Model Links Knee Fat Proteins to Cartilage Gene Activity
On 22 August, a study appeared in Aging Cell, 22 August showing how to trace the path from extracellular proteins to cellular response. The authors combined data on age‑related changes in the knee infrapatellar fat pad with a map of gene activity in human cartilage, then compared the prediction with earlier cell experiments. Chondrocytes reside next to the infrapatellar fat pad, which secretes proteins whose composition shifts with age.
In a 2025 experiment, old mouse chondrocytes responded differently to medium from young versus old fat pads. Medium from young pads boosted production of extracellular matrix proteins, the material that supports cartilage. This raised the question of which cell‑surface receptors transmit the external signal to alter gene expression inside chondrocytes.
To answer it, the researchers took 30 proteins that differed between young and old fat‑pad secretions and used the NicheNet database to predict receptors that could bind them. They mapped those receptors onto a gene‑network of human cartilage built from 18 healthy and 20 osteoarthritic knee samples. Starting from the receptors, an algorithm ranked genes by their proximity in the network.
The prediction was tested against a published experiment where old mouse chondrocytes were incubated for 72 hours in young or old fat‑pad medium; 84 genes changed activity between the two conditions. The model and the data agreed on pathways of cellular respiration, including assembly of mitochondrial complex I
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PubMed Central (PMC)
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