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Jeremy D Pearson

Publications and source records attributed to Jeremy D Pearson.

17 recordsLinked to original sources
PubMed2006

CCN2 is necessary for adhesive responses to transforming growth factor-beta1 in embryonic fibroblasts.

CCN2 is induced by transforming growth factor-beta (TGFbeta) in fibroblasts and is overexpressed in connective tissue disease. CCN2 has been proposed to be a downstream mediator of TGFbeta action in fibroblasts; however, the role of CCN2 in regulating this process unclear. By using embryonic fibroblasts isolated from ccn2-/- mice, we showed that CCN2 is required for a subset of responses to TGFbeta. Affymetrix genome-wide expression profiling revealed that 942 transcripts were induced by TGFbeta greater than 2-fold in ccn2+/+ fibroblasts, of which 345 were not induced in ccn2-/- fibroblasts, including pro-adhesive and matrix remodeling genes. Whereas TGFbeta properly induced a generic Smad3-responsive promoter in ccn2-/- fibroblasts, TGFbeta-induced activation of focal adhesion kinase (FAK) and Akt was reduced in ccn2-/- fibroblasts. Emphasizing the importance of FAK and Akt activation in CCN2-dependent transcriptional responses to TGFbeta in fibroblasts, CCN2-dependent transcripts were not induced by TGFbeta in fak-/- fibroblasts and were reduced by wortmannin in wild-type fibroblasts. Akt1 overexpression in ccn2-/- fibroblasts rescued the TGFbeta-induced transcription of CCN2-dependent mRNA. Finally, induction of TGFbeta-induced fibroblast adhesion to fibronectin and type I collagen was significantly diminished in ccn2-/- fibroblasts. Thus in embryonic fibroblasts, CCN2 is a necessary cofactor required for TGFbeta to activate the adhesive FAK/Akt/phosphatidylinositol 3-kinase cascade, FAK/Akt-dependent genes, and adhesion to matrix.

Androstadienes↗
PubMed2006

Signaling pathways regulating intercellular adhesion molecule 1 expression by endothelin 1: comparison with interleukin-1beta in normal and scleroderma dermal fibroblasts.

OBJECTIVE: Endothelin 1 (ET-1) has been implicated in the pathogenesis of fibrotic and inflammatory diseases, including scleroderma. In addition to modulating vascular tone and extracellular matrix turnover, ET-1 up-regulates cell surface adhesion molecules including intercellular adhesion molecule 1 (ICAM-1), which is key to cell-cell and cell-matrix adhesion and leukocyte infiltration. This study was undertaken to delineate the signal transduction pathways utilized by ET-1 and compare them with those adopted by proinflammatory cytokine interleukin-1beta (IL-1beta) in normal and scleroderma dermal fibroblasts. METHODS: Protein expression induced by ET-1 and IL-1beta on normal dermal fibroblasts, with or without signaling inhibitors, was detected by enzyme-linked immunosorbent assay, while messenger RNA (mRNA) levels were analyzed by LightCycler polymerase chain reaction. Expression of protein kinase Cdelta (PKCdelta) and PKCepsilon protein in normal dermal fibroblasts and scleroderma dermal fibroblasts was determined by Western blotting, and PKCepsilon involvement in ET-1 signaling was confirmed through transfection of an ICAM-1 promoter construct into murine PKCepsilon-/- fibroblasts. NF-kappaB activation was confirmed via electrophoretic mobility supershift assay, and analysis of the ICAM-1 promoter region was achieved via transfection of deletion constructs into human dermal fibroblasts. RESULTS: In normal dermal fibroblasts, ET-1 induced ICAM-1 mRNA and surface protein expression in a dose- and time-dependent manner via both receptor subtypes, ET(A) and ET(B); antagonism of both abolished the ET-1 response. MEK was involved in the signaling cascade, but phosphatidylinositol 3-kinase and p38 MAPK were not. Key to the cascade was activation of NF-kappaB, achieved by ligation of either receptor subtype. PKCepsilon activation led to downstream activation of MEK and, in part, NF-kappaB. IL-1beta signaling required NF-kappaB and MEK activation, along with activation of PKCdelta. ET-1 and IL-1beta each utilized the same ICAM-1 promoter region and the same NF-kappaB site at -157 bp. Responses to ET-1 and IL-1beta differed in scleroderma dermal fibroblasts, with ET-1 sensitivity decreasing and IL-1beta responses remaining intact. Expression of PKCepsilon and PKCdelta in scleroderma dermal fibroblasts was also altered. CONCLUSION: The findings of this study indicate that differences in sensitivity to ET-1 and IL-1beta in scleroderma dermal fibroblasts may be explained by altered expression of the PKC isoforms and cytokine receptors.

