OBJECTIVE: The metalloprotease ADAM17 (also called TACE) plays fundamental roles in homeostasis by shedding key signaling molecules from the cell surface. Although its importance for the immune system and epithelial tissues is well-documented, little is known about the role of ADAM17 in metabolic homeostasis. The purpose of this study was to determine the impact of ADAM17 expression, specifically in adipose tissues, on metabolic homeostasis. METHODS: We used histopathology, molecular, proteomic, transcriptomic, in vivo integrative physiological and ex vivo biochemical approaches to determine the impact of adipose tissue-specific deletion of ADAM17 upon adipocyte and whole organism metabolic physiology. RESULTS: ADAM17adipoq-creΔ/Δ mice exhibited a hypermetabolic phenotype characterized by elevated energy consumption and increased levels of adipocyte thermogenic gene expression. On a high fat diet, these mice were more thermogenic, while exhibiting elevated expression levels of genes associated with lipid oxidation and lipolysis. This hypermetabolic phenotype protected mutant mice from obesogenic challenge, limiting weight gain, hepatosteatosis and insulin resistance. Activation of beta-adrenoceptors by the neurotransmitter norepinephrine, a key regulator of adipocyte physiology, triggered the shedding of ADAM17 substrates, and regulated ADAM17 expression at the mRNA and protein levels, hence identifying a functional connection between thermogenic licensing and the regulation of ADAM17. Proteomic studies identified Semaphorin 4B (SEMA4B), as a novel ADAM17-shed adipokine, whose expression is regulated by physiological thermogenic cues, that acts to inhibit adipocyte differentiation and dampen thermogenic responses in adipocytes. Transcriptomic data showed that cleaved SEMA4B acts in an autocrine manner in brown adipocytes to repress the expression of genes involved in adipogenesis, thermogenesis, and lipid uptake, storage and catabolism. CONCLUSIONS: Our findings identify a novel ADAM17-dependent axis, regulated by beta-adrenoceptors and mediated by the ADAM17-cleaved form of SEMA4B, that modulates energy balance in adipocytes by inhibiting adipocyte differentiation, thermogenesis and lipid catabolism.

• Klíčová slova
• ADAM17/TACE, Adipose tissue, Beta-adrenoceptor signalling, Cold challenge, Metabolism, Obesity, Semaphorin4B Sema4b, Thermogenesis,
• MeSH
• adipokiny * metabolismus   MeSH
• beta-adrenergní receptory metabolismus   MeSH
• buněčná diferenciace MeSH
• hnědé tukové buňky metabolismus   MeSH
• lipidy MeSH
• myši MeSH
• proteomika MeSH
• semaforiny * genetika   metabolismus   MeSH
• termogeneze fyziologie   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adipokiny * MeSH
• beta-adrenergní receptory MeSH
• lipidy MeSH
• semaforiny * MeSH
• semaphorin 4B, mouse MeSH Prohlížeč

Several membrane-anchored signal mediators such as cytokines (e.g. TNFα) and growth factors are proteolytically shed from the cell surface by the metalloproteinase ADAM17, which, thus, has an essential role in inflammatory and developmental processes. The membrane proteins iRhom1 and iRhom2 are instrumental for the transport of ADAM17 to the cell surface and its regulation. However, the structure-function determinants of the iRhom-ADAM17 complex are poorly understood. We used AI-based modelling to gain insights into the structure-function relationship of this complex. We identified different regions in the iRhom homology domain (IRHD) that are differentially responsible for iRhom functions. We have supported the validity of the predicted structure-function determinants with several in vitro, ex vivo and in vivo approaches and demonstrated the regulatory role of the IRHD for iRhom-ADAM17 complex cohesion and forward trafficking. Overall, we provide mechanistic insights into the iRhom-ADAM17-mediated shedding event, which is at the centre of several important cytokine and growth factor pathways.

• Klíčová slova
• ADAM17, EGFR ligand release iRhom–ADAM17 complex structure, Ectodomain shedding, TNF signalling, iRhom, iRhom homology domain,
• MeSH
• buněčná membrána metabolismus   MeSH
• cytokiny metabolismus   MeSH
• membránové proteiny * metabolismus   MeSH
• modely strukturální MeSH
• protein ADAM17 metabolismus   MeSH
• transportní proteiny * genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cytokiny MeSH
• membránové proteiny * MeSH
• protein ADAM17 MeSH
• transportní proteiny * MeSH

Membrane-tethered signalling proteins such as TNFα and many EGF receptor ligands undergo shedding by the metalloproteinase ADAM17 to get released. The pseudoproteases iRhom1 and iRhom2 are important for the transport, maturation and activity of ADAM17. Yet, the structural and functional requirements to promote the transport of the iRhom-ADAM17 complex have not yet been thoroughly investigated. Utilising in silico and in vitro methods, we here map the conserved iRhom homology domain (IRHD) and provide first insights into its structure and function. By focusing on iRhom2, we identified different structural and functional factors within the IRHD. We found that the structural integrity of the IRHD is a key factor for ADAM17 binding. In addition, we identified a highly conserved motif within an unstructured region of the IRHD, that, when mutated, restricts the transport of the iRhom-ADAM17 complex through the secretory pathway in in vitro, ex vivo and in vivo systems and also increases the half-life of iRhom2 and ADAM17. Furthermore, the disruption of this IRHD motif was also reflected by changes in the yet undescribed interaction profile of iRhom2 with proteins involved in intracellular vesicle transport. Overall, we provide the first insights into the forward trafficking of iRhoms which is critical for TNFα and EGF receptor signalling.

• Klíčová slova
• ADAM17, Ectodomain shedding, Growth factors, TNF, iRhom, iRhom homology domain,
• MeSH
• aminokyselinové motivy MeSH
• buněčné linie MeSH
• epidermální růstové faktory metabolismus   MeSH
• lidé MeSH
• malá interferující RNA metabolismus   MeSH
• membránové proteiny genetika   metabolismus   MeSH
• mutageneze MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• poločas MeSH
• protein ADAM17 chemie   metabolismus   MeSH
• proteinové domény MeSH
• RNA interference MeSH
• signální transdukce MeSH
• TNF-alfa metabolismus   MeSH
• transport proteinů MeSH
• transportní proteiny antagonisté a inhibitory   genetika   metabolismus   MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• epidermální růstové faktory MeSH
• iRhom1 protein, mouse MeSH Prohlížeč
• iRhom2 protein, mouse MeSH Prohlížeč
• malá interferující RNA MeSH
• membránové proteiny MeSH
• protein ADAM17 MeSH
• TNF-alfa MeSH
• transportní proteiny MeSH