Xuzhou Engineering Research Center of Medical Genetics and Transformation, Department of Genetics, Xuzhou Medical University, Xuzhou, Jiangsu, China.
The Graduate School, Xuzhou Medical University, Xuzhou, Jiangsu, China.
CNS Neurosci Ther. 2024 Mar;30(3):e14449. doi: 10.1111/cns.14449. Epub 2023 Sep 4.
Chronic hyperglycemia-induced inflammation of the hippocampus is an important cause of cognitive deficits in diabetic patients. The receptor for advanced glycation end products (RAGE), which is widely expressed in the hippocampus, is a crucial factor in this inflammation and the associated cognitive deficits. We aimed to reveal the underlying mechanism by which RAGE regulates neuroinflammation in the pathogenesis of diabetes-induced cognitive impairment.
We used db/db mice as a model for type 2 diabetes to investigate whether receptor-interacting serine/threonine protein kinase 1 (RIPK1), which is expressed in microglia in the hippocampal region, is a key protein partner for RAGE. GST pull-down assays and AutoDock Vina simulations were performed to identify the key structural domain in RAGE that binds to RIPK1. Western blotting, co-immunoprecipitation (Co-IP), and immunofluorescence (IF) were used to detect the levels of key proteins or interaction between RAGE and RIPK1. Cognitive deficits in the mice were assessed with the Morris water maze (MWM) and new object recognition (NOR) and fear-conditioning tests.
RAGE binds directly to RIPK1 via the amino acid sequence (AAs) 362-367, thereby upregulating phosphorylation of RIPK1, which results in activation of the NLRP3 inflammasome in microglia and ultimately leads to cognitive impairments in db/db mice. We mutated RAGE AAs 362-367 to reverse neuroinflammation in the hippocampus and improve cognitive function, suggesting that RAGE AAs 362-367 is a key structural domain that binds directly to RIPK1. These results also indicate that hyperglycemia-induced inflammation in the hippocampus is dependent on direct binding of RAGE and RIPK1.
Direct interaction of RAGE and RIPK1 via AAs 362-367 is an important mechanism for enhanced neuroinflammation in the hyperglycemic environment and is a key node in the development of cognitive deficits in diabetes.
慢性高血糖引起的海马体炎症是糖尿病患者认知功能障碍的重要原因。在海马体中广泛表达的晚期糖基化终产物（RAGE）受体是这种炎症及相关认知缺陷的关键因素。我们旨在揭示 RAGE 通过何种机制调节神经炎症，从而在糖尿病引起的认知障碍发病机制中发挥作用。
我们使用 db/db 小鼠作为 2 型糖尿病模型，研究在海马区表达的受体相互作用丝氨酸/苏氨酸蛋白激酶 1（RIPK1）是否是 RAGE 的关键蛋白伴侣。采用 GST 下拉实验和 AutoDock Vina 模拟实验确定 RAGE 与 RIPK1 结合的关键结构域。采用 Western blot、免疫共沉淀（Co-IP）和免疫荧光（IF）检测关键蛋白水平或 RAGE 与 RIPK1 之间的相互作用。采用 Morris 水迷宫（MWM）、新物体识别（NOR）和恐惧条件反射测试评估小鼠的认知缺陷。
RAGE 通过氨基酸序列（AAs）362-367 直接与 RIPK1 结合，从而上调 RIPK1 的磷酸化，导致小胶质细胞中 NLRP3 炎性体的激活，最终导致 db/db 小鼠的认知障碍。我们突变 RAGE AAs 362-367 以逆转海马体的神经炎症并改善认知功能，这表明 RAGE AAs 362-367 是直接与 RIPK1 结合的关键结构域。这些结果还表明，海马体的高血糖诱导炎症依赖于 RAGE 和 RIPK1 的直接结合。
RAGE 和 RIPK1 通过 AAs 362-367 的直接相互作用是高血糖环境中增强神经炎症的重要机制，也是糖尿病认知功能障碍发展的关键节点。
