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Silnitsky S, Rubin SJS, Zerihun M, Qvit N. An Update on Protein Kinases as Therapeutic Targets-Part I: Protein Kinase C Activation and Its Role in Cancer and Cardiovascular Diseases. Int J Mol Sci 2023; 24:17600. [PMID: 38139428 PMCID: PMC10743896 DOI: 10.3390/ijms242417600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/10/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
Protein kinases are one of the most significant drug targets in the human proteome, historically harnessed for the treatment of cancer, cardiovascular disease, and a growing number of other conditions, including autoimmune and inflammatory processes. Since the approval of the first kinase inhibitors in the late 1990s and early 2000s, the field has grown exponentially, comprising 98 approved therapeutics to date, 37 of which were approved between 2016 and 2021. While many of these small-molecule protein kinase inhibitors that interact orthosterically with the protein kinase ATP binding pocket have been massively successful for oncological indications, their poor selectively for protein kinase isozymes have limited them due to toxicities in their application to other disease spaces. Thus, recent attention has turned to the use of alternative allosteric binding mechanisms and improved drug platforms such as modified peptides to design protein kinase modulators with enhanced selectivity and other pharmacological properties. Herein we review the role of different protein kinase C (PKC) isoforms in cancer and cardiovascular disease, with particular attention to PKC-family inhibitors. We discuss translational examples and carefully consider the advantages and limitations of each compound (Part I). We also discuss the recent advances in the field of protein kinase modulators, leverage molecular docking to model inhibitor-kinase interactions, and propose mechanisms of action that will aid in the design of next-generation protein kinase modulators (Part II).
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Affiliation(s)
- Shmuel Silnitsky
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Henrietta Szold St. 8, Safed 1311502, Israel; (S.S.); (M.Z.)
| | - Samuel J. S. Rubin
- Department of Medicine, School of Medicine, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA;
| | - Mulate Zerihun
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Henrietta Szold St. 8, Safed 1311502, Israel; (S.S.); (M.Z.)
| | - Nir Qvit
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Henrietta Szold St. 8, Safed 1311502, Israel; (S.S.); (M.Z.)
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2
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Colgan LA, Parra-Bueno P, Holman HL, Tu X, Jain A, Calubag MF, Misler JA, Gary C, Oz G, Suponitsky-Kroyter I, Okaz E, Yasuda R. Dual Regulation of Spine-Specific and Synapse-to-Nucleus Signaling by PKCδ during Plasticity. J Neurosci 2023; 43:5432-5447. [PMID: 37277178 PMCID: PMC10376934 DOI: 10.1523/jneurosci.0208-22.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 05/18/2023] [Accepted: 05/27/2023] [Indexed: 06/07/2023] Open
Abstract
The activity-dependent plasticity of synapses is believed to be the cellular basis of learning. These synaptic changes are mediated through the coordination of local biochemical reactions in synapses and changes in gene transcription in the nucleus to modulate neuronal circuits and behavior. The protein kinase C (PKC) family of isozymes has long been established as critical for synaptic plasticity. However, because of a lack of suitable isozyme-specific tools, the role of the novel subfamily of PKC isozymes is largely unknown. Here, through the development of fluorescence lifetime imaging-fluorescence resonance energy transfer activity sensors, we investigate novel PKC isozymes in synaptic plasticity in CA1 pyramidal neurons of mice of either sex. We find that PKCδ is activated downstream of TrkB and DAG production, and that the spatiotemporal nature of its activation depends on the plasticity stimulation. In response to single-spine plasticity, PKCδ is activated primarily in the stimulated spine and is required for local expression of plasticity. However, in response to multispine stimulation, a long-lasting and spreading activation of PKCδ scales with the number of spines stimulated and, by regulating cAMP response-element binding protein activity, couples spine plasticity to transcription in the nucleus. Thus, PKCδ plays a dual functional role in facilitating synaptic plasticity.SIGNIFICANCE STATEMENT Synaptic plasticity, or the ability to change the strength of the connections between neurons, underlies learning and memory and is critical for brain health. The protein kinase C (PKC) family is central to this process. However, understanding how these kinases work to mediate plasticity has been limited by a lack of tools to visualize and perturb their activity. Here, we introduce and use new tools to reveal a dual role for PKCδ in facilitating local synaptic plasticity and stabilizing this plasticity through spine-to-nucleus signaling to regulate transcription. This work provides new tools to overcome limitations in studying isozyme-specific PKC function and provides insight into molecular mechanisms of synaptic plasticity.
