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Ramsden CE, Faurot KR, Zamora D, Suchindran CM, MacIntosh BA, Gaylord S, Ringel A, Hibbeln JR, Feldstein AE, Mori TA, Barden A, Lynch C, Coble R, Mas E, Palsson O, Barrow DA, Mann DJ. Targeted alteration of dietary n-3 and n-6 fatty acids for the treatment of chronic headaches: a randomized trial. Pain 2013; 154:2441-2451. [PMID: 23886520 DOI: 10.1016/j.pain.2013.07.028] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 07/11/2013] [Accepted: 07/17/2013] [Indexed: 12/21/2022]
Abstract
Omega-3 and n-6 fatty acids are biosynthetic precursors to lipid mediators with antinociceptive and pronociceptive properties. We conducted a randomized, single-blinded, parallel-group clinical trial to assess clinical and biochemical effects of targeted alteration in dietary n-3 and n-6 fatty acids for treatment of chronic headaches. After a 4-week preintervention phase, ambulatory patients with chronic daily headache undergoing usual care were randomized to 1 of 2 intensive, food-based 12-week dietary interventions: a high n-3 plus low n-6 (H3-L6) intervention, or a low n-6 (L6) intervention. Clinical outcomes included the Headache Impact Test (HIT-6, primary clinical outcome), Headache Days per month, and Headache Hours per day. Biochemical outcomes included the erythrocyte n-6 in highly unsaturated fatty acids (HUFA) score (primary biochemical outcome) and bioactive n-3 and n-6 derivatives. Fifty-six of 67 patients completed the intervention. Both groups achieved targeted intakes of n-3 and n-6 fatty acids. In intention-to-treat analysis, the H3-L6 intervention produced significantly greater improvement in the HIT-6 score (-7.5 vs -2.1; P<0.001) and the number of Headache Days per month (-8.8 vs -4.0; P=0.02), compared to the L6 group. The H3-L6 intervention also produced significantly greater reductions in Headache Hours per day (-4.6 vs -1.2; P=0.01) and the n-6 in HUFA score (-21.0 vs -4.0%; P<0.001), and greater increases in antinociceptive n-3 pathway markers 18-hydroxy-eicosapentaenoic acid (+118.4 vs +61.1%; P<0.001) and 17-hydroxy-docosahexaenoic acid (+170.2 vs +27.2; P<0.001). A dietary intervention increasing n-3 and reducing n-6 fatty acids reduced headache pain, altered antinociceptive lipid mediators, and improved quality-of-life in this population.
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Affiliation(s)
- Christopher E Ramsden
- Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA Department of Physical Medicine and Rehabilitation, Program on Integrative Medicine, University of North Carolina-Chapel Hill, NC, USA Department of Biostatistics, School of Public Health, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA Nutrition Research and Metabolism Core, North Carolina Translational Clinical Sciences Institute, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA Department of Pediatric Gastroenterology, Hepatology and Nutrition, University of California, San Diego, San Diego, CA, USA School of Medicine and Pharmacology, Royal Perth Hospital, The University of Western Australia, Perth, Australia Division of Gastroenterology and Hepatology, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA School of Dentistry, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA Department of Neurology, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA
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Suwaki N, Mann DJ. Potential role of cyclin D1in DNA damage response. Breast Cancer Res 2006. [PMCID: PMC3300260 DOI: 10.1186/bcr1568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Kinnaird JH, Bumstead JM, Mann DJ, Ryan R, Shirley MW, Shiels BR, Tomley FM. EtCRK2, a cyclin-dependent kinase gene expressed during the sexual and asexual phases of the Eimeria tenella life cycle. Int J Parasitol 2004; 34:683-92. [PMID: 15111090 DOI: 10.1016/j.ijpara.2004.01.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2003] [Revised: 01/05/2004] [Accepted: 01/07/2004] [Indexed: 11/24/2022]
Abstract
EtCRK2, a cyclin-dependent kinase from the coccidian parasite, Eimeria tenella is closely related to eukaryotic cyclin-dependent kinases that regulate progression of the cell cycle and to several cyclin-dependent kinases identified in the Apicomplexa. Northern blot analyses revealed that EtCRK2 is transcribed during both asexual (first-generation schizogony) and sexual (oocyst sporulation) replicative phases of the parasite life cycle. In addition, it appears to be transcriptionally regulated during meiosis. Recombinant EtCRK2 produced in Escherichia coli has kinase activity which is significantly stimulated by the addition of vertebrate cyclin A. This cyclin-dependent kinase may play a significant role in regulating critical cell cycle events during both asexual proliferation and sexual development of the parasite.
