Maria Grazia Lampugnani - Academia.edu (original) (raw)

Papers by Maria Grazia Lampugnani

Circulation Research, 2017

Correct organization of the vascular tree requires the balanced activities of several signaling p... more Correct organization of the vascular tree requires the balanced activities of several signaling pathways that regulate tubulogenesis and vascular branching, elongation, and pruning. When this balance is lost, the vessels can be malformed and fragile, and they can lose arteriovenous differentiation. In this review, we concentrate on the transforming growth factor (TGF)-β/bone morphogenetic protein (BMP) pathway, which is one of the most important and complex signaling systems in vascular development. Inactivation of these pathways can lead to altered vascular organization in the embryo. In addition, many vascular malformations are related to deregulation of TGF-β/BMP signaling. Here, we focus on two of the most studied vascular malformations that are induced by deregulation of TGF-β/BMP signaling: hereditary hemorrhagic telangiectasia (HHT) and cerebral cavernous malformation (CCM). The first of these is related to loss-of-function mutation of the TGF-β/BMP receptor complex and the s...

Science, 2018

Are endothelial-to-mesenchymal transitions in various vascular pathologies a consequence, cause, ... more Are endothelial-to-mesenchymal transitions in various vascular pathologies a consequence, cause, or defense?

The FASEB Journal, 1995

The endothelium forms the main barrier to the passage of macromolecules and circulating cells fro... more The endothelium forms the main barrier to the passage of macromolecules and circulating cells from blood to tissues. Endothelial permeability is in large part regulated by intercellular junctions. These are complex structures formed by transmembrane adhesive molecules linked to a network of cytoplasmic/cytoskeletal proteins. At least four different types of endothelial junctions have been described: tight junctions, gap junctions, adherence junctions and syndesmos.

Journal of Cell Biology, 1989

Von Willebrand factor (vWF) is a constitutive and specific component of endothelial cell (EC) mat... more Von Willebrand factor (vWF) is a constitutive and specific component of endothelial cell (EC) matrix. In this paper we show that, in vitro, vWF can induce EC adhesion and promote organization of microfilaments and adhesion plaques. In contrast, human vascular smooth muscle cells and MG63 osteosarcoma cells did not adhere and spread on vWF. Using antibodies to the beta chains of fibronectin (beta 1) and vitronectin (beta 3) receptors it was found that ECs adherent to vWF show clustering of both receptors. The beta 1 receptor antibodies are arranged along stress fibers at sites of extracellular matrix contact while the beta 3 receptor antibodies were sharply confined at adhesion plaques. ECs release and organize endogenous fibronectin early during adhesion to vWF. Upon blocking protein synthesis and secretion, ECs can equally adhere and spread on vWF but, while the beta 3 receptors are regularly organized, the beta 1 receptors remain diffuse. This suggests that the organization of the...

The Journal of cell biology, Jan 21, 2015

Vascular endothelial (VE)-cadherin transfers intracellular signals contributing to vascular hemos... more Vascular endothelial (VE)-cadherin transfers intracellular signals contributing to vascular hemostasis. Signaling through VE-cadherin requires association and activity of different intracellular partners. Yes-associated protein (YAP)/TAZ transcriptional cofactors are important regulators of cell growth and organ size. We show that EPS8, a signaling adapter regulating actin dynamics, is a novel partner of VE-cadherin and is able to modulate YAP activity. By biochemical and imaging approaches, we demonstrate that EPS8 associates with the VE-cadherin complex of remodeling junctions promoting YAP translocation to the nucleus and transcriptional activation. Conversely, in stabilized junctions, 14-3-3-YAP associates with the VE-cadherin complex, whereas Eps8 is excluded. Junctional association of YAP inhibits nuclear translocation and inactivates its transcriptional activity both in vitro and in vivo in Eps8-null mice. The absence of Eps8 also increases vascular permeability in vivo, but ...

Endothelial Signaling in Development and Disease, 2015

Cell-to-cell junctions not only support the crucial function of mutual adhesion among the cells o... more Cell-to-cell junctions not only support the crucial function of mutual adhesion among the cells of the endothelial layer but they also harmonize the signaling and transcription program of each individual cell to its adhesive interactions with neighboring cells. Such coordination is achieved through association with cell-to-cell junctions of multiprotein complexes that can start specific signaling programs, depending on the state of cell-to-cell junctions, and that can also modulate the organization of cell-to-cell junctions themselves. Such reciprocity between adhesion and signaling is crucial for the physiological activity of the endothelium.

