Inhibition of METTL3 attenuates renal injury and inflammation by alleviating TAB3 m6A modifications via IGF2BP2-dependent mechanisms

The role of N-6-methyladenosine (m6A) modifications in renal diseases is largely unknown. Here, we characterized the role of N-6-adenosine-methyltransferase-like 3 (METTL3), whose expression is elevated in renal tubules in different acute kidney injury (AKI) models as well as in human biopsies and cultured tubular epithelial cells (TECs). METTL3 silencing alleviated renal inflammation and programmed cell death in TECs in response to stimulation by tumor necrosis factor-alpha (TNF-alpha), cisplatin, and lipopolysaccharide (LPS), whereas METTL3 overexpression had the opposite effects. Conditional knockout of METTL3 from mouse kidneys attenuated cisplatin- and ischemic/reperfusion (I/R)-induced renal dysfunction, injury, and inflammation. Moreover, TAB3 [TGF-beta-activated kinase 1 (MAP3K7) binding protein 3] was identified as a target of METTL3 by m6A methylated RNA immunoprecipitation sequencing and RNA sequencing. The stability of TAB3 was increased through binding of IGF2BP2 (insulin-like growth factor 2 binding protein 2) to its m6A-modified stop codon regions. The proinflammatory effects of TAB3 were then explored both in vitro and in vivo. Adeno-associated virus 9 (AAV9)-mediated METTL3 silencing attenuated renal injury and inflammation in cisplatin- and LPS-induced AKI mouse models. We further identified Cpd-564 as a METTL3 inhibitor that had better protective effects against cisplatin- and ischemia/reperfusion-induced renal injury and inflammation than S-adenosyl-L-homocysteine, a previously identified METTL3 inhibitor. Collectively, METTL3 promoted m6A modifications of TAB3 and enhanced its stability via IGF2BP2-dependent mechanisms. Both genetic and pharmacological inhibition of METTL3 attenuated renal injury and inflammation, suggesting that the METTL3/TAB3 axis is a potential target for treatment of AKI.

Automated summary

The role of N-6-methyladenosine (m6A) modifications in renal diseases, particularly acute kidney injury (AKI), is still largely unknown. In this study, the researchers investigated the role of N-6-adenosine-methyltransferase-like 3 (METTL3) in AKI and found that its expression is elevated in renal tubules. They discovered that silencing METTL3 alleviated renal inflammation and programmed cell death in tubular epithelial cells (TECs) in response to stimulation, while overexpression of METTL3 had the opposite effects. Conditional knockout of METTL3 in mice also attenuated renal dysfunction, injury, and inflammation induced by AKI. Furthermore, the researchers identified TAB3 as a target of METTL3 and explored its proinflammatory effects. They also investigated the therapeutic potential of inhibiting METTL3 using an inhibitor called Cpd-564. Overall, they concluded that the METTL3/TAB3 axis may be a potential target for the treatment of AKI.