Biology subjects

Greco, V.

Publications and source records attributed to Greco, V..

At least 19 recordsLinked to original sources

bioRxiv2026

A mitochondrial program encodes brain vascular reserve

Brain resilience depends on collateral vessels whose geometries preserve blood flow when primary arteries are perturbed. How these protective vascular architectures are developmentally established remains unknown. Using longitudinal in vivo imaging in zebrafish, we show that mitochondrial state in embryonic angiogenic tip cells encodes the topology of basal and surface brain collateral networks. Mechanistically, microRNA-125a establishes the bioenergetic and redox balance of endothelial tip-cell mitochondria through conserved repression of the metabolic regulator PGC1a. Disruption of the microRNA-125a-PGC1a axis uncouples mitochondrial capacity from redox buffering in developing brain tip cells, redirecting their migration toward sparse, incompletely connected collateral network topologies and increasing adult cerebrovascular vulnerability. Consistent with this mechanism, humans with subclinical cerebrovascular injury exhibit reduced circulating microRNA-125a levels associated with incomplete basal collateral configurations. Together, these findings identify mitochondrial state as an instructive and conserved developmental program that encodes brain vascular reserve.

developmental biology↗

bioRxiv2025

Skin capillary endothelial cells form a network of spatiotemporally conserved Ca2+ activity

Ca2+ signaling and its regulation are important for endothelial cell (EC) function and signaling. Yet, the spatiotemporal organization of Ca2+ activity and its regulation across a vascular plexus is poorly understood in an in vivo mammalian context. To overcome this gap in knowledge, we developed an intravital imaging approach to resolve Ca2+ activity with single cell resolution in skin vasculature of adult mice via multiphoton microscopy. Here, we tracked thousands of Ca2+ events in the skin capillary plexus during homeostasis and observed signaling heterogeneity between ECs, with just over half displaying Ca2+ activity at any given time. Longitudinal tracking of the same mice revealed that the same capillary ECs maintain Ca2+ activity over days to weeks. Interestingly, activity dynamics, such as frequency and event duration, are not conserved at a single cell level but are maintained at an EC population level. Molecularly, conditional deletion of the gap junction protein Connexin 43 (Cx43cKO) in ECs lead to a subset of ECs displaying sustained Ca2+ activity, biasing signaling dynamics of the whole network towards chronically persistent activity over time. Sustained capillary Ca2+ activity resulted in vascular permeability and flow dysregulation. Lastly, through pharmacological targeting of known agonists/antagonists, we showed that inhibition of L-type Voltage Gated Ca2+ channels (VGCCs) non cell-autonomously restores Ca2+ activity, blood flow, and barrier function in Cx43cKO mice. Collectively, our work provides insight into the characteristics, extent, and regulation of Ca2+ activity in skin capillaries of live mice with unprecedented spatial and temporal resolution. Significance StatementCa2+ signaling in mammalian endothelial cells (ECs) locally regulates blood flow, force sensing, and vessel permeability. Past studies have investigated Ca2+ signaling during vascular remodeling and repair. However, there is a gap in our understanding of how tissue-level Ca2+ is spatiotemporally organized and regulated during homeostasis. Intravital imaging in skin vasculature of live mice reveals that a conserved network of ECs participates in tissue-wide Ca2+ signaling over weeks. How this network maintains itself over time requires cellular communication through gap junction protein Connexin 43 (Cx43). Loss of EC Cx43 leads to heightened plexus-wide Ca2+ activity, and vessel barrier and flow dysregulation. Inhibition of L-type Ca2+ channels non-cell autonomously restores the capillary Ca2+ landscape, and rescues both barrier and flow dysfunction.

developmental biology↗

bioRxiv2025

Fibroblast depletion reveals mammalian epithelial resilience across neonatal and adult stages

