ORCID Profile
0000-0003-1013-1883
Current Organisation
University of Miami School of Medicine
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Publisher: Springer Science and Business Media LLC
Date: 15-06-2008
DOI: 10.1038/NMETH.1222
Abstract: The mode of ligand presentation has a fundamental role in organizing cell fate throughout development. We report a rapid and simple approach for immobilizing signaling ligands to maleic anhydride copolymer thin-film coatings, enabling stable signaling ligand presentation at interfaces at defined concentrations. We demonstrate the utility of this platform technology using leukemia inhibitory factor (LIF) and stem cell factor (SCF). Immobilized LIF supported mouse embryonic stem cell (mESC) pluripotency for at least 2 weeks in the absence of added diffusible LIF. Immobilized LIF activated signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinase (MAPK) signaling in a dose-dependent manner. The introduced method allows for the robust investigation of cell fate responses from interface-immobilized ligands.
Publisher: Proceedings of the National Academy of Sciences
Date: 13-03-2007
Abstract: Tetraploid embryo complementation assay has shown that mouse ES cells alone are capable of supporting embryonic development and adult life of mice. Newly established F 1 hybrid ES cells allow the production of ES cell-derived animals at a high enough efficiency to directly make ES cell-based genetics feasible. Here we report the establishment and characterization of 12 new F 1 hybrid ES cell lines and the use of one of the best (G4) in a gain- and loss-of-function genetic study, where the in vivo phenotypes were assessed directly from ES cell-derived embryos. We found the generation of G4 ES cell-derived animals to be very efficient. Furthermore, even after two consecutive rounds of genetic modifications, the majority of transgenic lines retained the original potential of the parental lines with 10–40% of chimeras producing ES cell-derived animals/embryos. Using these genetically altered ES cells, this success rate, in most cases, permitted the derivation of a sufficient number of mutants for initial phenotypic analyses only a few weeks after the establishment of the cell lines. Although the experimental design has to take into account a moderate level of uncontrolled damage on ES cell lines, our proof-of-principle experiment provides useful data to assist future designs harnessing the power of this technology to accelerate our understanding of gene function.
Publisher: Oxford University Press (OUP)
Date: 04-09-2008
DOI: 10.1634/STEMCELLS.2008-0237
Abstract: Vascular endothelial growth factor (VEGF) and the vascular endothelial growth factor receptors (VEGFRs) regulate the development of hemogenic mesoderm. Oxygen concentration-mediated activation of hypoxia-inducible factor targets such as VEGF may serve as the molecular link between the microenvironment and mesoderm-derived blood and endothelial cell specification. We used controlled-oxygen microenvironments to manipulate the generation of hemogenic mesoderm and its derivatives from embryonic stem cells. Our studies revealed a novel role for soluble VEGFR1 (sFlt-1) in modulating hemogenic mesoderm fate between hematopoietic and endothelial cells. Parallel measurements of VEGF and VEGFRs demonstrated that sFlt-1 regulates VEGFR2 (Flk-1) activation in both a developmental-stage-dependent and oxygen-dependent manner. Early transient Flk-1 signaling occurred in hypoxia because of low levels of sFlt-1 and high levels of VEGF, yielding VEGF-dependent generation of hemogenic mesoderm. Sustained (or delayed) Flk-1 activation preferentially yielded hemogenic mesoderm-derived endothelial cells. In contrast, delayed (sFlt-1-mediated) inhibition of Flk-1 signaling resulted in hemogenic mesoderm-derived blood progenitor cells. Ex vivo analyses of primary mouse embryo-derived cells and analysis of transgenic mice secreting a Flt-1-Fc fusion protein (Fc, the region of an antibody which is constant and binds to receptors) support a hypothesis whereby microenvironmentally regulated blood and endothelial tissue specification is enabled by the temporally variant control of the levels of Flk-1 activation. Disclosure of potential conflicts of interest is found at the end of this article.
Publisher: American Society of Clinical Oncology (ASCO)
Date: 03-2020
DOI: 10.1200/JCO.19.01907
Abstract: To estimate age-specific relative and absolute cancer risks of breast cancer and to estimate risks of ovarian, pancreatic, male breast, prostate, and colorectal cancers associated with germline PALB2 pathogenic variants (PVs) because these risks have not been extensively characterized. We analyzed data from 524 families with PALB2 PVs from 21 countries. Complex segregation analysis was used to estimate relative risks (RRs relative to country-specific population incidences) and absolute risks of cancers. The models allowed for residual familial aggregation of breast and ovarian cancer and were adjusted for the family-specific ascertainment schemes. We found associations between PALB2 PVs and risk of female breast cancer (RR, 7.18 95% CI, 5.82 to 8.85 P = 6.5 × 10 −76 ), ovarian cancer (RR, 2.91 95% CI, 1.40 to 6.04 P = 4.1 × 10 −3 ), pancreatic cancer (RR, 2.37 95% CI, 1.24 to 4.50 P = 8.7 × 10 −3 ), and male breast cancer (RR, 7.34 95% CI, 1.28 to 42.18 P = 2.6 × 10 −2 ). There was no evidence for increased risks of prostate or colorectal cancer. The breast cancer RRs declined with age ( P for trend = 2.0 × 10 −3 ). After adjusting for family ascertainment, breast cancer risk estimates on the basis of multiple case families were similar to the estimates from families ascertained through population-based studies ( P for difference = .41). On the basis of the combined data, the estimated risks to age 80 years were 53% (95% CI, 44% to 63%) for female breast cancer, 5% (95% CI, 2% to 10%) for ovarian cancer, 2%-3% (95% CI females, 1% to 4% 95% CI males, 2% to 5%) for pancreatic cancer, and 1% (95% CI, 0.2% to 5%) for male breast cancer. These results confirm PALB2 as a major breast cancer susceptibility gene and establish substantial associations between germline PALB2 PVs and ovarian, pancreatic, and male breast cancers. These findings will facilitate incorporation of PALB2 into risk prediction models and optimize the clinical cancer risk management of PALB2 PV carriers.
Location: United States of America
No related grants have been discovered for Sophia George.