Search

Elastin, the main component of elastic fibers, is synthesized only in early life and provides the blood vessels with their elastic properties. With aging, elastin is progressively degraded, leading to arterial enlargement, stiffening, and dysfunction. Also, elastin is a key regulator of vascular smooth muscle cell proliferation and migration during development since heterozygous mutations in its gene (Eln) are responsible for a severe obstructive vascular disease, supravalvular aortic stenosis, isolated or associated to Williams syndrome. Here, we have studied whether early elastin synthesis could also influence the aging processes, by comparing the structure and function of ascending aorta from 6- and 24-month-old Eln+/- and Eln+/+ mice. Eln+/- animals have high blood pressure and arteries with smaller diameters and more rigid walls containing additional although thinner elastic lamellas. Nevertheless, longevity of these animals is unaffected. In young adult Eln+/- mice, some features resemble vascular aging of wild-type animals: cardiac hypertrophy, loss of elasticity of the arterial wall through enhanced fragmentation of the elastic fibers, and extracellular matrix accumulation in the aortic wall, in particular in the intima. In Eln+/- animals, we also observed an age-dependent alteration of endothelial vasorelaxant function. On the contrary, Eln+/- mice were protected from several classical consequences of aging visible in aged Eln+/+ mice, such as arterial wall thickening and alteration of alpha(1)-adrenoceptor-mediated vasoconstriction. Our results suggest that early elastin expression and organization modify arterial aging through their impact on both vascular cell physiology and structure and mechanics of blood vessels. [ABSTRACT FROM AUTHOR]

Force-driven cellular interactions are crucial for cancer cell invasion but remain underexplored in vascular abnormalities. Cerebral cavernous malformations (CCM), a vascular abnormality characterized by leaky vessels, involves CCM mutant cells recruiting wild-type endothelial cells to form and expand mosaic lesions. The mechanisms behind this recruitment remain poorly understood. Here, we use an in-vitro model of angiogenic invasion with traction force microscopy to reveal that hyper-angiogenic Ccm2-silenced endothelial cells enhance angiogenic invasion of neighboring wild-type cells through force and extracellular matrix-guided mechanisms. We demonstrate that mechanically hyperactive CCM2-silenced tips guide wild-type cells by transmitting pulling forces and by creating paths in the matrix, in a ROCKs-dependent manner. This is associated with reinforcement of β1 integrin and actin cytoskeleton in wild-type cells. Further, wild-type cells are reprogrammed into stalk cells and activate matrisome and DNA replication programs, thereby initiating proliferation. Our findings reveal how CCM2 mutants hijack wild-type cell functions to fuel lesion growth, providing insight into the etiology of vascular malformations. By integrating biophysical and molecular techniques, we offer tools for studying cell mechanics in tissue heterogeneity and disease progression., (© 2024. The Author(s).)

Despite initial high response rates to first-line EGFR TKI, all non-small-cell lung cancer (NSCLC) with EGFR-activating mutation will ultimately develop resistance to treatment. Identification of resistance mechanisms is critical to adapt treatment and improve patient outcomes. Here, we show that a PPP3CB transcript that encodes full-length catalytic subunit 2B of calcineurin accumulates in EGFR-mutant NSCLC cells with acquired resistance against different EGFR TKIs and in post-progression biopsies of NSCLC patients treated with EGFR TKIs. Neutralization of PPP3CB by siRNA or inactivation of calcineurin by cyclosporin A induces apoptosis in resistant cells treated with EGFR TKIs. Mechanistically, EGFR TKIs increase the cytosolic level of calcium and trigger activation of a calcineurin/MEK/ERK pathway that prevents apoptosis. Combining EGFR, calcineurin, and MEK inhibitors overcomes resistance to EGFR TKI in both in vitro and in vivo models. Our results identify PPP3CB overexpression as a new mechanism of acquired resistance to EGFR TKIs, and provide a promising therapeutic approach for NSCLC patients that progress under TKI treatment., (© 2024 Gazzeri et al.)

Confining light illumination in the three dimensions of space is a challenge for various applications. Among these, optogenetic methods developed for live experiments in cell biology would benefit from such a localized illumination as it would improve the spatial resolution of diffusive photosensitive proteins leading to spatially constrained biological responses in specific subcellular organelles. Here, we describe a method to create and move a focused evanescent spot, at the interface between a glass substrate and an aqueous sample, across the field of view of a high numerical aperture microscope objective, using a digital micro-mirror device (DMD). We show that, after correcting the optical aberrations, light is confined within a spot of sub-micron lateral size and ∼100 nm axial depth above the coverslip, resulting in a volume of illumination drastically smaller than the one generated by a standard propagative focus. This evanescent focus is sufficient to induce a more intense and localized recruitment compared to a propagative focus on the optogenetic system CRY2-CIBN, improving the resolution of its pattern of activation.

Dendritic cell (DC) subsets play a crucial role in shaping anti-tumour immunity. Cancer escapes from the control immune system by hijacking DC functions. Yet, bases for such subversion are only partially understood. Tumour cells display aberrant glycan motifs on surface glycoproteins and glycolipids. Such carbohydrate patterns can be sensed by DCs through C-type lectin receptors (CLRs) that are critical to shape and orientate immune responses. We recently demonstrated that melanoma tumour cells harboured an aberrant 'glyco-code,' and that circulating and tumour-infiltrating DCs from melanoma patients displayed major perturbations in their CLR profiles. To decipher whether melanoma, through aberrant glycan patterns, may exploit CLR pathways to mislead DCs and evade immune control, we explored the impact of glycan motifs aberrantly found in melanoma (neoglycoproteins [NeoGP] functionalised with Gal, Man, GalNAc, s-Tn, fucose [Fuc] and GlcNAc residues) on features of human DC subsets (cDC2s, cDC1s and pDCs). We examined the ability of glycans to bind to purified DCs, and assessed their impact on DC basal properties and functional features using flow cytometry, confocal microscopy and multiplex secreted protein analysis. DC subsets differentially bound and internalised NeoGP depending on the nature of the glycan. Strikingly, Fuc directly remodelled the expression of activation markers and immune checkpoints, as well as the cytokine/chemokine secretion profile of DC subsets. NeoGP interfered with Toll like receptor (TLR)-signalling and pre-conditioned DCs to exhibit an altered response to subsequent TLR stimulation, dampening antitumor mediators while triggering pro-tumoral factors. We further demonstrated that DC subsets can bind NeoGP through CLRs, and identified GalNAc/MGL and s-Tn/ C-type lectin-like receptor 2 (CLEC2) as potential candidates. Moreover, DC dysfunction induced by tumour-associated carbohydrate molecules may be reversed by interfering with the glycan/CLR axis. These findings revealed the glycan/CLR axis as a promising checkpoint to exploit in order to reshape potent antitumor immunity while impeding immunosuppressive pathways triggered by aberrant tumour glycosylation patterns. This may rescue DCs from tumour hijacking and improve clinical success in cancer patients., (© 2023 John Wiley & Sons Ltd.)

