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Phillips S, Chatham JC, McMahon LL. Forskolin reverses the O-GlcNAcylation dependent decrease in GABA AR current amplitude at hippocampal synapses possibly at a neurosteroid site on GABA ARs. Sci Rep 2024; 14:17461. [PMID: 39075105 PMCID: PMC11286967 DOI: 10.1038/s41598-024-66025-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 06/26/2024] [Indexed: 07/31/2024] Open
Abstract
GABAergic transmission is influenced by post-translational modifications, like phosphorylation, impacting channel conductance, allosteric modulator sensitivity, and membrane trafficking. O-GlcNAcylation is a post-translational modification involving the O-linked attachment of β-N-acetylglucosamine on serine/threonine residues. Previously we reported an acute increase in O-GlcNAcylation elicits a long-term depression of evoked GABAAR inhibitory postsynaptic currents (eIPSCs) onto hippocampal principal cells. Importantly, O-GlcNAcylation and phosphorylation can co-occur or compete for the same residue; whether they interact in modulating GABAergic IPSCs is unknown. We tested this by recording IPSCs from hippocampal principal cells and pharmacologically increased O-GlcNAcylation, before or after increasing serine phosphorylation using the adenylate cyclase activator, forskolin. Although forskolin had no significant effect on baseline eIPSC amplitude, we found that a prior increase in O-GlcNAcylation unmasks a forskolin-dependent increase in eIPSC amplitude, reversing the O-GlcNAc-induced eIPSC depression. Inhibition of adenylate cyclase or protein kinase A did not prevent the potentiating effect of forskolin, indicating serine phosphorylation is not the mechanism. Surprisingly, increasing O-GlcNAcylation also unmasked a potentiating effect of the neurosteroids 5α-pregnane-3α,21-diol-20-one (THDOC) and progesterone on eIPSC amplitude in about half of the recorded cells, mimicking forskolin. Our findings show that under conditions of heightened O-GlcNAcylation, the neurosteroid site on synaptic GABAARs is possibly accessible to agonists, permitting strengthening of synaptic inhibition.
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Affiliation(s)
- Shekinah Phillips
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
- Department of Neuroscience, Medical University of South Carolina, 173 Ashley Ave, Charleston, SC, 29403, USA
| | - John C Chatham
- Division of Molecular and Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Lori L McMahon
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
- Department of Neuroscience, Medical University of South Carolina, 173 Ashley Ave, Charleston, SC, 29403, USA.
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Phillips S, Chatham JC, McMahon LL. Forskolin reverses the O-GlcNAcylation dependent decrease in GABAAR current amplitude at hippocampal synapses possibly at a neurosteroid site on GABAARs. RESEARCH SQUARE 2024:rs.3.rs-4140038. [PMID: 38659738 PMCID: PMC11042418 DOI: 10.21203/rs.3.rs-4140038/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
GABAergic transmission is influenced by post-translational modifications, like phosphorylation, impacting channel conductance, allosteric modulator sensitivity, and membrane trafficking. O-GlcNAcylation is a post-translational modification involving the O-linked attachment of β-N-acetylglucosamine on serine/threonine residues. Previously we reported an acute increase in O-GlcNAcylation elicits a long-term depression of evoked GABAAR inhibitory post synaptic currents (eIPSCs) onto hippocampal principal cells. Importantly, O-GlcNAcylation and phosphorylation can co-occur or compete for the same residue; whether they interact in modulating GABAergic IPSCs is unknown. We tested this by recording IPSCs from hippocampal principal cells and pharmacologically increased O-GlcNAcylation, before or after increasing serine phosphorylation using the adenylate cyclase activator, forskolin. Although forskolin had no significant effect on baseline eIPSC amplitude, we found that a prior increase in O-GlcNAcylation unmasks a forskolin-dependent increase in eIPSC amplitude, reversing the O-GlcNAc-induced eIPSC depression. Inhibition of adenylate cyclase or protein kinase A did not prevent the potentiating effect of forskolin, indicating serine phosphorylation is not the mechanism. Surprisingly, increasing O-GlcNAcylation also unmasked a potentiating effect of the neurosteroids 5α-pregnane-3α,21-diol-20-one (THDOC) and progesterone on eIPSC amplitude, mimicking forskolin. Our findings show under conditions of heightened O-GlcNAcylation, the neurosteroid site on synaptic GABAARs is accessible to agonists, permitting strengthening of synaptic inhibition.
