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Nagliya D, Baggio Lopez T, Del Calvo G, Stoicovy RA, Borges JI, Suster MS, Lymperopoulos A. Differential Modulation of Catecholamine and Adipokine Secretion by the Short Chain Fatty Acid Receptor FFAR3 and α 2-Adrenergic Receptors in PC12 Cells. Int J Mol Sci 2024; 25:5227. [PMID: 38791266 PMCID: PMC11120680 DOI: 10.3390/ijms25105227] [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: 03/23/2024] [Revised: 04/29/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
Sympathetic nervous system (SNS) hyperactivity is mediated by elevated catecholamine (CA) secretion from the adrenal medulla, as well as enhanced norepinephrine (NE) release from peripheral sympathetic nerve terminals. Adrenal CA production from chromaffin cells is tightly regulated by sympatho-inhibitory α2-adrenergic (auto)receptors (ARs), which inhibit both epinephrine (Epi) and NE secretion via coupling to Gi/o proteins. α2-AR function is, in turn, regulated by G protein-coupled receptor (GPCR)-kinases (GRKs), especially GRK2, which phosphorylate and desensitize them, i.e., uncouple them from G proteins. On the other hand, the short-chain free fatty acid (SCFA) receptor (FFAR)-3, also known as GPR41, promotes NE release from sympathetic neurons via the Gi/o-derived free Gβγ-activated phospholipase C (PLC)-β/Ca2+ signaling pathway. However, whether it exerts a similar effect in adrenal chromaffin cells is not known at present. In the present study, we examined the interplay of the sympatho-inhibitory α2A-AR and the sympatho-stimulatory FFAR3 in the regulation of CA secretion from rat adrenal chromaffin (pheochromocytoma) PC12 cells. We show that FFAR3 promotes CA secretion, similarly to what GRK2-dependent α2A-AR desensitization does. In addition, FFAR3 activation enhances the effect of the physiologic stimulus (acetylcholine) on CA secretion. Importantly, GRK2 blockade to restore α2A-AR function or the ketone body beta-hydroxybutyrate (BHB or 3-hydroxybutyrate), via FFAR3 antagonism, partially suppress CA production, when applied individually. When combined, however, CA secretion from PC12 cells is profoundly suppressed. Finally, propionate-activated FFAR3 induces leptin and adiponectin secretion from PC12 cells, two important adipokines known to be involved in tissue inflammation, and this effect of FFAR3 is fully blocked by the ketone BHB. In conclusion, SCFAs can promote CA and adipokine secretion from adrenal chromaffin cells via FFAR3 activation, but the metabolite/ketone body BHB can effectively inhibit this action.
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Affiliation(s)
| | | | | | | | | | | | - Anastasios Lymperopoulos
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), Barry and Judy Silverman College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, USA; (D.N.); (T.B.L.); (G.D.C.); (R.A.S.); (J.I.B.); (M.S.S.)
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Permissive Modulation of Sphingosine-1-Phosphate-Enhanced Intracellular Calcium on BK Ca Channel of Chromaffin Cells. Int J Mol Sci 2021; 22:ijms22042175. [PMID: 33671654 PMCID: PMC7926978 DOI: 10.3390/ijms22042175] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/10/2021] [Accepted: 02/18/2021] [Indexed: 12/18/2022] Open
Abstract
Sphingosine-1-phosphate (S1P), is a signaling sphingolipid which acts as a bioactive lipid mediator. We assessed whether S1P had multiplex effects in regulating the large-conductance Ca2+-activated K+ channel (BKCa) in catecholamine-secreting chromaffin cells. Using multiple patch-clamp modes, Ca2+ imaging, and computational modeling, we evaluated the effects of S1P on the Ca2+-activated K+ currents (IK(Ca)) in bovine adrenal chromaffin cells and in a pheochromocytoma cell line (PC12). In outside-out patches, the open probability of BKCa channel was reduced with a mean-closed time increment, but without a conductance change in response to a low-concentration S1P (1 µM). The intracellular Ca2+ concentration (Cai) was elevated in response to a high-dose (10 µM) but not low-dose of S1P. The single-channel activity of BKCa was also enhanced by S1P (10 µM) in the cell-attached recording of chromaffin cells. In the whole-cell voltage-clamp, a low-dose S1P (1 µM) suppressed IK(Ca), whereas a high-dose S1P (10 µM) produced a biphasic response in the amplitude of IK(Ca), i.e., an initial decrease followed by a sustained increase. The S1P-induced IK(Ca) enhancement was abolished by BAPTA. Current-clamp studies showed that S1P (1 µM) increased the action potential (AP) firing. Simulation data revealed that the decreased BKCa conductance leads to increased AP firings in a modeling chromaffin cell. Over a similar dosage range, S1P (1 µM) inhibited IK(Ca) and the permissive role of S1P on the BKCa activity was also effectively observed in the PC12 cell system. The S1P-mediated IK(Ca) stimulation may result from the elevated Cai, whereas the inhibition of BKCa activity by S1P appears to be direct. By the differentiated tailoring BKCa channel function, S1P can modulate stimulus-secretion coupling in chromaffin cells.