HIV-1 budding as well as many other cellular processes require the Endosomal Sorting Complex Required for Transport (ESCRT) machinery. Understanding the architecture of the native ESCRT-III complex at HIV-1 budding sites is limited due to spatial resolution and transient ESCRT-III recruitment. Here, we developed a drug-inducible transient HIV-1 budding inhibitory tool to enhance the ESCRT-III lifetime at budding sites. We generated autocleavable CHMP2A, CHMP3, and CHMP4B fusion proteins with the hepatitis C virus NS3 protease. We characterized the CHMP-NS3 fusion proteins in the absence and presence of protease inhibitor Glecaprevir with regard to expression, stability, localization, and HIV-1 Gag VLP budding. Immunoblotting experiments revealed rapid and stable accumulation of CHMP-NS3 fusion proteins. Notably, upon drug administration, CHMP2A-NS3 and CHMP4B-NS3 fusion proteins substantially decrease VLP release while CHMP3-NS3 exerted no effect but synergized with CHMP2A-NS3. Localization studies demonstrated the relocalization of CHMP-NS3 fusion proteins to the plasma membrane, endosomes, and Gag VLP budding sites. Through the combined use of transmission electron microscopy and video-microscopy, we unveiled drug-dependent accumulation of CHMP2A-NS3 and CHMP4B-NS3, causing a delay in HIV-1 Gag-VLP release. Our findings provide novel insight into the functional consequences of inhibiting ESCRT-III during HIV-1 budding and establish new tools to decipher the role of ESCRT-III at HIV-1 budding sites and other ESCRT-catalyzed cellular processes.

Blood platelets undergo several successive motor-driven reorganizations of the cytoskeleton when they are recruited to an injured part of a vessel. These reorganizations take place during the platelet activation phase, the spreading process on the injured vessel or between fibrin fibers of the forming clot, and during clot retraction. All these steps require a lot of energy, especially the retraction of the clot when platelets develop strong forces similar to those of muscle cells. Platelets can produce energy through glycolysis and mitochondrial respiration. However, although resting platelets have only 5 to 8 individual mitochondria, they produce adenosine triphosphate predominantly via oxidative phosphorylation. Activated, spread platelets show an increase in size compared with resting platelets, and the question arises as to where the few mitochondria are located in these larger platelets. Using expansion microscopy, we show that the number of mitochondria per platelet is increased in spread platelets. Live imaging and focused ion beam-scanning electron microscopy suggest that a mitochondrial fission event takes place during platelet activation. Fission is Drp1 dependent because Drp1-deficient platelets have fused mitochondria. In nucleated cells, mitochondrial fission is associated with a shift to a glycolytic phenotype, and using clot retraction assays, we show that platelets have a more glycolytic energy production during clot retraction and that Drp1-deficient platelets show a defect in clot retraction., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

The spatial organization of cell-surface receptors is fundamental for the coordination of biological responses to physical and biochemical cues of the extracellular matrix. How serine/threonine kinase receptors, ALK3-BMPRII, cooperate with integrins upon BMP2 to drive cell migration is unknown. Whether the dynamics between integrins and BMP receptors intertwine in space and time to guide adhesive processes is yet to be elucidated. We found that BMP2 stimulation controls the spatial organization of BMPRs by segregating ALK3 from BMPRII into β3 integrin-containing focal adhesions. The selective recruitment of ALK3 to focal adhesions requires β3 integrin engagement and ALK3 activation. BMP2 controls the partitioning of immobilized ALK3 within and outside focal adhesions according to single-protein tracking and super-resolution imaging. The spatial control of ALK3 in focal adhesions by optogenetics indicates that ALK3 acts as an adhesive receptor by eliciting cell spreading required for cell migration. ALK3 segregation from BMPRII in integrin-based adhesions is a key aspect of the spatio-temporal control of BMPR signaling., (© 2022 Guevara-Garcia et al.)

Virus-like particles constitute versatile vectors that can be used as vaccine platforms in many fields from infectiology and more recently to oncology. We previously designed non-infectious adenovirus-inspired 60-mer dodecahedric virus-like particles named ADDomers displaying on their surface either a short epitope or a large tumor/viral antigen. In this work, we explored for the first time the immunogenicity of ADDomers exhibiting melanoma-derived tumor antigen/epitope and their impact on the features of human dendritic cell (DC) subsets. We first demonstrated that ADDomers displaying tumor epitope/antigen elicit a strong immune-stimulating potential of human DC subsets (cDC2s, cDC1s, pDCs), which were able to internalize and cross-present tumor antigen, and subsequently cross-prime antigen-specific T-cell responses. To further limit off-target effects and enhance DC targeting, we engineered specific motifs to de-target epithelial cells and improve DCs' addressing. The improved engineered platform making it possible to display large antigen represents a tool to overcome the barrier of immune allele restriction, broadening the immune response, and paving the way to its potential utilization in humans as an off-the-shelf vaccine.

A central challenge to the biology of development and disease is deciphering how individual cells process and respond to numerous biochemical and mechanical signals originating from the environment. Recent advances in genomic studies enabled the acquisition of information about population heterogeneity; however, these so far are poorly linked with the spatial heterogeneity of biochemical and mechanical cues. Whereas in vitro models offer superior control over spatiotemporal distribution of numerous mechanical parameters, researchers are limited by the lack of methods to select subpopulations of cells in order to understand how environmental heterogeneity directs the functional collective response. To circumvent these limitations, we present a method based on the use of photo convertible proteins, which when expressed within cells and activated with light, gives a stable fluorescence fingerprint enabling subsequent sorting and lysis for genomics analysis. Using this technique, we study the spatial distribution of genetic alterations on well-characterized local mechanical stimulation within the epithelial monolayer. Our method is an in vitro alternative to laser microdissection, which so far has found a broad application in ex vivo studies.

