Mechanical strain induces a pro-fibrotic phenotype in human mitral valvular interstitial cells through RhoC/ROCK/MRTF-A and Erk1/2 signaling pathways.

The mitral valve is a complex multilayered structure populated by fibroblast-like cells, valvular interstitial cells (VIC) which are embedded in an extracellular matrix (ECM) scaffold and are submitted to the mechanical deformations affecting valve at each heartbeat, for an average of 40 million times per year. Myxomatous mitral valve (MMV) is the most frequent heart valve disease characterized by disruption of several valvular structures due to alterations of their ECM preventing the complete closure of the valve resulting in symptoms of prolapse and regurgitation. VIC and their ECM exhibit reciprocal dynamic processes between the mechanical signals issued from the ECM and the modulation of VIC phenotype responsible for ECM homeostasis of the valve. Abnormal perception and responsiveness of VIC to mechanical stress may induce an inappropriate adaptative remodeling of the valve progressively leading to MMV. To investigate the response of human VIC to mechanical strain and identify the molecular mechanisms of mechano-transduction in these cells, a cyclic equibiaxial elongation of 14% at the cardiac frequency of 1.16 Hz was applied to VIC by using a Flexercell-4000 T™ apparatus for increasing time (from 1 h to 8 h). We showed that cyclic stretch induces an early (1 h) and transient over-expression of TGFß2 and αSMA. CTGF, a profibrotic growth factor promoting the synthesis of ECM components, was strongly induced after 1 and 2 h of stretching and still upregulated at 8 h. The mechanical stress-induced CTGF up-regulation was dependent on RhoC, but not RhoA, as demonstrated by siRNA-mediated silencing approaches, and further supported by evidencing RhoC activation upon cell stretching and suppression of cell response by pharmacological inhibition of the effector ROCK1/2. It was also dependent on the MEK/Erk1/2 pathway which was activated by mechanical stress independently of RhoC and ROCK. Finally, mechanical stretching induced the nuclear translocation of myocardin related transcription factor-A (MRTF-A) which forms a transcriptional complex with SRF to promote the expression of target genes, notably CTGF. Treatment of stretched cultures with inhibitors of the identified pathways (ROCK1/2, MEK/Erk1/2, MRTF-A translocation) blocked CTGF overexpression and abrogated the increased MRTF-A nuclear translocation. CTGF is up-regulated in many pathological processes involving mechanically challenged organs, promotes ECM accumulation and is considered as a hallmark of fibrotic diseases. Pharmacological targeting of MRTF-A by newly developed inhibitors may represent a relevant therapy for MMV.

Propranolol sensitizes prostate cancer cells to glucose metabolism inhibition and prevents cancer progression.

Propranolol, a widely used non-selective beta-adrenergic receptor blocker, was recently shown to display anticancer properties. Its potential to synergize with certain drugs has been also outlined. However, it is necessary to take into account all the properties of propranolol to select a drug that could be efficiently combined with. Propranolol was reported to block the late phase of autophagy. Hence, we hypothesized that in condition enhancing autophagy flux, cancer cells should be especially sensitive to propranolol. 2DG, a glycolysis inhibitor, is an anti-tumor agent having limited effect in monotherapy notably due to induction of pro-survival autophagy. Here, we report that treatment of cancer cells with propranolol in combination with the glycolysis inhibitor 2DG induced a massive accumulation of autophagosome due to autophagy blockade. The propranolol +2DG treatment efficiently prevents prostate cancer cell proliferation, induces cell apoptosis, alters mitochondrial morphology, inhibits mitochondrial bioenergetics and aggravates ER stress in vitro and also suppresses tumor growth in vivo. Our study underlines for the first time the interest to take advantage of the ability of propranolol to inhibit autophagy to design new anti-cancer therapies.

Circulating microRNAs signature correlates with positive [18F]fluorodeoxyglucose-positron emission tomography in patients with abdominal aortic aneurysm.

