Figure 2

Enrichment analysis of functional groups within the stem cell-derived cardiopoietic transcriptome. (a) Approximately half of all expression profiles in cardiopoietic cells are downregulated while a third do not change more than 1.5-fold compared to unstimulated embryonic stem cells. Upregulated genes account for >10% of all genes. (b, c) Ontological analysis of downregulated and upregulated biological processes in cardiopoietic cells. (d, e) Identification of overrepresented canonical functions in cardiopoietic cells (CP) using Ingenuity Pathways Analysis (IPA) in downregulated and upregulated gene lists. Significance as determined by IPA was plotted as log P value for downregulated genes and -log P value for those upregulated to emphasize direction of change. The dashed line indicates the threshold where the P value = 0.05. Embryonic stem cells in the presence of mitogenic LIF were taken as baseline and significant functional enrichment in cardiopoietic cells are shown in comparison with stem cells cultured without LIF. (f) Gene validation using quantitative PCR. Candidate genes representing pluripotent (Pou5f1), oncogenic (Mybl2, Mycn) and cardiac (Myocd, Lbh) phenotypes were assayed by Taqman. Transcriptional profile changes were expressed as fold change relative to ES-LIF(+). CM, cardiomyocyte.