1
|
Humbert A, Lefebvre R, Nawrot M, Caussy C, Rieusset J. Calcium signalling in hepatic metabolism: Health and diseases. Cell Calcium 2023; 114:102780. [PMID: 37506596 DOI: 10.1016/j.ceca.2023.102780] [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: 02/28/2023] [Revised: 07/06/2023] [Accepted: 07/07/2023] [Indexed: 07/30/2023]
Abstract
The flexibility between the wide array of hepatic functions relies on calcium (Ca2+) signalling. Indeed, Ca2+ is implicated in the control of many intracellular functions as well as intercellular communication. Thus, hepatocytes adapt their Ca2+ signalling depending on their nutritional and hormonal environment, leading to opposite cellular functions, such as glucose storage or synthesis. Interestingly, hepatic metabolic diseases, such as obesity, type 2 diabetes and non-alcoholic fatty liver diseases, are associated with impaired Ca2+ signalling. Here, we present the hepatocytes' toolkit for Ca2+ signalling, complete with regulation systems and signalling pathways activated by nutrients and hormones. We further discuss the current knowledge on the molecular mechanisms leading to alterations of Ca2+ signalling in hepatic metabolic diseases, and review the literature on the clinical impact of Ca2+-targeting therapeutics.
Collapse
Affiliation(s)
- Alexandre Humbert
- Laboratoire CarMeN, INSERM U-1060, INRAE U-1397, Université Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, France
| | - Rémy Lefebvre
- Laboratoire CarMeN, INSERM U-1060, INRAE U-1397, Université Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, France
| | - Margaux Nawrot
- Laboratoire CarMeN, INSERM U-1060, INRAE U-1397, Université Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, France
| | - Cyrielle Caussy
- Laboratoire CarMeN, INSERM U-1060, INRAE U-1397, Université Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, France; Département Endocrinologie, Diabète et Nutrition, Hospices Civils de Lyon, Hôpital Lyon Sud, Pierre-Bénite, France
| | - Jennifer Rieusset
- Laboratoire CarMeN, INSERM U-1060, INRAE U-1397, Université Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, France.
| |
Collapse
|
2
|
Rodgers RL. Glucagon, cyclic AMP, and hepatic glucose mobilization: A half‐century of uncertainty. Physiol Rep 2022; 10:e15263. [PMID: 35569125 PMCID: PMC9107925 DOI: 10.14814/phy2.15263] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 12/14/2022] Open
Abstract
For at least 50 years, the prevailing view has been that the adenylate cyclase (AC)/cyclic AMP (cAMP)/protein kinase A pathway is the predominant signal mediating the hepatic glucose‐mobilizing actions of glucagon. A wealth of evidence, however, supports the alternative, that the operative signal most of the time is the phospholipase C (PLC)/inositol‐phosphate (IP3)/calcium/calmodulin pathway. The evidence can be summarized as follows: (1) The consensus threshold glucagon concentration for activating AC ex vivo is 100 pM, but the statistical hepatic portal plasma glucagon concentration range, measured by RIA, is between 28 and 60 pM; (2) Within that physiological concentration range, glucagon stimulates the PLC/IP3 pathway and robustly increases glucose output without affecting the AC/cAMP pathway; (3) Activation of a latent, amplified AC/cAMP pathway at concentrations below 60 pM is very unlikely; and (4) Activation of the PLC/IP3 pathway at physiological concentrations produces intracellular effects that are similar to those produced by activation of the AC/cAMP pathway at concentrations above 100 pM, including elevated intracellular calcium and altered activities and expressions of key enzymes involved in glycogenolysis, gluconeogenesis, and glycogen synthesis. Under metabolically stressful conditions, as in the early neonate or exercising adult, plasma glucagon concentrations often exceed 100 pM, recruiting the AC/cAMP pathway and enhancing the activation of PLC/IP3 pathway to boost glucose output, adaptively meeting the elevated systemic glucose demand. Whether the AC/cAMP pathway is consistently activated in starvation or diabetes is not clear. Because the importance of glucagon in the pathogenesis of diabetes is becoming increasingly evident, it is even more urgent now to resolve lingering uncertainties and definitively establish glucagon’s true mechanism of glycemia regulation in health and disease.
Collapse
Affiliation(s)
- Robert L. Rodgers
- Department of Biomedical and Pharmaceutical Sciences College of Pharmacy University of Rhode Island Kingston Rhode Island USA
| |
Collapse
|
3
|
Bartlett PJ, Cloete I, Sneyd J, Thomas AP. IP 3-Dependent Ca 2+ Oscillations Switch into a Dual Oscillator Mechanism in the Presence of PLC-Linked Hormones. iScience 2020; 23:101062. [PMID: 32353764 PMCID: PMC7191650 DOI: 10.1016/j.isci.2020.101062] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 12/11/2019] [Accepted: 04/09/2020] [Indexed: 11/28/2022] Open
Abstract
Ca2+ oscillations that depend on inositol-1,4,5-trisphosphate (IP3) have been ascribed to biphasic Ca2+ regulation of the IP3 receptor (IP3R) or feedback mechanisms controlling IP3 levels in different cell types. IP3 uncaging in hepatocytes elicits Ca2+ transients that are often localized at the subcellular level and increase in magnitude with stimulus strength. However, this does not reproduce the broad baseline-separated global Ca2+ oscillations elicited by vasopressin. Addition of hormone to cells activated by IP3 uncaging initiates a qualitative transition from high-frequency spatially disorganized Ca2+ transients, to low-frequency, oscillatory Ca2+ waves that propagate throughout the cell. A mathematical model with dual coupled oscillators that integrates Ca2+-induced Ca2+ release at the IP3R and mutual feedback mechanisms of cross-coupling between Ca2+ and IP3 reproduces this behavior. Thus, multiple Ca2+ oscillation modes can coexist in the same cell, and hormonal stimulation can switch from the simpler to the more complex to yield robust signaling.
Collapse
Affiliation(s)
- Paula J Bartlett
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Ielyaas Cloete
- Department of Mathematics, The University of Auckland, Auckland, New Zealand
| | - James Sneyd
- Department of Mathematics, The University of Auckland, Auckland, New Zealand
| | - Andrew P Thomas
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ 07103, USA.
| |
Collapse
|
4
|
Lock JT, Smith IF, Parker I. Spatial-temporal patterning of Ca 2+ signals by the subcellular distribution of IP 3 and IP 3 receptors. Semin Cell Dev Biol 2019; 94:3-10. [PMID: 30703557 DOI: 10.1016/j.semcdb.2019.01.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 01/17/2019] [Accepted: 01/22/2019] [Indexed: 12/25/2022]
Abstract
The patterning of cytosolic Ca2+ signals in space and time underlies their ubiquitous ability to specifically regulate numerous cellular processes. Signals mediated by liberation of Ca2+ sequestered in the endoplasmic reticulum (ER) through inositol trisphosphate receptor (IP3R) channels constitute a hierarchy of events; ranging from openings of individual IP3 channels, through the concerted openings of several clustered IP3Rs to generate local Ca2+ puffs, to global Ca2+ waves and oscillations that engulf the entire cell. Here, we review recent progress in elucidating how this hierarchy is shaped by an interplay between the functional gating properties of IP3Rs and their spatial distribution within the cell. We focus in particular on the subset of IP3Rs that are organized in stationary clusters and are endowed with the ability to preferentially liberate Ca2+.
Collapse
Affiliation(s)
- Jeffrey T Lock
- Department of Neurobiology & Behavior, UC Irvine, Irvine, CA, USA.
