The TGF-β/UCHL5/Smad2 Axis Contributes to the Pathogenesis of Placenta Accreta

Placenta accreta is a high-risk condition causing obstetric crisis and hemorrhage; however, its pathogenesis remains unknown. We aimed to identify the factors contributing to trophoblast invasiveness and angiogenic potential, which in turn drive the pathogenesis of placenta accreta. We focused on the transforming growth factor (TGF)-beta 1-Smad pathway and investigated the intrinsic relationship between the time- and dose-dependent inhibition of the ubiquitinating enzyme UCHL5 using bAP15, a deubiquitinase inhibitor, after TGF-beta 1 stimulation and the invasive and angiogenic potential of two cell lines, gestational choriocarcinoma cell line JEG-3 and trophoblast cell line HTR-8/SVneo. UCHL5 inhibition negatively regulated TGF-beta 1-induced Smad2 activation, decreasing extravillous trophoblast invasiveness. Smad1/5/9 and extracellular signal-regulated kinase (ERK) were simultaneously activated, and vascular endothelial growth factor was secreted into the trophoblast medium. However, extravillous trophoblast culture supernatant severely impaired the vasculogenic potential of human umbilical vein endothelial cells. These results suggest that the downstream ERK pathway and Smad1/5/9 potentially regulate the TGF-beta 1-Smad pathway in extravillous trophoblasts, whereas Smad2 contributes to their invasiveness. The abnormal invasive and angiogenic capacities of extravillous cells, likely driven by the interaction between TGF-beta 1-Smad and ERK pathways, underlie the pathogenesis of placenta accreta.

Automated summary

Placenta accreta is a high-risk condition causing obstetric crisis and hemorrhage, and its pathogenesis is not yet fully understood. This study identified the potential factors involved in trophoblast invasiveness and angiogenic potential that contribute to the development of placenta accreta. The study focused on the TGF-beta 1-Smad pathway and investigated the inhibitory effect of UCHL5 using bAP15 on trophoblast cells. The results suggest that the interaction between TGF-beta 1-Smad and ERK pathways is involved in the abnormal invasive and angiogenic capacities of extravillous cells.