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PubMed1998

Arachidonate-induced tyrosine phosphorylation of epidermal growth factor receptor and Shc-Grb2-Sos association.

-Protein tyrosine phosphorylation induced by arachidonic acid (AA), an important lipid second messenger, was investigated in rabbit renal proximal tubule epithelial cells. AA stimulated tyrosine phosphorylation of a number of proteins with estimated molecular weights of 42, 44, 52, 56, 85, and 170/180 kDa. The phosphoproteins pp44 and pp42 were identified as 2 isoforms of mitogen-activated protein kinase (MAPK). Phosphorylation of MAPK in response to AA was transient, dose-dependent, and accompanied by an increase in its activity. The mechanism of AA-induced MAPK activation in RTE cells was protein kinase C-independent and involved tyrosine phosphorylation of adaptor protein Shc and its association with Grb2-Sos complex. Moreover, stimulation of RTE cells with AA resulted in significant phosphorylation of epidermal growth factor (EGF) receptor and its association with Shc. The effect of AA on EGF receptor phosphorylation, its association with Shc, and MAPK activation was similar to the effect of 1 ng/mL EGF. Tyrphostin AG1478, a specific inhibitor of EGF receptor tyrosine kinase activity, completely blocked the effects of AA and EGF but not phorbol ester on MAPK phosphorylation. These data suggest that in renal tubular epithelial cells, the mechanism of AA-induced MAPK activation involves tyrosine phosphorylation of EGF receptor and its association with Shc and Grb2-Sos complex. Given the critical role of AA in signaling linked to G protein-coupled receptors (GPCRs), these observations provide a mechanism for cross talk between GPCRs linked to phospholipases and the tyrosine kinase receptor signaling cascades.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Genetic and pharmacological basis for therapeutic inhibition of beta- and gamma-secretases in mouse models of Alzheimer's memory deficits.

Alzheimer's disease (AD) is a dementing neurodegenerative disorder for which effective disease-modifying therapeutic treatments have not yet been developed. Genetic and molecular biological studies provide accumulating evidence supporting the hypothesis that the production of amyloid-beta (Abeta) peptides, especially neurotoxic Abeta42, is central to the pathophysiology of AD--the 'amyloid cascade' hypothesis. Abeta is proteolytically generated from a type I integral membrane amyloid precursor protein by the sequential action of two enzymes, called beta- and gamma-secretase, in reference to their cleavage sites at the N- and C-terminals, respectively. Given the strong association between Abeta and AD, the strategies to inhibit the production of Abeta, the first step of the amyloid cascade, should prove beneficial as truly disease-modifying therapeutic approaches for the treatment of AD. Recent advances in genetic strategies including knockouts, transgenics and virus-delivered small interfering RNAs and the development of potent and specific small-molecule inhibitors have opened a new window to test the impacts of beta- and gamma-secretase inhibition in vivo. Since cognitive deficits are at the heart of AD, one of the most important challenges is to determine the therapeutic potential of secretase-inhibiting approaches for AD-related memory deficits, linking perspectives through the prism of molecular/pathological events and those through behavioral and neurophysiological manifestations. I review recent progress in this field, with special focus on the functional consequences of beta- and gamma-secretase inhibition and altered amyloid neuropathology in mouse models of AD memory deficits.

Alzheimer Disease↗
PubMed2004

IL-13 activates a mechanism of tissue fibrosis that is completely TGF-beta independent.

