Project description:The identified stromal factors SDF1alpha, sFRP1 and VEGFD induce dopaminergic neuron differentiation of human pluripotent stem cells. Human embryonic stem cell (hESC)-derived dopaminergic (DA) neurons are potentially useful for treating Parkinson’s disease (PD) through cell replacement therapy. Generation of DA neurons from hESCs has been achieved by co-culture with the stromal cell line PA6, a source of stromal cell-derived inducing activity (SDIA). However, the factor(s) produced by stromal cells that constitute SDIA is unknown. We previously reported that medium conditioned by PA6 cells can generate functional DA neurons in the human embryonal carcinoma stem cell line, NTera2. Here we further examined the effects of PA6-conditioned medium and found that it can induce DA neuronal differentiation in both the NTera2 cell line and the hESC line, I6. To identify the factor(s) responsible for SDIA, we used large-scale microarray analysis of gene expression combined with proteomic analysis of PA6-conditioned medium. Four candidate factors (hepatocyte growth factor (HGF), stromal cell-derived factor-1 alpha (SDF1alpha), secreted frizzled-related protein 1 (sFRP1) and vascular endothelial growth factor D (VEGFD)) were identified and immunoaffinity capillary electrophoresis (ICE) was used to establish the protein concentration of these factors in conditioned medium. Upon addition of SDF1alpha, sFRP1, and VEGFD, we observed an increase in the number of tyrosine hydroxylase- and TuJ1- positive cells in both the NTera2 and I6 cell lines. These results indicate that SDF1alpha, sFRP1 and VEGF-D are major components of SDIA, and suggest the potential use of these defined factors to elicit dopaminergic differentiation of pluripotent stem cells as a therapeutic intervention in PD. Mouse embryonic fibroblasts were grown in DMEM medium supplemented with 10% FBS; this conditioned media was used as the control. PA6, mouse stromal cells, were grown in MEM-alpha supplemented with 10% FBS; this conditioned media is known to induce differentiation in hES cells.

Project description:Chavez2009 - a core regulatory network of OCT4 in human embryonic stem cells A core OCT4-regulated network has been identified as a test case, to analyase stem cell characteristics and cellular differentiation. This model is described in the article: In silico identification of a core regulatory network of OCT4 in human embryonic stem cells using an integrated approach. Chavez L, Bais AS, Vingron M, Lehrach H, Adjaye J, Herwig R BMC Genomics, 2009, 10:314 Abstract: BACKGROUND: The transcription factor OCT4 is highly expressed in pluripotent embryonic stem cells which are derived from the inner cell mass of mammalian blastocysts. Pluripotency and self renewal are controlled by a transcription regulatory network governed by the transcription factors OCT4, SOX2 and NANOG. Recent studies on reprogramming somatic cells to induced pluripotent stem cells highlight OCT4 as a key regulator of pluripotency. RESULTS: We have carried out an integrated analysis of high-throughput data (ChIP-on-chip and RNAi experiments along with promoter sequence analysis of putative target genes) and identified a core OCT4 regulatory network in human embryonic stem cells consisting of 33 target genes. Enrichment analysis with these target genes revealed that this integrative analysis increases the functional information content by factors of 1.3 - 4.7 compared to the individual studies. In order to identify potential regulatory co-factors of OCT4, we performed a de novo motif analysis. In addition to known validated OCT4 motifs we obtained binding sites similar to motifs recognized by further regulators of pluripotency and development; e.g. the heterodimer of the transcription factors C-MYC and MAX, a prerequisite for C-MYC transcriptional activity that leads to cell growth and proliferation. CONCLUSION: Our analysis shows how heterogeneous functional information can be integrated in order to reconstruct gene regulatory networks. As a test case we identified a core OCT4-regulated network that is important for the analysis of stem cell characteristics and cellular differentiation. Functional information is largely enriched using different experimental results. The de novo motif discovery identified well-known regulators closely connected to the OCT4 network as well as potential new regulators of pluripotency and differentiation. These results provide the basis for further targeted functional studies. This model is hosted on BioModels Database and identified by: MODEL1305010000 . To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models . To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

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