Ubiquitin-specific peptidase 11 promotes development of keloid derived fibroblasts by de-ubiquitinating TGF-β receptorII

Keloid scars occur as a result of abnormal wound healing caused by trauma or inflammation of the skin. The progression of keloids is dependent on genetic and environmental influences. The incidence is more prevalent in people with darker skin tones (African, Asian and Hispanic origin). Studies have demonstrated that transforming growth factor (TGF) β/Smad signalling has an essential function in keloid as well as that USP11 could modulate the activation of TGFβ/Smad signalling and impact the progression of the fibrotic disease. Nonetheless, the potential mechanisms of USP11 in keloid were still unclear. The authors postulated that USP11 up-regulates and augments the ability of proliferation, invasion, migration and collagen deposition of keloid-derived fibroblasts (KFBs) through deubiquitinating TGF-β receptor II (TβRII). Fibroblast cells were isolated from keloid scars in vitro. Lentivirus infection was utilized to knockdown and over-express the USP11 in KFBs. Influence of USP11 on proliferation, invasion and migration of KFBs, and expression level of TβRII, Smad2, Smad3, α-SMA, collagen1 and collagen3 were assayed by CCK8, scratching, transwell, Western blot and real-time quantitative polymerase chain reaction. The interactions between USP11 and TβRII were examined using ubiquitination assays and co-immunoprecipitation. To further confirm the role of USP11 in keloid growth, we performed animal experiments. the results have shown that down-regulated USP11 markedly suppressed the ability of proliferation, invasion and migration of keloid derived-fibroblasts in vitro and reduce the expression of TβRII, Smad2, Smad3, αSMA, collagen1 and collagen3. In addition, over-expression of USP11 demonstrated the contrary tendency. Ubiquitination experiments and co-immunoprecipitation demonstrated that USP11 was interacting with TβRII and deubiquitinated TβRII. Interferences with USP11 inhibited growth of keloid in vivo. Additionally, we have verified that knockdown of USP11 has no significant effect on normal skin fibroblasts. USP11 elevates the ability of proliferation, collagen deposition, invasion and migration of keloid–derived fibroblasts by deubiquitinating TβRII.