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3
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Phillips S, Chatham JC, McMahon L. Forskolin reverses the O-GlcNAcylation dependent decrease in GABAAR current amplitude at hippocampal synapses possibly through a neurosteroid site on GABAARs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.06.583612. [PMID: 38496430 PMCID: PMC10942432 DOI: 10.1101/2024.03.06.583612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
GABAergic transmission is influenced by post-translational modifications, like phosphorylation, impacting channel conductance, allosteric modulator sensitivity, and membrane trafficking. O-GlcNAcylation is a post-translational modification involving the O-linked attachment of β-N-acetylglucosamine on serine/threonine residues. Previously we reported an acute increase in O-GlcNAcylation elicits a long-term depression of evoked GABAAR inhibitory post synaptic currents (eIPSCs) onto hippocampal principal cells. Importantly O-GlcNAcylation and phosphorylation can co-occur or compete for the same residue; whether they interact in modulating GABAergic IPSCs is unknown. We tested this by recording IPSCs from hippocampal principal cells and pharmacologically increased O-GlcNAcylation, before or after increasing serine phosphorylation using the adenylate cyclase activator, forskolin. Although forskolin had no significant effect on baseline eIPSC amplitude, we found that a prior increase in O-GlcNAcylation unmasks a forskolin-dependent increase in eIPSC amplitude, reversing the O-GlcNAc-induced eIPSC depression. Inhibition of adenylate cyclase or protein kinase A did not prevent the potentiating effect of forskolin, indicating serine phosphorylation is not the mechanism. Surprisingly, increasing O-GlcNAcylation also unmasked a potentiating effect of the neurosteroids 5α-pregnane-3α,21-diol-20-one (THDOC) and progesterone on eIPSC amplitude, mimicking forskolin. Our findings show under conditions of heightened O-GlcNAcylation, the neurosteroid site on synaptic GABAARs is accessible to agonists, permitting strengthening of synaptic inhibition.
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4
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Nguyen QTN, Park J, Kim DY, Tran DT, Han IO. Forskolin rescues hypoxia-induced cognitive dysfunction in zebrafish with potential involvement of O-GlcNAc cycling regulation. Biochem Pharmacol 2024; 221:116032. [PMID: 38281601 DOI: 10.1016/j.bcp.2024.116032] [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: 12/09/2023] [Revised: 12/28/2023] [Accepted: 01/23/2024] [Indexed: 01/30/2024]
Abstract
Repeated sublethal hypoxia exposure induces brain inflammation and affects the initiation and progression of cognitive dysfunction. Experiments from the current study showed that hypoxic exposure downregulates PKA/CREB signaling, which is restored by forskolin (FSK), an adenylate cyclase activator, in both Neuro2a (N2a) cells and zebrafish brain. FSK significantly protected N2a cells from hypoxia-induced cell death and neurite shrinkage. Intraperitoneal administration of FSK for 5 days on zebrafish additionally led to significant recovery from hypoxia-induced social interaction impairment and learning and memory (L/M) deficit. FSK suppressed hypoxia-induced neuroinflammation, as indicated by the observed decrease in NF-κB activation and GFAP expression. We further investigated the potential effect of FSK on O-GlcNAcylation changes induced by hypoxia. Intriguingly FSK induced marked upregulation of the protein level of O-GlcNAc transferase catalyzing addition of the GlcNAc group to target proteins, accompanied by elevated O-GlcNAcylation of nucleocytoplasmic proteins. The hypoxia-induced O-GlcNAcylation decrease in the brain of zebrafish was considerably restored following FSK treatment. Based on the collective results, we propose that FSK rescues hypoxia-induced cognitive dysfunction, potentially through regulation of HBP/O-GlcNAc cycling.
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Affiliation(s)
- Quynh T N Nguyen
- Department of Biomedical Science, Program in Biomedical Science and Engineering, College of Medicine, Inha University, Incheon, South Korea
| | - Jiwon Park
- Department of Biomedical Science, Program in Biomedical Science and Engineering, College of Medicine, Inha University, Incheon, South Korea
| | - Dong Yeol Kim
- Department of Biomedical Science, Program in Biomedical Science and Engineering, College of Medicine, Inha University, Incheon, South Korea
| | - Duong T Tran
- Department of Biomedical Science, Program in Biomedical Science and Engineering, College of Medicine, Inha University, Incheon, South Korea
| | - Inn Oc Han
- Department of Biomedical Science, Program in Biomedical Science and Engineering, College of Medicine, Inha University, Incheon, South Korea.