Journal of Biology, 2010

The title of this minireview is inspired by the work of the Japanese artist Yayoi Kusama, who pai... more The title of this minireview is inspired by the work of the Japanese artist Yayoi Kusama, who paints wonderful networks as one of her favorite subjects. As an artist, she can evoke images and concepts that are sometimes beyond her own knowledge: in this case her idea of a continuous network well suits a model of intercellular cytoskeletal linking suggested by a recent paper published in BMC Biology by Millan et al. [1]. Working with cultured human umbilical cord vein endothelial cells they find that actin-based stress fibers in adjacent endothelial cells in confluent culture can become linked through adherens junctions. This organization could, in theory, enable a communication network extending throughout the endothelium, as well as maintaining structural coherence and increasing resistance to stress. This capacity could be crucial to the function and adaptability of the endothelium, which is continuously exposed to changes in blood flow, whether in normal physiologic situations, or during inflammation or angiogenesis. This is a novel extension of a concept first used for epithelial sheets [2] to endothelial monolayers. Local regulation of actin by adherens junctions in endothelial cells At early phases of junction formation, actin filaments organize perpendicularly to the membrane through the local accumulation of actin-nucleating complexes [4]. Further stages of junction maturation are accompanied by the development of actin fibers parallel to the mem brane to form a peripheral actin rim ([5] and references therein).

Invasion & metastasis, 1987

Blood platelets have been suggested to play an important role in modulating the development of ex... more Blood platelets have been suggested to play an important role in modulating the development of experimental metastases. Tumour cells can induce platelet aggregation in vitro and a number of mechanisms have been proposed to explain the in vivo and in vitro observations. In the present study, we used tumour cells cloned from B16 melanoma and mouse mammary tumour virus (MMTV) carcinoma polyclonal populations to check whether tumour cells with low- and high-metastatic behaviour in vivo had different quantitative and qualitative platelet-aggregating activity in vitro. We found no significant quantitative difference between platelet aggregation induced by the low- and the high-metastatic clones. Indeed both the high and the low metastatic B16 melanoma clones poorly aggregated platelets, while both the high and low metastatic MMTV carcinoma clones efficiently aggregated platelets. Both the B16 melanoma and the MMTV carcinoma parental cell lines, which can be classed as intermediate metasta...

Disease models & mechanisms

Intracranial hemorrhage (ICH) is a particularly severe form of stroke whose etiology remains poor... more Intracranial hemorrhage (ICH) is a particularly severe form of stroke whose etiology remains poorly understood, with a highly variable appearance and onset of the disease (Felbor et al., 2006; Frizzell, 2005; Lucas et al., 2003). In humans, mutations in any one of three CCM genes causes an autosomal dominant genetic ICH disorder characterized by cerebral cavernous malformations (CCM). Recent evidence highlighting multiple interactions between the three CCM gene products and other proteins regulating endothelial junctional integrity suggests that minor deficits in these other proteins could potentially predispose to, or help to initiate, CCM, and that combinations of otherwise silent genetic deficits in both the CCM and interacting proteins might explain some of the variability in penetrance and expressivity of human ICH disorders. Here, we test this idea by combined knockdown of CCM pathway genes in zebrafish. Reducing the function of rap1b, which encodes a Ras GTPase effector prote...

Adhesion Protein Protocols

... 27. Ausubel, FM, Brent, R., Kingston, RE, Moore, DD, Seidman, JG, Smith, JA, and Struhl, K. (... more ... 27. Ausubel, FM, Brent, R., Kingston, RE, Moore, DD, Seidman, JG, Smith, JA, and Struhl, K. (1993) Current Protocols in Molecular Biology. Greene Pub-lishing and John Wiley, New York. ... 93, 20562065. 32. Coomber, BL and Gotlieb, AI (1990) In vitro endothelial wound repair. ...

Thrombosis Research, 2007

Cell to cell junctions direct endothelial responses both in quiescent and angiogenic vessels. End... more Cell to cell junctions direct endothelial responses both in quiescent and angiogenic vessels. Endothelial cells express both tight and adherens junctions. Although different in their specific molecular composition, these junctional complexes present a relatively similar structural and functional arrangement. Transmembrane adhesive proteins that bind homophilically identical molecules on adjacent cells represent the core component in both types of junctions. This intercellular recognition starts a sequence of signaling events. Signal transmission is mediated through the interaction with cytoplasmic and transmembrane partners. Adherens junctions are ubiquitous along the vascular tree. In these structures VE-cadherin and its intracellular partners mediate adhesion. In vitro and in vivo data show that VE-cadherin is required for endothelial integrity in quiescent vessels and for the correct organization of new vessels. VE-cadherin regulates endothelial functions through different mechanisms which include: (i) direct activation of signaling molecules such as PI3kinase and Rac, to sustain survival and organization of the actin cytoskeleton; (ii) regulation of gene transcription, possibly modulating the nuclear level of transcription co-factors such as beta-catenin and p120; (iii) formation of complexes with growth factor receptors, such as the type 2 receptor of VEGF (VEGFR-2) and modulation of their signaling properties.

