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. Epub 2019 Nov 29.

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.

MeSH terms

  • AMP-Activated Protein Kinases / antagonists & inhibitors
  • AMP-Activated Protein Kinases / metabolism*
  • Animals
  • Cell Line
  • Cyclin-Dependent Kinase 5 / antagonists & inhibitors
  • Cyclin-Dependent Kinase 5 / physiology*
  • Diabetes Mellitus* / metabolism
  • Diabetes Mellitus* / pathology
  • HEK293 Cells
  • Hippocampus* / metabolism
  • Hippocampus* / pathology
  • Humans
  • Male
  • Metformin / metabolism
  • Mice
  • Neurons* / metabolism
  • Neurons* / pathology
  • Rats
  • Roscovitine / metabolism

Substances

  • Roscovitine
  • Metformin
  • AMPK alpha2 subunit, mouse
  • Cyclin-Dependent Kinase 5
  • Prkaa2 protein, rat
  • Cdk5 protein, mouse
  • Cdk5 protein, rat
  • AMP-Activated Protein Kinases