Abstract
Introduction Mutations in the bone morphogenetic protein receptor 2 (BMPR2) gene underlie heritable PAH. PAH occurs more frequently in women. MicroRNAs (miRs) are gene regulators involved in vascular processes including proliferation.
Aims We investigated miR expression in mice with a BMPR2 R899X mutation.
Methods miRNA and mRNA expression by qRTPCR and protein by westerns were determined in human pulmonary arterial smooth muscle cells (hPASMCs). Proliferation was assessed by cell counts. In vivo levels of oestrogen were depleted in female mice using the aromatase inhibitor anastrozole (3mg/kg/day for 2 weeks). All data, n>6.
Results Expression of miR96 was decreased from 1±0.09 to 0.09±0.002 (p<0.001) in female BMPR2 R899X mice PASMCs vs. female wild type (WT), not male. miR96 targets the gene for 5HT1B receptor and both 5HT1B mRNA (4.82±1.47 vs. 1.00±0.67, p<0.05) and protein (0.644±0.14 vs. 0.274±0.03, p<0.05) were increased in the female (not male) BMPR2 R899X vs. WT PASMCs. miR96 expression was decreased by ∼82% and 5HT1B protein elevated by ∼61% in PASMCs from female PAH patients (not males) vs. Controls and associated with increased serotonin-induced proliferation. Pre-miR-96 transfected in human PASMCs decreased 5HT1B protein expression by 40%. Depletion of oestrogen caused a ∼77% increased expression of miR96 and an ∼84% decrease in 5HT1B expression in whole lung. In hPASMCs, 1nM oestrogen decreased miR96 expression by ∼80% and increased 5HT1B expression 2-fold.
Conclusions Oestrogen-induced decreased miR96 expression, leading to derepressed 5HT1B expression may predispose female PASMCs to proliferation, contributing to the development of PAH.
- © 2014 ERS