Upon activation by different transmembrane receptors, the same signaling protein can induce distinct cellular responses. A way to decipher the mechanisms of such pleiotropic signaling activity is to directly manipulate the decision-making activity that supports the selection between distinct cellular responses. We developed an optogenetic probe (optoSRC) to control SRC signaling, an example of a pleiotropic signaling node, and we demonstrated its ability to generate different acto-adhesive structures (lamellipodia or invadosomes) upon distinct spatio-temporal control of SRC kinase activity. The occurrence of each acto-adhesive structure was simply dictated by the dynamics of optoSRC nanoclusters in adhesive sites, which were dependent on the SH3 and Unique domains of the protein. The different decision-making events regulated by optoSRC dynamics induced distinct downstream signaling pathways, which we characterized using time-resolved proteomic and network analyses. Collectively, by manipulating the molecular mobility of SRC kinase activity, these experiments reveal the pleiotropy-encoding mechanism of SRC signaling., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2021. Published by The Company of Biologists Ltd.)

Gold nanoparticles (AuNPs) have demonstrated outstanding performance in many biomedical applications. Their safety is recognised; however, their effects on the immune system remain ill defined. Antigen-presenting cells (APCs) are immune cells specialised in sensing external stimulus and in capturing exogenous materials then delivering signals for the immune responses. We used primary macrophages (Ms) and dendritic cells (DCs) of mice as an APC model. Whereas AuNPs did not alter significantly Ms and DCs functions, the exposure to AuNPs affected differently Ms and DCs in their responses to subsequent stimulations. The secretion of inflammatory molecules like cytokines (IL-6, TNF-α), chemokine (MCP-1), and reactive oxygen species (ROS) were altered differently in Ms and DCs. Furthermore, the metabolic activity of Ms was affected with the increase of mitochondrial respiration and glycolysis, while only a minor effect was seen on DCs. Antigen presentation to T cells increased when DCs were exposed to AuNPs leading to stronger Th1, Th2, and Th17 responses. In conclusion, our data provide new insights into the complexity of the effects of AuNPs on the immune system. Although AuNPs may be considered as devoid of significant effect, they may induce discrete modifications on some functions that can differ among the immune cells.

Cholesterol is a major component of mammalian plasma membranes that not only affects the physical properties of the lipid bilayer but also is the function of many membrane proteins including G protein-coupled receptors. The oxytocin receptor (OXTR) is involved in parturition and lactation of mammals and in their emotional and social behaviors. Cholesterol acts on OXTR as an allosteric modulator inducing a high-affinity state for orthosteric ligands through a molecular mechanism that has yet to be determined. Using the ion channel-coupled receptor technology, we developed a functional assay of cholesterol modulation of G protein-coupled receptors that is independent of intracellular signaling pathways and operational in living cells. Using this assay, we discovered a stable binding of cholesterol molecules to the receptor when it adopts an orthosteric ligand-bound state. This stable interaction preserves the cholesterol-dependent activity of the receptor in cholesterol-depleted membranes. This mechanism was confirmed using time-resolved FRET experiments on WT OXTR expressed in CHO cells. Consequently, a positive cross-regulation sequentially occurs in OXTR between cholesterol and orthosteric ligands., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Yes-associated protein (YAP) signaling has emerged as a crucial pathway in several normal and pathological processes. Although the main upstream effectors that regulate its activity have been extensively studied, the role of the endosomal system has been far less characterized. Here, we identified the late endosomal/lysosomal adaptor MAPK and mTOR activator (LAMTOR) complex as an important regulator of YAP signaling in a preosteoblast cell line. We found that p18/LAMTOR1-mediated peripheral positioning of late endosomes allows delivery of SRC proto-oncogene, nonreceptor tyrosine kinase (SRC) to the plasma membrane and promotes activation of an SRC-dependent signaling cascade that controls YAP nuclear shuttling. Moreover, β1 integrin engagement and mechano-sensitive cues, such as external stiffness and related cell contractility, controlled LAMTOR targeting to the cell periphery and thereby late endosome recycling and had a major impact on YAP signaling. Our findings identify the late endosome recycling pathway as a key mechanism that controls YAP activity and explains YAP mechano-sensitivity., Competing Interests: Conflict of interest—The authors declare that they have no conflicts of interest with the contents of this article., (© 2020 Block et al.)

A library of ultra-small red photoluminescent gold nanoclusters (Au NCs) were synthesized with an increasing amount of positive charges provided by the addition of mono-, di- or trivalent-glutathione modified arginine peptides. We then studied how the arginine content impacted on the interaction of Au NCs with negatively charged artificial lipid bilayers and cell membranes. Results indicated that increasing the arginine content enhanced Au NCs' adsorption on lipid bilayers and on cell membranes followed by an increased cellular uptake in melanoma cells (COLO 829). Surprisingly, the presence of up to 40% serum for highly positively charged Au NCs did not hinder their interaction with lipid bilayers that contain glycolipids, suggesting a reduced opsonization of these Au NCs. In addition, these Au NCs are usually not toxic, except those with the highest arginine contents. Thus, controlled grafting of arginine peptides onto Au NCs is an elegant strategy to improve their binding and internalization by tumor cells while still keeping their anti-fouling properties., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Chronic myelomonocytic leukemia (CMML) is a myeloid hematological malignancy with overlapping features of myelodysplastic syndromes (MDSs) and myeloproliferative neoplasms (MPNs). The knowledge of the role of the tumor microenvironment (TME), particularly mesenchymal stromal cells (MSCs), in MDS pathogenesis is increasing. Generally, cancer is associated with a procoagulant state participating in tumor development. Monocytes release procoagulant, tissue factor (TF)-bearing microparticles. We hypothesized that MSCs and clonal monocytes release procoagulant extracellular vesicles (EVs) within the CMML TME, inducing a procoagulant state that could modify hematopoietic stem cell (HSC) homeostasis. We isolated and cultured MSCs and monocytes from CMML patients and MSCs from healthy donors (HDs). Their medium EVs and small EVs (sEVs) were collected after iterative ultracentrifugations and characterized by nanoparticle tracking analysis. Their impact on hemostasis was studied with a thrombin generation assay and fibrinography. CMML or HD HSCs were exposed to sEVs from either CMML or HD MSCs. CMML MSC sEVs increased HD HSC procoagulant activity, suggesting a transfer of TF from the CMML TME to HD HSCs. The presence of TF on sEVs was shown by electron microscopy and western blot. Moreover, CMML monocyte EVs conferred a procoagulant activity to HD MSCs, which was reversed by an anti-TF antibody, suggesting the presence of TF on the EVs. Our findings revealed a procoagulant "climate" within the CMML environment related to TF-bearing sEVs secreted by CMML MSCs and monocytes., (© 2019 by The American Society of Hematology.)

