References of "Lambert, Charles"
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See detailEstablishment of stable human fibroblast cell lines constitutively expressing active Rho-GTPases.
Servotte, S.; Zhang, Z.; Lambert, Charles ULg et al

in Protoplasma (2006), 229(2-4), 215-20

Small GTP-binding proteins of the Rho family (RhoA, Cdc42, Rac1) regulate the organisation and the turnover of the cell's cytoskeleton and adhesion structures. A significant function of these cellular ... [more ▼]

Small GTP-binding proteins of the Rho family (RhoA, Cdc42, Rac1) regulate the organisation and the turnover of the cell's cytoskeleton and adhesion structures. A significant function of these cellular structures is to translate and counterbalance forces applied to, or generated by, cells in order to maintain homeostasis and control cell movement. We therefore hypothesised that Rho-GTPases are directly involved in cellular gravity perception and may participate in the alterations induced in microgravity. To define an adequate cellular model allowing to investigate this issue, we have established stable cell lines constitutively expressing active forms of either RhoA, Cdc42, or Rac1. The three cell lines differ by morphology and by their ability to form filopodia, lamellipodia, and bundles of actin stress fibers. Overexpression of the active form of either RhoA, Cdc42, or Rac1 is compatible with cell viability and does not affect cell population doubling time. Thus, our series of mutant cells appear well suited to gain further knowledge on the molecular mechanisms of cellular gravity perception. [less ▲]

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See detailEffects of constitutively active GTPases on fibroblast behavior.
Zhang, Z.-G.; Lambert, Charles ULg; Servotte, S. et al

in Cellular and Molecular Life Sciences : CMLS (2006), 63(1), 82-91

The GTP-binding proteins RhoA, Cdc42 and Rac1 regulate the organization and turnover of the cytoskeleton and cell-matrix adhesions, structures bridging cells to their support, and translating forces ... [more ▼]

The GTP-binding proteins RhoA, Cdc42 and Rac1 regulate the organization and turnover of the cytoskeleton and cell-matrix adhesions, structures bridging cells to their support, and translating forces, external or generated within the cell. To investigate the specific requirements of Rho GTPases for biomechanical activities of clonal cell populations, we compared side-by-side stable lines of human fibroblasts expressing constitutively active (CA) RhoA, Cdc42 or Rac1. There was no marked effect of any CA GTPase on cell adhesion to different extracellular matrix proteins. Cell spreading was CA Rho GTPase specific and independent of the extracellular matrix proteins allowing adhesion. Mechanical properties were dramatically restricted by CA RhoA on bi- and in tri-dimensional surroundings, were boosted by CA Rac1 on bi-dimensional surroundings only, and were not or marginally affected by CA Cdc42. In conclusion, the action of Rho GTPases appears to depend on the task cells are performing. [less ▲]

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See detailAcidic extracellular pH induces matrix metalloproteinase-9 expression in mouse metastatic melanoma cells through the phospholipase D-mitogen-activated protein kinase signaling
Kato, Y.; Lambert, Charles ULg; Colige, Alain ULg et al

in Journal of Biological Chemistry (2005), 280(12), 10938-10944

The extracellular pH (pHe) of tumor tissues is often acidic, which can induce the expression of several proteins. We previously showed that production of matrix metalloproteinase-9 (MMP-9) was induced by ... [more ▼]

