Missense mutations in the MLKL ‘brace’ region lead to lethal neonatal inflammation in mice and are present in high frequency in humans

Abstract

SUMMARYWe have isolated a mouse strain with a single missense mutation in the gene encoding MLKL, the essential effector of necroptotic cell death. The resulting substitution lies within the two-helix ‘brace’ and confers constitutive, RIPK3 independent, killing activity to MLKL. Mice homozygous for MlklD139V develop lethal inflammation within days of birth, implicating the salivary glands and pericardium as hotspots for necroptosis and inflammatory infiltration. The normal development of MlklD139V homozygotes until birth, and the absence of any overt phenotype in heterozygotes provides important in vivo precedent for the capacity of cells to clear activated MLKL. These observations offer an important insight into the potential disease-modulating roles of three common human MLKL polymorphisms that encode amino acid substitutions within or adjacent to the brace region. Compound heterozygosity of these variants is found at up to 12-fold the expected frequency in patients that suffer from a pediatric autoinflammatory disease, CRMO.

Identification of MLKL membrane translocation as a checkpoint in necroptotic cell death using Monobodies

“…protein interactions | cell death | RIPK3 | programmed necrosis | protein engineering N ecroptosis is a caspase-independent cell death pathway that has been implicated in host defense to counter pathogens (1)(2)(3)(4)(5)(6)(7)(8), and its dysregulation, in the pathology of inflammatory diseases (9)(10)(11)(12)(13). Necroptotic signaling can be initiated by death receptor ligands, including tumor necrosis factor (TNF), engaging their cognate receptors.…”

The Killer Pseudokinase Mixed Lineage Kinase Domain-Like Protein (MLKL)

“…One of the major challenges with ascribing roles for necroptosis in pathologies is that different death modalities can cooccur in diseased tissues, as evidenced by apoptosis and necroptosis cooccurring in mice with hyperactive TNF signaling (Dannappel et al 2014;Rickard et al 2014a), and necroptosis and ferroptosis cooccurring following acute kidney injury (Müller et al 2017). Nevertheless, the recent discovery of a mouse strain harboring an activated MLKL mutant clearly implicates inflammation as an important contributor to necroptotic pathologies, as these animals succumbed to a lethal inflammatory syndrome within 6 days of birth (Hildebrand et al 2019). Consequently, much interest has arisen in therapeutically targeting the necroptosis pathway.…”