BACKGROUND: Prediction of abdominal aortic aneurysm (AAA) rupture is a challenging issue. Small noncoding microRNAs (miRNAs) are potent regulators of gene expression and are considered as valuable circulating biomarkers. Recently, [18F]fluorodeoxyglucose (FDG) uptake detected by positron emission tomography (PET) in AAA was correlated with cellular and molecular alterations involved in wall instability and its potential rupture. Our study aimed at identifying circulating miRNAs correlated with a positive PET that could help discriminate patients at high risk of rupture. METHODS: The level of 372 miRNAs was evaluated by polymerase chain reaction array in plasma from 35 AAA patients displaying no FDG uptake (A0) and 22 patients with a positive PET uptake (A+). The modulated miRNAs were validated by quantitative polymerase chain reaction and measured in aneurysmal tissues from both groups of patients. RESULTS: Six circulating miRNAs were found significantly modulated in A+ vs A0 patients. They were significantly correlated not only between them but also with the intensity of FDG uptake. Two of them correlated also with the AAA diameter. These miRNAs displayed significant discriminating power between the A+ and A0 groups as determined by receiver operating characteristic curves. Three downregulated circulating miRNAs (miR-99b-5p, miR-125b-5p, and miR-204-5p) were also significantly reduced in the aneurysmal tissue, specifically in the FDG-uptake site, compared with a negative zone in the same aneurysm and with A0 aneurysms. They were further significantly inversely correlated with the expression, at the positive uptake site, of some of their potential gene targets, most notably matrix metalloproteinase 13. CONCLUSIONS: Six miRNAs were identified as potential new circulating biomarkers of PET+ AAA. Three of these were similarly modulated in the metabolically active aneurysmal wall and might be directly involved in AAA instability.

18F-FDG PET/CT in the Management of Aortitis.

BACKGROUND: Aortitis is a generic term defined as an inflammatory condition involving the aortic wall, of infectious or noninfectious origin. This inflammatory process may deteriorate the aortic wall, resulting in potentially life-threatening vascular complications. Therefore, it is important to establish a diagnosis as early as possible. PATIENTS AND METHODS: During a 4-year period, 428 consecutive patients referred to our department for aortic diseases underwent FDG PET/CT examinations. Among these, 18 patients (4.2%) were suspected to have aortitis. All of them had an initial positive FDG PET/CT uptake occurring in the aorta and major branches as evaluated by visual analysis of images and assessed with the final diagnosis of aortitis. During follow-up, after surgery and/or upon immunosuppressive treatment, each of these patients underwent a second PET/CT that was compared with the initial evaluation. In all cases, normalization of FDG uptake was correlated with clinical improvement. CONCLUSIONS: Our study aimed to illustrate the potential clinical value of functional monitoring with PET/CT in the management of aortitis. FDG PET/CT constitutes a valuable imaging modality to establish an early diagnosis, monitor disease progression and treatment, and evaluate vascular complication and relapse. We highlight the importance of an early detection of inflammatory large-vessel pathology, which may represent a major threat.

Elastin density: Link between histological and biomechanical properties of vaginal tissue in women with pelvic organ prolapse?

INTRODUCTION AND HYPOTHESIS: The aim of the study was to correlate histological and biomechanical characteristics of the vaginal wall in women with pelvic organ prolapse (POP). METHODS: Tissue samples were collected from the anterior [point Ba; POP Questionnaire (POP-Q)] and/or posterior (point Bp; POP-Q) vaginal wall of 15 women who underwent vaginal surgery for POP. Both histological and biomechanical assessments were performed from the same tissue samples in 14 of 15 patients. For histological assessment, the density of collagen and elastin fibers was determined by combining high-resolution virtual imaging and computer-assisted digital image analysis. For biomechanical testing, uniaxial tension tests were performed to evaluate vaginal tissue stiffness at low (C0) and high (C1) deformation rates. RESULTS: Biomechanical testing highlights the hyperelastic behavior of the vaginal wall. At low strains (C0), vaginal tissue appeared stiffer when elastin density was low. We found a statistically significant inverse relationship between C0 and the elastin/collagen ratio (p = 0.048) in the lamina propria. However, at large strain levels (C1), no clear relationship was observed between elastin density or elastin/collagen ratio and stiffness, likely reflecting the large dispersion of the mechanical behavior of the tissue samples. CONCLUSION: Histological and biomechanical properties of the vaginal wall vary from patient to patient. This study suggests that elastin density deserves consideration as a relevant factor of vaginal stiffness in women with POP.

