scholarly journals Morphogen dynamics control patterning in a stem cell model of the human embryo

2017 ◽  
Author(s):  
Idse Heemskerk ◽  
Kari Burt ◽  
Matthew Miller ◽  
Sapna Chhabra ◽  
M. Cecilia Guerra ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cell Differentiation ◽  
Cell Fate ◽  
Human Embryo ◽  
Cell Model ◽  
Stem Cell Differentiation ◽  
Concentration Increase ◽  
Cell Fates ◽  
Cell Fate Decisions ◽  
Stem Cell Model

During embryonic development, diffusible signaling molecules called morphogens are thought to determine cell fates in a concentration-dependent manner1–4, and protocols for directed stem cell differentiation are based on this picture5–8. However, in the mammalian embryo, morphogen concentrations change rapidly compared to the time for making cell fate decisions9–12. It is unknown how changing ligand levels are interpreted, and whether the precise timecourse of ligand exposure plays a role in cell fate decisions. Nodal and BMP4 are morphogens crucial for gastrulation in vertebrates13. Each pathway has distinct receptor complexes that phosphorylate specific signal transducers, known as receptor-Smads, which then complex with the shared cofactor Smad4 to activate target genes14. Here we show in human embryonic stem cells (hESCs) that the response to BMP4 signaling indeed is determined by the ligand concentration, but that unexpectedly, the expression of many mesodermal targets of Activin/Nodal depends on rate of concentration increase. In addition, we use live imaging of hESCs with GFP integrated at the endogenous SMAD4 locus to show that a stem cell model for the human embryo15 generates a wave of Nodal signaling. Cells experience rapidly increasing Nodal specifically in the region of mesendoderm differentiation. We also demonstrate that pulsatile stimulation with Activin induces repeated strong signaling and enhances mesoderm differentiation. Our results break with the paradigm of concentration-dependent differentiation and demonstrate an important role for morphogen dynamics in the cell fate decisions associated with mammalian gastrulation. They suggest a highly dynamic picture of embryonic patterning where some cell fates depend on rapid concentration increase rather than absolute levels, and point to ligand dynamics as a new dimension to optimize protocols for directed stem cell differentiation.

scholarly journals Ultra-multiplexed analysis of single-cell dynamics reveals logic rules in differentiation

2019 ◽  
Vol 5 (4) ◽  
pp. eaav7959 ◽  
Author(s):  
Ce Zhang ◽  
Hsiung-Lin Tu ◽  
Gengjie Jia ◽  
Tanzila Mukhtar ◽  
Verdon Taylor ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cell Differentiation ◽  
Single Cell ◽  
Cell Fate ◽  
Single Cell Analysis ◽  
Single Cells ◽  
Critical Role ◽  
Stem Cell Differentiation ◽  
Cell Fate Decisions ◽  
Cellular Microenvironments

Dynamical control of cellular microenvironments is highly desirable to study complex processes such as stem cell differentiation and immune signaling. We present an ultra-multiplexed microfluidic system for high-throughput single-cell analysis in precisely defined dynamic signaling environments. Our system delivers combinatorial and time-varying signals to 1500 independently programmable culture chambers in week-long live-cell experiments by performing nearly 106 pipetting steps, where single cells, two-dimensional (2D) populations, or 3D neurospheres are chemically stimulated and tracked. Using our system and statistical analysis, we investigated the signaling landscape of neural stem cell differentiation and discovered “cellular logic rules” that revealed the critical role of signal timing and sequence in cell fate decisions. We find synergistic and antagonistic signal interactions and show that differentiation pathways are highly redundant. Our system allows dissection of hidden aspects of cellular dynamics and enables accelerated biological discovery.

scholarly journals Context-dependent roles of YAP/TAZ in stem cell fates and cancer

2021 ◽  
Author(s):  
Lucy LeBlanc ◽  
Nereida Ramirez ◽  
Jonghwan Kim
Keyword(s):  
Stem Cell ◽  
Cell Fate ◽  
Control Cell ◽  
Substantial Portion ◽  
Cell Fates ◽  
Cell Fate Decisions ◽  
Cell Death Pathways ◽  
Multiple Context ◽  
Cancer Cell Survival ◽  
Context Dependent