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Affiliation(s)
- Lesley A Colgan
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Paula Parra-Bueno
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Heather L Holman
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Xun Tu
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Anant Jain
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Mariah F Calubag
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Jaime A Misler
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Chancellor Gary
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Goksu Oz
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Irena Suponitsky-Kroyter
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Elwy Okaz
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Ryohei Yasuda
- Neuronal Signal Transduction, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
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3
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Crossay E, Jullian V, Trinel M, Sagnat D, Hamel D, Groppi E, Rolland C, Stigliani JL, Mejia K, Cabanillas BJ, Alric L, Buscail E, El Kalamouni C, Mavingui P, Deraison C, Racaud-Sultan C, Fabre N. Daphnanes diterpenes from the latex of Hura crepitans L. and their PKCζ-dependent anti-proliferative activity on colorectal cancer cells. Bioorg Med Chem 2023; 90:117366. [PMID: 37329676 DOI: 10.1016/j.bmc.2023.117366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/04/2023] [Accepted: 05/30/2023] [Indexed: 06/19/2023]
Abstract
Hura crepitans L. (Euphorbiaceae) is a thorn-covered tree widespread in South America, Africa and Asia which produces an irritating milky latex containing numerous secondary metabolites, notably daphnane-type diterpenes known as Protein Kinase C activators. Fractionation of a dichloromethane extract of the latex led to the isolation of five new daphnane diterpenes (1-5), along with two known analogs (6-7) including huratoxin. Huratoxin (6) and 4',5'-epoxyhuratoxin (4) were found to exhibit significant and selective cell growth inhibition against colorectal cancer cell line Caco-2 and primary colorectal cancer cells cultured as colonoids. The underlying mechanism of 4 and 6 was further investigated revealing the involvement of PKCζ in the cytostatic activity.
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Affiliation(s)
- Elise Crossay
- UMR 152 PharmaDev, Université de Toulouse, IRD, UPS, France
| | | | - Manon Trinel
- UMR 152 PharmaDev, Université de Toulouse, IRD, UPS, France
| | - David Sagnat
- IRSD, Université de Toulouse, INSERM, INRAE, ENVT, UPS, France; Toulouse Organoids Platform, Institut de Recherche en Santé Digestive, INSERM, Toulouse, France
| | - Dimitri Hamel
- IRSD, Université de Toulouse, INSERM, INRAE, ENVT, UPS, France; LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, France
| | - Emie Groppi
- UMR 152 PharmaDev, Université de Toulouse, IRD, UPS, France
| | - Corinne Rolland
- IRSD, Université de Toulouse, INSERM, INRAE, ENVT, UPS, France
| | | | - Kember Mejia
- Instituto de Investigaciones de la Amazonia Peruana (IIAP), Iquitos, Peru
| | - Billy Joel Cabanillas
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima 15102, Peru
| | - Laurent Alric
- Pole Digestif, Centre Hospitalier Universitaire, Toulouse, France
| | - Etienne Buscail
- IRSD, Université de Toulouse, INSERM, INRAE, ENVT, UPS, France; Département de Chirurgie Digestive, Unité de Chirurgie Colorectale, Centre Hospitalier Universitaire, Toulouse, France
| | - Chaker El Kalamouni
- UMR PIMIT, Université de La Réunion, INSERM U1187, CNRS 9192, IRD 249, La Réunion, France
| | - Patrick Mavingui
- UMR PIMIT, Université de La Réunion, INSERM U1187, CNRS 9192, IRD 249, La Réunion, France
| | - Céline Deraison
- IRSD, Université de Toulouse, INSERM, INRAE, ENVT, UPS, France
| | | | - Nicolas Fabre
- UMR 152 PharmaDev, Université de Toulouse, IRD, UPS, France.
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4
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Veuthey L, Aliotta A, Bertaggia Calderara D, Pereira Portela C, Alberio L. Mechanisms Underlying Dichotomous Procoagulant COAT Platelet Generation-A Conceptual Review Summarizing Current Knowledge. Int J Mol Sci 2022; 23:2536. [PMID: 35269679 PMCID: PMC8910683 DOI: 10.3390/ijms23052536] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/19/2022] [Accepted: 02/21/2022] [Indexed: 12/23/2022] Open
Abstract
Procoagulant platelets are a subtype of activated platelets that sustains thrombin generation in order to consolidate the clot and stop bleeding. This aspect of platelet activation is gaining more and more recognition and interest. In fact, next to aggregating platelets, procoagulant platelets are key regulators of thrombus formation. Imbalance of both subpopulations can lead to undesired thrombotic or bleeding events. COAT platelets derive from a common pro-aggregatory phenotype in cells capable of accumulating enough cytosolic calcium to trigger specific pathways that mediate the loss of their aggregating properties and the development of new adhesive and procoagulant characteristics. Complex cascades of signaling events are involved and this may explain why an inter-individual variability exists in procoagulant potential. Nowadays, we know the key agonists and mediators underlying the generation of a procoagulant platelet response. However, we still lack insight into the actual mechanisms controlling this dichotomous pattern (i.e., procoagulant versus aggregating phenotype). In this review, we describe the phenotypic characteristics of procoagulant COAT platelets, we detail the current knowledge on the mechanisms of the procoagulant response, and discuss possible drivers of this dichotomous diversification, in particular addressing the impact of the platelet environment during in vivo thrombus formation.
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Affiliation(s)
| | | | | | | | - Lorenzo Alberio
- Hemostasis and Platelet Research Laboratory, Division of Hematology and Central Hematology Laboratory, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), CH-1010 Lausanne, Switzerland; (L.V.); (A.A.); (D.B.C.); (C.P.P.)