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Sarkar OS, Donninger H, Al Rayyan N, Chew LC, Stamp B, Zhang X, Whitt A, Li C, Hall M, Mitchell RA, Zippelius A, Eaton J, Chesney JA, Yaddanapudi K. Monocytic MDSCs exhibit superior immune suppression via adenosine and depletion of adenosine improves efficacy of immunotherapy. SCIENCE ADVANCES 2023; 9:eadg3736. [PMID: 37390211 PMCID: PMC10313166 DOI: 10.1126/sciadv.adg3736] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 05/26/2023] [Indexed: 07/02/2023]
Abstract
Immune checkpoint inhibitor (ICI) therapy is effective against many cancers for a subset of patients; a large percentage of patients remain unresponsive to this therapy. One contributing factor to ICI resistance is accumulation of monocytic myeloid-derived suppressor cells (M-MDSCs), a subset of innate immune cells with potent immunosuppressive activity against T lymphocytes. Here, using lung, melanoma, and breast cancer mouse models, we show that CD73-expressing M-MDSCs in the tumor microenvironment (TME) exhibit superior T cell suppressor function. Tumor-derived PGE2, a prostaglandin, directly induces CD73 expression in M-MDSCs via both Stat3 and CREB. The resulting CD73 overexpression induces elevated levels of adenosine, a nucleoside with T cell-suppressive activity, culminating in suppression of antitumor CD8+ T cell activity. Depletion of adenosine in the TME by the repurposed drug PEGylated adenosine deaminase (PEG-ADA) increases CD8+ T cell activity and enhances response to ICI therapy. Use of PEG-ADA can therefore be a therapeutic option to overcome resistance to ICIs in cancer patients.
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Affiliation(s)
- Omar S. Sarkar
- Department of Microbiology and Immunology, University of Louisville, Louisville, KY, USA
| | - Howard Donninger
- Department of Medicine, University of Louisville, Louisville, KY, USA
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA
- Experimental Therapeutics Program, University of Louisville, Louisville, KY, USA
| | - Numan Al Rayyan
- Department of Medicine, University of Louisville, Louisville, KY, USA
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA
- Natural Agricultural Research Center, P.O. Box 639, Baq'a 19381, Jordan
| | - Lewis C. Chew
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA
| | - Bryce Stamp
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA
| | - Xiang Zhang
- Department of Chemistry, University of Louisville, Louisville, KY, USA
| | - Aaron Whitt
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY, USA
| | - Chi Li
- Department of Medicine, University of Louisville, Louisville, KY, USA
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA
- Experimental Therapeutics Program, University of Louisville, Louisville, KY, USA
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY, USA
| | - Melissa Hall
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA
| | - Robert A. Mitchell
- Department of Microbiology and Immunology, University of Louisville, Louisville, KY, USA
- Department of Surgery, Division of Immunotherapy, University of Louisville, Louisville, KY, USA
- Immuno-Oncology Group, Brown Cancer Center, University of Louisville, Louisville, KY, USA
| | - Alfred Zippelius
- Center for Immunotherapy, Cancer Center Medical Oncology, University Hospital Basel, Switzerland
| | - John Eaton
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA
- Immuno-Oncology Group, Brown Cancer Center, University of Louisville, Louisville, KY, USA
| | - Jason A. Chesney
- Department of Medicine, University of Louisville, Louisville, KY, USA
- Department of Surgery, Division of Immunotherapy, University of Louisville, Louisville, KY, USA
- Immuno-Oncology Group, Brown Cancer Center, University of Louisville, Louisville, KY, USA
| | - Kavitha Yaddanapudi
- Department of Microbiology and Immunology, University of Louisville, Louisville, KY, USA
- Department of Surgery, Division of Immunotherapy, University of Louisville, Louisville, KY, USA
- Immuno-Oncology Group, Brown Cancer Center, University of Louisville, Louisville, KY, USA
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Bektik E, Sun Y, Dennis AT, Sakon P, Yang D, Deschênes I, Fu JD. Inhibition of CREB-CBP Signaling Improves Fibroblast Plasticity for Direct Cardiac Reprogramming. Cells 2021; 10:cells10071572. [PMID: 34206684 PMCID: PMC8307124 DOI: 10.3390/cells10071572] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/09/2021] [Accepted: 06/17/2021] [Indexed: 01/14/2023] Open
Abstract
Direct cardiac reprogramming of fibroblasts into induced cardiomyocytes (iCMs) is a promising approach but remains a challenge in heart regeneration. Efforts have focused on improving the efficiency by understanding fundamental mechanisms. One major challenge is that the plasticity of cultured fibroblast varies batch to batch with unknown mechanisms. Here, we noticed a portion of in vitro cultured fibroblasts have been activated to differentiate into myofibroblasts, marked by the expression of αSMA, even in primary cell cultures. Both forskolin, which increases cAMP levels, and TGFβ inhibitor SB431542 can efficiently suppress myofibroblast differentiation of cultured fibroblasts. However, SB431542 improved but forskolin blocked iCM reprogramming of fibroblasts that were infected with retroviruses of Gata4, Mef2c, and Tbx5 (GMT). Moreover, inhibitors of cAMP downstream signaling pathways, PKA or CREB-CBP, significantly improved the efficiency of reprogramming. Consistently, inhibition of p38/MAPK, another upstream regulator of CREB-CBP, also improved reprogramming efficiency. We then investigated if inhibition of these signaling pathways in primary cultured fibroblasts could improve their plasticity for reprogramming and found that preconditioning of cultured fibroblasts with CREB-CBP inhibitor significantly improved the cellular plasticity of fibroblasts to be reprogrammed, yielding ~2-fold more iCMs than untreated control cells. In conclusion, suppression of CREB-CBP signaling improves fibroblast plasticity for direct cardiac reprogramming.
