Project description:Production of cultured meat requires defined medium formulations for the robust differentiation of myogenic cells into mature skeletal muscle fibres in vitro. Whilst such formulations can drive myogenic differentiation to an extent similar to serum-starvation based protocols, these cultures are visually heterogeneous in nature, with a significant proportion of cells not participating in myofusion, limiting the maturation of the muscle. Here, we use RNA sequencing to characterise this heterogeneity at single-nucleus resolution, identifying distinct cellular subpopulations, including proliferative cells that fail to exit the cell cycle, and 'reserve cells' that do not commit to myogenic differentiation. By targeting the ERK, RXR and NOTCH pathways, we show that cell cycle exit can be promoted whilst simultaneously abrogating reserve cell formation. Under these improved culture conditions, fusion indices close to 100% can be robustly obtained in 2D culture. We further show that this translates to higher levels of myotube formation and muscle protein accumulation in animal-free bioartificial muscle (BAM) constructs, providing proof of principle for the generation of highly differentiated cultured muscle with excellent mimicry to traditional meat.
Project description:DNA damage activates diverse cellular responses – either protective or deleterious –that ultimately promote or inhibit proliferation. How the distinct responses conferring crucial cell fate decisions are chosen is unclear. Using a systems approach, we demonstrate that the dynamic features of Atm dependent DNA double-strand break (DSB) signalling response dictate cellular outcome. Combining temporal phosphoproteome and nascent transcriptome analyses after low or high DNA-damage-load, we discovered that some responses, such as Tp53 activation, have an activation threshold and others arise independently of DNA-damage-load. Using DSB repair deficient cells, we show that persistent DSBs alter the kinetics – but not the amplitude – of Atm signalling. Thus, we demonstrate that pathway choices are dictated by the signalling dynamics and hence cell fate decisions are responsive to DNA-damage-load and repair capacity of the cells.
Project description:Notch signaling regulates several cellular processes including cell fate decisions and proliferation in both invertebrates and mice. However, comparatively less is known about the role of Notch during early human development. Here, we examined the function of Notch signaling during hematopoietic lineage specification from human pluripotent stem cells (hPSCs) of both embryonic and adult fibroblast origin. Using immobilized Notch ligands and siRNA to Notch receptors we have demonstrated that Notch1, but not Notch2 activation, induced HES1 expression and generation of committed hematopoietic progenitors. Using gain and loss of function approaches, this was shown to be attributed to Notch signaling regulation through HES1, that dictated cell fate decisions from bipotent precursors either to the endothelial or hematopoietic lineages at the clonal level. Our study reveals a previously unappreciated role for the Notch pathway during early human hematopoiesis, whereby Notch signaling via HES1 represents a toggle switch of hematopoietic vs. endothelial fate specification. Human pluripotent stem cells (hPSCs) have differentiation potential into three embryonic germ layers including blood. Notch signaling is one of important signaling pathways involved in blood differentiation of hPSCs. Thus, in order to examine the effect of Notch signaling pathways during hematopoietic differentiation of hPSCs, embryoid bodies (EBs) were formed and cultured for 10 days in the combination of cytokines and growth factors (Chadwick, Blood, 2003; 300 ng/ml of SCF, 300 ng/ml of Flt-3L, 10 ng/ml of IL-3, 10 ng/ml of IL-6, and 50 ng/ml of G-CSF) to induce differentiation into blood. Additionally, CD31+CD45- bipotent hemogenic precursors were isolated from day10 hematopoietic EBs (Wang et al., Immunity, 2004)
Project description:The canonical function of the Hippo signaling pathway is the regulation of organ growth. How this pathway controls cell fate determination is less well understood. Here, we identify a function of the Hippo pathway in cell fate decisions in the developing Drosophila eye, exerted through the interaction of Yorkie (Yki) with the transcriptional regulator Bonus (Bon), an ortholog of mammalian Transcriptional Intermediary Factor 1/tripartite motif (TIF1/TRIM) family proteins. Instead of controlling tissue growth, Yki and Bon promote epidermal and antennal fates at the expense of the eye fate. Proteomic, transcriptomic, and genetic analyses reveal that Yki and Bon control these cell fate decisions by recruiting transcriptional and post-transcriptional co-regulators, and by repressing Notch target genes and activating epidermal differentiation genes. Our work expands the range of functions and regulatory mechanisms under Hippo pathway control.
Project description:The role of nutrient signaling processes in the fate decision of CD8 is incompletely understood. By performing in vivo pooled CRISPR-Cas9 screening, we uncovered nutrient signaling processes underpinning the dynamics and heterogeneity of CD8 T cell fate decisions.
Project description:The role of nutrient signaling processes in the fate decision of CD8 is incompletely understood. By performing in vivo pooled CRISPR-Cas9 screening, we uncovered nutrient signaling processes underpinning the dynamics and heterogeneity of CD8 T cell fate decisions.
Project description:The role of nutrient signaling processes in the fate decision of CD8 is incompletely understood. By performing in vivo pooled CRISPR-Cas9 screening, we uncovered nutrient signaling processes underpinning the dynamics and heterogeneity of CD8 T cell fate decisions.