Abstract 125: Overexpression of the Transcription Factor Dlx5 in the Placenta of Preeclamptic Patients Leads to Decreased Trophoblast Proliferation - A Novel Mechanism Involving Loss of Imprinting

Abstract

Objectives: Preeclampsia (PE) is one of the most-common, life-threatening pregnancy complication that affects maternal and offspring health, with short and long-term implications. We hypothesize that epigenetic abnormalities and/or dysregulation of imprinted genes together with genes located in their proximity during placentation affect expression pattern of a broad spectrum of genes leading to preeclampsia. These genes can induce life-long epigenetic changes in the genome of the mother following preeclamptic pregnancy. Methods and Results: Using large-scale bioinformatical analysis of human placenta gene expression in 25 preeclamptic patients and 23 controls we identified characteristic pattern for PE. It consists of three clusters of patients, suggesting that preeclampsia is a complex, heterologous disease. Moreover, the analysis identified distal-less homeobox 5 (DLX5), a maternally expressed gene, which is significantly upregulated in preeclamptic placenta (1.5 fold). We confirmed upregulation of DLX5 on mRNA level in the early onset (0.8 (n=6), indicating that LOI is involved in overexpression of DLX5 in PE. DLX5 is primarily known as a developmental transcription factor and is crucial for bone development. Although DLX5 is highly expressed in human placenta, its function and the target genes in trophoblasts as well as its role during placentation still remains unknown. Using Sleeping Beauty (SB) transposon system, we stably overexpressed DLX5 in SGHPL-4 trophoblast cell line that significantly reduced trophoblast proliferation as indicated by high throughput sampler cell count (654.2 ± 395.5 vs. 1709 ± 1119) and MTT colorimetric assay (A570: 0.154 ± 0.097 vs. 0.29 ± 0.099). Conclusions: We show that the imprinted transcription factor DLX5 is upregulated in preeclampsia and propose loss of imprinting as one underlying mechanism. Overexpression of DLX5 in first trimester trophoblasts reduces cell proliferation. Our data support the importance of dysregulated epigenetic mechanism as an important feature in preeclampsia.