Project description:Notch signaling regulates several cellular processes including cell fate decisions and proliferation in both invertebrates and mice. However, comparatively less is known about the role of Notch during early human development. Here, we examined the function of Notch signaling during hematopoietic lineage specification from human pluripotent stem cells (hPSCs) of both embryonic and adult fibroblast origin. Using immobilized Notch ligands and siRNA to Notch receptors we have demonstrated that Notch1, but not Notch2 activation, induced HES1 expression and generation of committed hematopoietic progenitors. Using gain and loss of function approaches, this was shown to be attributed to Notch signaling regulation through HES1, that dictated cell fate decisions from bipotent precursors either to the endothelial or hematopoietic lineages at the clonal level. Our study reveals a previously unappreciated role for the Notch pathway during early human hematopoiesis, whereby Notch signaling via HES1 represents a toggle switch of hematopoietic vs. endothelial fate specification.
Project description:Notch signaling regulates several cellular processes including cell fate decisions and proliferation in both invertebrates and mice. However, comparatively less is known about the role of Notch during early human development. Here, we examined the function of Notch signaling during hematopoietic lineage specification from human pluripotent stem cells (hPSCs) of both embryonic and adult fibroblast origin. Using immobilized Notch ligands and siRNA to Notch receptors we have demonstrated that Notch1, but not Notch2 activation, induced HES1 expression and generation of committed hematopoietic progenitors. Using gain and loss of function approaches, this was shown to be attributed to Notch signaling regulation through HES1, that dictated cell fate decisions from bipotent precursors either to the endothelial or hematopoietic lineages at the clonal level. Our study reveals a previously unappreciated role for the Notch pathway during early human hematopoiesis, whereby Notch signaling via HES1 represents a toggle switch of hematopoietic vs. endothelial fate specification. Human pluripotent stem cells (hPSCs) have differentiation potential into three embryonic germ layers including blood. Notch signaling is one of important signaling pathways involved in blood differentiation of hPSCs. Thus, in order to examine the effect of Notch signaling pathways during hematopoietic differentiation of hPSCs, embryoid bodies (EBs) were formed and cultured for 10 days in the combination of cytokines and growth factors (Chadwick, Blood, 2003; 300 ng/ml of SCF, 300 ng/ml of Flt-3L, 10 ng/ml of IL-3, 10 ng/ml of IL-6, and 50 ng/ml of G-CSF) to induce differentiation into blood. Additionally, CD31+CD45- bipotent hemogenic precursors were isolated from day10 hematopoietic EBs (Wang et al., Immunity, 2004)
Project description:ER71 mutant embryos are nonviable and lack hematopoietic and endothelial lineages. To further define the functional role for ER71 in cell lineage decisions, we generated genetically modified mouse models. We engineered an ER71-EYFP transgenic mouse model by fusing the 3.9 kb ER71 promoter to the EYFP reporter gene. Using FACS and transcriptional profiling, we examined the EYFP+ populations of cells in ER71 mutant and wildtype littermates. In the absence of ER71, we observed an increase in the number of EYFP expressing cells, increased expression of the cardiac molecular program and decreased expression of the hemato-endothelial program compared to the wildtype littermate controls. We have also generated a novel ER71-Cre transgenic mouse model using the same 3.9 kb ER71 promoter. Genetic fate mapping studies revealed that the ER71 expressing cells daughter hematopoietic and endothelial lineages in the wildtype background. In the absence of ER71, these cell populations contributed to alternative mesodermal lineages including the cardiac lineage. To extend these analyses, we used an inducible ES/EB system and observed that ER71 overexpression repressed cardiogenesis. Together, these studies identify ER71 as a critical regulator of mesodermal fate decisions, acting to specify the hematopoietic and endothelial lineages at the expense of cardiac lineages. This enhances our understanding of the mechanisms that govern mesodermal fate decisions early during embryogenesis. 12samples were analyzed, including triplicates of WT; EYFP positive, WT EYFP negative, ER71 MT; EYFP positive and ER71 MT; EYFP negative cells
Project description:ER71 mutant embryos are nonviable and lack hematopoietic and endothelial lineages. To further define the functional role for ER71 in cell lineage decisions, we generated genetically modified mouse models. We engineered an ER71-EYFP transgenic mouse model by fusing the 3.9 kb ER71 promoter to the EYFP reporter gene. Using FACS and transcriptional profiling, we examined the EYFP+ populations of cells in ER71 mutant and wildtype littermates. In the absence of ER71, we observed an increase in the number of EYFP expressing cells, increased expression of the cardiac molecular program and decreased expression of the hemato-endothelial program compared to the wildtype littermate controls. We have also generated a novel ER71-Cre transgenic mouse model using the same 3.9 kb ER71 promoter. Genetic fate mapping studies revealed that the ER71 expressing cells daughter hematopoietic and endothelial lineages in the wildtype background. In the absence of ER71, these cell populations contributed to alternative mesodermal lineages including the cardiac lineage. To extend these analyses, we used an inducible ES/EB system and observed that ER71 overexpression repressed cardiogenesis. Together, these studies identify ER71 as a critical regulator of mesodermal fate decisions, acting to specify the hematopoietic and endothelial lineages at the expense of cardiac lineages. This enhances our understanding of the mechanisms that govern mesodermal fate decisions early during embryogenesis.
