Aryl Sulfonamide Inhibitors of Insulin-Regulated Aminopeptidase Enhance Spine Density in Primary Hippocampal Neuron Cultures

ACS Chem Neurosci. 2016 Oct 19;7(10):1383-1392. doi: 10.1021/acschemneuro.6b00146. Epub 2016 Aug 8.


The zinc metallopeptidase insulin regulated aminopeptidase (IRAP), which is highly expressed in the hippocampus and other brain regions associated with cognitive function, has been identified as a high-affinity binding site of the hexapeptide angiotensin IV (Ang IV). This hexapeptide is thought to facilitate learning and memory by binding to the catalytic site of IRAP to inhibit its enzymatic activity. In support of this hypothesis, low molecular weight, nonpeptide specific inhibitors of IRAP have been shown to enhance memory in rodent models. Recently, it was demonstrated that linear and macrocyclic Ang IV-derived peptides can alter the shape and increase the number of dendritic spines in hippocampal cultures, properties associated with enhanced cognitive performance. After screening a library of 10 500 drug-like substances for their ability to inhibit IRAP, we identified a series of low molecular weight aryl sulfonamides, which exhibit no structural similarity to Ang IV, as moderately potent IRAP inhibitors. A structural and biological characterization of three of these aryl sulfonamides was performed. Their binding modes to human IRAP were explored by docking calculations combined with molecular dynamics simulations and binding affinity estimations using the linear interaction energy method. Two alternative binding modes emerged from this analysis, both of which correctly rank the ligands according to their experimental binding affinities for this series of compounds. Finally, we show that two of these drug-like IRAP inhibitors can alter dendritic spine morphology and increase spine density in primary cultures of hippocampal neurons.

Keywords: Insulin-regulated aminopeptidase; aryl sulfonamides; dendritic spines; hippocampal neurons; ligand interaction energy simulations; molecular dynamics.

MeSH terms

  • Animals
  • CD13 Antigens / metabolism
  • Cells, Cultured
  • Coculture Techniques
  • Cystinyl Aminopeptidase / antagonists & inhibitors*
  • Cystinyl Aminopeptidase / metabolism
  • Dendritic Spines / drug effects*
  • Dendritic Spines / enzymology
  • Drug Evaluation, Preclinical
  • Enzyme Inhibitors / chemical synthesis
  • Enzyme Inhibitors / pharmacology*
  • Epoxide Hydrolases / genetics
  • Epoxide Hydrolases / metabolism
  • HEK293 Cells
  • Hippocampus / cytology*
  • Hippocampus / drug effects
  • Hippocampus / enzymology
  • Humans
  • Molecular Docking Simulation
  • Molecular Dynamics Simulation
  • Molecular Structure
  • Protein Binding
  • Rats, Sprague-Dawley
  • Recombinant Proteins / genetics
  • Sulfonamides / chemical synthesis
  • Sulfonamides / pharmacology*


  • Enzyme Inhibitors
  • Recombinant Proteins
  • Sulfonamides
  • Epoxide Hydrolases
  • CD13 Antigens
  • Cystinyl Aminopeptidase
  • leucyl-cystinyl aminopeptidase
  • leukotriene A4 hydrolase