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Affiliation(s)
- J H Kinnaird
- Veterinary Parasitology, Institute of Comparative Medicine, University of Glasgow, Garscube Estate, Bearsden Road, Glasgow G61 1QH, UK.
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Sandeman SR, Lloyd AW, Tighe BJ, Franklin V, Li J, Lydon F, Liu CSC, Mann DJ, James SE, Martin R. A model for the preliminary biological screening of potential keratoprosthetic biomaterials. Biomaterials 2003; 24:4729-39. [PMID: 14530070 DOI: 10.1016/s0142-9612(03)00370-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A series of in vitro screening assays for the preliminary selection of biomaterials for use in the fabrication of artificial corneas (keratoprostheses) (KPros) have been investigated. These screening assays assessed the initial binding of inflammatory and cell adhesive proteins, activation of inflammatory proteins, adhesion of keratocytes, epithelial cells and macrophages and the production of inflammatory cytokines by keratocytes contacting biomaterials. Central optic biomaterials were selected on the basis of low-inflammatory and cell adhesion potential. Peripheral skirt materials were selected on the basis of low-inflammatory potential but good cell adhesion to anchor the implant within the host cornea. Green fluorescent protein (GFP) gene transfer was used in a novel context to investigate cell invasion in the absence of external staining techniques. Confocal laser scanning microscopy and scanning electron microscopy were used to investigate GFP positive keratocyte invasion of porous materials. The results of in vitro assays were compared to a corneal organ culture system in which the biomaterials were assessed within a stromal environment. A range of polyurethane-based interpenetrating polymers with a range of water contents were screened. All materials showed low-inflammatory potential. A reduction in biomaterial water content induced an increase in complement C3 and fibronectin binding and in cell adhesion to materials, whilst differences in co-monomer formulation had little impact. The screening methods used in the current study provide a suitable preliminary assessment regime for the in vitro evaluation of potential KPro materials.
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Affiliation(s)
- S R Sandeman
- Biomedical Materials Research Group, School of Pharmacy and Biomolecular Sciences, University of Brighton, Moulsecoomb Brighton BN2 4GJ, UK
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Child ES, Mann DJ. Novel properties of the cyclin encoded by Human Herpesvirus 8 that facilitate exit from quiescence. Oncogene 2001; 20:3311-22. [PMID: 11423981 DOI: 10.1038/sj.onc.1204447] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2001] [Revised: 03/01/2001] [Accepted: 03/07/2001] [Indexed: 11/08/2022]
Abstract
Viral DNA replication is generally dependent upon circumventing host cell cycle control to force S phase entry in an otherwise quiescent cell. Here we describe novel attributes of the cyclin encoded by Human Herpesvirus 8 (K cyclin) that enable it to subvert the quiescent state. K cyclin is most similar to the mammalian D-type cyclins in primary sequence but displays properties more akin to those of cyclin E. K cyclin (like cyclin E) can autonomously couple with its cognate cdk subunit and localize to the nucleus. D-type cyclins require mitogen stimulated accessory factors (such as p21(Cip1) and p27(Kip1)) to facilitate both of these processes. A striking difference between K cyclin and mammalian cyclins is that K cyclin binding to cdk6 can substantially activate the catalytic activity of the complex without the requirement for cyclin H/cdk7 phosphorylation of the cdk T-loop; this phosphorylation is obligatory for endogenous cyclin/cdk activity. However, K cyclin/cdk6 complexes are not totally immune from cell cycle control since CAK phosphorylation is necessary for complete activation. Thus, CAK phosphorylated K cyclin/cdk6 targets multiple sites in the retinoblastoma protein (pRb) whereas the unphosphorylated complex targets a single site. The restricted substrate specificity of the non-CAK phosphorylated K cyclin/cdk6 complex is insufficient to enable K cyclin-mediated S phase entry. Thus, the viral K cyclin is reliant upon endogenous CAK activity to subvert the quiescent state.
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Affiliation(s)
- E S Child
- Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, SW7 2AY, UK
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Abstract
D-type cyclin homologs have been found in the genomes of herpesviruses associated with neoplasias. They appear to exploit features of G(1) cyclins but extend their properties to allow for deregulation of the cell cycle. Advances in the study of the molecular basis for these novel features as well as the potential role of viral cyclins in tumorigenesis are addressed.