Thrombosis and Haemostasis, 2005

SummaryThe pathogenesis of vascular tumors such as angiosarcomas is poorly understood. Cadherin e... more SummaryThe pathogenesis of vascular tumors such as angiosarcomas is poorly understood. Cadherin expression inversely correlates with tumor malignancy and the endothelial specific VE-cadherin is low or absent in angiosarcomas, suggesting an inhibitory role for this protein in tumor progression. In this paper we report that Pmy T VE-cadherin null (VEC null) endothelial cells form larger vascular tumors in nude mice when injected subcutaneously as compared to isogenic VE-cadherin positive (VEC pos) cells. This effect requires the association of β-catenin to VE-cadherin, since a VE-cadherin mutant lacking the domain responsible for β-catenin binding (Δβcat) cannot rescue the phenotype. In VEC null cells β-catenin is phosphorylated and partly degraded. N-cadherin is increased and detected at junctions. VEC null cells also present an altered fibrinolytic activity with increases in tPA, uPA, uPAR and a strong reduction in PAI-1, which may be correlated to the high incidence of abrupt hemor...

Journal of Cell Biology, 1991

Thrombin, in addition to its central role in hemostasis, possesses diverse cellular bioregulatory... more Thrombin, in addition to its central role in hemostasis, possesses diverse cellular bioregulatory functions implicated in wound healing, inflammation, and atherosclerosis. In the present study we demonstrate that thrombin molecules modified either at the procoagulant or catalytic sites induce endothelial cell (EC) adhesion, spreading, and cytoskeletal reorganization. The most potent adhesive thrombin analogue (NO2-alpha-thrombin) was obtained by nitration of tyrosine residues. The cell adhesion promoting activity of NO2-alpha-thrombin was blocked upon the formation of thrombin-antithrombin III (ATIII) complexes and by antiprothrombin antibodies, but was unaffected by hirudin. Arg-Gly-Asp-containing peptides, fully inhibited EC adhesion to NO2-alpha-thrombin, while synthetic peptides corresponding to thrombin "Loop B" mitogenic site and the thrombin-derived chemotactic fragment "CB67-129", were uneffective. Immunofluorescence studies indicated that EC adhesion to ...

Journal of Cell Biology, 2003

Confluent endothelial cells respond poorly to the proliferative signals of VEGF. Comparing isogen... more Confluent endothelial cells respond poorly to the proliferative signals of VEGF. Comparing isogenic endothelial cells differing for vascular endothelial cadherin (VE-cadherin) expression only, we found that the presence of this protein attenuates VEGF-induced VEGF receptor (VEGFR) 2 phosphorylation in tyrosine, p44/p42 MAP kinase phosphorylation, and cell proliferation. VE-cadherin truncated in β-catenin but not p120 binding domain is unable to associate with VEGFR-2 and to induce its inactivation. β-Catenin–null endothelial cells are not contact inhibited by VE-cadherin and are still responsive to VEGF, indicating that this protein is required to restrain growth factor signaling. A dominant-negative mutant of high cell density–enhanced PTP 1 (DEP-1)//CD148 as well as reduction of its expression by RNA interference partially restore VEGFR-2 phosphorylation and MAP kinase activation. Overall the data indicate that VE-cadherin–β-catenin complex participates in contact inhibition of VE...

Proceedings of the National Academy of Sciences, 1999

In the present paper, we characterize an antibody, mAb BV13, directed to mouse vascular endotheli... more In the present paper, we characterize an antibody, mAb BV13, directed to mouse vascular endothelial (VE)-cadherin, a major adhesive protein of interendothelial adherens junctions. When added to cultured endothelial cells, BV13 induces a redistribution of VE-cadherin from intercellular junctions. VE-cadherin redistribution did not change the localization of platelet endothelial cell adhesion molecule or tight junction markers such as zonula occludens 1, cingulin, and junctional adhesion molecule. Intravenous administration of mAb BV13 induced a concentration- and time-dependent increase in vascular permeability in heart and lungs. By electron microscopy, interstitial edema and accumulation of mixed types of inflammatory cells in heart and lungs were observed. Injection of (rhodamine-labeled) Ricinus communis I lectin showed focal spots of exposed basement membrane in the alveolar capillaries and in some larger pulmonary vessels. These data indicate that VE-cadherin is required for va...