Fibrosis is a characteristic feature in the pathogenesis of a wide spectrum of diseases. Recently, it was suggested that IL-13-dependent fibrosis develops through a TGF-beta1 and matrix metalloproteinase-9-dependent (MMP-9) mechanism. However, the significance of this pathway in a natural disorder of fibrosis was not investigated. In this study, we examined the role of TGF-beta in IL-13-dependent liver fibrosis caused by Schistosoma mansoni infection. Infected IL-13-/- mice showed an almost complete abrogation of fibrosis despite continued and undiminished production of TGF-beta1. Although MMP-9 activity was implicated in the IL-13 pathway, MMP-9-/- mice displayed no reduction in fibrosis, even when chronically infected. To directly test the requirement for TGF-beta, studies were also performed with neutralizing anti-TGF-beta Abs, soluble antagonists (soluble TGF-betaR-Fc), and Tg mice (Smad3-/- and TGF-betaRII-Fc Tg) that have disruptions in all or part of the TGF-beta signaling cascade. In all cases, fibrosis developed normally and with kinetics similar to wild-type mice. Production of IL-13 was also unaffected. Finally, several genes, including interstitial collagens, several MMPs, and tissue inhibitors of metalloprotease-1 were up-regulated in TGF-beta1-/- mice by IL-13, demonstrating that IL-13 activates the fibrogenic machinery directly. Together, these studies provide unequivocal evidence of a pathway of fibrogenesis that is IL-13 dependent but TGF-beta1 independent, illustrating the importance of targeting IL-13 directly in the treatment of infection-induced fibrosis.

Animals↗
PubMed1990

[Use of molecular and genetic approaches in prenatal diagnosis and prevention of hemophilia A and Duchenne muscular dystrophy].

Allele polymorphism has been evaluated using blot hybridization and a polymerase cascade of DNA synthesis in 40 families at high risk of hemophilia A (a total of 147 subjects) and in 15 families with Duchenne's myodystrophy, Heterozygous carriage of hemophilia A was identified or confirmed in 18 and ruled out in 4 close female relatives of probands. Prenatal tests for fetal hemophilia A were performed in 5 women from families with hemophilia A (in the 1st trimester in 2 and in the 2nd trimester in 3). Four diagnoses of hemophilia A were confirmed and 1 was ruled out. The DNA methods proved revealing in 34 of 40 families with hemophilia A and in 11 of 15 families with Duchenne's myodystrophy. Three of 9 probands were found to have a deletion of the proximal gene for Duchenne's myodystrophy in the DNA probe area of XY 1.1. Prospects of screening for heterozygous carriage and prenatal identification of hemophilia A and Duchenne's myodystrophy are discussed.

Chorionic Villi Sampling↗
PubMed1986

Homologous species restriction in lysis of human erythrocytes: a membrane-derived protein with C8-binding capacity functions as an inhibitor.

An intrinsic membrane protein with a m.w. of 65,000 that can bind human C8 has been identified after separation of human erythrocyte membrane proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrotransfer to nitrocellulose sheets. The protein, tentatively designated as the C8-binding protein (C8bp) could be isolated from papain-treated erythrocyte (E) membranes by phenol-water extraction and isoelectric focusing. In a functional assay, with chicken (ch) E as target cells, C8bp inhibited the lysis of ch E C5b67 intermediates by human C8 and C9, whereas the lysis by rabbit C8 and C9 was not affected. Because the decay accelerating factor (DAF) from human erythrocyte membranes also inhibits the activity of C3/C5 convertases in an homologous system, we tested whether or not a DAF activity was present in C8bp. C8bp, however, did not accelerate the decay of the classic C3 convertases. Thus, it appears that C8bp and DAF are two different factors of E membranes with a similar molecular size inhibiting different sites of the activation cascade of complement while they can function synergistically to minimize the self-inflicted damage by complement.

Blood Proteins↗
PubMed2001

Differential activation of mitogen-activated protein kinase cascades and apoptosis by protein kinase C epsilon and delta in neonatal rat ventricular myocytes.

