Fibroblastic Growth Factor-2 Research Articles

Melatonin modulates the in vitro angiogenesis of granulosa cells collected from women with marital infertility for IVF

Melatonin concentration is
 several folds higher in the follicular fluid than that in blood suggesting an
 important role of this molecule on follicular physiology. However, the actions
 of melatonin on angiogenesis in granulosa cells are currently unknown. In this
 study, we have specifically investigated the potential effects of melatonin on
 the angiogenesis in granulosa cells from female individuals with marital
 infertility. Sixty patients who were submitted to the in vitrofertilization were included. The granulosa-luteal cells of these females were
 collected for cell culture. The cells were divided into four groups: a) vehicle
 (control); b) 0.1 µM melatonin; c) 1 µM melatonin; d) 10 µM melatonin treated
 groups, respectively. After a period of 10 days of culture, expression of genes
 involved in the angiogenesis signaling pathway were analyzed by Real-Time PCR
 and Western Blot assays. The results showed that the expressions of FGF1(fibroblast growth factor 1), IL1B (interleukin 1-beta), VEGFR-2(type 2 vascular-endothelial growth factor receptor), and TGFB1 (tumor
 growth factor 1- beta) were significantly upregulated in melatonin treated
 groups compared to the control. In contrast, the expressions of HIF-1A(hypoxia-inducing factor 1-alpha), FGF2 (fibroblastic growth factor 2), IGF-1(insulin-like growth factor 1), and VEGFA (vascular endothelial growth
 factor alpha) were significantly downregulated by melatonin compared to the
 control. The results suggest that melatonin modulates angiogenesis of granulosa
 cells from women with marital infertility. The underlining mechanism may relate
 to melatonin maintaining the homeostasis of VEGF, especially at a low dose of
 melatonin.

Combination treatment of Danggui Buxue Decoction and endothelial progenitor cells can enhance angiogenesis in rats with focal cerebral ischemia and hyperlipidemia

Ethnopharmacological relevanceDanggui Buxue Decoction (DBD) is a classic prescription of traditional Chinese medicine that is mainly used for treating clinical anemia for more than 800 years. This prescription has been utilized for nourishing “Qi” and enriching “Blood” for women suffering from menopausal symptoms. Meanwhile, DBD has the role of improving angiogenesis and promoting the neuroprotective functions. Bone marrow-derived endothelial progenitor cells (EPCs) was suboptimal to treat the focal cerebral ischemia (FCI). Thus, it's may be a novel strategy of DBD combined with EPCs transplantation for the FCI. Aim of the studyTo investigate the mechanistic effects of DBD in combination with EPCs transplantation to improve behavioral function of the FCI and hyperlipidemia. Materials and methodsWe used rats with hyperlipidemia to develop a FCI model using photo-thrombosis, and treated the DBD in combination with EPCs transplantation. We adopted the Modified Neurological Severity Score to evaluate the neurological deficit, undertook the 2,3,5-triphenyltetrazolium chloride staining to calculate the total infarct volume. We carried out the RT-qPCR, Immunohistochemical analyses, TUNEL, ELISA, and Western blotting to measure the gene and protein levels which related to anti-apoptosis mechanisms and angiogenesis. ResultsAdministration of DBD in combination with EPCs transplantation was found to improve behavioral function, reducing the infarct volume and decrease the level of total-cholesterole (TC) and low-density lipoprotein-cholesterol (LDL-C). Treatment of DBD plus EPCs increased the mRNA and protein expression of vascular endothelial growth factor A, fibroblastic growth factor-2, and angiopoietin-1 and decreased the apoptosis of endothelial cells by activating the phosphoinositide 3-kinase/protein kinase B/Bcl-xL/Bcl-2 associated death promoter (PI3K/Akt/BAD) pathway and promoting activation of the extracellular signal-regulated kinase (ERK) pathway, which induced angiogenesis directly. ConclusionsOur findings provided that DBD administration combined with EPCs transplantation promoted reconstruction of nervous function. This was achieved by enhancing expression of the growth factors related to anti-apoptosis mechanisms and angiogenesis thanks to regulation of the PI3K/Akt/BAD and ERK signaling pathways, and might be relate to the lowering of TC and LDL-C levels.

