The role of the mitochondrial thioredoxin-2 system in cell function

Persistent Link:
http://hdl.handle.net/10150/289903
Title:
The role of the mitochondrial thioredoxin-2 system in cell function
Author:
Nonn, Larisa
Issue Date:
2003
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The hypothesis upon which this research is based is that the mitochondrial thioredoxin-2 system, which consists of mitochondrial thioredoxin-2 (Trx-2), mitochondrial thioredoxin reductase (TrxR-2) and mitochondrial thioredoxin peroxidase (Prdx-3), protects cells against apoptosis and regulates cell growth via mitochondrial redox homeostasis. Trx-2 mRNA was found expressed in a panel of cancer cell lines and Trx-2 protein is localized exclusively to the mitochondria. An alternate splice form of Trx-2 lacking exon 2 was identified that does not yield protein. Forced overexpression of Trx-2 in cell lines by using constitutive and inducible promoter systems increased mRNA levels, but did not yield an increase in Trx-2 protein. The role of Trx-2 in mammalian development was examined by generating a mouse deficient in Trx-2. Massive apoptosis, exencephaly and early embryonic lethality was seen in the Trx-2(-/-) homozygous embryos. Trx-2(-/-) embryonic fibroblasts were not viable under normal growth conditions, but could be rescued with maintenance in hypoxia. Trx-2(-/-) cells were also lacking mature cytochrome c, implicating Trx-2 in cytochrome c biogenesis. The Trx-2(+/-) heterozygous mice, which appear normal, had an increased sensitivity to some forms of oxidative toxicity (eg. acute doxorubicin) compared to the wild-type mice. To investigate the role of Prdx-3, WEHI7.2 cells with overexpression of Prdx-3 were generated by stable transfection. Overexpression of Prdx-3 inhibited cell proliferation, reduced cellular hydrogen peroxide levels and altered the mitochondrial membrane potential. Prdx-3 overexpression protected the cell from various drug-induced and hypoxia-induced apoptosis. Prdx-3 protein degradation was decreased during hypoxia, leading to a longer half-life under hypoxic conditions. Additionally, Prdx-3 protein levels were increased in a RCC4 cells expressing wild-type VHL compared to RCC4 cells with mutant VHL.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Cell.; Health Sciences, Toxicology.; Health Sciences, Pharmacology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Pharmacology and Toxicology
Degree Grantor:
University of Arizona
Advisor:
Powis, Garth

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleThe role of the mitochondrial thioredoxin-2 system in cell functionen_US
dc.creatorNonn, Larisaen_US
dc.contributor.authorNonn, Larisaen_US
dc.date.issued2003en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe hypothesis upon which this research is based is that the mitochondrial thioredoxin-2 system, which consists of mitochondrial thioredoxin-2 (Trx-2), mitochondrial thioredoxin reductase (TrxR-2) and mitochondrial thioredoxin peroxidase (Prdx-3), protects cells against apoptosis and regulates cell growth via mitochondrial redox homeostasis. Trx-2 mRNA was found expressed in a panel of cancer cell lines and Trx-2 protein is localized exclusively to the mitochondria. An alternate splice form of Trx-2 lacking exon 2 was identified that does not yield protein. Forced overexpression of Trx-2 in cell lines by using constitutive and inducible promoter systems increased mRNA levels, but did not yield an increase in Trx-2 protein. The role of Trx-2 in mammalian development was examined by generating a mouse deficient in Trx-2. Massive apoptosis, exencephaly and early embryonic lethality was seen in the Trx-2(-/-) homozygous embryos. Trx-2(-/-) embryonic fibroblasts were not viable under normal growth conditions, but could be rescued with maintenance in hypoxia. Trx-2(-/-) cells were also lacking mature cytochrome c, implicating Trx-2 in cytochrome c biogenesis. The Trx-2(+/-) heterozygous mice, which appear normal, had an increased sensitivity to some forms of oxidative toxicity (eg. acute doxorubicin) compared to the wild-type mice. To investigate the role of Prdx-3, WEHI7.2 cells with overexpression of Prdx-3 were generated by stable transfection. Overexpression of Prdx-3 inhibited cell proliferation, reduced cellular hydrogen peroxide levels and altered the mitochondrial membrane potential. Prdx-3 overexpression protected the cell from various drug-induced and hypoxia-induced apoptosis. Prdx-3 protein degradation was decreased during hypoxia, leading to a longer half-life under hypoxic conditions. Additionally, Prdx-3 protein levels were increased in a RCC4 cells expressing wild-type VHL compared to RCC4 cells with mutant VHL.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Cell.en_US
dc.subjectHealth Sciences, Toxicology.en_US
dc.subjectHealth Sciences, Pharmacology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePharmacology and Toxicologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorPowis, Garthen_US
dc.identifier.proquest3089999en_US
dc.identifier.bibrecord.b44425351en_US
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