Rac1 GTPase silencing counteracts microgravity-induced effects on osteoblastic cells.

Bone cells exposed to real microgravity display alterations of their cytoskeleton and focal adhesions, two major mechanosensitive structures. These structures are controlled by small GTPases of the Ras homology (Rho) family. We investigated the effects of RhoA, Rac1, and Cdc42 modulation of osteoblastic cells under microgravity conditions. Human MG-63 osteoblast-like cells silenced for RhoGTPases were cultured in the automated Biobox bioreactor (European Space Agency) aboard the Foton M3 satellite and compared to replicate ground-based controls. The cells were fixed after 69 h of microgravity exposure for postflight analysis of focal contacts, F-actin polymerization, vascular endothelial growth factor (VEGF) expression, and matrix targeting. We found that RhoA silencing did not affect sensitivity to microgravity but that Rac1 and, to a lesser extent, Cdc42 abrogation was particularly efficient in counteracting the spaceflight-related reduction of the number of focal contacts [-50% in silenced, scrambled (SiScr) controls vs. -15% for SiRac1], the number of F-actin fibers (-60% in SiScr controls vs. -10% for SiRac1), and the depletion of matrix-bound VEGF (-40% in SiScr controls vs. -8% for SiRac1). Collectively, these data point out the role of the VEGF/Rho GTPase axis in mechanosensing and validate Rac1-mediated signaling pathways as potential targets for counteracting microgravity effects.

Changes in elastin density in different locations of the vaginal wall in women with pelvic organ prolapse.

INTRODUCTION AND HYPOTHESIS: The purpose of this study was to analyze the histomorphometric properties of the vaginal wall in women with pelvic organ prolapse (POP). METHODS: In 15 women undergoing surgery for POP, full-thickness biopsies were collected at two different sites of location from the anterior and/or posterior vaginal wall. Properties of the precervical area (POP-Q point C/D) were compared with the most distal portion of the vaginal wall (POP-Q point Ba/Bp) using histological staining and immunohistochemistry. The densities of total collagen fibers, elastic fibers, smooth muscle cells, and blood vessels were determined by combining high-resolution virtual imaging and computer-assisted digital image analysis. RESULTS: The mean elastin density was significantly decreased in the lamina propria and muscularis layer of the vaginal wall from the most distal portion of the prolapsed vaginal wall compared with the precervical area. This difference was statistically significant in the lamina propria for both anterior (8.4 ± 1.2 and 12.1 ± 2.0, p = 0.048) and posterior (6.8 ± 0.5 and 10.1 ± 1.4, p = 0.040) locations, and in the muscularis for the anterior (5.2 ± 0.4 and 8.4 ± 1.2, p = 0.009) vaginal wall. There were no statistically significant differences in the mean densities of collagen fibers, smooth muscle cells or blood vessels between the two locations. CONCLUSIONS: In this study, we observed changes in elastin density in two different locations of the vaginal wall from women with POP. The histomorphometric properties of the vaginal wall can be variable from one place to another in the same patient. This result supports the existence of most vulnerable locations within the vaginal wall and the potential benefit of site-specific prolapse surgery.

Effects of mild cold shock (25°C) followed by warming up at 37°C on the cellular stress response.

