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  • PU.1 drives specification of pluripotent stem cell-derived endothelial cells to LSEC-like cells.

PU.1 drives specification of pluripotent stem cell-derived endothelial cells to LSEC-like cells.

Cell death & disease (2021-01-16)
Jonathan De Smedt, Elise Anne van Os, Irene Talon, Sreya Ghosh, Burak Toprakhisar, Rodrigo Furtado Madeiro Da Costa, Samantha Zaunz, Marta Aguirre Vazquez, Ruben Boon, Pieter Baatsen, Ayla Smout, Stefaan Verhulst, Leo A van Grunsven, Catherine M Verfaillie
ABSTRACT

To date, there is no representative in vitro model for liver sinusoidal endothelial cells (LSECs), as primary LSECs dedifferentiate very fast in culture and no combination of cytokines or growth factors can induce an LSEC fate in (pluripotent stem cell (PSC)-derived) endothelial cells (ECs). Furthermore, the transcriptional programmes driving an LSEC fate have not yet been described. Here, we first present a computational workflow (CenTFinder) that can identify transcription factors (TFs) that are crucial for modulating pathways involved in cell lineage specification. Using CenTFinder, we identified several novel LSEC-specific protein markers, such as FCN2 and FCN3, which were validated by analysis of previously published single-cell RNAseq data. We also identified PU.1 (encoded by the SPI1 gene) as a major regulator of LSEC-specific immune functions. We show that SPI1 overexpression (combined with the general EC TF ETV2) in human PSCs induces ECs with an LSEC-like phenotype. The ETV2-SPI1-ECs display increased expression of LSEC markers, such as CD32B and MRC1, as well as several of the proposed novel markers. More importantly, ETV2-SPI1-ECs acquire LSEC functions, including uptake of FSA-FITC, as well as labelled IgG. In conclusion, we present the CenTFinder computational tool to identify key regulatory TFs within specific pathways, in this work pathways of lineage specification, and we demonstrate its use by the identification and validation of PU.1 as a master regulator for LSEC fating.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Bovine Serum Albumin solution, 35% in DPBS, sterile-filtered, BioXtra, suitable for cell culture
Sigma-Aldrich
Propidium iodide, ≥94% (HPLC)
Sigma-Aldrich
GenElute Mammalian Total RNA Miniprep Kit, sufficient for 70 purifications