Depending on the context, both mechanisms may either compete or act together to fix DSBs in eukaryotic cells. Unlike HR where rejoining of the DNA ends requires the presence of a homologous template and is mainly important during the late S and G that the time course for DSB repair in primary human fibroblasts is independent of the initial dose of X-rays for values grater than Supporting Information January Energy-Dependent Apoptosis significant developmental anomalies in mice and humans. Despite the importance of GPCRs in development, with the exception of the Frizzled receptors, the role of GPCRs in ES cell pluripotency and differentiation has received little attention. Since GPCRs are readily targetable sites for small molecules, as evidenced by their role as drug targets in humans, characterization of GPCRs and related signaling molecules in ES cells may facilitate developing new approaches to ES cell differentiation. Given that, one of the goals of this study was to examine GPCR expression in ES cells. GPCRs signal through,February GPCR Signaling in Stem Cells data mining of RNA expression libraries. These studies demonstrated for the first time expression of novel GPCRs in undifferentiated and differentiated ES cells and, in some cases, differential expression during ES cell differentiation. We also tested whether signaling through Gs-alpha plays a role in ES 
cell biology finding that Gs-alpha activation leads to large embryoid bodies, in part by enhancing the proliferation rate of cells within EBs. We also tested whether signaling through Gs-alpha impacts ES cell pluripotency and differentiation, and demonstrated that this G protein signaling pathway alters the expression of transcription factors important for maintaining ES cell pluripotency. Markers Nanog Oct Forward Methods ES Cell Culture The R doi: medium without or with CTX. Drops were placed and allowed to grow for Quantification of Embryoid Body Size EBs were examined every February GPCR Signaling in Stem Cells Real Time RT-PCR Cells were isolated and lysed using Trizol reagent. Total RNA was isolated, DNA removed by DNAase I digestion, and cDNA was prepared with the iScript cDNA synthesis kit. Samples were run at a GPCR RNA Arrays which allows the expression of mRNAs encoding GPCRs from February GPCR Signaling in Stem Cells Family PACAP Adenosine Gene Adcyap Fold Change Family Orphans Gene Gpr Fold Change Family Chemokine Gene Ccr Fold Change Lysophospholipid Edg Angiotensin Adrenoceptor Agtr Glutamate Grm Thrombin Frizzled Endothelin Glucagon F Vasopressin CCr Calcitonin Cadherin Acetylcholine Celsr Orexin Histamine Hcrt Orphans Gpr Cannaboid Dopamine Endothelin Frizzled Cnr Serotonin Htr Kisspeptins Leucine-rich Kiss GABA Gabbr Leukotriene Somatostatin Prostanoid Free fatty acid Mass Glucagon Ghsr Gipr Melanocortin Mc Orphans Gpr Neuropeptide FF Npffr GPCRs that showed a greater than GPCRs that showed a greater than undetectable. In these instances, for data processing purposes, the cycle number was set at from Cell Signaling, except for Cilomilast antibodies directed against Nanog, melanocortin- Immunofluorescence Analyses Western Blot Analysis EBs were isolated in RIPA cell lysis buffer containing a cocktail of protease inhibitors at different time points. Primary antibodies were obtained EBs were isolated on different days over a February GPCR Signaling in Stem Cells Gene Gpr Fold Change sectioned every WST-EBs were isolated at the indicated time points, washed once with PBS,