Cell Line↗
PubMed2006

Nitric oxide reduces adenosine transporter ENT1 gene (SLC29A1) promoter activity in human fetal endothelium from gestational diabetes.

Human umbilical vein endothelial cells (HUVEC) from gestational diabetes exhibit reduced adenosine uptake and increased nitric oxide (NO) synthesis. Adenosine transport via human equilibrative nucleoside transporters 1 (hENT1) is reduced by NO by unknown mechanisms in HUVEC. We examined whether gestational diabetes-reduced adenosine transport results from lower hENT1 gene (SLC29A1) expression. HUVEC from gestational diabetes exhibit reduced SLC29A1 promoter activity when transfected with pGL3-hENT1(-2154) compared with pGL3-hENT1(-1114) constructs, an effect blocked by N(G)-nitro-L-arginine methyl ester (L-NAME, NOS inhibitor), but unaltered by S-nitroso-N-acetyl-L,D-penicillamine (SNAP, NO donor). In cells from gestational diabetes transfected with pGL3-hENT1(-2154), L-NAME increased, but SNAP did not alter promoter activity and hENT1 expression. However, in cells from normal pregnancies L-NAME increased, but SNAP reduced promoter activity and hENT1 expression. Adenovirus-silenced eNOS expression increased hENT1 expression and activity in cells from normal or gestational diabetic pregnancies. Thus, reduced adenosine transport may result from downregulation of SLC29A1 expression by NO in HUVEC from gestational diabetes. These findings explain the accumulation of extracellular adenosine detected in cultures of HUVEC from gestational diabetes. In addition, fetal endothelial dysfunction could be involved in the abnormal fetal development and growth seen in gestational diabetes.

Adenosine↗
PubMed2006

Constitutive ALK5-independent c-Jun N-terminal kinase activation contributes to endothelin-1 overexpression in pulmonary fibrosis: evidence of an autocrine endothelin loop operating through the endothelin A and B receptors.

The signal transduction mechanisms generating pathological fibrosis are almost wholly unknown. Endothelin-1 (ET-1), which is up-regulated during tissue repair and fibrosis, induces lung fibroblasts to produce and contract extracellular matrix. Lung fibroblasts isolated from scleroderma patients with chronic pulmonary fibrosis produce elevated levels of ET-1, which contribute to the persistent fibrotic phenotype of these cells. Transforming growth factor beta (TGF-beta) induces fibroblasts to produce and contract matrix. In this report, we show that TGF-beta induces ET-1 in normal and fibrotic lung fibroblasts in a Smad-independent ALK5/c-Jun N-terminal kinase (JNK)/Ap-1-dependent fashion. ET-1 induces JNK through TAK1. Fibrotic lung fibroblasts display constitutive JNK activation, which was reduced by the dual ETA/ETB receptor inhibitor, bosentan, providing evidence of an autocrine endothelin loop. Thus, ET-1 and TGF-beta are likely to cooperate in the pathogenesis of pulmonary fibrosis. As elevated JNK activation in fibrotic lung fibroblasts contributes to the persistence of the myofibroblast phenotype in pulmonary fibrosis by promoting an autocrine ET-1 loop, targeting the ETA and ETB receptors or constitutive JNK activation by fibrotic lung fibroblasts is likely to be of benefit in combating chronic pulmonary fibrosis.

