201
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Abstract
The immunological synapse controls T-lymphocyte function by polarizing effector responses towards the antigen-presenting cell. In this review, I discuss the molecular pathways required for synapse assembly, focusing on the central roles played by lipid second-messenger signalling.
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202
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Compressive stress inhibits proliferation in tumor spheroids through a volume limitation. Biophys J 2015; 107:1821-1828. [PMID: 25418163 DOI: 10.1016/j.bpj.2014.08.031] [Citation(s) in RCA: 149] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 08/04/2014] [Accepted: 08/18/2014] [Indexed: 11/23/2022] Open
Abstract
In most instances, the growth of solid tumors occurs in constrained environments and requires a competition for space. A mechanical crosstalk can arise from this competition. In this article, we dissect the biomechanical sequence caused by a controlled compressive stress on multicellular spheroids (MCSs) used as a tumor model system. On timescales of minutes, we show that a compressive stress causes a reduction of the MCS volume, linked to a reduction of the cell volume in the core of the MCS. On timescales of hours, we observe a reversible induction of the proliferation inhibitor, p27Kip1, from the center to the periphery of the spheroid. On timescales of days, we observe that cells are blocked in the cell cycle at the late G1 checkpoint, the restriction point. We show that the effect of pressure on the proliferation can be antagonized by silencing p27Kip1. Finally, we quantify a clear correlation between the pressure-induced volume change and the growth rate of the spheroid. The compression-induced proliferation arrest that we studied is conserved for five cell lines, and is completely reversible. It demonstrates a generic crosstalk between mechanical stresses and the key players of cell cycle regulation. Our results suggest a role of volume change in the sensitivity to pressure, and that p27Kip1 is strongly influenced by this change.
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203
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Gibbs PEM, Miralem T, Maines MD. Biliverdin reductase: a target for cancer therapy? Front Pharmacol 2015; 6:119. [PMID: 26089799 PMCID: PMC4452799 DOI: 10.3389/fphar.2015.00119] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 05/20/2015] [Indexed: 12/30/2022] Open
Abstract
Biliverdin reductase (BVR) is a multifunctional protein that is the primary source of the potent antioxidant, bilirubin. BVR regulates activities/functions in the insulin/IGF-1/IRK/PI3K/MAPK pathways. Activation of certain kinases in these pathways is/are hallmark(s) of cancerous cells. The protein is a scaffold/bridge and intracellular transporter of kinases that regulate growth and proliferation of cells, including PKCs, ERK and Akt, and their targets including NF-κB, Elk1, HO-1, and iNOS. The scaffold and transport functions enable activated BVR to relocate from the cytosol to the nucleus or to the plasma membrane, depending on the activating stimulus. This enables the reductase to function in diverse signaling pathways. And, its expression at the transcript and protein levels are increased in human tumors and the infiltrating T-cells, monocytes and circulating lymphocytes, as well as the circulating and infiltrating macrophages. These functions suggest that the cytoprotective role of BVR may be permissive for cancer/tumor growth. In this review, we summarize the recent developments that define the pro-growth activities of BVR, particularly with respect to its input into the MAPK signaling pathway and present evidence that BVR-based peptides inhibit activation of protein kinases, including MEK, PKCδ, and ERK as well as downstream targets including Elk1 and iNOS, and thus offers a credible novel approach to reduce cancer cell proliferation.
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Affiliation(s)
- Peter E M Gibbs
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry , Rochester, NY, USA
| | - Tihomir Miralem
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry , Rochester, NY, USA
| | - Mahin D Maines
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry , Rochester, NY, USA
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204
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Boudreault PL, Mattler JK, Wender PA. Studies on the regio- and diastereo-selective epoxidation of daphnanes and tiglianes. Tetrahedron Lett 2015; 56:3423-3427. [PMID: 26034334 PMCID: PMC4449265 DOI: 10.1016/j.tetlet.2015.01.126] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Daphnanes and tiglianes are diterpenes with a shared tricyclic 5-7-6 ring system. Many members exhibit significant biological activities often associated with protein kinase C signaling. Many of these natural products (~100) have a C6-C7 α-epoxide whose influence on biological activity is little studied. Using the more readily available phorbol ester PDBu as a test substrate, we report an efficient, and potentially general, α-epoxidation method based on a vanadium-catalyzed asymmetric epoxidation with bishydroxamic acid (BHA) ligands.
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Affiliation(s)
- Pierre-Luc Boudreault
- Department of Chemistry, Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305-5080, USA
| | - Jennifer K. Mattler
- Department of Chemistry, Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305-5080, USA
| | - Paul A. Wender
- Department of Chemistry, Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305-5080, USA
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205
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Fernández-Araujo A, Alfonso A, Vieytes MR, Botana LM. Yessotoxin activates cell death pathways independent of Protein Kinase C in K-562 human leukemic cell line. Toxicol In Vitro 2015; 29:1545-54. [PMID: 26025416 DOI: 10.1016/j.tiv.2015.05.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 05/12/2015] [Accepted: 05/16/2015] [Indexed: 01/30/2023]
Abstract
Protein Kinase C (PKC) is a group of enzymes involved in pro-survival or pro-apoptotic events depending on the cellular model. Moreover, Yessotoxin (YTX) modulates its expression and activates different cell death pathways. In K-562 tumor cell line, YTX induces apoptosis and autophagy after 24 and 48 h of incubation, respectively, and the toxin carries out its action through the phosphodiesterase 4A (PDE4A). Therefore, the levels of two subtypes of PKC, conventional (cPKC) and δ isotype of novel PKC (PKCδ) were studied at these times after YTX incubation. Also their involvement in the cell death activated by the toxin and their relationship with PDE4A was checked. The expression of cPKC and PKCδ in cytosol, plasma membrane and nucleus was studied in normal and PDE4A-silenced cells. Furthermore, cell viability of normal cells, as well as cPKC-, PKCδ- and PDE4A-silenced cells was tested by Lactate Dehydrogenase (LDH) assay. As a result, PKCδ showed a key role in K-562 cell survive, since without this protein, K-562 cell decreased their viability. Furthermore, modulation of PKCs by YTX treatment was observed, however, the changes in the expression of these proteins are independent of cell death activated by the toxin. In addition, the modulation of PKCs detected is PDE4A-dependent, since the silencing of this protein change PKC expression pattern.
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Affiliation(s)
| | - Amparo Alfonso
- Dept. Farmacología, Facultad de Veterinaria, 27002 Lugo, Spain
| | | | - Luis M Botana
- Dept. Farmacología, Facultad de Veterinaria, 27002 Lugo, Spain.
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206
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Abstract
The protein kinases C (PKCs) are a family of serine/threonine kinases involved in regulating multiple essential cellular processes such as survival, proliferation, and differentiation. Of particular interest is the novel, calcium-independent PKCθ which plays a central role in immune responses. PKCθ shares structural similarities with other PKC family members, mainly consisting of an N-terminal regulatory domain and a C-terminal catalytic domain tethered by a hinge region. This isozyme, however, is unique in that it translocates to the immunological synapse between a T cell and an antigen-presenting cell (APC) upon T cell receptor-peptide MHC recognition. Thereafter, PKCθ interacts physically and functionally with downstream effectors to mediate T cell activation and differentiation, subsequently leading to inflammation. PKCθ-specific perturbations have been identified in several diseases, most notably autoimmune disorders, and hence the modulation of its activity presents an attractive therapeutic intervention. To that end, many inhibitors of PKCs and PKCθ have been developed and tested in preclinical and clinical studies. And although selectivity remains a challenge, results are promising for the future development of effective PKCθ inhibitors that would greatly advance the treatment of several T-cell mediated diseases.
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207
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Eddinger TJ. Smooth muscle-protein translocation and tissue function. Anat Rec (Hoboken) 2015; 297:1734-46. [PMID: 25125185 DOI: 10.1002/ar.22970] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Revised: 03/18/2014] [Accepted: 03/18/2014] [Indexed: 01/25/2023]
Abstract
Smooth muscle (SM) tissue is a complex organization of multiple cell types and is regulated by numerous signaling molecules (neurotransmitters, hormones, cytokines, etc.). SM contractile function can be regulated via expression and distribution of the contractile and cytoskeletal proteins, and activation of any of the second messenger pathways that regulate them. Spatial-temporal changes in the contractile, cytoskeletal or regulatory components of SM cells (SMCs) have been proposed to alter SM contractile activity. Ca(2+) sensitization/desensitization can occur as a result of changes at any of these levels, and specific pathways have been identified at all of these levels. Understanding when and how proteins can translocate within the cytoplasm, or to-and-from the plasmalemma and the cytoplasm to alter contractile activity is critical. Numerous studies have reported translocation of proteins associated with the adherens junction and G protein-coupled receptor activation pathways in isolated SMC systems. Specific examples of translocation of vinculin to and from the adherens junction and protein kinase C (PKC) and 17 kDa PKC-potentiated inhibitor of myosin light chain phosphatase (CPI-17) to and from the plasmalemma in isolated SMC systems but not in intact SM tissues are discussed. Using both isolated SMC systems and SM tissues in parallel to pursue these studies will advance our understanding of both the role and mechanism of these pathways as well as their possible significance for Ca(2+) sensitization in intact SM tissues and organ systems.
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Affiliation(s)
- Thomas J Eddinger
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
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208
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Corsini E, Galbiati V, Pinto A, Davin A, Polito L, Guaita A, Racchi M. Immunostimulatory effects of RACK1 pseudosubstrate in human leukocytes obtained from young and old donors. Oncotarget 2015; 6:6524-34. [PMID: 25779661 PMCID: PMC4466631 DOI: 10.18632/oncotarget.3002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 12/21/2014] [Indexed: 11/25/2022] Open
Abstract
Aims of this study were to investigate the ability of RACK1 pseudosubstrate alone or in combination with classical immune stimuli to activate human leukocytes, and to restore age-associated immune defects.A total of 25 donors (17 old donors, 77-79 yrs; 8 young donors, 25-34 yrs) were enrolled. To evaluate the effect of RACK1 pseudosubstrate on cytokine production and CD86 expression the whole blood assay was used. Cultures were treated with RACK1 pseudosubstrate in the presence or absence of lipopolysaccharide (LPS) or phytohaemagglutinin (PHA) and incubated for 24 h or 48 h for LPS-induced CD86 expression, TNF-α, IL-6, IL-8, IL-10 production, and PHA-induced IL-4, IL-10, IFN-γ, respectively. RACK1 pseudosubstrate alone induced IL-6, IL-8, and CD86 expression in both young and old donors, and IFN-γ in old donors. In combination with LPS an increase in IL-8, IL-10 and TNF-α was observed, also resulting in restoration of age-associated defective production, while no changes in the other parameters investigated were found.Even if based on a small sample size, these results suggest the possibility to by-pass some of age-associated immune alterations, which may be beneficial in situations were natural immune stimulation is required, and highlight a different role of PKCβ in immune cells activation.
