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Presenilins upregulate functional K+ channel currents in mammalian cells
1Department of Molecular Biology and Pharmacology, Washington University Medical School, St Louis, Missouri 63110, USA.
Neurobiology of Disease
|July 17, 1998
Summary
Presenilin mutations linked to Alzheimer's disease may affect brain cell function by altering potassium (K+) channel activity. These proteins appear to regulate K+ channels, potentially explaining cognitive decline in Alzheimer's disease patients.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Presenilin 1 (PS-1) and presenilin 2 (PS-2) mutations are implicated in early-onset Alzheimer's disease.
- The precise functions of presenilins and their role in Alzheimer's pathogenesis remain unclear.
Purpose of the Study:
- To investigate the functional role of presenilins in regulating ion channel activity.
- To explore the impact of PS-1 and PS-2 on potassium (K+) currents in cellular models.
Main Methods:
- Transfection of HEK-293 cells and neonatal rat ventricular myocytes with wild-type and mutant PS-1/PS-2.
- Measurement of outward K+ current densities using electrophysiology.
- Western blot analysis to assess protein expression levels.
Main Results:
- Expression of wild-type PS-1 and PS-2 increased outward K+ current densities in HEK-293 cells.
- Full-length PS-1 and PS-2, not processed fragments, were associated with increased K+ currents.
- A non-proteolytically processed PS-1 mutant (deltaex9/PS-1) also increased K+ currents, while a missense mutant (G209V) did not.
Conclusions:
- Presenilins likely upregulate K+ channel expression rather than forming channels themselves.
- PS-1 and PS-2 may associate with or influence the synthesis/transport of K+ channel subunits.
- Dysregulation of neuronal K+ channel expression by presenilins could contribute to Alzheimer's disease pathology.