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See detailRhoGDI alpha-dependent balance between RhoA and RhoC is a key regulator of cancer cell tumorigenesis
Ho, Thi Thanh Giang ULg; Stultiens, Audrey; Dubail, Johanne ULg et al

in Molecular Biology of the Cell (2011), 22(17), 3263-75

RhoGTPases are key signaling molecules regulating main cellular functions such as migration, proliferation, survival, and gene expression through interactions with various effectors. Within the RhoA ... [more ▼]

RhoGTPases are key signaling molecules regulating main cellular functions such as migration, proliferation, survival, and gene expression through interactions with various effectors. Within the RhoA-related subclass, RhoA and RhoC contribute to several steps of tumor growth, and the regulation of their expression affects cancer progression. Our aim is to investigate their respective contributions to the acquisition of an invasive phenotype by using models of reduced or forced expression. The silencing of RhoC, but not of RhoA, increased the expression of genes encoding tumor suppressors, such as nonsteroidal anti-inflammatory drug-activated gene 1 (NAG-1), and decreased migration and the anchorage-independent growth in vitro. In vivo, RhoC small interfering RNA (siRhoC) impaired tumor growth. Of interest, the simultaneous knockdown of RhoC and NAG-1 repressed most of the siRhoC-related effects, demonstrating the central role of NAG-1. In addition of being induced by RhoC silencing, NAG-1 was also largely up-regulated in cells overexpressing RhoA. The silencing of RhoGDP dissociation inhibitor alpha (RhoGDIalpha) and the overexpression of a RhoA mutant unable to bind RhoGDIalpha suggested that the effect of RhoC silencing is indirect and results from the up-regulation of the RhoA level through competition for RhoGDIalpha. This study demonstrates the dynamic balance inside the RhoGTPase network and illustrates its biological relevance in cancer progression. [less ▲]

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See detailADAMTS-2 functions as anti-angiogenic and anti-tumoral molecule independently of its catalytic activity.
Dubail, Johanne ULg; Kesteloot, F.; Deroanne, Christophe ULg et al

in Cellular & Molecular Life Sciences (2010)

ADAMTS-2 is a metalloproteinase that plays a key role in the processing of fibrillar procollagen precursors into mature collagen molecules by excising the amino-propeptide. We demonstrate that recombinant ... [more ▼]

ADAMTS-2 is a metalloproteinase that plays a key role in the processing of fibrillar procollagen precursors into mature collagen molecules by excising the amino-propeptide. We demonstrate that recombinant ADAMTS-2 is also able to reduce proliferation of endothelial cells, and to induce their retraction and detachment from the substrate resulting in apoptosis. Dephosphorylation of Erk1/2 and MLC largely precedes the ADAMTS-2 induced morphological alterations. In 3-D culture models, ADAMTS-2 strongly reduced branching of capillary-like structures formed by endothelial cells and their long-term maintenance and inhibited vessels formation in embryoid bodies (EB). Growth and vascularization of tumors formed in nude mice by HEK 293-EBNA cells expressing ADAMTS-2 were drastically reduced. A similar anti-tumoral activity was observed when using cells expressing recombinant deleted forms of ADAMTS-2, including catalytically inactive enzyme. Nucleolin, a nuclear protein also found to be associated with the cell membrane, was identified as a potential receptor mediating the antiangiogenic properties of ADAMTS-2. [less ▲]

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See detailNewly identified biologically active and proteolysis-resistant VEGF-A isoform VEGF111 is induced by genotoxic agents
Mineur, Pierre ULg; Colige, Alain ULg; Deroanne, Christophe ULg et al

in Journal of Cell Biology (2007), 179(6), 1261-1273

Ultraviolet B and genotoxic drugs induce the expression of a vascular endothelial growth factor A (VEGF-A) splice variant (VEGF111) encoded by exons 1-4 and 8 in many cultured cells. Although not detected ... [more ▼]

Ultraviolet B and genotoxic drugs induce the expression of a vascular endothelial growth factor A (VEGF-A) splice variant (VEGF111) encoded by exons 1-4 and 8 in many cultured cells. Although not detected in a series of normal human and mouse tissue, VEGF111 expression is induced in MCF-7 xenografts in nude mice upon treatment by camptothecin. The skipping of exons that contain proteolytic cleavage sites and extracellular matrix-binding domains makes VEGF111 diffusible and resistant to proteolysis. Recombinant VEGF111 activates VEGF receptor 2 (VEGF-R2) and extracellularly regulated kinase 1/2 in human umbilical vascular endothelial cells and porcine aortic endothelial cells expressing VEGF-R2. The mitogenic and chemotactic activity and VEGF111's ability to promote vascular network formation during embyonic stem cell differentiation are similar to those of VEGF121 and 165. Tumors in nude mice formed by HEK293 cells expressing VEGF111 develop a more widespread network of numerous small vessels in the peritumoral tissue than those expressing other isoforms. Its potent angiogenic activity and remarkable resistance to proteolysis makes VEGF111 a potential adverse factor during chemotherapy but a beneficial therapeutic tool for ischemic diseases. [less ▲]

