Axis of serotonin -pERK-YAP in liver regeneration

Serotonin and YAP exhibit a vital role in regulating cell proliferation and wound-healing response. The aim of the study was to investigate whether 5-HT could promote liver regeneration by activating YAP.

PH models were established by WT and TPH1-/- mice. ELISA, RT-PCR, western blot, immunohistochemistry, flow cytometry and MTT assay were used to assess the level of 5-HT and YAP and proliferation after PH.

We found that 5-HT level was lower in the serum and liver of TPH1-/- mice. After PH, TPH1-/- mice, lacking in 5-HT, demonstrated worse regenerative ability and suffered more severe liver injury. Additionally, YAP expression was also lower in TPH1-/- mice. Moreover, we found that YAP expression was prominent within the first three days following PH. Similarly, 5-HT could promote cell proliferation by upregulating YAP expression in L-O2 cells. As predicted, using YAP-siRNA sharply reduced the proliferative capacity mediated by 5-HT. Further study also indicated that ERK participated in the regulation of YAP induced by 5-HT. By using an ERK inhibitor, the YAP expression and cell proliferation induced by 5-HT were both suppressed. Although YAP-siRNA was used to block YAP expression, pERK and ERK expression were not affected. Taken together, these data showed that 5-HT contributed to liver regeneration by regulating YAP expression, which at least in part, was by activation of pERK.

A role of the 5-HT-pERK-YAP axis in liver regeneration emerged from our study and might be a potential target to promote regeneration and injury repair.