RESUMO
The blood-brain barrier (BBB) acquires unique properties to regulate neuronal function during development. The formation of the BBB, which occurs in tandem with angiogenesis, is directed by the Wnt/ß-catenin signaling pathway. Yet the exact molecular interplay remains elusive. Our study reveals the G protein-coupled receptor GPR126 as a critical target of canonical Wnt signaling, essential for the development of the BBB's distinctive vascular characteristics and its functional integrity. Endothelial cell-specific deletion of the Gpr126 gene in mice induced aberrant vascular morphogenesis, resulting in disrupted BBB organization. Simultaneously, heightened transcytosis in vitro compromised barrier integrity, resulting in enhanced vascular permeability. Mechanistically, GPR126 enhanced endothelial cell migration, pivotal for angiogenesis, acting through an interaction between LRP1 and ß1 integrin, thereby balancing the levels of ß1 integrin activation and recycling. Overall, we identified GPR126 as a specifier of an organotypic vascular structure, which sustained angiogenesis and guaranteed the acquisition of the BBB properties during development.
Assuntos
Barreira Hematoencefálica , Integrina beta1 , Receptores Acoplados a Proteínas G , Animais , Camundongos , Barreira Hematoencefálica/metabolismo , Permeabilidade Capilar , Movimento Celular , Células Endoteliais/metabolismo , Integrina beta1/metabolismo , Integrina beta1/genética , Proteína-1 Relacionada a Receptor de Lipoproteína de Baixa Densidade/metabolismo , Proteína-1 Relacionada a Receptor de Lipoproteína de Baixa Densidade/genética , Camundongos Knockout , Neovascularização Fisiológica , Receptores Acoplados a Proteínas G/metabolismo , Receptores Acoplados a Proteínas G/genética , Via de Sinalização Wnt , Masculino , FemininoRESUMO
Glioblastomas exhibit remarkable heterogeneity at various levels, including motility modes and mechanoproperties that contribute to tumor resistance and recurrence. In a recent study using gridded micropatterns mimicking the brain vasculature, glioblastoma cell motility modes, mechanical properties, formin content, and substrate chemistry are linked. Now is presented, SP2G (SPheroid SPreading on Grids), an analytic platform designed to identify the migratory modes of patient-derived glioblastoma cells and rapidly pinpoint the most invasive sub-populations. Tumorspheres are imaged as they spread on gridded micropatterns and analyzed by this semi-automated, open-source, Fiji macro suite that characterizes migration modes accurately. SP2G can reveal intra-patient motility heterogeneity with molecular correlations to specific integrins and EMT markers. This system presents a versatile and potentially pan-cancer workflow to detect diverse invasive tumor sub-populations in patient-derived specimens and offers a valuable tool for therapeutic evaluations at the individual patient level.
RESUMO
The blood-brain barrier (BBB) is a major obstacle to the diagnostics and treatment of many central nervous system (CNS) diseases. A prime example of this challenge is seen in glioblastoma (GBM), the most aggressive and malignant primary brain tumor. The BBB in brain tumors, or the blood-brain-tumor barrier (BBTB), prevents the efficient delivery of most therapeutics to brain tumors. Current strategies to overcome the BBB for therapeutic delivery, such as using hyperosmotic agents (mannitol), have impeded progress in clinical translation limited by the lack of spatial resolution, high incidences of complications, and potential for toxicity. Focused ultrasound combined with intravenously administered microbubbles enables the transient disruption of the BBB and has progressed to early-phase clinical trials. However, the poor survival with currently approved treatments for GBM highlights the compelling need to develop and validate treatment strategies as well as the screening for more potent anticancer drugs. In this protocol, we introduce an optical method to open the BBTB (OptoBBTB) for therapeutic delivery via ultrashort pulse laser stimulation of vascular targeting plasmonic gold nanoparticles (AuNPs). Specifically, the protocol includes the synthesis and characterization of vascular-targeting AuNPs and a detailed procedure of optoBBTB. We also report the downstream characterization of the drug delivery and tumor treatment efficacy after BBB modulation. Compared with other barrier modulation methods, our optical approach has advantages in high spatial resolution and minimally invasive access to tissues. Overall, optoBBTB allows for the delivery of a variety of therapeutics into the brain and will accelerate drug delivery and screening for CNS disease treatment. Key features ⢠Pulsed laser excitation of vascular-targeting gold nanoparticles non-invasively and reversibly modulates the blood-brain barrier permeability. ⢠OptoBBTB enhances drug delivery in clinically relevant glioblastoma models. ⢠OptoBBTB has the potential for drug screening and evaluation for superficial brain tumor treatment.
