Disrupted PI3K subunit p110α signaling protects against pulmonary hypertension and reverses established disease in rodents
Eva M. Berghausen, … , Ralph T. Schermuly, Stephan Rosenkranz
Eva M. Berghausen, … , Ralph T. Schermuly, Stephan Rosenkranz
Published October 1, 2021
Citation Information: J Clin Invest. 2021;131(19):e136939. https://doi.org/10.1172/JCI136939.
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Disrupted PI3K subunit p110α signaling protects against pulmonary hypertension and reverses established disease in rodents

Abstract

Enhanced signaling via RTKs in pulmonary hypertension (PH) impedes current treatment options because it perpetuates proliferation and apoptosis resistance of pulmonary arterial smooth muscle cells (PASMCs). Here, we demonstrated hyperphosphorylation of multiple RTKs in diseased human vessels and increased activation of their common downstream effector phosphatidylinositol 3′-kinase (PI3K), which thus emerged as an attractive therapeutic target. Systematic characterization of class IA catalytic PI3K isoforms identified p110α as the key regulator of pathogenic signaling pathways and PASMC responses (proliferation, migration, survival) downstream of multiple RTKs. Smooth muscle cell–specific genetic ablation or pharmacological inhibition of p110α prevented onset and progression of pulmonary hypertension (PH) as well as right heart hypertrophy in vivo and even reversed established vascular remodeling and PH in various animal models. These effects were attributable to both inhibition of vascular proliferation and induction of apoptosis. Since this pathway is abundantly activated in human disease, p110α represents a central target in PH.

Authors

Eva M. Berghausen, Wiebke Janssen, Marius Vantler, Leoni L. Gnatzy-Feik, Max Krause, Arnica Behringer, Christine Joseph, Mario Zierden, Henrik ten Freyhaus, Anna Klinke, Stephan Baldus, Miguel A. Alcazar, Rajkumar Savai, Soni Savai Pullamsetti, Dickson W.L. Wong, Peter Boor, Jean J. Zhao, Ralph T. Schermuly, Stephan Rosenkranz

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Figure 4

Lack of p110α in smooth muscle cells attenuates growth factor–induced responses.

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Lack of p110α in smooth muscle cells attenuates growth factor–induced re...
(A) Expression of p110α and phosphorylation of AKT (Thr308) in pulmonary arteries from smooth muscle–specific p110α-deficient mice (sm-p110α–/–) compared with WT control mice (sm-p110α+/+) (3 repetitions). (B) Expression of the 3 catalytic class IA PI3K p110 subunits and the regulatory p85 subunit in murine PASMCs isolated from sm-p110α+/+, sm-p110α+/–, or sm-p110α–/– mice; α-actin shown as loading control (3 repetitions). (C–F) PDGF-BB–induced (n = 7 each) or growth factor mixture–induced (GFM-induced) proliferation (BrdU incorporation) (n = 5 each) and chemotaxis as indicated in PASMCs isolated from sm-p110α+/+, sm-p110α+/–, or sm-p110α–/– mice (n = 10, 10, 10, 3 and n = 9, 9, 4, 4). (G) Effects of hetero- and homozygous p110α deficiency on PDGF-BB (30 ng/mL) or GFM-dependent AKT (Thr308) phosphorylation in mPASMCs. RasGAP shown as a loading control. (H) Downstream signaling in mPASMCs isolated from WT (sm-p110α+/+) or homozygous p110α-deficient mice (sm-p110α–/–) left untreated or preincubated with PIK75 (300 nM) and stimulated with GFM for either 5 minutes (top panel) or 16 hours (bottom panel). RasGAP shown as loading control. Note that in contrast to WT cells stimulated with either PDGF or GFM, PIK75 did not further affect downstream signaling events in p110α-deficient PASMCs, indicating that PIK75 at the indicated concentration of 1 μM specifically inhibited p110α. (I) Apoptosis of serum-starved and PDGF-BB–treated mPASMCs isolated from sm-p110α+/+ or sm-p110α–/– mice (n = 5 each). All data (C–F and I) represent mean ± SEM, *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001 as assessed by 1-way ANOVA with Dunnett’s test.