Nature Communications, 2012

Endothelial adherens junctions maintain vascular integrity. Arteries and veins differ in their pe... more Endothelial adherens junctions maintain vascular integrity. Arteries and veins differ in their permeability but whether organization and strength of their adherens junctions vary has not been demonstrated in vivo. Here we report that vascular endothelial cadherin, an endothelial specific adhesion protein located at adherens junctions, is phosphorylated in Y658 and Y685 in vivo in veins but not in arteries under resting conditions. This difference is due to shear stress-induced junctional Src activation in veins. Phosphorylated vascular endothelial-cadherin is internalized and ubiquitinated in response to permeability-increasing agents such as bradykinin and histamine. Inhibition of Src blocks vascular endothelial cadherin phosphorylation and bradykinin-induced permeability. Point mutation of Y658F and Y685F prevents vascular endothelial cadherin internalization, ubiquitination and an increase in permeability by bradykinin in vitro. Thus, phosphorylation of vascular endothelial cadherin contributes to a dynamic state of adherens junctions, but is not sufficient to increase vascular permeability in the absence of inflammatory agents.

International Journal of Cancer, 1987

Since the highly metastatic variant M4 of the mFS6 fibrosarcoma has the peculiar feature of gener... more Since the highly metastatic variant M4 of the mFS6 fibrosarcoma has the peculiar feature of generating larger amounts of immunoreactive thromboxane 82 (TxBZ) than the nonmetastatic variant (M9). we used the thromboxane synthase inhibitor dazmegrel (UK-38,485) in an effort to influence its metastatic potential. TxB2 formation by tumor cells freshly harvested from the primary tumor could be completely inhibited by drug addition in vitro. TxB2 generation was inhibited with a dose-response curve, 2 FM being the lowest dazmegrel concentration giving 100% inhibition. Chronic treatment of tumor-bearing mice with dazmegrel (I50 mgikg b.w. twice daily by gavage) from the day of tumor-cell implantation until killing of the animals caused a more than 10-fold reduction in serum TxB2 formation; TxB2 generation by tumor cells was also significantly depressed. This treatment, however, did not significantly modify either primary tumor weight or metastasis formation. Our data suggest that selective inhibition of thromboxane generation in either blood or tumor cells does not prevent spontaneous metastasis formation in the murine model studied. fellow of the Associazione Italiana per la Ricerca contro il Cancro. Dr. C. Cerletti gave valuable advice for radioimmunoassay studies. Mrs. J. Baggott, Mrs. I. Garimoldi, Mr. V. and Mr. F. de Ceglie helped to prepare the manuscript. Prof. C. Patron0 (Catholic University, Rome, Italy) generously provided the anti-TxB2 and anti-6-Keto-PGFla antisera.

Experimental Cell Research, 1987

Cell shape is involved in a variety of cellular activities including proliferation, adhesion, mig... more Cell shape is involved in a variety of cellular activities including proliferation, adhesion, migration, and transformation. Agents known to promote differentiation, such as retinoic acid, butyrate, and dibutyryl cyclic AMP, induce marked alterations in cell shape which are often accompanied by changes in cell functions. In this paper we study the effects of the differentiating polar solvent dimethyl sulfoxide (DMSO) on cytoskeleton, adhesion, and growth properties of cultured mouse B16 melanoma cells. DMSO induced a progressive reorganization of the cytoskeleton which was fully developed in 4 days of continuous exposure to the agent. DMSO-treated cells developed thick and regularly oriented microfilament bundles of the stress fiber type ending at vinculin-rich areas of focal contact between the ventral membrane and the substratum (interference reflection microscopydark adhesion plaques). Such a rearrangement of the cytoskeleton resulted in increased adhesion to the substratum and inhibition of cell growth in comparison to control untreated cells. Cells which became highly flattened and tightly adherent after exposure to DMSO for 4 days progressively reverted their phenotype to that of control untreated cells within 3 days of DMSO withdrawal. Namely, they lost stress fibers and adhesion plaques, became rounded and less adherent, and increased their growth rate. These results indicate that DMSO can change the transformed appearance of B16 mouse melanoma cells to a phenotype which is typical of a variety of nontransformed cells in culture.