| | - Ian F Smith
- Department of Neurobiology & Behavior, UC Irvine, Irvine, CA, USA
| | - Ian Parker
- Department of Neurobiology & Behavior, UC Irvine, Irvine, CA, USA; Department of Physiology & Biophysics, UC Irvine, Irvine, CA, USA
| |
Collapse
|
5
|
Bartlett PJ, Antony AN, Agarwal A, Hilly M, Prince VL, Combettes L, Hoek JB, Gaspers LD. Chronic alcohol feeding potentiates hormone-induced calcium signalling in hepatocytes. J Physiol 2017; 595:3143-3164. [PMID: 28220501 DOI: 10.1113/jp273891] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 01/26/2017] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Chronic alcohol consumption causes a spectrum of liver diseases, but the pathogenic mechanisms driving the onset and progression of disease are not clearly defined. We show that chronic alcohol feeding sensitizes rat hepatocytes to Ca2+ -mobilizing hormones resulting in a leftward shift in the concentration-response relationship and the transition from oscillatory to more sustained and prolonged Ca2+ increases. Our data demonstrate that alcohol-dependent adaptation in the Ca2+ signalling pathway occurs at the level of hormone-induced inositol 1,4,5 trisphosphate (IP3 ) production and does not involve changes in the sensitivity of the IP3 receptor or size of internal Ca2+ stores. We suggest that prolonged and aberrant hormone-evoked Ca2+ increases may stimulate the production of mitochondrial reactive oxygen species and contribute to alcohol-induced hepatocyte injury. ABSTRACT: 'Adaptive' responses of the liver to chronic alcohol consumption may underlie the development of cell and tissue injury. Alcohol administration can perturb multiple signalling pathways including phosphoinositide-dependent cytosolic calcium ([Ca2+ ]i ) increases, which can adversely affect mitochondrial Ca2+ levels, reactive oxygen species production and energy metabolism. Our data indicate that chronic alcohol feeding induces a leftward shift in the dose-response for Ca2+ -mobilizing hormones resulting in more sustained and prolonged [Ca2+ ]i increases in both cultured hepatocytes and hepatocytes within the intact perfused liver. Ca2+ increases were initiated at lower hormone concentrations, and intercellular calcium wave propagation rates were faster in alcoholics compared to controls. Acute alcohol treatment (25 mm) completely inhibited hormone-induced calcium increases in control livers, but not after chronic alcohol-feeding, suggesting desensitization to the inhibitory actions of ethanol. Hormone-induced inositol 1,4,5 trisphosphate (IP3 ) accumulation and phospholipase C (PLC) activity were significantly potentiated in hepatocytes from alcohol-fed rats compared to controls. Removal of extracellular calcium, or chelation of intracellular calcium did not normalize the differences in hormone-stimulated PLC activity, indicating calcium-dependent PLCs are not upregulated by alcohol. We propose that the liver 'adapts' to chronic alcohol exposure by increasing hormone-dependent IP3 formation, leading to aberrant calcium increases, which may contribute to hepatocyte injury.
Collapse
Affiliation(s)
- Paula J Bartlett
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Anil Noronha Antony
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Amit Agarwal
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Mauricette Hilly
- INSERM UMR-S 757, Université de Paris-Sud, bât 443, 91405, Orsay, France
| | - Victoria L Prince
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Laurent Combettes
- INSERM UMR-S 757, Université de Paris-Sud, bât 443, 91405, Orsay, France
| | - Jan B Hoek
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Lawrence D Gaspers
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| |
Collapse
|
6
|
Feriod CN, Oliveira AG, Guerra MT, Nguyen L, Richards KM, Jurczak MJ, Ruan HB, Camporez JP, Yang X, Shulman GI, Bennett AM, Nathanson MH, Ehrlich BE. Hepatic Inositol 1,4,5 Trisphosphate Receptor Type 1 Mediates Fatty Liver. Hepatol Commun 2016; 1:23-35. [PMID: 28966992 PMCID: PMC5613674 DOI: 10.1002/hep4.1012] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Fatty liver is the most common type of liver disease, affecting nearly one third of the US population and more than half a billion people worldwide. Abnormalities in ER calcium handling and mitochondrial function each have been implicated in abnormal lipid droplet formation. Here we show that the type 1 isoform of the inositol 1,4,5-trisphosphate receptor (InsP3R1) specifically links ER calcium release to mitochondrial calcium signaling and lipid droplet formation in hepatocytes. Moreover, liver-specific InsP3R1 knockout mice have impaired mitochondrial calcium signaling, decreased hepatic triglycerides, reduced lipid droplet formation and are resistant to development of fatty liver. Patients with non-alcoholic steatohepatitis, the most malignant form of fatty liver, have increased hepatic expression of InsP3R1 and the extent of ER-mitochondrial co-localization correlates with the degree of steatosis in human liver biopsies. CONCLUSION InsP3R1 plays a central role in lipid droplet formation in hepatocytes and the data suggest that it is involved in the development of human fatty liver disease.
Collapse
Affiliation(s)
- Colleen N Feriod
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, CT 06520.,Department of Pharmacology, Yale University School of Medicine New Haven, CT 06520
| | - Andre Gustavo Oliveira
- Section of Digestive Diseases, Internal Medicine, Yale University School of Medicine New Haven, CT 06520
| | - Mateus T Guerra
- Section of Digestive Diseases, Internal Medicine, Yale University School of Medicine New Haven, CT 06520
| | - Lily Nguyen
- Department of Pharmacology, Yale University School of Medicine New Haven, CT 06520
| | | | - Michael J Jurczak
- Department of Internal Medicine, Yale University School of Medicine New Haven, CT 06520
| | - Hai-Bin Ruan
- Department of Comparative Medicine, Yale University School of Medicine New Haven, CT 06520.,Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine New Haven, CT 06520
| | - Joao Paulo Camporez
- Department of Internal Medicine, Yale University School of Medicine New Haven, CT 06520
| | - Xiaoyong Yang
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, CT 06520.,Department of Comparative Medicine, Yale University School of Medicine New Haven, CT 06520.,Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine New Haven, CT 06520
| | - Gerald I Shulman
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, CT 06520.,Department of Internal Medicine, Yale University School of Medicine New Haven, CT 06520.,Howard Hughes Medical Institute, Yale University School of Medicine New Haven, CT 06520
| | - Anton M Bennett
- Department of Pharmacology, Yale University School of Medicine New Haven, CT 06520.,Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine New Haven, CT 06520
| | - Michael H Nathanson
- Section of Digestive Diseases, Internal Medicine, Yale University School of Medicine New Haven, CT 06520
| | - Barbara E Ehrlich
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, CT 06520.,Department of Pharmacology, Yale University School of Medicine New Haven, CT 06520
| |
Collapse
|
7
|
Weerachayaphorn J, Amaya MJ, Spirli C, Chansela P, Mitchell KA, Ananthanarayanan M, Nathanson MH. Nuclear Factor, Erythroid 2-Like 2 Regulates Expression of Type 3 Inositol 1,4,5-Trisphosphate Receptor and Calcium Signaling in Cholangiocytes. Gastroenterology 2015; 149:211-222.e10. [PMID: 25796361 PMCID: PMC4478166 DOI: 10.1053/j.gastro.2015.03.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 02/27/2015] [Accepted: 03/13/2015] [Indexed: 12/17/2022]
Abstract
BACKGROUND & AIMS Most cholestatic disorders are caused by defects in cholangiocytes. The type 3 isoform of the inositol 1,4,5-trisphosphate receptor (ITPR3) is the most abundant intracellular calcium release channel in cholangiocytes. ITPR3 is required for bicarbonate secretion by bile ducts, and its expression is reduced in intrahepatic bile ducts of patients with cholestatic disorders. We investigated whether the nuclear factor, erythroid 2-like 2 (NFE2L2 or NRF2), which is sensitive to oxidative stress, regulates expression of ITPR3. METHODS The activity of the ITPR3 promoter was measured in normal human cholangiocyte (NHC) cells and primary mouse cholangiocytes. Levels of ITPR3 protein and messenger RNA were examined by immunoblot and polymerase chain reaction analyses, respectively. ITPR3 activity was determined by measuring calcium signaling in normal human cholangiocyte cells and secretion in isolated bile duct units. Levels of NRF2 were measured in liver tissues from rats with cholestasis (induced by administration of α-napthylisothiocyanate) and from patients with biliary diseases. RESULTS We identified a musculo-aponeurotic fibrosarcoma recognition element in the promoter of ITPR3 that bound NRF2 directly in NHC cells and mouse cholangiocytes. Increasing binding of NRF2 at this site resulted in chromatin remodeling that reduced promoter activity. Mutant forms of the musculo-aponeurotic fibrosarcoma recognition element did not bind NRF2. Activation of NRF2 with quercetin or by oxidative stress reduced expression of ITPR3 and calcium signaling in NHC cells; quercetin also reduced secretion by bile duct units isolated from rats. Knockdown of NRF2 with small interfering RNAs restored expression and function of ITPR3 in NHC cells incubated with quercetin. Bile ducts from rats with cholestasis and patients with cholangiopathic disorders expressed higher levels of NRF2 and lower levels of ITPR3 than ducts from control rats or patients with other liver disorders. CONCLUSIONS The transcription factor NRF2 binds to the promoter of ITPR3 to inhibit its expression in cholangiocytes, leading to reduced calcium signaling and bile duct secretion. This could be a mechanism by which oxidative stress inhibits these processes and contributes to cholangiopathies.
