Biology subjects

Young, L. R.

Publications and source records attributed to Young, L. R..

8 recordsLinked to original sources

bioRxiv2026

A Single-Cell Atlas of PVOD Across the Lifespan Reveals Cellular and Molecular Therapeutic Targets

Rationale Pulmonary veno-occlusive disease (PVOD) is a progressive and lethal disease cured only lung transplant. While genetic mutations in EIF2AK4 have been identified in some cases, 70% of PVOD patients have no known etiology. Objectives To construct a single-cell atlas to define the cellular and molecular constituents driving pathophysiology in PVOD. Methods Lung samples were collected from four idiopathic non-EIF2AK4 mutation pediatric and adult PVOD patients and age-matched controls. Analyses of single-cell RNA sequencing, Xenium spatial transcriptomics, and immunohistochemistry were performed to identify cell state changes and differential gene expression between controls and PVOD and subsequent transcriptome comparison between our PVOD and published pulmonary arterial hypertension (PAH) datasets. Measurement and Main Results The single-cell atlas reveals marked changes in the PVOD endothelium compared to controls. EndMT and ectopic COL15A1+ systemic venous shunts and pulmonary vein endothelium are hallmarks of PVOD. Molecular analyses reveal activation of the integrated stress response (ISR)/ATF4, TGF{beta} signaling, MAPK signaling, and BRD4 are potential key players in the pathophysiology of PVOD. While PVOD and PAH share both pathological and some molecular mechanisms, ISR and TGF{beta} signaling are more prominent in PVOD than PAH. Conclusions These data indicate that endothelial dysfunction is a primary etiology in the development of PVOD with activation of multiple pathways with druggable targets.

molecular biology↗

bioRxiv2026

A postnatal human lung developmental atlas reveals windows of genetic vulnerability to chronic lung disease

At birth, the lungs undergo an abrupt physiologic change, as the function of gas exchange transitions from the placenta to the lung. Subsequent postnatal development of the lungs is marked by a rapid and profound increase in the growth of the distal airways and alveolar gas exchange compartment. Insults during this period increase the risk of developing lung disease later in life, though how early-life events affect adult disease onset remains unclear. We generated a single-cell atlas of postnatal human lung development from birth through adulthood and mapped temporally regulated gene expression changes in each cell lineage. Using this atlas, we identified disease risk-associated genes with developmentally regulated expression. These analyses reveal cell type-specific and temporally restricted expression of genes associated with adult lung disease risk, including COPD. Heritability enrichment analysis demonstrated that COPD genetic risk is enriched in genes active during early postnatal endothelial development, linking early-life vascular maturation to adult disease susceptibility. These findings characterize the early window of susceptibility for adult chronic lung diseases and establish a framework to guide mechanistic studies of disease-associated genes.

developmental biology↗

bioRxiv2023

Dynamic Hippo pathway activity underlies mesenchymal differentiation during lung alveolar morphogenesis

Alveologenesis, the final stage in lung development, substantially remodels the distal lung, expanding the alveolar surface area for efficient gas exchange. Secondary crest myofibroblasts (SCMF) exist transiently in the neonatal distal lung and are critical for alveologenesis. However, the pathways that regulate SCMF function, proliferation, and temporal identity remain poorly understood. To address this, we purified SCMFs from reporter mice, performed bulk RNA-sequencing, and found dynamic changes in Hippo-signaling components during alveologenesis. We deleted Hippo effectors, Yap/Taz, from Acta2-expressing SCMFs at the onset of alveologenesis, causing a significant arrest in alveolar development. Using scRNA-seq, we identified a distinct cluster of cells in mutant lungs with altered expression of marker genes associated with proximal mesenchymal cell types, airway smooth muscle (ASM), and alveolar duct myofibroblasts (DMF). Using lineage tracing, we show that neonatal Acta2-expressing SCMFs give rise to adult DMFs and that Yap/Taz mutants have an increase of persisting DMF-like cells in the alveolar ducts. Our findings identify plasticity in neonatal lung myofibroblasts and demonstrate that Yap/Taz are critical for maintaining lineage commitment along the proximal-distal axis.

developmental biology↗

bioRxiv2023

Transcriptional profiling of peripheral blood mononuclear cells identifies inflammatory phenotypes in ataxia telangiectasia

Ataxia telangiectasia (A-T) is an autosomal recessive neurodegenerative disease with widespread systemic manifestations and marked variability in clinical phenotypes. In this study, we sought to determine whether transcriptomic profiling of peripheral blood mononuclear cells defines subsets of individuals with A-T beyond mild and classic phenotypes, enabling identification of novel features for disease classification and treatment response to therapy. MethodsParticipants with stable A-T (n=90) were recruited and compared with unaffected controls (n=15). PBMCs were isolated and bulk RNAseq was performed. Plasma was also isolated in a subset of individuals. Affected individuals were designated mild or classic based on ATM mutations and clinical and laboratory features. ResultsPeople with classic A-T were more likely to be younger and IgA deficient and to have higher alpha-fetoprotein levels and lower % forced vital capacity compared to individuals with mild A-T. In classic A-T, the expression of genes required for V(D)J recombination was lower, and the expression of genes required for inflammatory activity was higher. We assigned inflammatory scores to study participants and found that inflammatory scores were highly variable among people with classic A-T and that higher scores were associated with lower ATM mRNA levels. Using a cell type deconvolution approach, we inferred that CD4+ T cells and CD8+ T cells were lower in number in people with classic A-T. Finally, we showed that individuals with classic A-T exhibit higher SERPINE1 (PAI-1) mRNA and plasma protein levels, irrespective of age, and higher FLT4 (VEGFR3) and IL6ST (GP130) plasma protein levels compared with mild A-T and controls. ConclusionUsing an unbiased transcriptomic approach, we identified novel features and developed an inflammatory score to identify subsets of individuals with different inflammatory phenotypes in A-T. Findings from this study could be used to help direct treatment and to track treatment response to therapy.

