# MOLECULAR CELL BIOLOGY OF ALZHEIMER AMYLOIDOGENESIS

> **NIH NIH R01** · WEILL MEDICAL COLL OF CORNELL UNIV · 1992 · $169,471

## Abstract

Alzheimer's disease is characterized by clinical dementia in association
with pathologic alterations in brain proteins.  Structural lesions include
extracellular beta/A4-amyloid deposits.  Beta/A4-amyloid is derived through
proteolysis of a large, transmembrane precursor, the beta/A4-amyloid
precursor protein (APP).  Mutations in the coding sequence of APP are
associated with familial cerebral amyloidoses, pointing to the importance
of APP in the pathogenesis of amyloidosis.  The association of different
APP-mutation genotypes with the cerebral amyloidosis phenotype strongly
suggests that alternative amyloidogenic proteolysis may be a final common
pathway in both familial and sporadic cerebral amyloidotic diseases,
including Alzheimer's disease.

A standard pathway for proteolysis of about 30% of APP molecules (in PC-12
cells) cleaves within the beta/A44- amyloid domain, precluding amyloid
formation.  The generation of beta/A4-amyloid must therefore occur via an
alternative proteolytic pathway.  Evidence for the existence of alternative
pathways has emerged from several laboratories, in studies of human
cerebral vessels, brain, and cells in continuous culture.  Cell culture
systems which generate microheterogeneous proteolysis of APP include the
rat PC-12 line (under conditions of supraphysiological protein
phosphorylation), the monkey fibroblast (following overexpression of human
APP in recombinant vaccinia virus), the human APP-transfected human 293
cell, and the recombinant human APP-baculovirus infected Sf9 cell.  The Sf9
system is particularly attractive because of the extraordinarily high-level
expression of recombinant protein, providing convenience for purification
and sequencing of species of interest.  Sf9 cells faithfully recapitulate
many of the biological properties of mammalian cells.  When human APP is
expressed in Sf9 cells, a portion of APP molecules is cleaved in a position
exactly identical to the major cleavage site for proteolyzing APP in human
cells, thus providing validity to the use of the Sf9 cell as a model system
for APP proteolysis.

At high multiplicities-of-infection, in addition to the cleavage of APP at
this major conserved site (which generates a 14-15 Kda carboxyl-terminal
fragment), Sf9 cells produce a discrete and limited number of other APP
carboxyl-terminal fragments, including species of 16-, 17- and 25-Kda.  By
antigenic analysis, the 17-Kda species has been demonstrated to incorporate
amino-terminal epitopes of the beta/A4-amyloid domain and is thus a
putative amyloidogenic fragment.  While there is mounting immunochemical
evidence for such putative amyloidogenic fragments, direct protein
sequencing of such a species has not been achieved, and is the primary goal
of this proposal, using the baculoviral/Sf9 expression system.  In
addition, putative amyloidogenic mutant APP molecules (from familial
cerebral amyloidoses) will be overexpressed in baculoviruses, and their
proteolytic fragments characterized, pu...

## Key facts

- **NIH application ID:** 3123433
- **Project number:** 1R01AG011508-01
- **Recipient organization:** WEILL MEDICAL COLL OF CORNELL UNIV
- **SAM.gov UEI:** YNT8TCJH8FQ8
- **Principal Investigator:** SAMUEL E. GANDY
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1992
- **Award amount:** $169,471
- **Award type:** 1
- **Project period:** 1992-09-20 → 1995-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3123433

## Citation

> US National Institutes of Health, RePORTER application 3123433, MOLECULAR CELL BIOLOGY OF ALZHEIMER AMYLOIDOGENESIS (1R01AG011508-01). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3123433. Licensed CC0.

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