Biology subjects

Luttun, A.

Publications and source records attributed to Luttun, A..

4 recordsLinked to original sources

bioRxiv2026

Matrix stiffness shifts the endothelial shear stress set point for angiogenic activation

AimsEndothelial cells (ECs) are simultaneously exposed to wall shear stress (SS) from blood flow and substrate stiffness (SFN) from the extracellular matrix, yet how these cues are integrated to shape endothelial behavior remains incompletely understood. We applied an unbiased transcriptomics strategy to define how SS and substrate SFN jointly encode endothelial state transitions and determine angiogenic activation thresholds. Methods and ResultsWe generated a factorial RNA-Seq dataset of human ECs exposed to 14 combinations of SS (0-40 dynes/cm{superscript 2}) and SFN (1-100 kPa). DESeq2 with likelihood ratio testing identified genes whose expression was significantly associated with SS, SFN, or their interaction. SS was the dominant driver of global transcriptional variation and elicited non-linear transcriptional responses, whereas substrate SFN had a smaller direct effect but significantly modulated the endothelial response to flow. Interaction analyses identified gene programs associated with vascular remodeling, including angiogenesis and migration. Pathway-level analyses revealed that substrate SFN shifts the SS threshold at which angiogenic transcriptional programs become activated, indicating that SFN tunes the endothelial angiogenic set point rather than scaling the response magnitude. Moreover, activated states differed qualitatively across mechanical contexts, reflecting context-dependent reweighting of shared inflammatory, stress, and adaptive/remodeling programs. Finally, siRNA-mediated YAP1 knockdown confirmed its contribution to SS-SFN-dependent gene regulation. ConclusionThis study provides a systems-level experimental and bioinformatic framework for disentangling multifactorial mechanotransduction in ECs. Although SS predominates in shaping endothelial transcriptomes, substrate SFN critically modulates how ECs interpret flow by shifting the threshold for angiogenic transcriptional activation and reweighting downstream pathways. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/740002v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@b615d7org.highwire.dtl.DTLVardef@54121dorg.highwire.dtl.DTLVardef@1715e4corg.highwire.dtl.DTLVardef@1e6018e_HPS_FORMAT_FIGEXP M_FIG C_FIG Translational PerspectiveBy systematically combining substrate stiffness and shear stress across physiological and pathological ranges, we provide a reference dataset for vascular mechanobiology. These data enable interpretation of endothelial responses across clinically relevant mechanical environments, including stiffness ranges in different organs (1- brain; 10-muscle or fibrotic liver; 100-aortic valves; kPa), shear stress ranges in different vascular beds (5-veins, 25-capillaries, 40-valves; dynes/cm2), and disease-associated changes such as matrix stiffening. Incorporating interactions between mechanical cues may improve the design of in vitro vascular models and enhance computational prediction of vascular remodeling.

cell biology↗

bioRxiv2024

Atheroprone Flow Activates SMAD-FOXO1 to drive Endothelial-to-Mesenchymal Transition and Atherosclerosis

