β-amyloid precursor protein mRNA is increased in... : NeuroReport (original) (raw)
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β-amyloid precursor protein mRNA is increased in inclusion-body myositis muscle
Sarkozi, Eva1; Askanas, Valerie1; Johnson, Steven A.2; Engel, W. King1; Alvarez, Renate B.1
1USC Neuromuscular Center, Department of Neurology, University of Southern California School of Medicine, 637 South Lucas Avenue, Los Angeles, CA 90017
2Andrus Gerontology Center, University of Southern California, University Park, Los Angeles, CA 90089, USA
Abstract
Vacuolated muscle fibers in muscle biopsies of 8 out of 8 inclusion body myositis (IBM) patients, including 2 hereditary patients, manifested increased mRNA for the β-amyloid precursor protein (βAPP) that contains Kunitz-type protease inhibitor motif. In affected fibers, increased βAPP-mRNA corresponded to abnormally accumulated βAPP immunoreactivity (including β-amyloid protein epitope). In normal human muscle fibers increased βAPP-mRNA was present only at the neuromuscular junctions. Our study (a) suggests that abnormally accumulated βAPP in IBM vacuolated fibers results, at least partly, from increased βAPP generation, and (b) provides the first demonstration of up-regulated βAPP-mRNA in pathologic human tissue other than brain of Alzheimer's disease and Down's syndrome.
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