Objective: We synthesized new tamoxifen derivatives as anticancer drug candidates and elaborated on convection-enhanced delivery (CED) as a strategy for delivery., Methods: To overcome the issue of their poor solubility, these ferrocenyl-tamoxifen derivatives were esterified and encapsulated into different nanocarriers, that is lipid (LNC) and polymeric nanocapsules (PNL-NC). We describe the chemistry, the encapsulation and the physicochemical characterization of these formulations., Key Findings: Starting compounds [phthalimido-ferrocidiphenol and succinimido-ferrocidiphenol], esterified prodrugs and their nanocapsules formulations were characterized. These drug candidates displayed a strong in vitro activity against breast and glioblastoma cancer cells. The ester prodrugs were toxic for glioblastoma cells (IC 50 = 9.2 × 10 -2 μm and 6.7 × 10 -2 μm, respectively). The IC 50 values for breast cancer cells were higher for these compounds. The encapsulation of the esterified compounds in LNCs (≈50 nm) or PCL-NCs (≈300 nm) did not prevent their efficacy on glioblastoma cells. These anticancer effects were due to both blockade in the S-phase of the cell cycle and apoptosis. Moreover, the tamoxifen derivatives-loaded nanocapsules induced no toxicity for healthy astrocytes and showed no haemolytic properties. Loaded Lipid Nanocapsules (LNCs) presented interesting profiles for the optimal delivery of active compounds., Conclusions: Phthalimido- and Succinimido-esters represent an innovative approach to treat cancers with cerebral localizations such as glioblastoma or brain metastases from breast cancers., (© 2018 Royal Pharmaceutical Society.)

Myelodysplastic syndromes (MDS) are oligoclonal disorders of the hematopoietic stem cells (HSC). Recurrent gene mutations are involved in the MDS physiopathology along with the medullar microenvironment. To better study the heterogeneity of MDS, it is necessary to create patient derived xenograft (PDX). We have reproduced a PDX model by xenografting HSC (CD34 + ) and mesenchymal stromal cells (MSC) in NOD/SCID/IL2rγ -/- mice with primary samples from one RAEB2, two RAEB1 and one RARS patients harboring karyotype abnormalities and gene mutations. The average human chimerisms ranged from 59.7% to 0.0175% for the 4 patients. Secondary grafts (G2) were only performed for mice derived from the RAEB2 patient and the average human chimerism was 53.33%. G1 mice 1 and 2, and their derived G2 mice showed less than 20% of medullar blasts whereas mouse 3 and the resulting G2 mice transformed to AML. Clonal architecture was dissected in the different hematopoietic progenitors (HP) harvested from G1 and G2 mice. By direct Sanger sequencing, we found the 4 initial mutations in each HP subpopulation and those mutations had the same variant allele frequency in the CD34 + CD38 - HSC from G1 and G2 mice by next generation sequencing (NGS). Targeted NGS analysis done in HSC of mouse 3 did not show any additional driver gene mutations explaining the transformation to AML. To conclude, we have generated a PDX mouse model that perfectly reproduces the MDS founder clone which is stable over time, allowing us to consider this system as a powerful tool to test therapeutic approaches., Competing Interests: CONFLICTS OF INTEREST The authors declare no major conflicts of interest.

Inherited mutations in the mitochondrial (mt)DNA are a major cause of human disease, with approximately 1 in 5000 people affected by one of the hundreds of identified pathogenic mtDNA point mutations or deletions. Due to the severe, and often untreatable, symptoms of many mitochondrial diseases, identifying how these mutations are inherited from one generation to the next has been an area of intense research in recent years. Despite large advances in our understanding of this complex process, many questions remain unanswered, with one of the most hotly debated being whether or not purifying selection acts against pathogenic mutations during germline development., (© 2018 The Authors. Development, Growth & Differentiation published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Developmental Biologists.)

Anemia is a frequent cytopenia in myelodysplastic syndromes (MDS) and most patients require red blood cell transfusion resulting in iron overload (IO). Deferasirox (DFX) has become the standard treatment of IO in MDS and it displays positive effects on erythropoiesis. In low risk MDS samples, mechanisms improving erythropoiesis after DFX treatment remain unclear. Herein, we addressed this question by using liquid cultures with iron overload of erythroid precursors treated with low dose of DFX (3μM), which corresponds to DFX 5 mg/kg/day, an unusual dose used for iron chelation. We highlight a decreased apoptosis rate and an increased proportion of cycling cells, both leading to higher proliferation rates. The iron chelation properties of low dose DFX failed to activate the Iron Regulatory Proteins and to support iron depletion, but low dose DFX dampers intracellular reactive oxygen species. Furthermore low concentrations of DFX activate the NF-κB pathway in erythroid precursors triggering anti-apoptotic and anti-inflammatory signals. Establishing stable gene silencing of the Thioredoxin (TRX) 1 genes, a NF-κB modulator, showed that fine-tuning of reactive oxygen species (ROS) levels regulates NF-κB. These results justify a clinical trial proposing low dose DFX in MDS patients refractory to erythropoiesis stimulating agents., Competing Interests: CONFLICTS OF INTEREST Sophie Park: research funding by Novartis. The remaining authors declare no conflicts of interest.

In response to metabolic or environmental stress, cells activate powerful defense mechanisms to prevent the formation and accumulation of toxic protein aggregates. The main orchestrator of this cellular response is HSF1 (heat shock factor 1), a transcription factor involved in the up-regulation of protein-coding genes with protective roles. It has become very clear that HSF1 has a broader function than initially expected. Indeed, our previous work demonstrated that, upon stress, HSF1 activates the transcription of a non-coding RNA, named Satellite III, at pericentromeric heterochromatin. Here, we observe that the function of HSF1 extends to telomeres and identify subtelomeric DNA as a new genomic target of HSF1. We show that the binding of HSF1 to subtelomeric regions plays an essential role in the upregulation of non-coding TElomeric Repeat containing RNA (TERRA) transcription upon heat shock. Importantly, our data show that telomere integrity is impacted by heat shock and that telomeric DNA damages are markedly enhanced in HSF1 deficient cells. Altogether, our findings reveal a new direct and essential function of HSF1 in the transcriptional activation of TERRA and in telomere protection upon stress., (© The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.)

[This corrects the article DOI: 10.1371/journal.pone.0172125.].

