Identification of Molecular Determinants in iRhoms1 and 2 That Contribute to the Substrate Selectivity of Stimulated ADAM17

Abstract

The metalloprotease ADAM17 is a key regulator of the TNFα, IL-6R and EGFR signaling pathways. The maturation and function of ADAM17 is controlled by the seven-membrane-spanning proteins iRhoms1 and 2. The functional properties of the ADAM17/iRhom1 and ADAM17/iRhom2 complexes differ, in that stimulated shedding of most ADAM17 substrates tested to date can be supported by iRhom2, whereas iRhom1 can only support stimulated shedding of very few ADAM17 substrates, such as TGFα. The first transmembrane domain (TMD1) of iRhom2 and the sole TMD of ADAM17 are important for the stimulated shedding of ADAM17 substrates by iRhom2. However, little is currently known about how the iRhoms interact with different substrates to control their stimulated shedding by ADAM17. To provide new insights into this topic, we tested how various chimeras between iRhom1 and iRhom2 affect the stimulated processing of the EGFR-ligands TGFα (iRhom1- or 2-dependent) and EREG (iRhom2-selective) by ADAM17. This uncovered an important role for the TMD7 of the iRhoms in determining their substrate selectivity. Computational methods utilized to characterize the iRhom1/2/substrate interactions suggest that the substrate selectivity is determined, at least in part, by a distinct accessibility of the substrate cleavage site to stimulated ADAM17. These studies not only provide new insights into why the substrate selectivity of stimulated iRhom2/ADAM17 differs from that of iRhom1/ADAM17, but also suggest new approaches for targeting the release of specific ADAM17 substrates.

FGFR2 mutations promote endometrial cancer progression through dual engagement of EGFR and Notch signalling pathways

“… 82 ADAM10 and ADAM17 are part of distinct multiprotein/substrate complexes. 82 , 83 In addition, previous studies demonstrated that proteases can modulate the activity of other proteases through prodomain cleavage. 84 Therefore, it is also possible that aberrant complex formation in FGFR2 ‐mutant ECs leads to the direct interaction of ADAM17 with ADAM10 and the subsequent modification of its proteolytic activity.…”

“…Although the molecular mechanisms of this crosstalk are not known, it is possible that the aberrant activation of ADAM17/EGFR‐mediated downstream signalling pathways in FGFR2 ‐mutant ECs leads to an increased proteolytic activity of ADAM10 or alternatively increased accessibility to its substrate 82 . ADAM10 and ADAM17 are part of distinct multiprotein/substrate complexes 82,83 . In addition, previous studies demonstrated that proteases can modulate the activity of other proteases through prodomain cleavage 84 .…”

Peptidoglycan fromBacillus anthracis InhibitsHuman Macrophage Efferocytosis in Part by Reducing Cell Surface Expression of MERTK and TIM-3

“…Interestingly, we did not observe changes in the levels of soluble TYRO3, AXL, MERTK or TIM-3, suggesting that B. anthracis PGN induces selective substrate cleavage and/or alternative regulation beyond cell-surface expression. Work by Maretzky et al have shown that ADAM17 can cleave different substrates when in the presence of rhomboid proteins 1 or 2 (iRhom1, iRhom2), demonstrating that when complexed together, iRhom proteins can modify ADAM17 substrate specificity 62, 63 . To the best of our knowledge substrate specificity as a mechanism of receptor regulation has yet to be shown for the TYRO, AXL, MERTK (TAM) family.…”

The protease ADAM17 at the crossroads of disease: revisiting its significance in inflammation, cancer, and beyond

“…On the contrary, mEFs lacking iRhom1 showed reduced shedding of TGFα [27]. Recently, it has been proposed that this iRhom‐mediated substrate selectivity of ADAM17 could be explained partly by the differential presentation by iRhom1 and iRhom2 of substrate cleavage sites to active ADAM17 [101]. Notably, ADAM17 substrate selectivity may also be regulated via certain signaling pathways in response to ADAM17 activity inducers, and irrespective of enhanced ADAM17 protease activity.…”