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Affiliation(s)
- H Laman
- Molecular Oncology Laboratory, Imperial Cancer Research Fund, London, WC2A 3PX, UK
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Abstract
DNA tumour viruses have evolved a number of mechanisms by which they deregulate normal cellular growth control. We have recently described the properties of a cyclin encoded by human herpesvirus 8 (also known as Kaposi's sarcoma-associated herpesvirus) which is able to resist the actions of p16(Ink4a), p21(Cip1) and p27(Kip1) cdk inhibitors. Here we investigate the mechanism involved in the subversion of a G1 blockade imposed by overexpression of p27(Kip1). We demonstrate that binding of K cyclin to cdk6 expands the substrate repertoire of this cdk to include a number of substrates phosphorylated by cyclin-cdk2 complexes but not cyclin D1-cdk6. Included amongst these substrates is p27(Kip1) which is phosphorylated on Thr187. Expression of K cyclin in mammalian cells leads to p27(Kip1) downregulation, this being consistent with previous studies indicating that phosphorylation of p27(Kip1) on Thr187 triggers its downregulation. K cyclin expression is not able to prevent a G1 arrest imposed by p27(Kip1) in which Thr187 is mutated to non-phosphorylatable Ala. These results imply that K cyclin is able to bypass a p27(Kip1)-imposed G1 arrest by facilitating phosphorylation and downregulation of p27(Kip1) to enable activation of endogenous cyclin-cdk2 complexes. The extension of the substrate repertoire of cdk6 by K cyclin is likely to contribute to the deregulation of cellular growth by this herpesvirus-encoded cyclin.
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Affiliation(s)
- D J Mann
- Department of Biology and Biochemistry, Brunel University, Uxbridge, Middlesex, UB8 3PX.
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Armstrong CG, Dombradi V, Mann DJ, Cohen PT. Cloning of a novel testis specific protein serine/threonine phosphatase, PPN 58A, from Drosophila melanogaster. Biochim Biophys Acta 1998; 1399:234-8. [PMID: 9765603 DOI: 10.1016/s0167-4781(98)00117-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
A gene encoding a novel member of the PPP family of protein serine/threonine phosphatases, termed PPN 58A, was cloned from Drosophila melanogaster. The deduced amino acid sequence of PPN 58A exhibits 59-62% identity to D. melanogaster PP1 isoforms, 51% identity to D. melanogaster PPY 55A and < or = 40% identity to other members of the PPP family. The single copy gene PPN 58A maps to chromosome 2 locus 58A. Analysis of PPN 58A mRNA reveals that, like PPY 55A, PPN 58A is a testis specific enzyme.
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Affiliation(s)
- C G Armstrong
- Department of Biochemistry, University of Dundee, UK
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Abstract
The passage of mammalian cells through the restriction point into the S phase of the cell cycle is regulated by the activities of Cdk4 and Cdk6 complexed with the D-type cyclins and by cyclin E/Cdk2. The activities of these holoenzymes are constrained by CDK inhibitory proteins. The importance of the restriction point is illustrated by its deregulation in many tumour cells and upon infection with DNA tumour viruses. Here we describe the properties of cyclins encoded by two herpesviruses, herpesvirus saimiri (HVS) which can transform blood lymphocytes and induce malignancies of lymphoid origin in New World primates, and human herpesvirus 8 (HHV8) implicated as a causative agent of Kaposi's sarcoma and body cavity lymphomas. Both viral cyclins form active kinase complexes with Cdk6 that are resistant to inhibition by the CDK inhibitors p16(Ink4a), p21Cip1 and p27Kip1. Furthermore, ectopic expression of a viral cyclin prevents G1 arrest imposed by each inhibitor and stimulates cell-cycle progression in quiescent fibroblasts. These results suggest a new mechanism for deregulation of the cell cycle and indicate that the viral cyclins may contribute to the oncogenic nature of these viruses.