In vitro corticogenesis from embryonic stem cells (ESCs) is an attractive model of cortical development and a promising tool for cortical therapy. It is unknown to which extent epigenetic mechanisms crucial for cortex development and function, such as parental genomic imprinting, are recapitulated by in vitro corticogenesis. Here, using genome-wide transcriptomic and methylation analyses on hybrid mouse tissues and cells, we find a high concordance of imprinting status between in vivo and ESC-derived cortices. Notably, in vitro corticogenesis strictly reproduced the in vivo parent-of-origin-dependent expression of 41 imprinted genes (IGs), including Mest and Cdkn1c known to control corticogenesis. Parent-of-origin-dependent DNA methylation was also conserved at 14 of 18 imprinted differentially methylated regions. The least concordant imprinted locus was Gpr1-Zdbf2, where the aberrant bi-allelic expression of Zdbf2 and Adam23 was concomitant with a gain of methylation on the maternal allele in vitro. Combined, our data argue for a broad conservation of the epigenetic mechanisms at imprinted loci in cortical cells derived from ESCs. We propose that in vitro corticogenesis helps to define the still poorly understood mechanisms that regulate imprinting in the brain and the roles of IGs in cortical development., (© The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

The TP53 gene plays essential roles in cancer. Conventionally, wild type (WT) p53 is thought to prevent cancer development and metastasis formation, while mutant p53 has transforming abilities. However, clinical studies failed to establish p53 mutation status as an unequivocal predictive or prognostic factor of cancer progression. The recent discovery of p53 isoforms that can differentially regulate cell cycle arrest and apoptosis suggests that their expression, rather than p53 mutations, could be a more clinically relevant biomarker in patients with cancer. In this study, we show that the p53 isoform delta133p53ß is involved in regulating the apoptotic response in colorectal cancer cell lines. We first demonstrate delta133p53ß association with the small GTPase RhoB, a well-described anti-apoptotic protein. We then show that, by inhibiting RhoB activity, delta133p53ß protects cells from camptothecin-induced apoptosis. Moreover, we found that high delta133p53 mRNA expression levels are correlated with higher risk of recurrence in a series of patients with locally advanced rectal cancer (n = 36). Our findings describe how a WT TP53 isoform can act as an oncogene and add a new layer to the already complex p53 signaling network.

Organochlorine pesticides (OCPs) are widespread environmental pollutants; two of them are highly persistent: lindane (γHCH) and chlordecone (CLD). Maize plants cope with high levels of OCP-environmental pollution, however little is known about cellular mechanisms involved in plant response to such OCP-exposures. This research was aimed at understanding the physiological pathways involved in the plant response to OCPs in function of a gradient of exposure. Here we provide the evidences that OCPs might disrupt root cell cycle leading to a rise in the level of polyploidy possibly through mechanisms of endoreduplication. In addition, low-to-high doses of γHCH were able to induce an accumulation of H2O2 without modifying NO contents, while CLD modulated neither H2O2 nor NO production. [Ca(2+)]cytosolic, the caspase-3-like activity as well as TUNEL-positive nuclei and IP-positive cells increased after exposure to low-to-high doses of OCPs. These data strongly suggest a cascade mechanism of the OCP-induced toxic effect, notably with an increase in [Ca(2+)]cytosolic and caspase-3-like activity, suggesting the activation of programmed cell death pathway., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: Ca2+/calmodulin-dependent protein kinase phosphatase (CaMKP) has been proposed as a potent regulator of multifunctional Ca2+/calmodulin-dependent protein kinases (i.e., CaMKII). The CaMKII-dependent activation of myocyte enhancer factor 2 (MEF2) disrupts interactions between MEF2-histone deacetylases (HDACs), thereby de-repressing downstream gene transcription. Whether CaMKP modulates the CaMKII- MEF2 pathway in the heart is unknown. Here, we investigated the molecular and functional consequences of left ventricular (LV) pressure overload in the mouse of both genders, and in particular we evaluated the expression levels and localization of CaMKP and its association with CaMKII-MEF2 signaling., Methodology and Principal Findings: Five week-old B6D1/F1 mice of both genders underwent a sham-operation or thoracic aortic constriction (TAC). Thirty days later, TAC was associated with pathological LV hypertrophy characterized by systolic and diastolic dysfunction. Gene expression was assessed by real-time PCR. Fetal gene program re-expression comprised increased RNA levels of brain natriuretic peptide and alpha-skeletal actin. Mouse hearts of both genders expressed both CaMKP transcript and protein. Activation of signalling pathways was studied by Western blot in LV lysates or subcellular fractions (nuclear and cytoplasmic). TAC was associated with increased CaMKP expression in male LVs whereas it tended to be decreased in females. The DNA binding activity of MEF2 was determined by spectrophotometry. CaMKP compartmentalization differed according to gender. In male TAC mice, nuclear CaMKP was associated with inactive CaMKII resulting in less MEF2 activation. In female TAC mice, active CaMKII (phospho-CaMKII) detected in the nuclear fraction, was associated with a strong MEF2 transcription factor-binding activity., Conclusions/significance: Gender-specific CaMKP compartmentalization is associated with CaMKII-mediated MEF2 activation in pressure-overloaded hearts. Therefore, CaMKP could be considered as an important novel cellular target for the development of new therapeutic strategies for heart diseases.

Hypertension is a cardiovascular disorder that appears in more than half of the patients with Williams-Beuren syndrome, hemizygous for the elastin gene among 26 to 28 other genes. It was shown that the antihypertensive drug minoxidil, an ATP-dependent potassium channel opener, enhances elastic fiber formation; however, no wide clinical application was developed because of its adverse side effects. The Brown Norway rat was used here as an arterial elastin-deficient model. We tested 3 different potassium channel openers, minoxidil, diazoxide, and pinacidil, and 1 potassium channel blocker, glibenclamide, on cultured smooth muscle cells from Brown Norway rat aorta. All tested potassium channel openers increased mRNAs encoding proteins and enzymes involved in elastic fiber formation, whereas glibenclamide had the opposite effect. The higher steady-state level of tropoelastin mRNA in minoxidil-treated cells was attributable to an increase in both transcription and mRNA stability. Treatment of Brown Norway rats for 10 weeks with minoxidil or diazoxide increased elastic fiber content and decreased cell number in the aortic media, without changing collagen content. The minoxidil-induced cardiac hypertrophy was reduced when animals simultaneously received irbesartan, an angiotensin II-receptor antagonist. This side effect of minoxidil was not observed in diazoxide-treated animals. In conclusion, diazoxide, causing less undesirable side effects than minoxidil, or coadministration of minoxidil and irbesartan, increases elastic fiber content, decreases cell number in the aorta and, thus, could be suitable for treating vascular pathologies characterized by diminished arterial elastin content and simultaneous hypertension.