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5
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Gu SH, Chen CH, Lin PL. Protein kinase C signalling involved in prothoracicotropic hormone-stimulated prothoracic glands in the silkworm, Bombyx mori. INSECT MOLECULAR BIOLOGY 2022; 31:115-126. [PMID: 34709697 DOI: 10.1111/imb.12744] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/27/2021] [Accepted: 10/20/2021] [Indexed: 06/13/2023]
Abstract
In the present study, the participation of protein kinase C (PKC) signalling in prothoracicotropic hormone (PTTH)-stimulated ecdysteroidogenesis in Bombyx prothoracic glands (PGs) is demonstrated and characterized. PTTH stimulated phosphorylation of a 37-kDa protein in Bombyx PGs both in vitro and in vivo, as recognized by a PKC substrate antibody. Treatment with either A23187 or thapsigargin also stimulated this 37-kDa protein phosphorylation. PTTH-stimulated phosphorylation of the 37-kDa protein was markedly attenuated in the absence of Ca2+ . The phospholipase C (PLC) inhibitor, U73122, greatly inhibited PTTH-stimulated phosphorylation of this protein, indicating the involvement of Ca2+ and PLC. A mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor (U0126), a phosphoinositide 3-kinase (PI3K) inhibitor (LY294002) and a chemical activator of adenosine 5'-monophosphate-activated protein kinase (AMPK) (5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside) did not affect PTTH-stimulated phosphorylation of the 37-kDa protein, implying that ERK and PI3K/AMPK are not the upstream signalling pathways for PKC-dependent protein phosphorylation. The mitochondrial oxidative phosphorylation inhibitors (the uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone and diphenylene iodonium) inhibited PTTH-stimulated phosphorylation of the 37-kDa protein, indicating its redox regulation. Treatment with PKC inhibitors (either calphostin C, chelerythrine C or rottlerin) reduced PTTH-stimulated phosphorylation of the 37-kDa protein. PTTH-stimulated ecdysteroidogenesis was also inhibited by treatment with rottlerin, thus further confirming participation of PKC-dependent phosphorylation in PTTH signalling. From these results, we demonstrated that redox-regulated PTTH-stimulated PKC signalling is involved in ecdysteroid secretion in Bombyx PGs.
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Affiliation(s)
- S-H Gu
- Department of Biology, National Museum of Natural Science, Taichung, Taiwan
| | - C-H Chen
- Chung Hwa University of Medical Technology, Tainan, Taiwan
| | - P-L Lin
- Department of Biology, National Museum of Natural Science, Taichung, Taiwan
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6
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Limaye AJ, Bendzunas GN, Kennedy EJ. Targeted disruption of PKC from AKAP signaling complexes. RSC Chem Biol 2021; 2:1227-1231. [PMID: 34458835 PMCID: PMC8341804 DOI: 10.1039/d1cb00106j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/16/2021] [Indexed: 12/13/2022] Open
Abstract
Protein Kinase C (PKC) is a member of the AGC subfamily of kinases and regulates a wide array of signaling pathways and physiological processes. Protein-protein interactions involving PKC and its scaffolding partners dictate the spatiotemporal dynamics of PKC activity, including its access to activating second messenger molecules and potential substrates. While the A Kinase Anchoring Protein (AKAP) family of scaffold proteins universally bind PKA, several were also found to scaffold PKC, thereby serving to tune its catalytic output. Targeting these scaffolding interactions can further shed light on the effect of subcellular compartmentalization on PKC signaling. Here we report the development of two hydrocarbon stapled peptides, CSTAD5 and CSTAD6, that are cell permeable and bind PKC to disrupt PKC-gravin complex formation in cells. Both constrained peptides downregulate PMA-induced cytoskeletal remodeling that is mediated by the PKC-gravin complex as measured by cell rounding. Further, these peptides downregulate PKC substrate phosphorylation and cell motility. To the best of our knowledge, no PKC-selective AKAP disruptors have previously been reported and thus CSTAD5 and CSTAD6 are novel disruptors of PKC scaffolding by AKAPs and may serve as powerful tools for dissecting AKAP-localized PKC signaling.
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Affiliation(s)
- Ameya J Limaye
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia Athens GA 30602 USA
| | - George N Bendzunas
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia Athens GA 30602 USA
| | - Eileen J Kennedy
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia Athens GA 30602 USA
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7
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Gao S, Zhao X, Hou L, Ma R, Zhou J, Zhu MX, Pan SJ, Li Y. The interplay between SUMOylation and phosphorylation of PKCδ facilitates oxidative stress-induced apoptosis. FEBS J 2021; 288:6447-6464. [PMID: 34089566 DOI: 10.1111/febs.16050] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 04/30/2021] [Accepted: 06/03/2021] [Indexed: 12/01/2022]
Abstract
Although the increase in the number of identified posttranslational modifications (PTMs) has substantially improved our knowledge about substrate site specificity of single PTMs, the fact that different types of PTMs can crosstalk and act in concert to exert important regulatory mechanisms for protein function has not gained much attention. Here, we show that protein kinase Cδ (PKCδ) is SUMOylated at lysine 473 in its C-terminal catalytic domain, and the SUMOylation increases PKCδ stability by repressing its ubiquitination. In addition, we uncover a functional interplay between the phosphorylation and SUMOylation of PKCδ, which can strengthen each other through recruiting SUMO E2/E3 ligases and the PKCδ kinase, respectively, to the PKCδ complexes. We identified PIAS2β as the SUMO E3 ligase of PKCδ. More importantly, by enhancing PKCδ protein stability and its phosphorylation through an interdependent interplay of the PTMs, the SUMOylation of PKCδ promotes apoptotic cell death induced by H2 O2 . We conclude that SUMOylation represents an important regulatory mechanism of PKCδ PTMs for the kinase's function in oxidative cell damage.
