Cellular level/distribution of γ-secretase subunit nicastrin and its modulator p23 in the brain

  • Author / Creator
    Kodam, Anitha
  • The processing of amyloid precursor protein (APP) by β- and γ-secretases produces amyloid β (Aβ) peptide, the principal component of the neuritic plaques found in Alzheimer’s disease (AD) pathology. The enzyme γ-secretase is a multimeric protein consisting of presenilins-1/2 (PS1/PS2), nicastrin, anterior pharynx defective 1 (APH-1) and presenilin enhancer-2 (PEN-2). Recently it was discovered that p23, a transmembrane protein involved in intracellular protein trafficking, negatively regulates γ-secretase activity. In the present study, I evaluated the levels/expression of the nicastrin and p23 and their possible colocalization with PS1 in normal adult and developing brains. Additionally, I have studied the alterations of p23 levels in both animal model of neurodegeneration and in postmortem AD brains. Nicastrin and p23 were widely distributed throughout the brain and colocalized in all brain regions with PS1. The levels of nicastrin and p23 were relatively high at the early stages of postnatal development and then declined gradually as age increased. Interestingly, p23 level/expression was found to be altered following kainic acid-induced neurodegeneration in the adult rat brain. Additionally, p23 levels were reduced in the brains of individuals with AD. These results, taken together, suggest that both nicastrin and p23 are expressed in neurons throughout the brain and their levels decline gradually during development to reach an adult profile. Additionally, my results indicate that a decreased level of p23 may contribute to AD pathogenesis by increasing the production of Aβ-related peptides.

  • Subjects / Keywords
  • Graduation date
    Spring 2010
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.