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Mariño G, Pietrocola F, Madeo F, Kroemer G. Caloric restriction mimetics: natural/physiological pharmacological autophagy inducers. Autophagy 2014; 10:1879-82. [PMID: 25484097 PMCID: PMC4502795 DOI: 10.4161/auto.36413] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 09/05/2014] [Accepted: 09/27/2014] [Indexed: 01/12/2023] Open
Abstract
Nutrient depletion, which is one of the physiological triggers of autophagy, results in the depletion of intracellular acetyl coenzyme A (AcCoA) coupled to the deacetylation of cellular proteins. We surmise that there are 3 possibilities to mimic these effects, namely (i) the depletion of cytosolic AcCoA by interfering with its biosynthesis, (ii) the inhibition of acetyltransferases, which are enzymes that transfer acetyl groups from AcCoA to other molecules, mostly leucine residues in cellular proteins, or (iii) the stimulation of deacetylases, which catalyze the removal of acetyl groups from leucine residues. There are several examples of rather nontoxic natural compounds that act as AcCoA depleting agents (e.g., hydroxycitrate), acetyltransferase inhibitors (e.g., anacardic acid, curcumin, epigallocatechin-3-gallate, garcinol, spermidine) or deacetylase activators (e.g., nicotinamide, resveratrol), and that are highly efficient inducers of autophagy in vitro and in vivo, in rodents. Another common characteristic of these agents is their capacity to reduce aging-associated diseases and to confer protective responses against ischemia-induced organ damage. Hence, we classify them as "caloric restriction mimetics" (CRM). Here, we speculate that CRM may mediate their broad health-improving effects by triggering the same molecular pathways that usually are elicited by long-term caloric restriction or short-term starvation and that imply the induction of autophagy as an obligatory event conferring organismal, organ- or cytoprotection.
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Affiliation(s)
- Guillermo Mariño
- Equipe 11 labellisée par la Ligue Nationale contre le cancer; INSERM U1138; Center de Recherche des Cordeliers; Paris, France
- Université Paris Descartes; Sorbonne Paris Cité; Paris, France
| | - Federico Pietrocola
- Equipe 11 labellisée par la Ligue Nationale contre le cancer; INSERM U1138; Center de Recherche des Cordeliers; Paris, France
- Université de Paris Sud; Villejuif, France
| | - Frank Madeo
- Institute of Molecular Biosciences; University of Graz; Graz, Austria
| | - Guido Kroemer
- Equipe 11 labellisée par la Ligue Nationale contre le cancer; INSERM U1138; Center de Recherche des Cordeliers; Paris, France
- Université Paris Descartes; Sorbonne Paris Cité; Paris, France
- Metabolomics and Molecular Cell Biology Platforms; Gustave Roussy; Villejuif, France
- Pôle de Biologie; Hôpital Européen Georges Pompidou; AP-HP; Paris, France
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Abstract
The focus of this review is the regulated trafficking of the cystic fibrosis transmembrane conductance regulator (CFTR) in distal compartments of the protein secretory pathway and the question of how changes in CFTR cellular distribution may impact on the functions of polarized epithelial cells. We summarize data concerning the cellular localization and activity of CFTR and attempt to synthesize often conflicting results from functional studies of regulated endocytosis and exocytosis in CFTR-expressing cells. In some instances, findings that are inconsistent with regulated CFTR trafficking may result from the use of overexpression systems or nonphysiological experimental conditions. Nevertheless, judging from data on other transporters, an appropriate cellular context is necessary to support regulated CFTR trafficking, even in epithelial cells. The discovery that disease mutations can influence CFTR trafficking in distal secretory and recycling compartments provides support for the concept that regulated CFTR recycling contributes to normal epithelial function, including the control of apical CFTR channel density and epithelial protein secretion. Finally, we propose molecular mechanisms for regulated CFTR endocytosis and exocytosis that are based on CFTR interactions with other proteins, particularly those whose primary function is membrane trafficking. These models provide testable hypotheses that may lead to elucidation of CFTR trafficking mechanisms and permit their experimental manipulation in polarized epithelial cells.