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Affiliation(s)
- Siman Gao
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, China
| | - Xiangteng Zhao
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, China
| | - Lin Hou
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, China
| | - Ruining Ma
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, China
| | - Jie Zhou
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, China
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, TX, USA
| | - Si-Jian Pan
- Department of Neurosurgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, China
| | - Yong Li
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, China
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8
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Mukherjee A, Roy S, Patidar A, Bodhale N, Dandapat J, Saha B, Sarkar A. TLR2 dimer-specific ligands selectively activate protein kinase C isoforms in Leishmania infection. Immunology 2021; 164:318-331. [PMID: 34021910 DOI: 10.1111/imm.13373] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 04/18/2021] [Accepted: 05/10/2021] [Indexed: 11/30/2022] Open
Abstract
Of the thirteen Toll-like receptors (TLRs) in mice, TLR2 has a unique ability of forming heterodimers with TLR1 and TLR6. Such associations lead to selective cellular signalling and cellular responses such as cytokine expression. One of the signalling intermediates is protein kinase C (PKC); of which, eight isoforms are expressed in macrophages. Leishmania-a protozoan parasite that resides and replicates in macrophages-selectively modulates PKC-α, PKC-β, PKC-δ and PKC-ζ isoforms in macrophages. As TLR2 plays significant roles in Leishmania infection, we examined whether these PKC isoforms play selective roles in TLR2 signalling and TLR2-induced anti-leishmanial functions. We observed that the TLR2 ligands-Pam3 CSK4 (TLR1/2), PGN (TLR2/2) and FSL (TLR2/6)-differentially phosphorylated and translocated PKC-α, PKC-β, PKC-δ and PKC-ζ isoforms to cell membrane in uninfected and L. major-infected macrophages. The PKC isoform-specific inhibitors differentially altered IL-10 and IL-12 expression, Th1 and Th2 responses and anti-leishmanial effects in macrophages and in BALB/c mice. While PKC isoforms' inhibitors had insignificant effects on the Pam3CSK4-induced anti-leishmanial functions, PGN-induced pro-leishmanial effects were enhanced by PKC-(α + β) inhibitors, whereas PKC-(δ + ζ) inhibitors enhanced the anti-leishmanial effects of FSL. These results indicated that the ligand-induced TLR2 dimerization triggered differential dose-dependent and kinetic profiles of PKC isoform activation and that selective targeting of PKC isoforms using their respective inhibitors in combination significantly modulated TLR2-induced anti-leishmanial functions. To the best of our knowledge, this is the first demonstration of TLR2 dimer signalling through PKC isoforms and TLR2-induced PKC isoform-targeted anti-leishmanial therapy.
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Affiliation(s)
| | - Sayoni Roy
- National Centre for Cell Science [NCCS], Pune, India
| | - Ashok Patidar
- National Centre for Cell Science [NCCS], Pune, India
| | - Neelam Bodhale
- National Centre for Cell Science [NCCS], Pune, India.,JBNSTS, Calcutta, India
| | | | - Bhaskar Saha
- Trident Academy of Creative Technology [TACT], Bhubaneswar, India.,National Centre for Cell Science [NCCS], Pune, India
| | - Arup Sarkar
- Trident Academy of Creative Technology [TACT], Bhubaneswar, India
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9
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Mai QN, Shenoy P, Quach T, Retamal JS, Gondin AB, Yeatman HR, Aurelio L, Conner JW, Poole DP, Canals M, Nowell CJ, Graham B, Davis TP, Briddon SJ, Hill SJ, Porter CJH, Bunnett NW, Halls ML, Veldhuis NA. A lipid-anchored neurokinin 1 receptor antagonist prolongs pain relief by a three-pronged mechanism of action targeting the receptor at the plasma membrane and in endosomes. J Biol Chem 2021; 296:100345. [PMID: 33515548 PMCID: PMC7949131 DOI: 10.1016/j.jbc.2021.100345] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 01/20/2021] [Accepted: 01/25/2021] [Indexed: 12/13/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) are traditionally known for signaling at the plasma membrane, but they can also signal from endosomes after internalization to control important pathophysiological processes. In spinal neurons, sustained endosomal signaling of the neurokinin 1 receptor (NK1R) mediates nociception, as demonstrated in models of acute and neuropathic pain. An NK1R antagonist, Spantide I (Span), conjugated to cholestanol (Span-Chol), accumulates in endosomes, inhibits endosomal NK1R signaling, and causes prolonged antinociception. However, the extent to which the Chol-anchor influences long-term location and activity is poorly understood. Herein, we used fluorescent correlation spectroscopy and targeted biosensors to characterize Span-Chol over time. The Chol-anchor increased local concentration of probe at the plasma membrane. Over time we observed an increase in NK1R-binding affinity and more potent inhibition of NK1R-mediated calcium signaling. Span-Chol, but not Span, caused a persistent decrease in NK1R recruitment of β-arrestin and receptor internalization to early endosomes. Using targeted biosensors, we mapped the relative inhibition of NK1R signaling as the receptor moved into the cell. Span selectively inhibited cell surface signaling, whereas Span-Chol partitioned into endosomal membranes and blocked endosomal signaling. In a preclinical model of pain, Span-Chol caused prolonged antinociception (>9 h), which is attributable to a three-pronged mechanism of action: increased local concentration at membranes, a prolonged decrease in NK1R endocytosis, and persistent inhibition of signaling from endosomes. Identifying the mechanisms that contribute to the increased preclinical efficacy of lipid-anchored NK1R antagonists is an important step toward understanding how we can effectively target intracellular GPCRs in disease.
