Thesis (Ph. D.)--University of Texas Southwestern Medical Center at Dallas, 2008. / Vita. Includes bibliographical references (p. 163-183).

Hydroxyurea was used as a model teratogen to investigate the role of oxidative stress and stress-response pathways in mediating developmental toxicity. When administered to pregnant mice during early organogenesis, hydroxyurea induced fetal death and growth retardation, as well as external and skeletal malformations. The malformed fetuses displayed hindlimb, vertebral column, and tail defects. Hydroxyurea treatment enhanced the production of 4-hydroxynonenal, a lipid peroxidation end product, in malformation sensitive regions of the embryo. Depletion of glutathione, a major cellular antioxidant, specifically enhanced hydroxyurea-induced malformations and elevated the region-specific production of 4--hydroxynonenal protein adducts in the embryo, without affecting the incidence or extent of hydroxyurea-induced fetal death or growth retardation. The major proteins modified by 4-hydroxynonenal were involved in energy metabolism. Thus, oxidative stress is important in the induction of malformations by hydroxyurea. / Exposure to hydroxyurea stimulated the DNA binding activity of activator protein 1 (AP-1), an early response redox-sensitive transcription factor. Activated AP-1 was composed mainly of c-Fos heterodimers. Glutathione depletion did not change the effects of hydroxyurea on AP-1/c-Fos DNA binding activities despite an augmentation of the incidence of embryo malformations. Mitogen-activated protein kinases (MAPKs) activate AP-1 in response to stress by post-transcriptional phosphorylation of AP-1 proteins. Hydroxyurea treatment dramatically enhanced the activation of stress-responsive p38 MAPKs and JNKs (c-Jun N-terminal protein kinases). Selectively blocking p38 MAPKs enhanced the incidence of fetal death, whereas selective inhibition of JNKs specifically elevated the limb defects induced by hydroxyurea. Thus, activation of stress-response pathways impacts on the response of the embryo to a teratogenic insult.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2005. / Härtill 4 uppsatser.

No description available.

Existem evidências que o hormônio adrenocorticotrópico (ACTH) tem um papel importante no equilíbrio entre proliferação e morte celular na glândula supra-renal. As proteínas dos genes de resposta primária, proteínas da família Fos e Jun são componentes do fator de transcrição AP1, que dependendo de sua composição, pode estar relacionado com proliferação, diferenciação ou morte celular. Nesse trabalho utilizamos culturas de células primárias de adrenal de ratos para avaliar por imunocitoquímica e por imunoblotting, os efeitos do ACTH e do FGF2, na expressão das proteínas c-Fos, FosB, Fra1, Fra2, c-Jun, JunB e JunD. Os resultados mostram que tratamentos com ACTH e FGF2 modificam o padrão de expressão dessas proteínas. O ACTH induz aumento consistente da expressão de JunB, o que sugere uma composição de AP1 formada por JunB/c-Fos ou FosB. Tratamentos com FGF2, indicam a formação de um complexo c-Jun/c-Fos, FosB e Fra2. Esses resultados estão de acordo com os efeitos biológicos observados da ação do ACTH e do FGF2, como, inibição e proliferação celular nessas células. / There are evidences that in vivo the adrenocorticotropic hormone (ACTH) displays an important role in the balance of proliferation and cellular death in the adrenal gland. The early response gene proteins, Fos and Jun family, are components of the transcription factor AP-1 that, depending on its composition, could be related with proliferation, differentiation or cellular death. In this work we have been used adrenocortex cells of rat primary cultures, to evaluate, by immunocytochemistry and immunoblotting, the effects of ACTH and FGF2, in the expression of c-Fos, FosB, Fra1, Fra2, c-Jun, JunB and JunD proteins, and in such wise as to predict the composition of AP1 complex. The results showed that ACTH and FGF2 treatments modify the expression pattern of these proteins, inducing consistent and expressive increase of JunB expression in the ACTH-treated cells, suggesting an AP1 composition with JunB/c-Fos or FosB. FGF2 treatments indicate the composition of c-Jun/c-Fos or FosB or Fra-2 complexes. These results are in agreement with the biological effects observed in rat adrenal primary culture treated with ACTH and FGF2, with inhibition and cellular proliferation.

Existem evidências que o hormônio adrenocorticotrópico (ACTH) tem um papel importante no equilíbrio entre proliferação e morte celular na glândula supra-renal. As proteínas dos genes de resposta primária, proteínas da família Fos e Jun são componentes do fator de transcrição AP1, que dependendo de sua composição, pode estar relacionado com proliferação, diferenciação ou morte celular. Nesse trabalho utilizamos culturas de células primárias de adrenal de ratos para avaliar por imunocitoquímica e por imunoblotting, os efeitos do ACTH e do FGF2, na expressão das proteínas c-Fos, FosB, Fra1, Fra2, c-Jun, JunB e JunD. Os resultados mostram que tratamentos com ACTH e FGF2 modificam o padrão de expressão dessas proteínas. O ACTH induz aumento consistente da expressão de JunB, o que sugere uma composição de AP1 formada por JunB/c-Fos ou FosB. Tratamentos com FGF2, indicam a formação de um complexo c-Jun/c-Fos, FosB e Fra2. Esses resultados estão de acordo com os efeitos biológicos observados da ação do ACTH e do FGF2, como, inibição e proliferação celular nessas células. / There are evidences that in vivo the adrenocorticotropic hormone (ACTH) displays an important role in the balance of proliferation and cellular death in the adrenal gland. The early response gene proteins, Fos and Jun family, are components of the transcription factor AP-1 that, depending on its composition, could be related with proliferation, differentiation or cellular death. In this work we have been used adrenocortex cells of rat primary cultures, to evaluate, by immunocytochemistry and immunoblotting, the effects of ACTH and FGF2, in the expression of c-Fos, FosB, Fra1, Fra2, c-Jun, JunB and JunD proteins, and in such wise as to predict the composition of AP1 complex. The results showed that ACTH and FGF2 treatments modify the expression pattern of these proteins, inducing consistent and expressive increase of JunB expression in the ACTH-treated cells, suggesting an AP1 composition with JunB/c-Fos or FosB. FGF2 treatments indicate the composition of c-Jun/c-Fos or FosB or Fra-2 complexes. These results are in agreement with the biological effects observed in rat adrenal primary culture treated with ACTH and FGF2, with inhibition and cellular proliferation.

