Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 31
Filter
1.
Brachytherapy ; 16(1): 201-206, 2017.
Article in English | MEDLINE | ID: mdl-27919653

ABSTRACT

PURPOSE: Multiparametric MRI (mpMRI) has a potential role for the identification of aggressive cancer that can be targeted for biopsy. We report the incidence and severity of discordant information between the pathology found on the transrectal ultrasound (TRUS)-guided biopsy and the mpMRI findings in patients with favorable or intermediate-risk prostate cancer referred for brachytherapy. METHODS AND MATERIALS: From March 2014 to September 2015, 10/44 consecutive patients with low- or intermediate-risk prostate cancer referred for brachytherapy presented an aggressive lesion on mpMRI and underwent an MRI-TRUS fusion-guided transperineal biopsy of the index lesion. RESULTS: A median of two intraprostatic lesions were detected by mpMRI for each patient. Three patients had bilateral disease, and seven had unilateral disease on mpMRI. The median number of cores obtained by MRI-TRUS-guided fusion of the index lesion was 3 (range 2-4). As a result of the re-evaluation consequent to additional information becoming available after the transperineal biopsy, upgrading of Gleason score occurred in 8 of the 10 patients, which changed the risk group in 9 patients. These changes resulted in modification of the proposed treatment in 8 patients. CONCLUSIONS: MpMRI-US fusion-targeted biopsy sampling allows detection and characterization of otherwise undetected aggressive disease, often placing men in higher risk groups and altering the treatment approach.


Subject(s)
Adenocarcinoma/pathology , Prostatic Neoplasms/pathology , Adenocarcinoma/diagnostic imaging , Adenocarcinoma/radiotherapy , Aged , Biopsy, Large-Core Needle , Brachytherapy , Endosonography , Humans , Image-Guided Biopsy , Magnetic Resonance Imaging , Male , Neoplasm Grading , Prostatic Neoplasms/diagnostic imaging , Prostatic Neoplasms/radiotherapy
2.
Ann Rheum Dis ; 69(1): 241-8, 2010 Jan.
Article in English | MEDLINE | ID: mdl-19124525

ABSTRACT

OBJECTIVES: Adult mesenchymal stem cells were recently found to suppress effector T cell and inflammatory responses and have emerged as attractive therapeutic candidates for immune disorders. In rheumatoid arthritis (RA), a loss in the immunological self-tolerance causes the activation of autoreactive T cells against joint components and subsequent chronic inflammation. The aim of this study is to characterise the immunosuppressive activity of human adipose-derived mesenchymal stem cells (hASCs) on collagen-reactive T cells from patients with RA. METHODS: The effects of hASCs on collagen-reactive RA human T cell proliferation and cytokine production were investigated, as well as effects on the production of inflammatory mediators by monocytes and fibroblast-like synoviocytes from patients with RA. RESULTS: hASCs suppressed the antigen-specific response of T cells from patients with RA. hASCs inhibited the proliferative response and the production of inflammatory cytokines by collagen-activated CD4 and CD8 T cells. In contrast, the numbers of IL10-producing T cells and monocytes were significantly augmented upon hASC treatment. The suppressive activity of hASCs was cell-to-cell contact dependent and independent. hASCs also stimulated the generation of FoxP3 protein-expressing CD4(+)CD25(+) regulatory T cells, with the capacity to suppress collagen-specific T cell responses. Finally, hASCs downregulated the inflammatory response and the production of matrix-degrading enzymes by synovial cells isolated from patients with RA. CONCLUSIONS: The present work identifies hASCs as key regulators of immune tolerance, with the capacity to suppress T cell and inflammatory responses and to induce the generation/activation of antigen-specific regulatory T cells.


