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J L Swain

Publications and source records attributed to J L Swain.

At least 19 recordsLinked to original sources
PubMed2000

Maintenance of vascular integrity in the embryo requires signaling through the fibroblast growth factor receptor.

Basic fibroblast growth factor (FGF)-2 is important for vessel formation and/or maintenance of vascular integrity in the embryo. FGF signaling may be mediated through transmembrane tyrosine kinase receptors or directly through intracellular pathways that do not involve receptor activation. To determine the role of receptor-mediated signaling in endothelial cells, an adenovirus encoding truncated FGF receptor (FGFR)-1, under the control of the cytomegalovirus promoter, was expressed in endothelial cells. FGF signaling was impaired, as indicated by inhibition of MAPK phosphorylation. Functional consequences included inhibition of endothelial cell migration and induction of apoptosis. To address the role of endothelial FGFR signaling in vascular development, recombinant adenovirus encoding a dominant-negative FGFR was injected into the sinus venosus of embryonic day 9.0 cultured mouse embryos. Previous studies demonstrated that transgenes delivered via adenovirus, under the control of the cytomegalovirus promoter, are expressed selectively in the developing vasculature. Embryos expressing a control adenovirus developed normally, whereas those expressing the FGFR-1 mutant exhibited abnormal embryonic and extra-embryonic vascular development. These data demonstrate that FGF, by signaling through the FGFR, plays a pivotal role in the development and maintenance of a mature vascular network in the embryo.

Animals↗
PubMed2000

Inhibition of angiogenesis by a mouse sprouty protein.

Sprouty negatively modulates branching morphogenesis in the Drosophila tracheal system. To address the role of mammalian Sprouty homologues in angiogenesis, another form of branching morphogenesis, a recombinant adenovirus engineered to express murine Sprouty-4 selectively in endothelial cells, was injected into the sinus venosus of embryonic day 9.0 cultured mouse embryos. Sprouty-4 expression inhibited branching and sprouting of small vessels, resulting in abnormal embryonic development. In vitro, Sprouty-4 inhibited fibroblast growth factor and vascular endothelial cell growth factor-mediated cell proliferation and migration and prevented basic fibroblast growth factor and vascular endothelial cell growth factor-induced MAPK phosphorylation in endothelial cells, indicating inhibition of tyrosine kinase-mediated signaling pathways. The ability of constitutively activated mutant Ras(L61) to rescue Sprouty-4 inhibition of MAPK phosphorylation suggests that Sprouty inhibits receptor tyrosine kinase signaling upstream of Ras. Thus, Sprouty may regulate angiogenesis in normal and disease processes by modulating signaling by endothelial tyrosine kinases.

Animals↗
PubMed1999

FGF receptor availability regulates skeletal myogenesis.

Fibroblast growth factors (FGFs) and their receptors are critical participants in embryonic development, including the genesis of skeletal, cardiac, and smooth muscle. FGF signaling is mediated through interactions between multiple FGF ligands and transmembrane tyrosine kinase receptors, resulting in activation of a number of signal transduction pathways. Skeletal myocytes express FGF ligands and receptors in a coordinated fashion, suggesting that these molecules participate in autocrine signaling in the myocyte. Endogenously produced FGF has been shown to inhibit myogenesis, but the role of FGF receptor availability in directing myocyte proliferation and differentiation has not been established. To determine the contribution of receptor availability to the regulation of myogenesis, receptor availability was either increased by expressing a full-length FGF receptor-1 or decreased by expressing a truncated FGF receptor-1 in cultured skeletal myocytes. Constitutive expression of a full-length FGF receptor-1 increased myocyte proliferation and delayed differentiation. Conversely, a reduction in functional FGF receptor signaling by expression of a truncated FGF receptor-1 decreased proliferation and enhanced differentiation of myocytes. These data demonstrate that FGF receptor availability plays a critical regulatory role in skeletal myogenesis.