The extracellular pH (pHe) of tumor tissues is often acidic, which can induce the expression of several proteins. We previously showed that production of matrix metalloproteinase-9 (MMP-9) was induced by culturing cells at acidic pHe (5.4-6.5). Here we have investigated the signal transduction pathway by which acidic pHe induces MMP-9 expression. We found that acidic pHe (5.9) activated phospholipase D (PLD), and inhibition of PLD activity by 1-butanol and Myr-ARF6 suppressed the acidic pHe-induced MMP-9 expression. Exogenous PLD, but not phosphatidylinositol-specific PLC or PLA(2), mimicked MMP-9 induction by acidic pHe. Western blot analysis revealed that acidic pHe increased the steady-state levels of phosphorylated extracellular signal-regulated kinases 1/2 and p38 and that the PLD inhibitors suppressed these increases. Using 5'-deletion mutant constructs of the MMP-9 promoter, we found that the acidic pHe-responsive region was located at nucleotide -670 to -531, a region containing the NF kappa B binding site. A mutation into the NF kappa B binding site reduced, but not completely, the acidic pHe- induced MMP-9 promoter activity, pand NF kappa B activity was induced by acidic pHe. Pharmacological inhibitors specific for mitogen-activated protein kinase kinase 1/2 (PD098059) and p38 (SB203580) attenuated the acidic pHe- induced NF kappa B activity and MMP-9 expression. These data suggest that PLD, mitogen-activated protein kinases (extracellular signal-regulated kinases 1/2 and p38), and NF kappa B mediate the acidic pHe signaling to induce MMP-9 expression. A transcription factor(s) other than NF kappa B may also be involved in the MMP-9 expression. [less ▲]

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See detailMurine bone marrow stromal cells sustain in vivo the survival of hematopoietic stem cells and the granulopoietic differentiation of more mature progenitors.
Hubin, Frederique; Humblet, Chantal ULg; Belaid, Zakia ULg et al

in Stem Cells (2005), 23(10), 1626-33

The study of the human hematopoietic system would be facilitated by availability of a relevant animal model. Because the medullar microenvironment is made of different types of cells, interactions between ... [more ▼]

The study of the human hematopoietic system would be facilitated by availability of a relevant animal model. Because the medullar microenvironment is made of different types of cells, interactions between hematopoietic cells and stromal cells are difficult to analyze in detail. As an approach for establishing an in vivo model to dissect these interactions, we grafted murine bone marrow fibroblastic cells (MS-5 cell line) with hematopoietic cells into the kidney capsule of syngenic mice. To identify the origin of cells present in the graft, we used green fluorescent protein-stable transfected MS-5 cells for the transplantation. To analyze the evolution of stromal cells and identify hematopoietic cells able to develop in these conditions, we performed morphology, histochemistry, and immunohistology on tissue sections at different times after transplantation. When injected alone, MS-5 cells differentiate into adipocytes. When injected with a bone marrow suspension or with isolated CD45+ cells (leukocytes), the stromal cells keep their fibroblastic morphology and their alkaline phosphatase expression and sustain granulopoiesis. When injected with hematopoietic stem cells called c-kit+ Sca-1+ Lin- suspension, clusters of hematopoietic cells are also observed: They do not present any granulopoietic activity and do not belong to B or T population nor to erythroid lineage. They are quiescent, induce bone marrow recovery and survival of lethally irradiated recipients, are able to form macroscopic colonies in the spleen, and are able to form very few colonies in vitro, suggesting that they are hematopoietic stem cells. In conclusion, our results show that reticular fibroblastic stromal cells MS-5 sustain the survival of stem cells and are not able to induce their differentiation. However, they can control differentiation, proliferation, and/or survival of hematopoietic cells engaged in myeloid lineage. [less ▲]

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See detailCdc42 downregulates MMP-1 expression by inhibiting the ERK1/2 pathway.
Deroanne, Christophe ULg; Hamelryckx, Delphine; Ho, Thi Thanh Giang ULg et al

in Journal of Cell Science (2005), 118(Pt 6), 1173-83

The small GTPases of the Rho family are key intermediates in cellular signalling triggered by activated cell-adhesion receptors. In this study, we took advantage of RNA interference (RNAi) using small ... [more ▼]

