Silencing of Fli1 Gene Mimics Effects of Preeclampsia and Induces Collagen Synthesis in Human Umbilical Arteries.

Abstract

Previously we demonstrated that in patients with preeclampsia elevated levels of endogenous Na/K-ATPase inhibitor, marinobufagenin, cause inhibition of Friend leukemia virus integration 1 (Fli1), a negative regulator of collagen-1 synthesis. We hypothesized that in vitro silencing of Fli1 in healthy human umbilical arteries would be associated with an increase in collagen-1 output, similar to the effect of preeclampsia in rat and human tissues. The isolated segments of healthy human umbilical arteries were tested for sensitivity to MBG and Fli1 silencing with Fli1 siRNA or control siRNA. Following 24-hour incubation of arteries with nanomolar concentrations of marinobufagenin, Fli1 expression was inhibited 5-fold (P < 0.001), and synthesis of collagen-1 increased 3 times (P < 0.01). Twenty-four-hour incubation of umbilical artery fragments with Fli1 siRNA caused a dramatic decrease of Fli1 (7-fold; P < 0.001) and cytoplasmic PKC δ (4-fold; P < 0.001) expression in comparison to control siRNA or untreated control, followed by elevation in procollagen (3-fold; P < 0.001) and collagen-1 (3-fold; P < 0.001) levels in vascular tissue. Our results show that after silencing the Fli1 gene in healthy human umbilical arteries a new phenotype emerges which is typical for preeclampsia and is associated with vascular fibrosis.