title: Mammalian iRhoms have distinct physiological functions including an essential role in TACE regulation.
abstract: Loss of iRhom2, a catalytically inactive rhomboid-like protein, blocks maturation of TACE/ADAM17 in macrophages, resulting in defective shedding of the cytokine tumor necrosis factor. Apart from the resulting inflammatory defects, iRhom2-null mice appear normal: they do not show the several defects seen in TACE knockouts, suggesting that TACE maturation is independent of iRhom2 in cells other than macrophages. Here we show that the physiological role of iRhoms is much broader. iRhom1 knockout mice die within 6 weeks of birth. They show a severe phenotype, with defects in several tissues including highly penetrant brain haemorrhages. The non-overlapping phenotypes imply that iRhom 1 and 2 have distinct physiological roles, although at a cellular level both promote the maturation of TACE (but not other ADAM proteases). Both iRhoms are co-expressed in many contexts where TACE acts. We conclude that all TACE activity, constitutive and regulated, requires iRhom function. iRhoms are therefore essential and specific regulators of TACE activity, but our evidence also implies that they must have additional physiologically important clients.
authors: MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
authors: Yonka
authors: Y
authors: Christova
authors: Colin
authors: C
authors: Adrain
authors: Paul
authors: P
authors: Bambrough
authors: Ashraf
authors: A
authors: Ibrahim
authors: Matthew
authors: M
authors: Freeman
mesh_terms: D051722:ADAM Proteins / Q000235:genetics / Q000378:metabolism*; D000072198:ADAM17 Protein; D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins; D051379:Mice; D018345:Mice, Knockout; D010641:Phenotype
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; C588247:iRhom1 protein, mouse; C569468:iRhom2 protein, mouse; D051722:ADAM Proteins; D000072198:ADAM17 Protein; C000606463:Adam17 protein, mouse
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