Interpretation of transcript profiling.
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False Positive Reactions↗
Biomedical subjects
A Rosenzweig
Publications and source records attributed to A Rosenzweig.
Improvement in survival and cardiac metabolism after gene transfer of sarcoplasmic reticulum Ca(2+)-ATPase in a rat model of heart failure.
BACKGROUND: In heart failure, sarcoplasmic reticulum (SR) Ca(2+)-ATPase (SERCA2a) activity is decreased, resulting in abnormal calcium handling and contractile dysfunction. We have previously shown that increasing SERCA2a expression by gene transfer improves ventricular function in a rat model of heart failure created by ascending aortic constriction. METHODS AND RESULTS: In this study, we tested the effects of gene transfer of SERCA2a on survival, left ventricular (LV) volumes, and metabolism. By 26 to 27 weeks after aortic banding, all animals developed heart failure (as documented by >25% decrease in fractional shortening) and were randomized to receive either an adenovirus carrying the SERCA2a gene (Ad.SERCA2a) or control virus (Ad.betagal-GFP) by use of a catheter-based technique. Sham-operated rats, uninfected or infected with either Ad.betagal-GFP or Ad.SERCA2a, served as controls. Four weeks after gene transfer, survival in rats with heart failure treated with Ad.betagal-GFP was 9%, compared with 63% in rats receiving Ad.SERCA2a. LV volumes were significantly increased in heart failure (0.64+/-0.05 versus 0.35+/-0.03 mL, P<0.02). Overexpression of SERCA2a normalized LV volumes (0.46+/-0.07 mL) in the failing hearts. (31)P NMR analysis showed a reduced ratio of phosphocreatine to ATP content in failing+Ad.betagal-GFP compared with sham+Ad.betagal-GFP (0.82+/-0.13 versus 1.38+/-0.14, P<0.01). Overexpression of SERCA2a in failing hearts improved the phosphocreatine/ATP ratio (1.23+/-0.28). CONCLUSIONS: In this study, we show that unlike inotropic agents that improve contractile function at the expense of increased mortality and worsening metabolism, gene transfer of SERCA2a improves survival and the energy potential in failing hearts.
Adenoviridae↗
Akt activation preserves cardiac function and prevents injury after transient cardiac ischemia in vivo.
BACKGROUND: The serine-threonine kinase Akt is activated by several ligand-receptor systems previously shown to be cardioprotective. Akt activation reduces cardiomyocyte apoptosis in models of transient ischemia. Its role in cardiac dysfunction or infarction, however, remains unclear. METHODS AND RESULTS: We examined the effects of a constitutively active Akt mutant (myr-Akt) in a rat model of cardiac ischemia-reperfusion injury. In vivo gene transfer of myr-Akt reduced infarct size by 64% and the number of apoptotic cells by 84% (P<0.005 for each). Ischemia-reperfusion injury decreased regional cardiac wall thickening as well as the maximal rate of left ventricular pressure rise and fall (+dP/dt and -dP/dt). Akt activation restored regional wall thickening and +dP/dt and -dP/dt to levels seen in sham-operated rats. To better understand this benefit, we examined the effects of myr-Akt on hypoxic cardiomyocyte dysfunction in vitro. myr-Akt prevented hypoxia-induced abnormalities in cardiomyocyte calcium transients and shortening. Akt activation also enhanced sarcolemmal expression of Glut-4 in vivo and increased glucose uptake in vitro to the level seen with insulin treatment. CONCLUSIONS: Akt activation exerts a powerful cardioprotective effect after transient ischemia that probably reflects its ability to both inhibit cardiomyocyte death and improve function of surviving cardiomyocytes. Akt may represent an important nodal target for therapy in ischemic and other heart disease.
Adenoviridae↗
Akt participation in the Wnt signaling pathway through Dishevelled.
Inactivation of glycogen synthase kinase 3beta (GSK3beta) and the resulting stabilization of free beta-catenin are critical steps in the activation of Wnt target genes. While Akt regulates GSK3alpha/beta in the phosphatidylinositide 3-OH kinase signaling pathway, its role in Wnt signaling is unknown. Here we report that expression of Wnt or Dishevelled (Dvl) increased Akt activity. Activated Akt bound to the Axin-GSK3beta complex in the presence of Dvl, phosphorylated GSK3beta and increased free beta-catenin levels. Furthermore, in Wnt-overexpressing PC12 cells, dominant-negative Akt decreased free beta-catenin and derepressed nerve growth factor-induced differentiation. Therefore, Akt acts in association with Dvl as an important regulator of the Wnt signaling pathway.
