PMID: 8987819Dec 15, 1996Paper

Matrix metalloproteinase-9 (MMP-9) is synthesized in neurons of the human hippocampus and is capable of degrading the amyloid-beta peptide (1-40)

The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
J R BackstromZ A Tökés

Abstract

We reported earlier that the levels of Ca2+-dependent metalloproteinases are increased in Alzheimer's disease (AD) specimens, relative to control specimens. Here we show that these enzymes are forms of the matrix metalloproteinase MMP-9 (EC3.4.24. 35) and are expressed in the human hippocampus. Affinity-purified antibodies to MMP-9 labeled pyramidal neurons, but not granular neurons or glial cells. MMP-9 mRNA is expressed in pyramidal neurons, as determined with digoxigenin-labeled MMP-9 riboprobes, and the presence of this mRNA is confirmed with reverse transcriptase PCR. The cellular distribution of MMP-9 is altered in AD because 76% of the total 100 kDa enzyme activity is found in the soluble fraction of control specimens, whereas only 51% is detectable in the same fraction from AD specimens. The accumulated 100 kDa enzyme from AD brain is latent and can be converted to an active form with aminophenylmercuric acetate. MMP-9 also is detected in close proximity to extracellular amyloid plaques. Because a major constituent of plaques is the 4 kDa beta-amyloid peptide, synthetic Abeta1-40 was incubated with activated MMP-9. The enzyme cleaves the peptide at several sites, predominantly at Leu34-Met35 within the membrane-spanning...Continue Reading

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