UCHL1 aggravates skin fibrosis through an IGF--1--induced Akt/mTOR/HIF--1a pathway in keloid

Keloid is a heterogeneous disease featured by the excessive production of extracellular matrix. It is a great challenge for both clinicians and patients regarding the exaggerated and uncontrolled outgrowth and the therapeutic resistance of the disease. In this study, we verified that UCHL1 was drastically upregulated in keloid fibroblasts. UCHL1 had no effects on cell proliferation and migration, but instead promoted collagen I and alpha-SMA expression that was inhibited by silencing UCHL1 gene and by adding in LDN--57444, a pharmacological inhibitor for UCHL1 activity as well. The pathological process was mediated by IGF-1 promoted Akt/mTOR/HIF-1a signaling pathway because inhibition of any of them could reduce the expression of collagen I and alpha-SMA driven by UCHL1 in fibroblasts. Also, we found that UCHL1 expression in keloid fibroblasts was promoted by M2 macrophages via TGF-beta 1. These findings extend our understanding of the pathogenesis of keloid and provide potential therapeutic targets for the disease.