Adaptor Proteins, Signal Transducing↗
Role of phosphoinositide 3-kinase in monocyte recruitment under flow conditions.
Chemokines such as the monocyte chemol attractant protein-1 (MCP-1) convert monocyte rolling to firm arrest under physiological flow conditions via integrin activation and simultaneously activate phosphoinositide 3-kinase (PI3K). Here we used adenoviral gene transfer and biochemical inhibitors to manipulate PI3K-dependent pathways in human monocytes. In in vitro lipid kinase assays from purified human monocytes, we showed that MCP-1 activates the "classical" PI3Kalpha pathway and not PI3Kgamma, a PI3K isoform thought to be activated only by the betagamma complex of heterotrimeric G proteins. The activity of PI3Kalpha in purified human monocytes was evident within 30 s. MCP-1-induced monocyte arrest was significantly inhibited both by wortmannin (n = 4; p < 0.01) and LY294002 (n = 4; p < 0.01) with restoration of the rolling phenotype (p < 0.05 for both inhibitors, compared with rolling of control monocytes after MCP-1 treatment). To test the hypothesis that activation of PI3K is sufficient to induce monocyte adhesion, we transduced the monocytic THP-1 cell line with a recombinant adenovirus (Ad) carrying a constitutively active mutant of PI3K (Ad.BD110). We examined the ability of these cells to adhere to human vascular endothelium (HUVEC) transduced with adenoviruses carrying E-selectin, intercellular adhesion molecule-1 (ICAM-1), and VCAM-1. Under flow conditions, ICAM-1- and VCAM-1-dependent firm adhesion of Ad.BD110-transduced THP-1 cells was enhanced compared with THP-1 cells infected with control Ad (n = 4; p < 0.01 for both). Adhesion augmented by constitutive PI3K activation was entirely abrogated by pretreatment with wortmannin (n = 3; p < 0.01). In contrast, a constitutively active Akt construct had no effect on THP-1 adhesion (n = 3; p = NS). We conclude that PI3K activation is necessary and sufficient to enhance monocytic adhesion under physiological flow conditions. BD110-expressing THP-1 cells should provide a useful tool for identifying the signaling pathways downstream of PI3K that are necessary for monocyte recruitment relevant to a variety of human vascular pathologies.
Cell Line↗
Hmg-CoA reductase inhibitor modulates monocyte-endothelial cell interaction under physiological flow conditions in vitro: involvement of Rho GTPase-dependent mechanism.
3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, or statins, have been reported to exert actions independent of their lipid-lowering effects. To critically assess the effects of statins on monocyte-endothelial cell interactions, we used an in vitro model that mimicked physiological flow conditions. Monocytic U937 cells were incubated in the presence of cerivastatin for 48 hours. Adhesive interactions of statin-treated U937 cells were then analyzed by use of activated (interleukin-1beta 10 U/mL, 4 hours) human umbilical vein endothelial cells in an in vitro flow apparatus. Flow cytometric analysis of adhesion molecules and measurement of F-actin content in U937 cells were performed before and after statin treatment. Preincubation with cerivastatin significantly decreased U937 firm adhesion to activated human umbilical vein endothelial cells, whereas U937 rolling was not decreased. Fluorescence-activated cell sorter analysis revealed downregulation of U937 surface expression of CD11a, CD18, and VLA4 after statin treatment. Cerivastatin significantly reduced F-actin content in U937 cells and inhibited RhoA translocation, whereas preincubation with C3 exoenzyme reduced U937 adhesion under flow. Cerivastatin reduces monocyte adhesion to vascular endothelium under physiological flow conditions via downregulation of integrin adhesion molecules and inhibition of actin polymerization via RhoA inactivation. Our findings have important implications for the lipid-independent effects of statins.
ADP Ribose Transferases↗
Akt-mediated survival of oligodendrocytes induced by neuregulins.