Protein kinase C (PKC) epsilon and PKCdelta translocation in neonatal rat ventricular myocytes (NRVMs) is accompanied by subsequent activation of the ERK, JNK, and p38(MAPK) cascades; however, it is not known if either or both novel PKCs are necessary for their downstream activation. Use of PKC inhibitors to answer this question is complicated by a lack of isoenzyme specificity, and the fact that many PKC inhibitors stimulate JNK and p38(MAPK) activity. Therefore, replication-defective adenoviruses (Advs) encoding constitutively active (ca) mutants of PKCepsilon and PKCdelta were used to test if either or both of these PKCs are sufficient to activate ERKs, JNKs, and/or p38(MAPK) in NRVMs. Adv-caPKCepsilon infection (1 to 25 multiplicities of viral infection (MOI); 4 to 48 hours) increased total PKCepsilon levels in a time- and dose-dependent manner, with maximal expression observed 8 hours after Adv infection. Adv-caPKCepsilon induced a time- and dose-dependent increase in phosphorylated p42 and p44 ERKs, as compared with a control Adv encoding beta-galactosidase (Adv-nebetagal). Maximal ERK phosphorylation occurred 8 hours after Adv infection. In contrast, JNK was only minimally activated, and p38(MAPK) was relatively unaffected. Adv-caPKCdelta infection (1 to 25 MOI, 4 to 48 hours) increased total PKCdelta levels in a similar fashion. Adv-caPKCdelta (5 MOI) induced a 29-fold increase in phosphorylated p54 JNK, and a 15-fold increase in phosphorylated p38(MAPK) 24 hours after Adv infection. In contrast, p42 and p44 ERK were only minimally activated. Whereas neither Adv induced NRVM hypertrophy, Adv-caPKCdelta, but not Adv-caPKCepsilon, induced NRVM apoptosis. We conclude that the novel PKCs differentially regulate MAPK cascades and apoptosis in an isoenzyme-specific and time-dependent manner.

Adenoviridae↗
PubMed1997

Immunocytochemical localization of testis ecdysiotropin in the pupa of the gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae).

Antiserum against testis ecdysiotropin isolated from the gypsy moth, Lymantria dispar, reacted with neurons in the protocerebrum, optic and antennal lobes, subesophageal, thoracic and abdominal ganglia, as well as in nerve tracts extending through the optic lobes, tritocerebrum, and interganglionic connectives of the pupal stage of these insects. Testis ecdysiotropin is a peptide required by immature moths to initiate production of testes ecdysteroid, which is necessary for the development of the male reproductive system and initiation of spermatogenesis. Antiserum against testis ecdysiotropin also detected an accumulation of testis ecdysiotripic-like material between the inner and outer testis sheaths of pupae. The localization of this peptide in the imaginal disks of the last larval stage, cells and nerve fibers in the optic and antennal lobes of the pupa of both sexes, as well as in the testes during development of the adult reproductive system indicates that testis ecdysiotropin has a much larger impact on adult metamorphosis than development of the reproductive system and initiation of gametogenesis. Although this peptide may have a modulatory role in the central nervous system (CNS), it may also initiate a cascade of activity required for the development of the adult nervous system, in addition to its role in reproduction.

Abdomen↗
PubMed2002

The tomato dark green mutation is a novel allele of the tomato homolog of the DEETIOLATED1 gene.

A comprehensive, multi-generation, allele test, carried out in this study, suggests that the tomato mutations dark-green (dg) and high pigment 2(j) (hp-2(j)) are allelic. The hp-2(j) mutant is caused by a mutation in the tomato homolog of the DEETIOLATED1 (DET1) gene, involved in the signal transduction cascade of light perception and morphogenesis. This suggestion is in agreement with the exaggerated photomorphogenic de-etiolation response of homozygous dg mutants grown under modulated light conditions. Sequence analysis of the DET1 gene was carried out in dg mutants representing two different lines, and revealed a single A-to-T base transversion in the second exon of the DET1 gene in comparison with the normal wild-type sequence. This transversion results in a conserved Asparagine(34)-to-Isoleucine(34) amino-acid substitution, and eliminates a recognition site for the AclI restriction endonuclease, present in the wild-type and in the other currently known tomato mutants at the DET1 locus. This polymorphism was used to develop a PCR-based DNA marker, which enables an early genotypic selection for breeding lycopene-rich tomatoes. Using this marker and sequence analysis we demonstrate that an identical base transversion also exists in dg mutants of the cultivar Manapal, in which the natural dg mutation was originally discovered. A linkage analysis, carried out in a F(2) population, shows a very strong linkage association between the DET1 locus of dg mutant plants and the photomorphogenic response of the seedlings, measured as hypocotyl length (12 < LOD Score < 13, R(2) = 51.1%). The results presented in this study strongly support the hypothesis that the tomato dg mutation is a novel allele of the tomato homolog of the DET1 gene.

