Biology subjects

Troncone, L.

Publications and source records attributed to Troncone, L..

3 recordsLinked to original sources

bioRxiv2025

BMP9-mediated regulation of endothelin-1 requires integrated SMAD1/5 and SMAD2/3 signaling

BMP9 is a pleiotropic growth factor cytokine with diverse roles in vascular development, homeostasis and disease. BMP9 regulates a broad array of vasoactive molecules that mediate endothelial and mural cell function, including ET-1, a potent vasoconstrictor, regulator of cell growth and fibrosis, and therapeutic target for pulmonary arterial hypertension (PAH). Consistent with its pleiotropic activities, BMP9 is unique in being able to recruit both BMP-responsive SMAD1/5/9 and TGF{beta}-responsive SMAD2/3 signaling effectors in endothelial cells, however, the physiologic significance of activating both pathways remains incompletely defined. We investigated the role of SMAD1/5/9 vs. SMAD2/3 signaling in BMP9-mediated regulation of ET-1, using primary and immortalized human and murine microvascular endothelial cells, with conditional knockout, small molecule inhibitor and siRNA strategies. BMP9-mediated expression of ET-1 requires coordinated activation of SMAD1/5/9 and SMAD2/3 effector pathways, both downstream of BMPR2, ALK1, and ENG. Analysis of the ET-1 promoter revealed that BMP9 requires, in addition to a SMAD3/4 binding site sufficient for TGF{beta}1-mediated transcription, a novel putative SMAD1/5 binding motif. BMP9-mediated regulation of endothelial ET-1 requires coordinated activation of both SMAD1/5 and SMAD2/3 downstream of ALK1, integrated at the promoter level, representing a non-canonical signaling motif linking BMP9 to a critical effector of vascular tone and remodeling in PAH and related vascular syndromes. Translational PerspectiveBMP9 has recently emerged as a novel therapeutic target with an ongoing Phase 2 clinical trial testing an anti-BMP9 antibody for efficacy in PAH (NCT06137742). The mechanisms by which BMP9 contributes to pulmonary vascular disease are thought to include its regulation of Endothelin-1 (ET-1), an established therapeutic target in PAH. We show that BMP9 potently regulates ET-1 transcription via transactivation of TGF{beta}1 effector SMAD3 via BMP receptors BMPR2 and ALK1, suggesting that pleiotropic effects of this growth factor cytokine result from non-canonical activation of BMP and TGF{beta} signaling pathways, with implications for its roles in physiology, and the rationale for its therapeutic modulation for PAH.

cell biology↗

bioRxiv2025

BMP9 regulates the endothelial secretome to drive pulmonary hypertension

BMP9, a pleiotropic growth factor cytokine that regulates endothelial function, is implicated in the pathogenesis of pulmonary arterial hypertension (PAH). Loss-of-function mutations in GDF2 are found in heritable PAH, suggesting its function as an endothelial quiescence factor, while agonizing or antagonizing BMP9 signaling are both reported to ameliorate experimental pulmonary hypertension (PH). This study sought to resolve the contribution of BMP9 to pulmonary vascular disease and its status as a potential therapeutic target. The function of BMP9 in experimental PH was interrogated using recombinant BMP9, BMP9/BMP10 ligand trap ALK1-Fc, two anti-BMP9 neutralizing antibodies, and the activin/GDF/BMP ligand trap ACTRIIA-Fc (a.k.a., sotatercept). Disulfide-linked, prodomain complexed BMP9 was not protective in SUGEN-hypoxia or monocrotaline-induced PH models, in contrast to previous studies using incompletely disulfide-linked BMP9. In comparison, selective and non-selective BMP9 antagonism exerted prophylactic and therapeutic effects across PH models. Anti-BMP9 and ACTRIIA-Fc had comparable impact on hemodynamics, RV hypertrophy, and vascular remodeling, while single nucleus RNA-Seq revealed similar inhibition of SMAD1/5 and SMAD2/3 transcriptional activity, and highly overlapping DEGs, particularly in the endothelial compartment (r=0.83, p=2.54e-43, Spearman), suggesting overlap of mechanism in targeting BMP9. A multi-omic approach using lung tissues from human PAH, experimental models of pulmonary hypertension, and transcriptomic analysis of pulmonary microvascular endothelial cells from PAH patients revealed that BMP9 is critical for regulating several endothelial gene products that are overexpressed in human and experimental disease and implicated in disease pathogenesis including CXCL12, PDGF-BB, EDN1, COL18A1, and IGFBP4, and are inhibited by administering anti-BMP9 neutralizing antibodies or ligand traps. Co-culture studies revealed paracrine effects of BMP9-stimulated PMVEC on pulmonary arterial smooth muscle cell (PASMC) phenotypic plasticity, which could be attributed in large part to endothelial-derived CXCL12. In summary, endothelial BMP9 signaling is a key coordinator of vasoactive endothelial gene products that modulate PASMC phenotype and appears to be a shared target of anti-BMP9 and ACTRIIA-Fc. Selective targeting of endothelial BMP9 angiogenic signaling represents a potential therapeutic strategy for human PAH. One sentence summaryInhbiition of BMP9 signaling via different selective and non-selective strategies, including ACTRIIA-Fc/sotatercept, attenuates endothelial expression of vasoactive secreted factors that drive pulmonary vascular remodeling.

physiology↗

bioRxiv2021

ACVR1 antibodies exacerbate heterotopic ossification in fibrodysplasia ossificans progressiva (FOP) by activating FOP-mutant ACVR1

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder whose most debilitating pathology is progressive and cumulative heterotopic ossification (HO) of skeletal muscles, ligaments, tendons, and fascia. FOP is caused by mutations in the type I BMP receptor gene ACVR1, which enable ACVR1 to utilize its natural antagonist, Activin A, as an agonistic ligand. The physiological relevance of this property is underscored by the fact that HO in FOP is exquisitely dependent on activation of FOP-mutant ACVR1 by Activin A, an effect countered by inhibition of Activin A via monoclonal antibody treatment. Hence, we surmised that ACVR1 antibodies that block activation of ACVR1 by ligand should also inhibit HO in FOP and provide an additional therapeutic option for this condition. Therefore, we generated ACVR1 monoclonal antibodies that block ACVR1s activation by its ligands. Surprisingly, in vivo, these ACVR1 antibodies stimulate HO and activate signaling of FOP-mutant ACVR1. This property is restricted to FOP-mutant ACVR1 and results from ACVR1 antibody-mediated dimerization of ACVR1. Conversely, wild type ACVR1 is inhibited by ACVR1 antibodies. These results uncover an additional novel property of FOP-mutant ACVR1 and indicate that ACVR1 antibodies should not be considered as therapeutics for FOP.

biochemistry↗