RESUMO
The treatment of glioblastoma has limited clinical progress over the past decade, partly due to the lack of effective drug delivery strategies across the blood-brain-tumor barrier. Moreover, discrepancies between preclinical and clinical outcomes demand a reliable translational platform that can precisely recapitulate the characteristics of human glioblastoma. Here we analyze the intratumoral blood-brain-tumor barrier heterogeneity in human glioblastoma and characterize two genetically engineered models in female mice that recapitulate two important glioma phenotypes, including the diffusely infiltrative tumor margin and angiogenic core. We show that pulsed laser excitation of vascular-targeted gold nanoparticles non-invasively and reversibly modulates the blood-brain-tumor barrier permeability (optoBBTB) and enhances the delivery of paclitaxel in these two models. The treatment reduces the tumor volume by 6 and 2.4-fold and prolongs the survival by 50% and 33%, respectively. Since paclitaxel does not penetrate the blood-brain-tumor barrier and is abandoned for glioblastoma treatment following its failure in early-phase clinical trials, our results raise the possibility of reevaluating a number of potent anticancer drugs by combining them with strategies to increase blood-brain-tumor barrier permeability. Our study reveals that optoBBTB significantly improves therapeutic delivery and has the potential to facilitate future drug evaluation for cancers in the central nervous system.
Assuntos
Neoplasias Encefálicas , Glioblastoma , Nanopartículas Metálicas , Nanopartículas , Humanos , Feminino , Animais , Camundongos , Barreira Hematoencefálica , Glioblastoma/tratamento farmacológico , Glioblastoma/patologia , Ouro/farmacologia , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/patologia , Paclitaxel/farmacologia , Paclitaxel/uso terapêutico , Sistemas de Liberação de Medicamentos/métodos , Linhagem Celular TumoralRESUMO
The blood-brain barrier (BBB) maintains an optimal environment for brain homeostasis but excludes most therapeutics from entering the brain. Strategies that reversibly increase BBB permeability are essential for treating brain diseases and are the focus of significant preclinical and translational interest. Picosecond laser excitation of tight junction-targeted gold nanoparticles (AuNPs) generates a nanoscale mechanical perturbation and induces a graded and reversible increase in BBB permeability (OptoBBB). Here we advanced this technique by showing that targeting endothelial glycoproteins leads to >10-fold higher targeting efficiency than targeting tight junctions both in vitro and in vivo. With both tight-junction and glycoprotein targeting, we demonstrate that OptoBBB is associated with a transient elevation and propagation of Ca2+, actin polymerization, and phosphorylation of ERK1/2 (extracellular signal-regulated protein kinase). These collectively activate the cytoskeleton resulting in increased paracellular permeability. The Ca2+ response involves internal Ca2+ depletion and Ca2+ influx with contributions from mechanosensitive ion channels (TRPV4, Piezo1). We provide insight into how the excitation of tight junction protein (JAM-A)-targeted and endothelial (glycocalyx)-targeted AuNPs leads to similar mechanobiological modulation of BBB permeability while targeting the glycocalyx significantly improves the nanoparticle accumulation in the brain. The results will be critical for guiding the future development of this technology for brain disease treatment.
Assuntos
Barreira Hematoencefálica , Nanopartículas Metálicas , Barreira Hematoencefálica/metabolismo , Ouro/farmacologia , Ouro/metabolismo , Encéfalo/metabolismo , PermeabilidadeRESUMO
Glioblastoma are heterogeneous tumors composed of highly invasive and highly proliferative clones. Heterogeneity in invasiveness could emerge from discrete biophysical properties linked to specific molecular expression. We identified clones of patient-derived glioma propagating cells that were either highly proliferative or highly invasive and compared their cellular architecture, migratory, and biophysical properties. We discovered that invasiveness was linked to cellular fitness. The most invasive cells were stiffer, developed higher mechanical forces on the substrate, and moved stochastically. The mechano-chemical-induced expression of the formin FMN1 conferred invasive strength that was confirmed in patient samples. Moreover, FMN1 expression was also linked to motility in other cancer and normal cell lines, and its ectopic expression increased fitness parameters. Mechanistically, FMN1 acts from the microtubule lattice and promotes a robust mechanical cohesion, leading to highly invasive motility.