Subject(s)
Arthritis, Rheumatoid/immunology , Inflammation Mediators/metabolism , Mesenchymal Stem Cells/immunology , T-Lymphocyte Subsets/immunology , T-Lymphocytes, Regulatory/immunology , Adipose Tissue/immunology , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Cells, Cultured , Female , Humans , Immune Tolerance/immunology , Lymphocyte Activation/immunology , Male
3.
Gut ; 58(7): 929-39, 2009 Jul.
Article in English | MEDLINE | ID: mdl-19136511

ABSTRACT

BACKGROUND AND AIMS: Inflammatory bowel diseases (IBDs) are associated with uncontrolled innate and adaptive immunity against normal constituents, including commensal bacteria and microbial products. Mesenchymal stem cells (MSCs) suppress effector T cell responses and have beneficial effects in various immune disorders. This work investigates the therapeutic effects of human adipose-derived MSCs (hASCs) in various models of IBD and sepsis. METHODS: Acute and chronic colitis was induced in mice with dextran sulfate sodium. Sepsis was induced by caecal ligation and puncture or by endotoxin injection. Colitic and septic mice were treated intraperitoneally with hASCs or murine ASCs, and diverse disease clinical signs and mortality were determined. The levels of various inflammatory cytokines and chemokines, T helper 1(Th1)-type response and generation of regulatory T cells (Treg) were determined in affected organs. RESULTS: Systemic infusion of ASCs significantly ameliorated the clinical and histopathological severity of colitis, abrogating weight loss, diarrhoea and inflammation, and increasing survival. The therapeutic effect was associated with downregulation of the Th1-driven inflammatory responses. ASCs decreased a wide panel of inflammatory cytokines and chemokines and increased interleukin 10 (IL10), acting on macrophages. hASCs also impaired Th1 cell activation in both colonic mucosa and draining lymph nodes. The induction of IL10-secreting Treg was partially involved in the therapeutic effect of hASCs. Moreover, ASCs protected from severe sepsis by reducing the infiltration of inflammatory cells in various target organs and by downregulating the production of various inflammatory mediators. CONCLUSIONS: hASCs emerge as key regulators of immune/inflammatory responses in vivo and as attractive candidates for cell-based treatments for IBD and sepsis.


Subject(s)
Adipose Tissue/cytology , Colitis/surgery , Inflammatory Bowel Diseases/surgery , Mesenchymal Stem Cell Transplantation , Sepsis/surgery , T-Lymphocytes, Regulatory/immunology , Adult Stem Cells/immunology , Animals , Cells, Cultured , Colitis/immunology , Down-Regulation , Endotoxemia/prevention & control , Humans , Inflammatory Bowel Diseases/immunology , Mesenchymal Stem Cells/immunology , Mice , Mice, Inbred C57BL , Sepsis/immunology
4.
Opt Lett ; 27(3): 149-51, 2002 Feb 01.
Article in English | MEDLINE | ID: mdl-18007738

ABSTRACT

Wave-front sensing from artificial beacons is normally performed by formation of a focused spot in the atmosphere and sensing of the wave-front distortions produced during the beam's return passage. We propose an alternative method that senses the distortions produced during the outgoing path by forming an intensity pattern in the atmosphere that is then viewed from the ground. A key advantage of this method is that a parallel beam is used, and therefore the wave-front measurements will not suffer from the effects of focal anisoplanatism. We also envisage other geometries, all based on the concept of projecting a pupil pattern onto the atmosphere.

5.
Cell ; 104(6): 891-900, 2001 Mar 23.
Article in English | MEDLINE | ID: mdl-11290326

ABSTRACT

A regulatory loop between the fibroblast growth factors FGF-8 and FGF-10 plays a key role in limb initiation and AER induction in vertebrate embryos. Here, we show that three WNT factors signaling through beta-catenin act as key regulators of the FGF-8/FGF-10 loop. The Wnt-2b gene is expressed in the intermediate mesoderm and the lateral plate mesoderm in the presumptive chick forelimb region. Cells expressing Wnt-2b are able to induce Fgf-10 and generate an extra limb when implanted into the flank. In the presumptive hindlimb region, another Wnt gene, Wnt-8c, controls Fgf-10 expression, and is also capable of inducing ectopic limb formation in the flank. Finally, we also show that the induction of Fgf-8 in the limb ectoderm by FGF-10 is mediated by the induction of Wnt-3a. Thus, three WNT signals mediated by beta-catenin control both limb initiation and AER induction in the vertebrate embryo.


