BMAL1 coordinates energy metabolism and differentiation of pluripotent stem cells.

Cristina Ameneiro,Alba Coego,Alejandro Fuentes-Iglesias,Jose Maria Carvajal-Gonzalez,Diana Guallar,Vera Garcia-Outeiral,Sonia Mulero-Navarro,Daniel Torrecilla,Miguel Fidalgo,Adriana Escudero,Tiago Moreira

doi:10.26508/lsa.201900534

Abstract

BMAL1 is essential for the regulation of circadian rhythms in differentiated cells and adult stem cells, but the molecular underpinnings of its function in pluripotent cells, which hold a great potential in regenerative medicine, remain to be addressed. Here, using transient and permanent loss-of-function approaches in mouse embryonic stem cells (ESCs), we reveal that although BMAL1 is dispensable for the maintenance of the pluripotent state, its depletion leads to deregulation of transcriptional programs linked to cell differentiation commitment. We further confirm that depletion of Bmal1 alters the differentiation potential of ESCs in vitro. Mechanistically, we demonstrate that BMAL1 participates in the regulation of energy metabolism maintaining a low mitochondrial function which is associated with pluripotency. Loss-of-function of Bmal1 leads to the deregulation of metabolic gene expression associated with a shift from glycolytic to oxidative metabolism. Our results highlight the important role that BMAL1 plays at the exit of pluripotency in vitro and provide evidence implicating a non-canonical circadian function of BMAL1 in the metabolic control for cell fate determination.

Highlights

Circadian rhythms are necessary to coordinate key behavioural and physiological processes in mammals (Bechtold & Loudon, 2013; Lopez-Minguez et al, 2016; McAlpine & Swirski, 2016; Weger et al, 2017; Dierickx et al, 2018)
We did not observe major differences in typical embryonic stem cells (ESCs) morphology and AP staining in cells transduced with shRNAs against Bmal1 compared with silencing of Bmal1 compared with Luciferase control (shLuci) (Fig 1C)
We examined whether self-renewal properties of pluripotent cells were affected by the loss-of-function of Bmal1 in the presence

Summary

Introduction

Circadian rhythms are necessary to coordinate key behavioural (e.g., sleep/wake cycle) and physiological (e.g., metabolism, hormone secretion, and stem cell homeostasis) processes in mammals (Bechtold & Loudon, 2013; Lopez-Minguez et al, 2016; McAlpine & Swirski, 2016; Weger et al, 2017; Dierickx et al, 2018). Bmal KO mice have impaired circadian behaviour and absence of rhythmicity in circadian target genes (Bunger et al, 2000) They show infertility (Alvarez et al, 2008; Boden et al, 2010), show impaired glucose homeostasis (Rudic et al, 2004), and have been reported to have reduced life span and higher prevalence of age-related pathologies (Kondratov et al, 2006). Given that BMAL1 is readily expressed in ESCs, even in the absence of a functional circadian clock, we hypothesized that additional roles of this factor in pluripotency remain to be discovered and could yield insights into its function during early stages of embryonic development

Methods

Results

Conclusion