Circadian clock gene Clock is involved in the pathogenesis of preeclampsia through hypoxia

To study the effect of the circadian clock gene Clock on the biological behavior of trophoblasts and its role in the pathogenesis of preeclampsia.

Quantitative real-time polymerase chain reaction (RT-qPCR) was used to detect the expression of Clock mRNA. Western blot and immunohistochemistry were used to detect the expression and localization of Clock protein. CoCl₂ was used to induce the hypoxic trophoblast cells. Cell invasion assay, wound healing assay and MTT assays were used to detect the invasion, migration, and proliferation ability. Reduced uterine perfusion pressure (RUPP) rat model was established by surgically clamping the abdominal aorta and uterine arteries. Transfection of si-Clock was used to silencing the expression of Clock.

Clock mRNA expression was increased in placenta of preeclampsia and CoCl₂-induced hypoxic trophoblasts, while protein was decreased. But the trend was opposite in RUPP rat models. Hypoxia can also change the expression rhythm of Clock. The proliferation, migration and invasion ability of trophoblasts decreased after hypoxia, while these abilities restored to near normal level after silencing Clock.

The expression of Clock gene in human placenta tissue, hypoxia cell model and RUPP rat model suggests that it may regulate the biological behavior of trophoblast cells through hypoxia, and then participate in the pathogenesis of preeclampsia.