Role of Glutamine Metabolism During Osteoblast Differentiation and Bone Formation

项目概要： 谷氨酰胺是一种条件性必需氨基酸，在细胞中有无数用途。除了直接 当谷氨酰胺掺入蛋白质中时，谷氨酰胺可以代谢产生核苷酸、其它氨基酸、ATP， 回补进入TCA循环，谷胱甘肽保护免受氧化应激。不知道是怎么回事 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。我们最近发现了转氨酶 (GLS)作为Wnt依赖性病理性骨形成的关键调节剂。GLS使谷氨酰胺脱氨， 形成谷氨酸，这是谷氨酰胺代谢的第一步。使用药理学方法，我们证明了 在LRP 5人高骨量疾病小鼠模型中，骨形成需要GLS活性。 重要的是，GLS抑制不影响其他野生型小鼠的骨量，表明GLS和谷氨酰胺 代谢可能不是小鼠生理骨形成所必需的。在本提案中，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，2） 确定WNT是否对GLS活性进行分子调节，以及3）了解谷氨酰胺是如何代谢的 间充质干细胞我们的研究结果将对骨骼发育、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是一种可行的 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.