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At least 1,099 records · Page 61Linked to original sources
PubMed2006

PTP-H2 and PTP-H3 from Microplitis demolitor Bracovirus localize to focal adhesions and are antiphagocytic in insect immune cells.

Viruses in the family Polydnaviridae are symbiotically associated with parasitoid wasps. Wasps inject polydnaviruses (PDVs) when laying an egg into their insect host, and expression of viral gene products causes several physiological alterations, including immunosuppression, that allow the wasp's progeny to develop. As with other PDVs, most Microplitis demolitor bracovirus (MdBV) genes are related variants that form gene families. The largest MdBV gene family includes 13 members that encode predicted proteins related to protein tyrosine phosphatases (PTPs). Sequence analysis during the present study indicated that five PTP family members (PTP-H2, -H3, -N1, and -N2) have fully conserved catalytic domains, whereas other family members exhibited replacements, deletions, or rearrangements of amino acids considered essential for tyrosine phosphatase activity. Expression studies indicated that most MdBV PTP genes are expressed in virus-infected host insects, with transcript abundance usually being highest in hemocytes. MdBV-infected hemocytes also exhibited higher levels of tyrosine phosphatase activity than noninfected hemocytes. We produced expression constructs for four of the most abundantly expressed PTP family members and conducted functional studies with hemocyte-like Drosophila S2 cells. These experiments suggested that recombinant PTP-H2 and PTP-H3 are functional tyrosine phosphatases whereas PTP-H1 and PTP-J1 are not. PTP-H2 and -H3 localized to focal adhesions in S2 cells, and coexpression with another MdBV gene product, Glc1.8, resulted in complete inhibition of phagocytosis.

Animals↗
PubMed1997

A LAT-associated function reduces productive-cycle gene expression during acute infection of murine sensory neurons with herpes simplex virus type 1.

Herpes simplex virus (HSV) persists in the human population by establishing long-term latent infections followed by periodic reactivation and transmission. Latent infection of sensory neurons is characterized by repression of viral productive-cycle gene expression, with abundant transcription limited to a single locus that encodes the latency-associated transcripts (LATs). We have observed that LAT- deletion mutant viruses express viral productive-cycle genes in greater numbers of murine trigeminal ganglion neurons than LAT+ HSV type 1 at early times during acute infection but show reduced reactivation from latent infection. Thus, a viral function associated with the LAT region exerts an effect at an early stage of neuronal infection to reduce productive-cycle viral gene expression. These results provide the first evidence that the virus plays an active role in down-regulating productive infection during acute infection of sensory neurons. The effect of down-regulation of productive-cycle gene expression during acute infection may contribute to viral evasion from the host immune responses and to reduced cytopathic effects, thereby facilitating neuronal survival and the establishment of latency.

Animals↗
PubMed2001

Effects of deletion and overexpression of the Autographa californica nuclear polyhedrosis virus FP25K gene on synthesis of two occlusion-derived virus envelope proteins and their transport into virus-induced intranuclear membranes.

Partial deletions within Autographa californica open reading frame 61 (FP25K) alter the expression and accumulation profile of several viral proteins and the transport of occlusion-derived virus (ODV)-E66 to intranuclear membranes during infection (S. C. Braunagel et al., J. Virol. 73:8559-8570, 1999). Here we show the effects of a full deletion and overexpression of FP25K on the transport and expression of two ODV envelope proteins, ODV-E66 (E66) and ODV-E25 (E25). Deletion and overexpression of FP25K substantially altered the levels of expression of E66 during infection. Compared with cells infected with wild-type (wt) virus, the levels of E66 were reduced fivefold in cells infected with a viral mutant lacking FP25K (DeltaFP25K) and were slightly increased in cells infected with a viral mutant overexpressing FP25K (FP25K(polh)). In contrast, no significant changes were observed in the levels of E25 among wt-, DeltaFP25K-, and FP25K(polh)-infected cells. The changes observed in the levels of E66 among the different viral mutants were not accompanied by changes in either the time of synthesis, membrane association, protein turnover, or steady-state transcript abundance. Deletion of FP25K also substantially altered the transport and localization of E66 during infection. In cells infected with the DeltaFP25K mutant virus, E66 accumulated in localized regions at the nuclear periphery and the outer nuclear membrane and did not traffic to intranuclear membranes. In contrast, in cells infected with the FP25K(polh) mutant virus E66 trafficked to intranuclear membranes. For comparison, E25 was normally transported to intranuclear membranes in both DeltaFP25K- and FP25K(polh)-infected cells. Altogether these studies suggest that FP25K affects the synthesis of E66 at a posttranscriptional level, probably by altering the translation of E66; additionally, the block in transport of E66 at the nuclear envelope in DeltaFP25K-infected cells suggests that the pathway of E66 trafficking to the inner nuclear membrane and intranuclear microvesicles is specifically regulated and must be influenced by factors that do not control the traffic of E25.