Collapse
Affiliation(s)
- Jittima Weerachayaphorn
- Liver Center, Yale University School of Medicine, New Haven, Connecticut, USA,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Maria Jimena Amaya
- Liver Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Carlo Spirli
- Liver Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Piyachat Chansela
- Department of Anatomy, Phramongkutklao College of Medicine, Bangkok, Thailand
| | - Kisha A. Mitchell
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
| | | | - Michael H. Nathanson
- Liver Center, Yale University School of Medicine, New Haven, Connecticut, USA,Corresponding Author: Michael H. Nathanson MD., PhD., Department of Medicine, Section of Digestive Diseases, Yale University School of Medicine, 333 Cedar Street, TAC S241D, New Haven, CT, 06519 USA, Tel: (203)-785-7312, Fax: (203)-785-7273,
| |
Collapse
|
8
|
Oliveira AG, Andrade VA, Guimarães ES, Florentino RM, Sousa PA, Marques PE, Melo FM, Ortega MJ, Menezes GB, Leite MF. Calcium signalling from the type I inositol 1,4,5-trisphosphate receptor is required at early phase of liver regeneration. Liver Int 2015; 35:1162-71. [PMID: 24814243 DOI: 10.1111/liv.12587] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 04/30/2014] [Indexed: 12/15/2022]
Abstract
BACKGROUND & AIMS Liver regeneration is a multistage process that unfolds gradually, with different mediators acting at different stages of regeneration. Calcium (Ca(2+) ) signalling is essential for liver regeneration. In hepatocytes, Ca(2+) signalling results from the activation of inositol 1,4,5-trisphosphate receptors (InsP3 R) of which two of the three known isoforms are expressed (InsP3 R-I and InsP3 R-II). Here, we investigated the role of the InsP3 R-I-dependent Ca(2+) signals in hepatic proliferation during liver regeneration. METHODS Partial hepatectomy (HX) in combination with knockdown of InsP3 R-I (AdsiRNA-I) was used to evaluate the role of InsP3 R-I on liver regeneration and hepatocyte proliferation, as assessed by liver to body mass ratio, PCNA expression, immunoblots and measurements of intracellular Ca(2+) signalling. RESULTS AdsiRNA-I efficiently infected the liver as demonstrated by the expression of β-galactosidase throughout the liver lobules. Moreover, this construct selectively and efficiently reduced the expression of InsP3 R-I, as evaluated by immunoblots. Expression of AdsiRNA-I in liver decreased peak Ca(2+) amplitude induced by vasopressin in isolated hepatocytes 2 days after HX. Reduced InsP3 R-I expression prior to HX also delayed liver regeneration, as measured by liver to body weight ratio, and reduced hepatocyte proliferation, as evaluated by PCNA staining, at the same time point. At later stages of regeneration, control hepatocytes showed a decreased expression of InsP3 R, as well as reduced InsP3 R-mediated Ca(2+) signalling, events that did not affect liver growth. CONCLUSION Together, these results show that InsP3 R-I-dependent Ca(2+) signalling is an early triggering pathway required for liver regeneration.
Collapse
Affiliation(s)
- André G Oliveira
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Vervloessem T, Yule DI, Bultynck G, Parys JB. The type 2 inositol 1,4,5-trisphosphate receptor, emerging functions for an intriguing Ca²⁺-release channel. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:1992-2005. [PMID: 25499268 DOI: 10.1016/j.bbamcr.2014.12.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 12/19/2022]
Abstract
The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) type 2 (IP3R2) is an intracellular Ca²⁺-release channel located on the endoplasmic reticulum (ER). IP3R2 is characterized by a high sensitivity to both IP3 and ATP and is biphasically regulated by Ca²⁺. Furthermore, IP3R2 is modulated by various protein kinases. In addition to its regulation by protein kinase A, IP3R2 forms a complex with adenylate cyclase 6 and is directly regulated by cAMP. Finally, in the ER, IP3R2 is less mobile than the other IP3R isoforms, while its functional properties appear dominant in heterotetramers. These properties make the IP3R2 a Ca²⁺ channel with exquisite properties for setting up intracellular Ca²⁺ signals with unique characteristics. IP3R2 plays a crucial role in the function of secretory cell types (e.g. pancreatic acinar cells, hepatocytes, salivary gland, eccrine sweat gland). In cardiac myocytes, the role of IP3R2 appears more complex, because, together with IP3R1, it is needed for normal cardiogenesis, while its aberrant activity is implicated in cardiac hypertrophy and arrhythmias. Most importantly, its high sensitivity to IP3 makes IP3R2 a target for anti-apoptotic proteins (e.g. Bcl-2) in B-cell cancers. Disrupting IP3R/Bcl-2 interaction therefore leads in those cells to increased Ca²⁺ release and apoptosis. Intriguingly, IP3R2 is not only implicated in apoptosis but also in the induction of senescence, another tumour-suppressive mechanism. These results were the first to unravel the physiological and pathophysiological role of IP3R2 and we anticipate that further progress will soon be made in understanding the function of IP3R2 in various tissues and organs.
Collapse
Affiliation(s)
- Tamara Vervloessem
- KU Leuven, Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - David I Yule
- University of Rochester, Department of Pharmacology and Physiology, Rochester, NY, USA
| | - Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - Jan B Parys
- KU Leuven, Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Leuven, Belgium.
| |
Collapse
|
10
|
Apical localization of inositol 1,4,5-trisphosphate receptors is independent of extended synaptotagmins in hepatocytes. PLoS One 2014; 9:e114043. [PMID: 25437447 PMCID: PMC4250053 DOI: 10.1371/journal.pone.0114043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 11/03/2014] [Indexed: 12/12/2022] Open
Abstract
Extended synaptotagmins (E-Syts) are a recently identified family of proteins that tether the endoplasmic reticulum (ER) to the plasma membrane (PM) in part by conferring regulation of cytosolic calcium (Ca2+) at these contact sites (Cell, 2013). However, the mechanism by which E-Syts link this tethering to Ca2+ signaling is unknown. Ca2+ waves in polarized epithelia are initiated by inositol 1,4,5-trisphosphate receptors (InsP3Rs), and these waves begin in the apical region because InsP3Rs are targeted to the ER adjacent to the apical membrane. In this study we investigated whether E-Syts are responsible for this targeting. Primary rat hepatocytes were used as a model system, because a single InsP3R isoform (InsP3R-II) is tethered to the peri-apical ER in these cells. Additionally, it has been established in hepatocytes that the apical localization of InsP3Rs is responsible for Ca2+ waves and secretion and is disrupted in disease states in which secretion is impaired. We found that rat hepatocytes express two of the three identified E-Syts (E-Syt1 and E-Syt2). Individual or simultaneous siRNA knockdown of these proteins did not alter InsP3R-II expression levels, apical localization or average InsP3R-II cluster size. Moreover, apical secretion of the organic anion 5-chloromethylfluorescein diacetate (CMFDA) was not changed in cells lacking E-Syts but was reduced in cells in which cytosolic Ca2+ was buffered. These data provide evidence that E-Syts do not participate in the targeting of InsP3Rs to the apical region. Identifying tethers that bring InsP3Rs to the apical region remains an important question, since mis-targeting of InsP3Rs leads to impaired secretory activity.
Collapse
|
11
|
Bartlett PJ, Gaspers LD, Pierobon N, Thomas AP. Calcium-dependent regulation of glucose homeostasis in the liver. Cell Calcium 2014; 55:306-16. [PMID: 24630174 DOI: 10.1016/j.ceca.2014.02.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Revised: 02/07/2014] [Accepted: 02/08/2014] [Indexed: 02/09/2023]
Abstract
A major role of the liver is to integrate multiple signals to maintain normal blood glucose levels. The balance between glucose storage and mobilization is primarily regulated by the counteracting effects of insulin and glucagon. However, numerous signals converge in the liver to ensure energy demand matches the physiological status of the organism. Many circulating hormones regulate glycogenolysis, gluconeogenesis and mitochondrial metabolism by calcium-dependent signaling mechanisms that manifest as cytosolic Ca(2+) oscillations. Stimulus-strength is encoded in the Ca(2+) oscillation frequency, and also by the range of intercellular Ca(2+) wave propagation in the intact liver. In this article, we describe how Ca(2+) oscillations and waves can regulate glucose output and oxidative metabolism in the intact liver; how multiple stimuli are decoded though Ca(2+) signaling at the organ level, and the implications of Ca(2+) signal dysregulation in diseases such as metabolic syndrome and non-alcoholic fatty liver disease.
Collapse
Affiliation(s)
- Paula J Bartlett
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA.
| | - Lawrence D Gaspers
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Nicola Pierobon
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Andrew P Thomas
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| |
Collapse
|
12
|
Abstract
Intracellular free Ca(2+) ([Ca(2+)]i) is a highly versatile second messenger that regulates a wide range of functions in every type of cell and tissue. To achieve this versatility, the Ca(2+) signaling system operates in a variety of ways to regulate cellular processes that function over a wide dynamic range. This is particularly well exemplified for Ca(2+) signals in the liver, which modulate diverse and specialized functions such as bile secretion, glucose metabolism, cell proliferation, and apoptosis. These Ca(2+) signals are organized to control distinct cellular processes through tight spatial and temporal coordination of [Ca(2+)]i signals, both within and between cells. This article will review the machinery responsible for the formation of Ca(2+) signals in the liver, the types of subcellular, cellular, and intercellular signals that occur, the physiological role of Ca(2+) signaling in the liver, and the role of Ca(2+) signaling in liver disease.
