A PDK-1 allosteric agonist neutralizes insulin signaling derangements and beta-amyloid toxicity in neuronal cells and in vitro

PLoS One. 2022 Jan 21;17(1):e0261696. doi: 10.1371/journal.pone.0261696. eCollection 2022.

Abstract

The Alzheimer's brain is affected by multiple pathophysiological processes, which include a unique, organ-specific form of insulin resistance that begins early in its course. An additional complexity arises from the four-fold risk of Alzheimer's Disease (AD) in type 2 diabetics, however there is no definitive proof of causation. Several strategies to improve brain insulin signaling have been proposed and some have been clinically tested. We report findings on a small allosteric molecule that reverses several indices of insulin insensitivity in both cell culture and in vitro models of AD that emphasize the intracellular accumulation of β-amyloid (Aβi). PS48, a chlorophenyl pentenoic acid, is an allosteric activator of PDK-1, which is an Akt-kinase in the insulin/PI3K pathway. PS48 was active at 10 nM to 1 μM in restoring normal insulin-dependent Akt activation and in mitigating Aβi peptide toxicity. Synaptic plasticity (LTP) in prefrontal cortical slices from normal rat exposed to Aβ oligomers also benefited from PS48. During these experiments, neither overstimulation of PI3K/Akt signaling nor toxic effects on cells was observed. Another neurotoxicity model producing insulin insensitivity, utilizing palmitic acid, also responded to PS48 treatment, thus validating the target and indicating that its therapeutic potential may extend outside of β-amyloid reliance. The described in vitro and cell based-in vitro coupled enzymatic assay systems proved suitable platforms to screen a preliminary library of new analogs.

MeSH terms

  • 3-Phosphoinositide-Dependent Protein Kinases / antagonists & inhibitors
  • 3-Phosphoinositide-Dependent Protein Kinases / metabolism*
  • Allosteric Regulation / drug effects
  • Alzheimer Disease / metabolism*
  • Amyloid beta-Peptides / metabolism*
  • Animals
  • Cell Line, Tumor
  • Humans
  • Insulin / metabolism*
  • Mice
  • Neurons / metabolism*
  • Pentanoic Acids / pharmacology*
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction / drug effects*

Substances

  • 5-(4-chlorophenyl)-3-phenyl-pent-2-enoic acid
  • Amyloid beta-Peptides
  • Insulin
  • Pentanoic Acids
  • 3-Phosphoinositide-Dependent Protein Kinases
  • PDPK1 protein, human
  • Pdpk1 protein, mouse
  • Pdpk1 protein, rat

Grants and funding

This study was funded by the National Institute of Health, National Institute on Aging (NIA): NIH AG044871-01 (HWQ), The Brown Institute for Brain Science and Norman Prince Neuroscience Institute (HWQ, JM), and through an award from the Bennett Foundation (HWQ). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.