Effects of Vitamin E on the Epithelial-Mesenchymal Transition in Testicular Development Exposed to Valproic Acid

In testicular differentiation, somatic cells must adopt a specific destiny towards sustentacular, peritubular and interstitial cells, being fundamental for the morphogenesis of seminiferous tubules, mediated by morphogens such as Desert Hedgehog (DHH), insulin-like growth factor-1 (IGF-1) and fibroblastic growth factor 2 (FGF-2). Its alteration could be related to failures in the development mechanisms, such as those caused by valproic acid (VPA), which can be reversed with vitamin E (VE). The objective of the study was to evaluate the epithelial-mesenchymal transition (EMT) in the testicular development of mice exposed to VPA and VE. 12 groups of pregnant female mice were formed that were separated by days post-coital (dpc) at 12.5 dpc, 17.5 dpc and 6 weeks postnatal, each one subdivided into 4 groups of 5 pregnant women each. Subgroups received different treatments from the beginning to the end of gestation orally: 600 mg/kg of VPA, 600 mg/kg of VPA and 200 IU of VE, 200 IU of VE and the control group 0.3 mL of 0.9% physiological solution. Immunohistochemistry was performed for the detection of DHH, IGF-1 and FGF-2. Immunolocalization of DHH was observed in all stages, with more evident significant differences in integrated optical density (IOD) and percentage of immunoreaction area at 6 weeks postnatal, being lower in the VPA group. In IGF-1, lower intensity and distribution of immunostaining was observed in the fetal and pubertal stages in the VPA groups, a similar situation with FGF-2, but only evident at 17.5 dpc, with significant differences. These results demonstrate that VPA can alter EMT between somatic cells in testicular development, with VE being an agent capable of attenuating this process.

CD45+ Cells Present Within Mesenchymal Stem Cell Populations Affect Network Formation of Blood-Derived Endothelial Outgrowth Cells.

Mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) represent promising cell sources for angiogenic therapies. There are, however, conflicting reports regarding the ability of MSCs to support network formation of endothelial cells. The goal of this study was to assess the ability of human bone marrow-derived MSCs to support network formation of endothelial outgrowth cells (EOCs) derived from umbilical cord blood EPCs. We hypothesized that upon in vitro coculture, MSCs and EOCs promote a microenvironment conducive for EOC network formation without the addition of angiogenic growth supplements. EOC networks formed by coculture with MSCs underwent regression and cell loss by day 10 with a near 4-fold and 2-fold reduction in branch points and mean segment length, respectively, in comparison with networks formed by coculture vascular smooth muscle cell (SMC) cocultures. EOC network regression in MSC cocultures was not caused by lack of vascular endothelial growth factor (VEGF)-A or changes in TGF-β1 or Ang-2 supernatant concentrations in comparison with SMC cocultures. Removal of CD45+ cells from MSCs improved EOC network formation through a 2-fold increase in total segment length and number of branch points in comparison to unsorted MSCs by day 6. These improvements, however, were not sustained by day 10. CD45 expression in MSC cocultures correlated with EOC network regression with a 5-fold increase between day 6 and day 10 of culture. The addition of supplemental growth factors VEGF, fibroblastic growth factor-2, EGF, hydrocortisone, insulin growth factor-1, ascorbic acid, and heparin to MSC cocultures promoted stable EOC network formation over 2 weeks in vitro, without affecting CD45 expression, as evidenced by a lack of significant differences in total segment length (p=0.96). These findings demonstrate the ability of MSCs to support EOC network formation correlates with removal of CD45+ cells and improves upon the addition of soluble growth factors.