Neuregulins have been implicated in a number of events in cells in the oligodendrocyte lineage, including enhanced survival, mitosis, migration, and differentiation. At least two signaling pathways have been shown to be involved in neuregulin signaling: the phosphatidylinositol (PI)-3 kinase and the mitogen-activated protein kinase pathways. In the present studies, we examined the signaling pathway involved in the survival function of heregulin, focusing on heregulin-induced changes in Akt activity in cultured glial cells, and the consequences of Akt activation in cells in the oligodendrocyte lineage. Heregulin binds erbB receptors, and in our studies, primary cultures of both oligodendrocyte progenitor cells and differentiating oligodendrocytes expressed erbB2, erbB3, and erbB4 receptors. In C6 glioma cells and primary cultures of oligodendrocytes, heregulin induced time- and dose-dependent Akt phosphorylation at Ser(473) in a wortmannin-sensitive manner. To investigate further the signaling pathway for heregulin in glial cells, BAD was overexpressed in C6 glioma cells. In these cells, heregulin induced phosphorylation of BAD at Ser(136). Apoptosis of oligodendrocyte progenitor cells induced by growth factor deprivation was effectively blocked by heregulin in a wortmannin-sensitive manner. Overexpression of dominant negative Akt but not of wild-type Akt by adenoviral gene transfer in primary cultures of both oligodendrocytes and their progenitors induced significant apoptosis through activation of the caspase cascade. The present data suggest that the survival function of heregulin is mediated through the PI-3 kinase/Akt pathway in cells in the oligodendrocyte lineage and that the Akt pathway may be quite important for survival of cells in this lineage.
Androstadienes↗
Glycogen synthase kinase-3beta is a negative regulator of cardiomyocyte hypertrophy.
Hypertrophy is a basic cellular response to a variety of stressors and growth factors, and has been best characterized in myocytes. Pathologic hypertrophy of cardiac myocytes leads to heart failure, a major cause of death and disability in the developed world. Several cytosolic signaling pathways have been identified that transduce prohypertrophic signals, but to date, little work has focused on signaling pathways that might negatively regulate hypertrophy. Herein, we report that glycogen synthase kinase-3beta (GSK-3beta), a protein kinase previously implicated in processes as diverse as development and tumorigenesis, is inactivated by hypertrophic stimuli via a phosphoinositide 3-kinase-dependent protein kinase that phosphorylates GSK-3beta on ser 9. Using adenovirus-mediated gene transfer of GSK-3beta containing a ser 9 to alanine mutation, which prevents inactivation by hypertrophic stimuli, we demonstrate that inactivation of GSK-3beta is required for cardiomyocytes to undergo hypertrophy. Furthermore, our data suggest that GSK-3beta regulates the hypertrophic response, at least in part, by modulating the nuclear/cytoplasmic partitioning of a member of the nuclear factor of activated T cells family of transcription factors. The identification of GSK-3beta as a transducer of antihypertrophic signals suggests that novel therapeutic strategies to treat hypertrophic diseases of the heart could be designed that target components of the GSK-3 pathway.
Animals↗
E-selectin-dependent signaling via the mitogen-activated protein kinase pathway in vascular endothelial cells.
E-selectin, a cytokine-inducible adhesion molecule, supports rolling and stable arrest of leukocytes on activated vascular endothelium. Previous studies have suggested that this transmembrane protein can also transduce signals into the endothelial cell. We now demonstrate activation of the mitogen-activated protein kinase (MAPK) signaling cascade in cultured HUVEC in response to E-selectin-dependent leukocyte adhesion and Ab-mediated cross-linking of cell surface E-selectin. Adhesion of increasing numbers of HL60 cells to IL-1beta-activated HUVEC stimulated robust increases in MAPK activity that were abrogated by an E-selectin blocking Ab. Cross-linking of cell surface E-selectin with Abs, as a mimic of multivalent ligand engagement, strongly stimulated MAPK/extracellular signal-related kinase (ERK) kinase (MEK)-dependent MAPK activation and concomitant up-regulation of mRNA for c-fos, an immediate early response gene, whereas Ab cross-linking of HLA class I molecules (present at comparable density) failed to do so. Coimmunoprecipitation documented Ras, Raf-1 and, phospho-MEK complex formation. Unactivated HUVEC transduced with a full-length adenoviral E-selectin construct also exhibited cross-link-induced MAPK activation, macromolecular complex formation, and c-fos up-regulation, whereas HUVEC transduced with a cytoplasmic domain deletion mutant failed to respond. These observations indicate that E-selectin can transduce an activating stimulus via the MAPK cascade into the endothelial cell during leukocyte adhesion.