Subject(s)
Chick Embryo/physiology , Fibroblast Growth Factors/physiology , Limb Buds/physiology , Proto-Oncogene Proteins/physiology , Trans-Activators , Zebrafish Proteins , Animals , Avian Proteins , Cytoskeletal Proteins/physiology , Ectoderm/physiology , Fibroblast Growth Factor 10 , Fibroblast Growth Factor 8 , Fibroblast Growth Factors/genetics , Gene Expression Regulation, Developmental , Mesoderm/physiology , Mitogens/physiology , Morphogenesis , Proto-Oncogene Proteins/chemistry , Proto-Oncogene Proteins/genetics , Signal Transduction , Wings, Animal/embryology , Wnt Proteins , Wnt2 Protein , beta Catenin
6.
FASEB J ; 14(13): 2008-21, 2000 Oct.
Article in English | MEDLINE | ID: mdl-11023985

ABSTRACT

Using immobilized GST-Raf-1 as bait, we have isolated the intermediate filament protein vimentin as a Raf-1-associated protein. Vimentin coimmunoprecipitated and colocalized with Raf-1 in fibroblasts. Vimentin was not a Raf-1 substrate, but was phosphorylated by Raf-1-associated vimentin kinases. We provide evidence for at least two Raf-1-associated vimentin kinases and identified one as casein kinase 2. They are regulated by Raf-1, since the activation status of Raf-1 correlated with the phosphorylation of vimentin. Vimentin phosphorylation by Raf-1 preparations interfered with its polymerization in vitro. A subset of tryptic vimentin phosphopeptides induced by Raf-1 in vitro matched the vimentin phosphopeptides isolated from v-raf-transfected cells labeled with orthophosphoric acid, indicating that Raf-1 also induces vimentin phosphorylation in intact cells. In NIH 3T3 fibroblasts, the selective activation of an estrogen-regulated Raf-1 mutant induced a rearrangement and depolymerization of the reticular vimentin scaffold similar to the changes elicited by serum treatment. The rearrangement of the vimentin network occurred independently of the MEK/ERK pathway. These data identify a new branch point in Raf-1 signaling, which links Raf-1 to changes in the cytoskeletal architecture.


Subject(s)
Intermediate Filaments/ultrastructure , Protein Serine-Threonine Kinases/metabolism , Proto-Oncogene Proteins c-raf/metabolism , Vimentin/metabolism , Amino Acid Sequence , Cells, Cultured , Enzyme Activation , Molecular Sequence Data , Peptide Mapping , Phosphopeptides/isolation & purification , Phosphorylation , Protein Binding
7.
Opt Express ; 7(11): 368-74, 2000 Nov 20.
Article in English | MEDLINE | ID: mdl-19407888

ABSTRACT

We present results of the isoplanatic performance of an astronomical adaptive optics system in the laboratory, by using a dual layer turbulence simulator. We describe how the performance of adaptive correction degrades with off--axis angle. These experiments demonstrate that it is now possible to produce quantifiable multi-layer turbulence in the laboratory as a precursor to constructing multi-conjugate adaptive optics.

9.
Genes Dev ; 13(10): 1322-8, 1999 May 15.
Article in English | MEDLINE | ID: mdl-10346820

ABSTRACT

IkappaB kinases (IKKs) IKK1 and IKK2 are two putative IkappaBalpha kinases involved in NF-kappaB activation. To examine the in vivo functions of IKK1, we generated IKK1-deficient mice. The mutant mice are perinatally lethal and exhibit a wide range of developmental defects. Newborn mutant mice have shiny, taut, and sticky skin without whiskers. Histological analysis shows thicker epidermis, which is unable to differentiate. Limbs and tail are wrapped inside the skin and do not extend properly out of the body trunk. Skeleton staining reveals a cleft secondary palate, split sternebra 6, and deformed incisors. NF-kappaB activation mediated by TNFalpha and IL-1 is diminished in IKK1-deficient mouse embryonic fibroblast (MEF) cells. The IKK complex in the absence of IKK1 is capable of phosphorylating IkappaBalpha and IkappaBbeta in vitro. Our results support a role for IKK1 in NF-kappaB activation and uncover its involvement in skin and skeleton development. We conclude further that the two related kinases IKK1 and IKK2 have distinct functions and can not be substituted for each other's functions.