Cartilage turnover reflected by metabolic processing of type II collagen: a novel marker of anabolic function in chondrocytes.

The aim of this study was to enable measurement of cartilage formation by a novel biomarker of type II collagen formation. The competitive enzyme-linked immunosorbent assay (ELISA) Pro-C2 was developed and characterized for assessment of the beta splice variant of type II procollagen (PIIBNP). This is expected to originate primarily from remodeling of hyaline cartilage. A mouse monoclonal antibody (Mab) was raised in mouse, targeting specifically PIIBNP (QDVRQPG) and used in development of the assay. The specificity, sensitivity, 4-parameter fit and stability of the assay were tested. Levels of PIIBNP were quantified in human serum (0.6–2.2 nM), human amniotic fluid (163–188 nM) and sera from different animal species, e.g., fetal bovine serum (851–901 nM) with general good linearity (100% (SD 7.6) recovery) and good intra- and inter-assay variation (CV% < 10). Dose (0.1 to 100 ng/mL) and time (7, 14 and 21 days) dependent release of PIIBNP were evaluated in the conditioned medium from bovine cartilage explants (BEX) and human cartilage explants (HEX) upon stimulation with insulin-like growth factor (IGF-1), transforming growth factor (TGF)-β1 and fibroblastic growth factor-2 (FGF-2). TGF-β1 and IGF-1 in concentrations of 10–100 ng/mL significantly (p < 0.05) induced release of PIIBNP in BEX compared to conditions without treatment (WO). In HEX, IGF-1 100 ng/mL was able to induce a significant increase of PIIBNP after one week compared to WO. FGF-2 did not induce a PIIBNP release in our models. To our knowledge this is the first assay, which is able to specifically evaluate PIIBNP excretion. The Pro-C2 assay seems to provide a promising and novel marker of type II collagen formation.

Treatment of FGF‐2 on stem cells from inflamed dental pulp tissue from human deciduous teeth

The purposes of this study were to isolate and characterize stem cells from inflamed pulp tissue of human functional deciduous teeth (iSHFD) and to evaluate the influence of fibroblastic growth factor-2 (FGF-2) on the regenerative potential. We successfully isolated mesenchymal stem cells (MSCs) from the inflamed dental pulp tissue of human deciduous teeth and demonstrated that their regenerative potential could be enhanced by the application of FGF-2 (20 ng ml(-1)) during ex vivo expansion. Isolated stem cells expanded in FGF-2 were characterized using a colony-forming assay, proliferation, migration, in vitro differentiation, in vivo ectopic transplantation assay, and gene expression profiling. MSCs isolated from the inflamed pulp tissue of functional deciduous teeth potentially possess the qualities of those from human exfoliated deciduous teeth. FGF-2 applied to iSHFD during expansion enhanced the colony-forming efficiency of these cells, increased their proliferation and migration potential, and reduced their differentiation potential in vitro. However, the ectopic transplantation of iSHFD/FGF-2 in vivo increased the formation of dentin-like material. FGF-2 expansion of stem cells from inflamed pulp tissues of human deciduous teeth can be a good source of stem cells for future clinical applications and a novel way of using discarded inflamed tissues.

Role of sensory and motor intensity of electrical stimulation on fibroblastic growth factor-2 expression, inflammation, vascularization, and mechanical strength of full-thickness wounds