Antibodies, Monoclonal↗
Prospects for gene therapy for heart failure.
Heart failure represents an enormous clinical challenge in need of effective therapeutic approaches. The possibility of gene therapy for heart failure merits consideration at this time because of improvements in vector technology; cardiac gene delivery; and, most importantly, our understanding of the molecular pathogenesis of heart failure. We will first review recent advances in cardiac gene delivery in animal models and then examine several targets being considered for therapeutic intervention. In this context, gene transfer provides not only a potential therapeutic modality but also an important tool to help validate specific targets. Several interventions, particularly those enhancing sarcoplasmic calcium transport, show promise in animal models of heart failure and in myopathic cardiomyocytes derived from patients. However, bridging the gap between these basic investigative studies and clinical gene therapy remains a formidable task. Early experiments in rodents will need to be extended to large-animal models with clinical-grade vectors and delivery systems to assess both efficacy and safety. On the basis of a foundation of rigorous science and a growing understanding of heart failure pathogenesis, there is reason for cautious optimism for the future.
Animals↗
Restoration of diastolic function in senescent rat hearts through adenoviral gene transfer of sarcoplasmic reticulum Ca(2+)-ATPase.
BACKGROUND: Senescent hearts are characterized by diastolic dysfunction and a decrease in sarcoplasmic reticulum (SR) Ca(2+)-ATPase protein (SERCA2a). METHODS AND RESULTS: To test the hypothesis that an increase in SERCA2a could improve cardiac function in senescent rats (age 26 months), we used a catheter-based technique of adenoviral gene transfer to achieve global myocardial transduction of SERCA2a in vivo. Adult rat hearts aged 6 months and senescent rat hearts infected with an adenovirus containing the reporter gene beta-galactosidase were used as controls. Two days after infection, parameters of systolic and diastolic function were measured in open-chest rats. Cardiac SERCA2a protein and ATPase activity were significantly decreased in senescent hearts compared with adult rats (Delta -30+/-4% and -49+/-5%) and were restored to adult levels after infection with Ad.SERCA2a. At baseline, left ventricular systolic pressure and +dP/dt were unaltered in senescent hearts; however, diastolic parameters were adversely affected with an increase in the left ventricular time constant of isovolumic relaxation and diastolic pressure (Delta +29+/-9% and +38+/-12%) and a decrease in -dP/dt (Delta -26+/-11%). Overexpression of SERCA2a did not significantly affect left ventricular systolic pressure but did increase +dP/dt (Delta +28+/-10%) in the senescent heart. Overexpression of SERCA2a restored the left ventricular time constant of isovolumic relaxation and -dP/dt to adult levels. Infection of senescent hearts with Ad.SERCA2a markedly improved rate-dependent contractility and diastolic function in senescent hearts. CONCLUSIONS: These results support the hypothesis that decreased Ca(2+)-ATPase activity contributes to the functional abnormalities observed in senescent hearts and demonstrates that Ca(2+) cycling proteins can be targeted in the senescent heart to improve cardiac function.
Adenoviridae↗
Adenoviral gene transfer of SERCA2a improves left-ventricular function in aortic-banded rats in transition to heart failure.