Temperature variations in cells, tissues and organs may occur in a number of circumstances. We report here that reducing temperature of cells in culture to 25°C for 5 days followed by a rewarming to 37°C affects cell biology and induces a cellular stress response. Cell proliferation was almost arrested during mild hypothermia and not restored upon returning to 37°C. The expression of cold shock genes, CIRBP and RBM3, was increased at 25°C and returned to basal level upon rewarming while that of heat shock protein HSP70 was inversely regulated. An activation of pro-apoptotic pathways was evidenced by FACS analysis and increased Bax/Bcl2 and BclX(S/L) ratios. Concomitant increased expression of the autophagosome-associated protein LC3II and AKT phosphorylation suggested a simultaneous activation of autophagy and pro-survival pathways. However, a large proportion of cells were dying 24 hours after rewarming. The occurrence of DNA damage was evidenced by the increased phosphorylation of p53 and H2AX, a hallmark of DNA breaks. The latter process, as well as apoptosis, was strongly reduced by the radical oxygen species (ROS) scavenger, N-acetylcysteine, indicating a causal relationship between ROS, DNA damage and cell death during mild cold shock and rewarming. These data bring new insights into the potential deleterious effects of mild hypothermia and rewarming used in various research and therapeutical fields.

Emerging pathogenic mechanisms in human myxomatous mitral valve: lessons from past and novel data.

INTRODUCTION: Myxomatous mitral valve is one of the most common heart valves diseases in human and has been well characterized at a functional and morphological level. Diseased valves are thickened as a result of extracellular matrix remodeling and proteoglycans accumulation accompanied by the disruption of the stratified structures of the leaflets. METHODS: Global transcriptomic analysis was used as a start-up to investigate potential pathogenic mechanisms involved in the development of the human idiopathic myxomatous mitral valve, which have been elusive for many years. RESULTS: These prospective analyses have highlighted the potential role of apparently unrelated molecules in myxomatous mitral valve such as members of the transforming growth factor-ß superfamily, aggrecanases of the "a disintegrin and metalloprotease with thrombospondin repeats I" family, and a weakening of the protection against oxidative stress. We have integrated, in this review, recent transcriptomic data from our laboratory [A. Hulin, C.F. Deroanne, C.A. Lambert, B. Dumont, V. Castronovo, J.O. Defraigne, et al. Metallothionein-dependent up-regulation of TGF-beta2 participates in the remodelling of the myxomatous mitral valve. Cardiovasc Res 2012;93:480-489] and from the publication of Sainger et al. [R. Sainger, J.B. Grau, E. Branchetti, P. Poggio, W.F. Seefried, B.C. Field, et al. Human myxomatous mitral valve prolapse: role of bone morphogenetic protein 4 in valvular interstitial cell activation. J Cell Physiol 2012;227:2595-2604] with existing literature and information issued from the study of monogenic syndromes and animal models. CONCLUSION: Understanding cellular alterations and molecular mechanisms involved in myxomatous mitral valve should help at identifying relevant targets for future effective pharmacological therapy to prevent or reduce its progression.

Dissection of Iliac Artery in a Patient With Autosomal Dominant Polycystic Kidney Disease: A Case Report.

Autosomal dominant polycystic kidney disease (ADPKD) is a risk factor for several cardiovascular disorders such as intracranial aneurysm or aortic dissection, preferentially occurring at the thoracic or abdominal level. A 47-year-old man suffering from ADPKD had renal transplantation. Sixteen hours after surgery, he presented with left leg pain. Clinical and ultrasound examination revealed thrombosis of the external left iliac artery. Therefore, we decided to perform intra-arterial angiography to evaluate the possibility of an endovascular treatment. Aorto-femorography showed an obstruction of the external left iliac artery that was found during emergency surgery, consecutive to a dissection, which occurred following the surgery for kidney transplantation. The resected segment of the dissected vessel was analyzed by histology. Collagen fibers organization and density in the adventitia and smooth muscle cells density in the media were similar in the dissected and a normal artery from a healthy donor. By contrast, an almost complete disappearance and fragmentation of elastic lamellae were observed in the media of the dissected artery, most likely responsible for the weakening of the arterial wall and its dissection. Association between ADPKD and single dissection of the iliac artery has been rarely reported. Relationship between inactivation of polycystin/PKD genes and elastic fibers degradation through elevated TGFß signaling and matrix metalloproteinase 2 (MMP2) elastolytic activity, as recently reported in ADPKD, would be worth investigating.

Effects of platelet-rich plasma (PRP) on the healing of Achilles tendons of rats.

