PPARγ-p53-Mediated Vasculoregenerative Program to Reverse Pulmonary Hypertension

Abstract

Rationale: In pulmonary arterial hypertension (PAH), endothelial dysfunction and obliterative vascular disease are associated with DNA damage and impaired signaling of BMPR2 (bone morphogenetic protein type 2 receptor) via two downstream transcription factors, PPARγ (peroxisome proliferator-activated receptor gamma), and p53. Objective: We investigated the vasculoprotective and regenerative potential of a newly identified PPARγ-p53 transcription factor complex in the pulmonary endothelium. Methods and Results: In this study, we identified a pharmacologically inducible vasculoprotective mechanism in pulmonary arterial and lung MV (microvascular) endothelial cells in response to DNA damage and oxidant stress regulated in part by a BMPR2 dependent transcription factor complex between PPARγ and p53. Chromatin immunoprecipitation sequencing and RNA-sequencing established an inducible PPARγ-p53 mediated regenerative program regulating 19 genes involved in lung endothelial cell survival, angiogenesis and DNA repair including, EPHA2 ( ephrin type-A receptor 2 ), FHL2 ( four and a half LIM domains protein 2 ), JAG1 ( jagged 1 ), SULF2 ( extracellular sulfatase Sulf-2 ), and TIGAR ( TP53-inducible glycolysis and apoptosis regulator ). Expression of these genes was partially impaired when the PPARγ-p53 complex was pharmacologically disrupted or when BMPR2 was reduced in pulmonary artery endothelial cells (PAECs) subjected to oxidative stress. In endothelial cell-specific Bmpr2 -knockout mice unable to stabilize p53 in endothelial cells under oxidative stress, Nutlin-3 rescued endothelial p53 and PPARγ-p53 complex formation and induced target genes, such as APLN ( apelin ) and JAG1 , to regenerate pulmonary microvessels and reverse pulmonary hypertension. In PAECs from BMPR2 mutant PAH patients, pharmacological induction of p53 and PPARγ-p53 genes repaired damaged DNA utilizing genes from the nucleotide excision repair pathway without provoking PAEC apoptosis. Conclusions: We identified a novel therapeutic strategy that activates a vasculoprotective gene regulation program in PAECs downstream of dysfunctional BMPR2 to rehabilitate PAH PAECs, regenerate pulmonary microvessels, and reverse disease. Our studies pave the way for p53-based vasculoregenerative therapies for PAH by extending the therapeutic focus to PAEC dysfunction and to DNA damage associated with PAH progression.

Vascular Endothelial Cells: Heterogeneity and Targeting Approaches

“…Pulmonary arterial and arteriolar ECs also feature a distinct phenotype related to archaic/conserved stress response pathways. While the activation of the tumor suppressor p53 initiates a vasculoregenerative program in pulmonary arterial and arteriolar ECs [91,92], in other vascular systems, endothelial p53 was detrimental to vascular regeneration and homeostasis [93][94][95]. The exact underlying mechanisms for a distinct response of a single transcription factor such as p53, e.g., organspecific interaction partners, dose-response effects or chromatin accessibility, remain the focus of ongoing investigations [91,96].…”

Monolith/Hydrogel composites as triamcinolone acetonide carriers for curing corneal neovascularization in mice by inhibiting the fibrinolytic system

“…Previous studies have indicated that HIF-1 signaling pathway seems to participate in vascular formation by synergistic correlations with other proangiogenic factors such as VEGF, placental growth factor, or angiopoietins (Iwase et al., 2013 ; Xu et al., 2018 ; Wen et al., 2019 ). PPAR signaling pathways were highly correlated with the expression of the genes involved in inflammation (Calvier et al., 2019 ; Hennigs et al., 2021 ). The specific mechanism may be realized by the synergistic effect with the co-activator of nuclear receptor after the initial activation and heterodimerization of PPARs (Gong et al., 2016 ).…”

Therapeutic Approaches for Treating Pulmonary Arterial Hypertension by Correcting Imbalanced TGF-β Superfamily Signaling

“…Additional agents have been evaluated preclinically as therapeutic activators of downstream targets in the SMAD1/5/8 pathway. One is nutlin-3, a small molecule which stabilizes a BMPRII-dependent transcription factor complex between p53 and PPARγ (peroxisome proliferator-activated receptor gamma) to activate a vasculoprotective gene regulation program downstream of BMPRII that includes the apelin gene ( APLN ) ( 127 ). This approach has been used to regenerate pulmonary microvessels and reverse persistent PH in mice with loss of BMPRII in pulmonary arterial ECs ( 127 ).…”

“…One is nutlin-3, a small molecule which stabilizes a BMPRII-dependent transcription factor complex between p53 and PPARγ (peroxisome proliferator-activated receptor gamma) to activate a vasculoprotective gene regulation program downstream of BMPRII that includes the apelin gene ( APLN ) ( 127 ). This approach has been used to regenerate pulmonary microvessels and reverse persistent PH in mice with loss of BMPRII in pulmonary arterial ECs ( 127 ). Another therapeutic agent that can promote expression of BMPRII pathway effectors is tyrphostin-AG1296, a small-molecule tyrosine kinase inhibitor identified by screening compounds for improved survival of ECs from PAH patients ( 148 ).…”