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Glucose Regulates Microtubule Disassembly and the Dose of Insulin Secretion via Tau Phosphorylation.
Ho KH, Yang X, Osipovich AB, Cabrera O, Hayashi ML, Magnuson MA, Gu G, Kaverina I
(2020) Diabetes 69: 1936-1947
MeSH Terms: Animals, Cyclic AMP-Dependent Protein Kinases, Cyclin-Dependent Kinase 5, Glucose, Glycogen Synthase Kinase 3, Insulin Secretion, Insulin-Secreting Cells, Mice, Microtubules, Phosphorylation, Protein Kinase C, tau Proteins
Show Abstract · Added July 2, 2020
The microtubule cytoskeleton of pancreatic islet β-cells regulates glucose-stimulated insulin secretion (GSIS). We have reported that the microtubule-mediated movement of insulin vesicles away from the plasma membrane limits insulin secretion. High glucose-induced remodeling of microtubule network facilitates robust GSIS. This remodeling involves disassembly of old microtubules and nucleation of new microtubules. Here, we examine the mechanisms whereby glucose stimulation decreases microtubule lifetimes in β-cells. Using real-time imaging of photoconverted microtubules, we demonstrate that high levels of glucose induce rapid microtubule disassembly preferentially in the periphery of individual β-cells, and this process is mediated by the phosphorylation of microtubule-associated protein tau. Specifically, high glucose induces tau hyper-phosphorylation via glucose-responsive kinases GSK3, PKA, PKC, and CDK5. This causes dissociation of tau from and subsequent destabilization of microtubules. Consequently, tau knockdown in mouse islet β-cells facilitates microtubule turnover, causing increased basal insulin secretion, depleting insulin vesicles from the cytoplasm, and impairing GSIS. More importantly, tau knockdown uncouples microtubule destabilization from glucose stimulation. These findings suggest that tau suppresses peripheral microtubules turning over to restrict insulin oversecretion in basal conditions and preserve the insulin pool that can be released following stimulation; high glucose promotes tau phosphorylation to enhance microtubule disassembly to acutely enhance GSIS.
© 2020 by the American Diabetes Association.
2 Communities
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12 MeSH Terms
Protein kinase A-mediated phosphorylation of naked cuticle homolog 2 stimulates cell-surface delivery of transforming growth factor-α for epidermal growth factor receptor transactivation.
Cao Z, Singh B, Li C, Markham NO, Carrington LJ, Franklin JL, Graves-Deal R, Kennedy EJ, Goldenring JR, Coffey RJ
(2019) Traffic 20: 357-368
MeSH Terms: A Kinase Anchor Proteins, Adaptor Proteins, Signal Transducing, Animals, Caco-2 Cells, Calcium-Binding Proteins, Cell Cycle Proteins, Cell Membrane, Cyclic AMP-Dependent Protein Kinases, Dinoprostone, Dogs, ErbB Receptors, HEK293 Cells, Humans, Madin Darby Canine Kidney Cells, Protein Transport, Signal Transduction, Transforming Growth Factor alpha, Vasoactive Intestinal Peptide
Show Abstract · Added March 3, 2020
The classic mode of G protein-coupled receptor (GPCR)-mediated transactivation of the receptor tyrosine kinase epidermal growth factor receptor (EGFR) transactivation occurs via matrix metalloprotease (MMP)-mediated cleavage of plasma membrane-anchored EGFR ligands. Herein, we show that the Gαs-activating GPCR ligands vasoactive intestinal peptide (VIP) and prostaglandin E (PGE ) transactivate EGFR through increased cell-surface delivery of the EGFR ligand transforming growth factor-α (TGFα) in polarizing madin-darby canine kidney (MDCK) and Caco-2 cells. This is achieved by PKA-mediated phosphorylation of naked cuticle homolog 2 (NKD2), previously shown to bind TGFα and direct delivery of TGFα-containing vesicles to the basolateral surface of polarized epithelial cells. VIP and PGE rapidly activate protein kinase A (PKA) that then phosphorylates NKD2 at Ser-223, a process that is facilitated by the molecular scaffold A-kinase anchoring protein 12 (AKAP12). This phosphorylation stabilized NKD2, ensuring efficient cell-surface delivery of TGFα and increased EGFR activation. Thus, GPCR-triggered, PKA/AKAP12/NKD2-regulated targeting of TGFα to the cell surface represents a new mode of EGFR transactivation that occurs proximal to ligand cleavage by MMPs.
