Mitochondrial Phosphoenolpyruvate Carboxykinase Regulates Osteogenic Differentiation by Modulating AMPK/ULK1-Dependent Autophagy.

Mitochondrial phosphoenolpyruvate carboxykinase (PCK2) is a rate-limiting enzyme that plays critical roles in multiple physiological processes. The decompensation of PCK2 leads to various energy metabolic disorders. However, little is known regarding the effects of PCK2 on osteogenesis by human mesenchymal stem cells (hMSCs). Here, we report a novel function of PCK2 as a positive regulator of MSCs osteogenic differentiation. In addition to its well-known role in anabolism, we demonstrate that PCK2 regulates autophagy. PCK2 deficiency significantly suppressed autophagy, leading to the impairment of osteogenic capacity of MSCs. On the other hand, autophagy was promoted by PCK2 overexpression; this was accompanied by increased osteogenic differentiation of MSCs. Moreover, PCK2 regulated osteogenic differentiation of MSCs via AMP-activated protein kinase (AMPK)/unc-51 like autophagy activating kinase 1(ULK1)-dependent autophagy. Collectively, our present study unveiled a novel role for PCK2 in integrating autophagy and bone formation, providing a potential target for stem cell-based bone tissue engineering that may lead to improved therapies for metabolic bone diseases. Stem Cells 2019;37:1542-1555.