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Affiliation(s)
- Emre Bektik
- Department of Physiology, Cell Biology College of Medicine, Ohio State University, 333 W 10th Avenue, Columbus, OH 43210, USA; (E.B.); (D.Y.); (I.D.)
- Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA;
| | - Yu Sun
- Heart and Vascular Research Center, Department of Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, OH 44109, USA; (Y.S.); (A.T.D.)
| | - Adrienne T. Dennis
- Heart and Vascular Research Center, Department of Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, OH 44109, USA; (Y.S.); (A.T.D.)
| | - Phraew Sakon
- Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA;
| | - Dandan Yang
- Department of Physiology, Cell Biology College of Medicine, Ohio State University, 333 W 10th Avenue, Columbus, OH 43210, USA; (E.B.); (D.Y.); (I.D.)
| | - Isabelle Deschênes
- Department of Physiology, Cell Biology College of Medicine, Ohio State University, 333 W 10th Avenue, Columbus, OH 43210, USA; (E.B.); (D.Y.); (I.D.)
- Heart and Vascular Research Center, Department of Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, OH 44109, USA; (Y.S.); (A.T.D.)
| | - Ji-Dong Fu
- Department of Physiology, Cell Biology College of Medicine, Ohio State University, 333 W 10th Avenue, Columbus, OH 43210, USA; (E.B.); (D.Y.); (I.D.)
- Heart and Vascular Research Center, Department of Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, OH 44109, USA; (Y.S.); (A.T.D.)
- Correspondence: ; Tel.: +1-(614)-685-0657
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Drown BS, Shirai T, Rack JGM, Ahel I, Hergenrother PJ. Monitoring Poly(ADP-ribosyl)glycohydrolase Activity with a Continuous Fluorescent Substrate. Cell Chem Biol 2018; 25:1562-1570.e19. [PMID: 30318463 PMCID: PMC6309520 DOI: 10.1016/j.chembiol.2018.09.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 07/17/2018] [Accepted: 09/12/2018] [Indexed: 11/30/2022]
Abstract
The post-translational modification (PTM) and signaling molecule poly(ADP-ribose) (PAR) has an impact on diverse biological processes. This PTM is regulated by a series of ADP-ribosyl glycohydrolases (PARG enzymes) that cleave polymers and/or liberate monomers from their protein targets. Existing methods for monitoring these hydrolases rely on detection of the natural substrate, PAR, commonly achieved via radioisotopic labeling. Here we disclose a general substrate for monitoring PARG activity, TFMU-ADPr, which directly reports on total PAR hydrolase activity via release of a fluorophore; this substrate has excellent reactivity, generality (processed by the major PARG enzymes), stability, and usability. A second substrate, TFMU-IDPr, selectively reports on PARG activity only from the enzyme ARH3. Use of these probes in whole-cell lysate experiments has revealed a mechanism by which ARH3 is inhibited by cholera toxin. TFMU-ADPr and TFMU-IDPr are versatile tools for assessing small-molecule inhibitors in vitro and probing the regulation of ADP-ribosyl catabolic enzymes.
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Affiliation(s)
- Bryon S Drown
- Department of Chemistry and Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 261 Roger Adams Lab Box 36-5, 600 S. Mathews Avenue, Urbana, IL 61801, USA
| | - Tomohiro Shirai
- Department of Chemistry and Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 261 Roger Adams Lab Box 36-5, 600 S. Mathews Avenue, Urbana, IL 61801, USA
| | | | - Ivan Ahel
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Paul J Hergenrother
- Department of Chemistry and Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 261 Roger Adams Lab Box 36-5, 600 S. Mathews Avenue, Urbana, IL 61801, USA.
