Despite the importance of inter-cellular communication networks in regulating stem cell fate decisions, very little is known about the topology, dynamics, or functional significance. Using human blood stem cell cultures as an experimental paradigm, we present a novel bioinformatic approach to integrate genome-scale molecular profiles (transcriptome and secretome) and publicly available databases to reconstruct soluble factor-mediated inter-cellular signalling networks regulating blood stem cell fate decisions.
Dynamic interaction networks in a hierarchically organized tissue.
Specimen part
View SamplesPluripotent stem cells (PSCs) exist in multiple stable states, each with specific cellular properties and molecular signatures. The process by which pluripotency is either maintained or destabilized to initiate specific developmental programs is poorly understood. We have developed a model to predict stabilized PSC gene regulatory network (GRN) states in response to combinations of input signals. While previous attempts to model PSC fate have been limited to static cell compositions, our approach enables simulations of dynamic heterogeneity by combining an Asynchronous Boolean Simulation (ABS) strategy with simulated single cell fate transitions using a Strongly Connected Components (SCCs). This computational framework was applied to a reverse-engineered and curated core GRN for mouse embryonic stem cells (mESCs) to simulate responses to LIF, Wnt/ß-catenin, FGF/ERK, BMP4, and Activin A/Nodal pathway activation. For these input signals, our simulations exhibit strong predictive power for gene expression patterns, cell population composition, and nodes controlling cell fate transitions. The model predictions extend into early PSC differentiation, demonstrating, for example, that a Cdx2-high/Oct4-low state can be efficiently generated from mESCs residing in a naïve and signal-receptive state sustained by combinations of signaling activators and inhibitors. Overall design: Examination of perturbed PSCs versus control PSCs and mesoderm progenitors Mouse pluripotent stem cells were grown on tissue culture plates for two days in serum-containing, feeder free medium supplemented with the following cytokines/small molecules: 2i = CHIR99021 (Reagents Direct 27-H76 – 3µM) & PD0325901 (Reagents Direct 39-C68 – 1µM) Jaki = JAK inhibitor (EMD Millipore 420097 – 2.0µM) BMP = BMP4 (R&D Systems 314-BP-010 – 10ng/ml) Alk5i = ALK5 inhibitor II (Cedarlane ALX-270-445 - 10µM)
Modeling signaling-dependent pluripotency with Boolean logic to predict cell fate transitions.
Cell line, Treatment, Subject, Time
View SamplesThe neural stem cell decision to self-renew or differentiate is tightly regulated by its microenvironment. Here, we have asked about this microenvironment, focusing on growth factors in the embryonic cortex at a time when it is largely comprised of neural precursor cells (NPCs) and newborn neurons. We show that cortical NPCs secrete factors that promote their maintenance while cortical neurons secrete factors that promote differentiation. To define factors important for these activities, we used transcriptome profiling to identify ligands produced by NPCs and neurons, cell surface mass spectrometry to identify receptors on these cells, and computational modeling to integrate these data. The resultant model predicts a complex growth factor environment with multiple autocrine and paracrine interactions. We tested this communication model, focusing on neurogenesis, and identified IFN, Nrtn and glial-derived neurotrophic factor (GDNF) as ligands with unexpected roles in promoting neurogenic differentiation of NPCs in vivo.
Proneurogenic Ligands Defined by Modeling Developing Cortex Growth Factor Communication Networks.
Specimen part
View SamplesSamples of adherent and suspension cells undergoing reprogramming were collected at day 0, day2, day6, day15 (with doxycycline) and day25 (without doxycycline).
Derivation, expansion and differentiation of induced pluripotent stem cells in continuous suspension cultures.
Specimen part
View SamplesComplex tissues contain multiple cell types that are hierarchically organized within morphologically and functionally distinct compartments. Construction of engineered tissues with optimized tissue architecture has been limited by tissue fabrication techniques, which do not enable versatile microscale organization of multiple cell types in tissues of size adequate for physiologic studies and tissue therapies. Here, we present an Intaglio-Void/Embed-Relief Topographic (InVERT) molding method for microscale organization of many cell types, including induced pluripotent stem cell (iPS)-derived progeny, within a variety of synthetic and natural extracellular matrices and across tissues of sizes appropriate for in vitro, pre-clinical, and clinical biologic studies. We demonstrate that compartmental placement of non-parenchymal cells relative to primary or iPS-derived hepatocytes and hepatic compartment microstructure and cellular composition modulate hepatic functions. Configurations found to be optimal in vitro also result in superior survival and function after transplantation into mice, demonstrating the importance of architectural optimization prior to implantation.