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Affiliation(s)
- Carol A Bertrand
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, S362 BST, 3500 Terrace St, Pittsburgh, PA 15261, USA.
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Botchkin LM, Matthews G. Swelling activates chloride current and increases internal calcium in nonpigmented epithelial cells from the rabbit ciliary body. J Cell Physiol 1995; 164:286-94. [PMID: 7622578 DOI: 10.1002/jcp.1041640209] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Membrane current and [Ca]i in rabbit nonpigmented ciliary body epithelial cells (NPE cells) were monitored with combined patch-clamp and fura-2 measurements during cell swelling induced by anisosmotic conditions. In the presence of K-channel blockers, cell swelling produced an increase in membrane current, accompanied by an increase in [Ca]i. Structural changes in the cell, associated with membrane deformation, may be the cause of the increase in [Ca]i during swelling. The conductance activated by swelling was permeable to Cl: it was dependent on the Cl concentration gradient across the cell membrane, and it was blocked by the Cl-channel blockers DIDS, SITS, NPPB, and DIOA. Although swelling increased both Cl current and [Ca]i, there was no evidence that Ca was involved in the regulation of the Cl conductance. Cell swelling activated the current even when [Ca]i was strongly buffered at an elevated level (500 nM) or at a low level (approximately 0) with internal Ca-BAPTA/Cs-BAPTA mixtures. In addition, Cl conductance was unaffected when [Ca]i was increased with a Ca ionophore. There was also no evidence that cAMP participates in the regulation of the Cl conductance: swelling activation of the current occurred in the presence of cAMP inhibitor (Rp-cAMP-S) and cAMP mimic (Sp-cAMP-S). The data suggest independent involvement of Cl conductance and internal Ca in the regulation of cell volume in NPE cells.
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Affiliation(s)
- L M Botchkin
- Department of Neurobiology and Behavior, State University of New York, Stony Brook 11794-5230, USA
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4
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Abstract
Recent evidence strongly suggests that the cystic fibrosis gene product (CFTR) is a Cl- channel. Its properties, however, differ from those of a 30-50 pS outwardly rectifying channel previously implicated as defective in cystic fibrosis. It is still uncertain whether the pleiotropic effects of the CF defect, such as increased airway Na+ absorption and mucus sulfation, are secondary to reduced Cl- conductance, or reflect additional functions of CFTR.
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Affiliation(s)
- J H Widdicombe
- Cystic Fibrosis Research Center, University of California, San Francisco 94143
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5
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Abstract
The high incidence of cystic fibrosis (CF) in most European populations (and populations of European descent) can be explained by different hypotheses that can be tested using the available data concerning this disorder. Among the five hypotheses discussed (genetic heterogeneity, high rate of mutation, meiotic drive, drift and heterozygote advantage), only the last is supported by experimental data. The following conclusions can be drawn from the evidence that we have reviewed: (1) CF is a single gene disorder (genetically homogeneous). (2) Haplotypes associated with the CF gene suggest that only a few mutations (the same gene located in 7q13 is always affected) are responsible for the disorder. (3) CF with pancreatic insufficiency is mainly associated with a single haplotype, whereas CF with pancreatic sufficiency is more frequently associated with different haplotypes. (4) A selective advantage consisting of higher resistance to Cl- -secreting diarrhoeas might have favored, in the past, survival of infants heterozygous for the CF gene.