Animals↗
PubMed1999

Common variant in AMPD1 gene predicts improved clinical outcome in patients with heart failure.

BACKGROUND: This study was undertaken to identify gene(s) that may be associated with improved clinical outcome in patients with congestive heart failure (CHF). The adenosine monophosphate deaminase locus (AMPD1) was selected for study. We hypothesized that inheritance of the mutant AMPD1 allele is associated with increased probability of survival without cardiac transplantation in patients with CHF. METHODS AND RESULTS: AMPD1 genotype was determined in 132 patients with advanced CHF and 91 control reference subjects by use of a polymerase chain reaction-based, allele-specific oligonucleotide detection assay. In patients with CHF, those heterozygous (n=20) or homozygous (n=1) for the mutant AMPD1 allele (AMPD1 +/- or -/-, respectively) experienced a significantly longer duration of heart failure symptoms before referral for transplantation evaluation than CHF patients homozygous for the wild-type allele (AMPD1 +/+; n=111; 7.6+/-6.5 versus 3.2+/-3.6 years; P<0.001). The OR of surviving without cardiac transplantation >/=5 years after initial hospitalization for CHF symptoms was 8.6 times greater (95% CI: 3.05, 23.87) in those patients carrying >/=1 mutant AMPD1 allele than in those carrying 2 wild-type AMPD1 +/+ alleles. CONCLUSIONS: After the onset of CHF symptoms, the mutant AMPD1 allele is associated with prolonged probability of survival without cardiac transplantation. The mechanism by which the presence of the mutant AMPD1 allele may modify the clinical phenotype of heart failure remains to be determined.

AMP Deaminase↗
PubMed1999

Efficient transmural cardiac gene transfer by intrapericardial injection in neonatal mice.

An efficient cardiac gene transfer technique in murine models would greatly facilitate the elucidation of the pathophysiology of cardiomyopathies and the development of genetic therapies. Direct myocardial injection or catheter-based intracoronary infusion is not easily achievable in mice and resultant transgene expression is often limited in distribution. A replication-defective, recombinant adenovirus encoding luciferase (5x10(9)pfu) or lacZ (4-5x10(10)particles/animal) was injected percutaneously into the pericardial cavity of 4-5 day old mice. Chemiluminescence assay for luciferase activity at 3 days post-injection revealed the highest activity in the heart (heart=288+/-110, lungs=19+/-5, liver=11+/-5 ng/gm tissue, n=11). X-gal staining of cryostat sections demonstrated widespread transmural lacZ expression in the left ventricle, interventricular septum, right ventricle, and atrial appendages, and the average fractional area of X-gal staining in a left ventricle was 66+/-16% (range 40-92%, n=21 sections). However, the long-term survival of these mice was compromised. Reduction in the injectate volume by 50% significantly improved survival but concurrently reduced lacZ expression. Significant lacZ expression was observed in the right ventricle and interventricular septum but left ventricular expression was predominantly epicardial, with variable myocardial penetration. At 2 months post-injection, lacZ expression persisted only in atrial tissues, pulmonary veins, and great vessels. Despite lack of persistent transgene expression in ventricular tissues, the high degree of transgene expression achieved may be sufficient to allow evaluation of short-term effects of specific genetic manipulations in the heart.

Adenoviridae↗
PubMed1998

Adenoviral-mediated expression of antisense RNA to fibroblast growth factors disrupts murine vascular development.

