Ammonia plays an important role in cellular metabolism. However, ammonia is considered a toxic product. In bone marrow-derived mesenchymal stem cells, multipotent stem cells with high expression of glutamine synthetase (GS) in bone marrow, ammonia and glutamate can be converted to glutamine via glutamine synthetase activity to support the proliferation of MSCs. As a major nutritional amino acid for biosynthesis, glutamine can activate the Akt/mTOR/S6k pathway to stimulate cell proliferation. The activation of mTOR can promote cell entry into S phase, thereby enhancing DNA synthesis and cell proliferation. Our studies demonstrated that mesenchymal stem cells can convert the toxic waste product ammonia into nutritional glutamine via GS activity. Then, the Akt/mTOR/S6k pathway is activated to promote bone marrow-derived mesenchymal stem cell proliferation. These results suggest a new therapeutic strategy and potential target for the treatment of diseases involving hyperammonemia.
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