NEDD4 Is Involved in Inflammation Development during Keloid Formation

Keloids mark a chronic inflammatory disease characterized by a fibroproliferative disorder of the skin. A genome-wide association study showed that single-nucleotide polymorphism rs8032158 in the neural precursor cell-expressed NEDD4 gene, which has six protein-coding transcript variants (TVs), is genetically linked to keloids. Here, we show that the high frequency of risk allele C in rs8032158 in keloid patients is associated with a selectively higher expression of TV3 of NEDD4 to activate the NF-kB pathway. Comparisons of keloid scars with normal skin samples that do not have the single-nucleotide polymorphism allele and were derived from different anatomical sites showed stronger expressions of NEDD4 TV3 and activated forms of NF-kB and STAT3 in keloid scars. Forced expression or selective knockdown of NEDD4 TV3 increased or decreased NF-kB activation in vitro. Furthermore, NEDD4 knockdown suppressed NF-kBedependent inflammation development in vivo. Mechanistic analysis showed that NEDD4 TV3 is involved in NF-kB activation through its association with the adaptor protein RIP. These results suggest that NEDD4 TV3 is a potential diagnostic marker and therapeutic target for chronic skin diseases, including keloid.