Lai Ying-Ju, Chang Gwo-Jyh, Yeh Yung-Hsin, Pang Jong-Hwei S, Huang Chung-Chi, Chen Wei-Jan
Department of Respiratory Therapy, Chang Gung University College of Medicine, Chang-Gung University, Tao-Yuan, Taiwan.
Graduate Institute of Clinical Medical Sciences, Chang Gung University College of Medicine, Chang-Gung University, Tao-Yuan, Taiwan.
PLoS One. 2015 Sep 14;10(9):e0137426. doi: 10.1371/journal.pone.0137426. eCollection 2015.
Gamma-secretase-mediated Notch3 signaling is involved in smooth muscle cell (SMC) hyper-activity and proliferation leading to pulmonary arterial hypertension (PAH). In addition, Propylthiouracil (PTU), beyond its anti-thyroid action, has suppressive effects on atherosclerosis and PAH. Here, we investigated the possible involvement of gamma-secretase-mediated Notch3 signaling in PTU-inhibited PAH. In rats with monocrotaline-induced PAH, PTU therapy improved pulmonary arterial hypertrophy and hemodynamics. In vitro, treatment of PASMCs from monocrotaline-treated rats with PTU inhibited their proliferation and migration. Immunocyto, histochemistry, and western blot showed that PTU treatment attenuated the activation of Notch3 signaling in PASMCs from monocrotaline-treated rats, which was mediated via inhibition of gamma-secretase expression especially its presenilin enhancer 2 (Pen-2) subunit. Furthermore, over-expression of Pen-2 in PASMCs from control rats increased the capacity of migration, whereas knockdown of Pen-2 with its respective siRNA in PASMCs from monocrotaline-treated rats had an opposite effect. Transfection of PASMCs from monocrotaline-treated rats with Pen-2 siRNA blocked the inhibitory effect of PTU on PASMC proliferation and migration, reflecting the crucial role of Pen-2 in PTU effect. We present a novel cell-signaling paradigm in which overexpression of Pen-2 is essential for experimental pulmonary arterial hypertension to promote motility and growth of smooth muscle cells. Propylthiouracil attenuates experimental PAH via suppression of the gamma-secretase-mediated Notch3 signaling especially its presenilin enhancer 2 (Pen-2) subunit. These findings provide a deep insight into the pathogenesis of PAH and a novel therapeutic strategy.
γ-分泌酶介导的Notch3信号通路参与平滑肌细胞（SMC）的过度活跃和增殖，进而导致肺动脉高压（PAH）。此外，丙硫氧嘧啶（PTU）除了具有抗甲状腺作用外，还对动脉粥样硬化和PAH具有抑制作用。在此，我们研究了γ-分泌酶介导的Notch3信号通路在PTU抑制PAH中的可能作用。在使用野百合碱诱导PAH的大鼠中，PTU治疗改善了肺动脉肥厚和血流动力学。在体外，用PTU处理野百合碱处理的大鼠的肺动脉平滑肌细胞（PASMCs）可抑制其增殖和迁移。免疫细胞化学、组织化学和蛋白质印迹显示，PTU处理减弱了野百合碱处理的大鼠PASMCs中Notch3信号通路的激活，这是通过抑制γ-分泌酶表达，尤其是其早老素增强子2（Pen-2）亚基介导的。此外，在对照大鼠的PASMCs中过表达Pen-2可增加迁移能力，而在野百合碱处理的大鼠的PASMCs中用其相应的小干扰RNA（siRNA）敲低Pen-2则产生相反的效果。用Pen-2 siRNA转染野百合碱处理的大鼠的PASMCs可阻断PTU对PASMC增殖和迁移的抑制作用，这反映了Pen-2在PTU作用中的关键作用。我们提出了一种新的细胞信号传导模式，其中Pen-2的过表达对于实验性肺动脉高压促进平滑肌细胞的运动性和生长至关重要。丙硫氧嘧啶通过抑制γ-分泌酶介导的Notch3信号通路，尤其是其早老素增强子2（Pen-2）亚基，减轻实验性PAH。这些发现为PAH发病机制提供了深入见解，并提出了一种新的治疗策略。