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Affiliation(s)
- Emanuela Corsini
- Laboratory of Toxicology, DiSFeB, Università degli Studi di Milano, Milan, Italy
| | - Valentina Galbiati
- Laboratory of Toxicology, DiSFeB, Università degli Studi di Milano, Milan, Italy
| | - Antonella Pinto
- Department of Drug Sciences - Pharmacology, University of Pavia, Pavia, Italy
| | | | | | | | - Marco Racchi
- Department of Drug Sciences - Pharmacology, University of Pavia, Pavia, Italy
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209
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C6-ceramide nanoliposome suppresses tumor metastasis by eliciting PI3K and PKCζ tumor-suppressive activities and regulating integrin affinity modulation. Sci Rep 2015; 5:9275. [PMID: 25792190 PMCID: PMC4366857 DOI: 10.1038/srep09275] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 02/02/2015] [Indexed: 01/07/2023] Open
Abstract
Nanoliposomal formulation of C6-ceramide, a proapoptotic sphingolipid metabolite, presents an effective way to treat malignant tumor. Here, we provide evidence that acute treatment (30 min) of melanoma and breast cancer cells with nanoliposomal C6-ceramide (NaL-C6) may suppress cell migration without inducing cell death. By employing a novel flow migration assay, we demonstrated that NaL-C6 decreased tumor extravasation under shear conditions. Compared with ghost nanoliposome, NaL-C6 triggered phosphorylation of PI3K and PKCζ and dephosphorylation of PKCα. Concomitantly, activated PKCζ translocated into cell membrane. siRNA knockdown or pharmacological inhibition of PKCζ or PI3K rescued NaL-C6-mediated suppression of tumor migration. By inducing dephosphorylation of paxillin, PKCζ was responsible for NaL-C6-mediated stress fiber depolymerization and focal adhesion disassembly in the metastatic tumor cells. PKCζ and PI3K regulated cell shear-resistant adhesion in a way that required integrin αvβ3 affinity modulation. In conclusion, we identified a novel role of acute nanoliposomal ceramide treatment in reducing integrin affinity and inhibiting melanoma metastasis by conferring PI3K and PKCζ tumor-suppressive activities.
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210
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Abstract
![]()
In 1996,
a snapshot of the field of synthesis was provided by many
of its thought leaders in a Chemical Reviews thematic
issue on “Frontiers in Organic Synthesis”. This Accounts of Chemical Research thematic issue on “Synthesis,
Design, and Molecular Function” is intended to provide further
perspective now from well into the 21st century. Much has happened
in the past few decades. The targets, methods, strategies, reagents,
procedures, goals, funding, practices, and practitioners of synthesis
have changed, some in dramatic ways as documented in impressive contributions
to this issue. However, a constant for most synthesis studies continues
to be the goal of achieving function with synthetic economy. Whether in the form of new catalysts, reagents, therapeutic leads,
diagnostics, drug delivery systems, imaging agents, sensors, materials,
energy generation and storage systems, bioremediation strategies,
or molecules that challenge old theories or test new ones, the function
of a target has been and continues to be a major and compelling justification
for its synthesis. While the targets of synthesis have historically
been heavily represented by natural products, increasingly design,
often inspired by natural structures, is providing a new source of
target structures exhibiting new or natural functions and new or natural
synthetic challenges. Complementing isolation and screening approaches
to new target identification, design enables one to create targets de novo with an emphasis on sought-after function and synthetic
innovation with step-economy. Design provides choice. It allows one
to determine how close a synthesis will come to the ideal synthesis
and how close a structure will come to the ideal function. In
this Account, we address studies in our laboratory on function-oriented
synthesis (FOS), a strategy to achieve
function by design and with synthetic economy. By starting with function
rather than structure, FOS places an initial emphasis on target design,
thereby harnessing the power of chemists and computers to create new
structures with desired functions that could be prepared in a simple,
safe, economical, and green, if not ideal, fashion. Reported herein
are examples of FOS associated with (a) molecular recognition, leading
to the first designed phorbol-inspired protein kinase C regulatory
ligands, the first designed bryostatin analogs, the newest bryologs,
and a new family of designed kinase inhibitors, (b) target modification,
leading to highly simplified but functionally competent photonucleases—molecules
that cleave DNA upon photoactivation, (c) drug delivery, leading to
cell penetrating molecular transporters, molecules that ferry other
attached or complexed molecules across biological barriers, and (d)
new reactivity-regenerating reagents in the form of functional equivalents
of butatrienes, reagents that allow for back-to-back three-component
cycloaddition reactions, thus achieving structural complexity and
value with step-economy. While retrosynthetic analysis seeks to identify
the best way to make a target, retrofunction analysis seeks to identify
the best targets to make. In essence, form (structure) follows function.
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Affiliation(s)
- Paul A. Wender
- Departments of Chemistry
and Chemical and Systems Biology, Stanford University, Stanford, California 94305-5080, United States
| | - Ryan V. Quiroz
- Departments of Chemistry
and Chemical and Systems Biology, Stanford University, Stanford, California 94305-5080, United States
| | - Matthew C. Stevens
- Departments of Chemistry
and Chemical and Systems Biology, Stanford University, Stanford, California 94305-5080, United States
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211
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Loy BA, Lesser AB, Staveness D, Billingsley KL, Cegelski L, Wender PA. Toward a biorelevant structure of protein kinase C bound modulators: design, synthesis, and evaluation of labeled bryostatin analogues for analysis with rotational echo double resonance NMR spectroscopy. J Am Chem Soc 2015; 137:3678-85. [PMID: 25710634 DOI: 10.1021/jacs.5b00886] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Protein kinase C (PKC) modulators are currently of great importance in preclinical and clinical studies directed at cancer, immunotherapy, HIV eradication, and Alzheimer's disease. However, the bound conformation of PKC modulators in a membrane environment is not known. Rotational echo double resonance (REDOR) NMR spectroscopy could uniquely address this challenge. However, REDOR NMR requires strategically labeled, high affinity ligands to determine interlabel distances from which the conformation of the bound ligand in the PKC-ligand complex could be identified. Here we report the first computer-guided design and syntheses of three bryostatin analogues strategically labeled for REDOR NMR analysis. Extensive computer analyses of energetically accessible analogue conformations suggested preferred labeling sites for the identification of the PKC-bound conformers. Significantly, three labeled analogues were synthesized, and, as required for REDOR analysis, all proved highly potent with PKC affinities (∼1 nM) on par with bryostatin. These potent and strategically labeled bryostatin analogues are new structural leads and provide the necessary starting point for projected efforts to determine the PKC-bound conformation of such analogues in a membrane environment, as needed to design new PKC modulators and understand PKC-ligand-membrane structure and dynamics.
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Affiliation(s)
- Brian A Loy
- †Department of Chemistry and ‡Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305, United States
| | - Adam B Lesser
- †Department of Chemistry and ‡Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305, United States
| | - Daryl Staveness
- †Department of Chemistry and ‡Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305, United States
| | - Kelvin L Billingsley
- †Department of Chemistry and ‡Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305, United States
| | - Lynette Cegelski
- †Department of Chemistry and ‡Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305, United States
| | - Paul A Wender
- †Department of Chemistry and ‡Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305, United States
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212
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Abstract
In this issue of Chemistry & Biology, Antal and colleagues describe how phosphorylation optimizes the signaling range of protein kinase C (PKC) isoforms. Priming of these enzymes regulates intramolecular conformational changes, which reduces access to their diacylglycerol (DAG) binding C1 domains.
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Affiliation(s)
- Robert V Stahelin
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine-South Bend, South Bend, IN 46617, USA; Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
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213
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Abstract
The erosion and breakdown of cartilage is generally recognized to be an integral manifestation of arthritic disease, which is often accompanied by the development and progression of inflammation associated with it. Commercial shark cartilage (SC) is a popular dietary supplement taken for the prevention and/or control of chronic disease, including arthritis. The efficacy of SC in maintaining joint health remains questionable; there is a lack of sufficient reliable information on its effect on immunocompetent cells, and the potential health risks involved have not been adequately assessed. Our earlier in vitro studies showed that SC extracts induce a Th1-type inflammatory cytokine response in human leucocytes, and collagen type II alpha 1 protein was shown to be an active cytokine-inducing component in SC. In this study, we further define the cellular response to SC stimulation by classifying leucocytes into primary and secondary responders employing enriched leucocyte subpopulations. Inhibitors of specific signaling pathways were used to verify the functional effect of SC on specific pathway(s) utilized. Results indicate the monocyte/macrophage as the initially responding cell, followed by lymphocytes and the production of interferon-γ. Chemokines, MCP-1 and RANTES, were produced at significant levels in stimulated leucocyte cultures. Initial cellular activation is likely followed by activation of Jun Kinase and p38 mitogen-activated protein kinase signal transduction pathways. This study presents evidence of significant immunological reactivity of components of commercial SC supplement, which could pose a potential health risk for consumers, particularly those with underlying inflammatory disease such as irritable bowel syndrome and arthritis.
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Affiliation(s)
- Liza Merly
- Department of Biological Sciences, Florida International University , Miami, FL , USA
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214
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Pemberton JG, Stafford JL, Chang JP. Ligand-selective signal transduction by two endogenous GnRH isoforms involves biased activation of the class I PI3K catalytic subunits p110β, p110γ, and p110δ in pituitary gonadotropes and somatotropes. Endocrinology 2015; 156:218-30. [PMID: 25343277 DOI: 10.1210/en.2014-1640] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In goldfish, 2 endogenous GnRH isoforms, GnRH2 and GnRH3, are released at the pituitary and directly stimulate LH and GH release using the same population of GnRH receptors (GnRHRs) but with GnRH-specific transduction mechanisms. Previously, we have shown that phosphoinositide 3-kinases (PI3Ks) mediate GnRH2- and GnRH3-stimulated LH and GH release. Among the 3 classes of PI3Ks, class I PI3Ks are the best characterized and consist of 4 110-kDa catalytic isoforms (p110α, p110β, p110γ, and p110δ). Importantly, p110β and p110γ, but not p110α or p110δ, can be directly activated by the Gβγ heterodimer of Gαβγ protein complexes. In the present study, we examined the expression of class I PI3K isoforms and the effects of selective inhibitors of p110α, p110β, p110γ, and p110δ catalytic activity on basal, as well as acute, GnRH2- and GnRH3-stimulated LH and GH release responses using primary cultures of dispersed goldfish pituitary cells in column perifusion. Results demonstrate that p110γ and p110δ are involved in the control of basal LH and GH release, whereas p110α and p110β only regulate basal LH secretion. However, p110β and p110γ both participated in GnRH3- and GnRH2-stimulated GH release, whereas p110β and p110γ mediated GnRH2- and GnRH3-induced LH release responses, respectively. GnRH2- and GnRH3-stimulated LH release, as well as GnRH3-elicited GH release, also required p110δ. These results constitute the first evidence for the differential involvement of class I PI3K catalytic subunits in GnRH actions, in general, and suggest that GnRH2 and GnRH3 binding to GnRHRs can bias the activation of class I PI3K signaling to mediate hormone release responses in 2 distinct pituitary cell types. The involvement of both class IA and IB PI3Ks implicates Gβγ subunits, as well as other known regulators of class I PI3Ks, as important components of GnRHR-mediated responses that could influence GnRH-selective signaling in other cell types.
