Genomes and Genes
Protein Nitration in the Placenta
Principal Investigator: Leslie Myatt
Abstract: Nitration of protein tyrosine residues by the pro-oxidant peroxynitrite is a prevalent, functionally significant post- translation modification leading to either a gain or loss of protein function and alterations in cellular activity. We have demonstrated nitration of many placental proteins including p53, taurine transporter, P2X4 receptor and p38MAP kinase and that the extent of nitration is increased in pregnancies complicated by preeclampsia. The oxidative stress of pregnancy is increased further in preeclampsia where we identified increased placental expression of NADPH oxidase (NOX) enzyme isoforms that produce superoxide and increased eNOS expression in vascular endothelial cells and syncytiotrophoblast. In preeclampsia there is mitochondrial dysfunction and increased trophoblast apoptosis, via downregulation of anti-apoptotic proteins including Bcl-2 and up-regulation of pro-apoptotic p53. The specific mitochondrial NOS isoform, mtNOS, generates NO which at low concentrations inactivates the hemoprotein cytochrome c oxidase to regulate mitochondrial respiration and cellular function. At higher concentrations NO forms peroxynitrite which damages mitochondria causing release of cytochrome c and apoptosis. Nitration of mitochondrial proteins is a reversible process dependent on oxygen concentration hence the hypoxic environment or ischemia/reperfusion of the preeclamptic placenta may cause protein nitration and altered cellular respiration and placental function. This proposal will study the role of protein nitration in regulation of placental mitochondrial function and trophoblast apoptosis utilizing ex vivo and in vitro approaches in human placental tissue and trophoblast cell culture. We will describe the nitroproteome in isolated heavy (syncytiotrophoblast) and light (cytotrophoblast) mitochondrial fractions, comparing tissues from normal pregnancies with mild late onset or severe early onset preeclampsia. Expression of nitrated mitochondrial proteins will be related to activity of mitochondrial enzyme complexes and apoptotic molecules. The involvement of the mtNOS, eNOS and iNOS isoforms, NOX enzymes and manganese superoxide dismutase in nitration and the role of hypoxia and hypoxia/reoxygenation on protein nitration and the apoptotic cascade (P53, caspase 3 and Bcl-2) will be investigated using pharmacologic, knockdown by siRNA and overexpression approaches in trophoblast cell culture. PUBLIC HEALTH RELEVANCE: Preeclampsia is a major problem in obstetrics affecting 7% of pregnancies and being the leading cause of fetal growth restriction, indicated preterm delivery and maternal death particularly with early onset severe disease. The maternal syndrome of preeclampsia appears to be linked to inadequate trophoblast invasion, placental hypoxia and oxidative stress and increased trophoblast apoptosis and shedding into the maternal vasculature. This proposal will test the hypothesis that oxidative and nitrative stress occur in placental mitochondria leading to protein nitration, a covalent modification that alters protein and thus mitochondrial and placental function which is critical to the development of preeclampsia.
Funding Period: -------------------- - --------------------
more information: NIH RePORT
- Expression of NADPH oxidase isoform 1 (Nox1) in human placenta: involvement in preeclampsiaX L Cui
Department of Obstetrics and Gynecology, University of Cincinnati College of Medicine, PO Box 670526, 231 Albert Sabin Way, Cincinnati, OH 45267 0526, USA
Placenta 27:422-31. 2006..Western blot analysis of whole placental homogenate confirmed this increase. Our data suggests that increased Nox1 expression is associated with the increased oxidative stress found in these placentas...
- Post-Translational Modifications of the P2X(4) purinergic receptor subtype in the human placenta are altered in preeclampsiaV H J Roberts
Department of Obstetrics and Gynecology, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267 0526, USA
Placenta 28:270-7. 2007..We also propose that the post-translational modifications of nitration and glycosylation are required for the normal functioning of P2X(4)...
- Protein nitration in placenta - functional significanceR P Webster
Department of Obstetrics and Gynecology, University of Cincinnati, College of Medicine, PO Box 670526, Cincinnati, OH 45267, USA
Placenta 29:985-94. 2008..The targets and extent of nitration of enzymes, receptors, transporters and structural proteins may markedly influence placental cellular function in both physiologic and pathologic settings...
- MIR-210 modulates mitochondrial respiration in placenta with preeclampsiaS Muralimanoharan
Center for Pregnancy and Newborn Research, Dept of Ob Gyn, University of Texas Health Science Center, San Antonio, TX 78229, USA
Placenta 33:816-23. 2012..These data collectively suggest that miR-210 overexpression during PE could be responsible for placental mitochondria dysfunction...
- Evidence of sexual dimorphism in the placental function with severe preeclampsiaS Muralimanoharan
Center for Pregnancy and Newborn Research, Dept of Ob Gyn, University of Texas Health Science Center San Antonio, San Antonio, TX 78229, USA
Placenta 34:1183-9. 2013..We propose that the transcription factor NFκB p65 might, at least partially, be involved in sexual dimorphism during PE. ..
- Effect of increasing maternal body mass index on oxidative and nitrative stress in the human placentaV H J Roberts
Department of Obstetrics and Gynecology, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267 0526, USA
Placenta 30:169-75. 2009..There may be a shift in the balance between nitrative and oxidative stress, which may be a protective mechanism for the placenta...
- Loss of proliferative capacity in a retroviral immortalized human uterine smooth muscle cell line derived from leiomyoma is restored by hTERT overexpressionBaoJun Chang
Department of Obstetrics and Gynecology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA
Reprod Sci 16:1062-71. 2009..Our finding suggests that ULTR-hT cells can be a useful in vitro model for studying human myometrium differentiation both in pregnancy and pathological growth...
- Review: Reactive oxygen and nitrogen species and functional adaptation of the placentaL Myatt
Department of Obstetrics and Gynecology, Center for Pregnancy and Newborn Research, University of Texas Health Science Center San Antonio, Mail Code 7836, 7703 Floyd Curl Drive, San Antonio, TX 78229 3900, USA
Placenta 31:S66-9. 2010..As protein carbonylation is a covalent modification at Lys, Arg, Pro and Thr residues the switch from carbonylation to nitration at tyrosine residues may alter protein function and hence placental function...
- Measurement of mitochondrial respiration in trophoblast cultureA Maloyan
Center for Pregnancy and Newborn Research, Department of Obstetrics and Gynecology, University of Texas Health Science Center San Antonio, Mail Code 7836, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
Placenta 33:456-8. 2012..However, this does not provide a complete physiological readout of mitochondrial function. This technical note describes a method to measure respiratory function in intact primary syncytiotrophoblast from human term placenta...