Modulation of adipose tissue expression of murine matrix metalloproteinases and their tissue inhibitors with obesity

The potential role of the matrix metalloproteinase (MMP) system in the pathophysiology of the adipose tissue was investigated in a mouse model of nutritionally induced obesity. mRNA levels of 16 MMPs and 4 tissue inhibitors of MMPs (TIMPs) were measured by semiquantitative RT-PCR in adipose tissue isolated from mice maintained for 15 weeks on a standard or high-fat diet. In mice on standard diet, with the exception of MMP-8, all MMP and TIMP transcripts were detected in both gonadal and subcutaneous depots. In obese mice, the expression of MMP-3, -11, -12, -13, and -14 and TIMP-1 mRNAs was upregulated, whereas that of MMP-7, -9, -16, and -24 and TIMP-4 was downregulated. Most MMP and TIMP mRNAs were expressed at higher levels in stromal-vascular cells than in mature adipocytes. Analysis of adipose tissue by in situ fluorescent zymography revealed MMP-dependent proteolytic activities, demonstrating the presence of active MMPs in the intact tissue. In vitro conversion of adipogenic 3T3-F442A cells into mature adipocytes was associated with substantial modulations of MMP and TIMP expression. Moreover, this in vitro adipogenesis was reduced in the presence of a synthetic MMP inhibitor. Thus, the adipose tissue expresses a large array of MMPs and TIMPs, which modulate adipocyte differentiation

ADAMTS2 and ADAMTS14 substitute ADAMTS3 in adults for proVEGFC activation and lymphatic homeostasis.

The capacity of ADAMTS3 to cleave proVEGFC into active VEGFC able to bind its receptors and to stimulate lymphangiogenesis has been clearly established during the embryonic life. However such function of ADAMTS3 is unlikely to persist in adulthood because of its restricted expression pattern after birth. Since ADAMTS2 and ADAMTS14 are closely related to ADAMTS3 and are mainly expressed in connective tissues where the lymphatic network extends, we hypothesized that they could substitute ADAMTS3 during adulthood in mammals for proteolytic activation of proVEGFC. Here, we demonstrated that ADAMTS2 and ADAMTS14 are able to process proVEGFC and activate the downstream pathway as efficiently as ADAMTS3. In vivo, adult mice lacking Adamts2 develop skin lymphedema due to a reduction of the density and diameter of lymphatic vessels leading to a decrease of lymphatic functionality, while genetic ablation of Adamts14 has no impact. In a model of thermal cauterization of cornea, lymphangiogenesis was significantly reduced in Adamts2 and Adamts14 knockout mice, and further repressed in Adamts2/Adamts14 double knockout mice. In summary, we have demonstrated that ADAMTS2 and ADAMTS14 are as efficient as ADAMTS3 for proVEGFC activation and are involved in the homeostasis of the lymphatic vasculature in adulthood, both in physiological and pathological processes

Regulation of procollagen amino-propeptide processing during mouse embryogenesis by specialization of homologous ADAMTS proteases: insights on collagen biosynthesis and dermatosparaxis

Mutations in ADAMTS2, a procollagen amino-propeptidase, cause severe skin fragility, designated as dermatosparaxis in animals, and a subtype of the Ehlers-Danlos syndrome (dermatosparactic type or VIIC) in humans. Not all collagen-rich tissues are affected to the same degree, which suggests compensation by the ADAMTS2 homologs ADAMTS3 and ADAMTS14. In situ hybridization of Adamts2, Adamts3 and Adamts14, and of the genes encoding the major. brillar collagens, Col1a1, Col2a1 and Col3a1, during mouse embryogenesis, demonstrated distinct tissue-specific, overlapping expression patterns of the protease and substrate genes. Adamts3, but not Adamts2 or Adamts14, was co-expressed with Col2a1 in cartilage throughout development, and with Col1a1 in bone and musculotendinous tissues. ADAMTS3 induced procollagen I processing in dermatosparactic. broblasts, suggesting a role in procollagen I processing during musculoskeletal development. Adamts2, but not Adamts3 or Adamts14, was co-expressed with Col3a1 in many tissues including the lungs and aorta, and Adamts2(-/-) mice showed widespread defects in procollagen III processing. Adamts2(-/-) mice had abnormal lungs, characterized by a decreased parenchymal density. However, the aorta and collagen fibrils in the aortic wall appeared normal. Although Adamts14 lacked developmental tissue-specific expression, it was co-expressed with Adamts2 in mature dermis, which possibly explains the presence of some processed skin procollagen in dermatosparaxis. The data show how evolutionarily related proteases with similar substrate preferences may have distinct biological roles owing to tissue specific gene expression, and provide insights into collagen biosynthesis and the pathobiology of dermatosparaxis

Matrix and serine protease expression during leukemic cell differentiation induced by aclacinomycin and all-trans-retinoic acid

