title: Increased spectrin proteolysis in fibroblasts from aged and Alzheimer donors.
abstract: Since calcium homeostasis is altered in cultured skin fibroblasts from aged and Alzheimer donors, the present study examined the degradation of spectrin, a substrate of the calcium dependent protease calpain. Spectrin proteolysis was estimated as the percentage of spectrin breakdown products (e.g., 150 + 155 kDa bands) per total spectrin immunoreactivity. In the baseline condition (e.g., unstimulated fibroblasts), spectrin breakdown was 53% greater in cells from aged donors when compared to cells from either young or Alzheimer donors. Compared to unstimulated cells, serum increased spectrin breakdown in cells from aged (22.4%) or Alzheimer (92.1%) donors but was ineffective in cells from young donors. Thus, when compared to young donors (100%), serum stimulation increased spectrin proteolysis by 183.9% (aged) or 231.7% (Alzheimer) after serum stimulation. Treatment of unstimulated cells with carbonyl cyanide 4-trifluoromethoxy-phenylhydrazone (FCCP), an uncoupler of mitochondrial function, increased spectrin degradation by 360.6% (young), 242.4% (aged) or 239.7% (Alzheimer) when compared to unstimulated cells of the same group. The combination of FCCP and serum stimulation enhanced spectrin breakdown in cells from aged (123.6%) and Alzheimer (154.0%) donors when compared to young cells (100%). Thus, changes in the regulation of calcium dependent proteases may contribute to decreased cell spreading and may play a role in the altered cytoskeletal dynamics characteristic of Alzheimer's disease.
authors.affiliation: Department of Psychobiology, University of California, Irvine 92717.
authors.forename: C
authors.initials: C
authors.lastname: Peterson
authors.forename: P
authors.initials: P
authors.lastname: Vanderklish
authors.forename: P
authors.initials: P
authors.lastname: Seubert
authors.forename: C
authors.initials: C
authors.lastname: Cotman
authors.forename: G
authors.initials: G
authors.lastname: Lynch
mesh_terms: D000368:Aged; D000375:Aging / Q000378:metabolism; D000544:Alzheimer Disease / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002154:Calpain / Q000378:metabolism; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000187:drug effects; D004586:Electrophoresis; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D012867:Skin / Q000166:cytology; D013049:Spectrin / Q000378:metabolism*
chemical_list: D002135:Calcium-Binding Proteins; D013049:Spectrin; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; C033668:calpastatin; D002154:Calpain