Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.56 (insulin-degrading enzyme)
 737 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The deposition of amyloid beta-protein (A beta or beta A4) is a key feature of Alzheimer's disease. Most studies have focused on the generation of A beta, but little is known about the degradation of A beta. Recent reports suggest that insulin-degrading enzyme (IDE) and neutral endopeptidase (NEP) are involved in the extracellular degradation of A beta. To date, however, far less is known about the degradation of intracellular A beta. To elucidate the protease(s) responsible for the degradation of intracellular A beta, we investigated the effect of various protease inhibitors on A beta in two distinct intracellular pools (i.e., nonionic detergent-soluble and detergent-insoluble pools) in Chinese hamster ovary cells. Treatment with thiol and metal inhibitors resulted in the accumulation of intracellular A beta and oligomers in detergent-soluble and -insoluble fractions. The overexpression of thiol-metalloprotease IDE resulted in a marked reduction in levels of detergent-soluble intracellular A beta as well as extracellular A beta 40 and A beta 42. Moreover, intracellular A beta in the detergent-insoluble fraction extracted with 70% formic acid or 6 M guanidine hydrochloride decreased markedly in the cells overexpressing IDE. In contrast, expression of NEP degraded the A beta in the detergent-insoluble fraction markedly and partially degraded extracellular A beta 40 and A beta 42, but not intracellular soluble A beta. Thiorphan, an inhibitor of NEP, accumulated, albeit to a lesser extent, in insoluble A beta but not in soluble A beta. Thus, IDE appears to degrade intracellular A beta more effectively than does NEP in both the detergent-soluble and -insoluble fractions.
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PMID:Differential effects of proteases involved in intracellular degradation of amyloid beta-protein between detergent-soluble and -insoluble pools in CHO-695 cells. 1180 7

The progressive cerebral deposition of a 40-42 residues amyloid beta-peptide (Abeta) is regarded as a major factor in the onset of the Alzheimer's disease. It has recently been shown that Abeta(1-40) is cleaved by Escherichia coli pitrilysin, a homologue of insulysin, at a specific site. To facilitate the studies on a recognition mechanism of Abeta by pitrilysin, an overproduction system of Abeta(1-40) as a fusion protein with E. coli RNase HI was constructed. This fusion protein was designed such that an Abeta(1-40) derivative, Abeta(1-40)*, in which Lys16 and Lys28 of Abeta(1-40) are simultaneously replaced by Ala, is attached to the C-terminus of E. coli RNase HI and Abeta(1-40)* is separated from RNase HI upon cleavage with lysyl endopeptidase. The fusion protein was overproduced in E. coli in inclusion bodies, solubilized and purified in the presence of guanidine hydrochloride, and cleaved by lysyl endopeptidase. Abeta(1-40)* was purified from the resultant peptide fragments by reverse-phase HPLC. Measurement of the far-UV CD spectra suggests that Abeta(1-40)* is conformationally similar to Abeta(1-40). However, the thioflavin T binding assay suggests that Abeta(1-40)* is more amyloidogenic than Abeta(1-40). Nevertheless, Abeta(1-40)* was cleaved by pitrilysin at the site identical to that in Abeta(1-40).
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PMID:Amyloidogenecity and pitrilysin sensitivity of a lysine-free derivative of amyloid beta-peptide cleaved from a recombinant fusion protein. 1623 26