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Heart failure is the final common stage of most cardiopathies. Cardiomyocytes (CM) connect with others via their extremities by intercalated disk protein complexes. This planar and directional organization of myocytes is crucial for mechanical coupling and anisotropic conduction of the electric signal in the heart. One of the hallmarks of heart failure is alterations in the contact sites between CM. Yet no factor on its own is known to coordinate CM polarized organization. We have previously shown that PDZRN3, an ubiquitine ligase E3 expressed in various tissues including the heart, mediates a branch of the Planar cell polarity (PCP) signaling involved in tissue patterning, instructing cell polarity and cell polar organization within a tissue. PDZRN3 is expressed in the embryonic mouse heart then its expression dropped significantly postnatally corresponding with heart maturation and CM polarized elongation. A moderate CM overexpression of Pdzrn3 ( Pdzrn3 OE) during the first week of life, induced a severe eccentric hypertrophic phenotype with heart failure. In models of pressure-overload stress heart failure, CM-specific  Pdzrn3 knockout showed complete protection against degradation of heart function. We reported that Pdzrn3 signaling induced PKC ζ expression, c-Jun nuclear translocation and a reduced nuclear ß catenin level, consistent markers of the planar non-canonical Wnt signaling in CM. We then show that subcellular localization (intercalated disk) of junction proteins as Cx43, ZO1 and Desmoglein 2 was altered in Pdzrn3 OE mice, which provides a molecular explanation for impaired CM polarization in these mice. Our results reveal a novel signaling pathway that controls a genetic program essential for heart maturation and maintenance of overall geometry, as well as the contractile function of CM, and implicates PDZRN3 as a potential therapeutic target for the prevention of human heart failure.

Quantitative analysis of the vascular network anatomy is critical for the understanding of the vasculature structure and function. In this study, we have combined microcomputed tomography (microCT) and computational analysis to provide quantitative three-dimensional geometrical and topological characterization of the normal kidney vasculature, and to investigate how 2 core genes of the Wnt/planar cell polarity, Frizzled4 and Frizzled6, affect vascular network morphogenesis. Experiments were performed on frizzled4 (Fzd4-/-) and frizzled6 (Fzd6-/-) deleted mice and littermate controls (WT) perfused with a contrast medium after euthanasia and exsanguination. The kidneys were scanned with a high-resolution (16 μm) microCT imaging system, followed by 3D reconstruction of the arterial vasculature. Computational treatment includes decomposition of 3D networks based on Diameter-Defined Strahler Order (DDSO). We have calculated quantitative (i) Global scale parameters, such as the volume of the vasculature and its fractal dimension (ii) Structural parameters depending on the DDSO hierarchical levels such as hierarchical ordering, diameter, length and branching angles of the vessel segments, and (iii) Functional parameters such as estimated resistance to blood flow alongside the vascular tree and average density of terminal arterioles. In normal kidneys, fractal dimension was 2.07±0.11 (n = 7), and was significantly lower in Fzd4-/- (1.71±0.04; n = 4), and Fzd6-/- (1.54±0.09; n = 3) kidneys. The DDSO number was 5 in WT and Fzd4-/-, and only 4 in Fzd6-/-. Scaling characteristics such as diameter and length of vessel segments were altered in mutants, whereas bifurcation angles were not different from WT. Fzd4 and Fzd6 deletion increased vessel resistance, calculated using the Hagen-Poiseuille equation, for each DDSO, and decreased the density and the homogeneity of the distal vessel segments. Our results show that our methodology is suitable for 3D quantitative characterization of vascular networks, and that Fzd4 and Fzd6 genes have a deep patterning effect on arterial vessel morphogenesis that may determine its functional efficiency.

Cerebral small vessel disease (cSVD) is a leading cause of stroke, cognitive decline and dementia, for which no specific mechanism-based treatments are currently available. Previous genomic studies identified associations of common variants at chr17q25 with cSVD features, with converging evidence for a causal involvement of TRIM47 , an ubiquitin ligase enriched in brain endothelial cells (ECs). In the present study, we devised a multilayered experimental plan to decipher the biological mechanisms underlying TRIM47’s role in cSVD pathophysiology. Trim47 -deficient mice, which model the human genetic anomaly, exhibit major cognitive impairments, increased blood-brain barrier (BBB) permeability, and astrogliosis, without neuroinflammation. Inducible deletion of Trim47 in ECs recapitulates these phenotypes highlighting the contribution of endothelial TRIM47 in maintaining brain homeostasis. In vitro and in vivo data, demonstrate that TRIM47 regulates the resilience of brain ECs to oxidative stress by binding to KEAP1, stabilizing NRF2 protein levels and promoting the NRF2 pathway. Treatment with the NRF2 activator tert-butylhydroquinone prevented BBB and cognitive impairment in Trim47 -mutant mice. By leveraging unique human proteomic data, we propose that modulation of the TRIM47/NRF2 pathway could predict an increased susceptibility to cSVD, suggesting that targeting this pathway may offer a promising therapeutic approach for vascular cognitive impairment and dementia. Functional analysis of TRIM47 uncovers its role in regulating endothelial oxidative stress responses and Blood-Brain-Barrier stability in the mouse, linking KEAP1/NRF2 pathway dysregulation to cognitive decline in vascular dementia.