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Affiliation(s)
- G Romeo
- Laboratorio di Genetica Molecolare, Istituto G. Gaslini, Genova, Italy
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6
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Matthews G, Neher E, Penner R. Chloride conductance activated by external agonists and internal messengers in rat peritoneal mast cells. J Physiol 1989; 418:131-44. [PMID: 2559969 PMCID: PMC1189962 DOI: 10.1113/jphysiol.1989.sp017831] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
1. Stimulation of mast cells by externally applied secretagogues activated a slowly developing membrane current. With high external and low internal chloride (Cl-) concentrations, the current reversed at about -40 mV, but when external Cl- was made equal to internal Cl-, the reversal potential shifted to about 0 mV, demonstrating that the current carrier was Cl-. 2. In addition to external agonists, internally applied cyclic AMP and high concentrations of intracellular calcium [Ca2+]i could also activate the Cl- current. However, elevated [Ca2+]i produced only slow and incomplete activation. This suggests that the Cl- current is not directly Ca2+ activated. Also, activation of Cl- current by external agonists and by cyclic AMP was unimpaired when [Ca2+]i was clamped to low levels with internal ethylene glycol bis-N,N,N',N'-tetraacetic acid (EGTA), indicating that elevated [Ca2+]i is not necessary for activation of the Cl- current. Although activation by cyclic AMP was faster than that produced by elevated [Ca2+]i, it still required tens of seconds; thus the effect of cyclic AMP was also likely to be indirect. 3. Internal guanosine 5'-O-(3-thiotriphosphate) (GTP-gamma-S) could also activate the Cl- current, suggesting the involvement of a G protein in the control of the current. 4. The variance associated with the Cl- current was small, and noise analysis gave a lower limit of about 1-2 pS for the single-channel conductance. The Cl- current was reduced by 4,4'-diisothiocyano-2,2'-stilbenedisulphonate (DIDS), and during DIDS blockade, the variance of the current increased. This suggests that DIDS enters and blocks the open channel. 5. Activation of the Cl- current would make the membrane potential negative following stimulation of a mast cell, thus providing a driving force for entry of external calcium via the stimulation-induced influx pathways described in the preceding paper (Matthews, Neher & Penner, 1989).
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Affiliation(s)
- G Matthews
- Max-Planck-Institut für biophysikalische Chemie, Göttingen, FRG
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Shori DK, Dormer RL, Goodchild MC, McPherson MA. Defective phosphorylation of a calmodulin-binding protein in cystic-fibrosis submandibular glands. Biochem J 1989; 263:613-6. [PMID: 2557002 PMCID: PMC1133472 DOI: 10.1042/bj2630613] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Calmodulin-binding proteins in fractions purified from human submandibular glands by calmodulin-Sepharose were phosphorylated with [gamma-32P]ATP, in the absence of exogenous protein kinase. The major proteins phosphorylated had molecular masses of 45, 51 and 61 kDa. Phosphorylation was increased by activators of protein kinase C and inhibited by H-7. Phosphorylation of the 61 kDa band was markedly decreased in cystic-fibrosis submandibular glands.
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Affiliation(s)
- D K Shori
- Department of Medical Biochemistry, University of Wales College of Medicine, Cardiff, U.K
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Murao S, Collart FR, Huberman E. A protein containing the cystic fibrosis antigen is an inhibitor of protein kinases. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)83189-1] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Doughney C, Pedersen PS, McPherson MA, Dormer RL. Formation of inositol polyphosphates in cultured human sweat duct cells in response to cholinergic stimulation. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 1010:352-6. [PMID: 2920183 DOI: 10.1016/0167-4889(89)90061-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Inositol phosphate formation in response to cholinergic stimulation was studied in cultured human sweat duct cells, prelabelled with myo-[2-3H]inositol. Formation of inositol mono-, bis-, tris- and tetrakisphosphates was increased after 15 min stimulation by 30 microM carbachol. Formation of inositol 1,3,4-trisphosphate and inositol tetrakisphosphate was significantly increased within 1 min at carbachol concentrations between 10 microM and 100 microM. No detectable increase in inositol 1,4,5-trisphosphate formation was observed at 15 s or 1 min, but an increase was observed after 15 min at a carbachol concentration of 30-100 microM. The data are consistent with an involvement of inositol polyphosphates in the biphasic response of ion transport, to cholinergic stimulation in these cells (see Pederson, P.S. (1986) 6th Professional Conference "Broken Arrow 1986". Genetic and Eptihelial Dysfunction in Cystic Fibrosis (Riordan, J.R. and Buchwalds, M., eds.), Alan Liss, New York and Pedersen, P.S. (1987) Med. Sci. Res. 15, 769-770) and suggest a different pattern of metabolism from exocrine acinar cells.