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Affiliation(s)
- C Swanton
- Imperial Cancer Research Fund, London, UK
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Mann DJ, Higgins T, Jones NC, Rozengurt E. Differential control of cyclins D1 and D3 and the cdk inhibitor p27Kip1 by diverse signalling pathways in Swiss 3T3 cells. Oncogene 1997; 14:1759-66. [PMID: 9150381 DOI: 10.1038/sj.onc.1201134] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Quiescent Swiss 3T3 cells can be induced to re-enter the cell cycle by stimulation of a variety of growth factor-dependent signal transduction cascades. We have utilised this cell system to investigate the point of convergence of mitogenic signalling by analysing the changes that distinct mitogens induce in the components of the cell cycle regulatory machinery (the G1 cyclins, cdks and their inhibitors). In the presence of insulin, activation of cAMP-dependent protein kinase caused a dramatic post-transcriptional down-regulation of p27(Kip1), an increase in cyclin D3 but had little effect on cyclin D1 levels, whilst activation of protein kinase C had a more modest effect on cyclin D3 and p27(Kip1) but caused a striking elevation in the expression of cyclin D1. The neuropeptide bombesin, when combined with insulin, caused increased expression of cyclin D1 and down-regulation of p27(Kip1) mRNA and protein. Thus each combination of mitogenic agents had different effects on the components responsible for regulating the orderly progression of the cell cycle. This outcome is incompatible with a single route to mitogenesis and demonstrates that different mitogens remain distinct in the signalling responses they initiate, only converging at the levels of the expression of the D-type cyclins and the inhibitor p27(Kip1).
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Affiliation(s)
- D J Mann
- Gene Regulation Laboratory, Imperial Cancer Research Fund, London
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Abstract
BACKGROUND The transition from G1 to S phase is the key regulatory step in the mammalian cell cycle. This transition is regulated positively by G1-specific cyclin-dependent kinases (cdks) and negatively by the product of the retinoblastoma tumour suppressor gene, pRb. Hypophosphorylated pRb binds to and inactivates the E2F transcription factor, which controls the expression of genes required for S-phase progression. Hyperphosphorylation of pRb in late G1 phase results in the accumulation of active E2F, a critical event in the progression to S phase. The E2F factor is not a single entity, but rather represents a family of highly related molecules, all of which bind to pRb or the pRb-related proteins p107 and p130. RESULTS In this study, we have used specific inhibitors of cdks to explore the requirements for cell-cycle progression from G1 to S phase. Expression of p16Ink4, which specifically inhibits cyclin D-directed cdks, blocks cells in G1 phase; this block can be overcome by expression of the viral proteins that inactivate pRb or by E2F-1. Importantly however, the G1 arrest is not overcome by overexpression of E2F-4. By using chimeric E2F proteins, containing amino-acid sequences from E2F-1 and E2F-4, we have shown that their differential abilities to overcome a p16-imposed arrest is determined by their respective amino-terminal regions. We also demonstrate that E2F-1 can promote entry into S phase without concomitant phosphorylation of pRb. In contrast to the p16-mediated G1 block, G1 arrest mediated by the cdk inhibitors p21Cip1 or p27Kip1 cannot be bypassed either by inactivation of pRb or overexpression of E2F family members. CONCLUSIONS These data demonstrate that the role of the cyclin D-directed cdks in promoting the progression of cells from G1 into S phase is wholly to activate an E2F-1-like activity through phosphorylation, thus preventing the formation of the E2F-pRb complex. The cyclin E-cdk2 complex is also required for the G1/S transition but has a different and as yet undefined role. We also provide evidence for a functional difference between E2F-1 and E2F-4, dependant upon the region that contains the DNA-binding and dimerization domains. These results indicate that these two E2F family members are likely to regulate the expression of different subsets of E2F-responsive promoters.
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Affiliation(s)
- D J Mann
- Gene Regulation Laboratory, Imperial Cancer Research Fund, London, UK
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Hidalgo MA, Mann DJ, Fuller BJ, Green CJ. Effects of depolarizing or non-depolarizing preservation solutions on human endothelial cells during cold hypoxia. Clin Sci (Lond) 1996; 90:135-41. [PMID: 8829883 DOI: 10.1042/cs0900135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
1. Hypothermic storage of whole organs flushed with a preservation solution is common practice in clinical transplantation. This procedure leaves vascular endothelial cells in direct contact with the preservation solution during the length of the cold ischaemic period. 2. Aiming to study the effects of organ preservation on vascular endothelium, we subjected cultures of human umbilical vein endothelial cells to hypoxic and hypothermic storage conditions in vitro for 3 or 16 h. Four preservation solutions with different levels of sodium and potassium were tested. Morphometric analysis and 51Cr leakage index were used to assess monolayer continuity, cell viability and membrane integrity. 3. Hypothermic storage resulted in severe changes in endothelial cell morphology with formation of intercellular gaps that destroyed monolayer continuity after only 3h. Cellular blebbing was a common feature in seriously damaged cells. 4. Morphometric analysis and 51Cr leakage results correlated well. No significant differences between the solutions tested were found after 3h of hypothermic hypoxic storage. After 16h, viability and monolayer continuity were significantly better preserved (Mann-Whitney, P < 0.01) in cells stored in lactobionate-based solutions than in hypertonic citrate solutions. No significant differences were found between endothelial cells stored in extracellular versus intracellular types of solutions for the lactobionate-based solutions. 5. The results of the present experiment showed that after a period of hypothermic hypoxic storage, vascular endothelial cells appeared morphologically deformed and poorly attached in vitro. Lactobionate-based preservation solutions were more effective in preserving viability and continuity. Protection of vascular endothelium under cold hypoxic conditions could be a critical factor in successfully preserving organs for transplantation.
