The role of SPATA2 for inflammation and cell death

• Applicant: Privatdozent Dr. Ulrich Maurer
• Subject Area: Immunology ; Cell Biology
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 411119877

We have identified the protein SPATA2 as a novel member of the TNFR1 signalling complex. We found that SPATA2 recruits the deubiquitinase CYLD to TNFR1 complex I and thereby attenuates pro-inflammatory cytokine signalling, while on the other hand, SPATA2 promotes apoptosis and necroptosis induced by TNF. Thus, while a profound effect of SPATA2 on TNF signalling could be shown, a lot of work remains to be done to characterize the function of SPATA2, and the regulation of SPATA2 and its role in vivo are important outstanding questions. This proposal aims at characterizing the role of SPATA2 in vivo and to further understand the transcriptional and posttranslational regulation of SPATA2, and its role for TNF-induced cell death. We found high expression of SPATA2 in small intestine and colon as well as inducible expression of SPATA2 in intestinal organoids and we will explore the role of SPATA2, in comparison to CYLD, for a model of inflammatory bowel disease, employing spata2 and cyld knockout mice we have obtained.Our preliminary experiments demonstrated that the elevated expression of SPATA2 promotes TNF induced cell death, and we found that SPATA2 is cleaved by caspase-8. This raises the possibility that the cleavage of SPATA2 has a role for the prevention of necroptosis by caspase-8, and we will now characterize the functional implications of SPATA2 cleavage for cell death and pro-inflammatory cytokine signalling. We also observed that the phosphorylation of CYLD depends on the presence of SPATA2 and we will aim at identifying the responsible kinase, the phosphorylation site of CYLD and the functional implications. The role of SPATA2, in comparison to CYLD, for cell death will be explored on a genetic level. The deficiency of caspase-8 results in midgestation lethality due to necroptosis and we will breed caspase-8 deficient mice to spata2-/- or cyld-/- mice to explore the requirement of SPATA2 and CYLD for the developmental block in absence of caspase-8. Likewise, absence of TAK1 in endothelial tissues results in TNF-dependent midgestation lethality, and as we have observed that SPATA2 is required for TNF-induced cell death in absence of TAK1, we will test the requirement of SPATA2, but also CYLD, for the embryonic lethality of mice lacking this kinase, by crossing the respective knockout mice.

• DFG Programme: Research Grants