immunology↗

bioRxiv2023

Dysregulated alveolar epithelial maintenance in Hermansky-Pudlak syndrome pulmonary fibrosis

Hermansky-Pudlak syndrome (HPS) is a genetic disorder of endosomal protein trafficking associated with pulmonary fibrosis in specific subtypes, including HPS-1 and HPS-2. Single mutant HPS1 and HPS2 mice display increased fibrotic sensitivity while double mutant HPS1/2 mice exhibit spontaneous fibrosis with aging, which has been attributed to HPS mutations in alveolar epithelial type II (AT2) cells. We utilized HPS mouse models and human lung tissue to investigate mechanisms of AT2 cell dysfunction driving fibrotic remodeling in HPS. Starting at 8 weeks of age, HPS mice exhibited progressive loss of AT2 cell numbers. HPS AT2 cell function was impaired ex vivo and in vivo. Incorporating AT2 cell lineage tracing in HPS mice, we observed aberrant differentiation with increased AT2-derived alveolar epithelial type I cells. Transcriptomic analysis of HPS AT2 cells revealed elevated expression of genes associated with aberrant differentiation and p53 activation. Lineage tracing and organoid modeling studies demonstrated that HPS AT2 cells were primed to persist in a Krt8+ reprogrammed transitional state, mediated by p53 activity. Intrinsic AT2 progenitor cell dysfunction and p53 pathway dysregulation are novel mechanisms of disease in HPS-related pulmonary fibrosis, with the potential for early targeted intervention before the onset of fibrotic lung disease.

cell biology↗

bioRxiv2023

Endodermal BRD4 mediates epithelial-mesenchymal crosstalk during lung development

Lung morphogenesis relies on diverse cell intrinsic and extrinsic mechanisms to ensure proper cellular differentiation and compartmentalization. Using genetic mouse models, tissue explants, and transcriptomic analysis, we demonstrate that the epigenetic reader Bromodomain Containing Protein 4 (BRD4) is required for lung morphogenesis and perinatal survival. Endodermal BRD4 deletion impairs epithelial-mesenchymal crosstalk, leading to disrupted proximal-distal patterning and branching morphogenesis. These early defects result in dilated airways and the formation of cystic distal airway structures, containing both airway and alveolar features. Moreover, BRD4 deficient lungs exhibit abnormal airway and alveolar epithelial cell lineage allocation and differentiation. Restoration of SHH signaling partially rescues defects due to loss of BRD4, suggesting a role for BRD4 in regulating the SHH-FGF signaling axis. Together, these data identify the essential role of Brd4 in lung development to ensure proper intercellular crosstalk to enable proper lineage specification, identity, and maturation.

developmental biology↗

bioRxiv2022

A CXCL12 morphogen gradient uncovers lung endothelial heterogeneity and promotes distal vascular growth

In adults, there is a growing amount of data uncovering the cellular diversity of the pulmonary circulation and mechanisms governing vascular repair after injury, however, molecular and cellular mechanisms contributing to the morphogenesis and growth of the pulmonary vasculature during embryonic development are less clear. Importantly, deficits in vascular development lead to a large number of lung diseases in children, indicating a need to uncover fetal programs that promote pulmonary vascular growth. To address this, we used a transgenic mouse reporter for expression of Cxcl12, an arterial hallmark gene, and performed single-cell RNA sequencing on isolated Cxcl12-DsRed+ endothelium to assess cellular heterogeneity within pulmonary endothelium. Combining cell annotation, gene ontology analysis, and spatial transcriptomics allowed us to segregate the developing artery into spatially and functionally distinct novel subpopulations. In addition, expression of Cxcl12 suggests a morphogen gradient from arteries to capillaries, suggesting directed cell migration for pulmonary vascular development. Disruption of this gradient led to abnormal branching and pulmonary vascular hypoplasia. These data provide evidence for arterial endothelial functional heterogeneity and reveal conserved signaling mechanisms essential for pulmonary vascular development.

developmental biology↗

bioRxiv2017

Hypoosmolar dose-dependent swelling occurs in both pyramidal neurons and astrocytes in acute hippocampal slices

Normal nervous system function is critically dependent on the balance of water and ions in the extracellular space. Pathological reduction in brain interstitial osmolarity results in osmotically-driven flux of water into cells, causing cellular edema which reduces the extracellular space and increases neuronal excitability and risk of seizures. Astrocytes are widely considered to be particularly susceptible to cellular edema due to selective expression of the water channel aquaporin-4 (AQP4). The apparent resistance of pyramidal neurons to osmotic swelling has been attributed to lack of functional water channels. In this study we report rapid volume changes in CA1 pyramidal cells in hypoosmolar ACSF (hACSF) that are equivalent to volume changes in astrocytes across a variety of conditions. Astrocyte and neuronal swelling was significant within 1 minute of exposure to 17 or 40% hACSF, was rapidly reversible upon return to normosmolar ACSF, and repeatable upon re-exposure to hACSF. Neuronal swelling was not an artifact of patch clamp, occurred deep in tissue, was similar at physiological vs. room temperature, and occurred in both juvenile and adult hippocampal slices. Neuronal swelling was neither inhibited by TTX, nor by antagonists of NMDA or AMPA receptors, suggesting that it was not occurring as a result of excitotoxicity. Surprisingly, genetic deletion of AQP4 did not inhibit, but rather augmented, astrocyte swelling in severe hypoosmolar conditions. Taken together, our results indicate that neurons are not osmoresistant as previously reported, and that osmotic swelling is driven by an AQP4-independent mechanism.

neuroscience↗