In human and experimental models of heart failure, sarcoplasmic reticulum Ca(2+) ATPase (SERCA2a) activity is decreased, resulting in abnormal calcium handling. The disturbances in calcium metabolism have been shown to contribute significantly to the contractile dysfunction observed in heart failure. We investigated whether increasing SERCA2a expression can improve ventricular function in an animal model of heart failure obtained by creating ascending aortic constriction in rats. After 19-23 wk of banding during the transition from compensated hypertrophy to heart failure (documented by >25% decrease in fractional shortening), rats were randomized to receive either an adenovirus carrying the SERCA2a gene (Ad.SERCA2a, n = 13) or beta-galactosidase (Ad.betagal, n = 14) by using a catheter-based technique. The failing hearts infected with Ad. betagal were characterized by a significant decrease in SERCA2a expression and a decrease in SERCA2a activity compared with nonfailing sham-operated rats (n = 11). In addition, these failing hearts had reduced left-ventricular systolic pressure, maximal rate of left-ventricular pressure rise and decline (+dP/dt, -dP/dt), and rate of isovolumic relaxation (tau). Overexpression of SERCA2a restored both SERCA2a expression and ATPase activity to nonfailing levels. Furthermore, rats infected with Ad.SERCA2a had significant improvement in left-ventricular systolic pressure, +dP/dt, -dP/dt, and rate of isovolumic relaxation (tau) normalizing them back to levels comparable to sham-operated rats. In this study, we show that in an animal model of heart failure where SERCA2a protein levels and activity are decreased and severe contractile dysfunction is present, overexpression of SERCA2a in vivo restores both systolic and diastolic function to normal levels.
Adenoviridae↗
Cell-dependent mechanisms restrict the HIV type 1 coreceptor activity of US28, a chemokine receptor homolog encoded by human cytomegalovirus.
Several members of the chemokine receptor family are used together with CD4 for HIV-1 entry into target cells. The human cytomegalovirus US28 gene encodes a chemokine receptor homolog that has been reported to function as an HIV-1 coreceptor. However, studies of US28 have given conflicting results regarding its ability to mediate HIV-1 entry. We examined the ability of US28 to function as an HIV-1 coreceptor in various cell lines and found that its coreceptor activity is highly cell dependent. US28 could function as a coreceptor for HIV-1 entry in HeLa and U87 cells but not in COS-1 and Cf2Th cells. In COS-1 cells, US28 was expressed on the cell surface and could mediate cell-cell fusion with HIV-1 Env-expressing cells, suggesting that the block to infection may result from a defect in virus internalization or postentry steps. In Cf2Th cells, US28 was expressed at high levels intracellularly but was not transported to the cell surface. The block in US28 coreceptor function in COS-1 and Cf2Th cells was coreceptor dependent, since CCR5, CXCR4, and other coreceptors can mediate HIV-1 entry in these cell lines. HIV-1 viruses pseudotyped with the MuLV or VSV Env entered and replicated at similar efficiency in COS-1 and U87 cells in single-cycle infections, suggesting that postentry and other early events in the HIV-1 life cycle are not intrinsically inefficient in COS-1 cells. These results identify two distinct mechanisms that can restrict the HIV-1 coreceptor activity of US28 in a cell- and coreceptor-dependent manner, and help to explain the existing controversy regarding the ability of US28 to mediate HIV-1 entry.
Animals↗
Chemokines, leukocytes, and atherosclerosis.
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Animals↗
C-C and C-X-C chemokines trigger firm adhesion of monocytes to vascular endothelium under flow conditions.
In summary, our findings indicate that specific chemokines that are elaborated by endothelial cells after cytokine or endotoxin activation can play an essential role in monocyte recruitment beyond their chemoattractant activities. We show that this action is to translate initial monocyte tethering into firm adhesion via rapid leukocyte integrin activation. The in vitro model presented here provides a sensitive system for investigating the modulating ability of chemokines and reveals an important biological effect that is not predicted by results in simpler in vitro assays, such as measurement of calcium transients or chemotaxis. The surprising finding that the C-X-C chemokine IL-8 can trigger monocyte firm adhesion to vascular endothelium suggests a potential role for this chemokine in monocyte recruitment and underscores the biological complexity of the chemokine family.
Cell Adhesion↗
Cytosolic phospholipase A(2) regulates golgi structure and modulates intracellular trafficking of membrane proteins.
