Relationship between Keloid Formation and YAP/TAZ Signaling

Summary: YAP (yes-Associated protein) and TAZ (transcriptional coactivator with PDZ-binding motif) are part of a classical pathway that controls contact inhibition in the Hippo pathway. YAP and TAZ were recently reported to act as nuclear relays of mechanical signals that communicate extracellular matrix rigidity and cell shape. However, the role of YAP/TAZ signaling in keloid formation is unclear. Here, we used immunohistochemistry to investigate YAP/TAZ expression in keloid and nonaffected lesions. YAP/TAZ expression in keloid fibroblasts had a greater tendency to localize to the nucleus relative to that seen in fibroblasts from unaffected tissues. Meanwhile, keratinocytes or endothelial cells from either keloid or unaffected tissues showed no significant differences in YAP/TAZ expression patterns. These results suggest that YAP/TAZ nuclear localization in keloid fibroblasts might activate Hippo signaling and may play an important role in gene expression that affects keloid formation and stiffness.