M-CALPAIN (CALCIUM-ACTIVATED NEUTRAL PROTEINASE) IN ALZHEIMERS-DISEASE BRAINS

An antibody specific for the calpain isoform m-calpain was used to res olve conflicting results from several studies on the possible role of m-calpain in the pathogenesis of Alzheimer's disease (AD). Levels of t he enzyme in both cytosolic and membranous fractions of brain tissue w ere determined by Western blot analysis. We also demonstrated changes in m-calpain molecules in AD brains using high-resolution 2D gel elect rophoresis (2DE). The levels of the m-calpain isoform detected in the cytosolic fraction were significantly increased in AD brains when comp ared with the levels in controls. On 2DE, m-calpain molecules resolved into eight main spots. These spots were detected in AD brains as well as in control brains, suggesting that the calpain molecule was not qu alitatively changed in AD. Quantitative analysis of the m-calpain spot s on 2DE, on the other hand, indicated that the ratio of the intensity of four protein spots in the acidic region to that of the total spots was increased in AD brains. (C) 1998 Elsevier Science Ireland Ltd. Al l rights reserved.