Biology subjects

Sun, Y. L.

Publications and source records attributed to Sun, Y. L..

6 recordsLinked to original sources

bioRxiv2026

Glucocorticoids reprogram human AML leukemic stem cells to promote elimination through differentiation and apoptosis

Acute myeloid leukemia (AML) is sustained by leukemic stem cells (LSCs) that can evade standard therapies and drive relapse. Targeting LSC-specific vulnerabilities is therefore essential for durable remission. Here we demonstrate that glucocorticoids (GCs) induce potent depletion of AML LSCs by promoting terminal differentiation and apoptosis. This effect is observable within 24 hours and is conserved across multiple LSC-enriched models and primary patient samples. Mechanistically, we establish that GC targeting of LSCs is mediated through the glucocorticoid receptor (NR3C1), with higher receptor binding affinity correlating with greater anti-LSC activity. We performed structure activity relationship (SAR) modeling of 24 corticosteroids and identified key features, including bulky D-ring substituents, associated with enhanced anti-LSC efficacy. Bulk and single-cell transcriptomic data revealed that GC treatment of LSCs suppresses NF-{kappa}B inflammatory signaling and disrupts stemness and quiescence programs while inducing transcriptional signatures associated with transient proliferation, metabolic stress, and terminal differentiation. Notably, GC sensitivity was associated with the expression of pre-existing inflammatory or extracellular matrix (ECM) signatures. Finally, we found that FLT3 ligand (FLT3L) is required for GC-induced proliferation of CD34- blasts but not for LSC depletion, suggesting that FLT3L levels may serve as a biomarker for blast expansion in patients receiving GC therapy. These findings support the clinical development of GC-based therapies in AML and provide mechanistic insights into how GCs target inflammatory and metabolic programs required for LSC survival.

cancer biology↗

bioRxiv2026

Hemodynamic Responses in the White Matter (WM): Reduced Blood Flow in Deep WM During Hypercapnia Revealed by Multi-Delay pCASL in Healthy Young Adults

The white matter (WM) cerebrovascular response remains poorly understood compared with grey matter (GM), partly due to technical challenges in perfusion quantification. Previous studies of cerebrovascular reactivity (CVR) have mostly been performed using BOLD MRI, and it is unclear to what extent they reflect changes in cerebral blood flow (CBF). In this work, we used multi-delay pseudo-continuous arterial spin labeling (pCASL) to quantify hypercapnia-induced CBF changes ({Delta}CBF) while accounting for regional variability in arterial transit time. Twenty-five healthy young adults underwent MRI during normocapnia and hypercapnia (inhalation of a 4% CO2 gas mixture). Hypercapnia induced robust positive {Delta}CBF in cortical GM (26.7 {+/-} 13.5%), superficial WM (17.2 {+/-} 12.6%), periventricular regions (13.6 {+/-} 10.6%), and subcortical GM (25.7 {+/-} 14.1%) (all p < 0.0001). In contrast, deep WM exhibited a near-zero group-mean CBF response (1.0 {+/-} 8.9%, p = 0.57), with 10 of 25 participants demonstrating negative {Delta}CBF. Negative CBF responses were consistently localized to the corona radiata, centrum semiovale, and optic radiation. Quality-control analyses showed that deep-WM {Delta}CBF estimates are robust, supporting the reliability of these findings. Moreover, across tissue compartments, higher baseline CBF was associated with reduced hypercapnic responsiveness, and deep-WM responses were strongly coupled with cortical GM responses across individuals. These results demonstrate that hypercapnia-induced cerebrovascular responses are highly heterogeneous across tissue depths and provide evidence that negative CBF responses can occur in healthy deep WM in the presence of vasodilation elsewhere. The findings challenge the assumption of uniformly positive perfusion responses during hypercapnia and support a potential role for flow redistribution arising from regional differences in vascular resistance and reserve capacity.

neuroscience↗

bioRxiv2024

Developmental order, fibre caliber, and vascularization predict tract-wise declines: Testing retrogenesis and physiological predictions in white matter aging