Assuntos
Movimento Celular/fisiologia , Forminas/metabolismo , Glioblastoma/metabolismo , Invasividade Neoplásica/patologia , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Proteínas Fetais/metabolismo , Glioblastoma/patologia , Humanos , Proteínas dos Microfilamentos/metabolismoRESUMO
The blood-brain barrier (BBB) is highly selective and acts as the interface between the central nervous system and circulation. While the BBB is critical for maintaining brain homeostasis, it represents a formidable challenge for drug delivery. Here we synthesized gold nanoparticles (AuNPs) for targeting the tight junction specifically and demonstrated that transcranial picosecond laser stimulation of these AuNPs post intravenous injection increases the BBB permeability. The BBB permeability change can be graded by laser intensity, is entirely reversible, and involves increased paracellular diffusion. BBB modulation does not lead to significant disruption in the spontaneous vasomotion or the structure of the neurovascular unit. This strategy allows the entry of immunoglobulins and viral gene therapy vectors, as well as cargo-laden liposomes. We anticipate this nanotechnology to be useful for tissue regions that are accessible to light or fiberoptic application and to open new avenues for drug screening and therapeutic interventions in the central nervous system.
Assuntos
Nanopartículas Metálicas , Nanopartículas , Transporte Biológico , Barreira Hematoencefálica , Ouro/química , LasersRESUMO
Endothelial-to-mesenchymal transition (EndMT) is the biological process through which endothelial cells transdifferentiate into mesenchymal cells. During embryo development, EndMT regulates endocardial cushion formation via TGFß/BMP signaling. In adults, EndMT is mainly activated during pathological conditions. Hence, it is necessary to characterize molecular regulators cooperating with TGFß signaling in driving EndMT, to identify potential novel therapeutic targets to treat these pathologies. Here, we studied YAP, a transcriptional co-regulator involved in several biological processes, including epithelial-to-mesenchymal transition (EMT). As EndMT is the endothelial-specific form of EMT, and YAP (herein referring to YAP1) and TGFß signaling cross-talk in other contexts, we hypothesized that YAP contributes to EndMT by modulating TGFß signaling. We demonstrate that YAP is required to trigger TGFß-induced EndMT response, specifically contributing to SMAD3-driven EndMT early gene transcription. We provide novel evidence that YAP acts as SMAD3 transcriptional co-factor and prevents GSK3ß-mediated SMAD3 phosphorylation, thus protecting SMAD3 from degradation. YAP is therefore emerging as a possible candidate target to inhibit pathological TGFß-induced EndMT at early stages.
Assuntos
Células Endoteliais , Fator de Crescimento Transformador beta , Células Endoteliais/metabolismo , Transição Epitelial-Mesenquimal , Fosforilação , Fator de Crescimento Transformador beta/metabolismoRESUMO
In some organs, such as the brain, endothelial cells form a robust and highly selective blood-to-tissue barrier. However, in other organs, such as the intestine, endothelial cells provide less stringent permeability, to allow rapid exchange of solutes and nutrients where needed. To maintain the structural and functional integrity of the highly dynamic blood-brain and gut-vascular barriers, endothelial cells form highly specialized cell-cell junctions, known as adherens junctions and tight junctions. Claudins are a family of four-membrane-spanning proteins at tight junctions and they have both barrier-forming and pore-forming properties. Tissue-specific expression of claudins has been linked to different diseases that are characterized by barrier impairment. In this review, we summarize the more recent progress in the field of the claudins, with particular attention to their expression and function in the blood-brain barrier and the recently described gut-vascular barrier, under physiological and pathological conditions.Abbreviations: 22q11DS 22q11 deletion syndrome; ACKR1 atypical chemokine receptor 1; AD Alzheimer disease; AQP aquaporin; ATP adenosine triphosphate; Aß amyloid ß; BAC bacterial artificial chromosome; BBB blood-brain barrier; C/EBP-α CCAAT/enhancer-binding protein α; cAMP cyclic adenosine monophosphate (or 3',5'-cyclic adenosine monophosphate); CD cluster of differentiation; CNS central nervous system; DSRED discosoma red; EAE experimental autoimmune encephalomyelitis; ECV304 immortalized endothelial cell line established from the vein of an apparently normal human umbilical cord; EGFP enhanced green fluorescent protein; ESAM endothelial cell-selective adhesion molecule; GLUT-1 glucose transporter 1; GVB gut-vascular barrier; H2B histone H2B; HAPP human amyloid precursor protein; HEK human embryonic kidney; JACOP junction-associated coiled coil protein; JAM junctional adhesion molecules; LYVE1 lymphatic vessel endothelial hyaluronan receptor 1; MADCAM1 mucosal vascular addressin cell adhesion molecule 1; MAPK mitogen-activated protein kinase; MCAO middle cerebral artery occlusion; MMP metalloprotease; MS multiple sclerosis; MUPP multi-PDZ domain protein; PATJ PALS-1-associated tight junction protein; PDGFR-α platelet-derived growth factor receptor α polypeptide; PDGFR-ß platelet-derived growth factor receptor ß polypeptide; RHO rho-associated protein kinase; ROCK rho-associated, coiled-coil-containing protein kinase; RT-qPCR real time quantitative polymerase chain reactions; PDGFR-ß soluble platelet-derived growth factor receptor, ß polypeptide; T24 human urinary bladder carcinoma cells; TG2576 transgenic mice expressing the human amyloid precursor protein; TNF-α tumor necrosis factor α; WTwild-type; ZO zonula occludens.