Electrical stimulation (ES) profoundly affects angiogenesis by modulating the production of angiogenic factors. We evaluated the effect of sensory (direct current, 600 microamperes) and motor (monophasic pulse current, 2.5 to 3 milliamperes, 300-microsecond pulse duration, 100 Hz) intensities of cathodal current on the release of fibroblastic growth factor-2 (FGF-2) at the wound site and also the biomechanical and histological properties of healed skin. Ninety-six male, Sprague-Dawley rats were randomly assigned into one control and two experimental groups. A full-thickness skin incision was made on the dorsal region of each animal. The experimental groups received 10 sessions of ES (sensory or motor) for 1 hour per day every other day. The results showed that FGF-2 levels in the sensory group were significantly greater than in the other groups on the third day. In the motor group, FGF-2 levels were significantly decreased compared with the control group. There were no significant differences between the normalized ultimate strength and stiffness in the groups, but they tended to be higher in the motor ES group. We conclude that the application of sensory ES during the early stage of wound healing may have a beneficial effect on wound healing by inducing the release of angiogenic factors and decreasing the duration of the inflammation phase.

Sciatic nerve grafting and inoculation of FGF-2 promotes improvement of motor behavior and fiber regrowth in rats with spinal cord transection

Failure of severed adult central nervous system (CNS) axons to regenerate could be attributed with a reduced intrinsic growing capacity. Severe spinal cord injury is frequently associated with a permanent loss of function because the surviving neurons are impaired to regrow their fibers and to reestablish functional contacts. Peripheral nerves are known as good substrate for bridging CNS trauma with neurotrophic factor addition. We evaluated whether fibroblastic growth factor 2 (FGF-2) placed in a gap promoted by complete transection of the spinal cord may increase the ability of sciatic nerve graft to enhance motor recovery and fibers regrow. We used a complete spinal cord transection model. Rats received a 4 mm-long gap at low thoracic level and were repaired with saline (control) or fragment of the sciatic nerve (Nerve) or FGF-2 was added to nerve fragment (Nerve+FGF-2) to the grafts immediately after complete transection. The hind limbs performance was evaluated weekly for 8 weeks by using motor behavior score (BBB) and sensorimotor tests-linked to the combined behavior score (CBS), which indicate the degree of the motor improvement and the percentage of functional deficit, respectively. Neuronal plasticity were evaluated at the epicenter of the injury using MAP-2 and GAP-43 expression. Spinal cord treatment with sciatic nerve and sciatic nerve plus FGF-2 allowed recovery of hind limb movements compared to control, manifested by significantly higher behavioral scores. Higher amounts of MAP-2 and GAP-43 immunoreactive fibers were found in the epicenter of the graft when FGF-2 was added. FGF-2 added to the nerve graft favored the motor recovery and fiber regrowth. Thus, these results encourage us to explore autologous transplantation as a novel and promising cell therapy for treatment of spinal cord lesion.

Rem2 GTPase maintains survival of human embryonic stem cells as well as enhancing reprogramming by regulating p53 and cyclin D1

Human pluripotent stem cells, such as embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), have the unique abilities of differentiation into any cell type of the organism (pluripotency) and indefinite self-renewal. Here, we show that the Rem2 GTPase, a suppressor of the p53 pathway, is up-regulated in hESCs and, by loss- and gain-of-function studies, that it is a major player in the maintenance of hESC self-renewal and pluripotency. We show that Rem2 mediates the fibroblastic growth factor 2 (FGF2) signaling pathway to maintain proliferation of hESCs. We demonstrate that Rem2 effects are mediated by suppressing the transcriptional activity of p53 and cyclin D(1) to maintain survival of hESCs. Importantly, Rem2 does this by preventing protein degradation during DNA damage. Given that Rem2 maintains hESCs, we also show that it is as efficient as c-Myc by enhancing reprogramming of human somatic cells into iPSCs eightfold. Rem2 does this by accelerating the cell cycle and protecting from apoptosis via its effects on cyclin D(1) expression/localization and suppression of p53 transcription. We show that the effects of Rem2 on cyclin D(1) are independent of p53 function. These results define the cell cycle and apoptosis as a rate-limiting step during the reprogramming phenomena. Our studies highlight the possibility of reprogramming somatic cells by imposing hESC-specific cell cycle features for making safer iPSCs for cell therapy use.