© 2019 The Authors. Traffic published by John Wiley & Sons Ltd.
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18 MeSH Terms
Second messenger signaling mechanisms of the brown adipocyte thermogenic program: an integrative perspective.
Shi F, Collins S
(2017) Horm Mol Biol Clin Investig 31:
MeSH Terms: Adipocytes, Beige, Adipocytes, Brown, Animals, Cyclic AMP-Dependent Protein Kinases, Cyclic GMP-Dependent Protein Kinases, Energy Metabolism, Gene Expression Regulation, Humans, Intracellular Space, Mechanistic Target of Rapamycin Complex 1, MicroRNAs, Natriuretic Agents, RNA, Long Noncoding, Receptors, Adrenergic, beta, Second Messenger Systems, Signal Transduction, Thermogenesis, Uncoupling Protein 1
Show Abstract · Added September 26, 2018
β-adrenergic receptors (βARs) are well established for conveying the signal from catecholamines to adipocytes. Acting through the second messenger cyclic adenosine monophosphate (cAMP) they stimulate lipolysis and also increase the activity of brown adipocytes and the 'browning' of adipocytes within white fat depots (so-called 'brite' or 'beige' adipocytes). Brown adipose tissue mitochondria are enriched with uncoupling protein 1 (UCP1), which is a regulated proton channel that allows the dissipation of chemical energy in the form of heat. The discovery of functional brown adipocytes in humans and inducible brown-like ('beige' or 'brite') adipocytes in rodents have suggested that recruitment and activation of these thermogenic adipocytes could be a promising strategy to increase energy expenditure for obesity therapy. More recently, the cardiac natriuretic peptides and their second messenger cyclic guanosine monophosphate (cGMP) have gained attention as a parallel signaling pathway in adipocytes, with some unique features. In this review, we begin with some important historical work that touches upon the regulation of brown adipocyte development and physiology. We then provide a synopsis of some recent advances in the signaling cascades from β-adrenergic agonists and natriuretic peptides to drive thermogenic gene expression in the adipocytes and how these two pathways converge at a number of unexpected points. Finally, moving from the physiologic hormonal signaling, we discuss yet another level of control downstream of these signals: the growing appreciation of the emerging roles of non-coding RNAs as important regulators of brown adipocyte formation and function. In this review, we discuss new developments in our understanding of the signaling mechanisms and factors including new secreted proteins and novel non-coding RNAs that control the function as well as the plasticity of the brown/beige adipose tissue as it responds to the energy needs and environmental conditions of the organism.
0 Communities
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MeSH Terms
Efferocytosis-induced prostaglandin E2 production impairs alveolar macrophage effector functions during Streptococcus pneumoniae infection.
Salina AC, Souza TP, Serezani CH, Medeiros AI
(2017) Innate Immun 23: 219-227
MeSH Terms: Animals, Apoptosis, Bacteriolysis, Cyclic AMP, Cyclic AMP-Dependent Protein Kinases, Dinoprostone, Female, Homeostasis, Humans, Hydrogen Peroxide, Jurkat Cells, Macrophages, Alveolar, Phagocytosis, Pneumococcal Infections, Rats, Rats, Wistar, Receptors, Prostaglandin E, EP2 Subtype, Receptors, Prostaglandin E, EP4 Subtype, Signal Transduction, Streptococcus pneumoniae
Show Abstract · Added May 4, 2017
Alveolar macrophages (AMs) are multitasking cells that maintain lung homeostasis by clearing apoptotic cells (efferocytosis) and performing antimicrobial effector functions. Different PRRs have been described to be involved in the binding and capture of non-opsonized Streptococcus pneumoniae, such as TLR-2, mannose receptor (MR) and scavenger receptors (SRs). However, the mechanism by which the ingestion of apoptotic cells negatively influences the clearance of non-opsonized S. pneumoniae remains to be determined. In this study, we evaluated whether the prostaglandin E2 (PGE) produced during efferocytosis by AMs inhibits the ingestion and killing of non-opsonized S. pneumoniae. Resident AMs were pre-treated with an E prostanoid (EP) receptor antagonist, inhibitors of cyclooxygenase and protein kinase A (PKA), incubated with apoptotic Jurkat T cells, and then challenged with S. pneumoniae. Efferocytosis slightly decreased the phagocytosis of S. pneumoniae but greatly inhibited bacterial killing by AMs in a manner dependent on PGE production, activation of the EP2-EP4/cAMP/PKA pathway and inhibition of HO production. Our data suggest that the PGE produced by AMs during efferocytosis inhibits HO production and impairs the efficient clearance non-opsonized S. pneumoniae by EP2-EP4/cAMP/PKA pathway.