Alleles↗
PubMed1993

The CASCADE Study: randomized antiarrhythmic drug therapy in survivors of cardiac arrest in Seattle. CASCADE Investigators.

The Cardiac Arrest in Seattle: Conventional Versus Amiodarone Drug Evaluation (CASCADE) study evaluated antiarrhythmic drug therapy in patients who had survived an episode of out-of-hospital ventricular fibrillation (VF) and who were thought to be at high risk for recurrence of VF. Therapy with empiric amiodarone was compared to therapy with other antiarrhythmic agents, guided by electrophysiologic testing and/or Holter recording. The study evaluated the endpoints of (1) cardiac death, (2) cardiac arrest from ventricular fibrillation with resuscitation, and (3) complete syncope followed by a shock from an automatic implanted defibrillator that restored consciousness. The study comprised 228 patients, 113 treated with amiodarone and 115 treated with conventional antiarrhythmic drug therapy. Most patients had coronary artery disease with a prior myocardial infarction, and one half of the population had a history of congestive heart failure. The mean left ventricular ejection fraction was 35%. Survival was better in patients treated with amiodarone than in patients treated with other antiarrhythmic agents. Patients treated with amiodarone were less likely to receive a shock from an implanted defibrillator, and syncope followed by a shock from a defibrillator was less common in patients treated with amiodarone. However, overall mortality was high, and side effects of therapy were common. Patients treated with amiodarone, even at the low doses used in this study, were still at risk for thyroid dysfunction (both hyperthyroidism and hypothyroidism) and for pulmonary toxicity.

Aged↗
PubMed2005

Downregulation of inhibitor of apoptosis proteins in apoptotic human chondrocytes treated with tumor necrosis factor-alpha and actinomycin D.

OBJECTIVE: Apoptosis of chondrocytes plays a pivotal role in cartilage degeneration. Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine and has been assumed to cause the degradation of human cartilage. To investigate the mechanisms of TNF-alpha-mediated apoptosis of human chondrocytes from a point of view of the balance between the caspase-cascade and the expression of inhibitor of apoptosis proteins (IAPs), although both of them are induced with TNF-signals. METHODS: The expression of TNF-receptors (TNF-Rs) in normal human articular chondrocyte (NHAC-kn) was examined with immunocytochemistry. Subconfluent cultures of NHAC-kn were tested with TNF-alpha and/or actinomycin D (actD), and the induction of apoptosis was evaluated by the frequency of apoptotic cells visualized with nuclear staining using Hoechst 33342. The activation of caspases and the expression of IAPs were examined with Western blot analyses. RESULTS: NHAC-kn expressed TNF-R1 and -R2. When NHAC-kn was treated with TNF-alpha (10 ng/ml) and actD (0.2 microg/ml) for 24 h, the frequency of apoptotic cells increased to more than 25%. TNF-alpha alone, however, induced the apoptosis insufficiently (up to 8.3%), even when used at the concentration of 100 ng/ml for 48 h. In apoptotic human chondrocytes induced with TNF-alpha (10 ng/ml) and actD (0.2 microg/ml), the caspase-3, -8, and -9 were activated and the protein expression of XIAP and c-IAP1 decreased. CONCLUSIONS: In apoptotic human chondrocytes induced with TNF-alpha and actD, the balance between caspase activation and IAPs' expression lay with the executioner caspase (caspase-3) and led to decreased expression of XIAP and c-IAP1.

Apoptosis↗
PubMed1998

Effect of aescine on hypoxia-induced neutrophil adherence to umbilical vein endothelium.

