Abstract P3115: Disruption Of Assembly By Estrogen Limits Microtubule Proliferation In Failing Heart Cells

Abstract

Right heart failure, resulting from high pressure in the pulmonary artery, is the leading cause of mortality in pulmonary arterial hypertension (PAH). Interestingly, females with PAH have superior right ventricular (RV) function, which can mostly explain improved survival in female patients. Microtubules are long filaments that regulate cellular contractility and transport within cardiac cells. The excess proliferation of microtubules is associated with pathological t-tubule remodeling in failing RV cardiomyocytes. Previous work suggests that the female hormone estrogen disrupts microtubule assembly. Here, we explored whether estrogen treatment could ameliorate the pathological proliferation of microtubules. By utilizing iPSC-derived cardiomyocytes with live-cell confocal imaging, we show that estrogen treatment leads to long pausing during microtubule growth, like the microtubule inhibitor colchicine. Additionally, estrogen treatment rescues microtubule overgrowth in endothelin-stressed primary cardiomyocytes (Fig. 1). We examined the molecular mechanism using purified tubulin, the building block of microtubules, and estrogen. In cell-free experiments, estrogen induced long pauses in microtubule growth. Our preliminary data suggest that estrogen, like colchicine, binds to free tubulin and co-polymerizes with it, disrupting microtubule assembly independent of estrogen receptors. We conclude that estrogen’s ability to limit microtubule proliferation could contribute to sex differences in RV function in PAH. Figure 1: Primary cardiomyocytes. Microtubule proliferation in endothelin-treated cells was rescued with estradiol.