Fibroblast growth factors (FGFs) are expressed in the developing embryo and are postulated to regulate embryonic and vascular growth. The goal of this study was to elucidate the role of basic fibroblast growth factor (FGF-2) in early murine embryonic cardiovascular development in the mouse embryo. Gestation day 7.5 embryos were harvested and placed in culture, and 12 hr later replication-defective adenovirus (0.5 x 10(6) plaque forming units) encoding either beta-galactosidase or antisense FGF-2 RNA was injected into the sinus venosus of the cultured embryos. Embryos receiving only replication-defective adenovirus expressing the beta-galactosidase gene continued to develop normally over the next 12 hr. In contrast, those receiving adenovirus encoding antisense FGF-2 RNA displayed marked morphogenetic abnormalities, including cessation of growth and abnormal yolk sac vascular development, even though the embryonic hearts continued to beat. Abnormal development of the yolk sac vasculature was confirmed by microangiography and by histologic examination. Coinjection of virus carrying FGF-2 cDNA in the sense orientation reversed the effects of antisense FGF-2 RNA expression. These results confirm the efficacy of the replication-defective adenovirus for targeting gene expression to the developing vasculature and provide evidence for a critical role of FGF in the normal vascular assembly in the early embryo. Cessation of embryonic growth on expression of antisense FGF-2 RNA was most likely attributable to failure of efficient circulation of the early embryonic blood cells from the yolk sac into the embryo.

Adenoviridae↗
PubMed1998

Autocrine FGF signaling is required for vascular smooth muscle cell survival in vitro.

Expression of both basic fibroblast growth factor (bFGF) and FGF receptors (FGFR) by vascular smooth muscle cells suggests that autocrine FGF signaling mechanisms may have important functions. Inhibition of smooth muscle cell bFGF expression provokes apoptosis, suggesting that endogenous bFGF generates an anti-apoptotic signal. The purpose of this study was to determine whether the survival function of endogenous bFGF requires signaling through FGFR. A recombinant adenovirus encoding a truncated murine FGFR-1 lacking the kinase domain (DN-FGFR) efficiently expressed the transgene in cultured rat aortic smooth muscle cells. The truncated receptor acted in a dominant negative fashion to effectively prevent receptor-mediated signaling, assessed by phosphorylation of p42/p44 MAP kinase. Expression of DN-FGFR provoked apoptosis of SMC in a dose-dependent fashion that was insensitive to recombinant bFGF but could be rescued by platelet derived growth factor or epidermal growth factor. Heterologous growth factor rescue was inhibited by PD98059, an inhibitor of MEK (MAP kinase-kinase). These data demonstrate that inhibition of FGF receptor activation results in apoptosis and suggest that an intact autocrine FGF signaling loop is required for vascular smooth muscle cell survival in vitro. These findings also implicate the Ras/Raf/MEK/MAP kinase cascade in generating or sustaining the survival signal. The functional significance of an autocrine FGF signaling loop in non-transformed cells has important implications for cardiovascular development, remodeling and disease.

Adenoviridae↗
PubMed1997

In utero cardiac gene transfer via intraplacental delivery of recombinant adenovirus.

BACKGROUND: The relationship among the maternal, placental, and uniquely shunted embryonic circulation was explored to provide access to the embryonic cardiovascular system in utero. Manipulation of gene expression in the developing heart would be particularly useful for studying the effects of altered gene expression on cardiac development and in the etiology of congenital cardiac anomalies. METHODS AND RESULTS: Dye studies demonstrated that intraplacental injection allows direct access to the embryonic cardiac and systemic circulation. To evaluate the efficacy of cardiac gene transfer using this approach, replication-deficient recombinant adenoviral vectors encoding luciferase or beta-galactosidase as reporter genes were injected intraplacentally into embryonic day (E)12.5 murine embryos, an age at which the mass of the heart was observed to be large compared with other organs. Embryos were assayed for transgene expression at E15.5 and at birth. Survival rates at these times were similar among vector-injected and control groups. At E15.5 and at birth, luciferase activity within the heart was 9- and 23-fold higher, respectively, than in the remainder of the embryo, although levels of expression were generally lower at birth than during embryonic life. Beta-galactosidase expression was observed within all regions of the embryonic heart and was localized to approximately 15% of atrial and ventricular cells. CONCLUSIONS: Intraplacental delivery of adenovirus at embryonic day 12.5 results in somatic gene transfer to the murine embryonic heart, which persists at least until birth. The combination of intraplacental injection to directly access the fetal coronary circulation and injection at E12.5 when the mass of the heart is large compared with other organs results in transgene expression in cardiac cells. Intraplacental injections early in embryonic life may thus be useful to study the effects of temporal manipulation of gene expression on cardiac development and disease.

