Dual Functions of T-Box 3 (Tbx3) in the Control of Self-renewal and Extraembryonic Endoderm Differentiation in Mouse Embryonic Stem Cells

Rui Lu,Ying Jin,Acong Yang

doi:10.1074/jbc.m110.202150

Abstract

Embryonic stem cells (ESCs) possess the capacity to proliferate indefinitely in an undifferentiated state and to differentiate into various cell types in an organism. However, the critical question of how self-renewal and differentiation are precisely regulated in ESCs is not entirely understood at present. Here, we report the essential role of Tbx3, a pluripotency-related transcription factor of the T-box gene family, for both the maintenance of self-renewal of mouse ESCs and for their differentiation into extraembryonic endoderm (ExEn). We show that Tbx3 is highly expressed in ExEn cells in addition to undifferentiated ESCs. Knockdown of Tbx3 expression using tetracycline-regulated Tbx3 siRNA resulted in the attenuation of ESC self-renewal ability and aberrant differentiation processes, including reduced ExEn differentiation but enhanced ectoderm and trophectoderm differentiation. Conversely, inducible forced expression of Tbx3 triggered ExEn lineage commitment. Mechanistically, Tbx3 directly activated the expression of Gata6, an essential regulator of ExEn. Interestingly, Tbx3 modulated H3K27me3 modification and the association of the PRC2 complex with the promoter region of Gata6. Taken together, the results of this study revealed a previously unappreciated role of a pluripotency factor in ExEn differentiation. Additionally, our data reveal that Tbx3 may function through direct binding and epigenetic modification of histones on the Gata6 promoter to maintain the ExEn differentiation potential of ESCs.

Highlights

Grants 30730051, 30700116, 30911130361, and 91019929, National High Technology Research and Development Program of China Grants 2009CB941103, 2007CB947904, 2007CB948004, and 2010CB945200, and Shanghai Science and Technology Developmental Foundations Grant 08dj1400502
Tel./Fax: 86-21-63852591; E-mail: yjin@sibs. ac.cn. 2 The abbreviations used are: ExEn, extraembryonic endoderm; embryonic stem cells (ESCs), embryonic stem cell; LIF, leukemia inhibitory factor; polycomb repressive complex 2 (PRC2), polycomb repressive mately contributes to the yolk sac, whereas the epiblast contains pluripotent cells that generate all of the cell types of the three embryonic germ layers and some extraembryonic tissues [1, 2]
Because the expression of Tbx3 in other cell types has not been carefully examined, we compared the level of Tbx3 mRNA and proteins in various cell lines, including mouse ESCs (CGR8 and E14T), mouse fibroblast cells (mouse embryonic fibroblasts (MEF) and NIH 3T3), ExEn cells (XEN), and trophoblast stem (TS) cells [26, 27] and found that the Tbx3 expression level was highest in ESC lines and lowest in MEF, NIH3T3, and TS cells, similar to that of Oct4 and Nanog

Summary

Introduction

Grants 30730051, 30700116, 30911130361, and 91019929, National High Technology Research and Development Program of China Grants 2009CB941103, 2007CB947904, 2007CB948004, and 2010CB945200, and Shanghai Science and Technology Developmental Foundations Grant 08dj1400502. Our data reveal a novel function of Tbx3 in sustaining the potential of pluripotent cells to differentiate into ExEn in addition to its known role in maintaining ESC self-renewal and provide new insights into epigenetic regulation of ESC properties.

Results

Conclusion