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Affiliation(s)
- Joshua G Pemberton
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9
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215
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Kumar V, Weng YC, Geldenhuys WJ, Wang D, Han X, Messing RO, Chou WH. Generation and characterization of ATP analog-specific protein kinase Cδ. J Biol Chem 2014; 290:1936-51. [PMID: 25505183 DOI: 10.1074/jbc.m114.598698] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To better study the role of PKCδ in normal function and disease, we developed an ATP analog-specific (AS) PKCδ that is sensitive to specific kinase inhibitors and can be used to identify PKCδ substrates. AS PKCδ showed nearly 200 times higher affinity (Km) and 150 times higher efficiency (kcat/Km) than wild type (WT) PKCδ toward N(6)-(benzyl)-ATP. AS PKCδ was uniquely inhibited by 1-(tert-butyl)-3-(1-naphthyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine (1NA-PP1) and 1-(tert-butyl)-3-(2-methylbenzyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine (2MB-PP1) but not by other 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP1) analogs tested, whereas WT PKCδ was insensitive to all PP1 analogs. To understand the mechanisms for specificity and affinity of these analogs, we created in silico WT and AS PKCδ homology models based on the crystal structure of PKCι. N(6)-(Benzyl)-ATP and ATP showed similar positioning within the purine binding pocket of AS PKCδ, whereas N(6)-(benzyl)-ATP was displaced from the pocket of WT PKCδ and was unable to interact with the glycine-rich loop that is required for phosphoryl transfer. The adenine rings of 1NA-PP1 and 2MB-PP1 matched the adenine ring of ATP when docked in AS PKCδ, and this interaction prevented the potential interaction of ATP with Lys-378, Glu-428, Leu-430, and Phe-633 residues. 1NA-PP1 failed to effectively dock within WT PKCδ. Other PP1 analogs failed to interact with either AS PKCδ or WT PKCδ. These results provide a structural basis for the ability of AS PKCδ to efficiently and specifically utilize N(6)-(benzyl)-ATP as a phosphate donor and for its selective inhibition by 1NA-PP1 and 2MB-PP1. Such homology modeling could prove useful in designing molecules to target PKCδ and other kinases to understand their function in cell signaling and to identify unique substrates.
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Affiliation(s)
- Varun Kumar
- From the Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, Ohio 44242
| | - Yi-Chinn Weng
- From the Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, Ohio 44242
| | - Werner J Geldenhuys
- the Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, Ohio 44272
| | - Dan Wang
- the Ernest Gallo Clinic and Research Center, Department of Neurology, University of California, San Francisco, Emeryville, California 94608, and
| | - Xiqian Han
- From the Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, Ohio 44242
| | - Robert O Messing
- the Ernest Gallo Clinic and Research Center, Department of Neurology, University of California, San Francisco, Emeryville, California 94608, and the Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas, Austin, Texas 78712
| | - Wen-Hai Chou
- From the Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, Ohio 44242, the Ernest Gallo Clinic and Research Center, Department of Neurology, University of California, San Francisco, Emeryville, California 94608, and
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216
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Ueda Y, Ishitsuka R, Hullin-Matsuda F, Kobayashi T. Regulation of the transbilayer movement of diacylglycerol in the plasma membrane. Biochimie 2014; 107 Pt A:43-50. [DOI: 10.1016/j.biochi.2014.09.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 09/09/2014] [Indexed: 12/27/2022]
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217
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Queisser MA, Dada LA, Deiss-Yehiely N, Angulo M, Zhou G, Kouri FM, Knab LM, Liu J, Stegh AH, DeCamp MM, Budinger GRS, Chandel NS, Ciechanover A, Iwai K, Sznajder JI. HOIL-1L functions as the PKCζ ubiquitin ligase to promote lung tumor growth. Am J Respir Crit Care Med 2014; 190:688-98. [PMID: 25118570 DOI: 10.1164/rccm.201403-0463oc] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
RATIONALE Protein kinase C zeta (PKCζ) has been reported to act as a tumor suppressor. Deletion of PKCζ in experimental cancer models has been shown to increase tumor growth. However, the mechanisms of PKCζ down-regulation in cancerous cells have not been previously described. OBJECTIVES To determine the molecular mechanisms that lead to decreased PKCζ expression and thus increased survival in cancer cells and tumor growth. METHODS The levels of expression of heme-oxidized IRP2 ubiquitin ligase 1L (HOIL-1L), HOIL-1-interacting protein (HOIP), Shank-associated RH domain-interacting protein (SHARPIN), and PKCζ were analyzed by Western blot and/or quantitative real-time polymerase chain reaction in different cell lines. Coimmunoprecipitation experiments were used to demonstrate the interaction between HOIL-1L and PKCζ. Ubiquitination was measured in an in vitro ubiquitination assay and by Western blot with specific antibodies. The role of hypoxia-inducible factor (HIF) was determined by gain/loss-of-function experiments. The effect of HOIL-1L expression on cell death was investigated using RNA interference approaches in vitro and on tumor growth in mice models. Increased HOIL-1L and decreased PKCζ expression was assessed in lung adenocarcinoma and glioblastoma multiforme and documented in several other cancer types by oncogenomic analysis. MEASUREMENTS AND MAIN RESULTS Hypoxia is a hallmark of rapidly growing solid tumors. We found that during hypoxia, PKCζ is ubiquitinated and degraded via the ubiquitin ligase HOIL-1L, a component of the linear ubiquitin chain assembly complex (LUBAC). In vitro ubiquitination assays indicate that HOIL-1L ubiquitinates PKCζ at Lys-48, targeting it for proteasomal degradation. In a xenograft tumor model and lung cancer model, we found that silencing of HOIL-1L increased the abundance of PKCζ and decreased the size of tumors, suggesting that lower levels of HOIL-1L promote survival. Indeed, mRNA transcript levels of HOIL-1L were elevated in tumor of patients with lung adenocarcinoma, and in a lung adenocarcinoma tissue microarray the levels of HOIL-1L were associated with high-grade tumors. Moreover, we found that HOIL-1L expression was regulated by HIFs. Interestingly, the actions of HOIL-1L were independent of LUBAC. CONCLUSIONS These data provide first evidence of a mechanism of cancer cell adaptation to hypoxia where HIFs regulate HOIL-1L, which targets PKCζ for degradation to promote tumor survival. We provided a proof of concept that silencing of HOIL-1L impairs lung tumor growth and that HOIL-1L expression predicts survival rate in cancer patients suggesting that HOIL-1L is an attractive target for cancer therapy.
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218
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Differential targeting of cPKC and nPKC decodes and regulates Ca2+ and lipid signalling. Biochem Soc Trans 2014; 42:1538-42. [DOI: 10.1042/bst20140239] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Protein kinases C (PKCs) are ubiquitously expressed and play critical roles in a plethora of physiological and pathophysiological processes. Owing to PKCs’ highly conserved phosphorylation consensus sequence, it has been difficult to distinguish the role of individual PKC isoforms. Recently, the identification of novel membrane targeting via subcellularly targeted diacylglycerol production found for novel PKCs (nPKCs), together with a characterization of their putative functions, has shed new light on the specific roles of individual PKCs in cellular processes.
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219
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Zhou X, Shen L, Parris T, Huang J, Yi B, Helou K, Chen C. Regulation of the viability of Nf1 deficient cells by PKC isoforms. Oncotarget 2014; 5:10709-17. [PMID: 25301738 PMCID: PMC4279404 DOI: 10.18632/oncotarget.2531] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 09/25/2014] [Indexed: 11/25/2022] Open
Abstract
Suppression of protein kinase C (PKC) is known to be synthetically lethal with ras mutations in various types of cancer cells. The studies also showed that blockade of PKC affected the viability of Nf1 deficient cells. Since PKC family consists of more than 10 isoforms, our study aimed at identifying which isoform(s) played the crucial role in sensitizing Nf1 deficient cells to apoptosis. Using genetic and chemical PKC inhibitors, we demonstrated that the concurrent inhibition of PKC α and β induced Nf1 deficient ST or 96.2 cells, but not SNF02.2 cells with a normal Nf1 or ST cells ectopically expressing Nf1 effective domain gene, to apoptosis. In this process, PKC δ in Nf1 deficient cells, but not in ST/Nf1 cells, was upregulated and translocated to the nucleus. Furthermore, caspase 3 was cleaved and cytochrome c was released to the cytosol. Thus, it appeared that PKC δ and α/β are the crucial components for sustaining the aberrant Ras signaling and further viability of Nf1 deficient cells. The abrogation of these two isoforms activated their opponent PKC δ for switching on the caspase 3-governed apoptotic machinery.
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Affiliation(s)
- Xiaodong Zhou
- Center for Drug Discovery, Northeastern University, Boston, USA. The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Ling Shen
- Center for Drug Discovery, Northeastern University, Boston, USA
| | - Toshima Parris
- The Institute of Clinical Sciences, Gothenburg University, Gothenburg, SE
| | - Junchi Huang
- Center for Drug Discovery, Northeastern University, Boston, USA
| | - Bo Yi
- Center for Drug Discovery, Northeastern University, Boston, USA. The Jiangxi Province Tumor Hospital, Nanchang, China
| | - Khalil Helou
- The Institute of Clinical Sciences, Gothenburg University, Gothenburg, SE
| | - Changyan Chen
- Center for Drug Discovery, Northeastern University, Boston, USA. The Institute of Clinical Sciences, Gothenburg University, Gothenburg, SE
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220
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Rajagopal S, Fields BL, Kamatchi GL. Contribution of protein kinase Cα in the stimulation of insulin by the down-regulation of Cavβ subunits. Endocrine 2014; 47:463-71. [PMID: 24452871 PMCID: PMC4176602 DOI: 10.1007/s12020-013-0149-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 12/14/2013] [Indexed: 12/23/2022]
Abstract
Voltage-gated calcium (Cav) channels and protein kinase C (PKC) isozymes are involved in insulin secretion. In addition, Cavβ, one of the auxiliary subunits of Cav channels, also regulates the secretion of insulin as knockout of Cavβ3 (β3(-/-)) subunits in mice led to efficient glucose homeostasis and increased insulin levels. We examined whether other types of Cavβ subunits also have similar properties. In this regard, we used small interfering RNA (siRNA) of these subunits (20 μg each) to down-regulate them and examined blood glucose, serum insulin and PKC translocation in isolated pancreatic β cells of mice. While the down-regulation of Cavβ2 and β3 subunits increased serum insulin levels and caused efficient glucose homeostasis, the down-regulation of Cavβ1 and β4 subunits failed to affect both these parameters. Examination of PKC isozymes in the pancreatic β-cells of Cavβ2- or β3 siRNA-injected mice showed that three PKC isozymes, viz., PKC α, βII and θ, translocated to the membrane. This suggests that when present, Cavβ2 and β3 subunits inhibited PKC activation. Among these three isozymes, only PKCα siRNA inhibited insulin and increased glucose concentrations. It is possible that the activation of PKCs βII and θ is not sufficient for the release of insulin and PKCα is the mediator of insulin secretion under the control of Cavβ subunits. Since Cavβ subunits are present intracellularly, it is possible that they (1) inhibited the translocation of PKC isozymes to the membrane and (2) decreased the interaction between Cav channels and PKC isozymes and thus the secretion of insulin.
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Affiliation(s)
- Senthilkumar Rajagopal
- Department of Zoology, Nizam College, Osmania University, Hyderabad, 500001, Andhra Pradesh, India
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221
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Rajagopal S, Fields B, Burton B, On C, Reeder A, Kamatchi G. Inhibition of protein kinase C (PKC) response of voltage-gated calcium (Cav)2.2 channels expressed in Xenopus oocytes by Cavβ subunits. Neuroscience 2014; 280:1-9. [DOI: 10.1016/j.neuroscience.2014.08.049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 08/27/2014] [Accepted: 08/28/2014] [Indexed: 01/12/2023]
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222
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de Jong APH, Fioravante D. Translating neuronal activity at the synapse: presynaptic calcium sensors in short-term plasticity. Front Cell Neurosci 2014; 8:356. [PMID: 25400547 PMCID: PMC4212674 DOI: 10.3389/fncel.2014.00356] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 10/09/2014] [Indexed: 01/03/2023] Open
Abstract
The complex manner in which patterns of presynaptic neural activity are translated into short-term plasticity (STP) suggests the existence of multiple presynaptic calcium (Ca(2+)) sensors, which regulate the amplitude and time-course of STP and are the focus of this review. We describe two canonical Ca(2+)-binding protein domains (C2 domains and EF-hands) and define criteria that need to be met for a protein to qualify as a Ca(2+) sensor mediating STP. With these criteria in mind, we discuss various forms of STP and identify established and putative Ca(2+) sensors. We find that despite the multitude of proposed sensors, only three are well established in STP: Munc13, protein kinase C (PKC) and synaptotagmin-7. For putative sensors, we pinpoint open questions and potential pitfalls. Finally, we discuss how the molecular properties and modes of action of Ca(2+) sensors can explain their differential involvement in STP and shape net synaptic output.