Collapse
Affiliation(s)
- Maria Jimena Amaya
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | | |
Collapse
|
13
|
Amaral SS, Oliveira AG, Marques PE, Quintão JLD, Pires DA, Resende RR, Sousa BR, Melgaço JG, Pinto MA, Russo RC, Gomes AKC, Andrade LM, Zanin RF, Pereira RVS, Bonorino C, Soriani FM, Lima CX, Cara DC, Teixeira MM, Leite MF, Menezes GB. Altered responsiveness to extracellular ATP enhances acetaminophen hepatotoxicity. Cell Commun Signal 2013; 11:10. [PMID: 23384127 PMCID: PMC3608937 DOI: 10.1186/1478-811x-11-10] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 01/26/2013] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Adenosine triphosphate (ATP) is secreted from hepatocytes under physiological conditions and plays an important role in liver biology through the activation of P2 receptors. Conversely, higher extracellular ATP concentrations, as observed during necrosis, trigger inflammatory responses that contribute to the progression of liver injury. Impaired calcium (Ca2+) homeostasis is a hallmark of acetaminophen (APAP)-induced hepatotoxicity, and since ATP induces mobilization of the intracellular Ca2+ stocks, we evaluated if the release of ATP during APAP-induced necrosis could directly contribute to hepatocyte death. RESULTS APAP overdose resulted in liver necrosis, massive neutrophil infiltration and large non-perfused areas, as well as remote lung inflammation. In the liver, these effects were significantly abrogated after ATP metabolism by apyrase or P2X receptors blockage, but none of the treatments prevented remote lung inflammation, suggesting a confined local contribution of purinergic signaling into liver environment. In vitro, APAP administration to primary mouse hepatocytes and also HepG2 cells caused cell death in a dose-dependent manner. Interestingly, exposure of HepG2 cells to APAP elicited significant release of ATP to the supernatant in levels that were high enough to promote direct cytotoxicity to healthy primary hepatocytes or HepG2 cells. In agreement to our in vivo results, apyrase treatment or blockage of P2 receptors reduced APAP cytotoxicity. Likewise, ATP exposure caused significant higher intracellular Ca2+ signal in APAP-treated primary hepatocytes, which was reproduced in HepG2 cells. Quantitative real time PCR showed that APAP-challenged HepG2 cells expressed higher levels of several purinergic receptors, which may explain the hypersensitivity to extracellular ATP. This phenotype was confirmed in humans analyzing liver biopsies from patients diagnosed with acute hepatic failure. CONCLUSION We suggest that under pathological conditions, ATP may act not only an immune system activator, but also as a paracrine direct cytotoxic DAMP through the dysregulation of Ca2+ homeostasis.
Collapse
Affiliation(s)
- Sylvia S Amaral
- Laboratório de Imunobiofotônica, Departamento de Morfologia, UFMG, Belo Horizonte, MG, Brazil.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Orabi AI, Luo Y, Ahmad MU, Shah AU, Mannan Z, Wang D, Sarwar S, Muili KA, Shugrue C, Kolodecik TR, Singh VP, Lowe ME, Thrower E, Chen J, Husain SZ. IP3 receptor type 2 deficiency is associated with a secretory defect in the pancreatic acinar cell and an accumulation of zymogen granules. PLoS One 2012. [PMID: 23185258 PMCID: PMC3504040 DOI: 10.1371/journal.pone.0048465] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Acute pancreatitis is a painful, life-threatening disorder of the pancreas whose etiology is often multi-factorial. It is of great importance to understand the interplay between factors that predispose patients to develop the disease. One such factor is an excessive elevation in pancreatic acinar cell Ca2+. These aberrant Ca2+ elevations are triggered by release of Ca2+ from apical Ca2+ pools that are gated by the inositol 1,4,5-trisphosphate receptor (IP3R) types 2 and 3. In this study, we examined the role of IP3R type 2 (IP3R2) using mice deficient in this Ca2+ release channel (IP3R2−/−). Using live acinar cell Ca2+ imaging we found that loss of IP3R2 reduced the amplitude of the apical Ca2+ signal and caused a delay in its initiation. This was associated with a reduction in carbachol-stimulated amylase release and an accumulation of zymogen granules (ZGs). Specifically, there was a 2-fold increase in the number of ZGs (P<0.05) and an expansion of the ZG pool area within the cell. There was also a 1.6- and 2.6-fold increase in cellular amylase and trypsinogen, respectively. However, the mice did not have evidence of pancreatic injury at baseline, other than an elevated serum amylase level. Further, pancreatitis outcomes using a mild caerulein hyperstimulation model were similar between IP3R2−/− and wild type mice. In summary, IP3R2 modulates apical acinar cell Ca2+ signals and pancreatic enzyme secretion. IP3R-deficient acinar cells accumulate ZGs, but the mice do not succumb to pancreatic damage or worse pancreatitis outcomes.
Collapse
Affiliation(s)
- Abrahim I. Orabi
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Yuhuan Luo
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Mahwish U. Ahmad
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Ahsan U. Shah
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Zahir Mannan
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Dong Wang
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Sheharyar Sarwar
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Kamaldeen A. Muili
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Christine Shugrue
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Thomas R. Kolodecik
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Vijay P. Singh
- Department of Internal Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Mark E. Lowe
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Edwin Thrower
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Ju Chen
- Department of Molecular Pathology, University of California San Diego, San Diego, California, United States of America
| | - Sohail Z. Husain
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
| |
Collapse
|
15
|
Olson ML, Sandison ME, Chalmers S, McCarron JG. Microdomains of muscarinic acetylcholine and Ins(1,4,5)P₃ receptors create 'Ins(1,4,5)P₃ junctions' and sites of Ca²+ wave initiation in smooth muscle. J Cell Sci 2012; 125:5315-28. [PMID: 22946060 PMCID: PMC3561854 DOI: 10.1242/jcs.105163] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Increases in cytosolic Ca2+ concentration ([Ca2+]c) mediated by inositol (1,4,5)-trisphosphate [Ins(1,4,5)P3, hereafter InsP3] regulate activities that include division, contraction and cell death. InsP3-evoked Ca2+ release often begins at a single site, then regeneratively propagates through the cell as a Ca2+ wave. The Ca2+ wave consistently begins at the same site on successive activations. Here, we address the mechanisms that determine the Ca2+ wave initiation site in intestinal smooth muscle cells. Neither an increased sensitivity of InsP3 receptors (InsP3R) to InsP3 nor regional clustering of muscarinic receptors (mAChR3) or InsP3R1 explained the selection of an initiation site. However, examination of the overlap of mAChR3 and InsP3R1 localisation, by centre of mass analysis, revealed that there was a small percentage (∼10%) of sites that showed colocalisation. Indeed, the extent of colocalisation was greatest at the Ca2+ wave initiation site. The initiation site might arise from a selective delivery of InsP3 from mAChR3 activity to particular InsP3Rs to generate faster local [Ca2+]c increases at sites of colocalisation. In support of this hypothesis, a localised subthreshold ‘priming’ InsP3 concentration applied rapidly, but at regions distant from the initiation site, shifted the wave to the site of the priming. Conversely, when the Ca2+ rise at the initiation site was rapidly and selectively attenuated, the Ca2+ wave again shifted and initiated at a new site. These results indicate that Ca2+ waves initiate where there is a structural and functional coupling of mAChR3 and InsP3R1, which generates junctions in which InsP3 acts as a highly localised signal by being rapidly and selectively delivered to InsP3R1.
Collapse
Affiliation(s)
- Marnie L Olson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, The Arbuthnott Building, 161 Cathedral Street, Glasgow G4 0RE, UK
| | | | | | | |
Collapse
|
16
|
Gaspers LD, Mémin E, Thomas AP. Calcium-dependent physiologic and pathologic stimulus-metabolic response coupling in hepatocytes. Cell Calcium 2012; 52:93-102. [PMID: 22564906 DOI: 10.1016/j.ceca.2012.04.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 04/13/2012] [Accepted: 04/16/2012] [Indexed: 01/19/2023]
Abstract
A recurrent paradigm in calcium signaling is the coordination of the target response of the calcium signal with activation of metabolic energy production to support that response. This occurs in many tissues, including cardiac and skeletal muscle where contractile activity and ATP production are coordinately regulated by the frequency and amplitude of calcium transients, endocrine and exocrine cells that use calcium to drive the secretory process, and hepatocytes where the downstream targets of calcium include both catabolic and anabolic processes. The primary mechanism by which calcium enhances the capacity for energy production is through calcium-dependent stimulation of mitochondrial oxidative metabolism, achieved by increasing NADH production and respiratory chain flux. Although this enhances energy supply, it also has the potential for deleterious consequences resulting from increased generation of reactive oxygen species (ROS). The negative consequences of calcium-dependent mitochondrial activation can be ameliorated when the underlying cytosolic calcium signals occur as brief calcium spikes or oscillations, with signal strength encoded through the spike frequency (frequency modulation). Frequency modulation increases signal fidelity, and reduces pathological effects of calcium, including excess mitochondrial ROS production and apoptotic or necrotic outcomes. The present article reviews these issues using data obtained in hepatocytes under physiologic and pathologic conditions.