Subject(s)
Bone and Bones/abnormalities , Protein Serine-Threonine Kinases/physiology , Skin Abnormalities/genetics , Animals , Embryo, Mammalian/anatomy & histology , Epidermis/anatomy & histology , I-kappa B Kinase , Interleukin-1/metabolism , Interleukin-6/metabolism , Mice , Mice, Inbred C57BL , Mice, Transgenic , Mutagenesis , NF-kappa B/metabolism , Phenotype , Time Factors , Tumor Necrosis Factor-alpha/metabolism
10.
Cell Tissue Res ; 296(1): 131-9, 1999 Apr.
Article in English | MEDLINE | ID: mdl-10199973

ABSTRACT

Limb development has become one of the model systems for studying vertebrate development. One crucial aspect in limb development is the origin, differentiation and patterning of muscle. Much progress has been made in recent years towards understanding this process. One of the general observations is that the genes involved in limb muscle development appear to be very similar to those involved in muscle development in other regions of the embryo. In this review, we summarize some of the genes and mechanisms that regulate limb muscle development and discuss various avenues along which a deeper understanding can be gained of how muscle cells originate and differentiate in different tissues during vertebrate development.


Subject(s)
Body Patterning , Extremities/embryology , Muscle, Skeletal/embryology , Vertebrates/embryology , Animals , Cell Differentiation , Gene Expression Regulation, Developmental , Models, Biological , Muscle Proteins/genetics , Muscle, Skeletal/cytology
11.
Curr Top Dev Biol ; 41: 37-66, 1999.
Article in English | MEDLINE | ID: mdl-9784972

ABSTRACT

The body plan is generated by cells and tissues that become arranged precisely in the embryo. This process, termed pattern formation, involves cell interactions in which a particular group of cells produce signals that specify new cell types or patterns of differentiation in responding cells. These patterning signals emanate from very discrete centers called "organizer centers," such as the Hensen's node or Spemann organizer, the midbrain-hindbrain junction, the notochord, or in the case of the limb, the zone of polarizing activity (ZPA) or the apical ectodermal ridge (AER). The developing vertebrate limb is an ideal model system for the study of pattern formation because, in addition to surgical manipulations, molecular manipulations are now feasible. In this review we summarize early experiments that established, by means of surgical manipulations, the different organizer centers of the vertebrate limb: the ectoderm covering the limb bud, the apical ectodermal ridge, the zone of polarizing activity, and the distal mesoderm (progress zone) underlying the AER. We then describe the domains of expression of various genes present during the development of the limb and discuss some of the functional approaches (overexpression and lack of function studies) undertaken to ascertain their role in limb outgrowth. The knowledge acquired in the last few years has had an enormous impact not only on our view of how limbs develop (perhaps now one of the most approachable vertebrate model systems) but also in a more general sense of how the embryo is organized in space and time.


Subject(s)
Body Patterning/genetics , Extremities/embryology , Vertebrates/embryology , Animals , Body Patterning/physiology , Chick Embryo , Ectoderm/cytology , Ectoderm/transplantation , Fibroblast Growth Factors/physiology , Gene Expression Regulation, Developmental , Genes, Homeobox , Mesoderm/transplantation , Vertebrates/genetics
12.
Development ; 125(22): 4417-25, 1998 Nov.
Article in English | MEDLINE | ID: mdl-9778501

