Shuang Zhao, Yuebing Wang, Yan Nie, Na Liu, Zongjin Li, Dan Wang, Kaiyue Zhang, Yang Xu, Hui Sang, Yan Zhang, Ningning He, and Xiaoyan Xie
// Dan Wang 1, 3, * , Hui Sang 1, 3, * , Kaiyue Zhang 2 , Yan Nie 2 , Shuang Zhao 1, 3 , Yan Zhang 2, 3 , Ningning He 2 , Yuebing Wang 2 , Yang Xu 2 , Xiaoyan Xie 4 , Zongjin Li 1, 2 , Na Liu 1, 2 1 Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China 2 School of Medicine, Nankai University, Tianjin, China 3 College of Life Sciences, Nankai University, Tianjin, China 4 Stem Cells and Regenerative Medicine Lab, Beijing Institute of Transfusion Medicine, Beijing, China * These authors contributed equally to this work Correspondence to: Na Liu, email: liuna@nankai.edu.cn Zongjin Li, email: zongjinli@nankai.edu.cn Keywords: embryonic stem cell, ground state, Stat3 signal pathway, imaging Received: November 24, 2016 Accepted: March 01, 2017 Published: March 10, 2017 ABSTRACT Embryonic stem cells (ES cells) can be maintained its undifferentiated state with feeder cells or LIF, which can activate Jak/Stat3 pathway. Recently, it has been reported a new culture condition comprising serum-free medium with ERK and GSK3β inhibitors (2i) could drive ES cells into a state of pluripotency more like inner cell mass (ICM) in mouse blastocysts called ground state. However, although 2i could sustain ES cells self-renewal, LIF is routinely added. The roles of Stat3 activation are still unclear now. Here we investigated whether Jak/Stat3 might also contribute to the induction of ground state pluripotency. We introduced a lentiviral construct with 7-repeat Stat3-binding sequence to drive Renilla luciferase into ES cells, which can be used as a reporter to detect Stat3 activation by noninvasive bioluminescence imaging. Using this ES cells, we investigated the role of Stat3 activation in ground state maintenance. The results showed that Stat3 could be activated by 2i. Stattic, a chemical inhibitor of Stat3 phosphorylation, could effectively inhibit Stat3 activation in ES cells. When Stat3 activation was suppressed, ground state related genes were down regulated, and ES cells could not be maintained the ground state pluripotency even in 2i medium. All of these results indicate Stat3 activation is required in ground state maintenance.