SPATA2 regulates inflammation and cell death independently of CYLD

Abstract: Pro-inflammatory signaling mediated by immune and cytokine receptors is crucial for the induction of adequate immune responses to eliminate invading pathogens. Tight regulation of these pathways is important to prevent pathologies or the onset of autoimmune or chronic inflammatory diseases. Upon immune receptor engagement, non-degradative ubiquitylation is an essential posttranslational modification (PTM), which allows the recruitment of kinases to activate pro-survival/inflammatory NF-κB and MAPK signaling. It is mediated mainly by E3 ubiquitin ligases such as cIAP1/2 and the linear ubiquitin assembly complex (LUBAC). Deubiquitinases (DUBs) like CYLD and OTULIN play critical roles for the regulation of pro-inflammatory signaling by removing K63- and M1-linked ubiquitin chains from receptor complexes, e.g., the tumor necrosis factor (TNF) receptor I (TNFR1). The adaptor protein SPATA2, which bridges the interaction of CYLD with LUBAC, mediates recruitment of CYLD to the TNFR1 signaling complex (TNFR1-SC). Whether SPATA2 exhibits other functions independently of CYLD is not known so far. Therefore, the aim of this study was to identify if SPATA2 and CYLD can function independently of each other.
It could be shown that homozygous deletion of SPATA2 and CYLD in mice resulted in perinatal lethality of the majority of double knockout (Cyld-/-Spata2-/-) offspring. Surviving Cyld-/-Spata2-/- animals were smaller than littermates, had a kinked tail and elevated marginal zone B cell numbers, indicating unrestricted NF-κB activation in the absence of both proteins. Combined loss of SPATA2 and CYLD in murine embryonic fibroblasts (MEF) and bone marrow-derived macrophages (BMDM) induced elevated pro-inflammatory gene expression and increased NF-κB and MAPK activation. Increased TNFR1-SC ubiquitylation in Cyld-/-Spata2-/- MEF in comparison to Cyld-/- or Spata2-/- cells. TNF-induced cell death was reduced in Cyld-/-Spata2-/- MEF as compared to single knockout cells, which was reversed after reconstitution of SPATA2 or CYLD. In addition to the PUB interacting motif (PIM), the zinc finger region (ZnF) of SPATA2 was identified as novel motif required for HOIP interaction. Furthermore, it was seen that the PIM and ZnF domain of SPATA2 are necessary to attenuate pro-inflammatory signaling in the absence of CYLD. SPATA2 counteracts LUBAC activity by displacing OTULIN from HOIP, thereby promoting auto-ubiquitylation of LUBAC. In consequence, increased pro-inflammatory signaling upon combined loss of SPATA2 and CYLD depends on the presence of OTULIN. As another finding, BMDM) generated from Cyld-/-Spata2-/- animals exhibited stronger priming and induction of the NLRP1b inflammasome. Additional deletion of caspase-1 resulted in increased survival of Cyld-/-Spata2-/- mice. Furthermore, it could be seen that SPATA2 is a crucial regulator of intestinal inflammation as combined loss of SPATA2 and CYLD led to villus blunting, increased pro-inflammatory cytokine expression in intestinal epithelial cells and developmental defects of intestinal organoids. Thus, this study revealed that SPATA2 and CYLD have mutually independent functions for regulating inflammatory responses and cell death induction

Angaben zum Objekt

• Standort: Deutsche Nationalbibliothek Frankfurt am Main
• Umfang: Online-Ressource
• Sprache: Englisch
• Anmerkungen: Universität Freiburg, Dissertation, 2023

Klassifikation und Themen

• Schlagwort: Signaltransduktion ; Apoptosis ; Tumor-Nekrose-Faktor ; Proteasom ; Ubiquitinierung ; Entzündung ; Zelltod

Beteiligte, Orts- und Zeitangaben

• Ereignis: Veröffentlichung
• (wo): Freiburg
• (wer): Universität
• (wann): 2023
• Urheber: Griewahn, Laura
• Beteiligte Personen und Organisationen: Maurer, Ulrich ; Häcker, Georg ; Groß, Olaf ; Albert-Ludwigs-Universität Freiburg. Institut für Molekulare Medizin und Zellforschung ; Albert-Ludwigs-Universität Freiburg. Fakultät für Biologie

Weitere Informationen

• DOI: 10.6094/UNIFR/233569
• URN: urn:nbn:de:bsz:25-freidok-2335694
• Rechteinformation: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Letzte Aktualisierung: 25.03.2025, 13:50 MEZ