Assuntos
Claudinas , Células Endoteliais , Peptídeos beta-Amiloides , Animais , Encéfalo , Camundongos , Junções ÍntimasRESUMO
RATIONALE: Intercellular tight junctions are crucial for correct regulation of the endothelial barrier. Their composition and integrity are affected in pathological contexts, such as inflammation and tumor growth. JAM-A (junctional adhesion molecule A) is a transmembrane component of tight junctions with a role in maintenance of endothelial barrier function, although how this is accomplished remains elusive. OBJECTIVE: We aimed to understand the molecular mechanisms through which JAM-A expression regulates tight junction organization to control endothelial permeability, with potential implications under pathological conditions. METHODS AND RESULTS: Genetic deletion of JAM-A in mice significantly increased vascular permeability. This was associated with significantly decreased expression of claudin-5 in the vasculature of various tissues, including brain and lung. We observed that C/EBP-α (CCAAT/enhancer-binding protein-α) can act as a transcription factor to trigger the expression of claudin-5 downstream of JAM-A, to thus enhance vascular barrier function. Accordingly, gain-of-function for C/EBP-α increased claudin-5 expression and decreased endothelial permeability, as measured by the passage of fluorescein isothiocyanate (FITC)-dextran through endothelial monolayers. Conversely, C/EBP-α loss-of-function showed the opposite effects of decreased claudin-5 levels and increased endothelial permeability. Mechanistically, JAM-A promoted C/EBP-α expression through suppression of ß-catenin transcriptional activity, and also through activation of EPAC (exchange protein directly activated by cAMP). C/EBP-α then directly binds the promoter of claudin-5 to thereby promote its transcription. Finally, JAM-A-C/EBP-α-mediated regulation of claudin-5 was lost in blood vessels from tissue biopsies from patients with glioblastoma and ovarian cancer. CONCLUSIONS: We describe here a novel role for the transcription factor C/EBP-α that is positively modulated by JAM-A, a component of tight junctions that acts through EPAC to up-regulate the expression of claudin-5, to thus decrease endothelial permeability. Overall, these data unravel a regulatory molecular pathway through which tight junctions limit vascular permeability. This will help in the identification of further therapeutic targets for diseases associated with endothelial barrier dysfunction. Graphic Abstract: An graphic abstract is available for this article.