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Ren J, Cheng Y, Wen X, Liu P, Zhao F, Xin F, Wang M, Huang H, Wang W. BK Ca channel participates in insulin-induced lipid deposition in adipocytes by increasing intracellular calcium. J Cell Physiol 2021; 236:5818-5831. [PMID: 33432604 DOI: 10.1002/jcp.30266] [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: 05/22/2020] [Revised: 12/22/2020] [Accepted: 12/24/2020] [Indexed: 12/21/2022]
Abstract
Storing energy in the form of triglyceride (TG) is one of the basic functions of adipose tissue. Large-conductance calcium-activated potassium channels (BKCa channels) are expressed in adipose tissue and adipocyte-specific BKCa deficiency resists obesity in mice, but the role of BKCa channels in lipid deposition and the underlying mechanisms have not been elucidated. In the present study, we generated BKCa knockout (KO) rats and performed a transcriptome analysis of adipose tissue. We found that the phosphoinositide 3-kinase (PI3K)-protein kinase B (Akt) signaling pathway, which is important for lipid deposition, exhibited the most notable reduction among various signaling pathways in BKCa KO rats compared to wild-type rats. Insulin-induced TG deposition, glucose uptake, and Akt (Ser473) phosphorylation were significantly reduced in cultured adipocytes differentiated from adipose-derived stem cells of BKCa KO rats. Furthermore, we found that the insulin-induced increase of intracellular calcium resulting from extracellular calcium influx was significantly impaired in BKCa KO adipocytes. Finally, insulin activated BKCa currents through PI3K, which was independent of Akt and intracellular calcium. The results of this study suggested that BKCa channels participate in the insulin signaling pathway and promote TG deposition by increasing extracellular calcium influx in adipocytes.
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Affiliation(s)
- Jie Ren
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Yuan Cheng
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Xinxin Wen
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Ping Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Lab for Cardiovascular Precision Medicine, Beijing, China
| | - Feng Zhao
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Fang Xin
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Lab for Cardiovascular Precision Medicine, Beijing, China
| | - Meili Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Metabolic Disorders Related Cardiovascular Diseases, Capital Medical University, Beijing, China
| | - Haixia Huang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Lab for Cardiovascular Precision Medicine, Beijing, China.,Beijing Key Laboratory of Metabolic Disorders Related Cardiovascular Diseases, Capital Medical University, Beijing, China
| | - Wei Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Lab for Cardiovascular Precision Medicine, Beijing, China
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Yang L, Fomina AF. Ca 2+ influx and clearance at hyperpolarized membrane potentials modulate spontaneous and stimulated exocytosis in neuroendocrine cells. Cell Calcium 2020; 87:102184. [PMID: 32151786 DOI: 10.1016/j.ceca.2020.102184] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 02/10/2020] [Accepted: 02/21/2020] [Indexed: 01/09/2023]
Abstract
Neuroendocrine adrenal chromaffin cells release neurohormones catecholamines in response to Ca2+ entry via voltage-gated Ca2+ channels (VGCCs). Adrenal chromaffin cells also express non-voltage-gated channels, which may conduct Ca2+ at negative membrane potentials, whose role in regulation of exocytosis is poorly understood. We explored how modulation of Ca2+ influx at negative membrane potentials affects basal cytosolic Ca2+ concentration ([Ca2+]i) and exocytosis in metabolically intact voltage-clamped bovine adrenal chromaffin cells. We found that in these cells, Ca2+ entry at negative membrane potentials is balanced by Ca2+ extrusion by the Na+/Ca2+ exchanger and that this balance can be altered by membrane hyperpolarization or stimulation with an inflammatory hormone bradykinin. Membrane hyperpolarization or application of bradykinin augmented Ca2+-carrying current at negative membrane potentials, elevated basal [Ca2+]i, and facilitated synchronous exocytosis evoked by the small amounts of Ca2+ injected into the cell via VGCCs (up to 20 pC). Exocytotic responses evoked by the injections of the larger amounts of Ca2+ via VGCCs (> 20 pC) were suppressed by preceding hyperpolarization. In the absence of Ca2+ entry via VGCCs and Ca2+ extrusion via the Na+/Ca2+ exchanger, membrane hyperpolarization induced a significant elevation in [Ca2+]i and asynchronous exocytosis. Our results indicate that physiological interferences, such as membrane hyperpolarization and/or activation of non-voltage-gated Ca2+ channels, modulate basal [Ca2+]i and, consequently, segregation of exocytotic vesicles and their readiness to be released spontaneously and in response to Ca2+ entry via VGCCs. These mechanisms may play role in homeostatic plasticity of neuronal and endocrine cells.
