Deletion of the cathepsin B gene improves memory deficits in a transgenic ALZHeimer's disease mouse model expressing AβPP containing the wild-type β-secretase site sequence

J Alzheimers Dis. 2012;29(4):827-40. doi: 10.3233/JAD-2012-111604.


Therapeutic agents that improve the memory loss of Alzheimer's disease (AD) may eventually be developed if drug targets are identified that improve memory deficits in appropriate AD animal models. One such target is β-secretase which, in most AD patients, cleaves the wild-type (WT) β-secretase site sequence of the amyloid-β protein precursor (AβPP) to produce neurotoxic amyloid-β (Aβ). Thus, an animal model representing most AD patients for evaluating β-secretase effects on memory deficits is one that expresses human AβPP containing the WT β-secretase site sequence. BACE1 and cathepsin B (CatB) proteases have β-secretase activity, but gene knockout studies have not yet validated that the absence of these proteases improves memory deficits in such an animal model. This study assessed the effects of deleting these protease genes on memory deficits in the AD mouse model expressing human AβPP containing the WT β-secretase site sequence and the London γ-secretase site (AβPPWT/Lon mice). Knockout of the CatB gene in the AβPPWT/Lon mice improved memory deficits and altered the pattern of Aβ-related biomarkers in a manner consistent with CatB having WT β-secretase activity. But deletion of the BACE1 gene had no effect on these parameters in the AβPPWT/Lon mice. These data are the first to show that knockout of a putative β-secretase gene results in improved memory in an AD animal model expressing the WT β-secretase site sequence of AβPP, present in the majority of AD patients. CatB may be an effective drug target for improving memory deficits in most AD patients.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Alzheimer Disease / complications*
  • Alzheimer Disease / genetics
  • Alzheimer Disease / pathology
  • Amyloid Precursor Protein Secretases / deficiency
  • Amyloid beta-Peptides / metabolism
  • Amyloid beta-Protein Precursor / genetics
  • Amyloid beta-Protein Precursor / metabolism*
  • Analysis of Variance
  • Animals
  • Aspartic Acid Endopeptidases / deficiency
  • Brain / metabolism
  • Brain / pathology
  • Cathepsin B / deficiency*
  • Disease Models, Animal
  • Enzyme-Linked Immunosorbent Assay
  • Gene Expression Regulation / genetics
  • Humans
  • Maze Learning / physiology
  • Memory Disorders / etiology*
  • Memory Disorders / genetics*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Mutation / genetics*
  • Peptide Fragments / metabolism
  • Plaque, Amyloid / pathology
  • Reaction Time / genetics


  • Amyloid beta-Peptides
  • Amyloid beta-Protein Precursor
  • Peptide Fragments
  • amyloid beta-protein (1-40)
  • amyloid beta-protein (1-42)
  • Amyloid Precursor Protein Secretases
  • Cathepsin B
  • Aspartic Acid Endopeptidases
  • Bace1 protein, mouse