The modulation of platelet and endothelial cell adhesion to vascular graft materials by perlecan

Controlled neo-endothelialisation is critical to the patency of small diameter vascular grafts. Endothelialisation and platelet adhesion to purified endothelial cell-derived perlecan, the major heparan sulfate (HS) proteoglycan in basement membranes, were investigated using in vivo and in vitro assays. Expanded polytetrafluoroethylene (ePTFE) vascular grafts were coated with perlecan and tested in an ovine carotid interposition model for a period of 6 weeks and assessed using light and scanning microscopy. Enhanced endothelial cell growth and reduced platelet adhesion were observed on the perlecan coated grafts when compared to uncoated controls implanted in the same sheep ( n = 5). Perlecan was also found to stimulate endothelial cell proliferation in vitro over a period of 6 days in the presence of plasma proteins and fibroblastic growth factor 2 (FGF-2), however in the absence of FGF-2 endothelial cell growth could not be maintained during this period. Perlecan was found to be anti-adhesive for platelets, however after removal of the HS chains attached to perlecan, platelet adhesion and aggregation were supported. These results suggest a role for HS chains of perlecan in improving graft patency by selectively promoting endothelial cell proliferation while modulating platelet adhesion.

Chondrocyte proliferation in a new culture system

This study has aimed to study different culture systems that might stimulate an increase in cell proliferation of normal and osteoarthritis chondrocytes from articular cartilage in rat model. Three culture systems using chondrocytes embedded in alginate beads were tested: chondrocytes cultured in Dulbecco's modified Eagle's medium (DMEM) as control, a co-culture system consisting of a monolayer of de-differentiated chondrocytes as a source of mitotic factors, and an enriched medium containing culture medium obtained from a monolayer of chondrocytes and DMEM. Normal and osteoarthritis chondrocytes were stained with 5-carboxyfluorescein diacetate succinimidyl ester and were cultured in each of the three systems. After 5 days of culture cell, proliferation was detected by flow cytometry. Chondrocyte phenotype was confirmed by collagen type II and MMP-3 expression. To determine possible molecules released into the medium by the cultured chondrocyte monolayer and which would probably be involved in cell proliferation, a study of mRNA and expression of transforming growth factor-beta1 (TGF-beta1), fibroblastic growth factor-2 (FGF-2), epidermal growth factor (EGF), platelet derived growth factor-A (PDGF-A) and insulin-like growth factor-1 (IGF-1) proteins was conducted. Chondrocytes in the co-culture system or in enriched medium showed an increase in proliferation; only when osteoarthritis chondrocytes were cultured in enriched medium would they display a statistically significant increase in their proliferation rate and in their viability. When chondrocytes from the monolayer were analysed, differential mRNA expression of TGF-beta1 and IGF-1 was found during all passages, which suggests that these two growth factors might be involved in chondrocyte proliferation.

Improved Culture Expansion of Human Mesenchymal Stem Cells (MSCs) Using Fibroblastic Growth Factor-2 for the Treatment of Graft Versus Host Disease (GVHD).

