The regulation of multipotent cardiac progenitor cell (CPC) expansion and subsequent differentiation into cardiomyocytes, smooth muscle, or endothelial cells is a fundamental aspect of basic cardiovascular biology and cardiac regenerative medicine. However, the mechanisms governing these decisions remain unclear. Here, we show that Wnt/-Catenin signaling, which promotes expansion of CPCs, is negatively regulated by Notch1-mediated control of phosphorylated -Catenin accumulation within CPCs, and that Notch1 activity in CPCs is required for their differentiation. Notch1 positively, and -Catenin negatively, regulated expression of the cardiac transcription factors, Isl1, Myocd and Smyd1. Surprisingly, disruption of Isl1, normally expressed transiently in CPCs prior to their differentiation, resulted in expansion of CPCs in vivo and in an embryonic stem (ES) cell system. Furthermore, Isl1 was required for CPC differentiation into cardiomyocyte and smooth muscle cells, but not endothelial cells. These findings reveal a regulatory network controlling CPC expansion and cell fate that involve unanticipated functions of -Catenin, Notch1 and Isl1 that may be leveraged for regenerative approaches involving CPCs.
A regulatory pathway involving Notch1/beta-catenin/Isl1 determines cardiac progenitor cell fate.
Specimen part
View SamplesGoal of experiment: Identify genes down-regulated between pre- and post-natal stages in mouse dental papillae.
Down-regulated genes in mouse dental papillae and pulp.
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View SamplesDNA damage plays a major role in neural cell death by necrosis and/or apoptosis. However, our understanding of the molecular mechanisms of neural cell death remains still incomplete. To acquire a global understanding of the various mediators related to DNA damage-induced neural cell death pathways, we performed a whole genomic wide screen in neural stem cells by using a siRNA library. We identified 80 genes required for DNA damage-induced cell death. 14 genes (17.5%) are directly related to cell death and/or apoptosis. 66 genes have not been previously directly linked to DNA damage-induced cell death. Using an integrated approach with functional and bioinformatics analysis, we have uncovered a molecular network containing several partially overlapping and interconnected pathways and/or protein complexes that are required for DNA damage-induced neural cell death. The identification of the network of neural cell death mediators will greatly enhance our understanding of the molecular mechanisms of neural cell death and provide therapeutic targets for nervous system disorders.
High-Content Genome-Wide RNAi Screen Reveals <i>CCR3</i> as a Key Mediator of Neuronal Cell Death.
Specimen part, Cell line
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