Although venous stasis due to blood stagnation in lower limbs has been recognised as an important etiological factor for the development of varicose veins, the mechanism linking this ischemic situation to the modifications of the venous wall in varicose veins is still unclear. There is evidence that the activation of the endothelium during blood stasis and its subsequent cascade of interactions with other cell types could alter the structure of the vein wall and could possibly be at the origin of the disease. While phlebotonic drugs are often used to improve symptoms in chronic venous insufficiency, their precise mechanism of action is not well understood. We now tested aescine (Reparil i.v. form) in an ex vivo model which mimics this situation, i.e., perfused human umbilical vein exposed to hypoxic conditions. To study the effect of aescine on neutrophil activation and adhesion to the endothelium, human umbilical veins were incubated under hypoxic conditions with or without aescine and the interactions between the endothelium and neutrophil-like cells, HL60, were investigated. We observed that a large number of HL60 became adherent to the endothelium of veins after 2 h hypoxia and that these adherent HL60 were activated: they released high amounts of superoxide anion and of leukotriene B4. Aescine (250 ng/ml or 0.22 microM) was shown to markedly inhibit HL60 adherence to hypoxic endothelium. By decreasing the number of adherent HL60, aescine also decreased the subsequent production of superoxide anion and of leukotriene B4. Scanning electron microscopy confirmed the increased HL60 adherence to the endothelium, as well as the inhibitory effect of aescine. These results support results of in vitro studies on isolated endothelial cells in which aescine was shown to inhibit the hypoxia-induced activation of endothelial cells and the subsequent increased adherence of neutrophils. In vivo, the activated and infiltrated leukocytes release free radicals, chemotactic molecules such as leukotriene B4 and proteases which then can degrade the extracellular matrix. These processes could contribute to alterations of the venous wall similar to those observed in varicose veins. By maintaining an intact endothelium during in vivo blood stasis in the lower limbs and preventing neutrophil recruitment, adherence and activation, aescine could prevent the resulting alterations of the venous wall. These results could explain at least in part the potential benefit of the drug in the prevention of venous insufficiency.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

Paradoxical activation of Raf by a novel Raf inhibitor.

BACKGROUND: Raf is a proto-oncogene that is activated in response to growth factors or phorbol esters, and is thought to activate MAP kinase kinase-1 (MKK1) and hence the classical MAP kinase (MAPK) cascade. RESULTS: The compound ZM 336372 is identified as a potent and specific inhibitor of Raf isoforms in vitro. Paradoxically, exposure of cells to ZM 336372 induces > 100-fold activation of c-Raf (measured in the absence of compound), but without triggering any activation of MKK1 or p42 MAPK/ERK2. The ZM 336372-induced activation of c-Raf occurs without any increase in the GTP-loading of Ras and is not prevented by inhibition of the MAPK cascade, protein kinase C or phosphatidylinositide 3-kinase. ZM 336372 does not prevent growth factor or phorbol ester induced activation of MKK1 or p42 MAPK/ERK2, or reverse the phenotype of Ras- or Raf-transformed cell lines. The only other protein kinase inhibited by ZM 336372 out of 20 tested was SAPK2/p38. Although ZM 336372 is structurally unrelated to SB 203580, a potent inhibitor of SAPK2/p38, the mutation of Thr106-->Met made SAPK2/p38 insensitive to ZM 336372 as well as to SB 203580. CONCLUSIONS: Raf appears to suppress its own activation by a novel feedback loop, such that inhibition is always counterbalanced by reactivation. These observations imply that some agonists reported to trigger the cellular activation of c-Raf might actually be inhibitors of this enzyme, and that compounds which inhibit the kinase activity of Raf might not be useful as anticancer drugs. The binding sites for ZM 336372 and SB 203580 on Raf and SAPK2/p38 are likely to overlap.

3T3 Cells↗
PubMed2000

The cognate facilitation effect: implications for models of lexical access.