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Affiliation(s)
- Quynh N Mai
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Drug Delivery, Disposition and Dynamics Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Medicinal Chemistry Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Priyank Shenoy
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Tim Quach
- Drug Delivery, Disposition and Dynamics Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Jeffri S Retamal
- Drug Delivery, Disposition and Dynamics Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Arisbel B Gondin
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Holly R Yeatman
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Luigi Aurelio
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Medicinal Chemistry Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Joshua W Conner
- Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Medicinal Chemistry Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Daniel P Poole
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Meritxell Canals
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, The University of Nottingham Medical School, Nottingham, UK; Centre of Membrane Proteins and Receptors, Universities of Birmingham and Nottingham, the Midlands, UK
| | - Cameron J Nowell
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Bim Graham
- Medicinal Chemistry Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Thomas P Davis
- Drug Delivery, Disposition and Dynamics Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane, Queensland, Australia
| | - Stephen J Briddon
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, The University of Nottingham Medical School, Nottingham, UK; Centre of Membrane Proteins and Receptors, Universities of Birmingham and Nottingham, the Midlands, UK
| | - Stephen J Hill
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, The University of Nottingham Medical School, Nottingham, UK; Centre of Membrane Proteins and Receptors, Universities of Birmingham and Nottingham, the Midlands, UK
| | - Christopher J H Porter
- Drug Delivery, Disposition and Dynamics Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Nigel W Bunnett
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Department of Pharmacology and Therapeutics, The University of Melbourne, Parkville, Victoria, Australia; Department of Molecular Pathobiology, New York University College of Dentistry, New York, New York, USA.
| | - Michelle L Halls
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia.
| | - Nicholas A Veldhuis
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Drug Delivery, Disposition and Dynamics Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia.
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10
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Ito S, Yokoyama U, Nakakoji T, Cooley MA, Sasaki T, Hatano S, Kato Y, Saito J, Nicho N, Iwasaki S, Umemura M, Fujita T, Masuda M, Asou T, Ishikawa Y. Fibulin-1 Integrates Subendothelial Extracellular Matrices and Contributes to Anatomical Closure of the Ductus Arteriosus. Arterioscler Thromb Vasc Biol 2020; 40:2212-2226. [PMID: 32640908 PMCID: PMC7447190 DOI: 10.1161/atvbaha.120.314729] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE The ductus arteriosus (DA) is a fetal artery connecting the aorta and pulmonary arteries. Progressive matrix remodeling, that is, intimal thickening (IT), occurs in the subendothelial region of DA to bring anatomic DA closure. IT is comprised of multiple ECMs (extracellular matrices) and migrated smooth muscle cells (SMCs). Because glycoprotein fibulin-1 binds to multiple ECMs and regulates morphogenesis during development, we investigated the role of fibulin-1 in DA closure. Approach and Results: Fibulin-1-deficient (Fbln1-/-) mice exhibited patent DA with hypoplastic IT. An unbiased transcriptome analysis revealed that EP4 (prostaglandin E receptor 4) stimulation markedly increased fibulin-1 in DA-SMCs via phospholipase C-NFκB (nuclear factor κB) signaling pathways. Fluorescence-activated cell sorting (FACS) analysis demonstrated that fibulin-1 binding protein versican was derived from DA-endothelial cells (ECs). We examined the effect of fibulin-1 on directional migration toward ECs in association with versican by using cocultured DA-SMCs and ECs. EP4 stimulation promoted directional DA-SMC migration toward ECs, which was attenuated by either silencing fibulin-1 or versican. Immunofluorescence demonstrated that fibulin-1 and versican V0/V1 were coexpressed at the IT of wild-type DA, whereas 30% of versican-deleted mice lacking a hyaluronan binding site displayed patent DA. Fibulin-1 expression was attenuated in the EP4-deficient mouse (Ptger4-/-) DA, which exhibits patent DA with hypoplastic IT, and fibulin-1 protein administration restored IT formation. In human DA, fibulin-1 and versican were abundantly expressed in SMCs and ECs, respectively. CONCLUSIONS Fibulin-1 contributes to DA closure by forming an environment favoring directional SMC migration toward the subendothelial region, at least, in part, in combination with EC-derived versican and its binding partner hyaluronan.
