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Gassaloglu, S. I.

Publications and source records attributed to Gassaloglu, S. I..

2 recordsLinked to original sources

Integrated Molecular-Phenotypic Profiling Reveals Metabolic Control of Morphological Variation in Stembryos

Mammalian stem-cell-based models of embryo development (stembryos) hold great promise in basic and applied research. However, considerable phenotypic variation despite identical culture conditions limits their potential. The biological processes underlying this seemingly stochastic variation are poorly understood. Here, we investigate the roots of this phenotypic variation by intersecting transcriptomic states and morphological history of individual stembryos across stages modeling post-implantation and early organogenesis. Through machine learning and integration of time-resolved single-cell RNA-sequencing with imaging-based quantitative phenotypic profiling, we identify early features predictive of the phenotypic end-state. Leveraging this predictive power revealed that early imbalance of oxidative phosphorylation and glycolysis results in aberrant morphology and a neural lineage bias that can be corrected by metabolic interventions. Collectively, our work establishes divergent metabolic states as drivers of phenotypic variation, and offers a broadly applicable framework to chart and predict phenotypic variation in organoid systems. The strategy can be leveraged to identify and control underlying biological processes, ultimately increasing the reproducibility of in vitro systems. HighlightsO_LITime-resolved single-cell RNA-sequencing and imaging-based quantitative charting of hundreds of individual stembryos generates molecular and phenotypic fingerprints C_LIO_LIMachine learning and integration of molecular and phenotypic fingerprints identifies features and biological processes predictive of phenotypic end-state C_LIO_LIEarly imbalance of oxidative phosphorylation and glycolysis results in aberrant morphology and cellular composition C_LIO_LIMetabolic interventions tune stembryo end-state and can correct derailment of differentiation outcomes C_LI

developmental biology↗

Hypoxia induces a transcriptional early primitive streak signature in pluripotent cells enhancing spontaneous elongation and lineage representation in gastruloids

The cellular microenvironment together with intrinsic regulators shapes stem cell identity and differentiation capacity. Mammalian early embryos are exposed to hypoxia in vivo and appear to benefit from hypoxic culture in vitro. Yet, components of the hypoxia response and how their interplay impacts stem cell transcriptional networks and lineage choices remain poorly understood. Here we investigated the molecular effects of acute and prolonged hypoxia on distinct embryonic and extraembryonic stem cell types as well as the functional impact on differentiation potential. We find a temporal and cell type-specific transcriptional response including an early primitive streak signature in hypoxic embryonic stem (ES) cells. Using a 3D gastruloid differentiation model, we show that hypoxia-induced T expression enables symmetry breaking and axial elongation in the absence of exogenous WNT activation. Importantly, hypoxia also modulates T levels in conventional gastruloids and enhances representation of endodermal and neural markers. Mechanistically, we identify Hif1 as a central factor that mediates the transcriptional response to hypoxia in balance with epigenetic and metabolic rewiring. Our findings directly link the microenvironment to stem cell function and provide a rationale supportive of applying physiological conditions in models of embryo development

developmental biology↗