Lysine-specific histone demethylase 1 inhibition promotes reprogramming by facilitating the expression of exogenous transcriptional factors and metabolic switch.

Hao Sun,Duanqing Pei,Chengqian Feng,Yunqian Guo,Yixin Zhang,Hui Zheng,Lingyu Li,Yuan Li,Lining Liang,Songwei He

doi:10.1038/srep30903

Abstract

Lysine-specific histone demethylase 1 (LSD1) regulates histone methylation and influences the epigenetic state of cells during the generation of induced pluripotent stem cells (iPSCs). Here we reported that LSD1 inhibition via shRNA or specific inhibitor, tranylcypromine, promoted reprogramming at early stage via two mechanisms. At early stage of reprogramming, LSD1 inhibition increased the retrovirus-mediated exogenous expression of Oct4, Klf4, and Sox2 by blocking related H3K4 demethylation. Since LSD1 inhibition still promoted reprogramming even when iPSCs were induced with small-molecule compounds in a virus-free system, additional mechanisms should be involved. When RNA-seq was used for analysis, it was found that LSD1 inhibition reversed some gene expression changes induced by OKS, which subsequently promoted reprogramming. For example, by partially rescuing the decreased expression of Hif1α, LSD1 inhibition reversed the up-regulation of genes in oxidative phosphorylation pathway and the down-regulation of genes in glycolysis pathway. Such effects facilitated the metabolic switch from oxidative phosphorylation to glycolysis and subsequently promoted iPSCs induction. In addition, LSD1 inhibition also promoted the conversion from pre-iPSCs to iPSCs by facilitating the similar metabolic switch. Therefore, LSD1 inhibition promotes reprogramming by facilitating the expression of exogenous transcriptional factors and metabolic switch.

Highlights

AP staining was performed to determining the efficiencies (n = 5)
An LSD1 inhibitor is included in the cocktail of small-molecule compounds which induces mouse somatic cells to induced pluripotent stem cells (iPSCs) (CiPSCs)[16]
The ability of LSD1 to promote oxidative metabolism of white adipose tissue suggested its potential involvement in the metabolic switch from oxidative to highly glycolytic at early stage of reprogramming[22,23]

Summary

Introduction

Since LSD1 occupies the enhancer and core promoters of some Oct4/Sox/Nanog-regulated targets[10], it is reasonable to propose interactions between LSD1 and pluripotency-related transcriptional factors (TFs). Because epigenetic regulation plays critical roles during the generation of induced pluripotent stem cells (iPSCs)[13,14], LSD1 has been studied extensively in this process. As a subunit of the larger LSD1 complex, the co-repressor Rcor[2] can substitute for Sox[2] during reprogramming, which is consistent with the critical functions of Sox[2] in regulating the sensitivity of cancer cells to LSD1 inhibition[18,19]. We aimed to further explore the functions of LSD1 during iPSC generation by determining the time-dependent regulatory roles of LSD1 inhibition, identifying the key effectors down-stream the inhibition, and demonstrating the potential influences on the metabolic switch from oxidative to glycolytic

Objectives

Methods

Results

Conclusion