title: Marinobufagenin is an upstream modulator of Gadd45a stress signaling in preeclampsia.
abstract: Preeclampsia (PE) is a hypertensive disorder of pregnancy, in which marinobufagenin (MBG), a circulating cardiotonic steroid, is increased. The Gadd45a stress sensor protein is an upstream modulator of the pathophysiological changes observed in PE. However, the effects of MBG on Gadd45a stress signaling remain unknown. We examined the expression of Gadd45a, the sFlt-1 receptor, and p38, as well as caspase 3 and 8 activities in placental samples from four groups of rats. These were: normal pregnant (NP, n=8); pregnant rats which received weekly injections of desoxycorticosterone acetate and 0.9% saline as their drinking water (PDS, n=9); normal pregnant rats injected with MBG (NPM, n=8); and PDS rats injected with resibufogenin (RBG), an in vivo antagonist of MBG (PDSR, n=8). Utilizing human cytotrophoblast (CTB) cells, we examined the effect of MBG on these stress signaling proteins in vitro. Placental Gadd45a expression, caspase 3 and 8 activities, sFlt-1 concentrations, and sFlt-1 receptor expression were significantly higher in PDS and NPM compared to NP and PDSR rats. Gadd45a protein was significantly upregulated in the CTB cells when MBG was present in concentrations ≥1nM. Treatment with MBG (≥1nM) also significantly arrested cell cycle progression and activated the expression of the Gadd45a-mediated stress signaling proteins. Inhibition of Gadd45a through RNAi-mediation attenuated MBG-induced CTB cell stress signaling. In conclusion, MBG is involved in the alteration in Gadd45a stress signaling both in vivo and in vitro and RBG prevents these changes when administered in vivo.
authors.affiliation: Division of Nephrology and Hypertension, Department of Medicine, Texas A&M Health Science Center College of Medicine and Scott & White Memorial Hospital, Temple, TX 76508, USA.
authors.forename: Mohammad N
authors.initials: MN
authors.lastname: Uddin
authors.forename: Darijana
authors.initials: D
authors.lastname: Horvat
authors.forename: Sharon
authors.initials: S
authors.lastname: Demorrow
authors.forename: Enoch
authors.initials: E
authors.lastname: Agunanne
authors.forename: Jules B
authors.initials: JB
authors.lastname: Puschett
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002018:Bufanolides / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D008297:Male; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010920:Placenta / Q000187:drug effects / Q000378:metabolism; D011225:Pre-Eclampsia / Q000378:metabolism; D011247:Pregnancy; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects*; D014327:Trophoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D000097642:GADD45 Proteins
chemical_list: D002018:Bufanolides; D053148:Caspase 3; D053181:Caspase 8; D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; D040281:Vascular Endothelial Growth Factor Receptor-1; D014662:Vasoconstrictor Agents; D048051:p38 Mitogen-Activated Protein Kinases; C499073:Gadd45a protein, rat; D000097642:GADD45 Proteins; C005734:bufogenin; C093896:marinobufagenin; C501164:Flt1 protein, rat