression (normalised to β-actin) was significantly higher in placentas from PE (n=8) compared to NP (n=9). The presence of nitrotyrosine residues (marker of nitrative stress) in placentas of women with PE and NP was assessed by immunohistochemistry (IHC). The intensity of STB nitrotyrosine staining was greater in PE placentas that had reduced TauT activity (n=8) than in NP (n=7). To determine the effect of nitrative stress on TauT activity and STB renewal, placental villous explants from NP were cultured (7 days; n=6) and treated with SIN-1 (1mM; days 5,6) to induce nitrative stress. STB nitrotyrosine (IHC) and TauT activity (3H-taurine uptake) was determined on day 7 and STB renewal was assessed by IHC for apoptosis (M30), proliferation (dual staining for Ki67 and the CTB marker E-cadherin) and STB integrity (cytokeratin 7). SIN-1 increased STB nitrotyrosine staining intensity compared to controls, confirming induction of nitrative stress. SIN-1 reduced STB TauT activity, increased apoptosis, reduced CTB proliferation and altered STB regeneration compared to control. To determine the effect of reducing intracellular taurine on STB renewal, villous explants were cultured for 7 days with 2.5mM β-alanine to competitively inhibit taurine uptake (n=6). At day 7, intracellular taurine, measured as the steady-state accumulation of 3H-taurine, was 15% of normal. STB turnover was assessed at day 7 as described above. β-alanine significantly increased apoptosis and altered STB regeneration compared to controls. Following statistical analysis all p
    Date of Award1 Aug 2015
    Original languageEnglish
    Awarding Institution
    • The University of Manchester
    SupervisorSusan Greenwood (Supervisor) & Michelle Desforges (Supervisor)


    • Pregnancy
    • Nitrative stress
    • Amino acid transport
    • Pre-eclampsia
    • Placenta
    • Taurine

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