Quilty, D. | bioRxiv Science

bioRxiv2025

Natural killer cell TGF- signaling regulates senolytic activity and vascular patterning in the postnatal lung

BackgroundBronchopulmonary dysplasia (BPD) is a disease of neonatal lung development that is linked to impaired pulmonary vascularization, dysregulated transforming growth factor-{beta} (TGF-{beta}) signaling and the accumulation of senescent cells. Despite the established role for TGF-{beta} signaling in promoting vascular remodeling and suppressing the senolytic activity of natural killer (NK) cells, the contribution of NK cell TGF-{beta} signaling to postnatal lung patterning and the pathogenesis of BPD remains unclear. MethodsMice bearing an NK cell-selective deletion of the type-II TGF-{beta} receptor (Tgfbr2NK-/-) were analyzed for vascular and alveolar structure, lung NK cell infiltration, senescence markers and lung function testing across neonatal and adult timepoints. Single-cell RNA sequencing of lung tissue from both neonatal mice and human infants with BPD was performed. The effect of enhanced NK cell activity in a hyperoxia-induced model of BPD was assessed in Tgfbr2NK-/-neonates, as well as pharmacologically, using the TGF-{beta} ligand trap/IL-15 superagonist, HCW9218. ResultsNeonatal Tgfbr2NK-/- mice exhibited a baseline reduction in distal arteriolar density, impaired alveolarization, and sex-specific deficits in long-term lung function. Single-cell RNA sequencing identified the excessive clearance of senescent endothelial cells by TGF-{beta} insensitive NK cells in the lungs of Tgfbr2NK-/- neonates, which served as a contributor of the BPD-like phenotype observed in naive animals. Tgfbr2NK-/- mice were protected from impaired lung development in the hyperoxia model. Sequencing from lung tissue from infants with BPD confirmed excessive TGF-{beta} signaling and cytotoxic impairment in NK cells. Treatment with HCW9218 prevented senescent cell accumulation and rescued lung development in the hyperoxia mouse model. ConclusionsThese findings identify TGF-{beta} as a tunable regulator of NK cell senolytic activity that is essential to normal postnatal lung development. Excessive NK cell TGF-{beta} signaling contributes to impaired lung development following exposure to neonatal hyperoxia and may serve as a viable therapeutic target for human BPD.

developmental biology↗

bioRxiv2023

Circular RNA profiling identifies circ5078 as a BMPR2-derived regulator of endothelial translation

Germline loss-of-function BMPR2 mutations are the leading genetic cause of pulmonary arterial hypertension (PAH) and are strongly linked to aberrant endothelial proliferation and impaired translational stress responses. While these effects are generally attributed to a loss of the type-II bone morphogenetic protein receptor (BMPR-II), we used circular RNA profiling to identify circ5078 as a new functional RNA derived from exon 12 of the BMPR2 gene. circ5078 and linear BMPR2 mRNA exert opposing effects on endothelial proliferation and stress granule formation, driving impaired stress responses in PAH patient-derived endothelial cells that are deficient in linear BMPR2 transcripts, but not circ5078. Rebalancing circular to linear transcript abundance by circ5078 depletion rescued stress granule formation in patient-derived endothelial cells, independent of BMPR-II protein levels. Polysome analysis demonstrated a reduction in free ribosomal subunits with the depletion of either linear or circular BMPR2 transcripts, and an accumulation of 80S monosomes exclusively with linear BMPR2 mRNA loss. These effects did not impact global protein synthesis or stress-induced eIF2 phosphorylation, but did alter the translational efficiency of multiple genes, including a group of nuclear encoded, mitochondrial ribosome proteins that were translationally enhanced with circ5078 silencing. Endothelial circ5078 depletion increased the efficiency of oxidative metabolism while reducing mitochondrial spare capacity, providing a potential link between mitochondrial function, proliferation and translational stress responses. Together, these findings reveal interdependent roles for linear and circular BMPR2 transcripts as functional contributors to the endothelial phenotype of PAH.

molecular biology↗