Allogeneic hematopoietic stem cell (HSC) transplantation is an effective therapy for a number of diseases. However, graft-versus-host disease (GVHD) remains a significant obstacle to the successful outcome of this procedure. We have demonstrated in Phase I clinical trials that co-transplantation of culture expanded human MSCs during allogeneic HSC transplantation can facilitate engraftment without increasing the risk of GVHD. MSC have been shown to have immunomodulatory activity, and decrease T-cell interferon (IFN)-γ production. More recently, clinical studies have suggested that MSC infusion can also reduce the severity of GVHD. Based on these data, we have initiated a Phase I clinical trial (CWRU 3Y03) using allogeneic same-sibling donor MSC infusion of 1–6 × 106 culture expanded MSCs per kg for the treatment of acute or chronic GVHD of clinical grade II – IV after sibling donor HSC transplant. One of the main hurdles to overcome in MSC infusion protocols is the expansion of single donor MSCs to achieve the prescribed cell dose in a specified time frame. Here we report that the addition of recombinant human FGF-2 to the culture medium expedites and enhances MSC expansion capacity in normal adult donors cultured under clinically relevant conditions. In pre-clinical studies, MSCs from 13 normal donors (median age 28.5; range 21 – 40) were cultured in standard growth medium with or without FGF-2. The cells were expanded for up to 8 passages. MSCs expanded in the presence of FGF-2 exhibited shorter population doubling times and achieved a greater number of population doublings (31 ± 3) than those expanded in standard conditions (23 ± 2). These FGF-stimulated MSCs exhibited the same phenotype and immunomodulatory potential as MSCs grown in conventional medium. For each patient enrolled on CWRU 3Y03, donor MSCs were harvested, culture expanded and cryopreserved until indicated. Twenty-three culture expansions were attempted from 21 different donors (18 without FGF; 3 with FGF; median donor age 52, range 38 – 67). From the cultures grown in the absence of FGF, 11 donors were expanded to an infusion dose of 0.5 – 2.4 × 106 cells/kg (based on patient weight) with a mean of 161 ± 54 × 106 MSCs at harvest and a median cell expansion time of 41 days (range 23 – 66). Nine cultures failed to reach a minimum cell dose of 0.5 × 106 cells/kg during an 8-week culture period. The three MSC cultures grown in the presence of FGF -2 (R&D systems) were successful and reached infusion doses of 1.65 – 2.4 × 106 cells/kg. In these 3 cultures, the mean number of MSCs was 135 × 106 and the median day to harvest was 28 (range 27 – 41). The immunomodulatory potential of these three MSC preparations was tested in vitro in an IFN-γ EliSpot assay in which they inhibited IFN-γ production by 87.6 ± 5.4%. Cells from one donor that failed to expand in media without FGF-2 reached 171 × 106 (2.8 × 106/kg) MSCs in 27 days when MSCs from a second marrow harvest from the same donor were cultured in medium containing FGF-2, suggesting that FGF-2 supplementation may rescue a culture that may be otherwise unable to expand. Thus, FGF-2 can facilitate MSC culture expansion for clinical use while retaining their immunomodulatory function.

Hsulf-1 regulates growth and invasion of pancreatic cancer cells

Background: Hsulf-1 is a newly identified enzyme with arylsulphatase activity that can regulate the sulphation state of cell-surface heparan sulphate proteoglycans (HSPGs). In vitro overexpression of this enzyme in pancreatic...

Promotion of the intrinsic damage–repair response in articular cartilage by fibroblastic growth factor-2

To identify the effect of fibroblastic growth factor-2 (FGF-2) on the intrinsic damage-repair response in articular cartilage in vitro. Articular equine cartilage explants, without subchondral bone, had a single impact load of 500 g applied from a height of 2.5 cm. Explants were then cultured in 0, 12, 25, 50 or 100 ng/ml FGF-2 for up to 28 days. Unimpacted discs served as controls for each time-point. Histological and immunohistochemical techniques were used to quantify and characterise the response of putative chondrocyte progenitor cells (CPC) to damage and FGF-2 treatment. FGF-2 significantly accelerated the appearance and increased the numbers of de novo repair cells identified histologically at the cartilage surface. The response was affected by the dose of FGF-2. The repair cells were shown to be chondrocytes by their expression of collagen types II, IX/XI, but not of type I collagen. In addition, these cells, and those underlying the articular surface, were shown to be immunopositive for Notch-1 and PCNA, markers for proliferating cartilage progenitor cells. The results of this study indicate that, following single impact load, CPC can be stimulated in mature articular cartilage in vitro. These CPC and the cells arising from them appear to represent the cartilage's response to damage. The timing of the appearance of CPC and their overall numbers can be significantly increased by FGF-2, providing further evidence for an important role for FGF-2 in modulating cartilage repair. These results indicate that further study into the mechanisms of repair in mature cartilage using this in vitro model are vital in understanding the repair capacity of mature cartilage.