Assuntos
Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Permeabilidade Capilar , Moléculas de Adesão Celular/metabolismo , Claudina-5/metabolismo , Células Endoteliais/metabolismo , Receptores de Superfície Celular/metabolismo , Junções Íntimas/metabolismo , Adulto , Idoso , Animais , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patologia , Proteínas Estimuladoras de Ligação a CCAAT/genética , Moléculas de Adesão Celular/genética , Linhagem Celular , Claudina-5/genética , Feminino , Glioblastoma/metabolismo , Glioblastoma/patologia , Humanos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , Neovascularização Patológica , Neoplasias Ovarianas/metabolismo , Neoplasias Ovarianas/patologia , Receptores de Superfície Celular/genética , Transdução de Sinais , Junções Íntimas/genética , Regulação para CimaRESUMO
Precise manipulation of protein activity in living systems has broad applications in biomedical sciences. However, it is challenging to use light to manipulate protein activity in living systems without genetic modification. Here, we report a technique to optically switch off protein activity in living cells with high spatiotemporal resolution, referred to as molecular hyperthermia (MH). MH is based on the nanoscale-confined heating of plasmonic gold nanoparticles by short laser pulses to unfold and photoinactivate targeted proteins of interest. First, we show that protease-activated receptor 2 (PAR2), a G-protein-coupled receptor and an important pathway that leads to pain sensitization, can be photoinactivated in situ by MH without compromising cell proliferation. PAR2 activity can be switched off in laser-targeted cells without affecting surrounding cells. Furthermore, we demonstrate the molecular specificity of MH by inactivating PAR2 while leaving other receptors intact. Second, we demonstrate that the photoinactivation of a tight junction protein in brain endothelial monolayers leads to a reversible blood-brain barrier opening in vitro. Lastly, the protein inactivation by MH is below the nanobubble generation threshold and thus is predominantly due to the nanoscale heating. MH is distinct from traditional hyperthermia (that induces global tissue heating) in both its time and length scales: nanoseconds versus seconds, nanometers versus millimeters. Our results demonstrate that MH enables selective and remote manipulation of protein activity and cellular behavior without genetic modification.
Assuntos
Temperatura Alta , Proteínas de Membrana , Nanopartículas Metálicas/química , Óptica e Fotônica/métodos , Barreira Hematoencefálica/química , Linhagem Celular , Ouro/química , Humanos , Lasers , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Proteínas de Membrana/efeitos da radiação , Receptores Acoplados a Proteínas G/química , Receptores Acoplados a Proteínas G/metabolismo , Receptores Acoplados a Proteínas G/efeitos da radiaçãoRESUMO
Cerebral cavernous malformation (CCM) is a neurovascular familial or sporadic disease that is characterised by capillary-venous cavernomas, and is due to loss-of-function mutations to any one of three CCM genes. Familial CCM follows a two-hit mechanism similar to that of tumour suppressor genes, while in sporadic cavernomas only a small fraction of endothelial cells shows mutated CCM genes. We reported that in mouse models and in human patients, endothelial cells lining the lesions have different features from the surrounding endothelium, as they express mesenchymal/stem-cell markers. Here we show that cavernomas originate from clonal expansion of few Ccm3-null endothelial cells that express mesenchymal/stem-cell markers. These cells then attract surrounding wild-type endothelial cells, inducing them to express mesenchymal/stem-cell markers and to contribute to cavernoma growth. These characteristics of Ccm3-null cells are reminiscent of the tumour-initiating cells that are responsible for tumour growth. Our data support the concept that CCM has benign tumour characteristics.
Assuntos
Proteínas Reguladoras de Apoptose/genética , Neoplasias do Sistema Nervoso Central/patologia , Células Endoteliais/patologia , Hemangioma Cavernoso do Sistema Nervoso Central/patologia , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas de Membrana/genética , Proteínas Proto-Oncogênicas/genética , Animais , Proteínas Reguladoras de Apoptose/metabolismo , Biomarcadores/metabolismo , Encéfalo/irrigação sanguínea , Encéfalo/citologia , Encéfalo/patologia , Diferenciação Celular/genética , Linhagem Celular , Neoplasias do Sistema Nervoso Central/genética , Modelos Animais de Doenças , Células Endoteliais/metabolismo , Endotélio Vascular/citologia , Endotélio Vascular/patologia , Feminino , Técnicas de Inativação de Genes , Hemangioma Cavernoso do Sistema Nervoso Central/genética , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Mutação com Perda de Função , Proteínas de Membrana/metabolismo , Células-Tronco Mesenquimais/metabolismo , Camundongos , Camundongos Knockout , Proteínas Proto-Oncogênicas/metabolismoRESUMO
BACKGROUND: The tumour microenvironment is a critical regulator of malignant cancer progression. While endothelial cells have been widely studied in the context of tumour angiogenesis, their role as modulators of cancer cell invasion and migration is poorly understood. METHODS: We have investigated the influence of endothelial cells on the invasive and migratory behaviour of human cancer cells in vitro. RESULTS: Upon exposure to culture supernatants of endothelial cells, distinct cancer cells, such as SK-BR-3 cells, showed significantly increased invasion and cell migration concomitant with changes in cell morphology and gene expression reminiscent of an epithelial-mesenchymal transition (EMT). Interestingly, the pro-migratory effect on SK-BR-3 cells was significantly enhanced by supernatants obtained from subconfluent, proliferative endothelial cells rather than from confluent, quiescent endothelial cells. Systematically comparing the supernatants of subconfluent and confluent endothelial cells by quantitative MS proteomics revealed eight candidate proteins that were secreted at significantly higher levels by confluent endothelial cells representing potential inhibitors of cancer cell migration. Among these proteins, nidogen-1 was exclusively expressed in confluent endothelial cells and was found to be necessary and sufficient for the inhibition of SK-BR-3 cell migration. Indeed, SK-BR-3 cells exposed to nidogen-1-depleted endothelial supernatants showed increased promigratory STAT3 phosphorylation along with increased cell migration. This reflects the situation of enhanced SK-BR-3 migration upon stimulation with conditioned medium from subconfluent endothelial cells with inherent absence of nidogen-1 expression. CONCLUSION: The identification of nidogen-1 as an endothelial-derived inhibitor of migration of distinct cancer cell types reveals a novel mechanism of endothelial control over cancer progression.