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Affiliation(s)
- M A Hidalgo
- Department of Surgical Research, Northwick Park Institute for Medical Research, Harrow, Middlesex, U.K
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Armstrong CG, Mann DJ, Berndt N, Cohen PT. Drosophila PPY, a novel male specific protein serine/threonine phosphatase localised in somatic cells of the testis. J Cell Sci 1995; 108 ( Pt 11):3367-75. [PMID: 8586649 DOI: 10.1242/jcs.108.11.3367] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Drosophila protein phosphatase Y (PPY) displays 64% amino acid identity to protein serine/threonine phosphatase 1 (PP1) and 39% to protein phosphatase 2A (PP2A). Here we show by expression of cDNA in bacteria, that PPY is a protein serine phosphatase and that its biochemical properties are distinct from PP1 in both substrate specificity and regulation by the thermostable inhibitory proteins inhibitor 1 and inhibitor 2. We also demonstrate that PPY is a novel testis specific protein phosphatase by analysis of both mRNA and protein distribution. More precise immunolocalisation within the testis, using affinity purified anti-PPY protein and anti-PPY peptide antibodies, shows that PPY is present in somatic cyst cells, which encase the germ cells. The predominant location of PPY is in the nuclei of both head and tail cyst cells throughout the length of the testis except for the apical tip. The distribution of PPY, coupled with its unique biochemical properties, suggests that PPY may be required to prevent cyst cell division, increase transcription for provision of nutrients to the germ cells and/or provide a signal for spermatocyte differentiation.
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Affiliation(s)
- C G Armstrong
- Department of Biochemistry, University, Dundee, Scotland, UK
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Lukas J, Parry D, Aagaard L, Mann DJ, Bartkova J, Strauss M, Peters G, Bartek J. Retinoblastoma-protein-dependent cell-cycle inhibition by the tumour suppressor p16. Nature 1995; 375:503-6. [PMID: 7777060 DOI: 10.1038/375503a0] [Citation(s) in RCA: 701] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
D-type cyclins, in association with the cyclin-dependent kinases Cdk4 or Cdk6, promote progression through the G1 phase of the cell cycle by phosphorylating the retinoblastoma protein (RB). The activities of Cdk4 and Cdk6 are constrained by inhibitors such as p16, the product of the CDKN2 gene on human chromosome 9p21 (refs 12-14). The frequent deletion or mutation of CDKN2 in tumour cells suggests that p16 acts as a tumour suppressor. We show that wild-type p16 arrests normal diploid cells in late G1, whereas a tumour-associated mutant of p16 does not. Significantly, the ability of p16 to induce cell-cycle arrest is lost in cells lacking functional RB, including primary fibroblasts from Rb-/- mouse embryos. Thus, loss of p16, overexpression of D-cyclins and loss of RB have similar effects on G1 progression, and may represent a common pathway to tumorigenesis.
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Affiliation(s)
- J Lukas
- Danish Cancer Society, Division of Cancer Biology, Copenhagen
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Parry D, Bates S, Mann DJ, Peters G. Lack of cyclin D-Cdk complexes in Rb-negative cells correlates with high levels of p16INK4/MTS1 tumour suppressor gene product. EMBO J 1995; 14:503-11. [PMID: 7859739 PMCID: PMC398108 DOI: 10.1002/j.1460-2075.1995.tb07026.x] [Citation(s) in RCA: 233] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
D-type cyclins, in association with the cyclin-dependent kinases Cdk4 or Cdk6, regulate events in the G1 phase of the cell cycle and may contribute to the phosphorylation of the retinoblastoma gene product (Rb). However, in cells in which the function of Rb has been compromised, either by naturally arising mutations or through binding to proteins encoded by DNA tumour viruses, Cdk4 and Cdk6 are not associated with D cyclins. Instead, both kinases form binary complexes with a stable 16 kDa protein (p16) encoded by the putative tumour suppressor gene INK4/MTS1 on human chromosome 9p21. Here we show an inverse correlation between Rb status and the expression of p16. Since Rb-negative cells express high levels of p16, we suggest that in these cells p16 competes with D cyclins for binding to Cdk4 and Cdk6 and prevents formation of active complexes. In line with these predictions, DNA tumour virus oncoproteins do not disrupt cyclin D1-Cdk4 complexes in cells lacking p16.