Project description:Dll4-Notch signaling is required for cell fate decisions and neoplasias. However, emerging evidence suggests a role for Dll4-Notch signaling in metabolic and immune diseases. To date, there is no evidence of a direct effect of Dll4-Notch signaling inhibition on pancreatic islet function and insulin secretion.
Project description:Induced pluripotent stem cells (iPSC) offer a promising platform to model early embryonic developmental processes, to create disease models and proof-of-concept experiments for regenerative medicine. However, generation of iPSC derived hemato-endothelial and hematopoietic progenitor cells for these applications is challenging due to variable and limited cell numbers, which necessitates enormous up-scaling or development of demanding protocols. Here, we unravel the function of key transcriptional regulators SCL, LMO2, GATA2, ETV2 (SLGE) on early hemato-endothelial specification and establish a fully inducible and stepwise hemato-endothelial forward programming system, based on SLGE regulated overexpression. Regulated induction of SLGE in stable SLGE-iPSC lines drives very efficient generation of large numbers of hemato-endothelial progenitor cells (HEP) (CD144+/CD73-), which generate hematopoietic progenitor cells (CD45+/CD34+/CD38-/CD45RA-/CD90+/CD49f+) through a gradual process of endothelial-to-hematopoietic transition (EHT).
Project description:The Notch pathway is a conserved cell-cell communication pathway that controls cell fate decisions. Here we sought to determine how Notch pathway activation inhibits the neuroendocrine cell fate in the lungs, an archetypal process for cell fate decisions orchestrated by Notch signaling that has remained poorly understood at the molecular level. Using heterogeneity in small cell lung cancer as a model system, we uncovered a role for the transcriptional regulators REST and YAP as promoters of the neuroendocrine to non-neuroendocrine transition. We further identified the specific neuroendocrine gene programs repressed by REST downstream of Notch in this process. Importantly, we validated the importance of REST and YAP in neuroendocrine to non-neuroendocrine cell fate switches in both developmental and tissue repair processes in the lungs. Altogether, these experiments identify conserved roles for REST and YAP in Notch-driven inhibition of the neuroendocrine cell fate in embryonic lungs, adult lungs, and lung cancer.
Project description:The Notch pathway is a conserved cell-cell communication pathway that controls cell fate decisions. Here we sought to determine how Notch pathway activation inhibits the neuroendocrine cell fate in the lungs, an archetypal process for cell fate decisions orchestrated by Notch signaling that has remained poorly understood at the molecular level. Using heterogeneity in small cell lung cancer as a model system, we uncovered a role for the transcriptional regulators REST and YAP as promoters of the neuroendocrine to non-neuroendocrine transition. We further identified the specific neuroendocrine gene programs repressed by REST downstream of Notch in this process. Importantly, we validated the importance of REST and YAP in neuroendocrine to non-neuroendocrine cell fate switches in both developmental and tissue repair processes in the lungs. Altogether, these experiments identify conserved roles for REST and YAP in Notch-driven inhibition of the neuroendocrine cell fate in embryonic lungs, adult lungs, and lung cancer.
Project description:The Notch pathway is a conserved cell-cell communication pathway that controls cell fate decisions. Here we sought to determine how Notch pathway activation inhibits the neuroendocrine cell fate in the lungs, an archetypal process for cell fate decisions orchestrated by Notch signaling that has remained poorly understood at the molecular level. Using heterogeneity in small cell lung cancer as a model system, we uncovered a role for the transcriptional regulators REST and YAP as promoters of the neuroendocrine to non-neuroendocrine transition. We further identified the specific neuroendocrine gene programs repressed by REST downstream of Notch in this process. Importantly, we validated the importance of REST and YAP in neuroendocrine to non-neuroendocrine cell fate switches in both developmental and tissue repair processes in the lungs. Altogether, these experiments identify conserved roles for REST and YAP in Notch-driven inhibition of the neuroendocrine cell fate in embryonic lungs, adult lungs, and lung cancer.
Project description:The Notch pathway is a conserved cell-cell communication pathway that controls cell fate decisions. Here we sought to determine how Notch pathway activation inhibits the neuroendocrine cell fate in the lungs, an archetypal process for cell fate decisions orchestrated by Notch signaling that has remained poorly understood at the molecular level. Using heterogeneity in small cell lung cancer as a model system, we uncovered a role for the transcriptional regulators REST and YAP as promoters of the neuroendocrine to non-neuroendocrine transition. We further identified the specific neuroendocrine gene programs repressed by REST downstream of Notch in this process. Importantly, we validated the importance of REST and YAP in neuroendocrine to non-neuroendocrine cell fate switches in both developmental and tissue repair processes in the lungs. Altogether, these experiments identify conserved roles for REST and YAP in Notch-driven inhibition of the neuroendocrine cell fate in embryonic lungs, adult lungs, and lung cancer.