Single cell RNA-seq of intestine from E18.5 Mlkl -/- and Casp8 C362A/C362A Mlkl -/- embryos

ABSTRACT: Caspase-8 is a protease with both pro-death and pro-survival functions: it is required for apoptosis induced by death receptors such as TNFR1 (tumour necrosis factor receptor 1), and it has a critical role in suppressing necroptosis mediated by the kinase RIPK3 (receptor interacting protein kinase 3) and the pseudokinase MLKL (mixed lineage kinase-like). Mice lacking caspase-8 display MLKL-dependent embryonic lethality, as do mice expressing catalytically inactive caspase-8 mutant C362A. However, Casp8C362A/C362A Mlkl-/- mice die in the perinatal period, whereas Casp8-/- Mlkl-/- mice are viable, indicating that inactive caspase-8 also has a pro-death scaffolding function. Here we show that caspase-8 C362A triggers ASC speck formation and caspase-1-dependent pyroptosis in MLKL-deficient intestinal epithelial cells (IECs) around embryonic day 18. Pyroptosis contributed to the perinatal lethal phenotype because a number of Casp8 C362A/C362A Mlkl-/- Casp1-/- mice survived beyond weaning. Transfection studies suggested inactive caspase-8 adopts a distinct conformation to wild-type caspase-8, enabling it to engage the caspase-1 adaptor ASC. Wild-type caspase-8 was found in the Triton X-100 soluble fraction, whereas wild-type caspase-8 inhibited with the pan-caspase inhibitor emricasan, or inactive caspase-8 mutant C362A, were detected in the insoluble fraction. Moreover, inhibited or inactive caspase-8 shifted ASC into the insoluble fraction. Perinatal lethality was recapitulated when expression of caspase-8 C362A was restricted to IECs, but intriguingly, only in the absence of MLKL. Hence, unanticipated plasticity in death pathways is revealed such that IECs can undergo caspase-1-dependent death when caspase-8-dependent apoptosis and MLKL-dependent necroptosis are inhibited.

ORGANISM(S): Mus musculus

PROVIDER: GSE132133 | GEO | 2019/09/20

REPOSITORIES: GEO