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See detailDomains and maturation processes that regulate the activity of ADAMTS-2, a metalloproteinase cleaving the aminopropeptide of fibrillar procollagens types I-III and V
Colige, Alain ULg; Ruggiero, Florence; Vandenberghe, Isabel et al

in Journal of Biological Chemistry (2005), 280(41), 34397-34408

Processing of fibrillar collagens is required to generate collagen monomers able to self-assemble into elongated and cylindrical collagen fibrils. ADAMTS-2 belongs to the "A disintegrin and ... [more ▼]

Processing of fibrillar collagens is required to generate collagen monomers able to self-assemble into elongated and cylindrical collagen fibrils. ADAMTS-2 belongs to the "A disintegrin and metalloproteinase with thrombospondin type 1 motifs" (ADAMTS) family. It is responsible for most of the processing of the aminopropeptide of type I procollagen in the skin, and it also cleaves type II and type III procollagens. ADAMTS are complex secreted enzymes that are implicated in various physiological and pathological processes. Despite accumulating evidence indicating that their activity is regulated by ancillary domains, additional information is required for a better understanding of the specific function of each domain. We have generated 17 different recombinant forms of bovine ADAMTS-2 and characterized their processing, activity, and cleavage specificity. The results indicated the following: (i) activation of the ADAMTS-2 zymogen involves several cleavages, by proprotein convertases and C-terminal processing, and generates at least seven distinct processed forms; (ii) the C-terminal domain negatively regulates enzyme activity, whereas two thrombospondin type 1 repeats are enhancer regulators; (iii) the 104-kDa form displays the highest aminoprocollagen peptidase activity on procollagen type I; (iv) ADAMTS-2 processes the aminopropeptide of alpha1 type V procollagen homotrimer at the end of the variable domain; and (v) the cleaved sequence (PA) is different from the previously described sites ((P/A)Q) for ADAMTS-2, redefining its cleavage specificity. This finding and the existence of multiple processed forms of ADAMTS-2 strongly suggest that ADAMTS-2 may be involved in function(s) other than processing of fibrillar procollagen types I-III. [less ▲]

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See detailADAMTS-2, a metalloproteinase containing a disintegrin domain and thrombospondin type I repeats, a new regulator of angiogenesis
Dubail, Johanne ULg; Kesteloot, Frédéric ULg; Motte, Patrick ULg et al

in Journal of Vascular Research (2005), 42(Suppl. 2), 76

Enzymes of the ADAMTS family are closely related to MMPs and ADAMs. They further contain specific domains, such as the “ThromboSpondin type I” (TSP1) repeats able to strongly repress angiogenesis. The ... [more ▼]

Enzymes of the ADAMTS family are closely related to MMPs and ADAMs. They further contain specific domains, such as the “ThromboSpondin type I” (TSP1) repeats able to strongly repress angiogenesis. The primary function of ADAMTS-2 is to process procollagen type I, II, III and V into mature molecules by excising the amino-propeptide. We further hypothesized that it could modulate angiogenesis through its TSP1 repeats. Recombinant ADAMTS-2 induced morphological changes in HUVEC and HMEC cultured on gelatin, collagen and fibronectin. It also significantly reduced their proliferation, attachment and spreading. Similar effects were observed when using inactive ADAMTS-2 mutated at the Zn++-binding catalytic site. ADAMTS-2 did not alter the initial steps of formation of capillary-like structures by HUVEC in vitro. However, these structures appeared more rapidly disrupted in presence of ADAMTS-2 than in control conditions. Immunostaining with monoclonal antibodies against ADAMTS-2 indicate that it is tightly immobilized at the endothelial cell surface by an heparin-sensitive binding. With the aim to identify mechanism(s)leading to the modulation of angiogenesis by ADAMTS-2, we investigated various signalling pathways critical for EC. Phosphorylation status of FAK was not altered by ADAMTS-2 while a downregulation of phosphorylation of p42/44 MAPK was observed. Our data suggest that ADAMTS-2 reduces angiogenesis by regulating endothelial cell adhesion and proliferation, and by alteration of the stability of the capillary-like structures. These effects do not seem to be mediated by an integrin-dependent signaling pathway. Choroidal neovascularization induced in TS2+/+ or TS2-/- mice by LASER burns was used as in vivo model. Several genes involved in the healing and angiogenesis processes (fibrillar collagens, VEGF, TGF, CTGF, …) were not differently regulated in TS2+/+ and TS2-/- mice 5 days after the LASER impact. Wound capillaries visualized by confocal microscopy after FITC-conjugated dextran injection, were significantly increased (p<0,05) in TS2-/- mice suggesting an increased angiogenic response in the KO animals. The results obtained in in vivo and in vitro models indicate that ADAMTS-2 is involved in the control of angiogenesis. Additional investigations are being performed to determine which domain(s) of the molecule is (are) antiangiogenic and to identify the mechanism(s) underlying this regulatory function. [less ▲]

