Hypothesis

The age‑associated increase in AP‑1 binding to cis‑regulatory elements is driven by an age‑upregulated long non‑coding RNA, AGING‑R, which acts as a molecular scaffold that recruits AP‑1 (and its co‑activator p300) to aging‑associated enhancers while simultaneously sequestering AP‑1 away from youth‑associated promoters.

Mechanistic rationale

• AP‑1 functions as a master upstream controller of aging hallmarks by remodeling chromatin accessibility, converting youth‑associated regions into a closed state and opening aging‑associated regions {[longevity.technology/news/master-controller-of-aging-and-development-uncovered/]}
• This remodeling follows a predictable trajectory from development through senescence, reflecting progressive AP‑1 binding to cCREs {[imb.uq.edu.au/article/2024/06/revealing-master-controller-development-and-ageing]}
• Parallel epigenetic controllers such as the MLL complex and BMAL1‑mTORC1 axis demonstrate that transcriptional complexes can be tethered to specific genomic loci by non‑coding RNAs {[pubmed.ncbi.nlm.nih.gov/38177329/]} {[www.aging-us.com/article/100633/text]}
• Numerous lncRNAs (e.g., HOTAIR, MALAT1) serve as scaffolds that bring transcription factors and chromatin modifiers to target sites, providing a proven mechanism for RNA‑dependent targeting {[doi.org/10.1016/j.cell.2018.02.005]}
• We propose that AGING‑R expression is low in youth, rises with age due to mTORC1‑dependent transcription (consistent with BMAL1 loss‑of‑function leading to elevated mTOR activity), and that AGING‑R contains multiple AP‑1‑binding motifs and a p300‑interacting domain.

Testable predictions

1. Correlation – AGING‑R RNA levels will increase steadily across murine tissues from early adulthood to old age, mirroring the gain of accessibility at AP‑1‑bound aging enhancers (measured by ATAC‑seq).
2. Loss‑of‑function – siRNA or CRISPRi‑mediated knockdown of AGING‑R in aged fibroblasts will reduce AP‑1 occupancy at aging enhancers (ChIP‑seq for c‑Jun) and restore accessibility at youth‑associated promoters, decreasing senescence‑associated secretory phenotype (SASP) markers.
3. Gain‑of‑function – Ectopic expression of AGING‑R in young cells will prematurely recruit AP‑1 to aging enhancers, close youth‑associated regions, and accelerate hallmark phenotypes such as increased β‑galactosidase activity and reduced proliferation.
4. Pharmacological link – Rapamycin treatment will lower AGING‑R expression (via mTORC1 inhibition) and attenuate AP‑1‑driven chromatin remodeling, providing a mechanistic bridge between BMAL1‑mTORC1 signaling and the AP‑1/lncRNA axis.

Potential experimental approach

• Perform RNA‑seq on sorted young (3 mo) and old (24 mo) mouse dermal fibroblasts to identify lncRNAs with age‑dependent up‑regulation; validate candidates by qPCR.
• Use RNA‑antisense purification (RAP) coupled with mass spectrometry to detect AP‑1 subunits and p300 bound to AGING‑R.
• Conduct ChIP‑seq for c‑Jun and H3K27ac in control versus AGING‑R‑knockdown aged fibroblasts to map changes in enhancer activity.
• Assess functional hallmarks (SA‑β‑gal, γH2AX, mitochondrial ROS, SASP cytokines) after manipulation.
• Test rapamycin efficacy in wild‑type versus AGING‑R‑overexpressing mice to see if the drug’s anti‑aging effect is blunted when the lncRNA is forced high.

Implications

If validated, AGING‑R would represent a concrete molecular link that translates upstream signaling (mTORC1/BMAL1) into the epigenetic reprogramming driven by AP‑1, unifying several hallmarks under a single upstream controller. This would shift the focus from treating individual hallmarks to targeting the AP‑1‑lncRNA regulatory node as a potential geroprotective strategy.