Actins↗
PubMed2004

Rate of transport of l-arginine is independent of the expression of inducible nitric oxide synthase in HEK 293 cells.

Expression of inducible nitric oxide synthase (iNOS) is generally accompanied by a parallel upregulation in l-arginine transport which is dependent, at least in part, on the synthesis of new carrier proteins. It is not clear however whether the induction of iNOS and its subsequent utilisation of l-arginine for NO synthesis contribute to the enhancement in l-arginine transport rates observed following induction of cells with pro-inflammatory mediators. To address this issue, we have transfected an iNOS construct in a pEGFP-N1 vector into HEK-293 cells and investigated the effects this has on l-arginine transport. The expression of iNOS through transfection resulted in the production of significant quantities of NO as detected by the standard Griess assay. Under these conditions, the transport of l-arginine was found to be unaltered, with rate of uptake being comparable in both transfected and non-transfected cells. Characterisation of the transporter(s) involved with uptake of l-arginine revealed features characteristic of the classical cationic amino acid transport system y(+). Further analysis of the expression profile of the cationic amino acid transporter (CAT) involved revealed the presence of transcripts for CAT-1 and CAT-2B. These data demonstrate that iNOS activity does not drive or enhance l-arginine transport despite the fact that HEK-293 cells transport l-arginine via the CATs, including CAT-2B which is thought to be critical for supply of substrate to iNOS.

Amino Acid Sequence↗
PubMed2004

Gene expression profiling reveals novel TGFbeta targets in adult lung fibroblasts.

BACKGROUND: Transforming growth factor beta (TGFbeta), a multifunctional cytokine, plays a crucial role in the accumulation of extracellular matrix components in lung fibrosis, where lung fibroblasts are considered to play a major role. Even though the effects of TGFbeta on the gene expression of several proteins have been investigated in several lung fibroblast cell lines, the global pattern of response to this cytokine in adult lung fibroblasts is still unknown. METHODS: We used Affymetrix oligonucleotide microarrays U95v2, containing approximately 12,000 human genes, to study the transcriptional profile in response to a four hour treatment with TGFbeta in control lung fibroblasts and in fibroblasts from patients with idiopathic and scleroderma-associated pulmonary fibrosis. A combination of the Affymetrix change algorithm (Microarray Suite 5) and of analysis of variance models was used to identify TGFbeta-regulated genes. Additional criteria were an average up- or down- regulation of at least two fold. RESULTS: Exposure of fibroblasts to TGFbeta had a profound impact on gene expression, resulting in regulation of 129 transcripts. We focused on genes not previously found to be regulated by TGFbeta in lung fibroblasts or other cell types, including nuclear co-repressor 2, SMAD specific E3 ubiquitin protein ligase 2 (SMURF2), bone morphogenetic protein 4, and angiotensin II receptor type 1 (AGTR1), and confirmed the microarray results by real time-PCR. Western Blotting confirmed induction at the protein level of AGTR1, the most highly induced gene in both control and fibrotic lung fibroblasts among genes encoding for signal transduction molecules. Upregulation of AGTR1 occurred through the MKK1/MKK2 signalling pathway. Immunohistochemical staining showed AGTR1 expression by lung fibroblasts in fibroblastic foci within biopsies of idiopathic pulmonary fibrosis. CONCLUSIONS: This study identifies several novel TGFbeta targets in lung fibroblasts, and confirms with independent methods the induction of angiotensin II receptor type 1, underlining a potential role for angiotensin II receptor 1 antagonism in the treatment of lung fibrosis.

Cells, Cultured↗
PubMed2004

CCN2 (connective tissue growth factor) promotes fibroblast adhesion to fibronectin.