ABSTRACT

We have determined that Strong's Luxoid (lstJ) [corrected] mice have a 16 bp deletion in the homeobox region of the Alx-4 gene. This deletion, which leads to a frame shift and a truncation of the Alx-4 protein, could cause the polydactyly phenotype observed in lstJ [corrected] mice. We have cloned the chick homologue of Alx-4 and investigated its expression during limb outgrowth. Chick Alx-4 displays an expression pattern complementary to that of shh, a mediator of polarizing activity in the limb bud. Local application of Sonic hedgehog (Shh) and Fibroblast Growth Factor (FGF), in addition to ectodermal apical ridge removal experiments suggest the existence of a negative feedback loop between Alx-4 and Shh during limb outgrowth. Analysis of polydactylous mutants indicate that the interaction between Alx-4 and Shh is independent of Gli3, a negative regulator of Shh in the limb. Our data suggest the existence of a negative feedback loop between Alx-4 and Shh during vertebrate limb outgrowth.


Subject(s)
Body Patterning , Extremities/embryology , Homeodomain Proteins/genetics , Limb Deformities, Congenital , Nerve Tissue Proteins , Repressor Proteins , Trans-Activators , Xenopus Proteins , Amino Acid Sequence , Animals , Chick Embryo , Cloning, Molecular , DNA-Binding Proteins , Extremities/surgery , Feedback , Fibroblast Growth Factors , Hedgehog Proteins , Kruppel-Like Transcription Factors , Mice , Mice, Mutant Strains , Molecular Sequence Data , Polydactyly/genetics , Proteins , Sequence Analysis, DNA , Sequence Deletion , Sequence Homology, Amino Acid , Species Specificity , Tissue Transplantation , Transcription Factors , Zinc Finger Protein Gli3
14.
Dev Dyn ; 211(1): 88-96, 1998 Jan.
Article in English | MEDLINE | ID: mdl-9438426

ABSTRACT

Gli genes represent a small family, encoding zinc-finger proteins of the Krüppel-type. The family consists of Gli(1), Gli2, and Gli3, all of which are expressed in the developing mouse limb bud. To assess the role of the Gli family and Sonic hedgehog (Shh) in mouse limb development, we compared the expression domains of all three Gli genes and of Shh. Although each Gli gene has its own distinct expression pattern in limb buds, at 10.5-11.5 dpc all three genes were found not to be expressed in the posterior region, the presumptive Shh expression domain. This transient mutually exclusive expression suggested a potential interaction between Gli genes and Shh. To address this matter, we analysed the expression of Gli genes and Shh in two polydactyly mouse mutants, Extra toes (Xt) and Hemimelic-extra toes (Hx) which express Shh ectopically in the anterior region of the limb field. Since Xt mice lack Gli3 expression, the ectopic Shh expression is genetically linked to the absence of Gli3. In Hx mice we found a down-regulation of Gli3 in the anterior region of the limb bud. In both mutants Gli2 expression pattern was not altered, whereas Gli1 expression was anteriorly up-regulated adjacent to the ectopic Shh domain. These results strongly suggest a positive regulation of Gli1 by Shh and a negative interaction between Shh and Gli3.


Subject(s)
Extremities/embryology , Gene Expression Regulation, Developmental/physiology , Nerve Tissue Proteins , Oncogene Proteins/genetics , Proteins/genetics , Repressor Proteins , Trans-Activators , Transcription Factors/genetics , Xenopus Proteins , Animals , Body Patterning/genetics , DNA-Binding Proteins/genetics , Hedgehog Proteins , Kruppel-Like Transcription Factors , Limb Buds , Mice , Mice, Inbred C3H , Mice, Mutant Strains , Polydactyly/embryology , Polydactyly/genetics , RNA, Messenger/analysis , Zinc Finger Protein GLI1 , Zinc Finger Protein Gli2 , Zinc Finger Protein Gli3 , Zinc Fingers
15.
Mech Dev ; 62(2): 175-82, 1997 Mar.
Article in English | MEDLINE | ID: mdl-9152009

ABSTRACT

Sonic hedgehog (Shh) expression in the developing limb is associated with the zone of polarising activity (ZPA), and both are restricted to the posterior part of the limb bud. We show that the expression patterns of Shh and Gli3, a member of the Gli-family believed to function in transcriptional control, appear to be mutually exclusive in limb buds of mouse embryos. In the polydactyly mouse mutant extra toes (Xt), possessing a null mutation of Gli3, Shh is additionally expressed in the anterior region of the limb bud. The transcript of Ptc, the putative receptor for Shh protein, can be detected anteriorly as well. Other genes known to be involved in limb outgrowth and patterning, like Fibroblast growth factor (Fgf), Bone morphogenetic protein (Bmp), and Hoxd are misexpressed in relation to the ectopic Shh expression domain in Xt limb buds. This data suggest that Gli3 is a regulator of Shh expression in mouse limb development.


