Targeting RIPK3 oligomerization blocks necroptosis without inducing apoptosis.

Receptor-interacting serine/threonine-protein kinase 3 (RIPK3) is a central protein in necroptosis with great potential as a target for treating necroptosis-associated diseases, such as Crohn's disease. However, blockade of RIPK3 kinase activity leads to unexpected RIPK3-initiated apoptosis. Herein, we found that PP2, a known SRC inhibitor, inhibits TNF-α-induced necroptosis without initiating apoptosis. Further investigation showed that PP2 acts as an inhibitor of not only SRC but also RIPK3. PP2 does not disturb the integrity of the RIPK1-RIPK3-mixed lineage kinase domain-like pseudokinase (MLKL) necroptosome or the autophosphorylation of RIPK3 at T231/S232 but disrupts RIPK3 oligomerization, thereby impairing the phosphorylation and oligomerization of MLKL. These results demonstrate the essential role of RIPK3 oligomerization in necroptosis and suggest a potential RIPK3 oligomerization-targeting strategy for therapeutic development.