Hypothesis

Senescent cells in aged kidney cortex establish a mechanochemical niche that fuels tubular epithelial dedifferentiation through integrin‑αvβ6–dependent capture of tenascin‑C and subsequent mitochondrial transfer via tunneling nanotubes.

Mechanistic premise

Recent spatial transcriptomics of IPF lung showed senescence‑associated basaloid cells expressing ITGAV and ITGB6, enabling reception of tenascin‑C‑rich ECMSpatial Transcriptomics of Aged Tissue Niches. Parallel work on cytoskeletal memory suggests that stressed cells retain structural cues that influence neighboring phenotypesCytoskeletal Archive: Why Your Cells Are Still Living in Last Year's Neighborhood. Finally, maps of tissue heterogeneity argue that localized niches drive systemic aging phenotypesThe Spatial Heterogeneity Paradox: Are We Missing the Aging Architecture?.

We propose that, in aged kidney, a subset of CDKN2A‑positive senescent pericytes upregulates the same integrin heterodimer, creating high‑affinity anchors for tenascin‑C deposited by stressed endothelial cells. This ECM‑integrin clutch triggers Src‑FAK signaling, which phosphorylates dynamin‑2 and promotes the formation of tunneling nanotubes (TNTs) toward adjacent proximal tubular epithelial cells. Through TNTs, senescent pericytes donate depolarized mitochondria, elevating ROS in the epithelium and stabilising HIF‑1α, which drives a Notch‑dependent dedifferentiation program reminiscent of epithelial‑to‑mesenchymal transition.

Testable predictions

• Prediction 1: In kidney sections from 24‑month‑old mice, immunofluorescence will show colocalization of CDKN2A, ITGAV/ITGB6, and tenascin‑C specifically in pericytes surrounding cortical tubuli, with a Pearson r > 0.6 (VisiumHD validation)VisiumHD platform performance.
• Prediction 2: Inhibition of integrin‑αvβ6 (using monoclonal antibody 10D5) will reduce TNT density (measured by LifeAct‑GFP labeling) by >50% and decrease mitochondrial transfer (MitoTracker overlap) in cultured kidney pericytes co‑cultured with tubular epithelial cells.
• Prediction 3: Conditional knockout of Tenasc‑C in endothelial cells will attenuate senescent pericyte activation (lower SASP IL‑6, PAI‑1) and limit epithelial dedifferentiation markers (Vimentin, α‑SMA) in aged mice, without affecting overall senescence burden.
• Prediction 4: Supplementing aged kidney cultures with exogenous healthy mitochondria will rescue epithelial ATP levels and suppress Notch‑target transcription (Hes1) even when integrin‑αvβ6 is engaged.

Falsifiability

If any of the above manipulations fail to alter the predicted readouts beyond statistical noise (p > 0.05, n ≥ 6 biological replicates), the hypothesis is refuted. Conversely, consistent support across orthogonal assays (spatial transcriptomics, live‑cell TNT imaging, functional metabolism) would substantiate the model.

Broader impact

Linking integrin‑ECM clutch to intercellular organelle trafficking provides a mechanistic bridge between static senescence maps and dynamic functional decline in aged organs, offering a druggable axis distinct from senolytic clearance.