Subject(s)
Bone Morphogenetic Proteins/metabolism , DNA-Binding Proteins/metabolism , Drosophila Proteins , Extremities/physiology , Fibroblast Growth Factors/metabolism , Gene Expression Regulation, Developmental , Nerve Tissue Proteins , Proteins/metabolism , Repressor Proteins , Trans-Activators , Transcription Factors , Transforming Growth Factor beta , Xenopus Proteins , Animals , Bone Morphogenetic Protein 2 , Bone Morphogenetic Protein 4 , Bone Morphogenetic Protein 7 , Extremities/embryology , Fibroblast Growth Factor 4 , Fibroblast Growth Factor 8 , Growth Substances/metabolism , Hedgehog Proteins , Homeodomain Proteins/metabolism , In Situ Hybridization , Insect Proteins/metabolism , Kruppel-Like Transcription Factors , Membrane Proteins/metabolism , Mice , Mice, Inbred C3H , Mutation , Polydactyly/genetics , Proto-Oncogene Proteins/metabolism , Receptors, Cell Surface , Zinc Finger Protein Gli3
16.
Mol Cell Biol ; 16(11): 5955-63, 1996 Nov.
Article in English | MEDLINE | ID: mdl-8887625

ABSTRACT

Ubiquitously expressed SH2-containing tyrosine phosphatases interact physically with tyrosine kinase receptors or their substrates and relay positive mitogenic signals via the activation of the Ras-mitogen-activated protein kinase (MAPK) pathway. Conversely, the structurally related phosphatase SHP-1 is predominantly expressed in hemopoietic cells and becomes tyrosine phosphorylated upon colony-stimulating factor 1 treatment of macrophages without associating with the colony-stimulating factor 1 receptor tyrosine kinase. Mice lacking functional SHP-1 (me/me and me(v)/me(v)) develop systemic autoimmune disease with accumulation of macrophages, suggesting that SHP-1 may be a negative regulator of hemopoietic cell growth. By using macrophages expressing dominant negative Ras and the me(v)/me(v) mouse mutant, we show that SHP-1 is activated in the course of mitogenic signal transduction in a Ras-dependent manner and that its activity is necessary for the Ras-dependent activation of the MAPK pathway but not of the Raf-1 kinase. Consistent with a role for SHP-1 as an intermediate between Ras and the MEK-MAPK pathway, Ras-independent activation of the latter kinases by bacterial lipopolysaccharide occurred normally in me(v)/me(v) cells. Our results sharply accentuate the diversity of signal transduction in mammalian cells, in which the same signaling intermediates can be rearranged to form different pathways.


Subject(s)
Calcium-Calmodulin-Dependent Protein Kinases/metabolism , Hematopoietic Stem Cells/metabolism , Macrophages/physiology , Protein Tyrosine Phosphatases/metabolism , Proto-Oncogene Proteins p21(ras)/metabolism , Signal Transduction , Animals , Enzyme Activation , Guanosine Triphosphate/metabolism , Intracellular Signaling Peptides and Proteins , Lipopolysaccharides/pharmacology , Macrophage Colony-Stimulating Factor/pharmacology , Macrophages/drug effects , Mammals , Mice , Mice, Inbred C57BL , Mice, Mutant Strains , Models, Biological , Phosphotyrosine/metabolism , Protein Serine-Threonine Kinases/metabolism , Protein Tyrosine Phosphatase, Non-Receptor Type 11 , Protein Tyrosine Phosphatase, Non-Receptor Type 6 , Protein Tyrosine Phosphatases/deficiency , Protein Tyrosine Phosphatases/genetics , Proto-Oncogene Proteins/metabolism , Proto-Oncogene Proteins c-raf
17.
Biochim Biophys Acta ; 1307(3): 267-9, 1996 Jul 17.
Article in English | MEDLINE | ID: mdl-8688459