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Affiliation(s)
- Lukun Yang
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, 95616, USA; Department of Anesthesiology, The 5th Affiliated Hospital of SUN YAT-SEN University, Zhuhai, 519000, China.
| | - Alla F Fomina
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, 95616, USA.
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Carbone E, Borges R, Eiden LE, García AG, Hernández‐Cruz A. Chromaffin Cells of the Adrenal Medulla: Physiology, Pharmacology, and Disease. Compr Physiol 2019; 9:1443-1502. [DOI: 10.1002/cphy.c190003] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Calorio C, Gavello D, Guarina L, Salio C, Sassoè-Pognetto M, Riganti C, Bianchi FT, Hofer NT, Tuluc P, Obermair GJ, Defilippi P, Balzac F, Turco E, Bett GC, Rasmusson RL, Carbone E. Impaired chromaffin cell excitability and exocytosis in autistic Timothy syndrome TS2-neo mouse rescued by L-type calcium channel blockers. J Physiol 2019; 597:1705-1733. [PMID: 30629744 DOI: 10.1113/jp277487] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 12/19/2018] [Indexed: 12/30/2022] Open
Abstract
KEY POINTS Tymothy syndrome (TS) is a multisystem disorder featuring cardiac arrhythmias, autism and adrenal gland dysfunction that originates from a de novo point mutation in the gene encoding the Cav1.2 (CACNA1C) L-type channel. To study the role of Cav1.2 channel signals in autism, the autistic TS2-neo mouse has been generated bearing the G406R point-mutation associated with TS type-2. Using heterozygous TS2-neo mice, we report that the G406R mutation reduces the rate of inactivation and shifts leftward the activation and inactivation of L-type channels, causing marked increase of resting Ca2+ influx ('window' Ca2+ current). The increased 'window current' causes marked reduction of NaV channel density, switches normal tonic firing to abnormal burst firing, reduces mitochondrial metabolism, induces cell swelling and decreases catecholamine release. Overnight incubations with nifedipine rescue NaV channel density, normal firing and the quantity of catecholamine released. We provide evidence that chromaffin cell malfunction derives from altered Cav1.2 channel gating. ABSTRACT L-type voltage-gated calcium (Cav1) channels have a key role in long-term synaptic plasticity, sensory transduction, muscle contraction and hormone release. A point mutation in the gene encoding Cav1.2 (CACNA1C) causes Tymothy syndrome (TS), a multisystem disorder featuring cardiac arrhythmias, autism spectrum disorder (ASD) and adrenal gland dysfunction. In the more severe type-2 form (TS2), the missense mutation G406R is on exon 8 coding for the IS6-helix of the Cav1.2 channel. The mutation causes reduced inactivation and induces autism. How this occurs and how Cav1.2 gating-changes alter cell excitability, neuronal firing and hormone release on a molecular basis is still largely unknown. Here, using the TS2-neo mouse model of TS we show that the G406R mutation altered excitability and reduced secretory activity in adrenal chromaffin cells (CCs). Specifically, the TS2 mutation reduced the rate of voltage-dependent inactivation and shifted leftward the activation and steady-state inactivation of L-type channels. This markedly increased the resting 'window' Ca2+ current that caused an increased percentage of CCs undergoing abnormal action potential (AP) burst firing, cell swelling, reduced mitochondrial metabolism and decreased catecholamine release. The increased 'window' Ca2+ current caused also decreased NaV channel density and increased steady-state inactivation, which contributed to the increased abnormal burst firing. Overnight incubation with the L-type channel blocker nifedipine rescued the normal AP firing of CCs, the density of functioning NaV channels and their steady-state inactivation. We provide evidence that CC malfunction derives from the altered Cav1.2 channel gating and that dihydropyridines are potential therapeutics for ASD.