The Golgi complex and the trans-Golgi network are critical cellular organelles involved in the endocytic and biosynthetic pathways of protein trafficking. Lipids have been implicated in the regulation of membrane-protein trafficking, vesicular fusion, and targeting. We have explored the role of cytosolic group IV phospholipase A(2) (cPLA(2)) in membrane-protein trafficking in kidney epithelial cells. Adenoviral expression of cPLA(2) in LLC-PK(1) kidney epithelial cells prevents constitutive trafficking to the plasma membrane of an aquaporin 2-green fluorescent protein chimera, with retention of the protein in the rough endoplasmic reticulum. Plasma membrane Na(+)-K(+)-ATPase alpha-subunit localization is markedly reduced in cells expressing cPLA(2), whereas the trafficking of a Cl(-)/HCO(3)(-) anion exchanger to the plasma membrane is not altered in these cells. Expression of cPLA(2) results in dispersion of giantin and beta-COP from their normal, condensed Golgi localization, and in marked disruption of the Golgi cisternae. cPLA(2) is present in Golgi fractions from noninfected LLC-PK(1) cells and rat kidney cortex. The distribution of tubulin and actin was not altered by cPLA(2), indicating that the microtubule and actin cytoskeleton remain intact. Total cellular protein synthesis is unaffected by the increase in cPLA(2) activity. Thus cPLA(2) plays an important role in determining Golgi architecture and selective control of constitutive membrane-protein trafficking in renal epithelial cells.
Antiporters↗
Adenoviral transduction of human E-selectin into isolated, perfused, rat aortic segments: an ex vivo model for studying leukocyte-endothelial interactions.
E-selectin, a member of the selectin family of adhesion molecules, is thought to play an important role in leukocyte-endothelial (EC) interactions during inflammation and atherosclerosis. To critically examine the role of E-selectin in leukocyte-EC interactions in the vascular system, we created a recombinant adenoviral vector containing a human E-selectin cDNA (AdRSVE-sel) and examined the effect of AdRSVE-sel in an ex vivo vascular model of a rat aortic segment. A segment of abdominal aorta was isolated from a male Sprague-Dawley rat transduced with AdRSVE-sel ex vivo. After 72 h, surface expression of transduced E-selectin in the segment was confirmed by Western blotting and immunohistochemistry using anti-E-selectin mAb. Aortic segments were connected to a perfusion system and the adhesion of human polymorphonuclear neutrophils (PMN), and a human monocytic cell line (THP-1) to the EC surface was studied in the presence of a physiological level of flow (0.85 ml/min, approximate luminal surface shear stress=1.76 dyn/cm2). Adhesion of PMN was assessed by scanning electron microscopy and quantified using fluorescently labeled PMN. AdRSVE-sel transduced aortic segments mediated significantly more PMN and THP-1 adhesion than control segments transduced with AdRSVLacZ. Pretreatment of AdRSVE-sel transduced aortic segments with anti-E-selectin mAb inhibited PMN adhesion significantly, as well as THP-1. These data indicate that human E-selectin expressed in rat aortic segments can support the adhesion of human PMN as well as THP-1 under physiological flow conditions. This genetically modified, excised, vascular-segment model provides a useful tool for the study of leukocyte recruitment in the vascular system.
Adenoviridae↗
Restoration of contractile function in isolated cardiomyocytes from failing human hearts by gene transfer of SERCA2a.
BACKGROUND: Failing human myocardium is characterized by abnormal relaxation, a deficient sarcoplasmic reticulum (SR) Ca(2+) uptake, and a negative frequency response, which have all been related to a deficiency in the SR Ca(2+) ATPase (SERCA2a) pump. METHODS AND RESULTS: To test the hypothesis that an increase in SERCA2a could improve contractile function in cardiomyocytes, we overexpressed SERCA2a in human ventricular myocytes from 10 patients with end-stage heart failure and examined intracellular Ca(2+) handling and contractile function. Overexpression of SERCA2a resulted in an increase in both protein expression and pump activity and induced a faster contraction velocity (26.7+/-6.7% versus 16.6+/-2.7% shortening per second, P<0.005) and enhanced relaxation velocity (32. 0+/-10.1% versus 15.1+/-2.4%, P<0.005). Diastolic Ca(2+) was decreased in failing cardiomyocytes overexpressing SERCA2a (270+/-26 versus 347+/-30 nmol/L, P<0.005), whereas systolic Ca(2+) was increased (601+/-38 versus 508+/-25 nmol/L, P<0.05). In addition, the frequency response was normalized in cardiomyocytes overexpressing SERCA2a. CONCLUSIONS: These results support the premise that gene-based therapies and targeting of specific pathways in human heart failure may offer a new modality for the treatment of this disease.
Calcium↗