Global ETD Search

1	Aberrant DNA Replication at an Ectopic Chromosomal Site in Human Cells Chen, Xiaomi 27 April 2011 (has links) No description available. Biomedical Research Replication c-myc replicator GAL4 fusion protein induction of replication origin activity pre-replication complex isogenic cell lines FLP recombinase system DM1 triplet repeat instability zinc finger nuclease hairpin formation.
2	Investigarion of Activated Phosphaidylinositol 3’ Kinase Signaling in Stem Cell Self-renewal and Tumorigenesis Ling, Ling 31 August 2012 (has links) The phosphatidylinositol 3' kinase (PI3K) pathway is involved in many cellular processes including cell proliferation, survival, and glucose transport, and is implicated in various disease states such as cancer and diabetes. Though there have been numerous studies dissecting the role of PI3K signaling in different cell types and disease models, the mechanism by which PI3K signaling regulates embryonic stem (ES) cell fate remains unclear. It is believed that in addition to proliferation and tumorigenicity, PI3K activity might also be important for self-renewal of ES cells. Paling et al. (2004) reported that the inhibition of PI3K led to a reduction in the ability of leukemia inhibitory factor (LIF) to maintain self-renewal causing cells to differentiate. Studies in our lab have revealed that ES cells completely lacking GSK-3 remain undifferentiated compared to wildtype ES cells. GSK-3 is negatively regulated by PI3K suggesting that PI3K may play a vital role in maintaining pluripotency in ES cells through GSK-3. By using a modified Flp recombinase system, we expressed activated alleles of PDK-1 and PKB to create stable, isogenic ES cell lines to further study the role of the PI3K signaling pathway in stem cell fate determination. In vitro characterization of the transgenic cell lines revealed a strong tendency towards maintenance of pluripotency, and this phenotype was found to be independent of canonical Wnt signal transduction. To assess growth and differentiation capacity in vivo, the ES cell lines were grown as subcutaneous teratomas. The constitutively active PDK-1 and PKB ES cell lines were able to form all three germ layers when grown in this manner – in contrast to ES cells engineered to lack GSK-3. The resulting PI3K pathway activated cells exhibited a higher growth rate which resulted in large teratomas. In summary, PI3K signaling is sufficient to maintain self-renewal and survival of stem cells. Since this pathway is frequently mutationally activated in cancers, its effect on suppressing differentiation may contribute to its oncogenicity. PI3K pathway PDK1 myr-PDK1 PKB PKB-DD GSK-3 p70S6K β-catenin Axin-2 Wnt pathway embyronic stem cells pluripotency self-renewal Oct-4 cell fate differentiation embryoid bodies teratoma formation tumorigenesis Akti-1/2 mTOR rapamycin endothelial cells vascularization proliferation apoptosis Flp-In system isogenic cell lines signal transduction myristoylation phosphomimetic 0307 0379
3	Investigarion of Activated Phosphaidylinositol 3’ Kinase Signaling in Stem Cell Self-renewal and Tumorigenesis Ling, Ling 31 August 2012 (has links) The phosphatidylinositol 3' kinase (PI3K) pathway is involved in many cellular processes including cell proliferation, survival, and glucose transport, and is implicated in various disease states such as cancer and diabetes. Though there have been numerous studies dissecting the role of PI3K signaling in different cell types and disease models, the mechanism by which PI3K signaling regulates embryonic stem (ES) cell fate remains unclear. It is believed that in addition to proliferation and tumorigenicity, PI3K activity might also be important for self-renewal of ES cells. Paling et al. (2004) reported that the inhibition of PI3K led to a reduction in the ability of leukemia inhibitory factor (LIF) to maintain self-renewal causing cells to differentiate. Studies in our lab have revealed that ES cells completely lacking GSK-3 remain undifferentiated compared to wildtype ES cells. GSK-3 is negatively regulated by PI3K suggesting that PI3K may play a vital role in maintaining pluripotency in ES cells through GSK-3. By using a modified Flp recombinase system, we expressed activated alleles of PDK-1 and PKB to create stable, isogenic ES cell lines to further study the role of the PI3K signaling pathway in stem cell fate determination. In vitro characterization of the transgenic cell lines revealed a strong tendency towards maintenance of pluripotency, and this phenotype was found to be independent of canonical Wnt signal transduction. To assess growth and differentiation capacity in vivo, the ES cell lines were grown as subcutaneous teratomas. The constitutively active PDK-1 and PKB ES cell lines were able to form all three germ layers when grown in this manner – in contrast to ES cells engineered to lack GSK-3. The resulting PI3K pathway activated cells exhibited a higher growth rate which resulted in large teratomas. In summary, PI3K signaling is sufficient to maintain self-renewal and survival of stem cells. Since this pathway is frequently mutationally activated in cancers, its effect on suppressing differentiation may contribute to its oncogenicity. PI3K pathway PDK1 myr-PDK1 PKB PKB-DD GSK-3 p70S6K β-catenin Axin-2 Wnt pathway embyronic stem cells pluripotency self-renewal Oct-4 cell fate differentiation embryoid bodies teratoma formation tumorigenesis Akti-1/2 mTOR rapamycin endothelial cells vascularization proliferation apoptosis Flp-In system isogenic cell lines signal transduction myristoylation phosphomimetic 0307 0379

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