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Affiliation(s)
- Chiara Calorio
- Department of Drug Science, NIS Centre, University of Torino, Torino, Italy
| | - Daniela Gavello
- Department of Drug Science, NIS Centre, University of Torino, Torino, Italy
| | - Laura Guarina
- Department of Drug Science, NIS Centre, University of Torino, Torino, Italy
| | - Chiara Salio
- Department of Veterinary Sciences, University of Torino, Torino, Italy
| | - Marco Sassoè-Pognetto
- Department of Neuroscience Rita Levi Montalcini, University of Torino, Torino, Italy
| | - Chiara Riganti
- Department of Oncology, University of Torino, Torino, Italy
| | | | - Nadja T Hofer
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Petronel Tuluc
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Gerald J Obermair
- Department of Physiology & Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Paola Defilippi
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Fiorella Balzac
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Emilia Turco
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Glenna C Bett
- Department of Physiology & Biophysics, State University of New York, Buffalo, NY, USA
| | - Randall L Rasmusson
- Department of Physiology & Biophysics, State University of New York, Buffalo, NY, USA
| | - Emilio Carbone
- Department of Drug Science, NIS Centre, University of Torino, Torino, Italy
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Roles of Na +, Ca 2+, and K + channels in the generation of repetitive firing and rhythmic bursting in adrenal chromaffin cells. Pflugers Arch 2017; 470:39-52. [PMID: 28776261 DOI: 10.1007/s00424-017-2048-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 07/23/2017] [Indexed: 12/30/2022]
Abstract
Adrenal chromaffin cells (CCs) are the main source of circulating catecholamines (CAs) that regulate the body response to stress. Release of CAs is controlled neurogenically by the activity of preganglionic sympathetic neurons through trains of action potentials (APs). APs in CCs are generated by robust depolarization following the activation of nicotinic and muscarinic receptors that are highly expressed in CCs. Bovine, rat, mouse, and human CCs also express a composite array of Na+, K+, and Ca2+ channels that regulate the resting potential, shape the APs, and set the frequency of AP trains. AP trains of increasing frequency induce enhanced release of CAs. If the primary role of CCs is simply to relay preganglionic nerve commands to CA secretion, why should they express such a diverse set of ion channels? An answer to this comes from recent observations that, like in neurons, CCs undergo complex firing patterns of APs suggesting the existence of an intrinsic CC excitability (non-neurogenically controlled). Recent work has shown that CCs undergo occasional or persistent burst firing elicited by altered physiological conditions or deletion of pore-regulating auxiliary subunits. In this review, we aim to give a rationale to the role of the many ion channel types regulating CC excitability. We will first describe their functional properties and then analyze how they contribute to pacemaking, AP shape, and burst waveforms. We will also furnish clear indications on missing ion conductances that may be involved in pacemaking and highlight the contribution of the crucial channels involved in burst firing.