Chronic pressure overload (PO) induces pathological left ventricular hypertrophy (LVH) leading to congestive heart failure (HF). Overexpression of FKBP12.6 (FK506-binding protein [K]) in mice should prevent Ca2+-leak during diastole and may improve overall cardiac function. In order to decipher molecular mechanisms involved in thoracic aortic constriction (TAC)-induced cardiac remodeling and the influence of gender and genotype, we performed a proteomic analysis using two-dimensional differential in-gel electrophoresis (2D-DIGE), mass spectrometry, and bioinformatics techniques to identify alterations in characteristic biological networks. Wild-type (W) and K mice of both genders underwent TAC. Thirty days post-TAC, the altered cardiac remodeling was accompanied with systolic and diastolic dysfunction in all experimental groups. A gender difference in inflammatory protein expression (fibrinogen, α-1-antitrypsin isoforms) and in calreticulin occurred (males > females). Detoxification enzymes and cytoskeletal proteins were noticeably increased in K mice. Both non- and congestive failing mouse heart exhibited down- and upregulation of proteins related to mitochondrial function and purine metabolism, respectively. HF was characterized by a decrease in enzymes related to iron homeostasis, and altered mitochondrial protein expression related to fatty acid metabolism, glycolysis, and redox balance. Moreover, two distinct differential protein profiles characterized TAC-induced pathological LVH and congestive HF in all TAC mice. FKBP12.6 overexpression did not influence TAC-induced deleterious effects. Huntingtin was revealed as a potential mediator for HF. A broad dysregulation of signaling proteins associated with congestive HF suggested that different sets of proteins could be selected as useful biomarkers for HF progression and might predict outcome in PO-induced pathological LVH.

The involvement of erythropoietin in cardiac adaptation to acute and chronic (CHx) hypoxia was investigated in erythropoietin deficient transgenic (Epo-TAg(h)) and wild-type (WT) mice. Left (LV) and right ventricular functions were assessed by echocardiography and hemodynamics. HIF-1α, VEGF and Epo pathways were explored through RT-PCR, ELISA, Western blot and immunocytochemistry. Epo gene and protein were expressed in cardiomyocytes of WT mice in normoxia and hypoxia. Increase in blood hemoglobin, angiogenesis and functional cardiac adaptation occurred in CHx in WT mice, allowing a normal oxygen delivery (O2T). Epo deficiency induced LV hypertrophy, increased cardiac output (CO) and angiogenesis, but O2T remained lower than in WT mice. In CHx Epo-TAg(h) mice, LV hypertrophy, CO and O2T decreased. HIF-1α and Epo receptor pathways were depressed, suggesting that Epo-TAg(h) mice could not adapt to CHx despite activation of cardioprotective pathways (increased P-STAT-5/STAT-5). HIF/Epo pathway is activated in the heart of WT mice in hypoxia. Chronic hypoxia induced cardiac adaptive responses that were altered with Epo deficiency, failing to maintain oxygen delivery to tissues., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Reducing the open probability of the ryanodine receptor (RyR) has been proposed to have beneficial effects in heart failure. We investigated whether conditional FKBP12.6 overexpression at the time of myocardial infarction (MI) could improve cardiac remodelling and cell Ca(2+) handling. Wild-type (WT) mice and mice overexpressing FKBP12.6 (Tg) were studied on average 7.5 ± 0.2 weeks after MI and compared with sham-operated mice for in vivo, myocyte function and remodelling. At baseline, unloaded cell shortening in Tg was not different from WT. The [Ca(2+)](i) transient amplitude was similar, but sarcoplasmic reticulum (SR) Ca(2+) content was larger in Tg, suggesting reduced fractional release. Spontaneous spark frequency was similar despite the increased SR Ca(2+) content, consistent with a reduced RyR channel open probability in Tg. After MI, left ventricular dilatation and myocyte hypertrophy were present in both groups, but more pronounced in Tg. Cell shortening amplitude was unchanged with MI in WT, but increased with MI in Tg. The amplitude of the [Ca(2+)](i) transient was not affected by MI in either genotype, but time to peak was increased; this was most pronounced in Tg. The SR Ca(2+) content and Na(+)- Ca(2+) exchanger function were not affected by MI. Spontaneous spark frequency was increased significantly after MI in Tg, and larger than in WT (at 4 Hz, 2.6 ± 0.4 sparks (100 μm)(-1) s(-1) in Tg MI versus 1.6 ± 0.2 sparks (100 μm)(-1) s(-1) in WT MI; P < 0.05). We conclude that FKPB12.6 overexpression can effectively reduce RyR open probability with maintained cardiomyocyte contraction. However, this approach appears insufficient to prevent and reduce post-MI remodelling, indicating that additional pathways may need to be targeted.

Alterations in RyR2 function have been proposed as a major pathophysiological mechanism of arrhythmias and heart failure (HF). Cardiac FKBP12.6 overexpression protects against myocardial infarction-induced HF and catecholamine-promoted ventricular arrhythmias. We tested the hypothesis that FKBP12.6 overexpression protects against maladaptive LVH and triggered ventricular arrhythmias following transverse aorta constriction (TAC) in the mouse. The TAC-associated mortality rate was significantly lower in male transgenic (DT) than in Ctr mice (p < 0.05). TAC-associated maladaptive hypertrophy was blunted in DT mice especially 1 month post-TAC and their SERCA2a/PLB ratio remained unchanged 1 and 2 months post-TAC. Two months after TAC, trains of 30 stimuli (burst pacing) performed following isoproterenol injection (0.2 mg/kg, ip), induced VT in 50% of the TAC-Ctr and in none of the TAC-DT mice (p = 0.022). The increase in myocyte shortening and Ca(2+) spark frequency observed in sham-operated Ctr mice in response to 50 nM isoproterenol was reduced in DT mice, and abolished in TAC-DT mice. NCX1 function was reduced in Sham-DT and TAC-DT compared with Sham-Ctr and TAC-Ctr mice, respectively (p < 0.05 for the 2 comparisons). In mice killed after isoproterenol injection and burst pacing, RyR2 S2814 phosphorylation was decreased by 50% in TAC-DT versus TAC-Ctr mice (p < 0.05), with no change in RyR2 S2808 and PLB S16 and T17 phosphorylation. Cardiac FKBP12.6 overexpression in the mouse blunts pressure overload-induced maladaptive LV remodelling and protects against catecholamine-promoted burst pacing-induced ventricular tachycardia by decreasing cardiac sensitivity to adrenergic stress and RyR2 S2814 phosphorylation, and decreasing NCX1 activity.