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Abstract
One of the most important public health problems in the world today is the emergence and dissemination of drug-resistant malaria parasites. Plasmodium falciparum is the causative agent of the most lethal form of human malaria. New anti-malarial strategies are urgently required, and their design and development require the identification of potential therapeutic targets. However, the molecular mechanisms controlling the life cycle of the malaria parasite are still poorly understood. The published genome sequence of P. falciparum and previous studies have revealed that several homologues of eukaryotic signalling proteins, such as protein kinases, are relatively conserved. Protein kinases are now widely recognized as important drug targets in protozoan parasites. Cyclic AMP-dependent protein kinase (PKA) is implicated in numerous processes in mammalian cells, and the regulatory mechanisms of the cAMP pathway have been characterized. P. falciparum cAMP-dependent protein kinase plays an important role in the parasite's life cycle and thus represents an attractive target for the development of anti-malarial drugs. In this review, we focus on the P. falciparum cAMP/PKA pathway to provide new insights and an improved understanding of this signalling cascade.
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Yamaoka J, Imamura S. Analysis of mechanisms of epidermal proliferation induced by intracutaneous injection of cholera toxin by the use of site-specifically mutated cholera toxins. J Dermatol Sci 1998; 16:182-90. [PMID: 9651815 DOI: 10.1016/s0923-1811(97)00050-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Intracutaneous injection of cholera toxin (CT) into rabbits increases vascular permeability and induces epidermal proliferation. To understand the mechanisms of these effects on the skin, we evaluated the involvement of the ADP-ribosyltransferase activity of the A subunit of CT and receptor-binding interactions between GM1-ganglioside and the B subunit of CT. We constructed two mutant CTs, E112K and W88K, by site-directed mutagenesis. Mutant CT-E112K, in which glutamic acid at position 112 (E112) of the A subunit of CT was replaced by lysine, has been shown to have lost its biological activity on Chinese hamster ovary (CHO) cells because of its abolished ADP-ribosyltransferase activity. Mutant CT-W88K, in which tryptophan at position 88 (W88) of the B subunit of CT was replaced by lysine, has been shown to have lost its binding ability to GM1-ganglioside. Intracutaneous injection of these mutant CTs evoked less vascular permeability and less epidermal proliferation than recombinant wild-type CT. These results suggest that: (1) the ADP-ribosyltransferase activity carried by E112 of the A subunit of CT; and (2) the binding ability to GM1-ganglioside via W88 of the B subunit of CT are essential for these effects of CT on the skin.
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Affiliation(s)
- J Yamaoka
- Department of Dermatology, Kyoto University Hospital, Japan
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10
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Roger PP, Reuse S, Maenhaut C, Dumont JE. Multiple facets of the modulation of growth by cAMP. VITAMINS AND HORMONES 1995; 51:59-191. [PMID: 7483330 DOI: 10.1016/s0083-6729(08)61038-9] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- P P Roger
- Institute of Interdisciplinary Research, Free University of Brussels, Belgium
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11
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Matsuo S, Iizuka H. Cholera toxin- and forskolin-induced cyclic AMP accumulations of pig skin (epidermis). Modulation by chemicals which reveal the beta-adrenergic augmentation effect. J Dermatol Sci 1990; 1:7-13. [PMID: 1706621 DOI: 10.1016/0923-1811(90)90004-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Effects of cholera toxin and forskolin on pig epidermal adenylate cyclase system were investigated. Both agents increased cyclic AMP levels of epidermis. Marked accumulations were observed in the presence of cyclic AMP phosphodiesterase inhibitor, isobutylmethylxanthine (IBMX). It has been known that hormone-stimulated adenylate cyclase responses are modified by various chemical treatments. Following long term incubation with hydrocortisone, Ro10-1670, and colchicine, the epidermal beta-adrenergic adenylate cyclase response was increased without the alteration of cyclic AMP phosphodiesterase activity. Adenosine-, and histamine-adenylate cyclase responses were unchanged by hydrocortisone treatment, and were decreased by Ro10-1670 and colchicine treatments. Following the long term incubation with these chemicals, effects of cholera toxin and forskolin were investigated. Colchicine-treated skin revealed the increased cholera toxin-, and forskolin-induced cyclic AMP accumulations. Neither hydrocortisone- nor Ro10-1670-treated skin revealed alterations of cholera toxin-, and forskolin-effect. The stimulatory effect of colchicine on the cholera toxin-, and forskolin-effect was observed at doses of the beta-adrenergic augmentation effect. Our results indicate that among the chemicals which reveal the beta-adrenergic augmentation effect, colchicine is unique in that it also increases cholera toxin-, and forskolin-induced cyclic AMP accumulations of epidermis.
