Promoter activity of the beta-amyloid precursor protein gene is negatively modulated by an upstream regulatory element

Debomoy K. Lahiri, Christina Nall, Yuan Wen Ge

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Alzheimer's disease (AD) is characterized by the aggregation of the amyloid beta-peptide (Aβ) which is generated from a larger beta-amyloid precursor protein (βAPP). An overexpression of the βAPP gene in certain areas of the AD brain has been suggested to be an important factor in the neuropathology of AD. Here we have further characterized an upstream regulatory element (URE) located between -2257 and -2234 of the human βAPP promoter. In addition to its location in the promoter, BLAST search reveals that URE is present in several introns of the βAPP gene and is also detected in many other genes. For functional studies, two promoter regions were cloned upstream of the reporter gene, chloramphenicol acetyl transferase (CAT): (i) phβE-B - the plasmid that contains the human (h) promoter region (-2832 to +101) including URE, and (ii) prhβE-B - the plasmid that contains the rhesus (rh) promoter region excluding URE as it lacks a 270 bp region of the hβAPP promoter (-2435 to -2165). Transient transfection studies indicate that phβE-B displayed significantly less CAT-promoter activity than prhβE-B in C6, PC12 and SK-N-SH cells. To determine the role of URE in a heterologous promoter, a pβURE construct was made by subcloning URE in an enhancerless promoter vector pCATP. The pβURE-CAT construct displayed threefold to fourfold less promoter activity than pCATP when different cell lines were transfected with the plasmids. URE interacts with a novel protein(s) as determined by the electrophoretic mobility shift assay (EMSA). Although the core DNA region of URE resembles with the NF-kB element, URE-binding protein is not related to the NF-kB transcription factor. When EMSA was performed with specific competitors in different cell lines, the labeled URE probe was not competed by the oligonucleotides specific for either the AP3, NF-1 or NF-kB transcription factor. The migration of the URE-protein complex was different from the NF-kB-protein complex in the EMSA gel. A distinct URE-specific nuclear factor was also detected in frontal cortex of a normal human brain. These results suggest that the URE region acts as a repressor element, that the URE-binding protein is not related to the known transcription factors tested, and that the protein is present in astrocytic, neuroblastoma, PC12 cells and in the human brain. Copyright (C) 1999 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)32-41
Number of pages10
JournalMolecular Brain Research
Volume71
Issue number1
DOIs
StatePublished - Jul 23 1999
Externally publishedYes

Keywords

  • APP
  • Beta-peptide
  • Gel shift assay
  • Gene regulation
  • Nuclear factor
  • Transcription

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience

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