Platelet-rich plasma (PRP) contains growth factors involved in the tissular healing process. The aim of the study was to determine if an injection of PRP could improve the healing of sectioned Achilles tendons of rats. After surgery, rats received an injection of PRP (n = 60) or a physiological solution (n = 60) in situ. After 5, 15, and 30 days, 20 rats of both groups were euthanized and 15 collected tendons were submitted to a biomechanical test using cryo-jaws before performing transcriptomic analyses. Histological and biochemical analyses were performed on the five remaining tendons in each group. Tendons in the PRP group were more resistant to rupture at 15 and 30 days. The mechanical stress was significantly increased in tendons of the PRP group at day 30. Histological analysis showed a precocious deposition of fibrillar collagen at day 5 confirmed by a biochemical measurement. The expression of tenomodulin was significantly higher at day 5. The messenger RNA levels of type III collagen, matrix metalloproteinases 2, 3, and 9, were similar in the two groups at all time points, whereas type I collagen was significantly increased at day 30 in the PRP group. In conclusion, an injection of PRP in sectioned rat Achilles tendon influences the early phase of tendon healing and results in an ultimately stronger mechanical resistance.

Metallothionein-dependent up-regulation of TGF-ß2 participates in the remodelling of the myxomatous mitral valve.

AIMS: Although an excessive extracellular matrix remodelling has been well described in myxomatous mitral valve (MMV), the underlying pathogenic mechanisms remain largely unknown. Our goal was to identify dysregulated genes in human MMV and then to evaluate their functional role in the progression of the disease. METHODS AND RESULTS: Dysregulated genes were investigated by transcriptomic, immunohistochemistry, and western blot analyses of the P2 segment collected from human idiopathic MMV during valvuloplasty (n = 23) and from healthy control valves (n = 17). The most striking results showed a decreased expression of two families of genes: the metallothioneins-1 and -2 (MT1/2) and members of the ADAMTS. The mechanistic consequences of the reduced level of MT1/2 were evaluated by silencing their expression in normal valvular interstitial cells (VICs) cultures. The knock-down of MT1/2 resulted in the up-regulation of transforming growth factor-beta 2 (TGF-ß2). Most importantly, TGF-ß2 was also found significantly increased in MMV tissues. The activation of VICs in vitro by TGF-ß2 induced a down-regulation of ADAMTS-1 and an accumulation of versican as observed in human MMV. CONCLUSION: Our studies demonstrate for the first time that MMV are characterized by reduced levels of MT1/2 accompanied by an up-regulation of TGF-ß2. In turn, increased TGF-ß2 signalling induces down-regulation of aggrecanases and up-regulation of versican, two co-operating processes that potentially participate in the development of the pathology.

Development of a chitosan nanofibrillar scaffold for skin repair and regeneration.

The final goal of the present study was the development of a 3-D chitosan dressing that would shorten the healing time of skin wounds by stimulating migration, invasion, and proliferation of the relevant cutaneous resident cells. Three-dimensional chitosan nanofibrillar scaffolds produced by electrospinning were compared with evaporated films and freeze-dried sponges for their biological properties. The nanofibrillar structure strongly improved cell adhesion and proliferation in vitro. When implanted in mice, the nanofibrillar scaffold was colonized by mesenchymal cells and blood vessels. Accumulation of collagen fibrils was also observed. In contrast, sponges induced a foreign body granuloma. When used as a dressing covering full-thickness skin wounds in mice, chitosan nanofibrils induced a faster regeneration of both the epidermis and dermis compartments. Altogether our data illustrate the critical importance of the nanofibrillar structure of chitosan devices for their full biocompatibility and demonstrate the significant beneficial effect of chitosan as a wound-healing biomaterial.

RhoGDIα-dependent balance between RhoA and RhoC is a key regulator of cancer cell tumorigenesis.

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 α (RhoGDIα) and the overexpression of a RhoA mutant unable to bind RhoGDIα suggested that the effect of RhoC silencing is indirect and results from the up-regulation of the RhoA level through competition for RhoGDIα. This study demonstrates the dynamic balance inside the RhoGTPase network and illustrates its biological relevance in cancer progression.

