Autumn and Changya will Present their Research on Thursday, 8-6-15
CALCIUM DEPENDENT NAKED-DISHEVELLED INTERACTION MODULATES WNT SIGNALING OUTPUTS
Autumn N, Marsden1,2, Sarah W. Derry1, Trudi A. Westfall1, Diane C. Slusarski1
1Department of Biology, University of Iowa, Iowa City, IA 52242, 2Interdisciplinary Graduate Program in Genetics
The Wnt signaling network plays critical roles in development and is implicated in disease. Wnt signaling gives rise to two distinct outputs: polarized cell movement (Wnt/PCP) and stabilization of β-catenin (Wnt/β-catenin). The mechanisms that determine the output is not completely understood, especially because of shared upstream effectors. My project focuses on two shared components that also bind each other, Dishevelled (Dvl) and Naked (Nkd), an EF-hand containing protein. We have demonstrated that Nkd is required for dorsal forerunner cell (DFC) migration, Kupffer’s vesicle formation and proper organ laterality. Using biochemical and functional assays, we show calcium-induced conformational changes in the Nkd-Dvl complex and identify a requirement for the Nkd EF-hand in PCP but not β-catenin outputs. We predict that Nkd and Dvl form a cooperative calcium binding pocket, which allows for conformational changes or subcellular localization to direct Wnt/PCP output. To determine the impact upon Wnt signaling output, I utilize gene knockdown and overexpression in the DFCs, a tissue that has dynamic calcium fluxes and hosts converging Wnt signals. I also determined the subcellular localization of Nkd and Dvl components within the DFCs and cells that are calcium quiescent. Our data suggests that calcium-induced secondary structure changes in the Nkd-Dvl complex serve to interpret the physiology of a cell receiving multiple cues and provides mechanistic insight into Wnt signal integration in vivo.
The Epigenetic Landscape and Promoter-Interactome during Development of Hematopoietic Stem Cells
Hematopoietic Stem Cells (HSCs) are derived from in fetal liver (FL) undergo rapid self-renewal divisions, which lead to a massive increase in cell number of the HSC pool. In contrast, the adult bone marrow (BM) HSCs have lower self-renewal capacity. In addition, FL and BM HSCs display differences in their differentiated cell output. FL HSCs have a biased erythro-myeloid lineage output while BM HSCs have balanced lineage output. These differences of biological properties between FL and BM HSCs correlate with distinct gene expression programs. Our RNA-Seq analysis has shown that about 1600 genes are differentially expressed between FL HSCs and BM HSCs. It is also well known that gene expression is regulated by cis-regulatory element. Detailed studies for single loci have revealed some mechanisms how cis-regulatory elements regulate gene expression. However, genome-wide long-range enhancer-promoter interactomes in FL and BM HSCs are still not well studied. We have generated histone modification profilings (H3K4Me1, H3K4Me3, H3K27me3, and H3K27Ac) for both FL and BM HSCs by ChIP-Seq. Based on histone modification profilings, we predicted more than ten thousands active enhancers in both FL and BM HSCs using our computational method: CSI-ANN. Combined our RNA-Seq, we predicted Enhancer-Promoter interactions using IM-PET. To further address research question, we are using Capture-C, a chromosome conformation capture-based technology to generate genome-wide promoter interactomes in both FL and BM HSCs. We will integrate these datasets to understand how differences in the promoter interactomes contribute to the gene expression programs, and then contribute to the phenotypic difference between FL and BM HSCs.