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20 MeSH Terms
Activation of mTORC1 is essential for β-adrenergic stimulation of adipose browning.
Liu D, Bordicchia M, Zhang C, Fang H, Wei W, Li JL, Guilherme A, Guntur K, Czech MP, Collins S
(2016) J Clin Invest 126: 1704-16
MeSH Terms: 3T3-L1 Cells, Adaptor Proteins, Signal Transducing, Adipose Tissue, Brown, Adipose Tissue, White, Animals, Cyclic AMP-Dependent Protein Kinases, HEK293 Cells, Humans, Insulin, Mechanistic Target of Rapamycin Complex 1, Mice, Mice, Knockout, Multiprotein Complexes, Receptors, Adrenergic, beta, Regulatory-Associated Protein of mTOR, Ribosomal Protein S6 Kinases, 70-kDa, Ribosomal Protein S6 Kinases, 90-kDa, Signal Transduction, TOR Serine-Threonine Kinases, Uncoupling Protein 1
Show Abstract · Added July 22, 2020
A classic metabolic concept posits that insulin promotes energy storage and adipose expansion, while catecholamines stimulate release of adipose energy stores by hydrolysis of triglycerides through β-adrenergic receptor (βARs) and protein kinase A (PKA) signaling. Here, we have shown that a key hub in the insulin signaling pathway, activation of p70 ribosomal S6 kinase (S6K1) through mTORC1, is also triggered by PKA activation in both mouse and human adipocytes. Mice with mTORC1 impairment, either through adipocyte-specific deletion of Raptor or pharmacologic rapamycin treatment, were refractory to the well-known βAR-dependent increase of uncoupling protein UCP1 expression and expansion of beige/brite adipocytes (so-called browning) in white adipose tissue (WAT). Mechanistically, PKA directly phosphorylated mTOR and RAPTOR on unique serine residues, an effect that was independent of insulin/AKT signaling. Abrogation of the PKA site within RAPTOR disrupted βAR/mTORC1 activation of S6K1 without affecting mTORC1 activation by insulin. Conversely, a phosphomimetic RAPTOR augmented S6K1 activity. Together, these studies reveal a signaling pathway from βARs and PKA through mTORC1 that is required for adipose browning by catecholamines and provides potential therapeutic strategies to enhance energy expenditure and combat metabolic disease.
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MeSH Terms
Opposing roles of LTB4 and PGE2 in regulating the inflammasome-dependent scorpion venom-induced mortality.
Zoccal KF, Sorgi CA, Hori JI, Paula-Silva FW, Arantes EC, Serezani CH, Zamboni DS, Faccioli LH
(2016) Nat Commun 7: 10760
MeSH Terms: Animals, Arachidonate 5-Lipoxygenase, Blotting, Western, Carrier Proteins, Celecoxib, Cyclic AMP, Cyclic AMP-Dependent Protein Kinases, Cyclooxygenase Inhibitors, Dinoprostone, In Vitro Techniques, Indoles, Indomethacin, Inflammasomes, Interleukin-1beta, Leukotriene B4, Lipoxygenase Inhibitors, Macrophages, Macrophages, Peritoneal, Mice, Mice, Knockout, NF-kappa B, NLR Family, Pyrin Domain-Containing 3 Protein, Phosphoproteins, Prostaglandin Antagonists, Receptors, Prostaglandin E, EP2 Subtype, Receptors, Prostaglandin E, EP4 Subtype, Reverse Transcriptase Polymerase Chain Reaction, Scorpion Stings, Scorpion Venoms, Scorpions, Xanthones
Show Abstract · Added May 4, 2017
Tityus serrulatus sting causes thousands of deaths annually worldwide. T. serrulatus-envenomed victims exhibit local or systemic reaction that culminates in pulmonary oedema, potentially leading to death. However, the molecular mechanisms underlying T. serrulatus venom (TsV) activity remain unknown. Here we show that TsV triggers NLRP3 inflammasome activation via K(+) efflux. Mechanistically, TsV triggers lung-resident cells to release PGE2, which induces IL-1β production via E prostanoid receptor 2/4-cAMP-PKA-NFκB-dependent mechanisms. IL-1β/IL-1R actions account for oedema and neutrophil recruitment to the lungs, leading to TsV-induced mortality. Inflammasome activation triggers LTB4 production and further PGE2 via IL-1β/IL-1R signalling. Activation of LTB4-BLT1/2 pathway decreases cAMP generation, controlling TsV-induced inflammation. Exogenous administration confirms LTB4 anti-inflammatory activity and abrogates TsV-induced mortality. These results suggest that the balance between LTB4 and PGE2 determines the amount of IL-1β inflammasome-dependent release and the outcome of envenomation. We suggest COX1/2 inhibition as an effective therapeutic intervention for scorpion envenomation.