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Affiliation(s)
- D Parry
- Molecular Oncology Laboratory, Imperial Cancer Research Fund, London, UK
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Abstract
Six patients with chronic myofascial pain syndrome involving cervical paraspinal and shoulder girdle muscles received trigger point injections of botulinum toxin type A (Botox) or saline in a randomized, double-blind, placebo-controlled study. Four patients experienced reduction in pain of at least 30% following Botox, but not saline, injections, as measured by visual analog scales, verbal descriptors for pain intensity and unpleasantness, palpable muscle firmness, and pressure pain thresholds. Results were statistically significant. Botox, which inhibits muscle contraction by blocking the release of acetylcholine from peripheral nerves, appears to be an effective treatment for focal myofascial pain disorders.
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Affiliation(s)
- William P Cheshire
- Department of Neurology, University of North Carolina, 751 Clinical Sciences Building, Chapel Hill, NC 27599 USA
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Mann DJ, Dombrádi V, Cohen PT. Drosophila protein phosphatase V functionally complements a SIT4 mutant in Saccharomyces cerevisiae and its amino-terminal region can confer this complementation to a heterologous phosphatase catalytic domain. EMBO J 1993; 12:4833-42. [PMID: 8223492 PMCID: PMC413936 DOI: 10.1002/j.1460-2075.1993.tb06173.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The sequence of a Drosophila melanogaster cDNA encoding a novel 35 kDa protein serine/threonine phosphatase, termed PPV, is presented. PPV is 40-41% identical to Drosophila PP1, 53% identical to Drosophila PP2A and 63% identical to Saccharomyces cerevisiae SIT4. Complementation studies demonstrated that PPV can functionally rescue a temperature sensitive mutant of SIT4, a protein phosphatase required for the G1 to S transition of the cell cycle. When placed under the SIT4 promoter, PPV cDNA is able to replace the SIT4 gene in S. cerevisiae. The amino-terminal domain of PPV fused to another phosphatase catalytic region (PP1) also rescues the temperature sensitive SIT4 mutant and the SIT4 deletion mutant, implicating this region in binding to regulatory subunits and/or altering specificity. In Drosophila, a substantial transient increase in both PPV mRNA and protein occurs in late syncytial and early cellular blastoderm embryos. At the latter stage PPV is localized to the cytoplasm of cells at the cortex. This increase in PPV correlates with introduction of the G2 phase of the cell cycle, elevated zygotic transcription and cellularization, indicating that PPV may play a role in one or more of these processes.
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Affiliation(s)
- D J Mann
- Department of Biochemistry, The University, Dundee, UK
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Dombrádi V, Mann DJ, Saunders RD, Cohen PT. Cloning of the fourth functional gene for protein phosphatase 1 in Drosophila melanogaster from its chromosomal location. Eur J Biochem 1993; 212:177-83. [PMID: 8383037 DOI: 10.1111/j.1432-1033.1993.tb17648.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Complementary DNA encoding a catalytic subunit of protein phosphatase 1, PP1 87B, hybridises at four positions (87B, 9C, 13C and 96A) to Drosophila melanogaster polytene chromosomes, three of which are known to be expressed [Dombrádi, V., Axton, J.M., Brewis, N.D., Da Cruz e Silva, E.F., Alphey, L. & Cohen, P.T.W. (1990) Eur. J. Biochem. 194, 739-745]. The fourth gene has been isolated by screening a genomic library of cosmid clones, representing division 13 of the X-chromosome of D. melanogaster, with a PP1 87B probe. This library was constructed as part of the Drosophila genome mapping project [Sidén-Kiamos, I., Saunders, R.D.C., Spanos, L., Majerus, T., Trenear, J., Savakis, C., Louis, C., Glover, D.M., Ashburner, M. & Kafatos, F.C. (1990) Nucleic Acids Res. 18, 6261-6270]. The 5' non-coding region of the isolated gene hybridised to cytological position 13C1-2. By combining reverse transcription and the polymerase chain reaction, the gene was shown to be expressed at a very low level. The PP1 13C gene encodes a protein of 302 amino acids with a predicted molecular mass of 34.5 kDa. It shows 85-94% amino acid identity to the other three protein phosphatase 1 catalytic subunits (PP1 87B, PP1 96A and PP1 9C) described previously, being most closely related to the isoform PP1 87B, which is involved in the control of chromosome separation at cell division and the regulation of chromosome condensation at interphase.