Regenerative organs, like the skin, depend on niche-stem cell interactions that sustain continuous cellular turnover. In cell culture, skin fibroblasts promote epidermal stem cell proliferation and differentiation. Yet, it remains elusive how fibroblasts regulate epidermal stem cell behaviors and differentiation in skin in vivo. Here, we asked how fibroblast depletion may impact epidermal stem cell proliferation in the context of adult homeostasis. Surprisingly, we find that significant depletion of fibroblast density does not affect epidermal stem cell proliferative capacity during adult stages in vivo. We next probed earlier neonatal stages when skin is actively remodeling but found no change in epidermal stem cell proliferative capacity following fibroblast depletion. These results demonstrate that across different ages, epidermal stem cell proliferative capacity can persist in the face of a largely reduced fibroblast population. Interestingly, neonatal fibroblast depletion does not significantly reduce their secreted collagen I density but affects basement membrane mechanics and epidermal stem cell delamination. Despite these changes, the skin continues to maintain its protective barrier function. Thus, our work demonstrates the skin regenerative program employs robust compensatory mechanisms in the face of fibroblast depletion to maintain functional capacity.

cell biology↗

bioRxiv2024

Disarming emotional memories using Targeted Memory Reactivation during Rapid Eye Movement sleep

Emotional responses are dampened across sleep, and this is thought to be mediated by neural reactivation during Rapid Eye Movement (REM) Sleep. Such reactivation can be triggered by targeted memory reactivation (TMR), a technique in which a tone previously associated with a memory during wake is re-presented during subsequent sleep. Prior work has shown that TMR in REM reduces arousal responses to negative stimuli. The present study builds on this by measuring autonomic responses and brain activity as well as behaviour. Participants rated the arousal of 48 affective images, paired with semantically matching sounds. Half of these sounds were cued during REM in the subsequent overnight sleep cycle. Participants rated the images in a Magnetic Resonance Imaging (MRI) scanner with pulse oximetry 48 hours after encoding, and again after two weeks. Results showed that TMR during REM was also associated with reduced brain activity in the two primary nodes of the Salience Network (SN): the Anterior Insula and dorsal Anterior Cingulate Cortex (dACC), as well as the orbitofrontal cortex, subgenual cingulate, and left amygdala, all of which are known to be important for emotional processing. TMR markedly reduced the emotional heart rate deceleration (HRD) response, and also reduced subjective arousal ratings for highly arousing images, while increasing ratings for less arousing images. We conclude that REM TMR can facilitate a decrease in physiological and neurological responses to arousal. These findings have potential implications for the use of TMR in treatment of depression and anxiety disorders. HighlightsO_LITMR in REM sleep reduces Salience Network responses to emotional pictures. C_LIO_LITMR in REM sleep reduces heart rate deceleration to emotional pictures. C_LIO_LITMR in REM sleep reduces subjective arousal ratings of highly arousing images. C_LIO_LITMR in REM sleep provides a promising potential avenue for treatment of PTSD. C_LI

neuroscience↗

bioRxiv2023

A Spatiotemporal Compartmentalization of Glucose Metabolism Guides Mammalian Gastrulation Progression

Gastrulation is considered the sine qua non of embryogenesis, establishing a multidimensional structure and the spatial coordinates upon which all later developmental events transpire. At this time, the embryo adopts a heavy reliance on glucose metabolism to support rapidly accelerating changes in morphology, proliferation, and differentiation. However, it is currently unknown how this conserved metabolic shift maps onto the three-dimensional landscape of the growing embryo and whether it is spatially linked to the orchestrated cellular and molecular processes necessary for gastrulation. Here we identify that glucose is utilised during mouse gastrulation via distinct metabolic pathways to instruct local and global embryonic morphogenesis, in a cell type and stage-specific manner. Through detailed mechanistic studies and quantitative live imaging of mouse embryos, in parallel with tractable in vitro stem cell differentiation models and embryo-derived tissue explants, we discover that cell fate acquisition and the epithelial-to-mesenchymal transition (EMT) relies on the Hexosamine Biosynthetic Pathway (HBP) branch of glucose metabolism, while newly-formed mesoderm requires glycolysis for correct migration and lateral expansion. This regional and tissue-specific difference in glucose metabolism is coordinated with Fibroblast Growth Factor (FGF) activity, demonstrating that reciprocal crosstalk between metabolism and growth factor signalling is a prerequisite for gastrulation progression. We expect these studies to provide important insights into the function of metabolism in other developmental contexts and may help uncover mechanisms that underpin embryonic lethality, cancer, and congenital disease.