The small GTPases of the Rho family are key intermediates in cellular signalling triggered by activated cell-adhesion receptors. In this study, we took advantage of RNA interference (RNAi) using small interfering RNAs (siRNAs) to define the roles of the best-characterized members of the RhoGTPase family, RhoA, Rac1 and Cdc42, in the control of MMP-1, MMP-2 and type-I-collagen expression in normal human skin fibroblasts (HSFs). A specific and long-lasting repression, up to 7 days after transfection, of the three GTPases was achieved by transient transfection of specific siRNA. The silencing of Cdc42, but not that of RhoA or Rac1, induced a 15-fold increase in MMP-1 secretion. This upregulation was confirmed at the mRNA level and observed with two different siRNAs targeting Cdc42. Such a regulation was also observed in various human cell lines and was rescued by re-expressing wild-type Cdc42 encoded by a construct bearing silent mutations impeding its recognition by the siRNA. By contrast, MMP-2 and type-I-collagen expression was not affected by the individual silencing of each Rho GTPase. Cytokine protein array, enzyme-linked immunosorbent assays and reverse-transcription PCR measurements revealed that ablation of Cdc42 induced an overexpression of interleukin 8 and MCP-1. Although these cytokines are known to induce the expression of MMP-1, we showed that they were not involved in the Cdc42-mediated upregulation of MMP-1. Silencing of Cdc42 also induced an increased phosphorylation of ERK1/2 and p38 MAP kinase. The use of chemical inhibitors on Cdc42-ablated cells revealed that the upregulation of MMP-1 is dependent on the ERK1/2 pathways, whereas the p38 MAP kinase pathway displayed an inhibitory role. Simultaneous knock-down of two or three Rho GTPases allowed us to demonstrate that the RhoA-ROCK pathway was not involved in this regulation but that the silencing of Rac1 reduced the effect of Cdc42 suppression. These data suggest that, in vivo, when cell/extracellular-matrix interactions via integrins induce cytoskeleton organization, MMP-1 expression is maintained at a low level by Cdc42 via a repression of the Rac1 and ERK1/2 pathways. Therefore, Cdc42 contributes to ECM homeostasis and connective tissue integrity. [less ▲]

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See detailRole of the RhoGTPases in the cellular receptivity and reactivity to mechanical signals including microgravity
Nusgens, Betty ULg; Chometon, G.; Guignandon, Alain et al

in Journal of Gravitational Physiology : A Journal of the International Society for Gravitational Physiology (2005), 12(1), 269-270

The small G proteins of the Rho Family (RhoGTPases) are key operators in the signaling arising from extracellular matrix through integrin receptors and from membrane receptors for soluble ligands. FLight ... [more ▼]

The small G proteins of the Rho Family (RhoGTPases) are key operators in the signaling arising from extracellular matrix through integrin receptors and from membrane receptors for soluble ligands. FLight data show that microgravity affects cell architecture and gene expression leading us to assume that the signaling pathways(s) involving the RhoGTPAses might disturbed in a weightlessness environment. TO test this hypothesis in microgravityu, we created genetically engineered human fibroblasts that will be used in Biolab on the ISS. [less ▲]

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See detailMicrogravity-induced matrix remodelling is linked to reduction in tension of human dermal fibroblasts
Guignandon, A.; Lambert, Charles ULg; Réga, Georgette et al

in Journal of Gravitational Physiology : A Journal of the International Society for Gravitational Physiology (2005), 12(1),

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See detailRGDS and DGEA-induced [Ca2+]i signalling in human dermal fibroblasts.
Mineur, Pierre ULg; Guignandon, A.; Lambert, Charles ULg et al

in Biochimica et Biophysica Acta (2005), 1746(1), 28-37

A pulse of short peptides, RGDS and DGEA in the millimolar range, immediately elicits in normal human fibroblasts a transient increase of intracellular Ca2+ ([Ca2+]i). In the present study, we show that ... [more ▼]