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Guarina L, Vandael DHF, Carabelli V, Carbone E. Low pH o boosts burst firing and catecholamine release by blocking TASK-1 and BK channels while preserving Cav1 channels in mouse chromaffin cells. J Physiol 2017; 595:2587-2609. [PMID: 28026020 DOI: 10.1113/jp273735] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 12/07/2016] [Indexed: 12/19/2022] Open
Abstract
KEY POINTS Mouse chromaffin cells (MCCs) generate spontaneous burst-firing that causes large increases of Ca2+ -dependent catecholamine release, and is thus a key mechanism for regulating the functions of MCCs. With the aim to uncover a physiological role for burst-firing we investigated the effects of acidosis on MCC activity. Lowering the extracellular pH (pHo ) from 7.4 to 6.6 induces cell depolarizations of 10-15 mV that generate bursts of ∼330 ms at 1-2 Hz and a 7.4-fold increase of cumulative catecholamine-release. Burst-firing originates from the inhibition of the pH-sensitive TASK-1-channels and a 60% reduction of BK-channel conductance at pHo 6.6. Blockers of the two channels (A1899 and paxilline) mimic the effects of pHo 6.6, and this is reverted by the Cav1 channel blocker nifedipine. MCCs act as pH-sensors. At low pHo , they depolarize, undergo burst-firing and increase catecholamine-secretion, generating an effective physiological response that may compensate for the acute acidosis and hyperkalaemia generated during heavy exercise and muscle fatigue. ABSTRACT Mouse chromaffin cells (MCCs) generate action potential (AP) firing that regulates the Ca2+ -dependent release of catecholamines (CAs). Recent findings indicate that MCCs possess a variety of spontaneous firing modes that span from the common 'tonic-irregular' to the less frequent 'burst' firing. This latter is evident in a small fraction of MCCs but occurs regularly when Nav1.3/1.7 channels are made less available or when the Slo1β2-subunit responsible for BK channel inactivation is deleted. Burst firing causes large increases of Ca2+ -entry and potentiates CA release by ∼3.5-fold and thus may be a key mechanism for regulating MCC function. With the aim to uncover a physiological role for burst-firing we investigated the effects of acidosis on MCC activity. Lowering the extracellular pH (pHo ) from 7.4 to 7.0 and 6.6 induces cell depolarizations of 10-15 mV that generate repeated bursts. Bursts at pHo 6.6 lasted ∼330 ms, occurred at 1-2 Hz and caused an ∼7-fold increase of CA cumulative release. Burst firing originates from the inhibition of the pH-sensitive TASK-1/TASK-3 channels and from a 40% BK channel conductance reduction at pHo 7.0. The same pHo had little or no effect on Nav, Cav, Kv and SK channels that support AP firing in MCCs. Burst firing of pHo 6.6 could be mimicked by mixtures of the TASK-1 blocker A1899 (300 nm) and BK blocker paxilline (300 nm) and could be prevented by blocking L-type channels by adding 3 μm nifedipine. Mixtures of the two blockers raised cumulative CA-secretion even more than low pHo (∼12-fold), showing that the action of protons on vesicle release is mainly a result of the ionic conductance changes that increase Ca2+ -entry during bursts. Our data provide direct evidence suggesting that MCCs respond to low pHo with sustained depolarization, burst firing and enhanced CA-secretion, thus mimicking the physiological response of CCs to acute acidosis and hyperkalaemia generated during heavy exercise and muscle fatigue.
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Affiliation(s)
- Laura Guarina
- Department of Drug Science, Laboratory of Cellular and Molecular Neuroscience, NIS Centre, CNISM Unit, Torino, Italy
| | - David H F Vandael
- Department of Drug Science, Laboratory of Cellular and Molecular Neuroscience, NIS Centre, CNISM Unit, Torino, Italy.,Present address: Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg, Austria
| | - Valentina Carabelli
- Department of Drug Science, Laboratory of Cellular and Molecular Neuroscience, NIS Centre, CNISM Unit, Torino, Italy
| | - Emilio Carbone
- Department of Drug Science, Laboratory of Cellular and Molecular Neuroscience, NIS Centre, CNISM Unit, Torino, Italy
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Illison J, Tian L, McClafferty H, Werno M, Chamberlain LH, Leiss V, Sassmann A, Offermanns S, Ruth P, Shipston MJ, Lukowski R. Obesogenic and Diabetogenic Effects of High-Calorie Nutrition Require Adipocyte BK Channels. Diabetes 2016; 65:3621-3635. [PMID: 27605626 DOI: 10.2337/db16-0245] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 08/16/2016] [Indexed: 11/13/2022]
Abstract
Elevated adipose tissue expression of the Ca2+- and voltage-activated K+ (BK) channel was identified in morbidly obese men carrying a BK gene variant, supporting the hypothesis that K+ channels affect the metabolic responses of fat cells to nutrients. To establish the role of endogenous BKs in fat cell maturation, storage of excess dietary fat, and body weight (BW) gain, we studied a gene-targeted mouse model with global ablation of the BK channel (BKL1/L1) and adipocyte-specific BK-deficient (adipoqBKL1/L2) mice. Global BK deficiency afforded protection from BW gain and excessive fat accumulation induced by a high-fat diet (HFD). Expansion of white adipose tissue-derived epididymal BKL1/L1 preadipocytes and their differentiation to lipid-filled mature adipocytes in vitro, however, were improved. Moreover, BW gain and total fat masses of usually superobese ob/ob mice were significantly attenuated in the absence of BK, together supporting a central or peripheral role for BKs in the regulatory system that controls adipose tissue and weight. Accordingly, HFD-fed adipoqBKL1/L2 mutant mice presented with a reduced total BW and overall body fat mass, smaller adipocytes, and reduced leptin levels. Protection from pathological weight gain in the absence of adipocyte BKs was beneficial for glucose handling and related to an increase in body core temperature as a result of higher levels of uncoupling protein 1 and a low abundance of the proinflammatory interleukin-6, a common risk factor for diabetes and metabolic abnormalities. This suggests that adipocyte BK activity is at least partially responsible for excessive BW gain under high-calorie conditions, suggesting that BK channels are promising drug targets for pharmacotherapy of metabolic disorders and obesity.