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Affiliation(s)
| | - Diasynou Fioravante
- Department of Neurobiology, Physiology and Behavior, Center for Neuroscience, University of California Davis Davis, CA, USA
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223
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Bastianetto S, Ménard C, Quirion R. Neuroprotective action of resveratrol. Biochim Biophys Acta Mol Basis Dis 2014; 1852:1195-201. [PMID: 25281824 DOI: 10.1016/j.bbadis.2014.09.011] [Citation(s) in RCA: 249] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/09/2014] [Accepted: 09/16/2014] [Indexed: 11/30/2022]
Abstract
Low-to-moderate red wine consumption appeared to reduce age-related neurological disorders including macular degeneration, stroke, and cognitive deficits with or without dementia. Resveratrol has been considered as one of the key ingredients responsible for the preventive action of red wine since the stilbene displays a neuroprotective action in various models of toxicity. Besides its well documented free radical scavenging and anti-inflammatory properties, resveratrol has been shown to increase the clearance of beta-amyloid, a key feature of Alzheimer's disease, and to modulate intracellular effectors associated with oxidative stress (e.g. heme oxygenase), neuronal energy homeostasis (e.g. AMP kinase), program cell death (i.e. AIF) and longevity (i.e. sirtuins). This article summarizes the most recent findings on mechanisms of action involved in the protective effects of this multi target polyphenol, and discusses its possible roles in the prevention of various age-related neurological disorders. This article is part of a Special Issue entitled: Resveratrol: Challenges in translating pre-clinical findings to improved patient outcomes.
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Affiliation(s)
- Stéphane Bastianetto
- Douglas Mental Health University Institute, McGill University, Montreal, QC H4H 1R3, Canada
| | - Caroline Ménard
- Douglas Mental Health University Institute, McGill University, Montreal, QC H4H 1R3, Canada; Department of Psychiatry, McGill University, Montreal, QC H3A 1A1, Canada; Laboratory of Neuroendocrinology of Aging, Centre Hospitalier de l'Université de Montréal Research Center, Montreal, QC H2X 0A9, Canada; Department of Medicine, University of Montreal, Montreal, QC H3T 1J4, Canada
| | - Rémi Quirion
- Douglas Mental Health University Institute, McGill University, Montreal, QC H4H 1R3, Canada; Department of Psychiatry, McGill University, Montreal, QC H3A 1A1, Canada.
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224
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Boyle GM, D'Souza MMA, Pierce CJ, Adams RA, Cantor AS, Johns JP, Maslovskaya L, Gordon VA, Reddell PW, Parsons PG. Intra-lesional injection of the novel PKC activator EBC-46 rapidly ablates tumors in mouse models. PLoS One 2014; 9:e108887. [PMID: 25272271 PMCID: PMC4182759 DOI: 10.1371/journal.pone.0108887] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 09/04/2014] [Indexed: 11/18/2022] Open
Abstract
Intra-lesional chemotherapy for treatment of cutaneous malignancies has been used for many decades, allowing higher local drug concentrations and less toxicity than systemic agents. Here we describe a novel diterpene ester, EBC-46, and provide preclinical data supporting its use as an intra-lesional treatment. A single injection of EBC-46 caused rapid inflammation and influx of blood, followed by eschar formation and rapid tumor ablation in a range of syngeneic and xenograft models. EBC-46 induced oxidative burst from purified human polymorphonuclear cells, which was prevented by the Protein Kinase C inhibitor bisindolylmaleimide-1. EBC-46 activated a more specific subset of PKC isoforms (PKC-βI, -βII, -α and -γ) compared to the structurally related phorbol 12-myristate 13-acetate (PMA). Although EBC-46 showed threefold less potency for inhibiting cell growth than PMA in vitro, it was more effective for cure of tumors in vivo. No viable tumor cells were evident four hours after injection by ex vivo culture. Pharmacokinetic profiles from treated mice indicated that EBC-46 was retained preferentially within the tumor, and resulted in significantly greater local responses (erythema, oedema) following intra-lesional injection compared with injection into normal skin. The efficacy of EBC-46 was reduced by co-injection with bisindolylmaleimide-1. Loss of vascular integrity following treatment was demonstrated by an increased permeability of endothelial cell monolayers in vitro and by CD31 immunostaining of treated tumors in vivo. Our results demonstrate that a single intra-lesional injection of EBC-46 causes PKC-dependent hemorrhagic necrosis, rapid tumor cell death and ultimate cure of solid tumors in pre-clinical models of cancer.
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Affiliation(s)
- Glen M. Boyle
- Drug Discovery/Cancer Drug Mechanisms Group, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
- * E-mail:
| | - Marjorie M. A. D'Souza
- Drug Discovery/Cancer Drug Mechanisms Group, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
- School of Medicine, University of Queensland, Brisbane, Queensland, Australia
| | - Carly J. Pierce
- Drug Discovery/Cancer Drug Mechanisms Group, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Ryan A. Adams
- Drug Discovery/Cancer Drug Mechanisms Group, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
- School of Medicine, University of Queensland, Brisbane, Queensland, Australia
- Department of Otolaryngology, Head and Neck Surgery, Princess Alexandra Hospital, Brisbane, Queensland, Australia
| | - Aaron S. Cantor
- Drug Discovery/Cancer Drug Mechanisms Group, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Jenny P. Johns
- Drug Discovery/Cancer Drug Mechanisms Group, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Lidia Maslovskaya
- Drug Discovery/Cancer Drug Mechanisms Group, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | | | | | - Peter G. Parsons
- Drug Discovery/Cancer Drug Mechanisms Group, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
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225
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Ren J, Li XR, Liu PC, Cai MJ, Liu W, Wang JX, Zhao XF. G-protein αq participates in the steroid hormone 20-hydroxyecdysone nongenomic signal transduction. J Steroid Biochem Mol Biol 2014; 144 Pt B:313-23. [PMID: 25125388 DOI: 10.1016/j.jsbmb.2014.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 08/02/2014] [Accepted: 08/08/2014] [Indexed: 11/22/2022]
Abstract
The nuclear receptor-mediated genomic pathways of the animal steroid hormones are well known. However, the cell membrane receptor-mediated nongenomic pathways of the animal steroid hormones are little understood. In this study, we report the participation of a G-protein alpha q (Gαq)(1) subunit in the 20E nongenomic pathway in the cell membrane and regulating gene expression during molting and metamorphosis in a lepidopteran insect, Helicoverpa armigera. 20E-induced phosphorylation of Gαq was detected using two-dimensional electrophoresis techniques. Knockdown of Gαq by injecting double-stranded RNA suppressed the development of larvae, delayed metamorphosis, and inhibited 20E-induced gene expression. Gαq was distributed throughout the cell, and migrated toward the plasma membrane upon 20E induction. Gαq was necessary in the 20E-induced intracellular Ca(2+) release and extracellular Ca(2+) influx. The protein kinase C (PKC) inhibitor could repress 20E-induced phosphorylation of cyclin-dependent kinase 10 (CDK10) and transcription factor ultraspiracle (USP1). PKC inhibitor could repress the Gαq phosphorylation and membrane trafficking. These results suggest that Gαq participates in 20E signaling in the cell membrane at the pre-genomic stage by modulating the increase of the intracellular Ca(2+) and phosphorylation of CDK10 and USP1 in 20E transcription complex to regulate gene transcription.
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Affiliation(s)
- Jing Ren
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Jinan 250100, China
| | - Xiang-Ru Li
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Jinan 250100, China
| | - Peng-Cheng Liu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Jinan 250100, China
| | - Mei-Juan Cai
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Jinan 250100, China
| | - Wen Liu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Jinan 250100, China
| | - Jin-Xing Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Jinan 250100, China
| | - Xiao-Fan Zhao
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Jinan 250100, China.
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226
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Bowton E, Saunders C, Reddy IA, Campbell NG, Hamilton PJ, Henry LK, Coon H, Sakrikar D, Veenstra-VanderWeele JM, Blakely RD, Sutcliffe J, Matthies HJG, Erreger K, Galli A. SLC6A3 coding variant Ala559Val found in two autism probands alters dopamine transporter function and trafficking. Transl Psychiatry 2014; 4:e464. [PMID: 25313507 PMCID: PMC4350523 DOI: 10.1038/tp.2014.90] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 08/11/2014] [Accepted: 08/12/2014] [Indexed: 12/12/2022] Open
Abstract
Emerging evidence associates dysfunction in the dopamine (DA) transporter (DAT) with the pathophysiology of autism spectrum disorder (ASD). The human DAT (hDAT; SLC6A3) rare variant with an Ala to Val substitution at amino acid 559 (hDAT A559V) was previously reported in individuals with bipolar disorder or attention-deficit hyperactivity disorder (ADHD). We have demonstrated that this variant is hyper-phosphorylated at the amino (N)-terminal serine (Ser) residues and promotes an anomalous DA efflux phenotype. Here, we report the novel identification of hDAT A559V in two unrelated ASD subjects and provide the first mechanistic description of its impaired trafficking phenotype. DAT surface expression is dynamically regulated by DAT substrates including the psychostimulant amphetamine (AMPH), which causes hDAT trafficking away from the plasma membrane. The integrity of DAT trafficking directly impacts DA transport capacity and therefore dopaminergic neurotransmission. Here, we show that hDAT A559V is resistant to AMPH-induced cell surface redistribution. This unique trafficking phenotype is conferred by altered protein kinase C β (PKCβ) activity. Cells expressing hDAT A559V exhibit constitutively elevated PKCβ activity, inhibition of which restores the AMPH-induced hDAT A559V membrane redistribution. Mechanistically, we link the inability of hDAT A559V to traffic in response to AMPH to the phosphorylation of the five most distal DAT N-terminal Ser. Mutation of these N-terminal Ser to Ala restores AMPH-induced trafficking. Furthermore, hDAT A559V has a diminished ability to transport AMPH, and therefore lacks AMPH-induced DA efflux. Pharmacological inhibition of PKCβ or Ser to Ala substitution in the hDAT A559V background restores AMPH-induced DA efflux while promoting intracellular AMPH accumulation. Although hDAT A559V is a rare variant, it has been found in multiple probands with neuropsychiatric disorders associated with imbalances in DA neurotransmission, including ADHD, bipolar disorder, and now ASD. These findings provide valuable insight into a new cellular phenotype (altered hDAT trafficking) supporting dysregulated DA function in these disorders. They also provide a novel potential target (PKCβ) for therapeutic interventions in individuals with ASD.
