PAR1 Scaffolds TGFβRII to Downregulate TGF-β Signaling and Activate ESC Differentiation to Endothelial Cells.

Haixia Gong,Shejuan An,Jalees Rehman,Asrar B Malik,Menglin Liu,Wei Zhang,Victoria Mastej,Stefan Offermanns,Manish Mittal,Zhigang Hong,Antonia Sassmann

doi:10.1016/j.stemcr.2016.10.006

Abstract

SummaryWe studied the function of the G-protein-coupled receptor PAR1 in mediating the differentiation of mouse embryonic stem cells (mESCs) to endothelial cells (ECs) that are capable of inducing neovascularization. We observed that either deletion or activation of PAR1 suppressed mouse embryonic stem cell (mESC) differentiation to ECs and neovascularization in mice. This was mediated by induction of TGFβRII/TGFβRI interaction, forming an active complex, which in turn induced SMAD2 phosphorylation. Inhibition of TGF-β signaling in PAR1-deficient mESCs restored the EC differentiation potential of mESCs. Thus, PAR1 in its inactive unligated state functions as a scaffold for TGFβRII to downregulate TGF-β signaling, and thereby promote ESC transition to functional ECs. The PAR1 scaffold function in ESCs is an essential mechanism for dampening TGF-β signaling and regulating ESC differentiation.

Highlights

G-protein-coupled receptors (GPCRs), such as PAR1 (Protease Activated Receptor 1, referred to as CF2R, F2R, TR, and HTR), are transmembrane receptors that transmit extracellular signals into cells by coupling to specific heterotrimeric guanine nucleotide binding proteins (G proteins) and mediate an array of responses (Rosenbaum et al, 2009; Vassart and Costagliola, 2011)
PAR1 Expression in mouse embryonic stem cells (mESCs) Differentiating into endothelial cells (ECs) To identify the GPCRs regulating mESC differentiation to ECs, we first performed a GPCR screen made up of 534 GPCRs and related G proteins in mESCs and mESC-derived ECs
In the undifferentiated mESC state and 160 genes having greater than four copies in mESC-ECs (Figures 1A and S1)

Summary

Introduction

G-protein-coupled receptors (GPCRs), such as PAR1 (Protease Activated Receptor 1, referred to as CF2R, F2R, TR, and HTR), are transmembrane receptors that transmit extracellular signals into cells by coupling to specific heterotrimeric guanine nucleotide binding proteins (G proteins) and mediate an array of responses (Rosenbaum et al, 2009; Vassart and Costagliola, 2011). The function ascribed to GPCRs is the result of agonist binding to the receptor, resulting in activation of specific G proteins such as stimulatory Gas and inhibitory Gai subunits, which selectively activate or inactivate effector pathways to mediate the desired responses (Kobilka, 2007; Wess, 1997). Little is known about the role of GPCRs in mediating the differentiation of stem cells to terminally differentiated cells (Callihan et al, 2011; Kobayashi et al, 2010). The role of GPCR signaling in mediating the differentiation of pluripotent embryonic stem cells (ESCs) into differentiated cells has not been widely explored

Results

Discussion

Conclusion