RNA Sequencing of Gas6 induced Preeclamptic Rat Placenta

Preeclampsia (PE) is an obstetric complication that affects 2–8% of pregnancies and remains a leading cause of morbidity and mortality for both the mother and fetus. Recent research has focused on biomarkers that may indicate disease onset and models for the study of PE. One such potential biomarker is the growth arrest specific protein 6 (Gas6). Gas6 binds to the TAM family of tyrosine kinase receptors, with primary affinity for the Axl receptor. Axl‐mediated signaling is implicated in cellular proliferation and migration, and we’ve demonstrated that Axl activation by Gas6 during pregnancy induces PE in the rat, including symptoms such as increased blood pressure, proteinuria, altered trophoblast invasion, and increased inflammatory cytokines. Our objective was to elucidate changes in gene expression induced by Gas6/Axl in the developing placenta. Pregnant Holtzman Sprague Dawley rats were treated with Gas6, or Gas6 and the Axl inhibitor R428, from gestational day (GD) 7.5–17.5. Control rats received saline injections during the same period. Tissues were collected at GD 18 and snap frozen in liquid nitrogen. Placental RNA was isolated and submitted to the sequencing center at Brigham Young University. Quality filtering was performed prior to alignment, and alignment for each sample was between 98.0–98.4%. Significance was noted as an adjusted p value of < 0.05. Analysis of the RNA sequencing data identified 123 genes that were affected by Gas6 administration. Of these, 44 genes were not responsive to Axl inhibition, 29 were returned to baseline levels, and 50 were mildly to moderately responsive to Axl inhibition. Examination of enriched gene ontologies identified several impacted biological processes including cellular proliferation and apoptosis, RNA stability, lipoxin processes and metabolism, and transcription in response to stress. These initial findings highlight several options for clarifying the molecular mechanisms of PE mediated by Gas6. Further research should examine translational effects in greater detail. Support or Funding Information This work was supported by a grant from the Flight Attendant’s Medical Research Institute (FAMRI, PRR and JAA) and a BYU Mentoring Environment Grant (JAA and PRR).