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Affiliation(s)
- S Matsuo
- Department of Dermatology, Asahikawa Medical College, Japan
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12
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Iizuka H, Matsuo S, Tamura T, Ohkuma N. Increased cholera toxin-, and forskolin-induced cyclic AMP accumulations in psoriatic involved versus uninvolved or normal human epidermis. J Invest Dermatol 1988; 91:154-7. [PMID: 2456358 DOI: 10.1111/1523-1747.ep12464401] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Psoriatic involved epidermis reveals variously altered receptor-adenylate cyclase responses; among them the most prominent is defective beta-adrenergic adenylate cyclase response, which is normally the major receptor-adenylate cyclase system of human epidermis. It is known that activation of hormone-stimulated adenylate cyclase, a membrane-bound enzyme complex, requires functional coupling of at least 3 distinct subunits: 1) receptor subunit (R), 2) guanine nucleotide binding protein (G), and 3) catalytic subunit (C). The precise nature of the beta-adrenergic defect in the psoriatic epidermis, however, remains to be determined, especially in terms of G and C function. Using the involved and uninvolved skin from psoriatic patients, we investigated effects of cholera toxin (which monitors G-C interaction) and forskolin (which monitors C function) on the adenylate cyclase system of epidermis, which were compared with those of normal human epidermis. Both agents increased cyclic AMP levels of involved, uninvolved, and normal human epidermis. Marked accumulations were observed in the presence of cyclic nucleotide phosphodiesterase inhibitor, isobutyl-methylxanthine (IBMX); without the phosphodiesterase inhibitor, the effect of each agent was minimal. Comparison of the effects of cholera toxin revealed that the psoriatic involved epidermis accumulates much more cyclic AMP than the uninvolved epidermis (involved: 193 +/- 65; uninvolved: 117 +/- 54 pmoles/mg protein/5 h). Similarly forskolin-induced cyclic AMP accumulations of the involved epidermis were much more than those of uninvolved epidermis (involved: 374 +/- 152; uninvolved: 101 +/- 41 pmoles/mg protein/2 h). Those of normal human epidermis were not significantly different from those of uninvolved epidermis (cholera toxin: 99 +/- 36 pmoles/mg protein/5 h; forskolin: 84 +/- 22 pmoles/mg protein/2 h). Our results indicate that G and C function and their interaction is not defective (but rather increased) in the psoriatic involved epidermis. This suggests that the defective beta-adrenergic response of psoriatic involved epidermis reflects defective R or R-G interaction of the epidermal adenylate cyclase system.
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Affiliation(s)
- H Iizuka
- Department of Dermatology, Asahikawa Medical College, Japan
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13
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Wice B, Milbrandt J, Glaser L. Control of muscle differentiation in BC3H1 cells by fibroblast growth factor and vanadate. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(19)75711-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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14
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Kempski O, Wroblewska B, Spatz M. Effects of forskolin on growth and morphology of cultured glial and cerebrovascular endothelial and smooth muscle cells. Int J Dev Neurosci 1987; 5:435-45. [PMID: 2845720 DOI: 10.1016/0736-5748(87)90021-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The present experiments were designed to evaluate the effectiveness of forskolin on cAMP production, growth and morphology on cell cultures of glia, endothelium and smooth muscle derived from brain microvessels. Forskolin significantly increased formation of cAMP and decreased incorporation of thymidine in all three cell types. The thymidine incorporation was reduced dose-dependently with maximal growth inhibition at 100 microM forskolin. A 1 hr preincubation with forskolin abolished thymidine incorporation by cells grown in fetal calf serum (FCS)-containing media over the following 24 hr. In cerebromicrovascular endothelium and smooth muscle, forskolin caused drastic and immediate changes of cell morphology and F-actin composition that were reversible. In glial cells, morphological changes were visible only after exposure to forskolin for more than 24 hr. These changes were accompanied by increased staining with antibodies against glial fibrillary acidic protein (GFAP). These findings support the contention of cAMP involvement in growth regulation of these cells and indicate that forskolin might be used as a tool to induce growth arrest and possible differentiation in cell cultures from mammalian brain.