In myeloid leukemia, immature leukemic cells are able to egress into peripheral blood to infiltrate extra-medullary organs. We therefore analyzed the migrating and invasive potential of human HL-60 and NB4 cell lines, representative of acute myelogenous leukemia, their ability to express matrix metalloproteases (MMPs), tissue inhibitors of metalloproteases (TIMPs) and urokinase plasminogen activator (uPA) in response to differentiating agents. Granulocytic differentiation by all-trans-retinoic acid (ATRA) and aclacinomycin (ACLA) strongly increased HL-60 and NB4 cell migration and invasion. At mRNA and protein levels, these cell lines produced significant amounts of MMP-9 (HL-60 < NB4). Granulocytic differentiation by ACLA increased both pro and active forms of MMP-9 whereas ATRA decreased them and stimulated uPA mRNAs. TIMP-1, the physiological MMP inhibitor, increased during granulocytic differentiation whereas TIMP-2 did not significantly vary. Use of Batimastat and aprotinin suggests that ATRA was active by modulating the uPA system while ACLA interfered with MMP expression. In conclusion, our data demonstrate that HL-60 and NB4 cells express MMPs and uPA which are differentially regulated by the differentiating agents ATRA and ACLA and suggest the clinical usefulness of MMPs and serine protease inhibitors in the prophylaxis and treatment of the ATRA syndrome. (C) 2002 Elsevier Science Inc. All rights reserved

MMP-9 regulates both positively and negatively collagen gel contraction - A nonproteolytic function of MMP-9

peer reviewedaudience: researcher, professionalObjective: Constrictive remodeling accounts for lumen loss in postangioplasty restenosis. Matrix metalloproteinase-9 (MMP-9) has been shown to prevent constrictive remodeling in vivo. To investigate potential mechanisms for this observation, we investigated the role of MMP-9 in smooth muscle cell (SMC)-mediated collagen gel contraction, an in vitro model of constrictive remodeling. Methods: Fischer rat SMCs were stably transfected with a construct-expressing rat-MMP-9 under the control of a tetracycline (Tet)-off promoter. SMCs were seeded in type 1 collagen gels (2.4 mg/ml) in the presence or not of tetracycline (1 mu g/ml), and gel contraction was defined as the percentage of retraction of the collagen gel. The depletion of MMP-9 was obtained by using siRNA targeting MMP-9 mRNA or a blocking antibody. Results: Gel contraction was significantly reduced at all times when MMP-9 was overexpressed (Tet-) as compared with the control condition (Tet+). However, MMP-9 depletion of control (Tet+) SMCS (using siRNA or antibody) also inhibited gel contraction. To resolve the apparent discrepancy and determine if MMP-9 exerts a dose-dependent biphasic effect on gel contraction, conditioned medium and purified rat-MMP-9 were prepared. Gel contraction was significantly increased by addition of 0.8 mg/ml of MMP-9, while high concentrations of MMP-9 (>= 100 mg/ml) inhibited contraction. The addition of BB94 and TIMP-1 did not alter the inhibitory or stimulatory effect of MMP-9. Conclusions: Our data Suggest that MMP-9, independent of its proteolytic function, has a biphasic effect on SMC-mediated collagen gel contraction. Understanding the different roles of MMP-9 Should allow the development of better therapeutic strategies for restenotic vascular disease. (c) 2004 European Society of Cardiology. Published by Elsevier B.V. All rights reserved

Newly identified biologically active and proteolysis-resistant VEGF-A isoform VEGF111 is induced by genotoxic agents

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

Stimulation of matrix metalloproteinase-9 expression in human fibrosarcoma cells by synthetic matrix metalloproteinase inhibitors.

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

TIMP-2 and PAI-1 mRNA levels are lower in aneurysmal as compared to athero-occlusive abdominal aortas.

peer reviewedOBJECTIVE: 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

Microgravity triggers ferroptosis and accelerates senescence in the MG-63 cell model of osteoblastic cells.

peer reviewedIn space, cells sustain strong modifications of their mechanical environment. Mechanosensitive molecules at the cell membrane regulate mechanotransduction pathways that induce adaptive responses through the regulation of gene expression, post-translational modifications, protein interactions or intracellular trafficking, among others. In the current study, human osteoblastic cells were cultured on the ISS in microgravity and at 1 g in a centrifuge, as onboard controls. RNAseq analyses showed that microgravity inhibits cell proliferation and DNA repair, stimulates inflammatory pathways and induces ferroptosis and senescence, two pathways related to ageing. Morphological hallmarks of senescence, such as reduced nuclear size and changes in chromatin architecture, proliferation marker distribution, tubulin acetylation and lysosomal transport were identified by immunofluorescence microscopy, reinforcing the hypothesis of induction of cell senescence in microgravity during space flight. These processes could be attributed, at least in part, to the regulation of YAP1 and its downstream effectors NUPR1 and CKAP2L.Cytoskeleto