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Affiliation(s)
- C Doughney
- Department of Medical Biochemistry, University of Wales College of Medicine, Cardiff, U.K
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Penner R, Matthews G, Neher E. Regulation of calcium influx by second messengers in rat mast cells. Nature 1988; 334:499-504. [PMID: 2457169 DOI: 10.1038/334499a0] [Citation(s) in RCA: 386] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Biphasic increases in the free intracellular calcium concentration, consisting of a large initial transient followed by a sustained elevation, are frequently observed in non-excitable cells following stimulation. In rat peritoneal mast cells a cAMP- and Ca-activated chloride current can interact with IP3-dependent calcium influx to provide the sustained elevation of intracellular Ca concentration following transient IP3-induced release of calcium from intracellular stores. This novel combination of second messenger systems provides a flexible means to modulate calcium-dependent processes such as exocytosis.
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Affiliation(s)
- R Penner
- Max-Planck-Institut für Biophysikalische Chemie, Göttingen, FRG
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Bradbury NA, McPherson MA. Isoproterenol-induced desensitization of mucin release in isolated rat submandibular acini. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 970:363-70. [PMID: 2456789 DOI: 10.1016/0167-4889(88)90136-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Release of [14C]glucosamine-labelled mucins was studied in vitro using well-characterised preparations of rat submandibular acini. Mucin release was stimulated by forskolin, an activator of the catalytic subunit of adenylate cyclase, and 3-isobutyl-1-methylxanthine (IBMX), a cyclic nucleotide phosphodiesterase inhibitor. Both stimulated in a dose-dependent manner to the same maximum as that seen with isoproterenol. Neither forskolin nor IBMX added in the presence of isoproterenol increased secretion above the maximum in response to isoproterenol alone, suggesting a similar mechanism of action, mediated by cyclic AMP. Prior exposure of acini to isoproterenol (10 microM) for 45 min, followed by washout resulted in (a) persistent increase in basal secretion which was abolished by propranolol and (b) reduced stimulation of mucin secretion in response to either a second isoproterenol challenge, noradrenaline or forskolin. Thus, exposure of rat submandibular acini in vitro desensitizes the cells to subsequent stimulation. Although this mimics the decreased beta-adrenergic secretory responses seen in submandibular cells from cystic fibrosis patients, results suggest that the isoproterenol-induced desensitization is at the level of beta-receptor and adenylate cyclase, rather than distal to cyclic AMP.
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Affiliation(s)
- N A Bradbury
- Department of Medical Biochemistry, University of Wales College of Medicine, Cardiff, U.K
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Abstract
Cystic fibrosis, one of the most common lethal inherited disorders in N. European and N. American populations, is characterized by the production of abnormally viscous mucous secretions in the lungs and digestive tract. The pathophysiological basis of the disease is unknown. However, during the last few years, rapid advances in molecular genetics and biochemical and physiological studies on cystic fibrosis epithelial cells have led to optimism that the cystic fibrosis defect will soon be identified. Current evidence suggests that the basic disturbance lies in altered regulation of protein secretion and electrolyte transport leading to an imbalance in composition of epithelial secretions in cystic fibrosis patients. Increasing knowledge of the mechanisms regulating production and secretion of mucins and movement of electrolytes across the cell membrane should lead to development of pharmacological manipulation(s) to correct the cellular abnormality. Ultimately, it is hoped that this will lead to the development of a rational treatment for cystic fibrosis patients.
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Affiliation(s)
- M A McPherson
- Department of Medical Biochemistry, University of Wales College of Medicine, Heath Park, UK
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