Large arteries allow the vascular system to be more than a simple route in which the blood circulates within the organism. The elastic fibers present in the wall endow these vessels with elasticity and are responsible for the smoothing of the blood pressure and flow, which are delivered discontinuously by the heart. This function is very important to ensure appropriate hemodynamics. Elastic fibers are composed of elastin (90%) and fibrillin-rich microfibrils (10%) which provide the vessels with elasticity and are also signals able to bind to relatively specific cell membrane receptors. Stimulation of the high affinity elastin receptor by elastin peptides or tropoelastin--the elastin precursor--triggers an increase in intracellular free calcium in vascular cells, especially endothelial cells, associated with attachment, migration or proliferation. Similar effects of the stimulation of endothelial cells by microfibrils or fibrillin-1 fragments, which bind to integrins, have been demonstrated. This dual function--mechanical and in signaling--makes the elastic fibers an important actor of the development and ageing processes taking place in blood vessels. An alteration of the elastin (Eln) or fibrillin (Fbn) gene products leads to severe genetic pathologies of the cardiovascular system, such as supravalvular aortic stenosis, or Williams Beuren syndrome--in which elastin deficiency induces aortic stenoses--or Marfan syndrome, in which on the contrary fibrillin-1 deficiency promotes the appearance of aortic aneurysms. Genetically-engineered mouse models of these pathologies (such as Eln+/- mice and Fbn-1+/mgΔ mice, Eln+/-Fbn-1+/- mice) have permitted a better understanding of the pathogenesis of these syndromes. In particular, it has been shown that elastin and fibrillin-1 roles can be complementary in some aspects, while they can be opposed in some other situations. For instance, the double heterozygosity in elastin and fibrillin-1 leads to increased arterial wall stress--compared to the level induced by one of these two deficiencies alone--while the decrease in diameter induced by Eln deficiency is partly compensated by an additional deficiency in Fbn-1. Also, it is now clear that early modifications of elastin or fibrillin-1 availability can alter the normal signaling action of these proteins and lead to long term modifications of the vascular physiology and ageing processes., (© Société de Biologie, 2012.)

Preventing Ca(2+)-leak during diastole may provide a means to improve overall cardiac function. The immunosuppressant FK506-binding protein 12.6 (FKBP12.6) regulates ryanodine receptor-2 (RyR2) gating and binds to and inhibits calcineurin (Cn). It is also involved in the pathophysiology of heart failure (HF). Here, we investigated the effects of FKBP12.6 over-expression and gender on Ca(2+)-handling proteins (RyR2, SERCA2a/PLB, and NCX), and on pro-(CaMKII, Cn/NFAT) and anti-hypertrophic (GSK3β) signalling pathways in a thoracic aortic constriction (TAC) mouse model. Wild type mice (WT) and mice over-expressing FKBP12.6 of both genders underwent TAC or sham-operation (Sham). FKBP12.6 over-expression ameliorated post-TAC survival rates in both genders. Over time, FKBP12.6 over-expression reduced the molecular signature of left ventricular hypertrophy (LVH) and the transition to HF (BNP and β-MHC mRNAs) and attenuated Cn/NFAT activation in TAC-males only. The gender difference in pro- and anti-hypertrophic LVH signals was time-dependent: TAC-females exhibited earlier pathological LVH associated with concomitant SERCA2a down-regulation, CaMKII activation, and GSK3β inactivation. Both genotypes showed systolic dysfunction, possibly related to down-regulated RyR2, but only FK-TAC-males exhibited preserved diastolic LV function. Although FKBP12.6 over-expression did not impact the vicious cycle of TAC-induced HF, this study reveals some subtle sequential and temporal gender differences in Ca(2+)-signalling pathways of pathological LVH.

Fibrillin-1, the major component of extracellular microfibrils that associate with insoluble elastin in elastic fibres, is mainly synthesized during development and postnatal growth and is believed to guide elastogenesis. Mutations in the fibrillin-1 gene cause Marfan syndrome, a multisystem disorder characterized by aortic aneurysms and dissections. The recent finding that early deficiency of elastin modifies vascular ageing has raised the possibility that fibrillin-1 deficiency could also contribute to late-onset pathology of vascular remodelling. To address this question, we examined cardiovascular function in 3-week-old, 6-month-old, and 24-month-old mice that are heterozygous for a hypomorphic structural mutation of fibrillin-1 (Fbn1{+/mgΔ} mice). Our results indicate that Fbn1{+/mgΔ} mice, particularly those that are 24 months old, are slightly more hypotensive than wild-type littermates. Additionally, aneurysm and aortic insufficiency were more frequently observed in ageing Fbn1{+/mgΔ}$ mice than in the wild-type counterparts. We also noted substantial fragmentation and decreased number of elastic lamellae in the aortic wall of Fbn1{+/mgΔ} mice, which were correlated with an increase in aortic stiffness, a decrease in vasoreactivity, altered expression of elastic fibre-related genes, including fibrillin-1 and elastin, and a decrease in the relative ratio between tissue elastin and collagen. Collectively, our findings suggest that the heterozygous mgΔ mutation accelerates some aspects of vascular ageing and eventually leads to aortic manifestations resembling those of Marfan syndrome. Importantly, our data also indicate that vascular abnormalities in Fbn1{+/mgΔ} mice are opposite to those induced by elastin haploinsufficiency during ageing that affect blood pressure, vascular dimensions, and number of elastic lamellae., (Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.)

Left ventricular hypertrophy (LVH) is an adaptive response to chronic biomechanical stress that generally progresses to maladaptive hypertrophy and heart failure (HF). We studied the activation of protein kinase B (Akt/PKB), glycogen synthase kinase 3 beta (GSK3β), and calcineurin (Cn) at 3, 7, 15, 30, and 60 days following transverse aortic constriction (TAC) in 4-week-old mice. Following TAC, GSK3β inactivation at day 3 was associated with Akt activation, whereas at days 15 and 30, it appeared to be controlled by other kinases. Moderate nonsignificant Cn activation occurred at the early stages, and peak activation at day 30, concomitant with GSK3β inactivation and overt LVH and HF. At the latest stage (day 60), despite further progression of LVH and HF, Cn activation appeared attenuated. Early stages of LVH were associated with Ca2+-handling protein upregulation, whereas major Cn activation, associated with GSK3β inactivation, appeared to engage maladaptive hypertrophy and progression to HF associated with Ca2+-handling protein downregulation.