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Affiliation(s)
- E Bowton
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - C Saunders
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - I A Reddy
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - N G Campbell
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - P J Hamilton
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - L K Henry
- Department of Basic Sciences, University of North Dakota, Grand Forks, ND, USA
| | - H Coon
- Department of Psychiatry, University of Utah, Salt Lake City, UT, USA
| | - D Sakrikar
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - J M Veenstra-VanderWeele
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Psychiatry, Vanderbilt University Medical Center, Nashville, TN, USA
| | - R D Blakely
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - J Sutcliffe
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Psychiatry, Vanderbilt University Medical Center, Nashville, TN, USA
| | - H J G Matthies
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,N-PISA Neuroscience Program In Substance Abuse, Vanderbilt University Medical Center, Nashville, TN, USA,Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, 465 21st Avenue South, MRB3, Room 7124, Nashville, TN 37232, USA E-mail: or
| | - K Erreger
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,N-PISA Neuroscience Program In Substance Abuse, Vanderbilt University Medical Center, Nashville, TN, USA,Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, 465 21st Avenue South, MRB3, Room 7124, Nashville, TN 37232, USA E-mail: or
| | - A Galli
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,N-PISA Neuroscience Program In Substance Abuse, Vanderbilt University Medical Center, Nashville, TN, USA,Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, 465 21st Avenue South, MRB3, Room 7130A, Nashville, TN 37232, USA. E-mail:
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227
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Szilagyi K, Meijer AB, Neele AE, Verkuijlen P, Leitges M, Dabernat S, Förster-Waldl E, Boztug K, Belot A, Kuijpers TW, Kraal G, de Winther MPJ, van den Berg TK. PKCδ is dispensible for oxLDL uptake and foam cell formation by human and murine macrophages. Cardiovasc Res 2014; 104:467-76. [DOI: 10.1093/cvr/cvu213] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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228
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Wender PA, Staveness D. Improved protein kinase C affinity through final step diversification of a simplified salicylate-derived bryostatin analog scaffold. Org Lett 2014; 16:5140-3. [PMID: 25238640 PMCID: PMC4334251 DOI: 10.1021/ol502492b] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
![]()
Bryostatin
1, in clinical
trials or preclinical development for cancer, Alzheimer’s disease,
and a first-of-its-kind strategy for HIV/AIDS eradication, is neither
readily available nor optimally suited for clinical use. In preceding
work, we disclosed a new class of simplified bryostatin analogs designed
for ease of access and tunable activity. Here we describe a final
step diversification strategy that provides, in only 25 synthetic
steps, simplified and tunable analogs with bryostatin-like PKC modulatory
activities.
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Affiliation(s)
- Paul A Wender
- Departments of Chemistry and Chemical and Systems Biology, Stanford University , Stanford, California 94305, United States
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229
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Wender PA, Nakagawa Y, Near KE, Staveness D. Computer-guided design, synthesis, and protein kinase C affinity of a new salicylate-based class of bryostatin analogs. Org Lett 2014; 16:5136-9. [PMID: 25238583 PMCID: PMC4334246 DOI: 10.1021/ol502491f] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
Bryostatin 1 is in
clinical trials for the treatment of cancer
and Alzheimer’s disease and is a candidate for a first-in-class
approach to HIV/AIDS eradication. It is neither readily available
nor optimally suited for clinical use. Using a function oriented synthesis
strategy, a new class of bryostatin-inspired analogs was designed
with a simplified salicylate-derived subunit, enabling step-economical
synthesis (23 total steps) of agents exhibiting bryostatin-like affinity
to protein kinase C (PKC).
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Affiliation(s)
- Paul A Wender
- Departments of Chemistry and Chemical and Systems Biology, Stanford University , Stanford, California 94305, United States
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230
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Abstract
Protein kinases C (PKCs) are a family of serine/threonine kinases which act as key regulators in cell cycle progression and differentiation. Studies of the involvement of PKCs in cell proliferation showed that their role is dependent on cell models, cell cycle phases, timing of activation and localization. Indeed, PKCs can positively and negatively act on it, regulating entry, progression and exit from the cell cycle. In particular, the targets of PKCs resulted to be some of the key proteins involved in the cell cycle including cyclins, cyclin-dependent kinases (Cdks), Cip/Kip inhibitors and lamins. Several findings described roles for PKCs in the regulation of G1/S and G2/M checkpoints. As a matter of fact, data from independent laboratories demonstrated PKC-related modulations of cyclins D, leading to effects on the G1/S transition and differentiation of different cell lines. Moreover, interesting data were published on PKC-mediated phosphorylation of lamins. In addition, PKC isoenzymes can accumulate in the nuclei, attracted by different stimuli including diacylglycerol (DAG) fluctuations during cell cycle progression, and target lamins, leading to their disassembly at mitosis. In the present paper, we briefly review how PKCs could regulate cell proliferation and differentiation affecting different molecules related to cell cycle progression.
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231
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Anwer MS. Role of protein kinase C isoforms in bile formation and cholestasis. Hepatology 2014; 60:1090-7. [PMID: 24700589 PMCID: PMC4141907 DOI: 10.1002/hep.27088] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 02/13/2014] [Indexed: 12/11/2022]
Abstract
Transhepatic solute transport provides the osmotic driving force for canalicular bile formation. Choleretic and cholestatic agents affect bile formation, in part, by altering plasma membrane localizations of transporters involved in bile formation. These short-term dynamic changes in transporter location are highly regulated posttranslational events requiring various cellular signaling pathways. Interestingly, both choleretic and cholestatic agents activate the same intracellular signaling kinases, such as phosphoinositide-3-kinase (PI3K), protein kinase C (PKC), and mitogen-activated protein kinase (MAPK). An emerging theme is that choleretic and cholestatic effects may be mediated by different isoforms of these kinases. This is most evident for PKC-mediated regulation of plasma membrane localization of Na+-taurocholate cotransporting polypeptide (NTCP) and multidrug resistance-associated protein 2 (MRP2) by conventional PKCα (cPKCα), novel PKCδ (nPKCδ), nPKCε, and atypical PKCζ (aPKCζ). aPKCζ may mediate choleretic effects by inserting NTCP into the plasma membrane, and nPKCε may mediate cholestatic effects by retrieving MRP2 from the plasma membrane. On the other hand, cPKCα and nPKCδ may be involved in choleretic, cholestatic, and anticholestatic effects by inserting, retrieving, and inhibiting retrieval of transporters, respectively. The effects of PKC isoforms may be mediated by phosphorylation of the transporters, actin binding proteins (radixin and myristoylated alanine-rich C kinase substrate), and Rab proteins. Human NTCP plays an important role in the entry of hepatitis B and D viruses into hepatocytes and consequent infection. Thus, PKCs, by regulating NTCP trafficking, may also play an important role in hepatic viral infections.
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Affiliation(s)
- M Sawkat Anwer
- Department of Biomedical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, MA
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232
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Davis TA, Loos B, Engelbrecht AM. AHNAK: the giant jack of all trades. Cell Signal 2014; 26:2683-93. [PMID: 25172424 DOI: 10.1016/j.cellsig.2014.08.017] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 08/08/2014] [Accepted: 08/18/2014] [Indexed: 12/19/2022]
Abstract
The nucleoprotein AHNAK is an unusual and somewhat mysterious scaffolding protein characterised by its large size of approximately 700 kDa. Several aspects of this protein remain uncertain, including its exact molecular function and regulation on both the gene and protein levels. Various studies have attempted to annotate AHNAK and, notably, protein interaction and expression analyses have contributed greatly to our current understanding of the protein. The implicated biological processes are, however, very diverse, ranging from a role in the formation of the blood-brain barrier, cell architecture and migration, to the regulation of cardiac calcium channels and muscle membrane repair. In addition, recent evidence suggests that AHNAK might be yet another accomplice in the development of tumour metastasis. This review will discuss the different functional roles of AHNAK, highlighting recent advancements that have added foundation to the proposed roles while identifying ties between them. Implications for related fields of research are noted and suggestions for future research that will assist in unravelling the function of AHNAK are offered.
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Affiliation(s)
- T A Davis
- Department of Physiological Sciences, University of Stellenbosch, Mike de Vries Building, c/o Merriman Avenue and Bosman Street, Stellenbosch 7600, South Africa.
| | - B Loos
- Department of Physiological Sciences, University of Stellenbosch, Mike de Vries Building, c/o Merriman Avenue and Bosman Street, Stellenbosch 7600, South Africa
| | - A-M Engelbrecht
- Department of Physiological Sciences, University of Stellenbosch, Mike de Vries Building, c/o Merriman Avenue and Bosman Street, Stellenbosch 7600, South Africa
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233
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Kukkonen JP, Leonard CS. Orexin/hypocretin receptor signalling cascades. Br J Pharmacol 2014; 171:314-31. [PMID: 23902572 DOI: 10.1111/bph.12324] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 07/18/2013] [Accepted: 07/28/2013] [Indexed: 12/16/2022] Open
Abstract
Orexin (hypocretin) peptides and their two known G-protein-coupled receptors play essential roles in sleep-wake control and powerfully influence other systems regulating appetite/metabolism, stress and reward. Consequently, drugs that influence signalling by these receptors may provide novel therapeutic opportunities for treating sleep disorders, obesity and addiction. It is therefore critical to understand how these receptors operate, the nature of the signalling cascades they engage and their physiological targets. In this review, we evaluate what is currently known about orexin receptor signalling cascades, while a sister review (Leonard & Kukkonen, this issue) focuses on tissue-specific responses. The evidence suggests that orexin receptor signalling is multifaceted and is substantially more diverse than originally thought. Indeed, orexin receptors are able to couple to members of at least three G-protein families and possibly other proteins, through which they regulate non-selective cation channels, phospholipases, adenylyl cyclase, and protein and lipid kinases. In the central nervous system, orexin receptors produce neuroexcitation by postsynaptic depolarization via activation of non-selective cation channels, inhibition of K⁺ channels and activation of Na⁺/Ca²⁺ exchange, but they also can stimulate the release of neurotransmitters by presynaptic actions and modulate synaptic plasticity. Ca²⁺ signalling is also prominently influenced by these receptors, both via the classical phospholipase C-Ca²⁺ release pathway and via Ca²⁺ influx, mediated by several pathways. Upon longer-lasting stimulation, plastic effects are observed in some cell types, while others, especially cancer cells, are stimulated to die. Thus, orexin receptor signals appear highly tunable, depending on the milieu in which they are operating.
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Affiliation(s)
- J P Kukkonen
- Biochemistry and Cell Biology, Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
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234
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Zhang P, Goodrich C, Fu C, Dong C. Melanoma upregulates ICAM-1 expression on endothelial cells through engagement of tumor CD44 with endothelial E-selectin and activation of a PKCα-p38-SP-1 pathway. FASEB J 2014; 28:4591-609. [PMID: 25138157 DOI: 10.1096/fj.11-202747] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cancer metastasis involves multistep adhesive interactions between tumor cells (TCs) and endothelial cells (ECs), but the molecular mechanisms of intercellular communication in the tumor microenvironment remain elusive. Using static and flow coculture systems in conjunction with flow cytometry, we discovered that certain receptors on the ECs are upregulated on melanoma cell adhesion. Direct contact but not separate coculture between human umbilical endothelial cells (HUVECs) and a human melanoma cell line (Lu1205) increased intercellular adhesion molecule 1 (ICAM-1) and E-selectin expression on HUVECs by 3- and 1.5-fold, respectively, compared with HUVECs alone. The nonmetastatic cell line WM35 failed to promote ICAM-1 expression changes in HUVECs on contact. Enzyme-linked immunosorbent assay (ELISA) revealed that EC-TC contact has a synergistic effect on the expression of the cytokines interleukin (IL)-8, IL-6, and growth-related oncogene α (Gro-α). By using E-selectin cross-linking and beads coated with CD44 immunopurified from Lu1205 cells, we showed that CD44/selectin ligation was responsible for the ICAM-1 up-regulation on HUVECs. Protein kinase Cα (PKC-α) activation was found to be the downstream target of the CD44/selectin-initiated signaling, as ICAM-1 elevation was inhibited by siRNA targeting PKCα or a dominant negative form of PKCα (PKCα DN). Western blot analysis and electrophoretic mobility shift assays (EMSAs) showed that TC-EC contact mediated p38 phosphorylation and binding of the transcription factor SP-1 to its regulation site. In conclusion, CD44/selectin binding signals ICAM-1 up-regulation on the EC surface through a PKCα-p38-SP-1 pathway, which further enhances melanoma cell adhesion to ECs during metastasis.
