Rubicon-deficiency sensitizes mice to mixed lineage kinase domain-like (MLKL)-mediated kidney ischemia-reperfusion injury

Wulf Tonnus,Sophie Locke,Douglas R Green,Stefan R Bornstein,Anne Von Mässenhausen,Claudia Meyer,Francesca Maremonti,Andreas Linkermann,Lena Eggert

doi:10.1038/s41419-022-04682-3

Abstract

The cytosolic protein rubicon (RUBCN) has been implicated in the removal of necrotic debris and autoimmunity. However, the role of RUBCN in models of acute kidney injury (AKI), a condition that typically involves necrotic kidney tubules, was not investigated. Here, we demonstrate that RUBCN-deficient mice are hypersensitive to renal damage induced by ischemia-reperfusion injury (IRI) and cisplatin-induced AKI. Combined deficiency of RUBCN and mixed lineage kinase domain-like (MLKL) partially reversed the sensitivity in the IRI model suggesting that the absence of RUBCN sensitizes to necroptosis in that model. Necroptosis is known to contribute to TNFα-induced severe inflammatory response syndrome (SIRS), but we detected no statistically significant difference in overall survival following injection of TNFα in RUBCN-deficient mice. We additionally generated RUBCN-deficient mice which lack gasdermin D (GSDMD), the terminal mediator of pyroptosis, but no reversal of the AKI phenotype was observed. Finally, and in contrast to the previous understanding of the role of RUBCN, we did not find a significant autoimmune phenotype in RUBCN-deficient mice, but detected chronic kidney injury (CKD) in aged RUBCN-deficient mice of both sexes. In summary, our data indicate that RUBCN-deficient mice are hypersensitive to kidney injury.

Highlights

Phagocytosis of dead or dying cells was studied in detail over the last decade [1, 2]
We and others recently demonstrated that mixed lineage kinase domain-like (MLKL)-mediated necroptosis is involved in acute kidney injury in mouse models [17–20] and in humans [21]
We demonstrate that RUBCN-deficient mice are hypersensitive to acute kidney injury (AKI), an effect that is partially reversed on the combined loss of RUBCN and MLKL, but not RUBCN and gasdermin D (GSDMD)

Summary

Introduction

Phagocytosis of dead or dying cells was studied in detail over the last decade [1, 2]. RUBCN was demonstrated to be involved in a specific type of cellular uptake of extracellular content referred to as LC3-associated phagocytosis (LAP) [9–12]. This process is thought to be critically important in the removal of necrotic debris and may be critical for tissues to allow regeneration following acute injury while avoiding autoimmunity [13]. Acute kidney injury (AKI) is associated with the loss of nephrons and may fundamentally contribute to the progression of chronic kidney disease [14–16]. Acute tubular necrosis is a hallmark condition of AKI, and we reasoned that failure to remove necrotic debris following AKI might affect renal injury in murine models of AKI. Other forms of regulated necrosis, such as ferroptosis [22, 23] and gasdermin D (GSDMD)-mediated pyroptosis [24], are potentially involved in AKI

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Results

Conclusion