Adenoviridae↗
PubMed1997

Antisense basic fibroblast growth factor gene transfer reduces neointimal thickening after arterial injury.

PURPOSE: To determine whether synthesis of endogenous basic fibroblast growth factor (bFGF) after arterial injury is critical to the intimal thickening response, intraluminal adenoviral gene transfer of an antisense bFGF (Ad.ASbFGF) transgene was used to inhibit the subsequent synthesis of bFGF protein after injury. METHODS: Sprague-Dawley rats underwent balloon catheter carotid artery injury and in vivo gene transfer. Isolated segments of rat common carotid artery were infected with an adenoviral vector encoding an antisense bFGF transcript at concentrations of 2 x 10(9), 1 x 10(10), or 1 x 10(11) pfu/ml. Control rats were treated with either a control adenovirus encoding the beta-galactosidase gene, (Ad.lacZ), at 1 x 10(10), or 1 x 10(11) pfu/ml, or phosphate-buffered saline solution (vehicle). Two weeks after injury the rats were killed and perfusion-fixed. Cross-sectional areas of the carotid arterial intima and media were measured by planimetry, and the intima/media ratio (I/M) was calculated for each vessel. RESULTS: The mean I/M for each Ad.ASbFGF group and controls were compared and the significance assessed by analysis of variance. At two weeks after injury, the highest dose of Ad.ASbFGF, 1 x 10(11) pfu/ml, resulted in a near total inhibition of thickening (I/M = 0.14 +/- 0.04, mean +/- SEM) when compared with phosphate-buffered saline solution alone (I/M = 0.99 +/- 0.07), or Ad.lacZ 1 x 10(10) pfu/ml (I/M = 1.01 +/- 0.10) control treatments (p < 0.01). A tenfold lower dose of Ad.ASbFGF, 1 x 10(10) pfu/ml, also caused significant reduction in intimal thickening (I/M = 0.39 +/- 0.07, p < 0.01). Treatment with 2 x 10(9) pfu/ml Ad.ASbFGF did not significantly limit intimal thickening (I/M = 0.72 +/- 0.12). CONCLUSIONS: Inhibition of bFGF synthesis in vivo using an antisense RNA strategy significantly inhibits intimal thickening after arterial balloon injury. This study suggests that continued bFGF synthesis contributes to intimal thickening after arterial injury, and that antisense bFGF may represent an effective strategy in limiting restenosis after angioplasty.

Adenoviruses, Human↗
PubMed1997

Judith L. Swain.

Explore the source record for details and available documents.

Academic Medical Centers↗
PubMed1994

Myogenic differentiation triggered by antisense acidic fibroblast growth factor RNA.

Acidic fibroblast growth factor (FGF) and related family members regulate differentiation in organisms as diverse as Xenopus laevis and mammals. We utilized a well-characterized model of myogenic development to directly assess the importance of endogenously produced FGF in controlling differentiation. A role for endogenous FGF is suggested by the previous finding that acidic and basic FGF abundance in cultured myocytes decreases during differentiation. In this study we inhibited the endogenous production of FGF in murine Sol 8 myoblasts by using antisense RNA and observed precocious myogenic differentiation. Exogenously supplied acidic FGF rescues this phenotype. Further results suggest that the effect of FGF on myogenic differentiation is mediated in part through inhibition of myogenin expression. These results demonstrate a direct role for endogenously synthesized growth factors in regulating myogenesis and provide support for a general role for related proteins in mammalian development.

Actins↗
PubMed1993

Auto and transactivation of FGF expression: potential mechanism for regulation of myogenic differentiation.