Williams-Beuren syndrome (WBS) (OMIM# 194050) is a rare, most often sporadic, genetic disease caused by a chromosomal microdeletion at locus 7q11.23 involving 28 genes. Among these, the elastin gene codes for the essential component of the arterial extracellular matrix. Developmental disorders usually associate an atypical face, cardiovascular malformations (most often supravalvular aortic stenosis and/or pulmonary artery stenosis) and a unique neuropsychological profile. This profile is defined by moderate mental retardation, relatively well-preserved language skills, visuospatial deficits and hypersociability. Other less known or rarer features, such as neonatal hypercalcemia, nutrition problems in infancy, ophthalmological anomalies, hypothyroidism, growth retardation, joint disturbances, dental anomalies and hypertension arising in adolescence or adulthood, should be treated. The aim of this paper is to summarize the major points of WBS regarding: (i) the different genes involved in the deletion and their function, especially the elastin gene and recent reports of rare forms of partial WBS or of an opposite syndrome stemming from a microduplication of the 7q11.23 locus, (ii) the clinical features in children and adults with a focus on cardiovascular injury, and (iii) the specific neuropsychological profile of people with WBS through its characteristics, the brain structures involved, and learning.

Background: Ca(2+) release from the sarcoplasmic reticulum via the ryanodine receptor (RyR2) activates cardiac myocyte contraction. An important regulator of RyR2 function is FKBP12.6, which stabilizes RyR2 in the closed state during diastole. Beta-adrenergic stimulation has been suggested to dissociate FKBP12.6 from RyR2, leading to diastolic sarcoplasmic reticulum Ca(2+) leakage and ventricular tachycardia (VT). We tested the hypothesis that FKBP12.6 overexpression in cardiac myocytes can reduce susceptibility to VT in stress conditions., Methods and Results: We developed a mouse model with conditional cardiac-specific overexpression of FKBP12.6. Transgenic mouse hearts showed a marked increase in FKBP12.6 binding to RyR2 compared with controls both at baseline and on isoproterenol stimulation (0.2 mg/kg i.p.). After pretreatment with isoproterenol, burst pacing induced VT in 10 of 23 control mice but in only 1 of 14 transgenic mice (P<0.05). In isolated transgenic myocytes, Ca(2+) spark frequency was reduced by 50% (P<0.01), a reduction that persisted under isoproterenol stimulation, whereas the sarcoplasmic reticulum Ca(2+) load remained unchanged. In parallel, peak I(Ca,L) density decreased by 15% (P<0.01), and the Ca(2+) transient peak amplitude decreased by 30% (P<0.001). A 33.5% prolongation of the caffeine-evoked Ca(2+) transient decay was associated with an 18% reduction in the Na(+)-Ca(2+) exchanger protein level (P<0.05)., Conclusions: Increased FKBP12.6 binding to RyR2 prevents triggered VT in normal hearts in stress conditions, probably by reducing diastolic sarcoplasmic reticulum Ca(2+) leak. This indicates that the FKBP12.6-RyR2 complex is an important candidate target for pharmacological prevention of VT.

Glycemia is a physiological parameter tightly regulated for an optimal energetic supply to the organism, in spite of variable tissular glucose needs. Physiopathological alteration of glycemic regulation leads to dysfunctions of many cell types. For example, diabetes considerably increases morbidity and mortality linked to cardiovascular pathologies and constitute nowadays a serious public health problem. Many in vivo and in vitro studies have investigated the impact of extracellular glucose concentration on smooth muscle and endothelial cells. Glycemia regulates expression and activity of proteins implicated in various processes, such as vasodilation (eNOS), cellular adherence (ICAM-1, VCAM-1), glucose transport (GLUT-1) or free radical generation. Nuclear receptors of the PPAR (peroxisome proliferator-activated receptors) family which are implicated in glucose and lipid metabolism control, seem to have direct vascular actions, in the regulation of cellular functions by extracellular glucose, reinforcing their status of pharmacological targets for preservation and improvement of vascular function. More general processes, such as cellular proliferation and cell death, are also influenced by glucose concentration. Concerning the contractile function, hypoglycemia and hyperglycemia modulate vascular reactivity while acting on the vasoactive substances level and the cellular response to these molecules. In particular they act on variation of ionic channels (K+, Ca2+) activity or by interfering with some signaling pathways (NO). For example, the age-dependant vasodilation and endothelial calcium influx induced by elastin peptide are modulated by extracellular glucose levels. In conclusion, abnormal chronic variations of circulating glucose levels seem to be directly responsible for endothelial and smooth muscle cell dysfunction in the pathogenesis of cardiovascular abnormalities of patients presenting glycemia dysregulations.

Supravalvular aortic stenosis is an autosomal-dominant disease of elastin (Eln) insufficiency caused by loss-of-function mutations or gene deletion. Recently, we have modeled this disease in mice (Eln+/-) and found that Eln haploinsufficiency results in unexpected changes in cardiovascular hemodynamics and arterial wall structure. Eln+/- animals were found to be stably hypertensive from birth, with a mean arterial pressure 25-30 mmHg higher than their wild-type counterparts. The animals have only moderate cardiac hypertrophy and live a normal life span with no overt signs of degenerative vascular disease. Examination of arterial mechanical properties showed that the inner diameters of Eln+/- arteries were generally smaller than wild-type arteries at any given intravascular pressure. Because the Eln+/- mouse is hypertensive, however, the effective arterial working diameter is comparable to that of the normotensive wild-type animal. Physiological studies indicate a role for the renin-angiotensin system in maintaining the hypertensive state. The association of hypertension with elastin haploinsufficiency in humans and mice strongly suggests that elastin and other proteins of the elastic fiber should be considered as causal genes for essential hypertension.

Endothelium injury is a primary event in atherogenesis, which is followed by monocyte infiltration, macrophage differentiation, and smooth muscle cell migration. Peroxisome proliferator-activated receptors (PPARs) are transcription factors now recognized as important mediators in the inflammatory response. The aim of this study was to develop a human endothelial model to evaluate anti-inflammatory properties of PPAR activators. PPAR proteins (alpha, delta and gamma) are expressed in EAhy926 endothelial cells (ECs). Pirinixic acid (Wy-14643), fenofibrate, fenofibric acid, the Merck ligand PPARdelta activator L-165041, 15-deoxy-Delta(12,14)-prostaglandin J2, but not rosiglitazone (BRL-49653) inhibited the induced expression of vascular cell adhesion molecule-1 (VCAM-1), as measured by enzyme linked immunosorbent assay (ELISA), and monocyte binding to activated-EAhy926 cells. The PPARdelta activator L-165041 had the greatest potency to reduce cytokine-induced monocyte chemotactic protein-1 (MCP-1) secretion. All PPAR activators tested which impaired VCAM-1 expression reduced significantly nuclear p65 amount. These results show that EAhy926 endothelial cells are an adequate tool to substantiate and characterize inflammatory impacts of PPAR activators.