Knockdown of CPEB1 and CPEB4 Inhibits Scar Formation via Modulation of TAK1 and SMAD Signaling

BACKGROUND: Cytoplasmic polyadenylation element binding (CPEB) proteins are sequence-specific RNA-binding proteins that control translation via cytoplasmic polyadenylation. We previously reported that CPEB1 or CPEB4 knockdown suppresses TAK1 and SMAD signaling in an in vitro study. OBJECTIVE: This study aimed to investigate whether suppression of CPEB1 or CPEB4 expression inhibits scar formation in a mice model of acute dermal wound healing. METHODS: CPEB1 and CPEB4 expression levels were suppressed by siRNA treatment. Skin wounds were created by pressure-induced ulcers in mice. Images of the wound healing were obtained using a digital camera and contraction was measured by ImageJ. mRNA and protein expression was analyzed using quantitative real time polymerase chain reaction and western blotting, respectively. RESULTS: Wound contraction was significantly decreased by pre-treatment with CPEB1 or CPEB4 siRNA compared to the control. Suppression of CPEB1 or CPEB4 expression decreased TAK1 signaling by reducing the levels of TLR4 and TNF-α, phosphorylated TAK1, p38, ERK, JNK, and NF-κB-p65. Decreased levels of phosphorylated SMAD2 and SMAD3 indicated a reduction in SMAD signaling as well. Consequently, the expression of α-SMA, fibronectin, and type I collagen decreased. CONCLUSION: CPEB1 siRNA or CPEB4 siRNA inhibit scar formation by modulating the TAK1 and SMAD signaling pathways. Our study highlights CPEB1 and CPEB4 as potential therapeutic targets for the treatment of scar formation.