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Pathogenic amyloid beta-protein induces apoptosis in cultured human cerebrovascular smooth muscle cells
J Davis1, D H Cribbs, C W Cotman
1Department of Medicine, State University of New York, Stony Brook 11794-8153, USA.
Abstract:
The amyloid beta-protein (A beta) pathologically accumulates in cerebral vascular and senile plaque deposits in the brains of patients with Alzheimer's disease (AD) and related disorders including hereditary cerebral hemorrhage with amyloidosis Dutch type (HCHWA-D). The cerebrovascular deposits are accompanied by degeneration and eventual loss of smooth muscle cells in cerebral vessel wall. Similarly, we have shown that pathogenic forms of A beta cause cell death in cultured human cerebrovascular smooth muscle (HCSM) cells in vitro. Here we show that pathogenic A beta induces a number of structural changes in HCSM cells including shrinkage of cell bodies, retraction of processes, disruption of the intracellular actin network, and nuclear condensation and fragmentation. These changes were accompanied by a number of biochemical alterations in the cells shown by in situ end labeling of nuclear DNA, proteolytic breakdown of smooth muscle cell a actin, and proteolytic activation of the proteinase caspase 3. Together, these characteristics are consistent with an apoptotic mechanism of cell death in HCSM cells in response to pathogenic A beta.
Insights
Pathogenic amyloid beta-protein (A beta) causes Alzheimer's disease brain cell death. This study reveals A beta induces structural and biochemical changes in human cerebrovascular smooth muscle cells, indicating apoptosis.
Area of Science:
- Neuroscience
- Cell Biology
- Pathology
Background:
- Alzheimer's disease (AD) involves amyloid beta-protein (A beta) accumulation in brain vasculature and plaques.
- Cerebrovascular A beta deposits correlate with smooth muscle cell loss in cerebral vessels.
- Previous studies showed pathogenic A beta induces cell death in cultured human cerebrovascular smooth muscle (HCSM) cells.
Purpose of the Study:
- To investigate the specific cellular mechanisms by which pathogenic A beta induces cell death in HCSM cells.
- To characterize the structural and biochemical alterations in HCSM cells exposed to pathogenic A beta.
Main Methods:
- Cultured human cerebrovascular smooth muscle (HCSM) cells were treated with pathogenic A beta.
- Morphological changes were assessed (cell shrinkage, process retraction, nuclear condensation).
- Biochemical markers of apoptosis were analyzed (DNA fragmentation, actin breakdown, caspase 3 activation).
Main Results:
- Pathogenic A beta induced significant structural changes in HCSM cells, including cell shrinkage and nuclear fragmentation.
- Biochemical analysis confirmed DNA fragmentation and breakdown of smooth muscle actin.
- Proteolytic activation of caspase 3 was observed, a key indicator of apoptosis.
Conclusions:
- Pathogenic amyloid beta-protein triggers an apoptotic cell death pathway in human cerebrovascular smooth muscle cells.
- These findings provide insight into the cellular mechanisms underlying cerebrovascular degeneration in Alzheimer's disease and related disorders.
- Understanding A beta-induced apoptosis in vascular cells may inform future therapeutic strategies for AD.