Histological and transcriptional study of angiogenesis and lymphangiogenesis in uninvolved skin, acute pinpoint lesions and established psoriasis plaques: an approach of vascular development chronology in psoriasis.

BACKGROUND: Dysregulation of angiogenesis and lymphangiogenesis could participate in psoriasis pathogenesis. Analysis of nascent psoriasis lesions should help at identifying early vascular anomalies. OBJECTIVE: To analyse vascular development, angiogenesis and lymphangiogenesis markers expression in uninvolved skin in psoriatic patients (N), early psoriasis lesions or pinpoints (PP) and psoriasis plaques (PSO). METHODS: Skin biopsies were taken in 17 patients in N and in PSO and/or PP. The mRNA steady-state level of angiogenesis and lymphangiogenesis markers was measured by RT-PCR. Immunohistochemistry was performed for von Willebrand factor, podoplanin, Ki-67 and VEGFR3. Blood (BV) and lymphatic (LV) vessels expansion was measured by computer-assisted morphometry. RESULTS: Clinical and epidermal aspects indicated that PP are intermediate between N and PSO. While total BV area was already increased in PP similarly to PSO as compared to N, LV area in PP was intermediate between N and PSO. Mean LV size was identical in N and PP and increased in PSO, mean BV size in PP being intermediate between N and PSO. VEGF-A 189 variant was increased in PP as compared to N and PSO. As compared to N, angiogenesis markers (VEGF-A isoforms, PlGF, VEGFR2, NRP-1), VEGF-C and NRP-2 were similarly increased in PP and PSO. Keratin 16 and the lymphangiogenesis markers (VEGFR3, prox-1) were intermediate in PP. CONCLUSION: These data suggest that the expansion of lymphatic vessels occurs after blood vascular development in psoriasis. Expansion of BV in PP could be followed by vessel enlargement during progression to PSO, in parallel with a decreased VEGF-A 189/VEGF-A 121 balance in plaques.

Human bone marrow adipocytes block granulopoiesis through neuropilin-1-induced granulocyte colony-stimulating factor inhibition.

Adipocytes are part of hematopoietic microenvironment, even though up to now in humans, their role in hematopoiesis is still questioned. We have previously shown that accumulation of fat cells in femoral bone marrow (BM) coincides with increased expression of neuropilin-1 (NP-1), while it is weakly expressed in hematopoietic iliac crest BM. Starting from this observation, we postulated that adipocytes might exert a negative effect on hematopoiesis mediated through NP-1. To test this hypothesis, we set up BM adipocytes differentiated into fibroblast-like fat cells (FLFC), which share the major characteristics of primitive unilocular fat cells, as an experimental model. As expected, FLFCs constitutively produced macrophage colony stimulating factor and induced CD34(+) differentiation into macrophages independently of cell-to-cell contact. By contrast, granulopoiesis was hampered by cell-to-cell contact but could be restored in transwell culture conditions, together with granulocyte colony stimulating factor production. Both functions were also recovered when FLFCs cultured in contact with CD34(+) cells were treated with an antibody neutralizing NP-1, which proved its critical implication in contact inhibition. An inflammatory cytokine such as interleukin-1 beta or dexamethasone modulates FLFC properties to restore granulopoiesis. Our data provide the first evidence that primary adipocytes exert regulatory functions during hematopoiesis that might be implicated in some pathological processes. Disclosure of potential conflicts of interest is found at the end of this article.

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.

Domains and maturation processes that regulate the activity of ADAMTS-2, a metalloproteinase cleaving the aminopropeptide of fibrillar procollagens types I-III and V.

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.

Differential expression of vascular endothelial growth factor and its receptors in hematopoietic and fatty bone marrow: evidence that neuropilin-1 is produced by fat cells.

Vascular endothelial growth factor (VEGF), its receptors (VEGFR-1, VEGFR-2) and neuropillin-1 (NRP-1) are expressed at variable levels in bone marrow. NRP-1expression is higher in fatty bone marrow than in hematopoietic marrow. Adipocytes are responsible for NRP-1 expression suggesting that they may play a role in hematopoiesis by producing NRP-1 or that NRP-1 may regulate adipocyte activity.