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Affiliation(s)
- Julia Illison
- Pharmakologie, Toxikologie und Klinische Pharmazie, Institut für Pharmazie, Tübingen, Germany
| | - Lijun Tian
- Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, U.K
| | - Heather McClafferty
- Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, U.K
| | - Martin Werno
- Strathclyde Institute of Pharmacy and Biomedical Sciences, Strathclyde University, Glasgow, U.K
| | - Luke H Chamberlain
- Strathclyde Institute of Pharmacy and Biomedical Sciences, Strathclyde University, Glasgow, U.K
| | - Veronika Leiss
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, University Hospital Tübingen, Tübingen, Germany
| | - Antonia Sassmann
- Department of Pharmacology, Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Stefan Offermanns
- Department of Pharmacology, Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Peter Ruth
- Pharmakologie, Toxikologie und Klinische Pharmazie, Institut für Pharmazie, Tübingen, Germany
| | - Michael J Shipston
- Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, U.K
| | - Robert Lukowski
- Pharmakologie, Toxikologie und Klinische Pharmazie, Institut für Pharmazie, Tübingen, Germany
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Gavello D, Carbone E, Carabelli V. Leptin-mediated ion channel regulation: PI3K pathways, physiological role, and therapeutic potential. Channels (Austin) 2016; 10:282-96. [PMID: 27018500 DOI: 10.1080/19336950.2016.1164373] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Leptin is produced by adipose tissue and identified as a "satiety signal," informing the brain when the body has consumed enough food. Specific areas of the hypothalamus express leptin receptors (LEPRs) and are the primary site of leptin action for body weight regulation. In response to leptin, appetite is suppressed and energy expenditure allowed. Beside this hypothalamic action, leptin targets other brain areas in addition to neuroendocrine cells. LEPRs are expressed also in the hippocampus, neocortex, cerebellum, substantia nigra, pancreatic β-cells, and chromaffin cells of the adrenal gland. It is intriguing how leptin is able to activate different ionic conductances, thus affecting excitability, synaptic plasticity and neurotransmitter release, depending on the target cell. Most of the intracellular pathways activated by leptin and directed to ion channels involve PI3K, which in turn phosphorylates different downstream substrates, although parallel pathways involve AMPK and MAPK. In this review we will describe the effects of leptin on BK, KATP, KV, CaV, TRPC, NMDAR and AMPAR channels and clarify the landscape of pathways involved. Given the ability of leptin to influence neuronal excitability and synaptic plasticity by modulating ion channels activity, we also provide a short overview of the growing potentiality of leptin as therapeutic agent for treating neurological disorders.
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Affiliation(s)
- Daniela Gavello
- a Department of Drug Science , Lab of Cellular Physiology and Molecular Neuroscience, NIS Center of Excellence, University of Torino , Torino , Italy
| | - Emilio Carbone
- a Department of Drug Science , Lab of Cellular Physiology and Molecular Neuroscience, NIS Center of Excellence, University of Torino , Torino , Italy
| | - Valentina Carabelli
- a Department of Drug Science , Lab of Cellular Physiology and Molecular Neuroscience, NIS Center of Excellence, University of Torino , Torino , Italy
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