RESUMEN
Effective lineage-specific differentiation is essential to fulfilling the great potentials of human pluripotent stem cells (hPSCs). In this report, we investigate how modulation of medium pH and associated metabolic changes influence mesendoderm differentiation from hPSCs. We show that daily medium pH fluctuations are critical for the heterogeneity of cell fates in the absence of exogenous inducers. Acidic environment alone leads to cardiomyocyte generation without other signaling modulators. In contrast, medium alkalinization is inhibitory to cardiac fate even in the presence of classic cardiac inducers. We then demonstrate that acidic environment suppresses glycolysis to facilitate cardiac differentiation, while alkaline condition promotes glycolysis and diverts the differentiation toward other cell types. We further show that glycolysis inhibition or AMPK activation can rescue cardiac differentiation under alkalinization, and glycolysis inhibition alone can drive cardiac cell fate. This study highlights that pH changes remodel metabolic patterns and modulate signaling pathways to control cell fate.
Asunto(s)
Diferenciación Celular , Glucólisis , Miocitos Cardíacos , Células Madre Pluripotentes , Humanos , Diferenciación Celular/efectos de los fármacos , Células Madre Pluripotentes/metabolismo , Células Madre Pluripotentes/citología , Células Madre Pluripotentes/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/citología , Miocitos Cardíacos/efectos de los fármacos , Concentración de Iones de Hidrógeno , Acidosis/metabolismo , Endodermo/citología , Endodermo/metabolismo , Linaje de la Célula/efectos de los fármacos , Mesodermo/citología , Mesodermo/metabolismo , Medios de Cultivo/farmacología , Medios de Cultivo/química , Transducción de Señal/efectos de los fármacos , Línea Celular , Proteínas Quinasas Activadas por AMP/metabolismoRESUMEN
Insulin is an essential growth factor for the survival and self-renewal of human embryonic stem cells (hESCs). Although it is best known as the principal hormone promoting glycolysis in somatic cells, insulin's roles in hESC energy metabolism remain unclear. In this report, we demonstrate that insulin is essential to sustain hESC mitochondrial respiration that is rapidly decreased upon insulin removal. Insulin-dependent mitochondrial respiration is stem cell specific, and mainly relies on pyruvate and glutamine, while glucose suppresses excessive oxidative phosphorylation. Pharmacologic and genetic manipulations reveal that continuous insulin signal sustains mitochondrial respiration through PI3K/AKT activation and downstream GSK3 inhibition. We further show that insulin acts through GSK3 inhibition to suppress caspase activation and rescue cell survival. This study uncovers a critical role of the AKT/GSK3 pathway in the regulation of mitochondrial respiration and cell survival, highlighting insulin as an essential factor for accurate assessment of mitochondrial respiration in hESCs.