A pulse of short peptides, RGDS and DGEA in the millimolar range, immediately elicits in normal human fibroblasts a transient increase of intracellular Ca2+ ([Ca2+]i). In the present study, we show that this [Ca2+]i occurs in an increasing number of cells as a function of peptides concentration. It is specific of each peptide and inhibited at saturating concentration of the peptide in the culture medium. The [Ca2+]i transient depends on signalling pathways slightly different for DGEA and RGDS involving tyrosine kinase(s) and phosphatase(s), phospholipase C, production of inositol-trisphosphate and release of Ca2+ from the cellular stores. GFOGER, the classical collagen binding peptide of alpha1- alpha2- and alpha11-beta1 integrins, in triple helical or denatured form, does not produce any Ca2+ signal. The [Ca2+]i signalling induced by RGDS and DGEA is inhibited by antibodies against beta1 integrin subunit while that mediated by RGDS is also inhibited by antibodies against the alpha3 integrin. Delay in the acquisition of responsiveness is observed during cell adhesion and spreading on a coat of fibronectin for RGDS or collagen for DGEA or on a coat of the specific integrin-inhibiting antibodies but not by seeding cells on GFOGER or laminin-5. This delay is suppressed specifically by collagenase acting on the collagen coat or trypsin on the fibronectin coat. Our results suggest that free integrins and associated focal complexes generate a Ca2+ signal upon recognition of DGEA and RGDS by different cellular pathways. [less ▲]

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See detailCell survival and preservation of siRNA-mediated protein knock-down upon serum-free cryopreservation (-80 degrees C).
Lambert, Charles ULg; Deroanne, Christophe ULg; Servotte, Sandrine et al

in Gravitational and Space Biology Bulletin (2005), 18(2), 103-4

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See detailGradient of proteolytic enzymes, their inhibitors and matrix proteins expression in a ruptured abdominal aortic aneurysm
Defawe, O. D.; Colige, Alain ULg; Lambert, Charles ULg et al

in European Journal of Clinical Investigation (2004), 34(7), 513-514

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See detailChanges in matrix gene and protein expressions after single or repeated exposure to one minimal erythemal dose of solar-simulated radiation in human skin in vivo
Seite, S.; Colige, Alain ULg; Deroanne, Christophe ULg et al

in Photochemistry and Photobiology (2004), 79(3), 265-271

Damage to the skin extracellular matrix (ECM) is the hallmark of long-term exposure to solar UV radiation. The aim of our study was to investigate the changes induced in unexposed human skin in vivo after ... [more ▼]

Damage to the skin extracellular matrix (ECM) is the hallmark of long-term exposure to solar UV radiation. The aim of our study was to investigate the changes induced in unexposed human skin in vivo after single or repeated (five times a week for 6 weeks) exposure to I minimal erythemal dose (MED) of UV solar-simulated radiation. Morphological and biochemical analyses were used to evaluate the structural ECM components and the balance between the degrading enzymes and their physiologic inhibitors. A three-fold increase in matrix metalloproteinase 2 messenger RNA (mRNA) (P < 0.02, unexposed versus exposed) was observed after both single and repeated exposures. Fibrillin 1 mRNA level was increased by chronic exposure (P < 0.02) and unaltered by a single MED. On the contrary, a single MED significantly enhanced mRNA levels of interleukin-la (IL-1alpha), IL-1beta (P < 0.02) and plasminogen activator inhibitor-1 (P < 0.05). Immunohistochemistry demonstrated a significant decrease in Type-I procollagen localized just below the dermal-epidermal junction in both types of exposed sites. At the same location, the immunodetected tenascin was significantly enhanced, whereas a slight increase in Type-III procollagen deposits was also observed in chronically exposed areas. Although we were unable to observe any change in elastic fibers in chronically exposed buttock skin, a significant increase in lysozyme and alpha-1 antitrypsin deposits on these fibers was observed. These results demonstrate the existence of a differential regulation, after chronic exposure compared with an acute one, of some ECM components and inflammatory mediators. [less ▲]

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See detailDesign and evaluation of new hydrogels for biomaterial purposes
Grandfils, Christian ULg; Barakat, I; Fairon, N et al

Conference (2003, October 23)

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See detailDesign and evaluation of new reinforced hydrogel membranes for biomaterial purposes
Fairon, N; Grandfils, Christian ULg; Barakat, I et al

Poster (2003, October 23)

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See detailTIMP-2 and PAI-1 mRNA levels are lower in aneurysmal as compared to athero-occlusive abdominal aortas.
Defawe, Olivier D; Colige, Alain ULg; Lambert, Charles ULg et al

in Cardiovascular Research (2003), 60(1), 205-13

OBJECTIVE: Significant alterations of the vascular wall occurs in abdominal aortic aneurysm (AAA) and atherosclerotic occlusive disease (AOD) that ultimately may lead to either vascular rupture or ... [more ▼]

