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  2. Inactivated AMPK-α2 promotes the progression of diabetic brain damage by Cdk5 phosphorylation at Thr485 site

Inactivated AMPK-α2 promotes the progression of diabetic brain damage by Cdk5 phosphorylation at Thr485 site

  • Biochimie. 2020 Jan;168:277-284. doi: 10.1016/j.biochi.2019.11.010.
Yan Li 1 Qiong Xiang 2 Yu-Han Yao 1 Jing-Jing Li 1 Yan Wang 3 Xian-Hui Li 4
Affiliations

Affiliations

  • 1 College of Medicine, Jishou University, Hunan Province, PR China.
  • 2 Institute of Medicine, Medical Research Center, Hunan Engineering Laboratory for Analyse and Drugs Development of Ethnomedicine in Wuling Mountains, Jishou University, Hunan Province, PR China.
  • 3 Pharmacy Department, The First People's Hospital of Foshan, Foshan City, Guang Dong Province, PR China.
  • 4 Institute of Medicine, Medical Research Center, Hunan Engineering Laboratory for Analyse and Drugs Development of Ethnomedicine in Wuling Mountains, Jishou University, Hunan Province, PR China. Electronic address: lxh_surgeon@yeah.net.
Abstract

Changes in brain energy metabolism in diabetes mellitus, including increased Insulin resistance and mitochondrial dysfunction, are critically involved in diabetes-related neurodegeneration, and associate with early cognitive impairment as well. The aim of this study is to detect the specific phosphorylated-Thr485- AMP-activated protein kinase (AMPK-α2), regulated by cyclin-dependent kinase 5 (CDK5) paly the inhibitory functional role of AMPK-α2, Which is maybe the link to the accelerated diabetic brain damage progression. Here, we used GK rats, the type 2 diabetic animal model for in vivo studies and performed In vitro kinase assay, high glucose treatment, -phosphorylated mutation and protein expression in both HEK-293T and HT-22 cell lines. In vitro, the results show that murine wild-type AMPK-α2 was phosphorylated by CDK5 at a (S/T)PX(K/H/R) phosphorylation consensus sequence, which was associated with decreased AMPK-α2 activity. Surprisingly, mutation of Thr485 to alanine in AMPK-α2 results in the abolished CDK5 effects, demonstrating that Thr485-phosphorylation is critical to AMPK-α2 inhibition by CDK5. In addition, these alterations in AMPK-α2-phosphorylation and -activity induced by CDK5 is specific at Thr485. Furthermore, in GK rats, the increased phosphorylated- Thr 485 of AMPK-α2 results in the decreased AMPK-α2 activity, which is correlated with the Apoptosis of neurons in hippocamps. After high glucose treatment, the decreased survival showed in AMPK-α2T485A HT-22 cells compared to AMPK-α2WT. The down-regulated of p-CREB, SNAP25, synaptophysin as well as synapsin-1were shown in both GK rats and HT-22 cell line. Meanwhile, pre-treated with either the specific Cdk5-inhibitor (roscovitine) or the antidiabetic AMPK-α2-inhibitor (metformin) could restore the alterations in neuronal protein expression. Our results suggest that Cdk5-mediated phosphorylated- Thr485 in AMPK-α2 may be involved in the pathogenesis of diabetic brain damage.

Keywords

AMP-Activated protein kinase; Cyclin-dependent kinase 5; Diabetic brain damage; Neurometabolic disorders; Phosphorylated- Thr485.

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