In vivo, CCN2 (connective tissue growth factor) promotes angiogenesis, osteogenesis, tissue repair, and fibrosis, through largely unknown mechanisms. In vitro, CCN2 promotes cell adhesion in a variety of systems via integrins and heparin sulfate proteoglycans (HSPGs). However, the physiological relevance of CCN2-mediated cell adhesion is unknown. Here, we find that HSPGs and the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase cascade are required for adult human dermal fibroblasts to adhere to CCN2. Endogenous CCN2 directly binds fibronectin and the fibronectin receptors integrins alpha4 beta1 and alpha5 and syndecan 4. Using Ccn2-/- mouse embryonic fibroblasts, we show that loss of endogenous CCN2 results in impaired spreading on fibronectin, delayed alpha-smooth muscle actin stress fiber formation, and reduced ERK and focal adhesion kinase phosphorylation. These results suggest that a physiological role of CCN2 is to potentiate the ability of fibroblasts to spread on fibronectin, which may be important in modulating fibroblast adhesion to the provisional matrix during tissue development and wound healing. These results are consistent with the notion that a principal function of CCN2 is to modulate receptor/ligand interactions in vivo.

Animals↗
PubMed2004

Circulating humoral factors and endothelial progenitor cells in patients with differing coronary collateral support.

BACKGROUND: The mechanisms underlying the variation in collateral formation between patients, even with similar patterns of coronary artery disease, remain unclear. This study investigates whether circulating humoral or cellular factors can provide an insight into this variation. METHODS AND RESULTS: Thirty patients with isolated left anterior descending coronary artery disease underwent percutaneous coronary intervention with collateral flow index (CFI) determined using a pressure wire. Patients with inadequate (CFI <0.25) compared with those with adequate (CFI > or =0.25) collateral support had, or tended to have, lower concentrations of coronary sinus growth factors and plasma exerting a weaker effect on endothelial cell migration and angiogenesis in vitro. However, there was an inverse correlation between serum mitogenicity and CFI (r=-0.61, P<0.01). No significant differences were detected between the 2 groups in plasma levels of total vascular endothelial growth factor, vascular endothelial growth factor165, or placental growth factor. There was a strong positive correlation between numbers of CD34/CD133-positive circulating hemopoietic precursor cells and CFI (r=0.75, P<0.001). In patients with inadequate, compared with those with adequate, CFI, the numbers of differentiated endothelial progenitor cells (EPCs) appearing in the circulation and in culture were significantly reduced by 75% (P<0.05) and 70% (P<0.05), respectively. CONCLUSIONS: In this study, inadequate coronary collateral development is associated with reduced numbers of circulating EPCs and impaired chemotactic and proangiogenic but not mitogenic activity. These findings are consistent with current efforts to enhance collateral formation by augmentation of circulating EPCs.

Aged↗
PubMed2004

Cell signalling-mediating insulin increase of mRNA expression for cationic amino acid transporters-1 and -2 and membrane hyperpolarization in human umbilical vein endothelial cells.

Insulin induces vasodilatation in human subjects and increases L-arginine transport and NO synthesis in human umbilical vein endothelial cells (HUVEC). Cell signalling events associated with insulin effects on activity and mRNA expression of the human cationic amino acid transporters 1 (hCAT-1) and 2B (hCAT-2B) are unknown. L-arginine transport and eNOS activity were determined in HUVEC exposed to insulin. mRNA levels for hCAT-1, hCAT-2B and eNOS were quantitated by real time RT-PCR and endothelial NO synthase (eNOS) protein was identified by Western blot analysis. Intracellular Ca2+, L-arginine and L-citrulline levels, L-[3H]citrulline formation from L-[(3)H]arginine, cGMP formation, nitrite level, ATP release and membrane potential were determined. Insulin increased L-arginine transport and the mRNA levels for hCAT-1 and hCAT-2B and eNOS expression and activity. Insulin also induced membrane hyperpolarization and increased intracellular Ca2+, L-[3H]citrulline, cGMP and nitrite formation. Insulin-mediated stimulation of the L-arginine/NO pathway is thus associated with increased hCAT-1 and hCAT-2B mRNA, and eNOS expression, via mechanisms involving membrane hyperpolarization, mitogen-activated protein kinases p42 and p44, phosphatidylinositol 3-kinase, NO and protein kinase C. We have characterized a cell signalling pathway by which hyperinsulinaemia could lead to vasodilatation in human subjects, and which could have implications in patients in whom plasma insulin levels are altered, such as in diabetes mellitus.