Animals↗
PubMed2005

Regions of the varicella-zoster virus open reading frame 63 latency-associated protein important for replication in vitro are also critical for efficient establishment of latency.

Varicella-zoster virus (VZV) open reading frame 63 (ORF63) is one of the most abundant transcripts expressed during VZV latency in humans, and ORF63 protein has been detected in human ganglia by several laboratories. Deletion of over 90% of the ORF63 gene showed that the protein is required for efficient establishment of latency in rodents. We have constructed viruses with a series of mutations in ORF63. While prior experiments showed that transfection of cells with a plasmid expressing ORF63 but lacking the putative nuclear localization signal of the protein resulted in increased expression of the protein in the cytoplasm, we found that ORF63 protein remained in the nucleus in cells infected with a VZV ORF63 nuclear localization signal deletion mutant. This mutant was not impaired for growth in cell culture or for latency in rodents. Replacement of five serine or threonine phosphorylation sites in ORF63 with alanines resulted in a virus that was impaired for replication in vitro and for latency. A series of ORF63 carboxy-terminal mutants showed that the last 70 amino acids do not affect replication in vitro or latency in rodents; however, the last 108 amino acids are important for replication and latency. Thus, regions of ORF63 that are important for replication in vitro are also required for efficient establishment of latency.

Animals↗
PubMed2006

Cell divisions are required for L1 retrotransposition.

LINE-1 (L1) retrotransposons comprise a large fraction of genomic DNAs of many organisms. Many L1 elements are active and may generate potentially deleterious mutations by inserting into genes, yet little is known about the control of retrotransposition by the host. Here we examined whether retrotransposition depends on the cell cycle by using a retrotransposition assay with cultured human cells. We show that in both cancer cells and primary human fibroblasts, retrotransposition was strongly inhibited in the cells arrested in the G(1), S, G(2), or M stage of the cell cycle. Retrotransposition was also inhibited during cellular senescence in primary human fibroblasts. The levels of L1 transcripts were strongly reduced in arrested cells, suggesting that the reduction in L1 transcript abundance limits retrotransposition in nondividing cells. We hypothesize that inhibition of retrotransposition in nondividing cells protects somatic tissues from accumulation of deleterious mutations caused by L1 elements.

Cell Division↗
PubMed1993

Mutations in the Drosophila gene encoding ribosomal protein S6 cause tissue overgrowth.

We have characterized two P-element-induced, lethal mutations in Drosophila melanogaster which affect the larval hemocytes, mediators of the insect immune response. Each mutant displays larval melanotic tumors characteristic of mutations affecting the insect cellular immune system, and the moribund animals develop grossly hypertrophied hematopoietic organs because of increased cell proliferation and extra rounds of endoreduplication in some hematopoietic cells. Surprisingly, these mutations are due to P element insertions in the 5' regulatory region of the Drosophila gene encoding ribosomal protein S6 and cause a reduction of S6 transcript abundance in mutant larvae.

Animals↗
PubMed2026

Genome-wide analysis of lipoxygenase genes in Coffea arabica and its diploid progenitors.