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Affiliation(s)
- Satoko Ito
- From the Cardiovascular Research Institute (S.I., U.Y., T.N., J.S., N.N., M.U., T.F., Y.I.), Yokohama City University, Japan.,Department of Physiology, Tokyo Medical University, Japan (S.I., U.Y., Y.K., J.S.)
| | - Utako Yokoyama
- From the Cardiovascular Research Institute (S.I., U.Y., T.N., J.S., N.N., M.U., T.F., Y.I.), Yokohama City University, Japan.,Department of Physiology, Tokyo Medical University, Japan (S.I., U.Y., Y.K., J.S.)
| | - Taichi Nakakoji
- From the Cardiovascular Research Institute (S.I., U.Y., T.N., J.S., N.N., M.U., T.F., Y.I.), Yokohama City University, Japan
| | - Marion A Cooley
- Department of Oral Biology and Diagnostic Sciences, Augusta University, GA (M.A.C.)
| | - Takako Sasaki
- Department of Biochemistry II, Oita University, Japan (T.S.)
| | - Sonoko Hatano
- Institute for Molecular Science of Medicine, Aichi Medical University, Japan (S.H.)
| | - Yuko Kato
- Department of Physiology, Tokyo Medical University, Japan (S.I., U.Y., Y.K., J.S.)
| | - Junichi Saito
- From the Cardiovascular Research Institute (S.I., U.Y., T.N., J.S., N.N., M.U., T.F., Y.I.), Yokohama City University, Japan.,Department of Physiology, Tokyo Medical University, Japan (S.I., U.Y., Y.K., J.S.)
| | - Naoki Nicho
- From the Cardiovascular Research Institute (S.I., U.Y., T.N., J.S., N.N., M.U., T.F., Y.I.), Yokohama City University, Japan
| | - Shiho Iwasaki
- Department of Pediatrics (S.I.), Yokohama City University, Japan
| | - Masanari Umemura
- From the Cardiovascular Research Institute (S.I., U.Y., T.N., J.S., N.N., M.U., T.F., Y.I.), Yokohama City University, Japan
| | - Takayuki Fujita
- From the Cardiovascular Research Institute (S.I., U.Y., T.N., J.S., N.N., M.U., T.F., Y.I.), Yokohama City University, Japan
| | - Munetaka Masuda
- Department of Surgery (M.M.), Yokohama City University, Japan
| | - Toshihide Asou
- Department of Cardiovascular Surgery, Kanagawa Children's Medical Center, Yokohama, Japan (T.A.)
| | - Yoshihiro Ishikawa
- From the Cardiovascular Research Institute (S.I., U.Y., T.N., J.S., N.N., M.U., T.F., Y.I.), Yokohama City University, Japan
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11
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Wright WS, Eshaq RS, Lee M, Kaur G, Harris NR. Retinal Physiology and Circulation: Effect of Diabetes. Compr Physiol 2020; 10:933-974. [PMID: 32941691 PMCID: PMC10088460 DOI: 10.1002/cphy.c190021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In this article, we present a discussion of diabetes and its complications, including the macrovascular and microvascular effects, with the latter of consequence to the retina. We will discuss the anatomy and physiology of the retina, including aspects of metabolism and mechanisms of oxygenation, with the latter accomplished via a combination of the retinal and choroidal blood circulations. Both of these vasculatures are altered in diabetes, with the retinal circulation intimately involved in the pathology of diabetic retinopathy. The later stages of diabetic retinopathy involve poorly controlled angiogenesis that is of great concern, but in our discussion, we will focus more on several alterations in the retinal circulation occurring earlier in the progression of disease, including reductions in blood flow and a possible redistribution of perfusion that may leave some areas of the retina ischemic and hypoxic. Finally, we include in this article a more recent area of investigation regarding the diabetic retinal vasculature, that is, the alterations to the endothelial surface layer that normally plays a vital role in maintaining physiological functions. © 2020 American Physiological Society. Compr Physiol 10:933-974, 2020.
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Affiliation(s)
- William S Wright
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, South Carolina, USA
| | - Randa S Eshaq
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Minsup Lee
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Gaganpreet Kaur
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Norman R Harris
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
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12
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Gu SH, Chen CH, Hsieh HY, Lin PL. Expression of protein kinase C in relation to the embryonic diapause process in the silkworm, Bombyx mori. JOURNAL OF INSECT PHYSIOLOGY 2020; 121:104010. [PMID: 31917243 DOI: 10.1016/j.jinsphys.2019.104010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 12/28/2019] [Accepted: 12/30/2019] [Indexed: 06/10/2023]
Abstract
In the present study, we investigated the expression of protein kinase C (PKC) signaling during the embryonic diapause process of Bombyx mori. PKC activity, determined using an antibody to phosphorylated substrates of PKC, was found to be significantly higher in developing eggs as compared to that of diapause eggs. In eggs whose diapause initiation was prevented by HCl, non-diapause eggs, and eggs in which diapause had been terminated by chilling of diapausing eggs at 5 °C for 70 days and then were transferred to 25 °C, PKC-dependent phosphorylation levels of multiple proteins showed dramatic stage-dependent increases compared to those of diapause eggs. Higher protein levels of PKC were also detected in developing eggs as compared to those of diapause eggs. Determination of PKC enzymatic activity during the middle embryonic stage showed higher PKC activity in developing eggs compared to diapause eggs, thus further confirming differential regulation of PKC signaling during the embryonic diapause process. Examination of temporal changes in mRNA expression levels of classical PKC (cPKC) and atypical PKC (aPKC) showed no difference between diapause and HCl-treated eggs. These results demonstrated that differential expressions of PKC signaling between diapause and developing eggs are related to the embryonic diapause process of B. mori.