Collapse
Affiliation(s)
- Lawrence D Gaspers
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, Newark, NJ 07103, United States.
| | | | | |
Collapse
|
17
|
Abstract
After partial hepatectomy (PH) the initial mass of the organ is restored through a complex network of cellular interactions that orchestrate both proliferative and hepatoprotective signalling cascades. Among agonists involved in this network many of them drive Ca(2+) movements. During liver regeneration in the rat, hepatocyte cytosolic Ca(2+) signalling has been shown on the one hand to be deeply remodelled and on the other hand to enhance progression of hepatocytes through the cell cycle. Mechanisms through which cytosolic Ca(2+) signals impact on hepatocyte cell cycle early after PH are not completely understood, but at least they include regulation of immediate early gene transcription and ERK and CREB phosphorylation. In addition to cytosolic Ca(2+), there is also evidence that mitochondrial Ca(2+) and also nuclear Ca(2+) may be critical for the regulation of liver regeneration. Finally, Ca(2+) movements in hepatocytes, and possibly in other liver cells, not only impact hepatocyte progression in the cell cycle but more generally may regulate cellular homeostasis after PH.
Collapse
|
18
|
Fujimoto T, Machida T, Tsunoda T, Doi K, Ota T, Kuroki M, Shirasawa S. KRAS-induced actin-interacting protein regulates inositol 1,4,5-trisphosphate-receptor-mediated calcium release. Biochem Biophys Res Commun 2011; 408:214-7. [DOI: 10.1016/j.bbrc.2011.03.112] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 03/25/2011] [Indexed: 10/18/2022]
|
19
|
Inositol 1,4,5-trisphosphate receptor subtype-specific regulation of calcium oscillations. Neurochem Res 2011; 36:1175-85. [PMID: 21479917 PMCID: PMC3111726 DOI: 10.1007/s11064-011-0457-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/18/2011] [Indexed: 11/18/2022]
Abstract
Oscillatory fluctuations in the cytosolic concentration of free calcium ions (Ca2+) are considered a ubiquitous mechanism for controlling multiple cellular processes. Inositol 1,4,5-trisphosphate (IP3) receptors (IP3R) are intracellular Ca2+ release channels that mediate Ca2+ release from endoplasmic reticulum (ER) Ca2+ stores. The three IP3R subtypes described so far exhibit differential structural, biophysical, and biochemical properties. Subtype specific regulation of IP3R by the endogenous modulators IP3, Ca2+, protein kinases and associated proteins have been thoroughly examined. In this article we will review the contribution of each IP3R subtype in shaping cytosolic Ca2+ oscillations.
Collapse
|
20
|
Determination of the critical region of KRAS-induced actin-interacting protein for the interaction with inositol 1,4,5-trisphosphate receptor. Biochem Biophys Res Commun 2011; 408:282-6. [PMID: 21501587 DOI: 10.1016/j.bbrc.2011.04.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 04/03/2011] [Indexed: 11/23/2022]
Abstract
KRAS-induced actin-interacting protein (KRAP) was originally characterized as a filamentous-actin-interacting protein. We have recently found that KRAP is an associated molecule with inositol 1,4,5-trisphosphate receptor (IP(3)R) and is critical for the proper subcellular localization and function of IP(3)R. However, the molecular mechanisms underlying the regulation of IP(3)R by KRAP remain elusive. In this report, to determine the critical region of KRAP protein for the regulation of IP(3)R, we generate several mutants of KRAP and examine the association with IP(3)R using coimmunoprecipitation and confocal imaging assays. Coimmunoprecipitations using the deletion mutants reveal that amino-acid residues 1-218 but not 1-199 of KRAP interact with IP(3)R, indicating that the 19-length amino-acid residues (200-218) are essential for the association with IP(3)R. This critical region is highly conserved between human and mouse KRAP. Within the critical region, substitutions of two phenylalanine residues (Phe202/Phe203) in mouse KRAP to alanines result in failure of the association with IP(3)R, suggesting that the two consecutive phenylalanine residues are indispensable for the association. Moreover, the KRAP-knockdown stable HeLa cells exhibit the inappropriate subcellular localization of IP(3)R, in which exogenous expression of full-length of KRAP properly restores the subcellular localization of IP(3)R, but not the 1-218 or 1-236 mutant, indicating that the residual carboxyl-terminal region is also required for the proper subcellular localization of KRAP-IP(3)R complex. All these results provide insight into the understandings for the molecular mechanisms underlying the regulation of IP(3)R, and would reveal a potent strategy for the drug development targeting on IP(3)R.
Collapse
|
21
|
KRAS-induced actin-interacting protein is required for the proper localization of inositol 1,4,5-trisphosphate receptor in the epithelial cells. Biochem Biophys Res Commun 2011; 407:438-43. [PMID: 21420385 DOI: 10.1016/j.bbrc.2011.03.065] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Accepted: 03/14/2011] [Indexed: 11/23/2022]
Abstract
Three inositol 1,4,5-trisphosphate receptor (IP(3)R) subtypes are differentially expressed among tissues and function as the Ca(2+) release channel on specialized endoplasmic reticulum (ER) membranes. The proper subcellular localization of IP(3)R is crucial for its proper function, but this molecular mechanism is unclear. KRAS-induced actin-interacting protein (KRAP) was originally identified as a cancer-related molecule, and is involved in the regulation of whole-body energy homeostasis and pancreatic exocrine system. We herein identified IP(3)R as an associated molecule with KRAP in vivo, and the association was validated by the co-immunoprecipitation and confocal immunostaining studies in mouse tissues including liver and pancreas. The association of KRAP with IP(3)R was also observed in the human epithelial cell lines including HCT116, HeLa and HEK293 cells. Intriguingly, KRAP interacts with distinct subtypes of IP(3)R in a tissue-dependent manner, i.e. IP(3)R1 and IP(3)R2 in the liver and IP(3)R2 and IP(3)R3 in the pancreas. The NH(2)-terminal amino acid residues 1-610 of IP(3)R are critical for the association with KRAP and KRAP-IP(3)R complex resides in a specialized ER but not a typical reticular ER. Furthermore, the localization of particular IP(3)R subtypes in tissues from KRAP-deficient mice is obviously disturbed, i.e. IP(3)R1 and IP(3)R2 in the liver and IP(3)R2 and IP(3)R3 in the pancreas. These findings demonstrate that KRAP physically associates with IP(3)R and regulates the proper localization of IP(3)R in the epithelial cells in vivo and cultured cells, and might shed light on the Ca(2+) signaling underlying physiological cellular programs, cancer development and metabolism-related diseases.
Collapse
|
22
|
Fiedler MJ, Nathanson MH. The type I inositol 1,4,5-trisphosphate receptor interacts with protein 4.1N to mediate neurite formation through intracellular Ca waves. Neurosignals 2011; 19:75-85. [PMID: 21389686 PMCID: PMC3124450 DOI: 10.1159/000324507] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Accepted: 01/25/2011] [Indexed: 01/07/2023] Open
Abstract
Ca2+ waves are an important mechanism for encoding Ca2+ signaling information, but the molecular basis for wave formation and how this regulates neuronal function is not entirely understood. Using nerve growth factor-differentiated PC12 cells as a model system, we investigated the interaction between the type I inositol 1,4,5-trisphosphate receptor (IP3R1) and the cytoskeletal linker, protein 4.1N, to examine the relationship between Ca2+ wave formation and neurite development. This was examined using RNAi and overexpressed dominant negative binding regions of each protein. Confocal microscopy was used to monitor neurite formation and Ca2+ waves. Knockdown of IP3R1 or 4.1N attenuated neurite formation, as did binding regions of IP3R1 and 4.1N, which colocalized with endogenous 4.1N and IP3R1, respectively. Upon stimulation with the IP3-producing agonist carbachol, both RNAi and dominant negative molecules shifted signaling events from waves to homogeneous patterns of Ca2+ release. These findings provide evidence that IP3R1 localization, via protein 4.1N, is necessary for Ca2+ wave formation, which in turn mediates neurite formation.
