Mitochondrial oxidative metabolism is required for the cardiac differentiation of stem cells

Abstract

SUMMARYCardiogenesis within embryos or associated with heart repair requires stem cell differentiation into energetically competent, contracting cardiomyocytes. While it is widely accepted that the coordination of genetic circuits with developmental bioenergetics is critical to phenotype specification, the metabolic mechanisms that drive cardiac transformation are largely unknown. Here, we aim to define the energetic requirements for and the metabolic microenvironment needed to support the cardiac differentiation of embryonic stem cells. We demonstrate that anaerobic glycolytic metabolism, while sufficient for embryonic stem cell homeostasis, must be transformed into the more efficient mitochondrial oxidative metabolism to secure cardiac specification and excitation-contraction coupling. This energetic switch was programmed by rearrangement of the metabolic transcriptome that encodes components of glycolysis, fatty acid oxidation, the Krebs cycle, and the electron transport chain. Modifying the copy number of regulators of mitochondrial fusion and fission resulted in mitochondrial maturation and network expansion, which in turn provided an energetic continuum to supply nascent sarcomeres. Disrupting respiratory chain function prevented mitochondrial organization and compromised the energetic infrastructure, causing deficient sarcomerogenesis and contractile malfunction. Thus, establishment of the mitochondrial system and engagement of oxidative metabolism are prerequisites for the differentiation of stem cells into a functional cardiac phenotype. Mitochondria-dependent energetic circuits are thus critical regulators of de novo cardiogenesis and targets for heart regeneration.

Mitochondrial Reactive Oxygen Species Mediate Cardiomyocyte Formation from Embryonic Stem Cells in High Glucose

“…to underphosphorylated p38 in ES cells [25] and also in endothelial cells [44,45], and we found that both p38 phosphorylation and NOX4 transcription are downregulated during low glucose differentiation. Interestingly, Nox4 has been recently reported to reside in the mitochondrion of the kidney cortex, and its expression is sensitive to glucose levels [46].…”

“…More specifically, we assessed the potential of ES cells to develop cardiomyocyte structures, as the switch from glycolysis to mitochondrial metabolism has been shown to be linked to cardiac differentiation [25]. After 2 days as hanging-drops, EBs aggregated in either high or low glucose had a similar morphological appearance and size (not shown), indicating that the medium glucose concentration did not perturb simple EB formation.…”

Cited2, a Transcriptional Modulator Protein, Regulates Metabolism in Murine Embryonic Stem Cells

“…During ESCs differentiating to cardiomyocytes, the rate of lactate production, normalized by time and total protein mass was reported to be reduced to 2-fold, supporting the notion that metabolic reprogramming is essential for proper ESC differentiation (19). We previously demonstrated that Cited2 ⌬/Ϫ ESCs exhibit defective cardiomyocyte and hematopoietic differentiation during normoxia (22).…”

“…In the early stages of differentiation into epiblast stem cells, 98% of glucose is consumed for lactate production (14). At mid-to-late differentiation, ESCs undergo a metabolic switch from glycolysis to mitochondrial oxidative phosphorylation to provide sufficient ATP for differentiation (19,20). A metabolic switch from oxidative phosphorylation to glycolysis would thus favor reprogramming of terminally differentiated mouse fibroblasts to induced pluripotent stem cells (21).…”

A cut short to death: Parl and Opa1 in the regulation of mitochondrial morphology and apoptosis

“…Along this line, during differentiation from embryonic stem cells into cardiomyocytes, the remarkable changes in mitochondrial ultrastructure and reticular organization are accompanied by the reduction in the levels of Opa1 and by the upregulation of Mfn2. This is likely coordinated with the metabolic switch from glycolytic to oxidative; 30 indeed, the repression of Mfn2 in myofibres reduces myocyte respiration, further supporting the liaison between this protein and mitochondrial oxidative metabolism. 29 …”