developmental biology↗

bioRxiv2023

Capturing Spatiotemporal Signaling Patterns in Cellular Data with Geometric Scattering Trajectory Homology

Neural signals are high-dimensional, noisy, and dynamic, making it challenging to extract interpretable features linked to behavior or disease. We introduce Neurospectrum, a framework that encodes neural activity as latent trajectories shaped by spatial and temporal structure. At each timepoint, signals are represented on a graph capturing spatial relationships, with a learnable attention mechanism highlighting important regions. These are embedded using graph wavelets and passed through a manifold-regularized autoencoder that preserves temporal geometry. The resulting latent trajectory is summarized using a principled set of descriptors - including curvature, path signatures, persistent homology, and recurrent networks -that capture multiscale geometric, topological, and dynamical features. These features drive downstream prediction in a modular, interpretable, and end-to-end trainable framework. We evaluate Neurospectrum on simulated and experimental datasets. It tracks phase synchronization in Kuramoto simulations, reconstructs visual stimuli from calcium imaging, and identifies biomarkers of obsessive-compulsive disorder in fMRI. Across tasks, Neurospectrum uncovers meaningful neural dynamics and outperforms traditional analysis methods.

bioinformatics↗

bioRxiv2022

Differential metabolic adaptations define responses of winner and loser oncogenic mutant stem cells in skin epidermis in vivo

Skin epithelial stem cells detect and correct aberrancies induced by oncogenic mutations. Different oncogenes invoke different mechanisms of epithelial tolerance: while wild-type cells outcompete {beta}-catenin-Gain-of-Function ({beta}catGOF) mutant cells, HrasG12V mutant cells outcompete wild-type cells1,2. Here we ask how metabolic states change as wild-type stem cells interface with mutant cells, and how this ultimately drives different cell competition outcomes. By adapting our live-imaging platform to track endogenous redox ratio (NAD(P)H/FAD) with single cell resolution in the same mice over time, we show that wild-type epidermal stem cells maintain robust redox ratio despite their heterogeneous cell cycle states. We discover that both {beta}catGOF and HrasG12V models lead to a rapid drop in redox ratios. However, the "winner" cells in each model (wild-type in {beta}catGOF and mutant in HrasG12V), rapidly recover their redox ratios, irrespective of the mutation induced. Using mass spectrometry (13C-LC-MS/MS)3, we find that both mutants increase flux through the oxidative tricarboxylic acid cycle, but the "winner" HrasG12V cells and the "loser" {beta}catGOF cells modulate glycolytic flux differently. Hence, we reveal the metabolic adaptations that define the hallmarks of winners and losers during cell competition in vivo and uncover the nodes of regulation unique to each cell fate.

cancer biology↗

bioRxiv2022

Mechanisms of vascular maturation and maintenance captured by longitudinal imaging of live mouse skin

A functional network of blood vessels is essential for organ growth and homeostasis. Yet, how the vasculature matures and maintains adult homeostasis remains elusive in live mice. By longitudinally tracking the same neonatal endothelial cells (ECs) over days to weeks, we found that capillary plexus expansion is driven by network-wide vessel regression and transient angiogenesis. A fixed number of neonatal ECs rearrange their positions to evenly distribute throughout the developing plexus and become positionally stable in adulthood. Upon injury, while neonatal ECs are predisposed to die, adult ECs survive through a plasmalemmal self-repair response. Furthermore, adult neighboring ECs reactivate migration to assist vessel repair. Lastly, neonatal vessel regression and adult vascular maintenance are orchestrated by temporally restricted VEGFR2 dependent signaling. Our work sheds light on fundamental cellular mechanisms that underlie both vascular maturation and adult homeostasis in vivo.

developmental biology↗

bioRxiv2022

Live imaging reveals chromatin compaction transitions and dynamic transcriptional bursting during stem cell differentiation in vivo

