A stress-induced cilium-to-PML-NB route drives senescence initiation

Abstract Cellular senescence contributes to tissue homeostasis and age-related pathologies. However, how senescence is initiated in damaged cells remains vague. Here, we discover that irreparable stresses induce transient biogenesis of cilia, which are used by stressed cells to directly communicate with the promyelocytic leukemia nuclear bodies (PML-NBs), the validated stress signaling hub, to initiate senescence responses. Mechanistically, a ciliary ARL13B-ARL3 GTPase cascade negatively regulates the association of transition fiber protein FBF1 and SUMO-conjugating enzyme UBC9. Irreparable stresses downregulate the ciliary ARLs to release UBC9, which SUMOylates FBF1 at the ciliary base. SUMOylated FBF1 then translocates to PML-NBs to promote PML-NB-dependent senescence initiation. Remarkably, Fbf1 suppression effectively subdues global senescence burden and prevents associated health-span decline in irradiation-treated mice. Collectively, our findings assign primary cilia a central role in inducing senescence program and identify them as promising targets to dampen senescence-associated detrimental damage in future senotherapy strategies.