AbstractHippo effectors YAP and TAZ control cell fate and survival through various mechanisms, including transcriptional regulation of key genes. However, much of this research has been marked by conflicting results, as well as controversy over whether YAP and TAZ are redundant. A substantial portion of the discordance stems from their contradictory roles in stem cell self-renewal vs. differentiation and cancer cell survival vs. apoptosis. In this review, we present an overview of the multiple context-dependent functions of YAP and TAZ in regulating cell fate decisions in stem cells and organoids, as well as their mechanisms of controlling programmed cell death pathways in cancer.

scholarly journals Polyamine-controlled proliferation and protein biosynthesis are independent determinants of hair follicle stem cell fate

2020 ◽  
Author(s):  
Kira Allmeroth ◽  
Christine S. Kim ◽  
Andrea Annibal ◽  
Andromachi Pouikli ◽  
Carlos Andrés Chacón-Martínez ◽  
...  
Keyword(s):  
Stem Cell ◽  
Hair Follicle ◽  
Cell Fate ◽  
Protein Biosynthesis ◽  
Mrna Translation ◽  
Stem Cell Differentiation ◽  
List Type ◽  
Stem Cell Fate ◽  
Cell Fate Decisions ◽  
Hair Follicle Stem Cell

AbstractStem cell differentiation is accompanied by an increase in mRNA translation. The rate of protein biosynthesis is influenced by the polyamines putrescine, spermidine, and spermine that are essential for cell growth and stem cell maintenance. However, the role of polyamines as endogenous effectors of stem cell fate and whether they act through translational control remains obscure. Here, we investigated the function of polyamines in stem cell fate decisions using hair follicle stem cell (HFSC) organoids. HFSCs showed lower translation rates than progenitor cells, and a forced suppression of translation by direct targeting of the ribosome or through specific depletion of natural polyamines elevated stemness. In addition, we identified N1-acetylspermidine as a novel parallel regulator of cell fate decisions, increasing proliferation without reducing translation. Overall, this study delineates the diverse routes of polyamine metabolism-mediated regulation of stem cell fate decisions.Key PointsLow mRNA translation rates characterize hair follicle stem cell (HFSC) stateDepletion of natural polyamines enriches HFSCs via reduced translationN1-acetylspermidine promotes HFSC state without reducing translationN1-acetylspermidine expands the stem cell pool through elevated proliferation

scholarly journals Mitochondria define intestinal stem cell differentiation downstream of a FOXO/Notch axis

2019 ◽  
Author(s):  
M.C. Ludikhuize ◽  
M. Meerlo ◽  
M. Pages Gallego ◽  
M. Burgaya Julià ◽  
N.T.B. Nguyen ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cell Differentiation ◽  
Cell Fate ◽  
Cell Function ◽  
Mitochondrial Fission ◽  
Stem Cell Differentiation ◽  
Notch Signalling ◽  
Intestinal Stem Cell ◽  
Mitochondrial Activity ◽  
Foxo Transcription Factors

SummaryDifferential signalling of the WNT and Notch pathways regulates proliferation and differentiation of Lgr5+ crypt-based columnar cells (CBCs) into all cell lineages of the intestine. We have recently shown that high mitochondrial activity in CBCs is key in maintaining stem cell function. Interestingly, while high mitochondrial activity drives CBCs, it is reduced in the adjacent secretory Paneth cells (PCs). This observation implies that during differentiation towards PCs, CBCs undergo a metabolic rewiring involving downregulation of mitochondrial number and activity, through a hitherto unknown mechanism. Here we demonstrate, using intestinal organoids that FoxO transcription factors and Notch signalling functionally interact in determining CBC cell fate. In agreement with the organoid data, combined Foxo1 and 3 deletion in mice increases PC number in the intestine. Importantly, we show that FOXO and Notch signalling converge onto regulation of mitochondrial fission, which in turn provokes stem cell differentiation into the secretory types; Goblet cells and PCs. Finally, mapping intestinal stem cell differentiation based on pseudotime computation of scRNA-seq data further supports the role of FOXO, Notch and mitochondria in determining secretory differentiation. This shows that mitochondria is not only a discriminatory hallmark of CBCs and PCs, but that its status actively determines lineage commitment during differentiation. Together, our work describes a new signalling-metabolic axis in stem cell differentiation and highlights the importance of mitochondria in determining cell fate.