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Affiliation(s)
- Pu Zhang
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Chris Goodrich
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Changliang Fu
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Cheng Dong
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
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235
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Stewart MD, Cole TR, Igumenova TI. Interfacial partitioning of a loop hinge residue contributes to diacylglycerol affinity of conserved region 1 domains. J Biol Chem 2014; 289:27653-64. [PMID: 25124034 DOI: 10.1074/jbc.m114.585570] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Conventional and novel isoenzymes of PKC are activated by the membrane-embedded second messenger diacylglycerol (DAG) through its interactions with the C1 regulatory domain. The affinity of C1 domains to DAG varies considerably among PKCs. To gain insight into the origin of differential DAG affinities, we conducted high-resolution NMR studies of C1B domain from PKCδ (C1Bδ) and its W252Y variant. The W252Y mutation was previously shown to render C1Bδ less responsive to DAG (Dries, D. R., Gallegos, L. L., and Newton, A. C. (2007) A single residue in the C1 domain sensitizes novel protein kinase C isoforms to cellular diacylglycerol production. J. Biol. Chem. 282, 826-830) and thereby emulate the behavior of C1B domains from conventional PKCs that have a conserved Tyr at the equivalent position. Our data revealed that W252Y mutation did not perturb the conformation of C1Bδ in solution but significantly reduced its propensity to partition into a membrane-mimicking environment in the absence of DAG. Using detergent micelles doped with a paramagnetic lipid, we determined that both the residue identity at position 252 and complexation with diacylglycerol influence the geometry of C1Bδ-micelle interactions. In addition, we identified the C-terminal helix α1 of C1Bδ as an interaction site with the head groups of phosphatidylserine, a known activator of PKCδ. Taken together, our studies (i) reveal the identities of C1Bδ residues involved in interactions with membrane-mimicking environment, DAG, and phosphatidylserine, as well as the affinities associated with each event and (ii) suggest that the initial ligand-independent membrane recruitment of C1B domains, which is greatly facilitated by the interfacial partitioning of Trp-252, is responsible, at least in part, for the differential DAG affinities.
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Affiliation(s)
- Mikaela D Stewart
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Taylor R Cole
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Tatyana I Igumenova
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
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236
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Ohashi N, Nomura W, Minato N, Tamamura H. Screening for protein kinase C ligands using fluorescence resonance energy transfer. Chem Pharm Bull (Tokyo) 2014; 62:1019-25. [PMID: 25109829 DOI: 10.1248/cpb.c14-00419] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Protein kinase C (PKC) is correlated with cell signaling pathways and also receives attention as a therapeutic target for cancer and Alzheimer-type dementia. The application of Förster/fluorescence resonance energy transfer (FRET) phenomena to detect binding between proteins and small molecules, for example, PKC and its ligands, underlies a fluorescence-based assay method suitable for high-throughput screening. To accelerate studies on PKC functions in processing signals using small molecules and the development of drugs that target PKC, novel methods for the assessment of the PKC binding affinity of compounds are necessary. We previously developed solvatochromic fluorophore-based methods for that assessment. In this study, a novel method for a FRET-based PKC binding assay was developed and is expected to overcome the limitations of solvatochromic fluorophores.
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Affiliation(s)
- Nami Ohashi
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University
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237
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Fioravante D, Chu Y, de Jong AP, Leitges M, Kaeser PS, Regehr WG. Protein kinase C is a calcium sensor for presynaptic short-term plasticity. eLife 2014; 3:e03011. [PMID: 25097249 PMCID: PMC5841930 DOI: 10.7554/elife.03011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 06/24/2014] [Indexed: 01/02/2023] Open
Abstract
In presynaptic boutons, calcium (Ca(2+)) triggers both neurotransmitter release and short-term synaptic plasticity. Whereas synaptotagmins are known to mediate vesicle fusion through binding of high local Ca(2+) to their C2 domains, the proteins that sense smaller global Ca(2+) increases to produce short-term plasticity have remained elusive. Here, we identify a Ca(2+) sensor for post-tetanic potentiation (PTP), a form of plasticity thought to underlie short-term memory. We find that at the functionally mature calyx of Held synapse the Ca(2+)-dependent protein kinase C isoforms α and β are necessary for PTP, and the expression of PKCβ in PKCαβ double knockout mice rescues PTP. Disruption of Ca(2+) binding to the PKCβ C2 domain specifically prevents PTP without impairing other PKCβ-dependent forms of synaptic enhancement. We conclude that different C2-domain-containing presynaptic proteins are engaged by different Ca(2+) signals, and that Ca(2+) increases evoked by tetanic stimulation are sensed by PKCβ to produce PTP.DOI: http://dx.doi.org/10.7554/eLife.03011.001.
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Affiliation(s)
- Diasynou Fioravante
- Department of Neurobiology, Harvard Medical School, Boston, United States Center for Neuroscience, University of California, Davis, Davis, United States
| | - YunXiang Chu
- Department of Neurobiology, Harvard Medical School, Boston, United States
| | - Arthur Ph de Jong
- Department of Neurobiology, Harvard Medical School, Boston, United States
| | - Michael Leitges
- The Biotechnology Center of Oslo, University of Oslo, Oslo, Norway
| | - Pascal S Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, United States
| | - Wade G Regehr
- Department of Neurobiology, Harvard Medical School, Boston, United States
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238
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Abdel-Halim M, Diesel B, Kiemer AK, Abadi AH, Hartmann RW, Engel M. Discovery and optimization of 1,3,5-trisubstituted pyrazolines as potent and highly selective allosteric inhibitors of protein kinase C-ζ. J Med Chem 2014; 57:6513-30. [PMID: 25058929 DOI: 10.1021/jm500521n] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
There is increasing evidence that the atypical protein kinase C, PKCζ, might be a therapeutic target in pulmonary and hepatic inflammatory diseases. However, targeting the highly conserved ATP-binding pocket in the catalytic domain held little promise to achieve selective inhibition. In the present study, we introduce 1,3,5-trisubstituted pyrazolines as potent and selective allosteric PKCζ inhibitors. The rigid scaffold offered many sites for modification, all acting as hot spots for improving activity, and gave rise to sharp structure-activity relationships. Targeting of PKCζ in cells was confirmed by reporter gene assay, transfection assays, and Western blotting. The strongly reduced cell-free and cellular activities toward a PIF-pocket mutant of PKCζ suggested that the inhibitors most likely bound to the PIF-pocket on the kinase catalytic domain. Thus, using a rigidification strategy and by establishing and optimizing multiple molecular interactions with the binding site, we were able to significantly improve the potency of the previously reported PKCζ inhibitors.
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Affiliation(s)
- Mohammad Abdel-Halim
- Pharmaceutical and Medicinal Chemistry, Saarland University , Campus C2.3, D-66123 Saarbrücken, Germany
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239
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Zhang J, Burrington CM, Davenport SK, Johnson AK, Horsman MJ, Chowdhry S, Greene MW. PKCδ regulates hepatic triglyceride accumulation and insulin signaling in Lepr(db/db) mice. Biochem Biophys Res Commun 2014; 450:1619-25. [PMID: 25035929 DOI: 10.1016/j.bbrc.2014.07.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 07/09/2014] [Indexed: 01/08/2023]
Abstract
PKCδ has been linked to key pathophysiological features of non-alcoholic fatty liver disease (NAFLD). Yet, our knowledge of PKCδ's role in NAFLD development and progression in obese models is limited. PKCδ(-/-)/Lepr(db)(/)(db) mice were generated to evaluate key pathophysiological features of NAFLD in mice. Hepatic histology, oxidative stress, apoptosis, gene expression, insulin signaling, and serum parameters were analyzed in Lepr(db)(/)(db) and PKCδ(-/-)/Lepr(db)(/)(db) mice. The absence of PKCδ did not abrogate the development of obesity in Lepr(db)(/)(db) mice. In contrast, serum triglyceride levels and epididymal white adipose tissue weight normalized to body weight were reduced in PKCδ(-/-)/Lepr(db)(/)(db) mice compared Lepr(db)(/)(db) mice. Analysis of insulin signaling in mice revealed that hepatic Akt and GSK3β phosphorylation were strongly stimulated by insulin in PKCδ(-/-)/Lepr(db)(/)(db) compared Lepr(db)(/)(db) mice. PKCδ may be involved in the development of obesity-associated NAFLD by regulating hepatic lipid metabolism and insulin signaling.
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Affiliation(s)
- Jian Zhang
- Boshell Diabetes and Metabolic Disease Research Program, Auburn University, Auburn, AL 36849, United States; College of Human Sciences, Auburn University, Auburn, AL 36849, United States
| | - Christine M Burrington
- Bassett Research Institute, Bassett Medical Center, Bassett Healthcare Network, Cooperstown, NY 13326, United States
| | - Samantha K Davenport
- Department of Pathology, Bassett Medical Center, Bassett Healthcare Network, Cooperstown, NY 13326, United States
| | - Andrew K Johnson
- Bassett Research Institute, Bassett Medical Center, Bassett Healthcare Network, Cooperstown, NY 13326, United States
| | - Melissa J Horsman
- Bassett Research Institute, Bassett Medical Center, Bassett Healthcare Network, Cooperstown, NY 13326, United States
| | - Saleem Chowdhry
- Department of Internal Medicine, Bassett Medical Center, Bassett Healthcare Network, Cooperstown, NY 13326, United States
| | - Michael W Greene
- Boshell Diabetes and Metabolic Disease Research Program, Auburn University, Auburn, AL 36849, United States; College of Human Sciences, Auburn University, Auburn, AL 36849, United States; Bassett Research Institute, Bassett Medical Center, Bassett Healthcare Network, Cooperstown, NY 13326, United States.
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240
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Alcántara-Hernández R, Hernández-Méndez A, García-Sáinz JA. The phosphoinositide-dependent protein kinase 1 inhibitor, UCN-01, induces fragmentation: possible role of metalloproteinases. Eur J Pharmacol 2014; 740:88-96. [PMID: 25016091 DOI: 10.1016/j.ejphar.2014.06.057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 05/28/2014] [Accepted: 06/20/2014] [Indexed: 12/26/2022]
Abstract
Phosphoinositide-dependent protein kinase 1 (PDK1) is a key enzyme, master regulator of cellular proliferation and metabolism; it is considered a key target for pharmacological intervention. Using membranes obtained from DDT1 MF-2 cells, phospho-PDK1 was identified by Western blotting, as two major protein bands of Mr 58-68 kDa. Cell incubation with the PDK1 inhibitor, UCN-01, induced a time- and concentration-dependent decrease in the amount of phospho-PDK1 with a concomitant appearance of a ≈42 kDa phosphorylated fragment. Knocking down PDK1 diminished the amount of phospho-PDK1 detected in membranes, accompanied by similarly decreased fragment generation. UCN-01-induced fragment generation was also observed in membranes from cells stably expressing a myc-tagged PDK1 construct. Other PDK1 inhibitors were also tested: OSU-03012 induced a clear decrease in phospho-PDK1 and increased the presence of the phosphorylated fragment in membrane preparations; in contrast, GSK2334470 and staurosporine induced only marginal increases in the amount of PDK1 fragment. Galardin and batimastat, two metalloproteinase inhibitors, markedly attenuated inhibitor-induced PDK1 fragment generation. Metalloproteinases 2, 3, and 9 co-immunoprecipitated with myc-PDK1 under baseline conditions and this interaction was stimulated by UCN-01; batimastat also markedly diminished this effect of the PDK1 inhibitor. Our results indicate that a series of protein kinase inhibitors, namely UCN-01 and OSU-03012 and to a lesser extent GSK2334470 and staurosporine induce PDK1 fragmentation and suggest that metalloproteinases could participate in this effect.
