Prohibitin 2 Regulates the Proliferation and Lineage-Specific Differentiation of Mouse Embryonic Stem Cells in Mitochondria

Megumi Kowno,Shinji Komazaki,Yuko Kokubu,Kanako Watanabe-Susaki,Hisako Ishimine,Akira Kurisaki,Yohei Ishigaki,Yasuhiro Seki,Keigoh Ohnishi,Kaoru Kato,Atsushi Intoh,Naoto Ninomiya,Hitomi Takada,Makoto Asashima,Kei Enomoto,Noriko Yamakawa ,Taka Aki K Noguchi ,Yuichi Nakajima ,Xiaocong Wang ,Pi Chao Wang

doi:10.1371/journal.pone.0081552

Abstract

BackgroundThe pluripotent state of embryonic stem (ES) cells is controlled by a network of specific transcription factors. Recent studies also suggested the significant contribution of mitochondria on the regulation of pluripotent stem cells. However, the molecules involved in these regulations are still unknown.Methodology/Principal FindingsIn this study, we found that prohibitin 2 (PHB2), a pleiotrophic factor mainly localized in mitochondria, is a crucial regulatory factor for the homeostasis and differentiation of ES cells. PHB2 was highly expressed in undifferentiated mouse ES cells, and the expression was decreased during the differentiation of ES cells. Knockdown of PHB2 induced significant apoptosis in pluripotent ES cells, whereas enhanced expression of PHB2 contributed to the proliferation of ES cells. However, enhanced expression of PHB2 strongly inhibited ES cell differentiation into neuronal and endodermal cells. Interestingly, only PHB2 with intact mitochondrial targeting signal showed these specific effects on ES cells. Moreover, overexpression of PHB2 enhanced the processing of a dynamin-like GTPase (OPA1) that regulates mitochondrial fusion and cristae remodeling, which could induce partial dysfunction of mitochondria.Conclusions/SignificanceOur results suggest that PHB2 is a crucial mitochondrial regulator for homeostasis and lineage-specific differentiation of ES cells.

Highlights

The pluripotent stem cells, such as embryonic stem (ES) cells and induced pluripotent stem cells, are regulated by a specific transcription network composed of core transcription factors such as Oct4, Sox2, and Nanog [1,2]
We have shown that prohibitin 2 (PHB2) localized in mitochondria is essential for the survival and proliferation of pluripotent ES cells
We observed prolonged alkaline phosphatase activity in PHB2-expressing ES cells cultured in the absence of leukemia inhibitory factor (LIF), overexpression of PHB2 was not able to maintain the pluripotent state of ES cells in a long-term culture without LIF

Summary

Introduction

The pluripotent stem cells, such as embryonic stem (ES) cells and induced pluripotent stem (iPS) cells, are regulated by a specific transcription network composed of core transcription factors such as Oct, Sox, and Nanog [1,2]. Recent reports suggested the involvement of other factors, such as mitochondrial functions, in the regulation of stem cells [3,4]. PHB2 is mainly involved in the functionality of the mitochondrial inner membrane as a proteinlipid scaffold. Some reports suggested other functions of PHB2, such as transcriptional regulation in the nucleus and cell signaling in the plasma membrane [9]. The pluripotent state of embryonic stem (ES) cells is controlled by a network of specific transcription factors. Recent studies suggested the significant contribution of mitochondria on the regulation of pluripotent stem cells. The molecules involved in these regulations are still unknown

Methods

Results

Conclusion