Stem cell differentiation requires dramatic changes in gene expression and global remodeling of chromatin architecture. How and when chromatin remodels relative to the transcriptional, behavioral, and morphological changes during differentiation remain unclear, particularly in an intact tissue context. Here, we develop a quantitative pipeline which leverages fluorescently-tagged histones and longitudinal imaging to track large-scale chromatin compaction changes within individual cells in a live mouse. Applying this pipeline to epidermal stem cells, we reveal that cell-to-cell chromatin compaction heterogeneity within the stem cell compartment emerges independent of cell cycle status, and instead is reflective of differentiation status. Chromatin compaction state gradually transitions over days as differentiating cells exit the stem cell compartment. Moreover, establishing live imaging of keratin-10 nascent RNA, which marks the onset of stem cell differentiation, we find that keratin-10 transcription is highly dynamic and largely precedes the global chromatin compaction changes associated with differentiation. Together, these analyses reveal that stem cell differentiation involves dynamic transcriptional states and gradual chromatin rearrangement.

genetics↗

bioRxiv2022

Oncogenic Kras induces spatiotemporally specific tissue deformation through converting pulsatile into sustained ERK activation

Tissue regeneration and maintenance rely on coordinated stem cell behaviors. This orchestration can be impaired by oncogenic mutations leading to tissue architecture disruption and ultimately cancer formation. However, it is still largely unclear how oncogenes perturb stem cells functions to break tissue architecture. Here, we used intravital imaging and a novel signaling reporter to investigate the mechanisms by which oncogenic Kras mutation causes tissue disruption in the hair follicle. Through longitudinally tracking the same hair follicles in live mice, we found that KrasG12D, a mutation that can lead to squamous cell carcinoma, induces epithelial tissue deformation in a spatiotemporally specific manner. This tissue architecture abnormality is linked with a spatial dysregulation of stem cell proliferation as well as abnormal migration during hair follicle growth. By using a reporter mouse that allows us to capture real-time ERK signal dynamics at the single cell level, we discovered that KrasG12D, but not a closely related mutation HrasG12V, converts the pulsatile ERK signal fluctuation in the stem cells into sustained activation. Furthermore, by combining drug treatment with longitudinal imaging, we demonstrated that temporary inhibiting ERK signal reverts the KrasG12D-induced tissue deformation, suggesting that sustained ERK activation leads to tissue architecture disruption in Kras mutant hair follicles. Altogether, our work suggests that oncogenic mutations induce tissue abnormalities when spatiotemporally specific conditions are met, which allows mutant stem cells to disturb local cell coordination through altering dynamic signal communications.

cancer biology↗

bioRxiv2022

Reorganizing Niche Architecture Still Preserves Organ Function in the Hair Follicle

Stem cells ability to build and replenish tissues depends on support from their niche. While niche architecture varies across different organs, the functional importance of niche architecture is unclear. During hair follicle growth, multipotent epithelial progenitors build hair via crosstalk with their remodeling fibroblast niche, the dermal papilla, providing a powerful model to functionally interrogate different niche architectures. Through intravital imaging, we show that dermal papilla fibroblasts remodel both individually and collectively to form a polarized, structurally robust niche. Polarized TGF{beta} signaling precedes structural niche polarity, and loss of TGF{beta} signaling in dermal papilla fibroblasts leads them to progressively lose their stereotypic architecture and instead surround the epithelium. The reorganized niche relocates multipotent progenitors, but nevertheless supports their proliferation and differentiation. However, progenitor differentiation is completed prematurely, resulting in compromised hair production. Overall, our results reveal that niche architecture optimizes organ efficiency, but is not absolutely essential for organ function.

developmental biology↗

bioRxiv2022

Wearing an Eye Mask During Overnight Sleep Improves Episodic Learning and Alertness