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Key Words
- Batimastat (BB-94) (CID 5362422). Galardin (GM 6001) (PubChem CID 132519)
- GSK2334470, (3S,6R)-1-[6-(3-amino-1H-indazol-6-yl)-2-(methylamino)-4-pyrimidinyl]-N-cyclohexyl-6-methyl-3-piperidinecarboxamide. ) (PubChem CID 46215815)
- OSU-03012, (2-amino-N-[4-[5-(2-phenanthrenyl)-3-trifluoromethyl)-1H-pyrazol-1-yl]phenyl]-acetamide) (PubChem CID 10027278)
- PDK1
- Protein fragmentation
- Protein kinase
- Protein kinase inhibitor
- Staurosporine (PubChem CID 44259)
- UCN-01
- UCN-01, (7-hydroxystaurosporine (3R*,8S*, 9R*, 10R*,12R*)-2,3,9,10,11,12-hexahydro-3-hydroxy-9-methoxy-8-methyl-10-(methylamino)-8,12-epoxy-1H, 8H-2,7b,12a-triazadibenzo[a,g]-cyclonona[cde]triden-1-one) (PubChem CID 3078519)
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Affiliation(s)
- Rocío Alcántara-Hernández
- Departamento de Biología Celular y Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-248, México DF 04510, México
| | - Aurelio Hernández-Méndez
- Departamento de Biología Celular y Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-248, México DF 04510, México
| | - J Adolfo García-Sáinz
- Departamento de Biología Celular y Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-248, México DF 04510, México.
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241
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Slupsky JR. Does B cell receptor signaling in chronic lymphocytic leukaemia cells differ from that in other B cell types? SCIENTIFICA 2014; 2014:208928. [PMID: 25101192 PMCID: PMC4102070 DOI: 10.1155/2014/208928] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 06/02/2014] [Indexed: 06/03/2023]
Abstract
Chronic lymphocytic leukaemia (CLL) is an incurable malignancy of mature B cells. CLL is important clinically in Western countries because of its commonality and because of the significant morbidity and mortality associated with the progressive form of this incurable disease. The B cell receptor (BCR) expressed on the malignant cells in CLL contributes to disease pathogenesis by providing signals for survival and proliferation, and the signal transduction pathway initiated by engagement of this receptor is now the target of several therapeutic strategies. The purpose of this review is to outline current understanding of the BCR signal cascade in normal B cells and then question whether this understanding applies to CLL cells. In particular, this review studies the phenomenon of anergy in CLL cells, and whether certain adaptations allow the cells to overcome anergy and allow full BCR signaling to take place. Finally, this review analyzes how BCR signals can be therapeutically targeted for the treatment of CLL.
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Affiliation(s)
- Joseph R. Slupsky
- Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
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242
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Kim HY, Huang BX, Spector AA. Phosphatidylserine in the brain: metabolism and function. Prog Lipid Res 2014; 56:1-18. [PMID: 24992464 DOI: 10.1016/j.plipres.2014.06.002] [Citation(s) in RCA: 220] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 06/18/2014] [Accepted: 06/21/2014] [Indexed: 01/08/2023]
Abstract
Phosphatidylserine (PS) is the major anionic phospholipid class particularly enriched in the inner leaflet of the plasma membrane in neural tissues. PS is synthesized from phosphatidylcholine or phosphatidylethanolamine by exchanging the base head group with serine, and this reaction is catalyzed by phosphatidylserine synthase 1 and phosphatidylserine synthase 2 located in the endoplasmic reticulum. Activation of Akt, Raf-1 and protein kinase C signaling, which supports neuronal survival and differentiation, requires interaction of these proteins with PS localized in the cytoplasmic leaflet of the plasma membrane. Furthermore, neurotransmitter release by exocytosis and a number of synaptic receptors and proteins are modulated by PS present in the neuronal membranes. Brain is highly enriched with docosahexaenoic acid (DHA), and brain PS has a high DHA content. By promoting PS synthesis, DHA can uniquely expand the PS pool in neuronal membranes and thereby influence PS-dependent signaling and protein function. Ethanol decreases DHA-promoted PS synthesis and accumulation in neurons, which may contribute to the deleterious effects of ethanol intake. Improvement of some memory functions has been observed in cognitively impaired subjects as a result of PS supplementation, but the mechanism is unclear.
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Affiliation(s)
- Hee-Yong Kim
- Laboratory of Molecular Signaling, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892-9410, United States.
| | - Bill X Huang
- Laboratory of Molecular Signaling, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892-9410, United States
| | - Arthur A Spector
- Laboratory of Molecular Signaling, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892-9410, United States
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243
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Ressurreição M, De Saram P, Kirk RS, Rollinson D, Emery AM, Page NM, Davies AJ, Walker AJ. Protein kinase C and extracellular signal-regulated kinase regulate movement, attachment, pairing and egg release in Schistosoma mansoni. PLoS Negl Trop Dis 2014; 8:e2924. [PMID: 24921927 PMCID: PMC4055629 DOI: 10.1371/journal.pntd.0002924] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 04/19/2014] [Indexed: 01/22/2023] Open
Abstract
Protein kinases C (PKCs) and extracellular signal-regulated kinases (ERKs) are evolutionary conserved cell signalling enzymes that coordinate cell function. Here we have employed biochemical approaches using ‘smart’ antibodies and functional screening to unravel the importance of these enzymes to Schistosoma mansoni physiology. Various PKC and ERK isotypes were detected, and were differentially phosphorylated (activated) throughout the various S. mansoni life stages, suggesting isotype-specific roles and differences in signalling complexity during parasite development. Functional kinase mapping in adult worms revealed that activated PKC and ERK were particularly associated with the adult male tegument, musculature and oesophagus and occasionally with the oesophageal gland; other structures possessing detectable activated PKC and/or ERK included the Mehlis' gland, ootype, lumen of the vitellaria, seminal receptacle and excretory ducts. Pharmacological modulation of PKC and ERK activity in adult worms using GF109203X, U0126, or PMA, resulted in significant physiological disturbance commensurate with these proteins occupying a central position in signalling pathways associated with schistosome muscular activity, neuromuscular coordination, reproductive function, attachment and pairing. Increased activation of ERK and PKC was also detected in worms following praziquantel treatment, with increased signalling associated with the tegument and excretory system and activated ERK localizing to previously unseen structures, including the cephalic ganglia. These findings support roles for PKC and ERK in S. mansoni homeostasis, and identify these kinase groups as potential targets for chemotherapeutic treatments against human schistosomiasis, a neglected tropical disease of enormous public health significance. Parasitic blood flukes, also called schistosomes, cause human schistosomiasis, a neglected tropical disease and major public health problem in developing countries, especially sub-Saharan Africa. Sustainable control of schistosomiasis is difficult, mainly because the complex life cycle of the parasite involves a freshwater snail host, and the ability of the parasite to evade the immune response of the human host and to survive for many years. Little is yet known about the cellular mechanisms in schistosomes and how they regulate parasite homeostasis, development and behaviour. In this paper, the nature of intracellular signalling by protein kinases C (PKCs) and extracellular signal-regulated kinases (ERKs) in schistosomes is studied and these proteins are found to be vital for the coordination of processes fundamental to parasite survival, such as muscular activity and reproductive function. Our results contribute to an understanding of molecular events regulating schistosome function and identify PKCs and ERKs as possible targets for the development of new chemotherapeutic treatments against schistosomiasis.
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Affiliation(s)
- Margarida Ressurreição
- Molecular Parasitology Laboratory, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, United Kingdom
- Wolfson Wellcome Biomedical Laboratories, Life Sciences Department, Natural History Museum, London, United Kingdom
| | - Paulu De Saram
- Molecular Parasitology Laboratory, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, United Kingdom
- Wolfson Wellcome Biomedical Laboratories, Life Sciences Department, Natural History Museum, London, United Kingdom
| | - Ruth S. Kirk
- Molecular Parasitology Laboratory, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, United Kingdom
| | - David Rollinson
- Wolfson Wellcome Biomedical Laboratories, Life Sciences Department, Natural History Museum, London, United Kingdom
| | - Aidan M. Emery
- Wolfson Wellcome Biomedical Laboratories, Life Sciences Department, Natural History Museum, London, United Kingdom
| | - Nigel M. Page
- Molecular Parasitology Laboratory, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, United Kingdom
| | - Angela J. Davies
- Molecular Parasitology Laboratory, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, United Kingdom
| | - Anthony J. Walker
- Molecular Parasitology Laboratory, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, United Kingdom
- * E-mail:
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244
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Wouters E, Hudson CA, McArdle CA, Bernal AL. Central role for protein kinase C in oxytocin and epidermal growth factor stimulated cyclooxygenase 2 expression in human myometrial cells. BMC Res Notes 2014; 7:357. [PMID: 24916153 PMCID: PMC4057899 DOI: 10.1186/1756-0500-7-357] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 06/03/2014] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Prostaglandins are important mediators of uterine contractility and cervical ripening during labour. Cyclooxygenase-2 (COX-2), also known as prostaglandin-endoperoxide synthase 2, is a rate limiting enzyme involved in the conversion of arachidonic acid into prostaglandins at parturition. In this paper, the pathways underlying agonist-induced cyclooxygenase-2 expression in human myometrial cells were studied. RESULTS Myometrial cells were stimulated with different agonists: oxytocin (OXT), epidermal growth factor (EGF), interleukin-1β (IL1β), and phorbol-12-myristate-13-acetate (PMA) alone and in the presence of specific signalling pathway inhibitors. The nuclear factor kappa-light-chain-enhancer of activated B cells (NFKB) pathway was inhibited by means of the IKK-2 inhibitor TPCA-1. Signalling through extracellular signal-regulated kinases (ERK) was inhibited using the MEK1/2 inhibitor PD-184352. Bisindolylmaleimide-I was used to inhibit protein kinase C (PKC) signalling. COX-2 expression and ERK phosphorylation were measured using immunoblotting.OXT induced COX-2 expression by activating PKC and ERK. EGF increased COX-2 expression via stimulation of PKC, ERK and NFKB. As expected, the pro-inflammatory cytokine IL1β induced COX-2 expression by activating PKC- and NFKB-dependent pathways. Stimulation of PKC directly with PMA provoked strong COX-2 expression. CONCLUSIONS PKC plays a central role in OXT and EGF induced COX-2 expression in human myometrial cells. However, other pathways, notably ERK and NFKB are also involved to an extent which depends on the type of agonist used.
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Affiliation(s)
| | | | | | - Andrés López Bernal
- University of Bristol, School of Clinical Sciences (Obstetrics and Gynaecology), Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, UK.