InVERT molding for scalable control of tissue microarchitecture.
Specimen part
View SamplesStem cell fate is governed by the integration of intrinsic and extrinsic positive and negative signals upon inherent transcriptional networks. To identify novel embryonic stem cell (ESC) regulators and assemble transcriptional networks controlling ESC fate, we performed temporal expression microarray analyses of ESCs following the initiation of commitment and integrated these data with known genome-wide transcription factor binding. Effects of forced under- or over-expression of predicted novel regulators, defined as differentially expressed genes with potential binding sites for known regulators of pluripotency, demonstrated greater than 90% correspondence with predicted function, as assessed by functional and high content assays of self-renewal. We next assembled 43 theoretical transcriptional networks in ESCs, 82% (23 out of 28 tested) of which were supported by analysis of genome-wide expression in Oct4 knockdown cells. By using this integrative approach we have, for the first time, formulated novel networks describing gene repression of key developmental regulators in undifferentiated ESCs and successfully predicted the outcomes of genetic manipulation of these networks.
Prediction and testing of novel transcriptional networks regulating embryonic stem cell self-renewal and commitment.
No sample metadata fields
View SamplesThe hair follicle (HF) is a complex miniorgan that serves as an ideal model system to study stem cell (SC) interactions with the niche during growth and regeneration. Dermal papilla (DP) cells are required for activating SCs during the adult hair cycle, but the signal exchange between niche and SC precursors/transit amplifying progenitor cells (TACs) that regulates HF morphogenetic growth is largely unknown. Here we use six transgenic reporters to isolate 14 major skin and HF cell populations. With next-generation RNA sequencing we characterize their transcriptomes and define unique molecular signatures. SC precursors, TACs and the DP niche express a plethora of known and novel ligands and receptors. Signaling interaction network analysis reveals a birds-eye view of pathways implicated in epithelial-mesenchymal interactions. Using a systematic tissue-wide approach this work provides a comprehensive platform, linked to an interactive online database, to identify and further explore the SC/TAC/niche crosstalk regulating HF growth. Overall design: FACS was used to isolate specific cell types from P5 mouse back skin
Signaling Networks among Stem Cell Precursors, Transit-Amplifying Progenitors, and their Niche in Developing Hair Follicles.
Specimen part, Subject
View SamplesHsa-mir-365-2 is one of the two precursors that give rise to miR-365. We discovered that miR-365 directly regulates a lung cancer and developmental gene termed thyroid transcription factor 1 (TTF-1 or NKX2-1).
MiR-365 regulates lung cancer and developmental gene thyroid transcription factor 1.
Cell line
View SamplesAlternative splicing (AS) is a key process underlying the expansion of proteomic diversity and the regulation of gene expression. However, the contribution of AS to the control of embryonic stem cell (ESC) pluripotency is not well understood. Here, we identify an evolutionarily conserved ESC-specific AS event that changes the DNA binding preference of the forkhead family transcription factor FOXP1. We show that the ESC-specific isoform of FOXP1 stimulates the expression of transcription factor genes required for pluripotency including OCT4, NANOG, NR5A2 and GDF3, while concomitantly repressing genes required for ESC differentiation. Remarkably, this isoform also promotes the maintenance of ESC pluripotency and the efficient reprogramming of somatic cells to induced pluripotent stem cells. These results thus reveal that an AS switch plays a pivotal role in the regulation of pluripotency and functions by controlling critical ESC-specific transcriptional programs. Overall design: Exons 18 and 18b form a mutually exclusive splicing event. The FOXP1 (non-ES) isoform contains only exon 18 and not 18b, while the FOXP1-ES isoform contains only exon 18b and not 18. To investigate whether FOXP1 and FOXP1-ES control different sets of genes, we performed knockdowns using custom siRNA pools targeting FOXP1 exons 18 or 18b in undifferentiated H9 cells, followed by RNA-Seq profiling.
An alternative splicing switch regulates embryonic stem cell pluripotency and reprogramming.
Specimen part, Subject
View SamplesComparative analyses of Mex67 and Npl3 binding to mRNA at normal growth condition (25째C) and upon shift to heat stress (30 min, 42째C). Overall design: Examination of two biological RNA Co-IP replicates of Mex67, Npl3 and no tag control at 25째C and upon shift to 30 min at 42째C (Heat stress) and subsequent Illumina RNA deep-sequencing
mRNA quality control is bypassed for immediate export of stress-responsive transcripts.
Cell line, Subject
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