A Sex-Specific MicroRNA-96/5-Hydroxytryptamine 1B Axis Influences Development of Pulmonary Hypertension

Abstract

Rationale: Females are predisposed to pulmonary arterial hypertension (PAH); evidence suggests that serotonin, mutations in the bone morphogenetic protein receptor (BMPR) II gene, and estrogens influence development of PAH. The 5-hydroxytryptamine 1B receptor (5-HT 1B R) mediates human pulmonary artery smooth muscle cell (hPASMC) proliferation.Objectives: We aimed to determine whether selected microRNAs (miRNAs) expressed in PASMCs are influenced by sex, BMPR-II mutations, and estrogens, and contribute to PASMC proliferation in PAH.Methods: Expression levels of miRNAs targeting genes related to PAH, estrogen, and serotonin were determined by quantitative RT-PCR in hPASMCs and mouse PASMCs harboring a heterozygous mutation in BMPR-II (BMPR-II R899X1/2 PASMCs). miRNA-96 targets 5-HT 1B R and was selected for further investigation. miRNA target validation was confirmed by luciferase reporter assay. Precursor miRNA-96 was transfected into hPASMCs to examine effects on proliferation and 5-HT 1B R expression. The effect of a miRNA-96 mimic on the development of hypoxic pulmonary hypertension in mice was also assessed.Measurements and Main Results: miRNA-96 expression was reduced in BMPR-II R899X1/2 PASMCs from female mice and hPASMCs from female patients with PAH; this was associated with increased 5-HT 1B R expression and serotonin-mediated proliferation. 5-HT 1B R was validated as a target for miRNA-96. Transfection of precursor miRNA-96 into hPASMCs reduced 5-HT 1B R expression and inhibited serotonin-induced proliferation. Restoration of miRNA-96 expression in pulmonary arteries in vivo via administration of an miRNA-96 mimic reduced the development of hypoxia-induced pulmonary hypertension in the mouse. We recently demonstrated, in the hypoxic mouse and Sugen 5,416/hypoxic rat models, that the therapeutic effect of anastrozole, an inhibitor of estrogen synthesis, was only observed in females, and was related to restoration of BMPR-II

17β-Estradiol mediates superior adaptation of right ventricular function to acute strenuous exercise in female rats with severe pulmonary hypertension

“…One potential theory to reconcile these discrepancies would be that the same prosurvival and anti-apoptotic properties of E 2 that are beneficial in the pressure-overloaded RV may contribute to increased pulmonary vascular wall cell proliferation and remodeling. While we did not note worsening PA remodeling with E 2 in our laboratory's prior studies of SuHx or chronically hypoxic rats (rather, we noted improvement) (11,32), E 2 may worsen PA remodeling in the context of genetic alterations in BMPR2 or serotonin signaling (2,43,44,63,64). E 2 may be "good for the RV" but, at least in certain contexts, "bad for the pulmonary vasculature" (31,34).…”

Translational Advances in the Field of Pulmonary Hypertension.Translating MicroRNA Biology in Pulmonary Hypertension. It Will Take More Than “miR” Words

“…PAH. A sex-specific decrease in miR-96 was found to increase expression of the 5-hydroxytryptamine 1B receptor (42), thus predisposing to alteration of serotonin signaling and proliferative signals in the diseased pulmonary vasculature. Separately, a sex-specific interaction of miR-29 was described with estrogen metabolism (43), suggesting a molecular mechanism correlating female hormone signaling with the predisposition of PAH in women in the general population.…”

Sex differences in pulmonary hypertension: are we cleaning up the mess?

“…For example, oestrogen appears to exert protective (e.g. vasodilator and anti-proliferative) effects in hypoxia-induced PH and MCT-PH [14,15], while it promotes pulmonary artery remodelling in the setting of BMPR2 mutations or increases in serotonin signalling [11,26]. Our laboratory demonstrated that oestrogen exerts anti-proliferative effects in the setting of hypoxia, but not during normoxia [14].…”