The beta-amyloid precursor protein (APP) is an extensively processed membrane protein with a single membrane spanning domain. One of the natural proteolytic products of APP is a peptide of 39 to 43 amino acids in length, beta-amyloid, that has been identified as a major constituent of senile plaques, a neuropathological hallmark of Alzheimer disease (AD). In Down syndrome (DS) (trisomy 21), overexpression of the APP gene, located on chromosome 21, is thought to be responsible for the early formation of senile plaques in the brain of DS patients. We investigated the transcriptional regulation of the APP gene in order to identify the cis-elements located in its promoter and the trans-acting factors recognizing these elements. Identification of the factors regulating APP gene expression, could help define conditions leading to the development of AD. The APP promoter possesses multiple transcriptional start sites, has a high percentage of GC and lacks a consensus TATA box. We have characterized, using electrophoretic mobility shift analysis (EMSA), DNase I footprinting, site-directed mutagenesis and transient transfection studies, three elements located in close proximity of the major transcriptional start sites of APP. We present evidence that two of the elements are recognized by the ubiquitous transcription factors Sp1 and USF respectively. Both the Sp1 and USF elements are essential for full activity of the APP promoter, regulate the APP promoter in an additive manner and synergize with the factor(s) recognizing a GC-rich element located upstream in transient transfection assays in NG108-15 and HepG2 cell lines. We also show that treatment by cyclic AMP of NG108-15 cells which had been transiently transfected with reporter constructs driven by different portions of the APP promoter caused an increase in reporter gene activity mediated by sequences located between --2991 to --488 and --303 to --204, even though the upstream sequences of APP do not contain a canoni
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.34702 |
| Date | January 1997 |
| Creators | Bourbonnière, Martin. |
| Contributors | Nalbautoglu, Josephine (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Neurology and Neurosurgery.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001601729, proquestno: NQ44367, Theses scanned by UMI/ProQuest. |
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