OBJECTIVE: Significant alterations of the vascular wall occurs in abdominal aortic aneurysm (AAA) and atherosclerotic occlusive disease (AOD) that ultimately may lead to either vascular rupture or obstruction. These modifications have been ascribed to one or a group of proteases, their inhibitors or to the matrix macromolecules involved in the repair process without considering the extent of the observed variations. METHODS: The mRNA steady-state level of a large spectrum of proteolytic enzymes (matrix metalloproteinases: MMP-1, -2, -3, -8, -9, -11, -12, -13, -14; urokinase plasminogen activator: u-PA), their physiological inhibitors (tissue inhibitors of MMPs: TIMP-1, -2, -3; plasminogen activator inhibitor: PAI-1) and that of structural matrix proteins (collagens type I and III, decorin, elastin, fibrillins 1 and 2) was determined by RT-PCR made quantitative by using a synthetic RNA as internal standard in each reaction mixture. The profile of expression was evaluated in AAA (n=7) and AOD (n=5) and compared to non-diseased abdominal (CAA, n=7) and thoracic aorta (CTA, n=5). RESULTS: The MMPs -8, -9, -12 and -13 mostly associated with inflammatory cells were not or barely detected in CAA and CTA while they were largely and similarly expressed in AAA and AOD. Expression of protease inhibitors or structural proteins were only slightly increased in both pathological conditions with the exception of elastin which was reduced. The main significant difference between AAA and AOD was a lower expression of TIMP-2 and PAI-1 in the aneurysmal lesions. CONCLUSIONS: The remodeling of the aortic wall in AAA and AOD involves gene activation of a large and similar spectrum of proteolytic enzymes while the expression of two physiological inhibitors, TIMP-2 and PAI-1, is significantly lower in AAA compared to AOD. The repair process in the aneurysmal disease seems similar to that of the occlusive disease. [less ▲]

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See detailStimulation of matrix metalloproteinase-9 expression in human fibrosarcoma cells by synthetic matrix metalloproteinase inhibitors.
Maquoi, Erik ULg; Munaut, Carine ULg; Colige, Alain ULg et al

in Experimental Cell Research (2002), 275(1), 110-21

Enhanced expression and activation of matrix metalloproteinase-2 (MMP-2) and MMP-9 have been associated with tumor progression, invasion, and metastasis. The use of synthetic MMP inhibitors to block the ... [more ▼]

Enhanced expression and activation of matrix metalloproteinase-2 (MMP-2) and MMP-9 have been associated with tumor progression, invasion, and metastasis. The use of synthetic MMP inhibitors to block the proteolytic activity of these enzymes recently emerged as a potential therapeutic tool to treat cancer. In this study, we report that GI129471, a synthetic broad-spectrum MMP inhibitor, efficiently reduced the in vitro invasiveness of HT1080 cells through type IV collagen, a major component of basement membranes. This reduced invasion was paralleled by a complete inhibition of pro-MMP-2 activation; however, GI129471 strongly increased the amount of secreted pro-MMP-9, which could be subsequently activated through a plasminogen-dependent mechanism. Quantitative RT-PCR and northern blot analysis revealed that GI129471 specifically increased the MMP-9 mRNA steady-state level. Moreover, transient transfection of HT1080 cells with beta-galactosidase reporter vectors containing different lengths of the 5'-flanking region of the MMP-9 gene revealed an upregulation of the transcriptional activity of the corresponding promoter. Well-known modulators of MMP-9 expression such as Il-1beta and TNF-alpha were not involved in this upregulation. These findings emphasize the complexity of the regulation of MMP expression and the requirement for a detailed characterization of the potential adverse side effects associated with the use of broad-spectrum MMPIs. [less ▲]