Collapse
Affiliation(s)
- Michael J Fiedler
- Cell Biology Department, Yale University, New Haven, CT 06520-8019, USA
| | | |
Collapse
|
23
|
Jones L, Ma L, Castro J, Litjens T, Barritt G, Rychkov G. The predominant role of IP3 type 1 receptors in activation of store-operated Ca2+ entry in liver cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:745-51. [DOI: 10.1016/j.bbamem.2010.12.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Revised: 12/10/2010] [Accepted: 12/13/2010] [Indexed: 10/18/2022]
|
24
|
Shibao K, Fiedler MJ, Nagata J, Minagawa N, Hirata K, Nakayama Y, Iwakiri Y, Nathanson MH, Yamaguchi K. The type III inositol 1,4,5-trisphosphate receptor is associated with aggressiveness of colorectal carcinoma. Cell Calcium 2010; 48:315-23. [PMID: 21075448 PMCID: PMC3572849 DOI: 10.1016/j.ceca.2010.09.005] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 09/07/2010] [Accepted: 09/08/2010] [Indexed: 01/26/2023]
Abstract
The inositol 1,4,5-trisphosphate receptor (InsP3R) mediates Ca(2+) signaling in epithelia and regulates cellular functions such as secretion, apoptosis and cell proliferation. Loss of one or more InsP3R isoform has been implicated in disease processes such as cholestasis. Here we examined whether gain of expression of InsP3R isoforms also may be associated with development of disease. Expression of all three InsP3R isoforms was evaluated in tissue from colorectal carcinomas surgically resected from 116 patients. Type I and II InsP3Rs were seen in both normal colorectal mucosa and colorectal cancer, while type III InsP3R was observed only in colorectal cancer. Type III InsP3R expression in the advancing margins of tumors correlated with depth of invasion, lymph node metastasis, liver metastasis, and TNM stage. Heavier expression of type III InsP3R also was associated with decreased 5-year survival. shRNA knockdown of type III InsP3R in CACO-2 colon cancer cells enhanced apoptosis, while over-expression of the receptor decreased apoptosis. Thus, type III InsP3R becomes expressed in colon cancer, and its expression level is directly related to aggressiveness of the tumor, which may reflect inhibition of apoptosis by the receptor. These findings suggest a previously unrecognized role for Ca(2+) signaling via this InsP3R isoform in colon cancer.
Collapse
Affiliation(s)
- Kazunori Shibao
- Department of Surgery I, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Japan
| | - Michael J. Fiedler
- Digestive Diseases Section, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
| | - Jun Nagata
- Department of Surgery I, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Japan
| | - Noritaka Minagawa
- Department of Surgery I, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Japan
| | - Keiji Hirata
- Department of Nursing, International University of Health and Welfare, Fukuoka, Japan
| | - Yoshifumi Nakayama
- Department of Surgery I, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Japan
| | - Yasuko Iwakiri
- Digestive Diseases Section, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
| | - Michael H. Nathanson
- Digestive Diseases Section, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
| | - Koji Yamaguchi
- Department of Surgery I, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Japan
| |
Collapse
|
25
|
Casas M, Figueroa R, Jorquera G, Escobar M, Molgó J, Jaimovich E. IP(3)-dependent, post-tetanic calcium transients induced by electrostimulation of adult skeletal muscle fibers. ACTA ACUST UNITED AC 2010; 136:455-67. [PMID: 20837675 PMCID: PMC2947059 DOI: 10.1085/jgp.200910397] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Tetanic electrical stimulation induces two separate calcium signals in rat skeletal myotubes, a fast one, dependent on Cav 1.1 or dihydropyridine receptors (DHPRs) and ryanodine receptors and related to contraction, and a slow signal, dependent on DHPR and inositol trisphosphate receptors (IP3Rs) and related to transcriptional events. We searched for slow calcium signals in adult muscle fibers using isolated adult flexor digitorum brevis fibers from 5–7-wk-old mice, loaded with fluo-3. When stimulated with trains of 0.3-ms pulses at various frequencies, cells responded with a fast calcium signal associated with muscle contraction, followed by a slower signal similar to one previously described in cultured myotubes. Nifedipine inhibited the slow signal more effectively than the fast one, suggesting a role for DHPR in its onset. The IP3R inhibitors Xestospongin B or C (5 µM) also inhibited it. The amplitude of post-tetanic calcium transients depends on both tetanus frequency and duration, having a maximum at 10–20 Hz. At this stimulation frequency, an increase of the slow isoform of troponin I mRNA was detected, while the fast isoform of this gene was inhibited. All three IP3R isoforms were present in adult muscle. IP3R-1 was differentially expressed in different types of muscle fibers, being higher in a subset of fast-type fibers. Interestingly, isolated fibers from the slow soleus muscle did not reveal the slow calcium signal induced by electrical stimulus. These results support the idea that IP3R-dependent slow calcium signals may be characteristic of distinct types of muscle fibers and may participate in the activation of specific transcriptional programs of slow and fast phenotype.
Collapse
Affiliation(s)
- Mariana Casas
- Centro de Estudios Moleculares de la Célula, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | | | | | | | | | | |
Collapse
|
26
|
Costa RR, Varanda WA, Franci CR. A calcium-induced calcium release mechanism supports luteinizing hormone-induced testosterone secretion in mouse Leydig cells. Am J Physiol Cell Physiol 2010; 299:C316-23. [DOI: 10.1152/ajpcell.00521.2009] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Leydig cells are responsible for the synthesis and secretion of testosterone, processes controlled by luteinizing hormone (LH). Binding of LH to a G protein-coupled receptor in the plasma membrane results in an increase in cAMP and in intracellular Ca2+ concentration ([Ca2+]i). Here we show, using immunofluorescence, that Leydig cells express ryanodine receptors (RyRs) and inositol 1,4,5-trisphosphate receptors (IP3Rs). Measurements of intracellular calcium changes using the fluorescent calcium-sensitive dye fluo-3 and confocal microscopy show that both types of receptors are involved in a calcium-induced calcium release (CICR) mechanism, which amplifies the initial Ca2+ influx through plasma membrane T-type calcium channels (CaV3). The RyRs and IP3Rs are functional, as judged from both their activation by caffeine and IP3 and block by ryanodine and 2-aminoethoxydiphenyl borate (2-APB), respectively. RyRs are the principal players involved in the release of Ca2+ from the endoplasmic reticulum, as evidenced by the fact that global Ca2+ changes evoked by LH are readily blocked by 100 μM ryanodine but not by 2-APB or xestospongin C. Finally, steroid production by Leydig cells is inhibited by ryanodine but not by 2-APB. These results not only broaden our understanding of the role played by calcium in Leydig cells but also show, for the first time, that RyRs have an important role in determining testosterone secretion by the testis.
Collapse
Affiliation(s)
- Roberta Ribeiro Costa
- Department of Physiology, School of Medicine of Ribeirão Preto/University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Wamberto Antonio Varanda
- Department of Physiology, School of Medicine of Ribeirão Preto/University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Celso Rodrigues Franci
- Department of Physiology, School of Medicine of Ribeirão Preto/University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| |
Collapse
|
27
|
Cruz LN, Guerra MT, Kruglov E, Mennone A, Garcia CRS, Chen J, Nathanson MH. Regulation of multidrug resistance-associated protein 2 by calcium signaling in mouse liver. Hepatology 2010; 52:327-37. [PMID: 20578149 PMCID: PMC3025771 DOI: 10.1002/hep.23625] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
UNLABELLED Multidrug resistance associated protein 2 (Mrp2) is a canalicular transporter responsible for organic anion secretion into bile. Mrp2 activity is regulated by insertion into the plasma membrane; however, the factors that control this are not understood. Calcium (Ca(2+)) signaling regulates exocytosis of vesicles in most cell types, and the type II inositol 1,4,5-triphosphate receptor (InsP(3)R2) regulates Ca(2+) release in the canalicular region of hepatocytes. However, the role of InsP(3)R2 and of Ca(2+) signals in canalicular insertion and function of Mrp2 is not known. The aim of this study was to determine the role of InsP(3)R2-mediated Ca(2+) signals in targeting Mrp2 to the canalicular membrane. Livers, isolated hepatocytes, and hepatocytes in collagen sandwich culture from wild-type (WT) and InsP(3)R2 knockout (KO) mice were used for western blots, confocal immunofluorescence, and time-lapse imaging of Ca(2+) signals and of secretion of a fluorescent organic anion. Plasma membrane insertion of green fluorescent protein (GFP)-Mrp2 expressed in HepG2 cells was monitored by total internal reflection microscopy. InsP(3)R2 was concentrated in the canalicular region of WT mice but absent in InsP(3)R2 KO livers, whereas expression and localization of InsP(3)R1 was preserved, and InsP(3)R3 was absent from both WT and KO livers. Ca(2+) signals induced by either adenosine triphosphate (ATP) or vasopressin were impaired in hepatocytes lacking InsP(3)R2. Canalicular secretion of the organic anion 5-chloromethylfluorescein diacetate (CMFDA) was reduced in KO hepatocytes, as well as in WT hepatocytes treated with 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Moreover, the choleretic effect of tauroursodeoxycholic acid (TUDCA) was impaired in InsP(3)R2 KO mice. Finally, ATP increased GFP-Mrp2 fluorescence in the plasma membrane of HepG2 cells, and this also was reduced by BAPTA. CONCLUSION InsP(3)R2-mediated Ca(2+) signals enhance organic anion secretion into bile by targeting Mrp2 to the canalicular membrane.
