Please use this identifier to cite or link to this item:
http://hdl.handle.net/11375/19514
Full metadata record
DC Field | Value | Language |
---|---|---|
dc.contributor.advisor | Bédard, P.A. | - |
dc.contributor.author | Wang, Lizhen | - |
dc.date.accessioned | 2016-06-10T15:49:45Z | - |
dc.date.available | 2016-06-10T15:49:45Z | - |
dc.date.issued | 2010-05 | - |
dc.identifier.uri | http://hdl.handle.net/11375/19514 | - |
dc.description.abstract | <p> Proper gene expression programs cellular activities, while aberrant manipulation of transcription factors often leads to devastating consequences, such as cancer or cell death. The transcription factor family activator protein-1 (AP-1) plays an important role in many cellular activities including cell transformation, proliferation and survival (Shaulian and Karin 2002). However, little has been done to obtain a global view of the role of individual AP-1 members and how they cooperate in many cellular activities. We have discovered that blocking the AP-1 pathway by a c-Jun dominant negative mutant, TAM67, induced cell death in RSV-transformed primary chicken embryo fibroblasts (CEF), suggesting that AP-1 activity is vital for cell survival upon v-Src transformation. In addition, accumulation of cytoplasmic vesicles was observed in the cytoplasm of a proportion of RSV-transformed CEF expressing TAM67. Oil-red staining of these vesicles indicated the presence of lipid droplets in these cells, suggesting that the inhibition of AP-1 promotes the adipogenic conversion of v-Src transformed CEF. To understand the role of individual members of the AP-1 family, a retroviral-based shRNA expressing system was designed to stably downregulate individual AP-1 members. This retroviral-based RNAi system provided sustained gene downregulation of AP-1 family members. Reduction of the c-Jun protein level by shRNA induced senescence in normal CEF, while it modestly downregulated AP-1 activity in RSV -transformed CEF indicating that c-Jun is not the main component of the AP-1 complex in RSV-transformed CEF. Inhibition of JunD expression induced apoptosis and was deleterious to both normal and RSV-transformed CEF, suggesting that JunD is crucial for the survival of CEF. Transient express10n reporter-assays also showed that loss-of-function of JunD by shRNA dramatically repressed AP-1 activity. Hence JunD is the main component of the AP-1 complex that regulates the survival of CEF. Furthermore, we determined that loss of JunD expression resulted in an elevated level of tumour suppressor p53. Co-inhibition of p53 and JunD restored the transforming ability of v-Src transformed CEF, as indicated by foci formation in soft agar assays. Hence, repression of p53 induction was able to bypass the death signal released as a result of AP-1 inhibition in v-Src transformed CEF. Downregulation of Fra-2 (Fos-related antigen 2) level by shRNA did not affect the proliferation of normal CEF. However, RSV -transformed CEFs expressing fra -2 shRNA were transformation-defective with the presence of multiple vesicles in cytoplasm. Oil-red staining of these vesicles indicated the presence of lipid droplets, which resembles the effect of T AM67 in RSV -transformed CEF indicating that Fra-2 blocks differentiation. These findings help us to understand the role of individual members of the AP-1 transcription factor family in normal and RSV -transformed CEF. Importantly, global gene profiling of v-Src transformed CEF expressing shRNA for individual AP-1 members will improve our knowledge of the transformation process. Functional characterization of the cascade will rely on the use of retroviral-based shRNA expressing system as described above. </p> | en_US |
dc.language.iso | en | en_US |
dc.subject | activator protein-1 | en_US |
dc.subject | RSV-transformed CEF | en_US |
dc.subject | chicken embryonic fibroblast | en_US |
dc.subject | transcription factor family | en_US |
dc.subject | retroviral-based shRNA | en_US |
dc.subject | gene downregulation | en_US |
dc.title | Role of activator protein-1 (AP-1) family in RSV-transformed chicken embryonic fibroblasts (CEF) | en_US |
dc.contributor.department | Biology | en_US |
dc.description.degreetype | Thesis | en_US |
dc.description.degree | Doctor of Philosophy (PhD) | en_US |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
Wang_Lizhen_2010_May_Phd.pdf | 74.42 MB | Adobe PDF | View/Open |
Items in MacSphere are protected by copyright, with all rights reserved, unless otherwise indicated.