Lipoxygenase proteins (LOXs) play a crucial role in plant growth, development, and defense notably through their involvement in jasmonic acid (JA) biosynthesis. Here, we aimed to identify and characterize genes encoding LOXs in three coffee species, Coffea arabica, Coffea canephora, and Coffea eugenioides, and to evaluate whether LOX genes are differentially expressed following hexanoic acid application in Coffea arabica. We found 18 LOX genes in Coffea arabica and 9 genes each in Coffea eugenioides and Coffea canephora. Chromosomal localization analyses revealed strong correspondence between the LOX genes of tetraploid Coffea arabica and those of its putative diploid progenitors, Coffea eugenioides and Coffea canephora. Transcriptomic and enzymatic analyses showed that hexanoic acid application modulates the expression of specific LOX genes and alters LOX activity in leaves and roots of Coffea arabica cvs. Catuaí Vermelho and Obatã. Notably, three LOX genes displayed strong correlations between transcript abundance and enzymatic activity. Together, these results indicate that a subset of LOX genes in Coffea arabica represents promising candidates for detailed functional analyses, as they likely contribute substantially to LOX activity and elicitor-induced defense responses in Coffea species.

Coffea↗
PubMed1993

Antidiabetic agent pioglitazone enhances adipocyte differentiation of 3T3-F442A cells.

Adipocytes play an important role in normal physiology as a major site for systemic energy homeostasis. In disorders such as diabetes, adipocyte function is markedly altered. In this study, we investigated the effect of pioglitazone, a novel antidiabetic agent known to lower plasma glucose in animal models of diabetes mellitus, on cellular differentiation and expression of adipose-specific genes. Treatment of confluent 3T3-F442A preadipocyte cultures for 7 days with pioglitazone (Pio; 1 microM) and insulin (Ins; 0.17 microM) resulted in > 95% cell differentiation into lipid-accumulating adipocytes in comparison with 60-80% cell differentiation by treatment with either agent alone. Analysis of triglyceride accumulation showed increases of triglyceride content over time above untreated preadipocytes by treatment of the cells with Ins, Pio, and especially with Ins + Pio. Basal glucose transport, as measured by cellular uptake of 2-deoxy-D-[14C]glucose, was likewise enhanced in a time-dependent manner by treatment of preadipocytes with Ins, Pio, or Ins + Pio, such that a synergistic effect resulted from the combined treatment with both agents. It was further determined that RNA transcript abundance for genes encoding glucose transporters GLUT-1 and GLUT-4, as well as the adipose-specific genes encoding adipsin and aP2, were increased by the Ins, Pio, or Ins + Pio treatment. Taken together, these findings indicate that pioglitazone is a potent adipogenic agent. By promoting differentiation, this agent may move cells into a state active for glucose uptake, storage, and metabolism.

3T3 Cells↗
PubMed1998

Sympathetic innervation modulates repolarizing K+ currents in rat epicardial myocytes.

During postnatal development, sympathetic innervation of the heart evolves, and repolarization accelerates. Our goal in this study was to test whether sympathetic innervation modulates the ion channels that regulate repolarization. We studied action potentials and repolarizing K+ currents in epicardial myocytes from rats in which sympathetic innervation was accelerated or delayed, respectively, by subcutaneous injection of nerve growth factor (NGF) or NGF antibody (Ab) for the first 15 days of life. A placebo group was included as well. Action potential duration (APD) to 90% repolarization was greater in the Ab (158 +/- 18 ms)-treated than the NGF (106 +/- 10 ms)-treated animals (P < 0.05); the APD at 90% repolarization for the placebo group was intermediate (125 +/- 30 ms). The transient outward (Ito) and inward rectifier (IK1) K+ currents were recorded in freshly dissociated cells using the whole cell patch-clamp technique. Ito was decreased in density at potentials positive to +40 mV in Ab-treated rats when compared with rats treated with NGF (P < 0.05). In addition, the inactivation curve of Ito in Ab-treated rats was shifted 13 mV positive to that of NGF-treated rats. IK1 also decreased in the Ab-treated group compared with the NGF group in the potential ranges of -100 to -90 mV (P < 0.05). However, the channel transcript abundance (RNA) in NGF-, Ab-, or placebo-treated rat hearts did not differ. Our results suggest that sympathetic innervation contributes to the developmental differences in K+ currents and APD postnatally in the rat.

4-Aminopyridine↗
PubMed2004

Induction of endothelial nitric oxide synthase expression by melanoma sensitizes endothelial cells to tumor necrosis factor-driven cytotoxicity.