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Affiliation(s)
- V Dombrádi
- Department of Biochemistry, The University, Dundee, Scotland
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Abstract
The levels of malic-enzyme mRNA and activity were determined in primary cultures of adult rat hepatocytes maintained on either rat-tail collagen or a laminin-rich substratum. Cells plated on laminin-rich gels exhibited substantially improved patterns of albumin and malic-enzyme expression when compared with cells maintained on rat-tail collagen. Moreover, hepatocytes plated on the laminin-rich matrix displayed marked malic-enzyme inducibility in response to tri-iodothyronine and dichloroacetate, especially in the presence of insulin. However, Northern blot analysis revealed that the ratio of the amounts of the two major malic-enzyme mRNA species (2.0 and 3.1 kb) was reversed when compared with that found in the liver in vivo, the altered levels of these two species being closer to those found in non-hepatic tissues. These findings indicate that, although the hormonal responsiveness of isolated hepatocytes maintained on laminin-rich gels is markedly improved, and approaches the degree of induction demonstrated in the liver in vivo, the mechanisms of control differ, indicating a loss of liver-specific expression.
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Affiliation(s)
- D J Mann
- Department of Molecular Biology and Biotechnology, University of Sheffield, U.K
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Mann DJ, Campbell DG, McGowan CH, Cohen PT. Mammalian protein serine/threonine phosphatase 2C: cDNA cloning and comparative analysis of amino acid sequences. Biochim Biophys Acta 1992; 1130:100-4. [PMID: 1311954 DOI: 10.1016/0167-4781(92)90471-b] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Complementary DNA encoding rat protein phosphatase 2C alpha was obtained from a liver library and used to isolate the homologous cDNAs from rabbit liver and human teratocarcinoma libraries. The amino acid sequences of the three enzymes deduced from the cDNA (382 amino acids) were extremely similar (greater than 99% identity), the maximum number of differences (between rat and human) being four. Amino acid sequences of peptides corresponding to 238 residues (61%) of the protein phosphatase 2C beta isoform from rabbit skeletal muscle were determined and showed 12 differences from the recently published sequence of the rat liver enzyme deduced from the cDNA (95% identity).
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Affiliation(s)
- D J Mann
- Department of Biochemistry, The University, Dundee, UK
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Abstract
The expression of hepatic cytosolic malic enzyme in the developing rat has been studied by molecular-biological techniques. Malic enzyme mRNA was barely detectable throughout the neonatal period, but increased to significant levels immediately before weaning. Northern-blot analysis demonstrated that the two major malic enzyme mRNA species displayed non-co-ordinate control during development, with the 2.0 kb form accumulating to a greater extent than the 3.1 kb form. A novel 1.6 kb mRNA species was found to predominate in foetal samples. Tri-iodothyronine treatment of neonatal rats caused premature induction of all three malic enzyme mRNA species. Dietary studies also showed precocious induction of the mRNA with diets high in carbohydrate, but not with those high in fat.
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Affiliation(s)
- D J Mann
- Department of Molecular Biology and Biotechnology, University of Sheffield, U.K
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Abstract
A major factor relating to the oversight of neurological dysfunction and seizures caused by magnesium (Mg++) depletion, involves the buffer functions of the skeletal system orchestrated primarily by the parathyroid. A Mg++ depleted subject may appear relatively asymptomatic until a short period after homeostatic responses go into effect. The results can be devastating if not recognized promptly and treated appropriately. This series of events can best be demonstrated in veterinary medicine but we propose that analogous syndromes occur in clinical medicine. Evidence is presented to support the hypothesis that in subjects with parathyroid hyperactivity and Mg++ deficiency, the stimulus of a rise in serum ionic calcium (Ca++), and the resultant inhibition of parathyroid hormone (PTH) secretion, trigger the transfer of Ca++, Mg++ and other ions from the extracellular space into the exchangeable bone compartment. More importantly, there is a transfer of Mg++ ions from the cerebrospinal fluid into the blood and ultimately into the bone compartment. If the gradient is large and the stimulus adequate, neurological signs and symptoms may be induced. The degree of Ca++ and Mg++ depletion of the peripheral bone and the amount and duration of Ca++ ion increase largely determine the duration and severity of symptoms. The symptom complex is facilitated by sympathetic stimulation. An analogous situation may exist with sodium (Na+).
