Dan-Fang Yu1, Zu-Cheng Shen1, Peng-Fei Wu1,2,3, Xin-Lei Guan1, Tao Chen1, You Jin1,2,3, Zhuang-Li Hu1,2,3, Lan Ni1,2,3, Fang Wang1,2,3,4, Jian-Guo Chen1,2,3,4, Li-Hong Long1,2,3,4. 1. Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. 2. The Key Laboratory of Neurological Diseases (HUST), Ministry of Education of China, Wuhan, China. 3. Hubei Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation (HUST), Wuhan, China. 4. The Laboratory of Neuropsychiatric Diseases, The Institute of Brain Research, Huazhong University of Science and Technology, Wuhan, China.
Abstract
BACKGROUND: The AMP-activated protein kinase (AMPK) is a sensor of cellular energy and nutrient status, with substantial amount of cross talk with other signaling pathways, including its phosphorylation by Akt, PKA, and GSK3β. AIMS: Various signaling pathways and energy-consuming transport of glutamate receptors subunits are required in synaptic plasticity. However, it is unknown which energy sensors integrate the signaling pathways in these processes. In this article, we elucidated the role of AMPK activation and GSK3β phosphorylation after HFS during the inducement of early-phase long-term potentiation (E-LTP). METHODS: Synaptic LTP in vivo was induced by high-frequency stimulation (HFS at 200 Hz at a 5-s interval). In addition, phosphorylation of AMPK and glycogen synthase kinase 3β (GSK3β) were measured using Western blotting. The amount of hippocampal AMP, ADP and ATP was measured by HPLC. RESULTS: We showed that the phosphorylation of AMPK and GSK3β was significantly increased by HFS in vivo. HFS-induced AMPK activation occurred via increased (AMP + ADP)/ATP ratio and activation of Ca(2+) /calmodulin-dependent kinase kinase beta (CaMKKβ). Pharmacological inhibition of AMPK by compound C (CC) prevented HFS-induced inhibitory phosphorylation of GSK3β and the induction of LTP in dentate gyrus (DG) area in vivo. CONCLUSIONS: Our findings reveal that HFS-triggered AMPK activation phosphorylates GSK3β and induces E-LTP in vivo.
BACKGROUND: The AMP-activated protein kinase (AMPK) is a sensor of cellular energy and nutrient status, with substantial amount of cross talk with other signaling pathways, including its phosphorylation by Akt, PKA, and GSK3β. AIMS: Various signaling pathways and energy-consuming transport of glutamate receptors subunits are required in synaptic plasticity. However, it is unknown which energy sensors integrate the signaling pathways in these processes. In this article, we elucidated the role of AMPK activation and GSK3β phosphorylation after HFS during the inducement of early-phase long-term potentiation (E-LTP). METHODS: Synaptic LTP in vivo was induced by high-frequency stimulation (HFS at 200 Hz at a 5-s interval). In addition, phosphorylation of AMPK and glycogen synthase kinase 3β (GSK3β) were measured using Western blotting. The amount of hippocampal AMP, ADP and ATP was measured by HPLC. RESULTS: We showed that the phosphorylation of AMPK and GSK3β was significantly increased by HFS in vivo. HFS-induced AMPK activation occurred via increased (AMP + ADP)/ATP ratio and activation of Ca(2+) /calmodulin-dependent kinase kinase beta (CaMKKβ). Pharmacological inhibition of AMPK by compound C (CC) prevented HFS-induced inhibitory phosphorylation of GSK3β and the induction of LTP in dentate gyrus (DG) area in vivo. CONCLUSIONS: Our findings reveal that HFS-triggered AMPK activation phosphorylates GSK3β and induces E-LTP in vivo.