Expression of BRI–amyloid β peptide fusion proteins: a novel method for specific high-level expression of amyloid β peptides

Abstract

In order to develop transgenic animal models that selectively overexpress various Abeta peptides, we have developed a novel expression system that selectively expresses Abeta40 or Abeta42 in the secretory pathway. This system utilizes fusion constructs in which the sequence encoding the 23-amino-acid ABri peptide at the carboxyl terminus of the 266-amino-acid type 2 transmembrane protein BRI is replaced with a sequence encoding either Abeta40 or Abeta42. Constitutive processing of the resultant BRI-Abeta fusion proteins in transfected cells results in high-level expression and secretion of the encoded Abeta peptide. Significantly, expression of Abeta42 from the BRI-Abeta42 construct resulted in no increase in secreted Abeta40, suggesting that the majority of Abeta42 is not trimmed by carboxypeptidase to Abeta40 in the secretory pathway.

γ-Secretase Processing and Effects of γ-Secretase Inhibitors and Modulators on Long Aβ Peptides in Cells

“…DNA and Cell Culture-Fusion constructs encoding the first 243 amino acids of BRI2 protein followed by A␤ peptides encompassing various A␤ species from A␤38 to A␤55 or C99 (99 amino acids on the C-terminal of APP) were generated as previously described (38). The fragments were ligated into the expression vector pAG3.…”

“…Ranging from 1-38 to 1-55-We had previously employed the BRI2-A␤1-x fusion protein strategy to efficiently generate A␤1-40 and A␤1-42 in the late secretory pathway; additionally we had also shown that a BRI2-C99 (CTF␤) fusion protein efficiently generated C99 that could be subsequently processed by ␥-secretase to A␤ (38,40,48,49). Here we evaluated whether the BRI2 fusion protein strategy could be used to generate A␤ peptides spanning from 1-38 to 1-55 to examine their subsequent proteolyic processing.…”

Aβ-Degrading Proteases: Therapeutic Potential in Alzheimer Disease

“…Intriguingly, there is some evidence that extracellular pools of Ab may not be the most relevant to cognitive defects. For instance, overexpression of Ab42 exclusively in the extracellular space (using BRI-Ab42 fusion proteins [59]) led to the development of robust amyloid plaques [60], but failed to affect cognitive performance [61]. These intriguing findings could explain why therapies that target extracellular Ab, such as immunotherapies-have failed to affect cognitive decline.…”

Modeling familial British and Danish dementia

“…This system utilizes fusion constructs in which the sequence encoding the 23-amino-acid propeptide (Fig. 1a) at the C-terminus of BRI 2 is replaced with a sequence encoding either Ab40 or Ab42 (Lewis et al 2001). The system was used to generate AAV vectors to target expression of individual Ab peptides to the hippocampus of adult rats, allowing the examination of the role of each peptide in the pathology and cognitive deficits seen in AD models in the absence of AbPP over-expression (Lawlor et al 2007).…”