IL-6-type cytokines enhance epidermal growth factor-stimulated astrocyte proliferation.

Proliferating astrocytes are frequently observed in diseased and injured brains. These newly generated astrocytes are necessary to reestablish the barriers that isolate the CNS from the rest of the body; however, they also create a matrix that inhibits regeneration and remyelination. Therefore, it is important to understand the mechanisms that enable a terminally differentiated astrocyte to reenter the cell cycle. Ciliary neurotrophic factor (CNTF), interleukin-6 (IL-6), transforming growth factor-alpha (TGF-alpha), and fibroblastic growth factor-2 (FGF-2) are four cytokines that are rapidly elevated in damaged neural tissue. These cytokines also have been implicated in glial scar formation. We sought to determine whether IL-6 and CNTF stimulate astroglial proliferation alone or in combination with other mitogens. Intraparenchymal CNTF modestly increased the number of proliferating cell nuclear antigen (PCNA) and glial fibrillary acidic protein (GFAP) double positive astrocytes when introduced by stereotactic injection into the adult rat brain. When applied directly to highly enriched rat forebrain astrocyte cultures, neither CNTF nor IL-6-stimulated DNA synthesis. Therefore, they are not astroglial mitogens. However, both cytokines synergized with epidermal growth factor (EGF), increasing its mitogenicity by approximately twofold. Astrocytes that had been "aged" for at least 3 weeks in vitro became refractory to EGF; however, when these "aged" astrocytes were pretreated with either IL-6 or CNTF for as little as 2 h, they became competent to reenter the cell cycle upon exposure to EGF. These data suggest that IL-6 type cytokines, likely by activating STAT family transcription factors, induce the expression of signaling molecules that endow resting astrocytes with the competence to respond to mitogens and to reenter the cell cycle.

Vascular Smooth Muscle Cells Express the Transcriptional Corepressor NAB2 in Response to Injury

The early growth response 1 (Egr-1 or NGFI-A) gene product is a zinc finger protein transcription factor which has been implicated in the regulation of genes differentially expressed during the development of vascular disease. Egr-1 activity is regulated by alterations in the amount of protein, as well as protein-protein interactions with positive and negative transcriptional cofactors. NGFI-A-binding protein 2 (NAB2) is an example of a negative transcriptional cofactor capable of binding directly to Egr-1 and repressing Egr-1-mediated transcription. In this study, we show that NAB2 is rapidly and transiently expressed in vascular smooth muscle cells (VSMC) in response to the model agonist phorbol 12-myristate 13-acetate (PMA). This induction occurs at the protein as well as mRNA level, and the time course of induction trails closely behind that of Egr-1. NAB2 expression in VSMC is capable of inhibiting Egr-1 dependent gene expression in response to either PMA or fibroblastic growth factor-2 (FGF-2). In an in vivo model of mechanical arterial injury NAB2 levels also increase transiently in VSMC at a time when Egr-1 is elevated. It is possible that NAB2 is part of a negative-feedback mechanism which serves to down-regulate Egr-1-mediated gene transcription in injured VSMC.

Pathways of Egr-1-Mediated Gene Transcription in Vascular Biology

Vascular endothelium forms a continuous cellular interface between the circulating blood elements and the surrounding tissues. Endothelium forms a nonthrombogenic surface and selective permeability barrier capable of modulating vascular reactivity and blood flow. The integrity of the endothelium is fundamental for the maintenance of normal homeostasis. Injury to this lining results in dramatic changes in the functional characteristics of the endothelium, rendering it adhesive and prothrombotic. These changes may result from molecules inducibly expressed or simply secreted by injured endothelium. These initial events are correlated with subsequent inflammatatory and proliferative cellular changes associated with the development of vascular pathology.