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Affiliation(s)
- Shi-Hong Gu
- Department of Biology, National Museum of Natural Science, 1 Kuan-Chien Road, Taichung 404, Taiwan, ROC.
| | - Chien-Hung Chen
- Chung Hwa University of Medical Technology, 89 Wen-Hwa 1st Road, Jen-Te Township, Tainan County 717, Taiwan, ROC
| | - Hsiao-Yen Hsieh
- Department of Biology, National Museum of Natural Science, 1 Kuan-Chien Road, Taichung 404, Taiwan, ROC
| | - Pei-Ling Lin
- Department of Biology, National Museum of Natural Science, 1 Kuan-Chien Road, Taichung 404, Taiwan, ROC
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13
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Ravichandran VS, Patel HJ, Pagani FD, Westfall MV. Cardiac contractile dysfunction and protein kinase C-mediated myofilament phosphorylation in disease and aging. J Gen Physiol 2019; 151:1070-1080. [PMID: 31366607 PMCID: PMC6719401 DOI: 10.1085/jgp.201912353] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 05/25/2019] [Accepted: 06/19/2019] [Indexed: 01/10/2023] Open
Abstract
Increases in protein kinase C (PKC) are associated with diminished cardiac function, but the contribution of downstream myofilament phosphorylation is debated in human and animal models of heart failure. The current experiments evaluated PKC isoform expression, downstream cardiac troponin I (cTnI) S44 phosphorylation (p-S44), and contractile function in failing (F) human myocardium, and in rat models of cardiac dysfunction caused by pressure overload and aging. In F human myocardium, elevated PKCα expression and cTnI p-S44 developed before ventricular assist device implantation. Circulatory support partially reduced PKCα expression and cTnI p-S44 levels and improved cellular contractile function. Gene transfer of dominant negative PKCα (PKCαDN) into F human myocytes also improved contractile function and reduced cTnI p-S44. Heightened cTnI phosphorylation of the analogous residue accompanied reduced myocyte contractile function in a rat model of pressure overload and in aged Fischer 344 × Brown Norway F1 rats (≥26 mo). Together, these results indicate PKC-targeted cTnI p-S44 accompanies cardiac cellular dysfunction in human and animal models. Interfering with PKCα activity reduces downstream cTnI p-S44 levels and partially restores function, suggesting cTnI p-S44 may be a useful target to improve contractile function in the future.
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Affiliation(s)
- Vani S Ravichandran
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI
- Department of Cardiac Surgery, University of Michigan, Ann Arbor, MI
| | - Himanshu J Patel
- Department of Cardiac Surgery, University of Michigan, Ann Arbor, MI
| | - Francis D Pagani
- Department of Cardiac Surgery, University of Michigan, Ann Arbor, MI
| | - Margaret V Westfall
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI
- Department of Cardiac Surgery, University of Michigan, Ann Arbor, MI
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14
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Liu Z, Khalil RA. Evolving mechanisms of vascular smooth muscle contraction highlight key targets in vascular disease. Biochem Pharmacol 2018; 153:91-122. [PMID: 29452094 PMCID: PMC5959760 DOI: 10.1016/j.bcp.2018.02.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 02/12/2018] [Indexed: 12/11/2022]
Abstract
Vascular smooth muscle (VSM) plays an important role in the regulation of vascular function. Identifying the mechanisms of VSM contraction has been a major research goal in order to determine the causes of vascular dysfunction and exaggerated vasoconstriction in vascular disease. Major discoveries over several decades have helped to better understand the mechanisms of VSM contraction. Ca2+ has been established as a major regulator of VSM contraction, and its sources, cytosolic levels, homeostatic mechanisms and subcellular distribution have been defined. Biochemical studies have also suggested that stimulation of Gq protein-coupled membrane receptors activates phospholipase C and promotes the hydrolysis of membrane phospholipids into inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). IP3 stimulates initial Ca2+ release from the sarcoplasmic reticulum, and is buttressed by Ca2+ influx through voltage-dependent, receptor-operated, transient receptor potential and store-operated channels. In order to prevent large increases in cytosolic Ca2+ concentration ([Ca2+]c), Ca2+ removal mechanisms promote Ca2+ extrusion via the plasmalemmal Ca2+ pump and Na+/Ca2+ exchanger, and Ca2+ uptake by the sarcoplasmic reticulum and mitochondria, and the coordinated activities of these Ca2+ handling mechanisms help to create subplasmalemmal Ca2+ domains. Threshold increases in [Ca2+]c form a Ca2+-calmodulin complex, which activates myosin light chain (MLC) kinase, and causes MLC phosphorylation, actin-myosin interaction, and VSM contraction. Dissociations in the relationships between [Ca2+]c, MLC phosphorylation, and force have suggested additional Ca2+ sensitization mechanisms. DAG activates protein kinase C (PKC) isoforms, which directly or indirectly via mitogen-activated protein kinase phosphorylate the actin-binding proteins calponin and caldesmon and thereby enhance the myofilaments force sensitivity to Ca2+. PKC-mediated phosphorylation of PKC-potentiated phosphatase inhibitor protein-17 (CPI-17), and RhoA-mediated activation of Rho-kinase (ROCK) inhibit MLC phosphatase and in turn increase MLC phosphorylation and VSM contraction. Abnormalities in the Ca2+ handling mechanisms and PKC and ROCK activity have been associated with vascular dysfunction in multiple vascular disorders. Modulators of [Ca2+]c, PKC and ROCK activity could be useful in mitigating the increased vasoconstriction associated with vascular disease.