PURPOSE: The cascade of molecular events leading to tumor necrosis factor (TNF)-mediated tumor regression is still incompletely elucidated. We investigated the role of endothelial nitric oxide synthase in determining the tumor-selective activity of TNF. EXPERIMENTAL DESIGN: Using quantitative real-time PCR, endothelial nitric oxide synthase gene levels were measured in melanoma metastases of the skin and normal skin biopsies obtained from 12 patients before undergoing TNF-based therapy. In vitro, the ability of melanoma cells supernatant to affect endothelial nitric oxide synthase transcription by endothelial cells and the influence of nitric oxide synthase inhibition on TNF cytotoxicity toward endothelial cells was evaluated. RESULTS: Endothelial nitric oxide synthase transcript abundance resulted significantly greater in tumor samples rather than in normal skin samples and in patients showing complete response to TNF-based treatment rather than in those showing partial/minimal response. In vitro, melanoma cells' supernatant induced endothelial nitric oxide synthase gene expression by endothelial cells. Nitric oxide synthase inhibition slowed endothelial cells proliferation and, if induced before TNF administration, decreased the cytokine-mediated cytotoxicity on endothelial cells. CONCLUSIONS: Taken together, these findings support the hypothesis that high expression of endothelial nitric oxide synthase in the tumor microenvironment might increase or be a marker for endothelial cells sensitivity to TNF. These observations may have important prognostic and/or therapeutic implications in the clinical setting.

Biopsy↗
PubMedDate not supplied

Interleukin-1beta induces different gene expression of stromelysin, aggrecan and tumor-necrosis-factor-stimulated gene 6 in human osteoarthritic chondrocytes in vitro.

OBJECTIVE: To analyze the gene expression of osteoarthritic chondrocytes cultured in alginate after stimulation with interleukin (IL)-1beta. METHODS: Chondrocytes were isolated from osteoarthritic cartilage obtained during total knee replacement by sequential enzymatic digestion. After suspension in alginate, cells were cultured with and without 100 pg/ml IL-1beta. Quantitative RT-PCR reaction was used to estimate the messenger RNA (mRNA) of three different metabolites [tumor-necrosis-factor-stimulated gene 6 (TSG-6), stromelysin-1 (MMP-3) and aggrecan (AGG)]. RESULTS: After having shown the precision of quantitative PCR, this method allowed us to detect IL-1beta-induced changes in mRNA of TSG-6, MMP-3 and AGG. MMP-3 was found to be the most abundant transcript, IL-1beta induced a 12-fold upregulation of MMP-3 levels compared to control, and 7-fold of TSG-6. The AGG transcript level, indicating anabolic events, was found to be downregulated by between 2- and 3-fold. CONCLUSIONS: In our culture system, the response of osteoarthritic chondrocytes to IL-1beta is preserved. Therefore, this system might be helpful for further investigation of the influences of drugs, cytokines and growth factors, for example, on the metabolism of chondrocytes at the level of gene transcription as the most basic level of regulation.

Aged↗
PubMed2004

An integrative genomics approach to the reconstruction of gene networks in segregating populations.

The reconstruction of genetic networks in mammalian systems is one of the primary goals in biological research, especially as such reconstructions relate to elucidating not only common, polygenic human diseases, but living systems more generally. Here we propose a novel gene network reconstruction algorithm, derived from classic Bayesian network methods, that utilizes naturally occurring genetic variations as a source of perturbations to elucidate the network. This algorithm incorporates relative transcript abundance and genotypic data from segregating populations by employing a generalized scoring function of maximum likelihood commonly used in Bayesian network reconstruction problems. The utility of this novel algorithm is demonstrated via application to liver gene expression data from a segregating mouse population. We demonstrate that the network derived from these data using our novel network reconstruction algorithm is able to capture causal associations between genes that result in increased predictive power, compared to more classically reconstructed networks derived from the same data.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed2005

Cathepsin E is a specific marker of dysplasia in APC mouse intestine.