Hypertension remains the leading cause of cerebral, cardiac, renal, and retinal vascular damage. However, genetic determinants underlying organ-specific vulnerability are poorly understood, and commonly used mouse models, notably C57BL/6J, often fail to recapitulate severe hypertensive complications seen in humans. This study compares the widely used C57BL/6J mouse strain with the genetically distinct 129S1/SvlmJ strain under hypertensive stress, aiming to identify a model that better reproduces hypertensive target organ damage. Moderate hypertension was induced in 129S1/SvlmJ and C57BL/6J mice using chronic infusion of angiotensin II (600 ng/kg/min). Despite comparable blood pressure elevations, only 129S1/SvlmJ mice developed severe organ damage, including cognitive impairment, pronounced blood-brain barrier disruption, retinal vasculopathy, cardiac hypertrophy, and podocyte lesions with albuminuria. In contrast, C57BL/6J mice exhibited markedly less organ injury under the experimental conditions tested. Transcriptomic analysis of cerebral microvessels identified distinct inflammatory and immune-related signatures between strains, paralleling their vascular phenotypes. These immune profiles appear as hallmarks of strain-specific susceptibility rather than as direct protective or deleterious mechanisms. This study demonstrates that genetic background critically shapes hypertensive complications, identifying the 129S1/SvlmJ strain as a relevant and translational model of hypertensive target organ damage. Beyond reproducing key features of severe hypertension, this model provides a framework to investigate the pathways linking genetic susceptibility, vascular injury, and end-organ damage.

Development and stabilization of a vascular plexus requires the coordination of multiple signalling processes. Wnt planar cell polarity (PCP) signalling is critical in vertebrates for diverse morphogenesis events, which coordinate cell orientation within a tissue-specific plane. However, its functional role in vascular morphogenesis is not well understood. Here we identify PDZRN3, an ubiquitin ligase, and report that Pdzrn3 deficiency impairs embryonic angiogenic remodelling and postnatal retinal vascular patterning, with a loss of two-dimensional polarized orientation of the intermediate retinal plexus. Using in vitro and ex vivo Pdzrn3 loss-of-function and gain-of-function experiments, we demonstrate a key role of PDZRN3 in endothelial cell directional and coordinated extension. PDZRN3 ubiquitinates Dishevelled 3 (Dvl3), to promote endocytosis of the Frizzled/Dvl3 complex, for PCP signal transduction. These results highlight the role of PDZRN3 to direct Wnt PCP signalling, and broadly implicate this pathway in the planar orientation and highly branched organization of vascular plexuses. Wnt/planar cell polarity (PCP) signalling regulates angiogenesis in vertebrates. Here the authors show that the E3 ubiquitin ligase PDZRN3 ubiquitinates the PCP-signalling protein Dishevelled 3 to promote Wnt/PCP signalling, directing embryonic and postnatal remodelling of the vasculature in mouse.

Mesenchymal stem cells (MSC) are multipotent postnatal stem cells, involved in the treatment of ischemic vascular diseases. We investigate the ability of MSC, exposed to short-term hypoxic conditions, to participate in vascular and tissue regeneration in an in vivo model of hindlimb ischemia. Transplantation of hypoxic preconditioned murine MSC (HypMSC) enhanced skeletal muscle regeneration at day 7, improved blood flow and vascular formation compared to injected nonpreconditioned MSC (NormMSC). These observed effects were correlated with an increase in HypMSC engraftment and a putative role in necrotic skeletal muscle fiber clearance. Moreover, HypMSC transplantation resulted in a large increase in Wnt4 (wingless-related MMTV integration site 4) expression and we demonstrate its functional significance on MSC proliferation and migration, endothelial cell (EC) migration, as well as myoblast differentiation. Furthermore, suppression of Wnt4 expression in HypMSC, abrogated the hypoxia-induced vascular regenerative properties of these cells in the mouse hindlimb ischemia model. Our data suggest that hypoxic preconditioning plays a critical role in the functional capabilities of MSC, shifting MSC location in situ to enhance ischemic tissue recovery, facilitating vascular cell mobilization, and skeletal muscle fiber regeneration via a paracrine Wnt-dependent mechanism.