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245
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Doonachar A, Schoenfeld AR. Expression of PKC iota affects neuronal differentiation of PC12 cells at least partly independent of kinase function. ACTA ACUST UNITED AC 2014; 3:1-13. [PMID: 24910851 DOI: 10.4236/cellbio.2014.31001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Atypical PKC (aPKC) plays a role in establishing cell polarity and has been indicated in neuronal differentiation and polarization, including neurite formation in rat pheochromocytoma PC12 cells, albeit by unclear mechanisms. Here, the role of the aPKC isoform, PKC iota (PKCι), in the early neuronal differentiation of PC12 cells was investigated. NGF-treated PC12 cells with stably expressed exogenous wild-type PKCι showed decreased expression of a neuroendocrine marker, increased expression of a neuronal marker, and increased neurite formation. Stable expression of a kinase- inactive PKCι, but not constitutively active PKCι lacking a regulatory domain, had similar although less potent effects. Pharmacological inhibition of endogenous aPKC kinase activity in parental PC12 cells did not inhibit neurite formation, suggesting that some of the observed effects of PKCι expression on neuronal differentiation are kinase- independent. Interestingly, exogenous expression of wild-type and kinase-inactive PKCι had little effect on overall PKCι activity, but caused a decrease in PKC zeta (PKCζ) kinase activity, suggesting an interplay between the two isoforms that may underlie the observed results. Overall, these findings suggest that in PC12 and perhaps other neuroendocrine precursor cells, PKCι influences an early differentiation decision between the neuroendocrine (chromaffin) and sympathetic neuron cell lineages, potentially by affecting PKCζ function.
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Affiliation(s)
- Alana Doonachar
- Department of Biology, Adelphi University, Garden City, NY, USA
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246
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Kedei N, Chen JQ, Herrmann MA, Telek A, Goldsmith PK, Petersen ME, Keck GE, Blumberg PM. Molecular systems pharmacology: isoelectric focusing signature of protein kinase Cδ provides an integrated measure of its modulation in response to ligands. J Med Chem 2014; 57:5356-69. [PMID: 24906106 PMCID: PMC4216220 DOI: 10.1021/jm500417b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
![]()
Protein
kinase C (PKC), a validated therapeutic target for cancer
chemotherapy, provides a paradigm for assessing structure–activity
relations, where ligand binding has multiple consequences for a target.
For PKC, ligand binding controls not only PKC activation and multiple
phosphorylations but also subcellular localization, affecting subsequent
signaling. Using a capillary isoelectric focusing immunoassay system,
we could visualize a high resolution isoelectric focusing signature
of PKCδ upon stimulation by ligands of the phorbol ester and
bryostatin classes. Derivatives that possessed different physicochemical
characteristics and induced different patterns of biological response
generated different signatures. Consistent with different patterns
of PKCδ localization as one factor linked to these different
signatures, we found different signatures for activated PKCδ
from the nuclear and non-nuclear fractions. We conclude that the capillary
isoelectric focusing immunoassay system may provide a window into
the integrated consequences of ligand binding and thus afford a powerful
platform for compound development.
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Affiliation(s)
- Noemi Kedei
- Laboratory of Cancer Biology and Genetics, ‡Collaborative Protein Technology Resource, Laboratory of Cell Biology, and §Office of Science and Technology Partnerships, Center for Cancer Research, National Cancer Institute , Bethesda, Maryland 20892, United States
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247
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Feeling the hidden mechanical forces in lipid bilayer is an original sense. Proc Natl Acad Sci U S A 2014; 111:7898-905. [PMID: 24850861 DOI: 10.1073/pnas.1313364111] [Citation(s) in RCA: 199] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Life's origin entails enclosing a compartment to hoard material, energy, and information. The envelope necessarily comprises amphipaths, such as prebiotic fatty acids, to partition the two aqueous domains. The self-assembled lipid bilayer comes with a set of properties including its strong anisotropic internal forces that are chemically or physically malleable. Added bilayer stretch can alter force vectors on embedded proteins to effect conformational change. The force-from-lipid principle was demonstrated 25 y ago when stretches opened purified Escherichia coli MscL channels reconstituted into artificial bilayers. This reductionistic exercise has rigorously been recapitulated recently with two vertebrate mechanosensitive K(+) channels (TREK1 and TRAAK). Membrane stretches have also been known to activate various voltage-, ligand-, or Ca(2+)-gated channels. Careful analyses showed that Kv, the canonical voltage-gated channel, is in fact exquisitely sensitive even to very small tension. In an unexpected context, the canonical transient-receptor-potential channels in the Drosophila eye, long presumed to open by ligand binding, is apparently opened by membrane force due to PIP2 hydrolysis-induced changes in bilayer strain. Being the intimate medium, lipids govern membrane proteins by physics as well as chemistry. This principle should not be a surprise because it parallels water's paramount role in the structure and function of soluble proteins. Today, overt or covert mechanical forces govern cell biological processes and produce sensations. At the genesis, a bilayer's response to osmotic force is likely among the first senses to deal with the capricious primordial sea.
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248
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Pal D, Basu A. The unique protein kinase Cη: implications for breast cancer (review). Int J Oncol 2014; 45:493-8. [PMID: 24841225 DOI: 10.3892/ijo.2014.2443] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 02/18/2014] [Indexed: 11/05/2022] Open
Abstract
Deregulation of key signal transduction pathways that govern important cellular processes leads to cancer. The development of effective therapeutics for cancer warrants a comprehensive understanding of the signaling pathways that are deregulated in cancer. The protein kinase C (PKC) family has served as an attractive target for cancer therapy for decades owing to its crucial roles in several cellular processes. PKCη is a novel member of the PKC family that plays critical roles in various cellular processes such as growth, proliferation, differentiation and cell death. The regulation of PKCη appears to be unique compared to other PKC isozymes, and there are conflicting reports regarding its role in cancer. This review focuses on the unique aspects of PKCη in terms of its structure, regulation and subcellular distribution and speculates on how these features could account for its distinct functions. We have also discussed the functional implications of PKCη in cancer with particular emphasis on breast cancer.
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Affiliation(s)
- Deepanwita Pal
- Department of Molecular and Medical Genetics, University of North Texas Health Science Center and Institute for Cancer Research, Fort Worth, TX 76107, USA
| | - Alakananda Basu
- Department of Molecular and Medical Genetics, University of North Texas Health Science Center and Institute for Cancer Research, Fort Worth, TX 76107, USA
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249
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Zhang H, Neimanis S, Lopez-Garcia LA, Arencibia JM, Amon S, Stroba A, Zeuzem S, Proschak E, Stark H, Bauer AF, Busschots K, Jørgensen TJD, Engel M, Schulze JO, Biondi RM. Molecular mechanism of regulation of the atypical protein kinase C by N-terminal domains and an allosteric small compound. ACTA ACUST UNITED AC 2014; 21:754-65. [PMID: 24836908 DOI: 10.1016/j.chembiol.2014.04.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Revised: 03/15/2014] [Accepted: 04/04/2014] [Indexed: 11/30/2022]
Abstract
Protein kinases play important regulatory roles in cells and organisms. Therefore, they are subject to specific and tight mechanisms of regulation that ultimately converge on the catalytic domain and allow the kinases to be activated or inhibited only upon the appropriate stimuli. AGC protein kinases have a pocket in the catalytic domain, the PDK1-interacting fragment (PIF)-pocket, which is a key mediator of the activation. We show here that helix αC within the PIF-pocket of atypical protein kinase C (aPKC) is the target of the interaction with its inhibitory N-terminal domains. We also provide structural evidence that the small compound PS315 is an allosteric inhibitor that binds to the PIF-pocket of aPKC. PS315 exploits the physiological dynamics of helix αC for its binding and allosteric inhibition. The results will support research on allosteric mechanisms and selective drug development efforts against PKC isoforms.
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Affiliation(s)
- Hua Zhang
- Research Group PhosphoSites, Department of Internal Medicine I, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Sonja Neimanis
- Research Group PhosphoSites, Department of Internal Medicine I, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Laura A Lopez-Garcia
- Research Group PhosphoSites, Department of Internal Medicine I, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - José M Arencibia
- Research Group PhosphoSites, Department of Internal Medicine I, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Sabine Amon
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - Adriana Stroba
- Department of Pharmaceutical and Medicinal Chemistry, University of Saarland, 66041 Saarbrücken, Germany
| | - Stefan Zeuzem
- Research Group PhosphoSites, Department of Internal Medicine I, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Ewgen Proschak
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, 60438 Frankfurt, Germany
| | - Holger Stark
- Research Group PhosphoSites, Department of Internal Medicine I, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany; Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, 60438 Frankfurt, Germany
| | - Angelika F Bauer
- Research Group PhosphoSites, Department of Internal Medicine I, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Katrien Busschots
- Research Group PhosphoSites, Department of Internal Medicine I, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Thomas J D Jørgensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - Matthias Engel
- Department of Pharmaceutical and Medicinal Chemistry, University of Saarland, 66041 Saarbrücken, Germany
| | - Jörg O Schulze
- Research Group PhosphoSites, Department of Internal Medicine I, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Ricardo M Biondi
- Research Group PhosphoSites, Department of Internal Medicine I, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
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250
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Wachowicz K, Hermann-Kleiter N, Meisel M, Siegmund K, Thuille N, Baier G. Protein kinase C θ regulates the phenotype of murine CD4+ Th17 cells. PLoS One 2014; 9:e96401. [PMID: 24788550 PMCID: PMC4008503 DOI: 10.1371/journal.pone.0096401] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 04/06/2014] [Indexed: 02/07/2023] Open
Abstract
Protein kinase C θ (PKCθ) is involved in signaling downstream of the T cell antigen receptor (TCR) and is important for shaping effector T cell functions and inflammatory disease development. Acquisition of Th1-like effector features by Th17 cells has been linked to increased pathogenic potential. However, the molecular mechanisms underlying Th17/Th1 phenotypic instability remain largely unknown. In the current study, we address the role of PKCθ in differentiation and function of Th17 cells by using genetic knock-out mice. Implementing in vitro (polarizing T cell cultures) and in vivo (experimental autoimmune encephalomyelitis model, EAE) techniques, we demonstrated that PKCθ-deficient CD4+ T cells show normal Th17 marker gene expression (interleukin 17A/F, RORγt), accompanied by enhanced production of the Th1-typical markers such as interferon gamma (IFN-γ) and transcription factor T-bet. Mechanistically, this phenotype was linked to aberrantly elevated Stat4 mRNA levels in PKCθ−/− CD4+ T cells during the priming phase of Th17 differentiation. In contrast, transcription of the Stat4 gene was suppressed in Th17-primed wild-type cells. This change in cellular effector phenotype was reflected in vivo by prolonged neurological impairment of PKCθ-deficient mice during the course of EAE. Taken together, our data provide genetic evidence that PKCθ is critical for stabilizing Th17 cell phenotype by selective suppression of the STAT4/IFN-γ/T-bet axis at the onset of differentiation.
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Affiliation(s)
- Katarzyna Wachowicz
- Translational Cell Genetics, Department of Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Natascha Hermann-Kleiter
- Translational Cell Genetics, Department of Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Marlies Meisel
- Translational Cell Genetics, Department of Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Kerstin Siegmund
- Translational Cell Genetics, Department of Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Nikolaus Thuille
- Translational Cell Genetics, Department of Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Gottfried Baier
- Translational Cell Genetics, Department of Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria
- * E-mail:
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