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Affiliation(s)
- O Kempski
- LNNS, NINCDS, National Institutes of Health, Bethesda, MD 20892
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Shi QH, Ruiz JA, Ho RJ. Forms of adenylate cyclase, activation and/or potentiation by forskolin. Arch Biochem Biophys 1986; 251:156-65. [PMID: 3789730 DOI: 10.1016/0003-9861(86)90062-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Activation of different forms of adenylate cyclases (AC) by forskolin and displacement of [14,15-3H]dihydroforskolin binding from membranes by forskolin in the absence or presence of specific stimulatory hormone and beta, gamma-imidoguanosine 5'-triphosphate (Gpp(NH)p) have been studied. These conditions have been used to generate forskolin dose-response curves of AC activation. A plot of enzyme activation versus apparent forskolin-binding showed a linear and a nonlinear relationship, respectively, in the absence or presence of the other two stimulators. The latter relationship can be fitted by two linear regression lines with a defined intercept, the slopes of which represent two distinct binding-activation (B-A) effects. The B-A effects of forskolin for rat adipocyte and liver membranes in the absence of stimulatory hormone and Gpp(NH)p were 10 and 8 (pmol X min-1) X (pmol)-1, respectively. The B-A effects for the same membranes in the presence of the other two stimulators were 69 (high) and 13 (low) (pmol X min-1) X (pmol)-1 for adipocyte membrane, and 83 (high) and 9 (low) (pmol X min-1) X (pmol)-1 for liver membrane. The ratio of potentiation of forskolin-activated enzyme activity to the unmodified forskolin-stimulated activity (P-A ratio) was determined without the binding data. At 3 microM forskolin, with and without 230 epinephrine and 10 microM Gpp(NH)p, the P-A ratio was 3.7, decreasing to 1.1 with the addition 100 microM forskolin. The line representing a high B-A effect and a resulting high P-A ratio appears to describe the interactions between forskolin and the AC stimulated by epinephrine and Gpp(NH)p. The line of low B-A effect may represent the interaction between forskolin and the basal AC. Two peaks of AC activity were eluted from forskolin-Sepharose column. They have apparent differences in sensitivity to Gpp(NH)p and affinity for forskolin. Based on the results available thus far, with consideration for known limitations of the methodology, a working model has been proposed for forskolin activation of AC.
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Ruiz J, Shi QH, Ho RJ. A dose-response study of forskolin, stimulatory hormone, and guanosine triphosphate analog on adenylate cyclase from several sources. Arch Biochem Biophys 1986; 251:139-47. [PMID: 3024568 DOI: 10.1016/0003-9861(86)90060-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We have described relationships involving forskolin stimulation of adenylate cyclase (AC) from a variety of sources and the potentiation of forskolin effects by stimulatory hormones (glucagon, ACTH, and epinephrine) and beta, gamma-imidoguanosine 5'-triphosphate (Gpp(NH)p). The effects on AC were examined using membrane preparations of rabbit adipocytes, rat adipocytes, rat erythrocytes, and rat liver. Also examined was the AC of liver membranes of rat pretreated with pertussis toxin as well as that solubilized from rat liver membranes. Maximal forskolin stimulation of AC in all preparations studied revealed a consistent 10-fold increase in AC activity. The EC50 for forskolin was 10 microM for rat liver, 15 microM for rabbit and rat adipocytes and 17 microM for rat erythrocyte AC stimulation. In all cases the AC activity attained by forskolin stimulation was further enhanced by stimulatory hormones in a dose-dependent manner. Furthermore, a combination of all three activators (forskolin, stimulatory hormone, and Gpp(NH)p) resulted in an even greater overall stimulation to levels ranging from 25- to 30-fold over unstimulated activity levels. In the presence of saturating levels of each stimulatory hormone and Gpp(NH)p, the EC50 for forskolin diminished markedly to the range of 0.5 to 4.0 microM. In the absence of any apparent tissue specificity for forskolin stimulation, the general pattern of these results further implicates the catalytic site of the AC complex as the site of forskolin activation. Furthermore, activation of additional components of the complex by Gpp(NH)p and tissue specific hormones may further influence the AC activity and thereby potentiate the stimulation by forskolin.
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Rousset M, Laburthe M, Pinto M, Chevalier G, Rouyer-Fessard C, Dussaulx E, Trugnan G, Boige N, Brun JL, Zweibaum A. Enterocytic differentiation and glucose utilization in the human colon tumor cell line Caco-2: modulation by forskolin. J Cell Physiol 1985; 123:377-85. [PMID: 2985631 DOI: 10.1002/jcp.1041230313] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The human colon cancer line Caco-2 exhibits after confluency a concomitant increase of glycogen accumulation and an enterocytic differentiation. The purpose of this work was to investigate whether forskolin (FK), an activator of adenylate cyclase, would induce a permanent glycogenolysis and, if so, whether it would result in modifications of the differentiation pattern of the cells. FK activates adenylate cyclase in Caco-2 cells with an ED50 of 7 X 10(-6)M. Three different treatment protocols with FK (10(-5)M) were applied: 1) the cells were treated during all the time in culture (20 days); 2) the treatment was started after confluency; 3) the treatment was interrupted after confluency. The presence of FK results in a permanent stimulation of cAMP accumulation (10 to 20 fold the basal values) and in a permanently reduced glycogen content (30 or 50% of the control values). The rates of glucose consumption are increased three and five fold in protocols 1 and 3 respectively. These metabolic changes are associated with morphological changes (tightening of the intercellular spaces and shortening of the brush border microvilli) and with a dual inhibition of the activities of brush border hydrolases: a) an inhibition of the post-confluent increase of activity of sucrase, aminopeptidase N and alkaline phosphatase in the brush border enriched fraction; b) an inhibition of the post-confluent increase of activity of sucrase in the cell homogenate. A comparison of the results obtained in each protocol shows that the morphological modifications and the decrease of the enzyme activities in the brush border fraction are regularly associated with an increased cAMP accumulation, whereas the inhibition of the differentiation of sucrase is a direct consequence of the increase in glucose consumption and decrease in glycogen stores.
