Altered expression of COP9 signalosome proteins in preeclampsia

The presumptive factors that are released by the preeclamptic placenta to cause maternal disease are less well known. The constitutive photomorphogenic-9 (COP9) signalosome (CSN) complex, a multifunctional protein complex involved in modulating signal transduction, gene transcription, and protein stability in cells. Although the roles of most CSN components in early embryonic development have been studied, their role in preeclamptic human placentas is not known. Thus, this study was aimed to show the localization and the protein expression of CSN1 and CSN5 in normal and preeclamptic placenta.

The distribution and the protein expression of CSN1 and CSN5 were analyzed in normal (n: 15) and preeclamptic (n: 15) human placenta by using immunohistochemistry (IHC) and Western blotting.

CSN1 and CSN5 were mainly localized in the vascular endothelium, syncytiotrophoblast, stromal and Hofbauer cells in normal and preeclamptic placentas. However, a stronger immunoreactivity and protein expression for CSN1 and CSN5 were observed in preeclamptic placentas compared to normal term placentas. Western blotting of the tissue extracts confirmed the IHC results.

Our results suggest that an increased level of CSN1 and CSN5 as an important part of the ubiquitin proteasome system (UPS) might be associated with the pathophysiology of preeclampsia.