ABSTRACT

The zinc finger gene Gli3 plays a role in limb and brain development. To facilitate the molecular analysis of different mouse mutations of this gene, the murine cDNA was isolated and sequenced. This 5113 bp cDNA encodes a putative protein of 1596 amino acids. Comparison of the murine and human GLI3 cDNA revealed an overall homology of 85% between the deduced amino acid sequences. More importantly, several regions of the protein, including the zinc fingers, are more highly conserved ( > 95%), suggesting that these represent functional domains in the Gli3 protein.


Subject(s)
DNA, Complementary/chemistry , DNA-Binding Proteins/genetics , Nerve Tissue Proteins , Repressor Proteins , Transcription Factors/genetics , Xenopus Proteins , Amino Acid Sequence , Animals , Base Sequence , Cloning, Molecular , DNA-Binding Proteins/chemistry , Humans , Kruppel-Like Transcription Factors , Mice , Molecular Sequence Data , Zinc Finger Protein Gli3
18.
Oncogene ; 10(6): 1187-92, 1995 Mar 16.
Article in English | MEDLINE | ID: mdl-7700643

ABSTRACT

Many tyrosine kinase growth factor receptors activate the MAP Kinase (MAPK) pathway by stimulating the activity of the RAF kinase. In some, but not all cell types, the expression of activated RAF is sufficient to induce constitutive MAPK activation. In BAC-1.2F5 macrophages the expression of virally activated RAF does not correlate with constitutive MAPK activation; on the contrary, growth factor-mediated stimulation of MAPK activity is suppressed in these cells. Suppression correlates with v-RAF expression, as MAPK activation is normal in a revertant cell line that stopped expressing v-RAF. Inhibition of MAPK activation is associated with lack of ERK-2 tyrosine phosphorylation, and is not due to the suppression of CSF-1-mediated MEK activation. Pretreatment with vanadate restores growth factor-stimulated activation and tyrosine phosphorylation of MAPK in v-RAF-expressing macrophages, indicating the involvement of a tyrosine phosphatase. Interestingly, v-RAF-expressing macrophages contain low constitutive levels of MKP-1 mRNA, an immediate early gene that encodes a MAPK-specific phosphatase and is induced in the parental cell line by CSF-1 treatment. The restoration of MAPK activation by vanadate pretreatment and the presence of MKP-1 mRNA in v-RAF-expressing macrophages raise the intriguing possibility that in macrophages RAF may be feeding back on the MAPK pathway by participating in the control of MKP-1 expression.


Subject(s)
Cell Cycle Proteins , Immediate-Early Proteins/metabolism , Macrophages/metabolism , Phosphoprotein Phosphatases , Protein Kinases/metabolism , Protein Tyrosine Phosphatases/metabolism , Retroviridae Proteins, Oncogenic/physiology , Amino Acid Sequence , Cell Line , Dual Specificity Phosphatase 1 , Enzyme Activation , Gene Expression Regulation/drug effects , Immediate-Early Proteins/genetics , Macrophage Colony-Stimulating Factor/pharmacology , Macrophages/enzymology , Molecular Sequence Data , Oncogene Proteins v-raf , Phosphorylation , Protein Phosphatase 1 , Protein Serine-Threonine Kinases/metabolism , Protein Tyrosine Phosphatases/genetics , Retroviridae Proteins, Oncogenic/genetics , Tyrosine/metabolism
19.
Mol Cell Biol ; 15(1): 466-75, 1995 Jan.
Article in English | MEDLINE | ID: mdl-7799956