Collapse
Affiliation(s)
- Laura N. Cruz
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT,Department of Parasitology, University of Saão Paulo, Saão Paulo, Brazil
| | - Mateus T. Guerra
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT,Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Emma Kruglov
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Albert Mennone
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | | | - Ju Chen
- Department of Medicine, University of California, San Diego, CA
| | - Michael H. Nathanson
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| |
Collapse
|
28
|
Sartorello R, Amaya MJ, Nathanson MH, Garcia CRS. The plasmodium receptor for activated C kinase protein inhibits Ca(2+) signaling in mammalian cells. Biochem Biophys Res Commun 2009; 389:586-92. [PMID: 19748487 DOI: 10.1016/j.bbrc.2009.09.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Accepted: 09/04/2009] [Indexed: 11/28/2022]
Abstract
Plasmodium falciparum, the most lethal malarial parasite, expresses an ortholog for the protein kinase C (PKC) activator RACK1. However, PKC has not been identified in this parasite, and the mammalian RACK1 can interact with the inositol 1,4,5-trisphosphate receptor (InsP3R). Therefore we investigated whether the Plasmodium ortholog PfRACK also can affect InsP3R-mediated Ca(2+) signaling in mammalian cells. GFP-tagged PfRACK and endogenous RACK1 were expressed in a similar distribution within cells. PfRACK inhibited agonist-induced Ca(2+) signals in cells expressing each isoform of the InsP3R, and this effect persisted when expression of endogenous RACK1 was reduced by siRNA. PfRACK also inhibited Ca(2+) signals induced by photorelease of caged InsP3. These findings provide evidence that PfRACK directly inhibits InsP3-mediated Ca(2+) signaling in mammalian cells. Interference with host cell signaling pathways to subvert the host intracellular milieu may be an important mechanism for parasite survival.
Collapse
Affiliation(s)
- Robson Sartorello
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.
| | | | | | | |
Collapse
|
29
|
Diambra L, Marchant JS. Localization and socialization: experimental insights into the functional architecture of IP3 receptors. CHAOS (WOODBURY, N.Y.) 2009; 19:037103. [PMID: 19792028 PMCID: PMC2771704 DOI: 10.1063/1.3147425] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 05/11/2009] [Indexed: 05/28/2023]
Abstract
Inositol 1,4,5-trisphosphate (IP(3))-evoked Ca(2+) signals display great spatiotemporal malleability. This malleability depends on diversity in both the cellular organization and in situ functionality of IP(3) receptors (IP(3)Rs) that regulate Ca(2+) release from the endoplasmic reticulum (ER). Recent experimental data imply that these considerations are not independent, such that-as with other ion channels-the local organization of IP(3)Rs impacts their functionality, and reciprocally IP(3)R activity impacts their organization within native ER membranes. Here, we (i) review experimental data that lead to our understanding of the "functional architecture" of IP(3)Rs within the ER, (ii) propose an updated terminology to span the organizational hierarchy of IP(3)Rs observed in intact cells, and (iii) speculate on the physiological significance of IP(3)R socialization in Ca(2+) dynamics, and consequently the emerging need for modeling studies to move beyond gridded, planar, and static simulations of IP(3)R clustering even over short experimental timescales.
Collapse
Affiliation(s)
- Luis Diambra
- Laboratorio de Biología de Sistemas, CREG-UNLP, Buenos Aires, Argentina
| | | |
Collapse
|
30
|
Betzenhauser MJ, Fike JL, Wagner LE, Yule DI. Protein kinase A increases type-2 inositol 1,4,5-trisphosphate receptor activity by phosphorylation of serine 937. J Biol Chem 2009; 284:25116-25. [PMID: 19608738 DOI: 10.1074/jbc.m109.010132] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Protein kinase A (PKA) phosphorylation of inositol 1,4,5-trisphosphate receptors (InsP(3)Rs) represents a mechanism for shaping intracellular Ca(2+) signals following a concomitant elevation in cAMP. Activation of PKA results in enhanced Ca(2+) release in cells that express predominantly InsP(3)R2. PKA is known to phosphorylate InsP(3)R2, but the molecular determinants of this effect are not known. We have expressed mouse InsP(3)R2 in DT40-3KO cells that are devoid of endogenous InsP(3)R and examined the effects of PKA phosphorylation on this isoform in unambiguous isolation. Activation of PKA increased Ca(2+) signals and augmented the single channel open probability of InsP(3)R2. A PKA phosphorylation site unique to the InsP(3)R2 was identified at Ser(937). The enhancing effects of PKA activation on this isoform required the phosphorylation of Ser(937), since replacing this residue with alanine eliminated the positive effects of PKA activation. These results provide a mechanism responsible for the enhanced Ca(2+) signaling following PKA activation in cells that express predominantly InsP(3)R2.
Collapse
Affiliation(s)
- Matthew J Betzenhauser
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, New York 14642, USA
| | | | | | | |
Collapse
|
31
|
Barritt GJ, Litjens TL, Castro J, Aromataris E, Rychkov GY. Store-operated Ca2+ channels and microdomains of Ca2+ in liver cells. Clin Exp Pharmacol Physiol 2009; 36:77-83. [PMID: 19196257 DOI: 10.1111/j.1440-1681.2008.05095.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. Oscillatory increases in the cytoplasmic Ca(2+) concentration ([Ca(2+)](cyt)) play essential roles in the hormonal regulation of liver cells. Increases in [Ca(2+)](cyt) require Ca(2+) release from the endoplasmic reticulum (ER) and Ca(2+) entry across the plasma membrane. 2. Store-operated Ca(2+) channels (SOCs), activated by a decrease in Ca(2+) in the ER lumen, are responsible for maintaining adequate ER Ca(2+). Experiments using patch-clamp recording and the fluorescent Ca(2+) reporter fura-2 indicate there is only one type of SOC in rat liver cells. These SOCs have a high selectivity for Ca(2+) and properties essentially indistinguishable from those of Ca(2+) release-activated Ca(2+) (CRAC) channels. 3. Although Orai1, a CRAC channel pore protein, and stromal interaction molecule 1 (STIM1), a CRAC channel Ca(2+) sensor, are components of liver cell SOCs, the mechanism of activation of SOCs, and in particular the role of subregions of the ER, are not well understood. 4. Recent experiments have used the transient receptor potential vanilloid 1 (TRPV1) non-selective cation channel, ectopically expressed in liver cells, and a choleretic bile acid to deplete Ca(2+) from different ER subregions. The results of these studies have provided evidence that only a small component of the ER is required for STIM1 redistribution and the activation of SOCs. 5. It is concluded that different Ca(2+) microdomains in the ER and cytoplasmic space are important in both the activation of SOCs and in the signalling actions of Ca(2+) in liver cells. Future experiments will investigate the nature of these microdomains further.
Collapse
Affiliation(s)
- Greg J Barritt
- Department of Medical Biochemistry, School of Medicine, Flinders University, Adelaide, South Australia, Australia.
| | | | | | | | | |
Collapse
|
32
|
Rodrigues MA, Gomes DA, Andrade VA, Leite MF, Nathanson MH. Insulin induces calcium signals in the nucleus of rat hepatocytes. Hepatology 2008; 48:1621-31. [PMID: 18798337 PMCID: PMC2825885 DOI: 10.1002/hep.22424] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Insulin is an hepatic mitogen that promotes liver regeneration. Actions of insulin are mediated by the insulin receptor, which is a receptor tyrosine kinase. It is currently thought that signaling via the insulin receptor occurs at the plasma membrane, where it binds to insulin. Here we report that insulin induces calcium oscillations in isolated rat hepatocytes, and that these calcium signals depend upon activation of phospholipase C and the inositol 1,4,5-trisphosphate receptor, but not upon extracellular calcium. Furthermore, insulin-induced calcium signals occur in the nucleus, and are temporally associated with selective depletion of nuclear phosphatidylinositol bisphosphate and translocation of the insulin receptor to the nucleus. These findings suggest that the insulin receptor translocates to the nucleus to initiate nuclear, inositol 1,4,5-trisphosphate-mediated calcium signals in rat hepatocytes. This novel signaling mechanism may be responsible for insulin's effects on liver growth and regeneration.