Assuntos
Neoplasias da Mama/patologia , Células Endoteliais/metabolismo , Glicoproteínas de Membrana/metabolismo , Microambiente Tumoral , Neoplasias da Mama/genética , Linhagem Celular Tumoral , Movimento Celular/fisiologia , Proliferação de Células/fisiologia , Transição Epitelial-Mesenquimal/fisiologia , Feminino , Regulação Neoplásica da Expressão Gênica , Células Endoteliais da Veia Umbilical Humana , Humanos , Glicoproteínas de Membrana/genética , Invasividade Neoplásica/patologia , Fosforilação , Cultura Primária de Células , RNA Interferente Pequeno/metabolismo , Fator de Transcrição STAT3/metabolismoRESUMO
The KDEL receptor (KDELR) is a seven-transmembrane-domain protein involved in retrograde transport of protein chaperones from the Golgi complex to the endoplasmic reticulum. Our recent findings have shown that the Golgi-localised KDELR acts as a functional G-protein-coupled receptor by binding to and activating Gs and Gq. These G proteins induce activation of PKA and Src and regulate retrograde and anterograde Golgi trafficking. Here we used an integrated coimmunoprecipitation and mass spectrometry approach to identify prohibitin-1 (PHB) as a KDELR interactor. PHB is a multifunctional protein that is involved in signal transduction, cell-cycle control, and stabilisation of mitochondrial proteins. We provide evidence that depletion of PHB induces intense membrane-trafficking activity at the ER-Golgi interface, as revealed by formation of GM130-positive Golgi tubules, and recruitment of p115, ß-COP, and GBF1 to the Golgi complex. There is also massive recruitment of SEC31 to endoplasmic-reticulum exit sites. Furthermore, absence of PHB decreases the levels of the Golgi-localised KDELR, thus preventing KDELR-dependent activation of Golgi-Src and inhibiting Golgi-to-plasma-membrane transport of VSVG. We propose a model whereby in analogy to previous findings (e.g., the RAS-RAF signalling pathway), PHB can act as a signalling scaffold protein to assist in KDELR-dependent Src activation.
Assuntos
Transporte Proteico/genética , Receptores de Peptídeos/metabolismo , Proteínas Repressoras/metabolismo , Quinases da Família src/genética , Animais , Células COS , Chlorocebus aethiops , Retículo Endoplasmático/genética , Retículo Endoplasmático/metabolismo , Complexo de Golgi/genética , Complexo de Golgi/metabolismo , Células HeLa , Humanos , Proibitinas , Ligação Proteica , Receptores de Peptídeos/genética , Proteínas Repressoras/genética , Transdução de SinaisRESUMO
Mesoangioblasts are vessel-associated progenitor cells that show therapeutic promise for the treatment of muscular dystrophy. Mesoangioblasts have the ability to undergo skeletal muscle differentiation and cross the blood vessel wall regardless of the developmental stage at which they are isolated. Here we show that PW1/Peg3 is expressed at high levels in mesoangioblasts obtained from mouse, dog and human tissues and its level of expression correlates with their myogenic competence. Silencing PW1/Peg3 markedly inhibits myogenic potential of mesoangioblasts in vitro through MyoD degradation. Moreover, lack of PW1/Peg3 abrogates mesoangioblast ability to cross the vessel wall and to engraft into damaged myofibres through the modulation of the junctional adhesion molecule-A. We conclude that PW1/Peg3 function is essential for conferring proper mesoangioblast competence and that the determination of PW1/Peg3 levels in human mesoangioblasts may serve as a biomarker to identify the best donor populations for therapeutic application in muscular dystrophies.