Do nonselected lexical nodes activate their phonological information? Catalan-Spanish bilinguals were asked to name (a) pictures whose names are cognates in the 2 languages (words that are phonologically similar in the 2 languages) and (b) pictures whose names are noncognates in the 2 languages. If nonselected lexical nodes are phonologically encoded, naming latencies should be shorter for cognate words, and because the cognate status of words is only meaningful for bilingual speakers, this difference should disappear when testing monolingual speakers. The results of Experiment 1 fully supported these predictions. In Experiment 2, the difference between cognate and noncognate words was larger when naming in the nondominant language than when naming in the dominant language. The results of the 2 experiments are interpreted as providing support to cascaded activation models of lexical access.

Adolescent↗
PubMed2005

Studying individual aging in an interindividual context: typical paths of age-related, dementia-related, and mortality-related cognitive development in old age.

This study has 2 objectives: (a) to explore typical paths of cognitive development associated with aging, terminal decline, and dementia and (b) to promote and illustrate an individual-oriented approach to the study of cognitive aging based on longitudinal panel data from a population-based sample (N = 500; age range-sub(T1)= 60-80, where T refers to time) tested at 3 occasions 5 years apart. Results document interindividual differences in multivariate patterns of change. Although cognitive changes generally covary, the present study indicates that subgroups of individuals develop along different paths characterized by selective changes in subsets of cognitive functions. Typical progression of dementia followed a developmental cascade from low declarative memory, via low functioning across all observed cognitive measures, to dementia diagnosis, and finally, death.

Aged↗
PubMed2002

Extracorporeal photopheresis in cutaneous T-cell lymphoma and graft-versus-host disease induces both immediate and progressive apoptotic processes.

BACKGROUND: Extracorporeal photopheresis (ECP) therapy is used in the treatment of many T-cell-mediated conditions including cutaneous T-cell lymphoma and graft-versus-host disease and involves the reinfusion of a patient's own white cells following exposure to 8-methoxypsoralen and ultraviolet A. ECP has been demonstrated to induce significant levels of apoptosis in treated lymphocytes. Previous work has highlighted the importance of mitochondria and the caspase cascade in the regulation and execution of apoptosis and, more recently, a functional role for CD10 has been proposed for apoptotic lymphoid cells in vivo. OBJECTIVES: To determine the effect of ECP on phosphatidylserine (PS) exposure, mitochondrial function, caspase activation and CD10 expression of treated lymphocytes. METHODS: Lymphocytes were tested pre-ECP and at several stages post-ECP for changes to PS, mitochondrial transmembrane potential (DeltaPsim), activated caspases and CD10 expression. RESULTS: Early apoptosis induced a disruption in DeltaPsim, while caspase activation was not observed until 24 h post-ECP. CD10 expression was very weak and "late" in the apoptotic process. CONCLUSIONS: The early induction of apoptosis by ECP involves mitochondrial dysfunction, while later apoptosis is associated with the activation of caspases. CD10 expression was very weak and "late", preceded by a strong PS exposure. These apoptotic processes, in vivo, would induce the immediate and progressive phagocytosis of the majority of ECP-treated lymphocytes within 48 h.

Apoptosis↗
PubMed1999

The carboxyl-terminal domains of gp130-related cytokine receptors are necessary for suppressing embryonic stem cell differentiation. Involvement of STAT3.

Cell type-specific responses to the leukemia inhibitory factor (LIF)/interleukin 6 cytokine family are mediated by dimerization of the LIF receptor alpha-chain (LIFRalpha) with the signal transducer gp130 or of two gp130 molecules followed by activation of the JAK/STAT and Ras/mitogen-activated protein kinase cascades. In order to dissect the contribution of gp130 and LIFRalpha individually, chimeric molecules consisting of the extracellular domain of the granulocyte colony stimulating factor receptor (GCSF-R) and various mutant forms of the cytoplasmic domains of gp130 or LIFRalpha were expressed in embryonic stem (ES) cells to test for suppression of differentiation, or in a factor-dependent plasma cytoma cell line to assess for induction of proliferation. Carboxyl-terminal domains downstream of the phosphatase (SHP2)-binding sites were dispensable for mitogen-activated protein kinase activation and the transduction of proliferative signals. Moreover, carboxyl-terminal truncation mutants which lacked intact Box 3 homology domains showed decreased STAT3 activation, failed to induce Hck kinase activity and suppress ES cell differentiation. Moreover, STAT3 antisense oligonucleotides impaired LIF-dependent inhibition of differentiation. Substitution of the tyrosine residue within the Box 3 region of the GSCF-R abolished receptor-mediated suppression of differentiation without affecting the transduction of proliferative signals. Thus, distinct cytoplasmic domains within the LIFRalpha, gp130, and GCSF-R transduce proliferative and differentiation suppressing signals.

