ADAM17 deficiency by mature neutrophils has differential effects on L-selectin shedding

Abstract

L-selectin directs neutrophils to sites of inflammation, and upon their activation, surface expression of the receptor is rapidly down-regulated by ectodomain shedding. Tumor necrosis factor-␣-converting enzyme (TACE, or ADAM17) is a sheddase of L-selectin; however, Adam17 gene targeting (ADAM17 ⌬Zn/⌬Zn ) in mice is perinatal lethal and its role in L-selectin shedding by mature neutrophils has not been determined. This was addressed here by using radiation-chimeric mice reconstituted with ADAM17 ⌬Zn/⌬Zn fetal liver cells. ADAM17-deficient neutrophils, monocytes, and lymphocytes failed to shed L-selectin in response to PMA, as did neutrophils infiltrating the inflamed peritoneum. In addition, the absence of functional ADAM17 resulted in significantly increased levels of L-selectin surface expression by peripheral-blood leukocytes, indicating the sheddase also plays a role in the constitutive cleavage of L-selectin. Interestingly, not all manners of L-selectin turnover required ADAM17. Plasma L-selectin levels were similar between ADAM17 ⌬Zn/⌬Zn -chimeric and control mice, as was the shedding of L-selectin by neutrophils undergoing spontaneous apoptosis. The latter process, however, was diminished by a metalloprotease inhibitor, indicating the role of a sheddase other than ADAM17. Together, our data reveal that L-selectin's surface density on neutrophils is regulated by ADAM17, but homeostatic L-selectin cleavage is not. IntroductionL-selectin (CD62L) is a type-1 transmembrane protein that is constitutively and uniformly expressed by neutrophils. It plays a critical role in directing these cells to sites of inflammation. L-selectin's adhesive role is diverse and includes facilitating direct and indirect neutrophil tethering along the vascular wall. 1 The latter process both accelerates and prolongs their accumulation. [2][3][4][5] Consistent with L-selectin's broad role in directing leukocyte accumulation, it is tightly regulated. This includes a rapid and efficient down-regulation from the surface of neutrophils upon their activation by various stimuli, with virtually all of the L-selectin molecules being released by a proteolytic process. 6 In addition to neutrophil activation, L-selectin shedding also occurs by these cells upon induced and spontaneous apoptosis. 7 The cleavage of L-selectin takes place proximal to the cell membrane, releasing an intact ectodomain fragment. 8,9 The soluble ectodomain portion of L-selectin is detected in the blood plasma, demonstrating that L-selectin shedding is a physiologic process. The functional relevance of L-selectin shedding is not yet fully understood. Studies involving gene-targeted mice expressing noncleavable L-selectin indicate that ectodomain shedding regulates surface L-selectin density, and this affects the efficiency of leukocyte adhesion and migration. 20 Homeostatic L-selectin cleavage accounts for high levels of the receptor in the plasma of healthy individuals and mice relative to other leukocyte membrane proteins, 10,11 and perhaps this process maintains an...

NK cell CD16 surface expression and function is regulated by a disintegrin and metalloprotease-17 (ADAM17)

“…Here we demonstrate that ADAM17, which leads to cleavage of CD62L in lymphocytes and neutrophils, 21 also performs this function in NK cells. In murine models of inflammation or bone marrow transplantation, NK cells home to lymph nodes and other Figure 5.…”

“…ADAM17 has been shown to mediate the shedding of CD62L, 21 as well as various other molecules. 31 Thus, we hypothesized that ADAM17 may be an important effector protease to regulate the surface density of CD16 and CD62L in NK cells.…”

“…17 ADAM17 is well characterized in neutrophils where it cleaves various effector molecules, including TNF-a, TNF receptor I, and TNF receptor II. [18][19][20] ADAM17 also cleaves CD62L (L-selectin), 21 a cell adhesion molecule expressed by most leukocyte subsets. 22 In the current study, we evaluated the expression and function of ADAM17 in human NK cells where it affects the activation-induced decrease in surface expression and function of CD16.…”

iRhoms 1 and 2 are essential upstream regulators of ADAM17-dependent EGFR signaling

“…S2B). Because iRhom2 is required for the maturation and function of ADAM17 in myeloid cells, we isolated CD45 high leukocytes from the brain to assess the function of ADAM17 by measuring the phorbol ester (phorbol 12-myristate 13-acetate; PMA)-stimulated shedding of CD62L (L-selectin) (31). We found that the PMAstimulated down-regulation of CD62L was comparable in wild-type and iR1 −/− brain leukocytes ( Fig.…”

Acidic Mammalian Chitinase Is Secreted via an ADAM17/Epidermal Growth Factor Receptor-dependent Pathway and Stimulates Chemokine Production by Pulmonary Epithelial Cells

“…ADAM17 acts as a sheddase where it processes and thereby regulates a variety of mediators and receptors, including EGFR transactivation (14), ectodomain shedding of TNF-␣ and TNFI and TNFII (TNF receptors I and II, respectively) (32), platelet glycoproteins (33), neurotrophin receptors (34), L-selectin (35), angiotensin-converting enzyme-2 (36), and fractalkine (37). ADAM17 activity in pulmonary epithelial cells has been reported to be induced by IL-13 (19,30), and TACE/ADAM17 processing of EGFR ligands has been found to play a critical role in IL-13-induced airway responses and proliferation of epithelial cells (19,30).…”