Targeted Degradation of Receptor-Interacting Protein Kinase 1 to Modulate the Necroptosis Pathway.

Necroptosis is a highly regulated form of necrotic cell death that plays an essential role in pathogen defense and tissue homeostasis. Abnormal regulation of the necroptotic pathway has been implicated in the pathogenesis of various human diseases, including cancer, inflammatory, and neurodegenerative diseases. Receptor-interacting protein kinase 1 (RIPK1) serves as a crucial regulator of the necroptotic signaling pathway and has been identified as a potential therapeutic target. Mechanistically, RIPK1 serves as both a protein kinase and a scaffolding protein, fulfilling its dual function through a combination of kinase activity-dependent and kinase activity-independent mechanisms. Thus, employing a targeted RIPK1 knockdown strategy is a highly effective means of inhibiting RIPK1 functions. To achieve a targeted RIPK1 knockdown, we generated a RIPK1-PROTAC, MS2031, by connecting the ZB-R-55 RIPK1 binder to the VHL ligand, thereby recruiting the CUL2-RING-VHL (CRL2^VHL) E3 ubiquitin ligase complex for targeted degradation of RIPK1 through the 26S proteasome. Notably, MS2031 treatment effectively reduced the abundance of RIPK1 protein in the nanomolar range in various cell lines we examined, including HT-29 and T47D cells, and modulated the necroptosis signaling pathway. These results suggest that MS2031 may hold potential for the treatment of human diseases resulting from aberrant regulation of RIPK1.