Antigens, CD↗
PubMed2005

Hahb-10, a sunflower homeobox-leucine zipper gene, is regulated by light quality and quantity, and promotes early flowering when expressed in Arabidopsis.

Homeodomain-leucine zipper proteins constitute a family of transcription factors found only in plants. Expression patterns of the sunflower homeobox-leucine zipper gene Hahb-10 (Helianthus annuus homeobox-10), that belongs to the HD-Zip II subfamily, were analysed. Northern blots showed that Hahb-10 is expressed primarily in mature leaves, although expression is clearly detectable in younger leaves and also in stems. Considerably higher expression levels were detected in etiolated seedlings compared with light-grown seedlings. Induction of Hahb-10 expression was observed when seedlings were subjected to treatment with gibberellins. Transgenic Arabidopsis thaliana plants that express Hahb-10 under the 35S cauliflower mosaic virus promoter show special phenotypic characteristics such as darker cotyledons and planar leaves. A reduction in the life cycle of about 25% allowing earlier seed collection was also observed, and this phenomenon is clearly related to a shortened flowering time. When the number of plants per pot increased, the difference in developmental rate between transgenic and non-transformed individuals became larger. After gibberellin treatment, the relative difference in life cycle duration was considerably reduced. Several light-regulated genes have been tested as possible target genes of Hahb-10. One of them, PsbS, shows a different response to illumination conditions in transgenic plants compared with the response in wild-type plants while the other genes behave similarly in both genotypes. We propose that Hahb-10 functions in a signalling cascade(s) that control(s) plant responses to light quality and quantity, and may also be involved in gibberellin transduction pathways.

Arabidopsis↗
PubMed2002

Hepatitis C virus core protein expression in human B-cell lines does not significantly modify main proliferative and apoptosis pathways.

Hepatitis C virus (HCV) chronic infection has been associated with many lymphoproliferative disorders. Several studies performed on hepatoma and fibroblast cell lines suggest a role of the HCV core protein in activation of cellular transduction pathways that lead to cell proliferation and inhibition of apoptosis. However, no data are available concerning the effects of HCV core expression on B-lymphocyte proliferation and apoptosis. B-lymphocyte cell lines permanently expressing full-length HCV 1b core sequences isolated from chronically infected patients were established using B-cell lines at different degrees of differentiation. Clones and pools of clones permanently expressing the HCV core were selected and characterized for protein expression by Western blot and FACS. Expression of HCV core proteins did not significantly enhance cell proliferation rates under normal culture conditions or under mitogenic stimulation. Analysis of NF-kappa B, CRE, TRE and SRE pathways by luciferase reporter genes did not show a significant influence of HCV core expression on these signal transduction cascades in B-lymphocytes. The effects of HCV core on anti-IgM and anti-FAS-induced apoptosis in B-cell lines was also analysed. In this experimental model, HCV core expression did not significantly modify the apoptotic profile of the B-lymphocyte cell lines tested. These data underline a cell type-specific effect of HCV core expression. In fact, it was not possible to show a significant contribution of the HCV core protein in activation of the major B-cell signal transduction pathways involved in the regulation of proliferation and programmed cell death, which is in contrast with the results reported in hepatoma cell lines.

Antibodies, Anti-Idiotypic↗