A renal YY1-KIM1-DR5 axis regulates the progression of acute kidney injury.

Acute kidney injury (AKI) exhibits high morbidity and mortality. Kidney injury molecule-1 (KIM1) is dramatically upregulated in renal tubules upon injury, and acts as a biomarker for various renal diseases. However, the exact role and underlying mechanism of KIM1 in the progression of AKI remain elusive. Herein, we report that renal tubular specific knockout of Kim1 attenuates cisplatin- or ischemia/reperfusion-induced AKI in male mice. Mechanistically, transcription factor Yin Yang 1 (YY1), which is downregulated upon AKI, binds to the promoter of KIM1 and represses its expression. Injury-induced KIM1 binds to the ECD domain of death receptor 5 (DR5), which activates DR5 and the following caspase cascade by promoting its multimerization, thus induces renal cell apoptosis and exacerbates AKI. Blocking the KIM1-DR5 interaction with rationally designed peptides exhibit reno-protective effects against AKI. Here, we reveal a YY1-KIM1-DR5 axis in the progression of AKI, which warrants future exploration as therapeutic targets.

Menadione sodium bisulfite inhibits the toxic aggregation of amyloid-ß(1-42).

Protein misfolding and aggregation are associated with amyloidosis. The toxic aggregation of amyloid-ß 1-42 (Aß42) may disrupt cell membranes and lead to cell death and is thus regarded as a contributing factor in Alzheimer's disease (AD). 1,4-naphthoquinone (NQ) has been shown to exhibit strong anti-aggregation effects on amyloidogenic proteins such as insulin and α-synuclein; however, its high toxicity and poor solubility limit its clinical application. Menadione sodium bisulfite (MSB, also known as vitamin K3), is used clinically in China to treat hemorrhagic diseases caused by vitamin K deficiency and globally as a vitamin K supplement. We hypothesized that MSB could inhibit amyloid formation since its backbone structure is similar to NQ. To test our hypothesis, we first investigated the effects of MSB on Aß42 amyloid formation in vitro. We found that MSB inhibited Aß42 amyloid formation in a dose dependent manner, delayed the secondary structural conversion of Aß42 from random coil to ordered ß-sheet, and attenuated the ability of Aß42 aggregates to disrupt membranes; moreover, the quinone backbone rather than lipophilicity is esstial for the inhibitory effects of MSB. Next, in cells expressing a pathogenic APP mutation (Osaka mutation) that results in the formation of intraneuronal Aß oligomers, MSB inhibited the intracellular aggregation of Aß. Moreover, MSB treatment significantly extended the life span of Caenorhabditis elegans CL2120, a strain that expresses human Aß42. Together, these results suggest that MSB and its derivatives may be further explored as potential therapeutic agents for the prevention or treatment of AD.

Regulation of mammalian siderophore 2,5-DHBA in the innate immune response to infection.

Competition for iron influences host-pathogen interactions. Pathogens secrete small iron-binding moieties, siderophores, to acquire host iron. In response, the host secretes siderophore-binding proteins, such as lipocalin 24p3, which limit siderophore-mediated iron import into bacteria. Mammals produce 2,5-dihydroxy benzoic acid, a compound that resembles a bacterial siderophore. Our data suggest that bacteria use both mammalian and bacterial siderophores. In support of this idea, supplementation with mammalian siderophore enhances bacterial growth in vitro. In addition, mice lacking the mammalian siderophore resist E. coli infection. Finally, we show that the host responds to infection by suppressing siderophore synthesis while up-regulating lipocalin 24p3 expression via TLR signaling. Thus, reciprocal regulation of 24p3 and mammalian siderophore is a protective mechanism limiting microbial access to iron.