BackgroundCardiovascular diseases are the leading cause of death worldwide with atherosclerosis as the main underlying pathology. A hallmark of atherosclerotic lesion formation is endothelial-to-mesenchymal transition (EndoMT) triggered by perturbed blood flow patterns at arterial bifurcations and curvatures. SMAD transcription factors (TFs), activated by bone morphogenetic protein (BMP) 9/10 or transforming growth factor beta (TGF{beta}) signaling, are indispensable for endothelial homeostasis. Yet, they also play a significant role in stimulating EndoMT. How different interacting co-factors mediate the shift towards a pathological SMAD response remains elusive. MethodsWe generated endothelial cell (EC)-specific SMAD1/5 or SMAD2/3 knock-out mice and performed assay for transposase accessible chromatin sequencing (ATAC-Seq) of EC nuclei from regions of atheroprone (aortic arch) and atheroprotective (descending thoracic aorta) flow to identify transcriptional co-regulators of SMADs. We validated this using single-cell (sc)ATAC-Seq and immunofluorescence staining data from wild-type mice. To assess conservation of our findings for the human situation, we performed co-immunoprecipitation and proximity ligation assays in human aortic ECs (HAoECs). We exposed HAoECs to pathological or physiological (i.e. oscillatory or pulsatile) flow and performed ATAC- and RNA-Seq. Next, transcriptomic and chromatin accessibility data were integrated and motif enrichment and TF footprinting analysis were performed. Finally, we used siRNA-mediated approaches, TF inhibition, and luciferase-based reporter gene assays to analyze the transcriptional response of target TFs and explored their presence in plaques of atheroprone low-density lipoprotein receptor-deficient mice. ResultsWe observed enrichment of FOXO TF family motifs in DNA loci with increased accessibility in response to atheroprone flow in vitro and in vivo. These motifs were associated with genes displaying enhanced mRNA expression. We observed that FOXO motifs are enriched in peaks lost upon EC-specific SMAD KO in mice. We identified SMADs and FOXO1 as interacting partners that form complexes upon atheroprone flow stimulation. Inhibitor experiments revealed that FOXO1 and SMADs mediate EndoMT upon atheroprone flow exposure by upregulating SNAI2. ConclusionWe identified SMAD/FOXO1 complexes that mediate EndoMT in response to atheroprone flow. Targeting this interaction can potentially reduce atherosclerotic burden by interfering with pathological flow-induced EndoMT and thus disease progression.

genomics↗

bioRxiv2021

Prdm16 and Notch functionally and physically interact during artery development

Proper arterial versus venous endothelial lineage identity is required to establish a hierarchical network of arteries and veins and prevent the occurrence of life-threatening arteriovenous malformations. The molecular mechanisms that govern arteriovenous lineage specification remain however incompletely understood. Here, we demonstrate that the transcription factor Prdm16 is expressed in arterial but not venous endothelial cells (ECs) from the earliest stages of development, where it actively promotes arterial EC identity by enhancing canonical Notch activity, while simultaneously suppressing the alternative venous cell fate. Concordantly, our results in zebrafish show that Prdm16 coordinates proper arterial development and arteriovenous lineage specification together with canonical Notch signaling, as combined loss of prdm16 and notch in zebrafish invariably leads to arteriovenous malformations (AVMs). Although the arterializing effect of Prdm16 in human ECs is dependent on the absolute levels of the cleaved intracellular domain of the Notch receptors (NICD), Prdm16 does not increase NICD levels per se. Rather, Prdm16 physically and functionally interacts with NICD to potentiate its effect. Prdm16 further finetunes Notch signaling and arterial development by complexing with the Notch downstream effector Hey2, which regulates arterial lineage specification and development across species. Together, our data demonstrate that Prdm16 act as a rheostat for endothelial Notch activity and suggest that Prdm16 signaling may constitute a novel therapeutic target for AVMs.

developmental biology↗

bioRxiv2019

Autologous micrograft accelerates endogenous wound healing response via ERK-induced cell migration

Defective fibroblast migration causes delayed wound healing (WH) and chronic skin lesions. Autologous micrograft (AMG) therapies have recently emerged as a new effective treatment able to improve wound healing capacity. However, the molecular mechanisms connecting their beneficial outcomes with the wound healing process are still unrevealed. Here, we show that AMG modulates primary fibroblast migration and accelerates skin re-epithelialization without affecting cell proliferation. We demonstrate that AMG is enriched in a pool of WH-associated growth factors that may provide the initiation signal for a faster endogenous wound healing response. This, in turn leads to increased cell migration rate by elevating activity of extracellular signal-regulated kinase (ERK) pathway and subsequent activation of matrix metalloproteinase expression and their extracellular enzymatic activity. Moreover, AMG-treated wounds showed increased granulation tissue formation and organized collagen content. Overall, we shed light on AMG molecular mechanism supporting its potential to trigger a highly improved wound healing process.

molecular biology↗