Hypothesis

Obesity‑induced hypoxia triggers rapid YAP/TAZ activation in adipose fibroblasts, driving endotrophin release and a stiff collagen VI matrix that fuels inflammation. In contrast, chronic low‑grade stiffness in aged adipose tissue sustains integrin‑FAK signaling that pushes fibro‑adipogenic progenitors into a senescent state, secreting SASP factors that fibrosis independently of endotrophin.[1][2]

Mechanistic basis

• YAP/TAZ axis – Mechanical stretch from hypertrophied adipocytes activates YAP/TAZ, which transcriptionally upregulates CTGF and ENDO (endotrophin) and promotes collagen VI crosslinking via LOXL2.[3]
• Integrin‑FAK‑SASP axis – Persistent matrix tension engages α5β1 integrins, triggering FAK‑Src phosphorylation, p16^INK4a upregulation and a senescence-associated secretory phenotype rich in IGFBP7 and TIMP1 that stabilizes fibrosis.[4][5]

Testable predictions

1. It's expected that pharmacological inhibition of YAP/TAZ (e.g., verteporfin) in obese mice will reduce endotrophin levels and collagen VI deposition without altering senescent FAP numbers.
2. We don't yet know whether senolytic clearance of p16^INK4a+ FAPs in aged mice will decrease fibrosis markers (hydroxyproline, TIMP1) while YAP/TAZ activity remains unchanged; we predict it will.
3. We're hypothesizing that dual targeting (YAP/TAZ inhibitor + senolytic) will additively improve insulin tolerance in models that combine obesity and aging.

Experimental approach

• Models – HFD‑fed young mice (obesity model) and naturally aged mice (± HFD) to isolate each driver.[6]
• Interventions – Verteporfin (YAP/TAZ inhibitor), navitoclax or dasatinib+quercetin (senolytics), vehicle controls.
• Readouts – qPCR/Western for endotrophin, p16^INK4a, YAP nuclear localization; histology for collagen VI (Picrosirius red + collagen VI immunostaining); hydroxyproline assay; flow cytometry for ATMs and FAPs; glucose tolerance test.
• Analysis – Two‑way ANOVA with factors treatment and model; interaction term tests whether effects differ between obesity and aging.

Potential implications

If validated, this hypothesis reframes adipose fibrosis as a mechanobiological switch point: acute overload engages YAP/TAZ‑ endotrophin, while chronic load locks in senescence via integrin‑FAK. It suggests that timing and combinatorial therapy matter—early anti‑YAP/TAZ in obesity, senolytics in aged tissue, and that biomarkers like circulating endotrophin versus IGFBP7 could guide patient stratification. Such stratification could enrich clinical trials for senolytics or YAP/TAZ inhibitors, reducing noise from mixed etiology and accelerating approval.