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31 MeSH Terms
An in vivo chemical genetic screen identifies phosphodiesterase 4 as a pharmacological target for hedgehog signaling inhibition.
Williams CH, Hempel JE, Hao J, Frist AY, Williams MM, Fleming JT, Sulikowski GA, Cooper MK, Chiang C, Hong CC
(2015) Cell Rep 11: 43-50
MeSH Terms: Animals, Cyclic AMP-Dependent Protein Kinases, Cyclic Nucleotide Phosphodiesterases, Type 4, Hedgehog Proteins, Phosphodiesterase 4 Inhibitors, Pyrimidinones, Receptors, G-Protein-Coupled, Signal Transduction, Small Molecule Libraries, Smoothened Receptor, Thiophenes, Transcriptional Activation, Zebrafish, Zebrafish Proteins
Show Abstract · Added April 5, 2015
Hedgehog (Hh) signaling plays an integral role in vertebrate development, and its dysregulation has been accepted widely as a driver of numerous malignancies. While a variety of small molecules target Smoothened (Smo) as a strategy for Hh inhibition, Smo gain-of-function mutations have limited their clinical implementation. Modulation of targets downstream of Smo could define a paradigm for treatment of Hh-dependent cancers. Here, we describe eggmanone, a small molecule identified from a chemical genetic zebrafish screen, which induced an Hh-null phenotype. Eggmanone exerts its Hh-inhibitory effects through selective antagonism of phosphodiesterase 4 (PDE4), leading to protein kinase A activation and subsequent Hh blockade. Our study implicates PDE4 as a target for Hh inhibition, suggests an improved strategy for Hh-dependent cancer therapy, and identifies a unique probe of downstream-of-Smo Hh modulation.
Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
1 Communities
3 Members
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14 MeSH Terms
MicroRNA 21 is a homeostatic regulator of macrophage polarization and prevents prostaglandin E2-mediated M2 generation.
Wang Z, Brandt S, Medeiros A, Wang S, Wu H, Dent A, Serezani CH
(2015) PLoS One 10: e0115855
MeSH Terms: Acetylcysteine, Animals, Cell Polarity, Cyclic AMP-Dependent Protein Kinases, Dinoprostone, Erythromycin, Female, Gene Silencing, Homeostasis, Macrophage Activation, Macrophages, Mice, Mice, Knockout, MicroRNAs, STAT3 Transcription Factor, Suppressor of Cytokine Signaling 1 Protein, Suppressor of Cytokine Signaling Proteins
Show Abstract · Added May 4, 2017
Macrophages dictate both initiation and resolution of inflammation. During acute inflammation classically activated macrophages (M1) predominate, and during the resolution phase alternative macrophages (M2) are dominant. The molecular mechanisms involved in macrophage polarization are understudied. MicroRNAs are differentially expressed in M1 and M2 macrophages that influence macrophage polarization. We identified a role of miR-21 in macrophage polarization, and found that cross-talk between miR-21 and the lipid mediator prostaglandin E2 (PGE2) is a determining factor in macrophage polarization. miR-21 inhibition impairs expression of M2 signature genes but not M1 genes. PGE2 and its downstream effectors PKA and Epac inhibit miR-21 expression and enhance expression of M2 genes, and this effect is more pronounced in miR-21-/- cells. Among potential targets involved in macrophage polarization, we found that STAT3 and SOCS1 were enhanced in miR-21-/- cells and further enhanced by PGE2. We found that STAT3 was a direct target of miR-21 in macrophages. Silencing the STAT3 gene abolished PGE2-mediated expression of M2 genes in miR-21-/- macrophages. These data shed light on the molecular brakes involved in homeostatic macrophage polarization and suggest new therapeutic strategies to prevent inflammatory responses.
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17 MeSH Terms
Somatostatin and insulin mediate glucose-inhibited glucagon secretion in the pancreatic α-cell by lowering cAMP.