Abstract Heart failure is the final common stage of most cardiopathies. Cardiomyocytes (CM) connect with others via their extremities by intercalated disk protein complexes. This planar and directional organization of myocytes is crucial for mechanical coupling and anisotropic conduction of the electric signal in the heart. One of the hallmarks of heart failure is alterations in the contact sites between CM. Yet no factor on its own is known to coordinate CM polarized organization. We have previously shown that PDZRN3, an ubiquitine ligase E3 expressed in various tissues including the heart, mediates a branch of the Planar cell polarity (PCP) signaling involved in tissue patterning, instructing cell polarity and cell polar organization within a tissue. PDZRN3 is expressed in the embryonic mouse heart then its expression dropped significantly postnatally corresponding with heart maturation and CM polarized elongation. A moderate CM overexpression of Pdzrn3 ( Pdzrn3 OE) during the first week of life, induced a severe eccentric hypertrophic phenotype with heart failure. In models of pressure-overload stress heart failure, CM-specific Pdzrn3 knockout showed complete protection against degradation of heart function. We reported that Pdzrn3 signaling induced PKC ζ expression, c-Jun nuclear translocation and a reduced nuclear ß catenin level, consistent markers of the planar non-canonical Wnt signaling in CM. We then show that subcellular localization (intercalated disk) of junction proteins as Cx43, ZO1 and Desmoglein 2 was altered in Pdzrn3 OE mice, which provides a molecular explanation for impaired CM polarization in these mice. Our results reveal a novel signaling pathway that controls a genetic program essential for heart maturation and maintenance of overall geometry, as well as the contractile function of CM, and implicates PDZRN3 as a potential therapeutic target for the prevention of human heart failure.

Mesenchymal stem cells (MSC) are multipotent postnatal stem cells, involved in the treatment of ischemic vascular diseases. We investigate the ability of MSC, exposed to short-term hypoxic conditions, to participate in vascular and tissue regeneration in an in vivo model of hindlimb ischemia. Transplantation of hypoxic preconditioned murine MSC (HypMSC) enhanced skeletal muscle regeneration at day 7, improved blood flow and vascular formation compared to injected nonpreconditioned MSC (NormMSC). These observed effects were correlated with an increase in HypMSC engraftment and a putative role in necrotic skeletal muscle fiber clearance. Moreover, HypMSC transplantation resulted in a large increase in Wnt4 (wingless-related MMTV integration site 4) expression and we demonstrate its functional significance on MSC proliferation and migration, endothelial cell (EC) migration, as well as myoblast differentiation. Furthermore, suppression of Wnt4 expression in HypMSC, abrogated the hypoxia-induced vascular regenerative properties of these cells in the mouse hindlimb ischemia model. Our data suggest that hypoxic preconditioning plays a critical role in the functional capabilities of MSC, shifting MSC location in situ to enhance ischemic tissue recovery, facilitating vascular cell mobilization, and skeletal muscle fiber regeneration via a paracrine Wnt-dependent mechanism.

Heart failure is the final common stage of most cardiopathies. Cardiomyocytes connect with others via their extremities by intercalated disk protein complexes. This planar and directional organization of myocytes is crucial for mechanical coupling and anisotropic conduction of the electric signal in the heart. One of the hallmarks of heart failure is alterations in the contact sites between cardiomyocytes. Yet no factor on its own is known to coordinate cardiomyocyte polarized organization. We report enhanced levels of an ubiquitine ligase Pdzrn3 in diseased hypertrophic human and mouse myocardium, which correlates with a loss of cardiomyocyte polarized elongation. We provide evidence that Pdzrn3 has a causative role in heart failure. We found that cardiac Pdzrn3 deficiency protected against heart failure while over expression of Pdzrn3 in mouse cardiomyocytes during the first weeks of life, impaired postnatal cardiomyocyte maturation leading to premature death. Our results reveal a novel signaling pathway that controls a genetic program essential for heart maturation and maintenance of overall geometry, as well as the contractile function of cardiomyocytes, and implicates PDZRN3 as a potential therapeutic target for the prevention of human heart failure. Competing Interest Statement The authors have declared no competing interest.

Cerebral small vessel disease (cSVD) is a leading cause of stroke, cognitive decline and dementia, for which no specific mechanism-based treatments are available to date. Genome-wide and whole-exome association studies previously identified robust associations of common variants at chr17q25 with cSVD features on magnetic resonance imaging, with converging bioinformatic and experimental data for a causal involvement of TRIM47. Preliminary functional evaluation of TRIM47, an ubiquitin ligase enriched in brain endothelial cells (ECs), suggested its potential role in blood brain barrier (BBB) integrity. Here, we show that TRIM47 regulates brain EC resilience and adaptive responses to oxidative stress by binding to KEAP1, stabilizing NRF2 protein levels and promoting the NRF2 antioxidant signaling pathway. In vivo, Trim47-deficient mice exhibit downregulation of NRF2 target genes, BBB dysfunction, astrogliosis and cognitive impairments. Endothelial-specific deletion of Trim47 recapitulates these phenotypes. Treatment with the NRF2 activator tert- butylhydroquinone normalized BBB integrity and cognitive function in Trim47-deficient mice, highlighting the role of endothelial TRIM47 in driving brain homeostasis through NRF2 pathway activation. This work indicates that loss of the protective TRIM47/NRF2 axis may increase the susceptibility to developing human cSVD and that targeting the TRIM47/NRF2 axis could be a promising therapeutic approach for vascular cognitive impairment and dementia.