Role of Glutamine Metabolism During Osteoblast Differentiation and Bone Formation

项目总结： 谷氨酰胺是一种条件性必需氨基酸，在细胞中有多种用途。除了直接 结合到蛋白质中，谷氨酰胺可以在代谢后生成核苷酸、其他氨基酸、ATP 进入三氯乙酸循环，谷胱甘肽保护免受氧化应激。目前还不清楚是如何做到的 成骨细胞利用谷氨酰胺，并在分化过程中需要时利用谷氨酰胺。我们最近发现了谷氨酰胺酶 (GLS)是WNT依赖的病理性骨形成的关键调节因子。GLS使谷氨酰胺脱氨基 形成谷氨酸，谷氨酰胺代谢的第一步。使用药理学方法，我们证明了 在LRP5人类高骨量病小鼠模型中，GLS活性是骨形成所必需的。 重要的是，抑制GLS对其他野生型小鼠的骨量没有影响，表明GLS和谷氨酰胺 小鼠生理性骨形成可能不需要新陈代谢。在这份提案中，我们将1)建立 谷氨酰胺酶(GLS)调节成骨细胞分化和骨形成的必要性和充分性 确定WNT对GLS活性的分子调节，以及3)了解谷氨酰胺是如何代谢的 在间充质干细胞中。我们的发现将对骨骼的发育、维持 骨量、骨骼修复和再生，以及确定刺激谷氨酰胺代谢是否可行 骨合成代谢靶点，刺激骨形成。

Project Summary: Glutamine is a conditionally essential amino acid that has myriad uses in the cell. Aside from direct incorporation into protein, glutamine can be metabolized to generate nucleotides, other amino acids, ATP after anaplerosis into the TCA cycle, and glutathione to protect against oxidative stress. It is unknown how osteoblasts utilize glutamine and when it is required during differentiation. We recently identified glutaminase (GLS) as a critical regulator of Wnt dependent pathological bone formation. GLS deaminates glutamine to form glutamate, the first step in glutamine metabolism. Using a pharmacological approach, we demonstrated GLS activity was required for bone formation in the LRP5 human high bone mass disease mouse model. Importantly, GLS inhibition did not affect bone mass in otherwise wild type mice indicating GLS and glutamine metabolism may not be required for physiological bone formation in mice. In this proposal, we will 1) establish the necessity and sufficiency of glutaminase (GLS) to regulate osteoblast differentiation and bone formation, 2) determine if the molecular regulation of GLS activity by WNT, and 3) understand how glutamine is metabolized in mesenchymal stem cells. Our findings will have broad implications in bone development, maintenance of bone mass, skeletal repair and regeneration, as well as identify if stimulating glutamine metabolism is a viable osteoanabolic target to stimulate bone formation.