Ambient light can influence sleep structure and timing. We explored how wearing an eye-mask to block light during overnight sleep impacts on memory and alertness, changes that could benefit everyday tasks like studying or driving. In Experiment 1, ninety-four 18-35-year-olds wore an eye-mask while they slept every night for a week and underwent a control condition in which light was not blocked for another week. Five habituation nights were followed by a cognitive battery on the sixth and seventh days. This revealed superior episodic encoding and an improvement on alertness when using the mask. In Experiment 2, thirty-five 18-35-year-olds used a wearable device to monitor sleep with and without the mask. This replicated the encoding benefit and showed that it was predicted by time spent in slow wave sleep. Our findings suggest that wearing an eye-mask during overnight sleep can improve episodic encoding and alertness the next day. Statement of relevanceSleep is crucial for alertness and for preparing the human brain to encode new information. However, it can be disrupted by external stimuli such as light or sounds. This study explored wearing an eye mask as a potential cognitive enhancer which protects overnight sleep by blocking ambient light. We found that wearing a mask increased alertness and facilitated the encoding of novel information the next day. Furthermore, the benefit to memory was predicted by time spent in slow wave sleep while wearing the mask. This suggests wearing an eye mask during sleep is an effective, economical, and non-invasive behaviour that could benefit cognitive function and lead to measurable impacts on every-day life.

neuroscience↗

bioRxiv2022

Injury suppresses Ras cell competitive advantage through enhanced wild-type cell proliferation

Healthy skin is a tapestry of wild-type and mutant clones. Although injury can cooperate with Ras mutations to promote tumorigenesis, the consequences in genetically mosaic skin are unknown. Here, we show that wild-type cells prevent oncogenic Ras-induced aberrant growth after injury. Although HrasG12V/+ and KrasG12D/+ cells outcompete wild-type cells in uninjured, mosaic tissue, their competitive advantage is suppressed after injury due to a selective increase in wild-type cell proliferation. EGFR inhibition abolishes the competitive advantage of wild-type cells after injury of HrasG12V/+-mosaic skin. Global loss of the cell cycle inhibitor p21 increases wild-type cell proliferation even without injury, suppressing the competitive advantage of HrasG12V/+ cells. Thus, injury plays an unanticipated role in switching the competitive balance between oncogenic and wild-type cells in genetically mosaic skin. One sentence SummaryInjury-repair selectively induces wild-type cell proliferation to suppress oncogenic growth in Ras-mosaic skin epithelium.

cell biology↗

bioRxiv2021

Tissue-wide coordination of calcium signaling regulates the epithelial stem cell pool during homeostasis

Skin epidermal homeostasis is maintained via constant regeneration by stem cells, which must communicate to balance their self-renewal and differentiation. A key molecular pathway, Ca2+ signaling has been implicated as a signal integrator in developing and wounded epithelial tissues[1, 2, 3, 4]. Yet how stem cells carry out this signaling across a regenerative tissue remains unknown due to significant challenges in studying signaling dynamics in live mice, limiting our understanding of the mechanisms of stem cell communication during homeostasis. To interpret high dimensional signals that have complex spatial and temporal patterns, we combined optimized imaging of Ca2+ signaling in thousands of epidermal stem cells in living mice with a new machine learning tool, Geometric Scattering Trajectory Homology (GSTH). Using a combination of signal processing, data geometry, and topology, GSTH captures patterns of signaling at multiple scales, either between direct or distant stem cell neighbors. Here we show that epidermal stem cells display dynamic intercellular Ca2+ signaling among neighborhoods of up to 10 cells that is surprisingly coordinated and directed through time across a pool of thousands of stem cells. We find that this collective coordination is an emergent property of the stem cell compartment, distinct from excitatory quiescent neuronal tissues. We demonstrate that cycling stem cells, specifically G2 cells, govern homeostatic patterns of Ca2+ signaling. Stem cells in different cell cycle stages dynamically regulate localization of the gap junction component Connexin43 (Cx43). Lastly, we uncouple global from local communication and identify Cx43 as the molecular mediator necessary for connectivity between local signaling neighborhoods. This work provides resolution in how stem cells at different stages of the cell cycle communicate and how that diversity of phases is essential for tissue wide communication and signaling flow during epidermal regeneration. Our approach provides a framework to investigate stem cell populations and their signaling dynamics, previously not possible.

cell biology↗

bioRxiv2021

Graph-based machine learning reveals rules of spatiotemporal cell interactions in tissues

