Constitutive shedding of the amyloid precursor protein ectodomain is up-regulated by tumour necrosis factor-α converting enzyme

Abstract

The amyloid precursor protein (APP) of Alzheimer's disease is a transmembrane protein that is cleaved within its extracellular domain, liberating a soluble N-terminal fragment (sAPP alpha). Putative mediators of this process include three members of the ADAM (a disintegrin and metalloprotease) family, ADAM9, ADAM10 and ADAM17/TACE (tumour necrosis factor-alpha converting enzyme). Tumour necrosis factor-alpha protease inhibitor (TAPI-1), an inhibitor of ADAMs, reduced constitutive and muscarinic receptor-stimulated sAPP alpha release in HEK-293 cells stably expressing M3 muscarinic receptors. However, the former was less sensitive to TAPI-1 (IC(50)=8.09 microM) than the latter (IC(50)=3.61 microM), suggesting that these processes may be mediated by different metalloproteases. Constitutive sAPP alpha release was increased several-fold in cells transiently transfected with TACE, and this increase was proportional to TACE expression. In contrast, muscarinic-receptor-activated sAPP alpha release was not altered in TACE transfectants. TACE-dependent constitutive release of co-transfected APP(695) was inhibited by TAPI-1 with an IC(50) of 0.92 microm, a value significantly lower than the IC(50)s for inhibition of either constitutive or receptor-regulated sAPP alpha shedding mediated by endogenous secretases. The results indicate that TACE is capable of catalysing constitutive alpha-secretory cleavage of APP, but it is likely that additional members of the ADAM family mediate endogenous constitutive and receptor-coupled release of sAPP alpha in HEK-293 cells.

Collagen type I selectively activates ectodomain shedding of the discoidin domain receptor 1: Involvement of Src tyrosine kinase

“…6). This was similar to the concentration of TAPI-1 previously found to inhibit receptor-coupled release of the APP ectodomain [Slack et al, 2001]. DDR1b shedding was also blocked by TIMP-3, but not TIMP-1 or TIMP-2 (Fig.…”

“…TIMP-3 inhibits both ADAM10 and TACE, whereas TIMP-1 inhibits ADAM10 but not TACE [Amour et al, 1998;Amour et al, 2000]. Both these ADAMs are expressed in HEK cells [Slack et al, 2001], and our results could suggest that collagen-dependent DDR1 shedding is mediated either by TACE alone, which would account for the resistance of the response to TIMP-1, or by both TACE and ADAM10. The results, however, do not rule out the possible involvement of other metalloproteinases in the response, including, for example, ADAM12, or ADAM19, both of which may act as sheddases [Arribas and Borroto, 2002] and are inhibited by TIMP-3 [Baker et al, 2002].…”

“…Conditioned medium and cells were collected and processed for immunoblotting as previously described [Slack et al, 2001]. Samples were size-fractionated by SDS-PAGE and transferred to polyvinylidene difluoride membranes.. Antibodies to the N-and C-terminus of DDR1 and to E-cadherin, and anti-phosphotyrosine antibodies (clone PY99) were obtained from Santa Cruz Biotechnology (Santa Cruz CA).…”

Tumor necrosis factor α-converting enzyme mediates MUC5AC mucin expression in cultured human airway epithelial cells

“…However, the mechanism by which these stimuli cause EGFR phosphorylation was unknown. To investigate this mechanism, we used PMA, a widely used stimulus known to increase ectodomain shedding of various cell surface molecules, [e.g., TNF-␣, TGF-␣ (26), p75TNF receptor (12), L-selectin (12), and ␤-amyloid precursor protein (27)] and to cause EGFR phosphorylation. We show that PMA increases MUC5AC expression dose-and time-dependently (Fig.…”

Down-Regulation of the Met Receptor Tyrosine Kinase by Presenilin-dependent Regulated Intramembrane Proteolysis

“…We checked the effect of metalloprotease inhibitors on generation of Met fragments. Inhibition of zinc metalloprotease activity by the broad-spectrum inhibitor GM6001 (Galardy et al, 1994) or the ADAM inhibitor TAPI-1 (Slack et al, 2001) prevented stabilization of both Met-ICD and Met-CTF induced in MDCK cells by E compound and lactacystin ( Figure 3A). Similar inhibition of Met-CTF generation by TAPI-1 was observed in human mammary epithelial cells MCF10A (Supplementary Figure S2).…”