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Iizuka H, Adachi R, Koizumi H, Aoyagi T, Ohkawara A, Miura Y. Effects of adenosine and 2'-deoxyadenosine on epidermal keratinocyte proliferation: its relation to cyclic AMP formation. J Invest Dermatol 1984; 82:608-12. [PMID: 6327832 DOI: 10.1111/1523-1747.ep12261448] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Although it has been reported that adenosine has an inhibitory effect on keratinocyte proliferation at both G2 and S phases of the cell cycle, its relation to cyclic AMP formation through the adenylate cyclase system has been less well characterized. In order to determine the precise mechanism of the adenosine effect, another physiologic adenine nucleoside, 2'-deoxyadenosine was employed. 2'-Deoxyadenosine was shown to be remarkably different from adenosine in its ability to stimulate the epidermal adenylate cyclase; whereas adenosine markedly increased cyclic AMP levels of pig epidermis, deoxyadenosine had a much weaker effect on the cyclic AMP levels of the skin. Using several parameters of cell proliferation, comparison was made between the effects of these two compounds. Pig keratinocyte explant culture system was employed for the measurement of outgrowth and mitosis. Mitosis was determined after 72-h incubation (to monitor the overall cell proliferation inhibition) and 4-h incubation (to monitor G2 phase inhibition) with the chemicals. Pig skin keratome slice system was employed for [3H]thymidine uptake measurement. Both adenosine and deoxyadenosine were shown to have marked inhibitory effects on keratinocyte out-growth, [3H]thymidine uptake, and keratinocyte mitosis. The effects of deoxyadenosine on outgrowth and [3H]thymidine uptake were greater than that of adenosine. The inhibitory effect of adenosine and deoxyadenosine on mitosis were about the same in both 4-h and 72-h incubation systems. Thus deoxyadenosine, which is a much weaker stimulator of epidermal adenylate cyclase, was also shown to be as potent an inhibitor of keratinocyte proliferation as adenosine. These results further substantiate the view that cyclic AMP elevating agents (such as adenosine and deoxyadenosine) might not necessarily reveal their inhibitory effects on keratinocyte proliferation through their effects of cyclic AMP formation.
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Iizuka H, Kishiyama K, Ohkuma N, Murata H, Ohkawara A. Colchicine-induced alteration of hormone-stimulated cyclic AMP synthesis in pig skin (epidermis). J Invest Dermatol 1984; 82:357-61. [PMID: 6323587 DOI: 10.1111/1523-1747.ep12260687] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Effects of colchicine on the epidermal adenylate cyclase systems were investigated. When pig skin (epidermis) was incubated in RPMI 1640 medium without the addition of serum, the beta-adrenergic adenylate cyclase response (epinephrine-induced cyclic AMP accumulations) gradually decreased, whereas adenosine and histamine responses remained high or increased during the long-term (up to 48 h) incubation period. The addition of colchicine (1 mumol/liter) in the incubation medium resulted in an increase in the beta-adrenergic responsiveness and a decrease in adenosine and histamine responsivenesses. The effects of colchicine were both time- and concentration-dependent; they could be observed after 9-12 h incubation, and the maximal effect was obtained at a concentration of 0.1 mumol/liter. Similar effects were observed by the addition of another microtubule-disruptive agent, vinblastine. On the other hand, cytochalasin B, which affects the microfilament system, apparently decreased the beta-adrenergic response and increased adenosine and histamine responses during the long-term incubation period. The addition of serum in the incubation medium resulted in essentially the same effect as that of colchicine; in the presence of serum, colchicine-treated skin responded much more markedly to epinephrine (and much less to adenosine and histamine) than the control skin after 24- and 48-h incubation. Previously we reported that hydrocortisone has similar potentiating effects on the beta-adrenergic system of epidermis. The comparison of the effects of both compounds revealed that colchicine had a stronger effect than hydrocortisone, and furthermore, the simultaneous addition of both compounds (colchicine and hydrocortisone) in the incubation medium resulted in the more marked increase of beta-adrenergic response than the single addition of each chemical. Our overall results, coupled with the finding that hydrocortisone has no toxic effects on the adenosine- or histamine-adenylate cyclase system of epidermis, suggest that colchicine affects epidermal adenylate cyclase systems probably through a mechanism that is independent of glucocorticoid (hydrocortisone) effect.
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