5-Bromo-2'-deoxyuridine (BrdU), a thymidine analogue, is genotoxic and teratogenic. The exposure of mouse embryos to BrdU at doses that cause malformations induces oxidative stress and an embryonic stress response characterized by an increase in c-Fos dependent AP-1 DNA binding. The goal of this thesis was to test the hypothesis that development is disturbed at sites where BrdU is incorporated into DNA, triggering oxidative stress and c-Fos induction. Gestation day 9 CD-1 mice were treated with BrdU and embryos were obtained for immunolocalization of BrdU, 8-oxoguanine, a biomarker for oxidative stress, and c-Fos. BrdU incorporation into DNA was dispersed throughout the embryo. In contrast, the staining for 8-oxoguanine and c-Fos were highest in the neuroepithelium. BrdU incorporation was not affected by the pre-administration of N-acetyl-cysteine (NAC), an anti-oxidant, although both 8-oxoguanine and c-Fos staining were decreased. Thus, the response of the embryo to insult is tissue specific.

Thesis (Ph. D.) -- University of Texas Southwestern Medical Center at Dallas, 2005. / Vita. Bibliography: 106-116.

The c-Jun NH2-terminal kinases (JNK) are evolutionarily conserved serine/threonine protein kinases that are activated by proinflammatory cytokines, environmental stress, and genotoxic agents. These kinases play key regulatory roles within a cell by coordinating signals from the cell surface to nuclear transcription factors. JNK phosphorylates the amino terminal domain of all three Jun transcription factors (JunB, c-Jun and JunD) all members of the AP-1 family. The activated transcription factors modulate gene expression to generate appropriate biological responses, including cell migration, proliferation, differentiation and cell death. The role of the JNK signaling pathway in cell death/apoptosis is controversial, both pro-apoptotic and pro-survival roles have been attributed to JNK. The mechanism that enables the JNK signaling pathway to mediate both apoptosis and survival is unclear. The aim of this study is to examine the role of TNF-stimulated JNK activation on cell survival. The proinflammatory cytokine TNF, is known to activate JNK and induce apoptosis. To test whether the JNK signaling pathway contributes to TNF-induced apoptosis, the response of wild type and Jnk1-/- Jnk2-/- (JNK deficient fibroblasts) fibroblasts to TNF was examined. JNK deficient fibroblasts are more sensitive to TNF-induced apoptosis than wild-type fibroblasts. The TNF-sensitivity cannot be attributed to altered expression of TNF receptors or defects in the NF-кB or AKT pathways, known anti-apoptotic signal transduction pathways. (In fact, TNF stimulated NF-кB activation provides a major mechanism to account for survival in both wild-type and JNK deficient cells.) However this increased TNF-sensitivity can be attributed to JNK deficiency. Apoptosis is suppressed in JNK deficient cells when transduced with JNK1 retrovirus. These data implicate the JNK signaling pathway in cell survival. The AP-1 family of transcription factors is a target of the JNK signal transduction pathway. In addition JNK is required for the normal expression of the AP-1 family member, JunD. Previous studies have indicated that JunD can mediate survival. Interestingly, JNK deficient and JunD null cells display similar phenotypes: premature senescence and increased sensitivity to TNF induced apoptosis. In fact, the TNF-sensitivity is also suppressed in JNK deficient fibroblasts transduced with JunD retrovirus. Although JunD can replace the survival signaling role of JNK, phosphorylation of JunD is essential to inhibit TNF induced apoptosis. JNK deficient cells transduced with phosphomutant JunD retrovirus maintain TNF-sensitivity. Activated transcription factors modulate gene expression. It is most likely that JunD functions by regulating the expression of key molecules that act to inhibit TNF-stimulated apoptosis. Microarray analysis comparing wild-type with JNK deficient fibroblasts revealed that the expression of the survival gene, cIAP-2, was induced by TNF in only wild-type fibroblasts. Furthermore, protein expression of cIAP-2 was induced by TNF in only wild-type fibroblasts. Analysis of the cIAP-2 promoter revealed two critical NF-кB binding sites and one AP-1 binding site. Luciferase reporter assays indicated key roles for both NF-кB and the AP-1 component, JunD in TNF-induced cIAP-2 gene expression. These experiments establish that the JNK/JunD pathway collaborates with NF-кB pathway to increase the expression of the anti-apoptotic protein cIAP-2 in TNF treated cells. Without this collaboration, the JNK pathway mediates apoptosis. The integration of JNK signaling with other signaling pathways represents a mechanism to account for the dual ability of the JNK pathway to mediate either survival or apoptosis. The dynamic coordination of signals within and between pathways is critical. The future challenge will be to fit the details of individual signaling pathways into the context of signaling networks.

No description available.