Fibroblast growth factors (FGFs) are potent inhibitors of myogenic differentiation. The recent observation that the endogenous expression of acidic and basic FGF by myogenic cells decreases coordinately with differentiation suggests a regulatory role for these growth factors in myogenesis. Inasmuch as other proteins known to influence myogenesis (e.g., MyoD1 and myogenin) activate their own expression as well as the expression of other members of their family, we hypothesized that the FGFs might be capable of similar autoregulation. We examined the effect of exogenously supplied FGF on the abundance of the mRNAs encoding acidic and basic FGF in Sol 8 myoblasts, and demonstrate that either acidic or basic FGF stimulate, through paracrine mechanisms, the accumulation of the mRNAs encoding both of these FGFs. Thus FGFs can auto- and transregulate their own expression in a manner analogous to that observed for the myogenic determination proteins. In addition, similar to that previously observed for MyoD1, both acidic and basic FGF suppress myogenin expression in myoblasts. These results suggest two mechanisms whereby endogenously produced FGFs participate in the maintenance of the undifferentiated state of myogenic cells. These data provide support for paracrine, and suggest potential autocrine, roles for FGFs in the regulation of myogenic differentiation.

Animals↗
PubMed1992

C-myc protooncogene modulates cardiac hypertrophic growth in transgenic mice.

Protooncogenes such as c-myc have been implicated in the transduction of growth signals in the cardiac myocyte. We examined whether increases in c-myc expression occur in murine heart in vivo as a generalized response to the pharmacological stimulation of myocyte growth. Both triiodothyronine (T3) and the beta-adrenergic agonist isoproterenol were demonstrated to induce a rapid and transient increase in cardiac c-myc mRNA abundance, which preceded an increase in cardiac mass. We then examined whether myocyte growth could be modulated by selectively altering cardiac c-myc expression. The model system used was a strain of transgenic mice exhibiting a 20-fold increase in cardiac c-myc expression. Although in nontransgenic mice the administration of T3 and isoproterenol resulted in similar increases in cardiac mass, in transgenic mice the degree of myocardial growth induced with T3 was significantly greater than that induced with isoproterenol (P less than 0.001). This study demonstrates that increasing the basal expression of c-myc in cardiac myocytes alters the growth response of the heart in vivo to certain hypertrophic stimuli and implicates the c-myc protooncogene in the transduction of selective hypertrophic growth signals in differentiated cardiac myocytes.

Actins↗
PubMed1992

Gene transfer into coronary arteries of intact animals with a percutaneous balloon catheter.

Genetic manipulation of the vasculature may offer insights into the pathogenesis of coronary artery disease and may lead to gene therapy for disorders such as restenosis after percutaneous coronary angioplasty. The goal of this study was to develop a percutaneous method for gene transfer into coronary arteries of intact animals. Liposomes were used to facilitate transfection in coronary arteries with a plasmid containing the cDNA encoding luciferase. This reporter was chosen since it is not expressed in mammalian cells, and it can be quantified using a sensitive assay (light production). Mongrel dogs were catheterized, and DNA was delivered to coronary arteries via a porous perfusion balloon system. Luciferase expression was measured 3-5 days after the procedure, when the dogs were killed. Luciferase activity in control arteries (n = 12) was no higher than average background activity. Eight of 12 transfected arteries exhibited gene expression, averaging 4.3 +/- 2.1 pg luciferase (p less than 0.01, transfected versus control arteries). In addition, the ability to transfect DNA into femoral arteries without a transfection vehicle was tested. Five dogs were subjected to surgical transfection attempts in their femoral arteries with either DNA alone or DNA plus liposomes. Luciferase was expressed in all 10 femoral arteries; those treated with DNA alone expressed 35.6 +/- 8 pg luciferase, and those treated with DNA plus liposomes expressed 42.3 +/- 14 pg luciferase (p = 0.70). These results demonstrate the use of a percutaneous catheter to achieve gene transfer and expression in coronary arteries of intact dogs and suggest that the efficiency of intra-arterial gene transfer may be similar whether or not a transfection vehicle is used.

Animals↗