Transcriptional profiling of APC(Min/+) mouse intestinal epithelial tissue has revealed that cathepsin E (catE) manifests high relative expression in adenomas and carcinomas relative to normal epithelium. Real-time RT-PCR data presented previously confirm the presence of catE transcript in APC(Min/+) adenomatous cells compared with samples derived from normal APC(Min/+) and wild-type tissue. At the protein level, strong, highly specific immunohistochemical staining for catE is displayed in dysplastic lesions of APC(Min/+) mice. Using Western immunoblot analyses, it was additionally established that the urine of tumor-bearing mice contains higher levels of the monomeric form of catE than their wild-type counterparts. These results authenticate the relationship between transcript abundance and protein levels in transformed tissue and suggest potential utility for catE as a marker for the inception and progression of intestinal cancers.

Adenoma↗
PubMed2003

Enzymatically modified LDL induces cathepsin H in human monocytes: potential relevance in early atherogenesis.

OBJECTIVE: Modification with proteases and cholesterylesterase transforms LDL to a moiety that resembles lipoproteins isolated from atherosclerotic lesions and possesses atherogenic properties. To identify changes in monocyte-derived foam cells laden with enzymatically modified LDL (E-LDL), we compared patterns of the most abundant transcripts in these cells after incubation with LDL or E-LDL. METHODS AND RESULTS: Serial analyses of gene expression (SAGE) libraries were constructed from human monocytes after treatment with LDL or E-LDL. Several tags were differentially expressed in LDL-treated versus E-LDL-treated cells, whereby marked selective induction by E-LDL of cathepsin H was conspicuous. We show that cathepsin H is expressed in atherosclerotic lesions in colocalization with E-LDL. Furthermore, we demonstrate that LDL modified with cathepsin H and cholesterylesterase can confer onto LDL the capacity to induce macrophage foam cell formation and to induce cathepsin H. CONCLUSIONS: Cathepsin H could contribute to the transformation of LDL to an atherogenic moiety; the process might involve a self-sustaining amplifying circle.

Cathepsin H↗
PubMed2000

Protein-tyrosine phosphatases in the vessel wall: differential expression after acute arterial injury.

Many protein-tyrosine phosphatases (PTPases) have now been identified, but little is known about PTPase expression and regulation in vascular tissue and in vascular disease. Polymerase chain reaction (PCR) amplification and cDNA fingerprinting of PTPase catalytic domains, combined with random sequencing of PCR product libraries, identified 18 (8 receptor-like and 10 cytosolic) PTPases in the rat carotid artery and revealed differential expression of 5 of these PTPases during neointima formation after balloon catheter injury. In situ hybridization was used to localize mRNA expression in vessel cross sections for the 5 differentially expressed PTPases. This revealed that for 3 PTPases (SHP1, CD45, and PTPbeta), differential transcript abundance was due to appearance/loss of the cell types by which they were expressed (leukocytes for SHP1 and CD45, endothelial cells for PTPbeta). However, mRNA expression of 2 PTPases (PTPL1 and PTP1B) was specifically upregulated by proliferating and migrating smooth muscle cells (SMCs) in characteristic temporal and regional patterns in response to vessel damage. Quantitative PCR analysis showed that PTP1B and PTPL1 were induced approximately 30-fold and approximately 60-fold, respectively, by 2 weeks after injury in the damaged vessels compared with the uninjured vessels. PTP1B was rapidly upregulated in the media after vessel injury and remained highly expressed in the developing neointima. By contrast, PTPL1 expression did not increase dramatically until the SMCs had migrated into the intima. The differential expression of PTP1B and PTPL1 by SMCs after injury suggests roles for these PTPases in the regulation of vessel wall remodeling.

Animals↗
PubMed2004

Altered subcellular distribution of Na+,K+-ATPase in proximal tubules in young spontaneously hypertensive rats.