Assuntos
Biomarcadores/metabolismo , Vasos Sanguíneos/citologia , Fatores de Transcrição Kruppel-Like/metabolismo , Células-Tronco/fisiologia , Animais , Western Blotting , Células Cultivadas , Imunoprecipitação da Cromatina , Primers do DNA/genética , Cães , Inativação Gênica , Vetores Genéticos/genética , Humanos , Fatores de Transcrição Kruppel-Like/genética , Luciferases , Camundongos , Microscopia de Fluorescência , Desenvolvimento Muscular/fisiologia , Distrofias Musculares/terapia , Proteína MyoD/metabolismo , Retroviridae , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Protein mono-ADP-ribosylation is a reversible post-translational modification of cellular proteins. This scheme of amino-acid modification is used not only by bacterial toxins to attack host cells, but also by endogenous ADP-ribosyltransferases (ARTs) in mammalian cells. These latter ARTs include members of three different families of proteins: the well characterised arginine-specific ecto-enzymes (ARTCs), two sirtuins, and some members of the poly(ADP-ribose) polymerase (PARP/ARTD) family. In the present study, we demonstrate that human ARTC1 is localised to the endoplasmic reticulum (ER), in contrast to the previously characterised ARTC proteins, which are typical GPI-anchored ecto-enzymes. Moreover, using the "macro domain" cognitive binding module to identify ADP-ribosylated proteins, we show here that the ER luminal chaperone GRP78/BiP (glucose-regulated protein of 78 kDa/immunoglobulin heavy-chain-binding protein) is a cellular target of human ARTC1 and hamster ARTC2. We further developed a procedure to visualise ADP-ribosylated proteins using immunofluorescence. With this approach, in cells overexpressing ARTC1, we detected staining of the ER that co-localises with GRP78/BiP, thus confirming that this modification occurs in living cells. In line with the key role of GRP78/BiP in the ER stress response system, we provide evidence here that ARTC1 is activated during the ER stress response, which results in acute ADP-ribosylation of GRP78/BiP paralleling translational inhibition. Thus, this identification of ARTC1 as a regulator of GRP78/BiP defines a novel, previously unsuspected, player in GRP78-mediated ER stress responses.
Assuntos
ADP Ribose Transferases/metabolismo , Estresse do Retículo Endoplasmático , Proteínas de Choque Térmico/metabolismo , ADP Ribose Transferases/análise , Animais , Células CHO , Cricetinae , Cricetulus , Retículo Endoplasmático/metabolismo , Retículo Endoplasmático/ultraestrutura , Chaperona BiP do Retículo Endoplasmático , Proteínas Ligadas por GPI/análise , Proteínas Ligadas por GPI/metabolismo , Células HEK293 , Células HeLa , Proteínas de Choque Térmico/análise , HumanosRESUMO
A fundamental property of cellular processes is to maintain homeostasis despite varying internal and external conditions. Within the membrane transport apparatus, variations in membrane fluxes from the endoplasmic reticulum (ER) to the Golgi complex are balanced by opposite fluxes from the Golgi to the ER to maintain homeostasis between the two organelles. Here we describe a molecular device that balances transport fluxes by integrating transduction cascades with the transport machinery. Specifically, ER-to-Golgi transport activates the KDEL receptor at the Golgi, which triggers a cascade that involves Gs and adenylyl cyclase and phosphodiesterase isoforms and then PKA activation and results in the phosphorylation of transport machinery proteins. This induces retrograde traffic to the ER and balances transport fluxes between the ER and Golgi. Moreover, the KDEL receptor activates CREB1 and other transcription factors that upregulate transport-related genes. Thus, a Golgi-based control system maintains transport homeostasis through both signaling and transcriptional networks.