Adenosine Triphosphate↗
PubMed2004

Endothelin-1 promotes myofibroblast induction through the ETA receptor via a rac/phosphoinositide 3-kinase/Akt-dependent pathway and is essential for the enhanced contractile phenotype of fibrotic fibroblasts.

The endothelins are a family of endothelium-derived peptides that possess a variety of functions, including vasoconstriction. Endothelin-1 (ET-1) is up-regulated during tissue repair and promotes myofibroblast contraction and migration, hence contributing to matrix remodeling during tissue repair. Here, we show that addition of ET-1 to normal lung fibroblasts induces expression of proteins that contribute to a contractile phenotype, including alpha-smooth muscle actin (alpha-SMA), ezrin, moesin, and paxillin. We confirm that ET-1 enhances the ability of lung fibroblasts to contract extracellular matrix, a function essential for tissue repair, through induction of de novo protein synthesis. Blockade of the Akt/phosphoinositide 3-kinase (PI3-kinase) pathway with LY294002 and wortmannin prevents the ability of ET-1 to induce alpha-SMA, ezrin, paxillin, and moesin and to promote matrix contraction. Dominant negative rac and Akt blocked the ability of ET-1 to promote formation of alpha-SMA stress fibers. Using specific ET-1 receptor inhibitors, we show that ET-1 induces collagen matrix contraction through the ETA, but not the ETB, receptor. Relative to normal pulmonary fibroblasts, fibroblasts cultured from scars of patients with the fibrotic disease systemic sclerosis (scleroderma) show enhanced ET-1 expression and binding. Systemic sclerosis lung fibroblasts show increased ability to contract a collagen matrix and elevated expression of the procontractile proteins alpha-SMA, ezrin, paxillin, and moesin, which are greatly reduced by antagonizing endogenous ET-1 signaling. Thus, blocking ET-1 or the PI3-kinase/Akt cascades might be beneficial in reducing scar formation in pulmonary fibrosis.

Cell Membrane↗
PubMed2004

Endothelin-1 induces expression of matrix-associated genes in lung fibroblasts through MEK/ERK.

The endothelins are a family of endothelium-derived peptides that possess a variety of biological activities, including potent vasoconstriction. Endothelin-1 (ET-1) is up-regulated during tissue repair and pulmonary fibrosis. Here, we use genome-wide expression array analysis to show that the addition of ET-1 (100 nm, 4 h) to normal lung fibroblasts directly induces expression of matrix and matrix-associated genes, including the profibrotic protein CCN2 (connective tissue growth factor, or CTGF). ET-1 induces the MEK/ERK MAP kinase pathway in fibroblasts. Blockade of the MEK/ERK kinase pathway with U0126 abrogates the ability of ET-1 to induce expression of matrix and matrix-associated mRNAs and the CCN2 protein. The CCN2 promoter possesses an ET-1 response element, which maps to the previously identified basal control element-1 (BCE-1) site. Our results suggest that ET-1 induces a program of matrix synthesis in lung fibroblasts and that ET-1 may play a key role in connective tissue deposition during wound repair and in pulmonary fibrosis.

Endothelin-1↗
PubMed2003

Role of L-citrulline transport in nitric oxide synthesis in rat aortic smooth muscle cells activated with LPS and interferon-gamma.

