Cleavage of Annexin A1 by ADAM10 during Secondary Necrosis Generates a Monocytic “Find-Me” Signal

Abstract

Annexin A1 is an intracellular calcium/phospholipid-binding protein that is involved in membrane organization and the regulation of the immune system. It has been attributed an anti-inflammatory role at various control levels, and recently we could show that annexin A1 externalization during secondary necrosis provides an important fail-safe mechanism counteracting inflammatory responses when the timely clearance of apoptotic cells has failed. As such, annexin A1 promotes the engulfment of dying cells and dampens the postphagocytic production of proinflammatory cytokines. In our current follow-up study, we report that exposure of annexin A1 during secondary necrosis coincided with proteolytic processing within its unique N-terminal domain by ADAM10. Most importantly, we demonstrate that the released peptide and culture supernatants of secondary necrotic, annexin A1-externalizing cells induced chemoattraction of monocytes, which was clearly reduced in annexin A1- or ADAM10-knockdown cells. Thus, altogether our findings indicate that annexin A1 externalization and its proteolytic processing into a chemotactic peptide represent final events during apoptosis, which after the transition to secondary necrosis contribute to the recruitment of monocytes and the prevention of inflammation.

Proresolving and Tissue-Protective Actions of Annexin A1–Based Cleavage-Resistant Peptides Are Mediated by Formyl Peptide Receptor 2/Lipoxin A4 Receptor

“…The AnxA1 N-terminal region is the site of attack by many proteases that may either lead to the inactivation of the protein (15) or release of peptides endowed with distinct bioactions to the parent protein (32). Thus, we assessed cleavage of AnxA1 2-50 by human PR3 and HNE, two enzymes associated with pathogenesis in vascular (33) and lung (34) diseases, but also abundant in inflammatory exudates (15,16).…”

Serum-Derived Plasminogen Is Activated by Apoptotic Cells and Promotes Their Phagocytic Clearance

“…THP-1 cells were differentiated into macrophages with 10 nM PMA (Sigma-Aldrich) for 2.5 d, irradiated with 10 mJ/cm 2 UV-C to undergo apoptosis, or heated to 58˚C for 20 min to induce necrosis, respectively (7,8). Plasminogen, plasmin, thrombin, and plasminogen activator inhibitor-1 (PAI-1) were purchased from American Diagnostica (Heidelberg, Germany), plasminogen FITC was from Biomac (Leipzig, Germany), and plasmin-Cy2 was prepared with the Cy2-labeling kit (GE Healthcare), according to the manufacturer's instructions.…”

Sladek Z, Rysanek D: CD14 expression, apoptosis and necrosis in resident and inflammatory macrophages from virgin bovine mammary gland

“…This has physiological significance during inflammation, since secondary necrosis can lead to the release of chemotactic peptides, which, in turn, may induce recruitment of monocytes into inflamed tissue. Moreover, proteins released from necrotic cells can opsonise apoptotic cells and thus facilitate their phagocytic uptake, which contributes to the resolution of inflammation (Blume et al 2009;Blume et al 2012).…”