Lysosome-Golgi Contact Sites as Regulators of Senescence-Associated Inflammation

/ ABSTRACT Chronic, low-grade inflammation is a hallmark of aging and a key driver of multiple age-related diseases. Accumulated senescent cells in aged tissues contribute to local and systemic inflammation by releasing a range of pro-inflammatory factors, collectively termed the senescence-associated secretory phenotype (SASP). Accordingly, there is growing interest in developing pharmacologic strategies to eliminate senescent cells and promote healthy aging. While senolytic drugs show promise, their off-target effects and dose-limiting toxicities constrain clinical use. An emerging alternative is the development of senomorphic therapies that suppress the SASP without inducing senescent cell clearance. However, progress has been hampered by an incomplete understanding of the regulatory mechanisms—particularly persistent NF-κB activation—that sustain SASP expression. Our recent work has uncovered a novel, spatially encoded mechanism underlying chronic inflammatory signaling in senescent cells. We identified a previously unrecognized class of lysosome–Golgi membrane contact sites (LG-MCSs) that form de novo during senescence and appear to act as structural scaffolds for the STING signalosome—a complex comprising the adaptor STING and the kinases TBK1 and IKKε, which together activate NF-κB. Unlike in canonical immune signaling, where STING is rapidly degraded via lysosomal routing after activation, we propose that senescent cells reorganize their organelle architecture to stabilize STING at LG-MCSs, shielding it from degradation and maintaining persistent signalosome activity. This R21 project will define the molecular architecture and functional role of LG-MCSs in sustaining chronic STING– NF-κB signaling. In Aim 1, we will use split-TurboID proximity labeling and quantitative mass spectrometry to generate a proteomic blueprint of LG-MCSs in senescent cells, identifying key tethering and signaling proteins. In Aim 2, we will employ CRISPR-based gene editing and the light-inducible OptoPBer system to manipulate LG-MCS formation in live cells and assess downstream effects on STING localization, NF-κB activation, and SASP gene expression. In addition to in vitro models of replicative and oncogene-induced senescence in normal human fibroblasts and epithelial cells, we will validate key findings in primary cells from aged donors and from individuals with Hutchinson-Gilford Progeria and Werner Syndromes—capturing both physiological and pathological contexts of aging. By establishing a new spatial framework for chronic inflammatory signaling in senescence, this project will generate foundational proof-of-concept data for a novel class of organelle-targeted senomorphic therapies. Aligned with the high-risk, high-reward mission of the R21 mechanism, these studies will lay the groundwork for future R01 research programs aimed at mitigating age-associated inflammation and promoting healthy aging through next-generation, organelle-based interventions. Project Number: 1R21AG100775-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute on Aging (NIA) | Principal Investigator: Joe Nassour | Institution: UNIVERSITY OF COLORADO DENVER, Aurora, CO | Award Amount: $429,000 | Activity Code: R21 | Study Section: Cellular Mechanisms in Aging and Development Study Section[CMAD] View on NIH RePORTER: https://reporter.nih.gov/project-details/11356092