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Affiliation(s)
- Zhongwei Liu
- Vascular Surgery Research Laboratories, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA
| | - Raouf A Khalil
- Vascular Surgery Research Laboratories, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA.
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15
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Eshaq RS, Aldalati AMZ, Alexander JS, Harris NR. Diabetic retinopathy: Breaking the barrier. PATHOPHYSIOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY FOR PATHOPHYSIOLOGY 2017; 24:229-241. [PMID: 28732591 PMCID: PMC5711541 DOI: 10.1016/j.pathophys.2017.07.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 06/26/2017] [Accepted: 07/04/2017] [Indexed: 12/28/2022]
Abstract
Diabetic retinopathy (DR) remains a major complication of diabetes and a leading cause of blindness among adults worldwide. DR is a progressive disease affecting both type I and type II diabetic patients at any stage of the disease, and targets the retinal microvasculature. DR results from multiple biochemical, molecular and pathophysiological changes to the retinal vasculature, which affect both microcirculatory functions and ultimately photoreceptor function. Several neural, endothelial, and support cell (e.g., pericyte) mechanisms are altered in a pathological fashion in the hyperglycemic environment during diabetes that can disturb important cell surface components in the vasculature producing the features of progressive DR pathophysiology. These include loss of the glycocalyx, blood-retinal barrier dysfunction, increased expression of inflammatory cell markers and adhesion of blood leukocytes and platelets. Included in this review is a discussion of modifications that occur at or near the surface of the retinal vascular endothelial cells, and the consequences of these alterations on the integrity of the retina.
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Affiliation(s)
- Randa S Eshaq
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center -Shreveport, 1501 Kings Highway, Shreveport, LA 71130, United States
| | - Alaa M Z Aldalati
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center -Shreveport, 1501 Kings Highway, Shreveport, LA 71130, United States
| | - J Steven Alexander
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center -Shreveport, 1501 Kings Highway, Shreveport, LA 71130, United States
| | - Norman R Harris
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center -Shreveport, 1501 Kings Highway, Shreveport, LA 71130, United States.
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16
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Ringvold HC, Khalil RA. Protein Kinase C as Regulator of Vascular Smooth Muscle Function and Potential Target in Vascular Disorders. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 78:203-301. [PMID: 28212798 PMCID: PMC5319769 DOI: 10.1016/bs.apha.2016.06.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Vascular smooth muscle (VSM) plays an important role in maintaining vascular tone. In addition to Ca2+-dependent myosin light chain (MLC) phosphorylation, protein kinase C (PKC) is a major regulator of VSM function. PKC is a family of conventional Ca2+-dependent α, β, and γ, novel Ca2+-independent δ, ɛ, θ, and η, and atypical ξ, and ι/λ isoforms. Inactive PKC is mainly cytosolic, and upon activation it undergoes phosphorylation, maturation, and translocation to the surface membrane, the nucleus, endoplasmic reticulum, and other cell organelles; a process facilitated by scaffold proteins such as RACKs. Activated PKC phosphorylates different substrates including ion channels, pumps, and nuclear proteins. PKC also phosphorylates CPI-17 leading to inhibition of MLC phosphatase, increased MLC phosphorylation, and enhanced VSM contraction. PKC could also initiate a cascade of protein kinases leading to phosphorylation of the actin-binding proteins calponin and caldesmon, increased actin-myosin interaction, and VSM contraction. Increased PKC activity has been associated with vascular disorders including ischemia-reperfusion injury, coronary artery disease, hypertension, and diabetic vasculopathy. PKC inhibitors could test the role of PKC in different systems and could reduce PKC hyperactivity in vascular disorders. First-generation PKC inhibitors such as staurosporine and chelerythrine are not very specific. Isoform-specific PKC inhibitors such as ruboxistaurin have been tested in clinical trials. Target delivery of PKC pseudosubstrate inhibitory peptides and PKC siRNA may be useful in localized vascular disease. Further studies of PKC and its role in VSM should help design isoform-specific PKC modulators that are experimentally potent and clinically safe to target PKC in vascular disease.
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Affiliation(s)
- H C Ringvold
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - R A Khalil
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.
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