To understand the consistently observed spatial distribution of white-matter (WM) aging, developmentally driven theories termed "retrogenesis" have gained traction, positing that the order of WM tract development predicts the order of declines. Regions that develop first are expected to deteriorate the last, i.e. "last-in-first-out". Alternatively, regions which develop most rapidly may also decline most rapidly in aging, or "gains-predict-loss". The validity of such theories remains uncertain, in part due to lack of clarity on the definition of developmental order. Importantly, our recent findings suggest that WM aging is also associated with physiological parameters such as perfusion, which may be linked to fibre metabolic need, which in turn varies with fibre size. Here we address the extent to which the degree of WM aging is determined by development trajectory (i.e. retrogenesis) and/or by physiological state. We obtained microstructural and perfusion measures using data from the Human Connectome Project in Aging (HCP-A), complemented by a meta-analysis involving maps of fibre calibre and macrovascular volume. Our results suggest that (1) while tracts that appear last or finish myelinating first in development display the slowest aging, the pattern of aging is not fully explained by retrogenesis; in fact, time courses of tract emergence and myelination give rise to opposite associations with WM decline; (2) tracts that appear earlier also have higher mean axon calibre and are also associated with lower degrees of WM microstructural aging; (3) such tracts also tend to exhibit relatively sustained CBF with a higher rate of lengthening of the arterial transit times (ATT), suggestive of collateral blood supply. These findings were also sex dependent in a tract-specific manner. Future work will investigate whether these are ultimately influenced by each tracts metabolic demand and the role of macrovascular collateral flow.

neuroscience↗

bioRxiv2023

In search of a unifying theory of white matter aging: tract perfusion-microstructure relationships

One of the most promising interventional targets for brain health is cerebral perfusion, but its link to white matter (WM) aging remains unclear. Motivated by existing literature demonstrating links between declining cortical perfusion and the development of WM hyperintensities, we posit that regional WM hypoperfusion precedes deteriorating WM integrity. Using the Human Connectome Project Aging (HCP-A) data set, we examine tract-wise associations between WM microstructural integrity (i.e. fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity) and perfusion (i.e. cerebral blood flow and arterial transit time) in ten major bilateral WM tracts. Results show that tracts displaying the largest CBF decline in aging do not necessarily display the largest ATT decline, and vice versa. Moreover, significant WM perfusion-microstructure canonical correlations were found in all tracts, but the drivers of these correlations vary by both tract and sex, with female subjects demonstrating more tracts with large microstructural variations contributing to the correlations. Additionally, arterial transit time appears to be the earliest indicator of WM declines, preceding age-related microstructural differences and CBF in several tracts. This study contributes compelling evidence to the vascular hypothesis of WM degeneration, and highlights the utility of blood-flow timing as an early marker of aging.

neuroscience↗

bioRxiv2023

In search of a unifying theory of white matter aging: tract morphometry-microstructure relationships

While tract-wise differences in volume and microstructure are common targets of investigation in age-related changes in the white matter (WM), there has been relatively little exploration into other attributes of tract morphometry or its relation to microstructure in vivo, and limited understanding on how they jointly inform the interpretation of the WM aging trajectory. This study examines ten WM tracts for tract-wise differences in morphometry (i.e. volume, length, and volume-to-length ratio) and microstructural integrity (i.e. fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity) using diffusion MRI data from the Human Connectome Project in Aging (HCP-A) with the goal of laying the foundation for a unified model of age-related WM microstructure-morphometry trajectories with a special focus on sex differences. Results indicated widely heterogeneous patterns of decline and morphometry-microstructural associations across tracts. Multi-parametric signatures of decline suggest stages or mechanisms of degeneration that differ between sexes. This work highlights the value of integrating microstructural and morphometric measures of WM health instead of observing them separately, suggesting multiple modes of WM degeneration.

neuroscience↗

bioRxiv2019

Single-cell time-series mapping of cell fate trajectories reveals an expanded developmental potential for human PSC-derived distal lung progenitors

Alveolar epithelial type 2 cells (AEC2s) are the facultative progenitors responsible for maintaining lung alveoli throughout life, yet are difficult to access from patients for biomedical research or lung regeneration applications. Here we engineer AEC2s from human induced pluripotent stem cells (iPSCs) in vitro and use single cell RNA sequencing (scRNA-seq) to profile the detailed kinetics of their differentiation over time. We focus on both the desired target cells as well as those that appear to diverge to alternative endodermal fates. By combining scRNA-seq with lentiviral barcoding to trace differentiating clones, we reveal the bifurcating cell fate trajectories followed as primordial lung progenitors differentiate into mature AEC2s. We define the global transcriptomic signatures of primary developing human AEC2s from fetal through adult stages in order to identify the subset of in vitro differentiating cells that appear to recapitulate the path of in vivo development. In addition, we develop computational methods based on Continuous State Hidden Markov Models (CSHMM) to identify the precise timing and type of signals, such as over-exuberant Wnt responses, that induce some early multipotent NKX2-1+ progenitors to lose lung fate as they clonally diverge into a variety of non-lung endodermal lineages. Finally, we find that this initial developmental plasticity is regulatable via Wnt modulation, and subsides over time, ultimately resulting in iPSC-derived AEC2s that exhibit a stable phenotype and nearly limitless self-renewal capacity in vitro. Our methods and computational approaches can be widely applied to study and control directed differentiation, producing an inexhaustible supply of mature lineages, exemplified here by the generation of AEC2s.

developmental biology↗