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See detailEffect of ADAMTS-2, a metalloproteinase containing a disintegrin domain and thrombospondin type I repeats, during angiogenesis in vitro and in vivo
Dubail, Johanne ULg; Kesteloot, Frédéric ULg; Motte, Patrick ULg et al

in Angiogenesis (2004), 7(2), 172

Formation of new blood vessels (angiogenesis) is a key step during the development of various pathologies, including cancer. Enzymes of the ADAMTS family are closely related to MMPs and ADAMs. They ... [more ▼]

Formation of new blood vessels (angiogenesis) is a key step during the development of various pathologies, including cancer. Enzymes of the ADAMTS family are closely related to MMPs and ADAMs. They further contain specific domains, such as the ‘‘Thrombospondin type I’’ (TSP1) repeats, that are able to strongly repress angiogenesis, as described for thrombospondin-1 and -2, and for ADAMTS-1 and -8. The primary function of ADAMTS-2 is to process collagen type I, II and III precursors into mature molecules by excising the aminopropeptide. We further hypothesized that it could modulate angiogenesis through its TSP1 repeats. This hypothesis was investigated using different in vitro experimental models of angiogenesis. Recombinant ADAMTS-2 induced morphological changes in human umbilical vein endothelial cells (HUVEC) and human microvessel endothelial cells (HMEC), and significantly reduced their proliferation, attachment and spreading. Similar effects were observed when using inactive ADAMTS-2 mutated at the Zn2+-binding catalytic site. ADAMTS-2 did not alter the initial steps of formation of capillary-like structures by HUVEC in vitro. However, these structures appeared much less stable and were more rapidly disrupted in presence of ADAMTS-2 than in control conditions. ADAMTS-2 was also tested in an ex vivo angiogenesis model using aortic rings from rats and mice, wild type or KO for ADAMTS-2. Outgrowth of capillaries was slightly increased from aortas of ADAMTS-2 KO mice (TS2-/-) as compared to aortas from control animals (TS2+/+), while addition of full size recombinant ADAMTS-2 reduced the formation of capillary structures from rat aortas, suggesting its anti-angiogenic activity. Choroidal neovascularization induced in TS2+/+ or TS2-/- mice by LASER burns was used as in vivo model to confirm the in vitro and ex vivo results. Several genes involved in the healing and angiogenesis processes (fibrillar collagens, VEGF, TGF-beta and CTGF) were not differently regulated in TS2+/+ and TS2-/- mice at 5 days. [less ▲]

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See detailExpression of 25 kDa thiamine triphosphatase in rodent tissues using quantitative PCR and characterization of its mRNA
Lakaye, Bernard ULg; Verlaet, Myriam ULg; Dubail, Johanne ULg et al

in International Journal of Biochemistry & Cell Biology (2004), 36(10), 2032-2041

Thiamine triphosphate (ThTP) is found in most organisms, but its biological role remains unclear. In mammalian tissues, cellular ThTP concentrations remain low, probably because of hydrolysis by a ... [more ▼]

Thiamine triphosphate (ThTP) is found in most organisms, but its biological role remains unclear. In mammalian tissues, cellular ThTP concentrations remain low, probably because of hydrolysis by a specific 25 kDa thiamine triphosphatase (ThTPase). The aim of the present study was to use quantitative PCR, for comparing the 25 kDa ThTPase mRNA expression in various mouse tissues with its enzyme activities. ThTPase mRNA was expressed at only a few copies per cell. The highest amount of mRNA was found in testis, followed by lung and muscle, while the highest enzyme activities were found in liver and kidney. The poor correlation between mRNA levels and enzyme activities might result either from tissue-specific post-transcriptional regulation of mRNA processing and/or translation or from the regulation of enzyme activities by post-translational mechanisms. Purified recombinant human ThTPase was phosphorylated by casein kinase 11, but this phosphorylation did not modify the enzyme activity. However, the characterization of the 3'-untranslated mRNA region revealed a unique, highly conserved, 200-nucleotide sequence that might be involved in translational control. In situ hybridization studies in testis suggest a predominant localization of ThTPase mRNA in poorly differentiated spermatogenic cells. This is the first study demonstrating a cell-specific 25 kDa ThTPase mRNA expression, suggesting that this enzyme might be related to the degree of differentiation or the metabolic state of the cell. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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