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Abstract
Five protein serine/threonine phosphatases (PP) have been identified by cloning cDNA from mammalian and Drosophila libraries. These novel enzymes, which have not yet been detected by the techniques of protein chemistry and enzymology, are termed PPV, PP2Bw, PPX, PPY and PPZ. The complete amino acid sequences of PPX, PPY and PPZ and an almost complete sequence of PPV are presented. In the catalytic domain PPV and PPX are more similar to PP2A (57-69% identity) than PP1 (45-49% identity), while PPY and PPZ are more similar to PP1 (66-68% identity) than PP2A (44% identity). The cDNA for PP2Bw encodes a novel Ca2+/calmodulin-dependent protein phosphatase only 62% identical to PP2B in the catalytic domain. Approaches for determining the cellular functions of these protein phosphatases are discussed.
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Affiliation(s)
- P T Cohen
- Department of Biochemistry, The University, Dundee, Scotland, UK
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Brown DQ, Shaw LM, Pittock JW, Mann DJ, Hardiman J, Pogach R, Gold J. Modification of WR-2721 toxicity and radioprotection by an inhibitor of alkaline phosphatase. Int J Radiat Oncol Biol Phys 1986; 12:1491-3. [PMID: 3019966 DOI: 10.1016/0360-3016(86)90201-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We used levamisole, an inhibitor of alkaline phosphatase, to study the role of that enzyme in mediating the metabolic activation, toxicity, and radioprotection of WR-2721 in intact mice. We found the toxicity of WR-2721 was slightly decreased by prior subcutaneous (SQ) injection of 40 mg/kg of levamisole. In studying the effect of levamisole on WR-2721 radioprotection, we found that intraperitoneal (i.p.) injection of levamisole had little or no effect on radioprotection of the gastrointestinal and the hematopoietic systems. Even this small reduction of protection was due in part to the toxicity of levamisole as demonstrated when levamisole was injected following, rather than before, WR-2721-radiation treatment. To determine whether levamisole inhibited the activation (i.e., dephosphorylation) of WR-2721 to WR-1065, we assayed WR-1065 in the jejunum using an HPLC electrochemical assay. SQ injection of 75 mg/kg levamisole 10 min prior to WR-2721 reduced the WR-1065 observed 10 min after WR-2721 administration by 37%. In conclusion, levamisole appears to be too toxic and non-specific to be useful in studying and regulating the metabolism, toxicity and radioprotection of WR-2721.
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Namba M, Ghatei MA, Bishop AE, Gibson SJ, Mann DJ, Polak JM, Bloom SR. Presence of neuromedin B-like immunoreactivity in the brain and gut of rat and guinea-pig. Peptides 1985; 6 Suppl 3:257-63. [PMID: 3913907 DOI: 10.1016/0196-9781(85)90383-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A recently developed specific radioimmunoassay for neuromedin B, originally isolated from porcine spinal cord, was used to investigate its distribution in rat and guinea-pig brain and gut. In both species, neuromedin B-like immunoreactivity was present in several regions of brain, and high concentrations occurred in the pituitary. The immunoreactivity was widely distributed throughout the entire length of gastrointestinal tract and pancreas, and relatively high concentrations were found in the oesophagus and rectum. Immunocytochemistry localised neuromedin B-like immunoreactivity to nerve fibers in the rat brain and gut. Immunoreactive fibres were visualized in the medial thalamus and were found very frequently in the circular muscle of the gut. Gel permeation chromatography of pituitary and intestinal extracts from both species revealed presence of two peaks of neuromedin B-like immunoreactivity, the later of which co-eluted with the synthetic porcine neuromedin B standard. Reverse phase high pressure liquid chromatography showed that material corresponding to the later peak was eluted in the exact position of synthetic porcine neuromedin B, whereas the larger molecular size material from the earlier peak was more hydrophobic in nature.
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