During early development of hypertension, the spontaneously hypertensive rat (SHR) demonstrates increased proximal tubule sodium reabsorption. Our previous observations of reduced Na+,K+-ATPase catalytic alpha1 and gamma subunit transcript abundance in SHR proximal tubule led us to test the hypothesis that increased proximal tubule sodium reabsorption may be attributable to altered subunit protein abundance, post-translational modification, or a shift in subcellular alpha1 and gamma distribution toward the basolateral membrane. We now extend previous gene expression studies by analyzing total cellular alpha1 and gamma protein abundance in proximal tubule from SHR compared with matched Wistar-Kyoto (WKY) controls. We also used sucrose density-gradient centrifugation to isolate basolateral, early, and late endosomal membrane-enriched fractions as well as cell surface biotinylation to test the hypothesis of altered subunit subcellular distribution in the SHR proximal tubule. At 4 weeks of age, significantly greater amounts of alpha1 were present in basolateral membrane-enriched fractions of SHR than WKY (21.1+/-1.8% versus 12.3+/-1.8%; P<0.005), and there was a concomitant reduction of alpha1 in late endosomal membrane-enriched fractions of SHR (63.3+/-2.7% versus 74.8+/-4.3%; P<0.05). This finding was confirmed in cell surface biotinylation studies that showed higher alpha1 (1.45+/-0.1-fold greater; P<0.05) and gamma-subunit (3.48+/-0.7-fold greater; P<0.01) abundance in 4-week-old SHR proximal tubule plasma membrane compared with matched WKY samples. These studies support the hypothesis that development of hypertension in SHR may involve an altered subcellular distribution of proximal tubule Na+,K+-ATPase subunits.

Animals↗
PubMed2000

Cyclophilin B expression in renal proximal tubules of hypertensive rats.

Rat cyclophilin-like protein (Cy-LP) is a candidate hypertension gene initially identified by differential hybridization and implicated in renal mechanisms of salt retention and high blood pressure. We report the molecular characterization of rat cyclophilin B (CypB) and demonstrate, through sequence analysis and an allele-specific polymerase chain reaction primer assay, that CypB but not Cy-LP is expressed in rat kidney. CypB is an endoplasmic reticulum-localized prolyl-isomerase that interacts with elongation initiation factor 2-beta, an important regulator of protein translation and a central component of the endoplasmic reticulum stress response to hypoxia or ATP depletion. Active renal transport of sodium is increased in the spontaneously hypertensive rat (SHR), and there is evidence that this coincides with hypoxia and ATP depletion in the renal cortex. In the present studies we have examined expression of CypB in rat proximal tubules, which contributes to the increased renal sodium reabsorption in this model of hypertension. We report that CypB transcript abundance is significantly elevated in proximal convoluted tubules from SHR compared with the control Wistar-Kyoto strain. This upregulation occurs in weanling animals and precedes the development of hypertension, indicating that it is not a simple response to hypertension in SHR. Further, CypB expression is also higher in a proximal tubule cell line derived from SHR compared with a similar line derived from Wistar-Kyoto rats, indicating that this difference is genetically determined. No sequence differences were observed in the CypB cDNA from these 2 strains. These observations suggest that a genetically determined alteration in proximal tubules from SHR occurs that leads to increased expression of CypB. In view of evidence linking CypB to the regulation of elongation initiation factor-2, the upregulation of CypB may result from metabolic stress.

Animals↗
PubMed1998

Versican expression is associated with chamber specification, septation, and valvulogenesis in the developing mouse heart.

The versican (PG-M) gene encodes a chondroitin sulfate proteoglycan that is nonpermissive for cell migration and appears in association with slow cell proliferation and cytodifferentiation. Using the techniques of in situ hybridization and immunocytochemistry on sectioned mouse embryos, we found that the mRNA and protein for versican show similar distributions and are expressed in a dynamic pattern during development of the heart. Versican exhibits generalized expression in the tubular heart but becomes rapidly downregulated in the atrium and exhibits higher transcript levels on the right side of the ventricular chamber than the left, before the onset of ventricular septation. Versican is expressed strongly in the trabeculated ventricular myocardium, whereas the compact proliferative zone has lower transcript abundance. It is expressed in the outer layers and on the crest of the ventricular septum and is prominent on the mesenchymal cap of the primary atrial septum. Versican is particularly strongly expressed in the endocardial cushions of the atrioventricular and outflow tract regions and in the atrioventricular, semilunar, and venous valves. This study raises the possibility that versican may be involved in specification of the ventricular chambers, in growth and fusion of the atrial and ventricular septa, and in the transformation from epithelium to mesenchyme that characterizes development of the endocardial cushions. Versican may be a key participant in cardiogenesis, responding to the many diffusible signals that mediate interactions between the developing endocardium and myocardium.

Animals↗