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See detailCloning and characterization of ADAMTS-14, a novel ADAMTS displaying high homology with ADAMTS-2 and ADAMTS-3.
Colige, Alain ULg; Vandenberghe, Isabel; Thiry, Marc ULg et al

in Journal of Biological Chemistry (2002), 277(8), 5756-66

The processing of amino- and carboxyl-propeptides of fibrillar collagens is required to generate collagen monomers that correctly assemble into fibrils. Mutations in the ADAMTS2 gene, the ... [more ▼]

The processing of amino- and carboxyl-propeptides of fibrillar collagens is required to generate collagen monomers that correctly assemble into fibrils. Mutations in the ADAMTS2 gene, the aminopropeptidase of procollagen I and II, result in the accumulation of non-fully processed type I procollagen, causing human Ehlers-Danlos syndrome type VIIC and animal dermatosparaxis. In this study, we show that the aminopropeptide of type I procollagen can be cleaved in vivo in absence of ADAMTS-2 activity and that this processing is performed at the cleavage site for ADAMTS-2. In an attempt to identify the enzyme responsible for this alternative aminoprocollagen peptidase activity, we have cloned the cDNA and determined the primary structure of human and mouse ADAMTS-14, a novel ADAMTS displaying striking homologies with ADAMTS-2 and -3. The structure of the human gene, which maps to 10q21.3, and the mechanisms of generation of the various transcripts are described. The existence of two sites of initiation of transcription, in two different promoter contexts, suggests that transcripts resulting from these two sites can be differently regulated. The tissue distribution of ADAMTS-14, the regulation of the gene expression by various cytokines and the activity of the recombinant enzyme are evaluated. The potential function of ADAMTS-14 as a physiological aminoprocollagen peptidase in vivo is discussed. [less ▲]

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See detailTopically applied vitamin C enhances the mRNA level of collagens I and III, their processing enzymes and tissue inhibitor of matrix metalloproteinase 1 in the human dermis.
Nusgens, Betty ULg; Humbert, Philippe; Rougier, André et al

in Journal of Investigative Dermatology (2001), 116(6), 853-9

Ascorbic acid (vitamin C) is a cofactor required for the function of several hydroxylases and monooxygenases. It is not synthesized in humans and some other animal species and has to be provided by diet ... [more ▼]

Ascorbic acid (vitamin C) is a cofactor required for the function of several hydroxylases and monooxygenases. It is not synthesized in humans and some other animal species and has to be provided by diet or pharmacologic means. Its absence is responsible for scurvy, a condition related in its initial phases to a defective synthesis of collagen by the reduced function of prolylhydroxylase and production of collagen polypeptides lacking hydroxyproline, therefore, they are unable to assemble into stable triple-helical collagen molecules. In fibroblast cultures, vitamin C also stimulates collagen production by increasing the steady-state level of mRNA of collagen types I and III through enhanced transcription and prolonged half-life of the transcripts. The aim of the experimental work has been to evaluate the effect on dermal cells of a preparation of vitamin C topically applied on one side vs placebo on the other side of the dorsal face of the upper forearm of postmenopausal women. Biopsies were collected on both sides and the level of mRNA measured by non competitive reverse transcription-polymerase chain reaction made quantitative by the simultaneous transcription and amplification of synthetic RNA used as internal standards. The mRNA of collagen type I and type III were increased to a similar extent by vitamin C and that of three post-translational enzymes, the carboxy- and amino-procollagen proteinases and lysyloxidase similarly increased. The mRNA of decorin was also stimulated, but elastin, and fibrillin 1 and 2 were not modified by the vitamin. The expression of matrix metalloproteinases 1, 2, and 9 was not significantly changed, but an increased level of tissue inhibitor of matrix metalloproteinase 1 mRNA was observed without modification of tissue inhibitor of matrix metalloproteinase 2 mRNA. The stimulating activity of topical vitamin C was most conspicuous in the women with the lowest dietary intake of the vitamin and unrelated to the level of actinic damage. The results indicate that the functional activity of the dermal cells is not maximal in postmenopausal women and can be increased. [less ▲]

