Identification of integrin-alpha 4, Rb1, and syncytin a as murine placental target genes of the transcription factor GCMa/Gcm1
JOURNAL OF BIOLOGICAL CHEMISTRY
Authors: Schubert, Steffen Wolfgang; Lamoureux, Nicolas; Kilian, Karin; Klein-Hitpass, Ludger; Hashemolhosseini, Said
Abstract
Members of the GCM( glial cells missing) transcription factor family have been shown to act as master regulators in different cells during mammalian and fly development being responsible for processes including gliogenesis, hematopoiesis, placental formation, and development of the parathyroidea. In the central nervous system of flies, several target genes for GCM have been reported, namely repo, pointed, and tramtrack. In mammals, two GCM genes are known (GCMa and GCMb), but the knowledge of their target genes is very limited. Here, we present for the first time a global approach aimed to identify GCMa target genes. We found 66 genes up-regulated and 11 genes down-regulated in GCMa-deficient chorionic tissue of mice at embryonic day 9.5. Moreover, we verified by quantitative reverse transcription-PCR all 11 down-regulated genes. The two most strongly down-regulated genes, integrin-alpha 4 and retinoblastoma (Rb1), were further analyzed by promoter studies. Additionally, we identified down-regulation of the murine syncytin A gene, which is fundamental for syncytiotrophoblast formation. Finally, we proved strong down-regulation of integrin-alpha 4 and Rb1 transcript levels by in situ hybridization in murine GCMa-deficient placentae at embryonic day 9.5. Our data demonstrate for the first time that genes encoding key regulators of placental tissue formation and architecture are regulated by GCMa.
Reactive oxygen species from mitochondria impacts trophoblast fusion and the production of endocrine hormones by syncytiotrophoblasts
PLOS ONE
Authors: Walker, O'Llenecia S.; Ragos, Rehginald; Wong, Michael K.; Adam, Mohamed; Cheung, Anson; Raha, Sandeep
Abstract
The placenta, a tissue that is metabolically active and rich in mitochondria, forms a critical interface between the mother and developing fetus. Oxidative stress within this tissue, derived from the dysregulation of reactive oxygen species (ROS), has been linked to a number of adverse fetal outcomes. While such outcomes have been associated with mitochondrial dysfunction, the causal role of mitochondrial dysfunction and mitochondrially generated ROS in altering the process of placentation remains unclear. In this study, mitochondrial complex I activity was attenuated using 10 nM rotenone to induce cellular oxidative stress by increasing mitochondrial ROS production in the BeWo choriocarcinoma cell line. Increased mitochondrial ROS resulted in a significant decrease in the transcripts which encode for proteins associated with fusion (GCM1, ERVW-1, and ERVFRD-1) resulting in a 5-fold decrease in the percentage of BeWo fusion. This outcome was associated with increased indicators of mitochondrial fragmentation, as determined by decreased expression of MFN2 and OPA1 along with an increase in a marker of mitochondrial fission (DRP1). Importantly, increased mitochondrial ROS also resulted in a 5.0-fold reduction of human placental lactogen (PL) and a 4.4-fold reduction of insulin like growth factor 2 (IGF2) transcripts; hormones which play an important role in regulating fetal growth. The pre-treatment of rotenone-exposed cells with 5 mM N-acetyl cysteine (NAC) resulted in the prevention of these ROS mediated changes in BeWo function and supports a central role for mitochondrial ROS signaling in the maintenance and function of the materno-fetal interface.