Assuntos
Retículo Endoplasmático/metabolismo , Complexo de Golgi/metabolismo , Receptores de Peptídeos/metabolismo , Animais , Transporte Biológico/fisiologia , Linhagem Celular , Homeostase/fisiologia , Humanos , Camundongos , Fosforilação , Transdução de Sinais/fisiologiaRESUMO
Muscular dystrophies are severe genetic diseases for which no efficacious therapies exist. Experimental clinical treatments include intra-arterial administration of vessel-associated stem cells, called mesoangioblasts (MABs). However, one of the limitations of this approach is the relatively low number of cells that engraft the diseased tissue, due, at least in part, to the sub-optimal efficiency of extravasation, whose mechanisms for MAB are unknown. Leukocytes emigrate into the inflamed tissues by crossing endothelial cell-to-cell junctions and junctional proteins direct and control leukocyte diapedesis. Here, we identify the endothelial junctional protein JAM-A as a key regulator of MAB extravasation. We show that JAM-A gene inactivation and JAM-A blocking antibodies strongly enhance MAB engraftment in dystrophic muscle. In the absence of JAM-A, the exchange factors EPAC-1 and 2 are down-regulated, which prevents the activation of the small GTPase Rap-1. As a consequence, junction tightening is reduced, allowing MAB diapedesis. Notably, pharmacological inhibition of Rap-1 increases MAB engraftment in dystrophic muscle, which results into a significant improvement of muscle function offering a novel strategy for stem cell-based therapies.
Assuntos
Moléculas de Adesão Celular/metabolismo , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Distrofias Musculares/terapia , Receptores de Superfície Celular/metabolismo , Transdução de Sinais , Transplante de Células-Tronco , Células-Tronco/citologia , Proteínas rap1 de Ligação ao GTP/metabolismo , Animais , Cardiotoxinas , Moléculas de Adesão Celular/antagonistas & inibidores , Moléculas de Adesão Celular/deficiência , Movimento Celular , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Endotélio Vascular/metabolismo , Endotélio Vascular/patologia , Humanos , Camundongos , Músculo Esquelético/lesões , Músculo Esquelético/patologia , Distrofias Musculares/patologia , Distrofias Musculares/cirurgia , Receptores de Superfície Celular/antagonistas & inibidores , Receptores de Superfície Celular/deficiência , Sarcoglicanas/deficiência , Sarcoglicanas/metabolismoRESUMO
Classical signal transduction is initiated at the plasma membrane by extracellular signals and propagates to the cytosolic face of the same membrane. Multiple studies have shown that endomembranes can act as signaling platforms for this plasma-membrane-originated signaling. Recent evidence has indicated that endomembranes can also trigger their own signaling cascades that involve some of the molecular players that are classically engaged in signal transduction at the plasma membrane. Endomembrane-initiated signaling is important for synchronization of the functioning of the secretory pathway and coordination of the activities of the secretory organelles with other cellular machineries. However, these endomembrane-initiated regulatory circuits are only partially understood to date. This novel field is slowed by a lack of specific tools and the objective difficulties in the study of signal transduction of endomembrane-localized receptors, as their accessibility is limited. For example, the ligand-binding site of the KDEL receptor (that transduces endomembrane signaling) is positioned in the lumen of the Golgi complex. Here we report some approaches that are suitable for the study of endomembrane-initiated signaling.
Assuntos
Membrana Celular/metabolismo , Retículo Endoplasmático/metabolismo , Fibroblastos/metabolismo , Complexo de Golgi/metabolismo , Transdução de Sinais/genética , Autoantígenos/genética , Autoantígenos/metabolismo , Transporte Biológico , Western Blotting , Células Cultivadas , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Colágeno Tipo IV/genética , Colágeno Tipo IV/metabolismo , Fibroblastos/citologia , Transferência Ressonante de Energia de Fluorescência , Regulação da Expressão Gênica , Genes Reporter , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Células HeLa , Humanos , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Microscopia de Fluorescência , Fosforilação , Tirosina/metabolismo , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/metabolismo , Proteína Vermelha FluorescenteRESUMO
VE-cadherin is a component of endothelial cell-to-cell adherens junctions, and it has a key role in the maintenance of vascular integrity. During embryo development, VE-cadherin is required for the organization of a stable vascular system, and in the adult it controls vascular permeability and inhibits unrestrained vascular growth. The mechanisms of action of VE-cadherin are complex and include reshaping and organization of the endothelial cell cytoskeleton and modulation of gene transcription. Here we review some of the most important pathways through which VE-cadherin modulates vascular homeostasis and discuss the emerging concepts in the overall biological role of this protein.