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See detailCoordinated regulation of procollagens I and III and their post-translational enzymes by dissipation of mechanical tension in human dermal fibroblasts.
Lambert, Charles ULg; Colige, Alain ULg; Lapiere, C. M. et al

in European Journal of Cell Biology (2001), 80(7), 479-85

Mechanical tension governs fibroblast proliferation and survival and the homeostasis of the extracellular matrix to adapt its resistance to the mechanical requirements of the organs. To consolidate this ... [more ▼]

Mechanical tension governs fibroblast proliferation and survival and the homeostasis of the extracellular matrix to adapt its resistance to the mechanical requirements of the organs. To consolidate this view, we analysed the effect of tension release on the expression of molecules involved in the architecture and stabilisation of the collagen fibres, namely the procollagens type I and III, the amino- and carboxy-procollagen peptidases (N-pCP and C-pCP) and lysyl oxidase. Cells were cultured in conditions of high mechanical stress in monolayer on a collagen coat and under reduced tension by disruption of the cytoskeleton upon treatment with cytochalasin D in monolayer on a collagen coat or by integrin-mediated stress relaxation in a freely retracting collagen gel. The mRNAs were measured by quantitative RT-PCR monitored by simultaneous reverse-transcription and amplification of an original internal standard. Tension relaxation resulted in a decreased expression of the procollagens type I and III, of the two expressed forms of C-pCP, of the two forms of N-pCP and of lysyl oxidase. Type III collagen, known to control diameter of the fibres, was less down-regulated than type I collagen. Interestingly, the expression of the two alternatively spliced forms of the N-pCP was dissimilarly regulated. These data suggest that mechanical tension may modulate the stiffness of the extracellular matrix by controlling not only the level of expression of its fibrillar constituents but also that of the enzymes participating in their extracellular processing and mechanical stabilisation. [less ▲]

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See detailDistinct pathways in the over-expression of matrix metalloproteinases in human fibroblasts by relaxation of mechanical tension.
Lambert, Charles ULg; Colige, Alain ULg; Munaut, Carine ULg et al

in Matrix Biology (2001), 20(7), 397-408

The aim of the work was to analyze, on a comparative basis, the signaling pathways operating in the regulation of a panel of matrix metalloproteinases (MMP) expressed by human dermal fibroblasts submitted ... [more ▼]

The aim of the work was to analyze, on a comparative basis, the signaling pathways operating in the regulation of a panel of matrix metalloproteinases (MMP) expressed by human dermal fibroblasts submitted to mechanical stress relaxation by cytochalasin D (CD) and in a retracting collagen gel (RCG). The mRNA steady-state level of MMPs was measured by a quantitative RT-PCR procedure using a synthetic RNA as internal standard. In monolayer, most MMPs were barely detected, except MMP-2. Disruption of the actin stress fibers by CD induced a moderate increase of MMP-2 mRNA and a much larger stimulation of MMP-3, -9, -13 and -14 mRNAs. In RCG, a significant up-regulation of these MMPs was also observed although to a lower extent than in CD-treated monolayers. Among the investigated MMPs, the MMP-8 and -11 were not reproducibly detected. MMP-2 was processed to its active form both by CD and in RCG. The CD-induced up-regulation of gene expression was largely repressed by blocking protein synthesis by cycloheximide for all the MMPs, by inhibiting the tyrosine-kinases of the src family by herbimycin A for all MMPs, except MMP-2, and by inhibiting the TPA-inducible PKC isoforms by bisindoyl maleimide for all MMPs, except MMP-14. The up-regulation induced by stress relaxation in RCG was protein synthesis-dependent for MMP-2 and MMP-13, tyrosine kinases-dependent for MMP-3 and MMP-13, as previously described for MMP-1. Inhibiting TPA-inducible PKC did not affect any MMP in RCG except MMP-13, which was strongly induced. The processing of MMP-2 was tyrosine kinases-dependent but PKC-independent. Inhibitors of the ERK1,2 and p38 MAP kinases pathways diversely affected the MMPs expression. Inhibiting the Rho-kinase activity by Y-27632 was inactive. These results point to the potent regulation operated by the status of the cytoskeleton on the cell phenotype, and to distinct regulatory pathways involved in the control of different MMPs expression. [less ▲]

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