Robustness in developing and homeostatic tissues is supported by various types of spatiotemporal cell-to-cell interactions. Although live imaging and cell tracking are powerful in providing direct evidence of cell coordination rules, extracting and comparing these rules across many tissues with potentially different length and timescales of coordination requires a versatile framework of analysis. Here we demonstrate that graph neural network (GNN) models are suited for this purpose, by showing how they can be applied to predict cell fate in tissues and utilized to infer the cell interactions governing the multicellular dynamics. Analyzing the live mammalian epidermis data, where spatiotemporal graphs constructed from cell tracks and cell contacts are given as inputs, GNN discovers distinct neighbor cell fate coordination rules that depend on the region of the body. This approach demonstrates how the GNN framework is powerful in inferring general cell interaction rules from live data without prior knowledge of the signaling involved.

cell biology↗

bioRxiv2021

Skin-resident immune cells actively coordinate their distribution with epidermal cells during homeostasis

Our organs consist of multiple cell types that ensure proper architecture and function. How different cell types coexist and interact to maintain their homeostasis in vivo remain elusive. The skin epidermis comprises mostly epithelial cells, but also harbors Langerhans cells (LCs) and Dendritic Epidermal T cells (DETCs). In response to injury or infection, LCs and DETCs become activated and play critical immunological roles. During homeostasis, they coexist with epithelial cells in the basal layer of the epidermis. Whether, and how, distributions of LCs and DETCs are regulated during homeostasis is unclear. Here, we addressed this question by tracking LCs, DETCs and epithelial basal cells over time within the skin of live adult mice. We show that LCs and DETCs maintain their overall position despite continuous turnover of neighboring basal epithelial stem cells. Moreover, LCs and DETCs rapidly and maximally explore basal epithelial cell junctions through their dendritic extensions. Altering the epithelial cell density triggers corresponding changes in the immune cell density, but not vice versa, suggesting that epithelial cells determine immune tissue composition in the epidermis. Moreover, LCs and DETCs are organized in a tiling pattern that is actively maintained. When LCs or DETCs are ectopically removed, neighboring epidermal LCs or DETCs, respectively, move into the emptied spaces and re-establish the tiling pattern. Finally, LCs require the GTPase Rac1 to maintain their positional stability, density and tiling pattern. Overall, we discovered that epidermal cells regulate the density of immune cells during homeostasis, and that immune cells actively maintain a non-random spatial distribution, reminiscent of neuronal self-avoidance. We propose that these cellular mechanisms provide the epidermis with an optimal response to environmental insults.

cell biology↗

bioRxiv2021

Gradual differentiation uncoupled from cell cycle exit generates heterogeneity in the epidermal stem cell layer.

High turnover tissues continually lose specialized cells that are replaced by stem cell activity. In the adult mammalian epidermis, it is unclear how molecularly heterogenous stem/progenitor cell populations fit into the complete trajectory of epidermal differentiation. We show that differentiation, from commitment to exit from the stem cell layer, is a multi-day process wherein cells transit through a continuum of transcriptional changes. Differentiation-committed cells remain capable of dividing to produce daughter cells fated to further differentiate, demonstrating that differentiation is uncoupled from cell cycle exit. These cell divisions are not required as part of an obligate transit amplifying program but instead protect density in the stem cell layer. Thus, instead of distinct contributions from multiple progenitors, a continuous gradual differentiation process fuels homeostatic epidermal turnover. One sentence summaryHeterogeneity in the epidermal stem cell layer reflects a gradual differentiation program that is uncoupled from the loss of proliferative capacity.

cell biology↗

bioRxiv2019

3D super-resolution deep-tissue imaging in living mice

Stimulated emission depletion (STED) microscopy enables the three-dimensional (3D) visualization of dynamic nanoscale structures in living cells, offering unique insights into their organization. However, 3D-STED imaging deep inside biological tissue is obstructed by optical aberrations and light scattering. We present a STED system that overcomes these challenges. Through the combination of 2-photon excitation, adaptive optics, far-red emitting organic dyes, and a long-working distance water-immersion objective lens, our system achieves aberration-corrected 3D super-resolution imaging, which we demonstrate 164 {micro}m deep in fixed mouse brain tissue and 76 {micro}m deep in the brain of a living mouse.

biophysics↗