scholarly journals An in vitro stem cell model of human epiblast and yolk sac interaction

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Kirsty ML Mackinlay ◽  
Bailey AT Weatherbee ◽  
Viviane Souza Rosa ◽  
Charlotte E Handford ◽  
George Hudson ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Fate ◽  
Human Embryo ◽  
Cell Model ◽  
Embryonic Stem ◽  
Yolk Sac ◽  
Embryonic Cells ◽  
Post Implantation

Human embryogenesis entails complex signalling interactions between embryonic and extra-embryonic cells. However, how extra-embryonic cells direct morphogenesis within the human embryo remains largely unknown due to a lack of relevant stem cell models. Here, we have established conditions to differentiate human pluripotent stem cells (hPSCs) into yolk sac-like cells (YSLCs) that resemble the post-implantation human hypoblast molecularly and functionally. YSLCs induce the expression of pluripotency and anterior ectoderm markers in human embryonic stem cells (hESCs) at the expense of mesoderm and endoderm markers. This activity is mediated by the release of BMP and WNT signalling pathway inhibitors, and, therefore, resembles the functioning of the anterior visceral endoderm signalling centre of the mouse embryo, which establishes the anterior-posterior axis. Our results implicate the yolk sac in epiblast cell fate specification in the human embryo and propose YSLCs as a tool for studying post-implantation human embryo development in vitro.

scholarly journals PASsing on Signals: PAS Kinase (PASK)-mTOR Signaling Conveys Nutrient Sufficiency Signals to Epigenetic (COMPASS) Complexes to Activate Stem Cell Differentiation Program (P15-009-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Chintan Kikani ◽  
Michael Xiao ◽  
Xiaoying Wu ◽  
Jared Rutter
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Differentiation ◽  
Cell Fate ◽  
Early Stage ◽  
Stem Cell Differentiation ◽  
Mtor Signaling ◽  
Kinase Assay ◽  
Cell Functions ◽  
Nutrient Signaling

Abstract Objectives To determine how nutrient signaling impacts stem cell functions Methods PASK phosphorylation: We measured in situ phosphorylation of PASK by metabolic 32P labeling of stem cells expressing WT or mutant versions of PASK. PASK Activation: PASK activation was measured using in vitro kinase assay using radio-labeled ATP. Myogenesis: Myogenesis was measured by immunohistological, and immunofluorescent analysis of differentiating muscle stem cells. Antibodies used were: Myogenin (F5D-Developmental Hybridoma), MF20 (Myosin heavy chain), Pax7 and MyoD. Results Stem cell fate in the tissue niche is intimately connected with intracellular metabolic state and the extracellular hormonal stimulations. We have identified PAS domain containing Kinase (PASK) as a stem cell enriched protein kinase that is required for establishment of the differentiation program in many stem cell paradigms. For this function, PASK phosphorylates Wdr5, a member of the COMPASS family of histone methyltransferases, to activate the epigenetic processes required for the stem cell differentiation (eLife, 2016). Here we show that a master nutrient sensor, mTOR complex 1 (mTORC1) activates PASK via multi-site phosphorylation during stem cell differentiation. This phosphorylation of PASK by mTORC1 is required for epigenetic activation of the Myogenin transcription, exit from the self-renewal and induction of the myogenesis program. Our data suggest that mTORC1-PASK signaling generates MyoG + committed myoblasts (epigenetically - an early stage of myogenesis), whereas mTORC1-S6K1 signaling is required for myoblast fusion (translationally - later stage of myogenesis). Conclusions Our discoveries show that nutrient signaling can partition stem cell fates during different stages of the myogenesis program downstream of mTOR signaling via activation of two distinct protein kinases. Funding Sources NIH R01 (Chintan Kikani), HHMI (Jared Rutter) Supporting Tables, Images and/or Graphs

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