ABSTRACT

Mitogen-activated protein kinases (MAPKs) are activated upon a variety of extracellular stimuli in different cells. In macrophages, colony-stimulating factor 1 (CSF-1) stimulates proliferation, while bacterial lipopolysaccharide (LPS) inhibits cell growth and causes differentiation and activation. Both CSF-1 and LPS rapidly activate the MAPK network and induce the phosphorylation of two distinct ternary complex factors (TCFs), TCF/Elk and TCF/SAP. CSF-1, but not LPS, stimulated the formation of p21ras. GTP complexes. Expression of a dominant negative ras mutant reduced, but did not abolish, CSF-1-mediated stimulation of MEK and MAPK. In contrast, activation of the MEK kinase Raf-1 was Ras independent. Treatment with the phosphatidylcholine-specific phospholipase C inhibitor D609 suppressed LPS-mediated, but not CSF-1-mediated, activation of Raf-1, MEK, and MAPK. Similarly, down-regulation or inhibition of protein kinase C blocked MEK and MAPK induction by LPS but not that by CSF-1. Phorbol 12-myristate 13-acetate pretreatment led to the sustained activation of the Raf-1 kinase but not that of MEK and MAPK. Thus, activated Raf-1 alone does not support MEK/MAPK activation in macrophages. Phosphorylation of TCF/Elk but not that of TCF/SAP was blocked by all treatments that interfered with MAPK activation, implying that TCF/SAP was targeted by a MAPK-independent pathway. Therefore, CSF-1 and LPS target the MAPK network by two alternative pathways, both of which induce Raf-1 activation. The mitogenic pathway depends on Ras activity, while the differentiation signal relies on protein kinase C and phosphatidylcholine-specific phospholipase C activation.


Subject(s)
Calcium-Calmodulin-Dependent Protein Kinases/metabolism , Lipopolysaccharides/pharmacology , MAP Kinase Kinase Kinase 1 , Macrophage Colony-Stimulating Factor/pharmacology , Macrophages/enzymology , Mitogen-Activated Protein Kinases , Protein Serine-Threonine Kinases , Proto-Oncogene Proteins p21(ras)/metabolism , Signal Transduction , Transcription Factors , Amino Acid Sequence , Animals , Bridged-Ring Compounds/pharmacology , Cells, Cultured , DNA-Binding Proteins/metabolism , Enzyme Activation , Guanosine Triphosphate/metabolism , In Vitro Techniques , Indoles/pharmacology , Maleimides/pharmacology , Mice , Mitogen-Activated Protein Kinase 1 , Mitogen-Activated Protein Kinase 3 , Molecular Sequence Data , Norbornanes , Peptides/chemistry , Phosphorylation , Protein Kinase C/metabolism , Protein-Tyrosine Kinases/metabolism , Proto-Oncogene Proteins/metabolism , Proto-Oncogene Proteins c-raf , Thiocarbamates , Thiones/pharmacology , Type C Phospholipases/metabolism , ets-Domain Protein Elk-1
20.
Appl Opt ; 34(6): 1081-96, 1995 Feb 20.
Article in English | MEDLINE | ID: mdl-21037637

ABSTRACT

We have measured power spectra of atmospheric phase fluctuations with the Mark III stellar interferometer on Mt. Wilson under a wide variety of seeing conditions. On almost all nights, the high-frequency portions of the temporal power spectra closely follow the form predicted by the standard Kolmogorov-Tatarski model. At lower frequencies, a variety of behavior is observed. On a few nights, the spectra clearly exhibit the low-frequency flattening characteristic of turbulence with an outer-scale length of the order of 30 m. On other nights, examination of individual spectra yields no strong evidence of an outer scale less than a few kilometers in size, but comparison of the spectra on different interferometer baselines shows a saturation of the spatial structure function on long baselines. This saturation is consistent with the assumption of an outer-scale length similar to that derived for the nights when low-frequency flattening of the spectra is clearly seen. We discuss possible explanations of this behavior and conclude that power spectra from a single interferometer baseline are a poor diagnostic for the effective outer scale compared with multiple-baseline spectra.

SELECTION OF CITATIONS
SEARCH DETAIL
...