Human adipose-derived stromal cells (hASCs) are attractive for regenerative medicine, but their limited in vitro lifespan limits their therapeutic applicability. Recent data demonstrate that hypoxia may benefit the ex vivo culture of stem cells. Such cells exhibit a high level of glycolytic metabolism under hypoxic conditions. However, the physiological role of glycolytic activation and its underlying regulatory mechanism are incompletely understood. We have shown that when activated under conditions of 5% O₂, Notch signaling dramatically increases the rate of glycolysis, improves proliferation efficiency, prevents senescence, and maintains the multipotency of hASCs. In the present study, we found that activated Notch1 enhanced nuclear p65 levels, resulting in an increase in glucose metabolism through the upregulation of glycolytic factors including GLUT3. Notch signaling was also involved in glucose metabolism through p53 inactivation. We also found that NF-¿B signaling was regulated by p53. These data suggest that Notch-HES1 signaling enhances the glycolytic pathway through p53 and NF-¿B. Our data also revealed that activated Notch1 markedly increased the transcriptional activity of hypoxia-inducible factor 1 (HIF-1). Knockdown of HIF-1a significantly attenuated glycolysis induced by activated Notch1, indicating that the glycolysis pathway is regulated by the coordination of Notch signaling and HIF. Overall, our observations provide new regulatory mechanisms for the glycolysis by Notch signaling to maintain the stemness of hASCs.

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