Activation of cell-surface proteases promotes necroptosis, inflammation and cell migration

Abstract

Necroptosis is a programmed, caspase-independent cell death that is morphologically similar to necrosis. TNF-induced necroptosis is mediated by receptor-interacting protein kinases, RIP1 and RIP3, and the mixed lineage kinase domain-like (MLKL). After being phosphorylated by RIP3, MLKL is translocated to the plasma membrane and mediates necroptosis. However, the execution of necroptosis and its role in inflammation and other cellular responses remain largely elusive. In this study, we report that MLKL-mediated activation of cell-surface proteases of the a disintegrin and metalloprotease (ADAM) family promotes necroptosis, inflammation and cell migration. ADAMs are specifically activated at the early stage of necroptosis when MLKL is phosphorylated and translocated to the cell plasma membrane. Activation of ADAMs induces ectodomain shedding of diverse cell-surface proteins including adhesion molecules, receptors, growth factors and cytokines. Importantly, the shedding of cell-surface proteins disrupts cell adhesion and accelerates necroptosis, while the soluble fragments of the cleaved proteins trigger the inflammatory responses. We also demonstrate that the shedding of E-cadherin ectodomain from necroptotic cells promotes cell migration. Thus, our study provides a novel mechanism of necroptosis-induced inflammation and new insights into the physiological and pathological functions of this unique form of cell death.

Nr CAM is a marker for substrate‐selective activation of ADAM 10 in Alzheimer's disease

“…This yielded 8 proteins (SERPINA7, PTPRS, CFHR1, B4GALT1, ST6GAL2, BCAM, GDA, and KLK11) being down‐regulated and 6 proteins (DCD, FABP5, PDCD6, TMSB4X, CSPG4, and CST6) being up‐regulated (Fig , Table ). Surprisingly, only one previously known ADAM10 substrate, CSPG4/NG2, which is expressed in oligodendrocyte precursor cells (Sakry et al , ), was found among the proteins with increased levels (Fig ), while over 50 known ADAM10 substrates () did not show significant changes, including NrCAM, thus confirming the Western blot results from Fig C and D. Three additional ADAM10 substrates, ST6GAL2 (Kuhn et al , ), BCAM (Cai et al , ), and PTPRS (Kuhn et al , ), even showed a lower abundance than in the placebo group (see also Table ), clearly showing that acitretin did not increase the shedding of all ADAM10 substrates. Additionally, it is important to note that the extent of the changes was mild for the one substrate with increased (22%) and the three substrates with decreased (up to 40%) ADAM10 cleavage products.…”

“…, while over 50 known ADAM10 substrates (Dataset EV1) did not show significant changes, including NrCAM, thus confirming the Western blot results fromFig 4C andD. Three additional ADAM10 substrates, ST6GAL2, BCAM(Cai et al, 2016), and PTPRS, even showed a lower abundance than in the placebo group (see also Table 1), clearly showing that acitretin did not increase the shedding of all ADAM10 substrates.…”

Necroptotic cell death in anti‐cancer therapy

“…It is conceivable that necroptotic endothelial cells, by releasing DAMPs and cytokines/chemokines, can enhance the migration of tumor cells through the endothelial barrier. In this regard, it has been shown that the E‐cadherin ectodomain shed by necroptotic cells promotes cell migration and invasion . Notably, elevated serum soluble E‐cadherin in different cancers promotes tumor growth and metastasis …”

To the edge of cell death and back

“…Furthermore, MLKL activation can also trigger the cleavage and shedding of several cell surface proteins (e.g., ectodomain), mediated by a family of cell surface proteases named ‘a disintegrin and metalloprotease’ (ADAM). More than 100 ADAM substrates have been identified to date, which may explain why the complex of p‐MLKL and ADAMs is able to promote inflammation, cell migration, and invasion . Taken together, even following resuscitation, necroptotic cells may engage these mechanisms to extend their biological consequences.…”