Collapse
Affiliation(s)
- Michele A Rodrigues
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520-8019, USA
| | | | | | | | | |
Collapse
|
33
|
Abstract
The correct functioning of the liver is ensured by the setting and the maintenance of hepatocyte polarity. The complex polarity of the hepatocyte is characterized by the existence of several basolateral and apical poles per cell. Many in vitro models are available for studying hepatocyte polarity, but which are the more suitable? To answer this question, we aimed to identify criteria which determine the typical hepatocyte polarity. Therefore, we compiled a range of protein markers of membrane domains in rat hepatocytes and investigated their involvement in hepatocytic functions. Then, we focused on the relationship between hepatic functions and the cytoskeleton, Golgi apparatus and endoplasmic reticulum. Subsequently, we compared different cell lines expressing hepatocyte polarity. Finally, to demonstrate the usefulness of some of these lines, we presented new data on endoplasmic reticulum organization in relation to polarity.
Collapse
|
34
|
Ca(2+) -permeable channels in the hepatocyte plasma membrane and their roles in hepatocyte physiology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:651-72. [PMID: 18291110 DOI: 10.1016/j.bbamcr.2008.01.016] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Revised: 01/16/2008] [Accepted: 01/17/2008] [Indexed: 01/24/2023]
Abstract
Hepatocytes are highly differentiated and spatially polarised cells which conduct a wide range of functions, including intermediary metabolism, protein synthesis and secretion, and the synthesis, transport and secretion of bile acids. Changes in the concentrations of Ca(2+) in the cytoplasmic space, endoplasmic reticulum (ER), mitochondria, and other intracellular organelles make an essential contribution to the regulation of these hepatocyte functions. While not yet fully understood, the spatial and temporal parameters of the cytoplasmic Ca(2+) signals and the entry of Ca(2+) through Ca(2+)-permeable channels in the plasma membrane are critical to the regulation by Ca(2+) of hepatocyte function. Ca(2+) entry across the hepatocyte plasma membrane has been studied in hepatocytes in situ, in isolated hepatocytes and in liver cell lines. The types of Ca(2+)-permeable channels identified are store-operated, ligand-gated, receptor-activated and stretch-activated channels, and these may vary depending on the animal species studied. Rat liver cell store-operated Ca(2+) channels (SOCs) have a high selectivity for Ca(2+) and characteristics similar to those of the Ca(2+) release activated Ca(2+) channels in lymphocytes and mast cells. Liver cell SOCs are activated by a decrease in Ca(2+) in a sub-region of the ER enriched in type1 IP(3) receptors. Activation requires stromal interaction molecule type 1 (STIM1), and G(i2alpha,) F-actin and PLCgamma1 as facilitatory proteins. P(2x) purinergic channels are the only ligand-gated Ca(2+)-permeable channels in the liver cell membrane identified so far. Several types of receptor-activated Ca(2+) channels have been identified, and some partially characterised. It is likely that TRP (transient receptor potential) polypeptides, which can form Ca(2+)- and Na(+)-permeable channels, comprise many hepatocyte receptor-activated Ca(2+)-permeable channels. A number of TRP proteins have been detected in hepatocytes and in liver cell lines. Further experiments are required to characterise the receptor-activated Ca(2+) permeable channels more fully, and to determine the molecular nature, mechanisms of activation, and precise physiological functions of each of the different hepatocyte plasma membrane Ca(2+) permeable channels.
Collapse
|
35
|
Gomes DA, Rodrigues MA, Leite MF, Gomez MV, Varnai P, Balla T, Bennett AM, Nathanson MH. c-Met must translocate to the nucleus to initiate calcium signals. J Biol Chem 2007; 283:4344-51. [PMID: 18073207 DOI: 10.1074/jbc.m706550200] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Hepatocyte growth factor (HGF) is important for cell proliferation, differentiation, and related activities. HGF acts through its receptor c-Met, which activates downstream signaling pathways. HGF binds to c-Met at the plasma membrane, where it is generally believed that c-Met signaling is initiated. Here we report that c-Met rapidly translocates to the nucleus upon stimulation with HGF. Ca(2+) signals that are induced by HGF result from phosphatidylinositol 4,5-bisphosphate hydrolysis and inositol 1,4,5-trisphosphate formation within the nucleus rather than within the cytoplasm. Translocation of c-Met to the nucleus depends upon the adaptor protein Gab1 and importin beta1, and formation of Ca(2+) signals in turn depends upon this translocation. HGF may exert its particular effects on cells because it bypasses signaling pathways in the cytoplasm to directly activate signaling pathways in the nucleus.
Collapse
Affiliation(s)
- Dawidson A Gomes
- Department of Internal Medicine and Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520-8019, USA
| | | | | | | | | | | | | | | |
Collapse
|
36
|
VanHouten JN, Wysolmerski JJ. Transcellular calcium transport in mammary epithelial cells. J Mammary Gland Biol Neoplasia 2007; 12:223-35. [PMID: 17999165 DOI: 10.1007/s10911-007-9057-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Accepted: 10/25/2007] [Indexed: 10/22/2022] Open
Abstract
The time-honored paradigm for mammary gland transepithelial calcium transport into milk is centered on the view that most, if not all, calcium enters milk through the secretory pathway, and no ionic calcium directly crosses the apical plasma membrane. Data from several recent studies all strongly suggest that most calcium, in fact, is extruded across the apical plasma membrane directly by the plasma membrane calcium-ATPase isoform 2 (PMCA2). In this review we break down transcellular calcium transport into the tasks of calcium entry, calcium sequestration and compartmentalization, and calcium extrusion. We compare and contrast the steps of calcium transport into milk by mammary epithelial cells, and the specific molecules that might perform these tasks, with well-characterized calcium transport mechanisms in other epithelia, such as the kidney, small intestine, and salivary gland. Finally, we suggest an updated model for calcium transport into milk that incorporates calcium transport across the apical plasma membrane.
Collapse
Affiliation(s)
- Joshua N VanHouten
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, P.O. Box 208020, New Haven, CT 06520-8020, USA.
| | | |
Collapse
|
37
|
Nagata J, Guerra MT, Shugrue CA, Gomes DA, Nagata N, Nathanson MH. Lipid rafts establish calcium waves in hepatocytes. Gastroenterology 2007; 133:256-67. [PMID: 17631147 PMCID: PMC2825880 DOI: 10.1053/j.gastro.2007.03.115] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Accepted: 03/22/2007] [Indexed: 01/09/2023]
Abstract
BACKGROUND & AIMS Polarity is critical for hepatocyte function. Ca(2+) waves are polarized in hepatocytes because the inositol 1,4,5-trisphosphate receptor (InsP3R) is concentrated in the pericanalicular region, but the basis for this localization is unknown. We examined whether pericanalicular localization of the InsP3R and its action to trigger Ca(2+) waves depends on lipid rafts. METHODS Experiments were performed using isolated rat hepatocyte couplets and pancreatic acini, plus SkHep1 cells as nonpolarized controls. The cholesterol depleting agent methyl-beta-cyclodextrin (mbetaCD) was used to disrupt lipid rafts. InsP3R isoforms were examined by immunoblot and immunofluorescence. Ca(2+) waves were examined by confocal microscopy. RESULTS Type II InsP3Rs initially were localized to only some endoplasmic reticulum fractions in hepatocytes, but redistributed into all fractions in mbetaCD-treated cells. This InsP3R isoform was concentrated in the pericanalicular region, but redistributed throughout the cell after mbetaCD treatment. Vasopressin-induced Ca(2+) signals began as apical-to-basal Ca(2+) waves, and mbetaCD slowed the wave speed and prolonged the rise time. MbetaCD had a similar effect on Ca(2+) waves in acinar cells but did not affect Ca(2+) signals in SkHep1 cells, suggesting that cholesterol depletion has similar effects among polarized epithelia, but this is not a nonspecific effect of mbetaCD. CONCLUSIONS Lipid rafts are responsible for the pericanalicular accumulation of InsP3R in hepatocytes, and for the polarized Ca(2+) waves that result. Signaling microdomains exist not only in the plasma membrane, but also in the nearby endoplasmic reticulum, which in turn, helps establish and maintain structural and functional polarity.
Collapse
Affiliation(s)
- Jun Nagata
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8019, USA
| | | | | | | | | | | |
Collapse
|