Hypersensitive mousetraps, α1-antitrypsin deficiency and dementia. (April 2002)

• Record Type: Journal Article
• Authors: Lomas, D. A.; Lourbakos, A.; Cumming, S.-A.; Belorgey, D.
• Is Part Of: Biochemical Society transactions. Volume 30:Number 2(2002)
• Page Start: 89
• Page End: 92
• Publication Date: 2002-04
• Subjects: inclusion bodies -- loop-sheet polymerization -- mutations -- neutrophil elastase -- serpins; Biochemistry -- Congresses; 572
• DOI: 10.1042/bst0300089
• Languages: English
• ISSNs: 0300-5127

Abstract

Abstract : α1 -Antitrypsin functions as a 'mousetrap' to inhibit its target proteinase, neutrophil elastase. The common severe Z deficiency variant (Glu 342 → Lys) destabilizes the mousetrap to allow a sequential protein-protein interaction between the reactive-centre loop of one molecule and β-sheet A of another. These loop-sheet polymers accumulate within hepatocytes to form inclusion bodies that are associated with juvenile cirrhosis and hepatocellular carcinoma. The lack of circulating protein predisposes the Z α1 -antitrypsin homozygote to emphysema. Loop-sheet polymerization is now recognized to underlie deficiency variants of other members of the serine proteinase inhibitor (serpin) superfamily, i.e. antithrombin, C1 esterase inhibitor and α1 -anti-chymotrypsin, which are associated with thrombosis, angio-oedema and emphysema respectively. Moreover, we have shown recently that the same process in a neuron-specific protein, neuroserpin, underlies a novel inclusion-body dementia, known as familial encephalopathy with neuroserpin inclusion bodies. Our understanding of the structural basis of polymerization has allowed the development of strategies to prevent the aberrant protein-protein interaction in vitro. This must now be achieved in vivo if we are to treat the associated clinical syndromes.