Elliott AD, Ustione A, Piston DW
(2015) Am J Physiol Endocrinol Metab 308: E130-43
MeSH Terms: Animals, Cyclic AMP, Cyclic AMP-Dependent Protein Kinases, Flow Cytometry, Glucagon, Glucagon-Secreting Cells, Glucose, Humans, Insulin, Islets of Langerhans, Male, Mice, Mice, Inbred C57BL, Microscopy, Confocal, Signal Transduction, Somatostatin
Show Abstract · Added January 20, 2015
The dysregulation of glucose-inhibited glucagon secretion from the pancreatic islet α-cell is a critical component of diabetes pathology and metabolic disease. We show a previously uncharacterized [Ca(2+)]i-independent mechanism of glucagon suppression in human and murine pancreatic islets whereby cAMP and PKA signaling are decreased. This decrease is driven by the combination of somatostatin, which inhibits adenylyl cyclase production of cAMP via the Gαi subunit of the SSTR2, and insulin, which acts via its receptor to activate phosphodiesterase 3B and degrade cytosolic cAMP. Our data indicate that both somatostatin and insulin signaling are required to suppress cAMP/PKA and glucagon secretion from both human and murine α-cells, and the combination of these two signaling mechanisms is sufficient to reduce glucagon secretion from isolated α-cells as well as islets. Thus, we conclude that somatostatin and insulin together are critical paracrine mediators of glucose-inhibited glucagon secretion and function by lowering cAMP/PKA signaling with increasing glucose.
Copyright © 2015 the American Physiological Society.
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2 Members
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16 MeSH Terms
PACAP induces plasticity at autonomic synapses by nAChR-dependent NOS1 activation and AKAP-mediated PKA targeting.
Jayakar SS, Pugh PC, Dale Z, Starr ER, Cole S, Margiotta JF
(2014) Mol Cell Neurosci 63: 1-12
MeSH Terms: A Kinase Anchor Proteins, Animals, Autonomic Nervous System, Calcium, Cells, Cultured, Chick Embryo, Cyclic AMP-Dependent Protein Kinases, Neuronal Plasticity, Neurons, Nitric Oxide, Nitric Oxide Synthase Type I, Pituitary Adenylate Cyclase-Activating Polypeptide, Protein Binding, Receptors, Nicotinic, Synapses
Show Abstract · Added June 2, 2015
Pituitary adenylate cyclase-activating polypeptide (PACAP) is a pleiotropic neuropeptide found at synapses throughout the central and autonomic nervous system. We previously found that PACAP engages a selective G-protein coupled receptor (PAC1R) on ciliary ganglion neurons to rapidly enhance quantal acetylcholine (ACh) release from presynaptic terminals via neuronal nitric oxide synthase (NOS1) and cyclic AMP/protein kinase A (PKA) dependent processes. Here, we examined how PACAP stimulates NO production and targets resultant outcomes to synapses. Scavenging extracellular NO blocked PACAP-induced plasticity supporting a retrograde (post- to presynaptic) NO action on ACh release. Live-cell imaging revealed that PACAP stimulates NO production by mechanisms requiring NOS1, PKA and Ca(2+) influx. Ca(2+)-permeable nicotinic ACh receptors composed of α7 subunits (α7-nAChRs) are potentiated by PKA-dependent PACAP/PAC1R signaling and were required for PACAP-induced NO production and synaptic plasticity since both outcomes were drastically reduced following their selective inhibition. Co-precipitation experiments showed that NOS1 associates with α7-nAChRs, many of which are perisynaptic, as well as with heteromeric α3*-nAChRs that generate the bulk of synaptic activity. NOS1-nAChR physical association could facilitate NO production at perisynaptic and adjacent postsynaptic sites to enhance focal ACh release from juxtaposed presynaptic terminals. The synaptic outcomes of PACAP/PAC1R signaling are localized by PKA anchoring proteins (AKAPs). PKA regulatory-subunit overlay assays identified five AKAPs in ganglion lysates, including a prominent neuronal subtype. Moreover, PACAP-induced synaptic plasticity was selectively blocked when PKA regulatory-subunit binding to AKAPs was inhibited. Taken together, our findings indicate that PACAP/PAC1R signaling coordinates nAChR, NOS1 and AKAP activities to induce targeted, retrograde plasticity at autonomic synapses. Such coordination has broad relevance for understanding the control of autonomic synapses and consequent visceral functions.
Copyright © 2014 Elsevier Inc. All rights reserved.
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15 MeSH Terms