(1) l-citrulline, a coproduct of nitric oxide synthase (NOS)-catalysed metabolism of l-arginine to nitric oxide (NO), is an important intermediate of the urea cycle and a precursor for l-arginine biosynthesis in vascular cells. (2) In the present study, we have examined the characteristics of l-citrulline transport, regulation by lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) and the ability of l-citrulline to sustain NO synthesis in rat cultured aortic smooth muscle cells. (3) l-citrulline transport was saturable with an apparent Km=1.6+/-0.2 mm and Vmax=5.9+/-0.6 pmol microg-1 protein min-1. Transport was pH-insensitive, partially Na+-dependent and markedly inhibited by substrates selective for amino-acid transport systems L and N but not by l-arginine or substrates for systems A, ASC, xc- or XAG. Moreover, transport was not altered in cells treated with LPS (100 microg ml-1) and IFN-gamma (50 U ml-1) for 0-24 h. (4) Unlike l-arginine, l-citrulline could not sustain maximal NO production in cells expressing iNOS. (5) Our findings provide the first evidence in vascular smooth muscle cells that l-citrulline transport is mediated via a low-affinity carrier with characteristics resembling systems L and N. Moreover, in l-arginine-deprived rat aortic smooth muscle cells, l-citrulline cannot sustain maximal NO release via iNOS.

Animals↗
PubMed2003

Rapid stimulation of L-arginine transport by D-glucose involves p42/44(mapk) and nitric oxide in human umbilical vein endothelium.

D-glucose infusion and gestational diabetes induce vasodilatation in humans and increase L-arginine transport and nitric oxide (NO) synthesis in human umbilical vein endothelial cells. High D-glucose (25 mmol/L, 2 minutes) induced membrane hyperpolarization and an increase of L-arginine transport (V(max) 6.1+/-0.7 versus 4.4+/-0.1 pmol/ microg protein per minute) with no change in transport affinity (K(m) 105+/-9 versus 111+/-16 micromol/L). L-[3H]citrulline formation and intracellular cGMP, but not intracellular Ca2+, were increased by high D-glucose. The effects of D-glucose were mimicked by levcromakalim (ATP-sensitive K+ channel blocker), paralleled by p42/p44(mapk) and Ser(1177)-endothelial NO synthase phosphorylation, inhibited by N(G)-nitro-L-arginine methyl ester (L-NAME; NO synthesis inhibitor), glibenclamide (ATP-sensitive K+ channel blocker), KT-5823 (protein kinase G inhibitor), PD-98059 (mitogen-activated protein kinase kinase 1/2 inhibitor), and wortmannin (phosphatidylinositol 3-kinase inhibitor), but they were unaffected by calphostin C (protein kinase C inhibitor). Elevated D-glucose did not alter superoxide dismutase activity. Our findings demonstrate that the human fetal endothelial L-arginine/NO signaling pathway is rapidly activated by elevated D-glucose via NO and p42/44(mapk). This could be determinant in pathologies in which rapid fluctuations of plasma D-glucose may occur and may underlie the reported vasodilatation in early stages of diabetes mellitus.

Amino Acid Transport Systems, Basic↗
PubMed2001

HIF-1 is expressed in normoxic tissue and displays an organ-specific regulation under systemic hypoxia.

Adaptation to hypoxia is regulated by hypoxia-inducible factor 1 (HIF-1), a heterodimeric transcription factor consisting of an oxygen-regulated alpha subunit and a constitutively expressed beta subunit. Although HIF-1 is regulated mainly by oxygen tension through the oxygen-dependent degradation of its alpha subunit, in vitro it can also be modulated by cytokines, hormones and genetic alterations. To investigate HIF-1 activation in vivo, we determined the spatial and temporal distribution of HIF-1 in healthy mice subjected to varying fractions of inspiratory oxygen. Immunohistochemical examination of brain, kidney, liver, heart, and skeletal muscle revealed that HIF-1alpha is present in mice kept under normoxic conditions and is further increased in response to systemic hypoxia. Moreover, immunoblot analysis showed that the kinetics of HIF-1alpha expression varies among different organs. In liver and kidney, HIF-1alpha reaches maximal levels after 1 h and gradually decreases to baseline levels after 4 h of continuous hypoxia. In the brain, however, HIF-1alpha is maximally expressed after 5 h and declines to basal levels by 12 h. Whereas HIF-1beta is constitutively expressed in brain and kidney nuclear extracts, its hepatic expression increases concomitantly with HIF-1alpha. Overall, HIF-1alpha expression in normoxic mice suggests that HIF-1 has an important role in tissue homeostasis.

Animals↗