1
|
Pelizzoni I, Zacchetti D, Campanella A, Grohovaz F, Codazzi F. Iron uptake in quiescent and inflammation-activated astrocytes: a potentially neuroprotective control of iron burden. Biochim Biophys Acta Mol Basis Dis 2013; 1832:1326-33. [PMID: 23583428 PMCID: PMC3787737 DOI: 10.1016/j.bbadis.2013.04.007] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 03/28/2013] [Accepted: 04/03/2013] [Indexed: 02/03/2023]
Abstract
Astrocytes play a crucial role in proper iron handling within the central nervous system. This competence can be fundamental, particularly during neuroinflammation, and neurodegenerative processes, where an increase in iron content can favor oxidative stress, thereby worsening disease progression. Under these pathological conditions, astrocytes undergo a process of activation that confers them either a beneficial or a detrimental role on neuronal survival. Our work investigates the mechanisms of iron entry in cultures of quiescent and activated hippocampal astrocytes. Our data confirm that the main source of iron is the non-transferrin-bound iron (NTBI) and show the involvement of two different routes for its entry: the resident transient receptor potential (TRP) channels in quiescent astrocytes and the de novo expressed divalent metal transporter 1 (DMT1) in activated astrocytes, which accounts for a potentiation of iron entry. Overall, our data suggest that at rest, but even more after activation, astrocytes have the potential to buffer the excess of iron, thereby protecting neurons from iron overload. These findings further extend our understanding of the protective role of astrocytes under the conditions of iron-mediated oxidative stress observed in several neurodegenerative conditions. Non-transferrin-bound iron (NTBI) is the main source of iron for astrocytes. TRPC channels represent an entry pathway for Fe2 + in resting astrocytes. Activation process increases the competence of astrocytes to uptake iron. DMT1 expression accounts for potentiation of iron ingress in activated astrocytes.
Collapse
Affiliation(s)
- Ilaria Pelizzoni
- San Raffaele Scientific Institute, via Olgettina 60, 20132 Milano, Italy
| | | | | | | | | |
Collapse
|
2
|
Smyth JT, Dehaven WI, Jones BF, Mercer JC, Trebak M, Vazquez G, Putney JW. Emerging perspectives in store-operated Ca2+ entry: Roles of Orai, Stim and TRP. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:1147-60. [PMID: 17034882 DOI: 10.1016/j.bbamcr.2006.08.050] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Accepted: 08/30/2006] [Indexed: 11/28/2022]
Abstract
Depletion of intracellular Ca2+ stores induces Ca2+ influx across the plasma membrane through store-operated channels (SOCs). This store-operated Ca2+ influx is important for the replenishment of the Ca2+ stores, and is also involved in many signaling processes by virtue of the ability of intracellular Ca2+ to act as a second messenger. For many years, the molecular identities of particular SOCs, as well as the signaling mechanisms by which these channels are activated, have been elusive. Recently, however, the mammalian proteins STIM1 and Orai1 were shown to be necessary for the activation of store-operated Ca2+ entry in a variety of mammalian cells. Here we present molecular, pharmacological, and electrophysiological properties of SOCs, with particular focus on the roles that STIM1 and Orai1 may play in the signaling processes that regulate various pathways of store-operated entry.
Collapse
Affiliation(s)
- Jeremy T Smyth
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health/DHHS, Research Triangle Park, NC 27709, USA
| | | | | | | | | | | | | |
Collapse
|
3
|
|
4
|
Pizzo P, Burgo A, Pozzan T, Fasolato C. Role of capacitative calcium entry on glutamate-induced calcium influx in type-I rat cortical astrocytes. J Neurochem 2001; 79:98-109. [PMID: 11595762 DOI: 10.1046/j.1471-4159.2001.00539.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Capacitative calcium entry (CCE) has been described in a variety of cell types. To date, little is known about its role in the CNS, and in particular in the cross-talk between glia and neurons. We have first analyzed the properties of CCE of astrocytes in culture, in comparison with that of the rat basophilic leukemia cell line (RBL-2H3), a model where calcium release-activated Ca2+ (CRAC) channels have been unambiguously correlated with CCE. We here show that (i) in astrocytes CCE activated by store depletion and Ca2+ influx induced by glutamate share the same pharmacological profile of CCE in RBL-2H3 cells and (ii) glutamate-induced Ca2+ influx in astrocytes plays a primary role in glutamate-dependent intracellular Ca2+ concentration ([Ca2+]i) oscillations, being these latter reduced in frequency and amplitude by micromolar concentrations of La3+. Finally, we compared the expression of various mammalian transient receptor potential genes (TRP) in astrocytes and RBL-2H3 cells. Despite the similar pharmacological properties of CCE in these cells, the pattern of TRP expression is very different. The involvement of CCE and TRPs in glutamate dependent activation of astrocytes is discussed.
Collapse
Affiliation(s)
- P Pizzo
- Department of Biomedical Sciences and the National Research Council Center for the Study of Biomembranes, University of Padua, Padua, Italy
| | | | | | | |
Collapse
|
5
|
Kondo I. Protein kinase C potentiates capacitative Ca2+ entry that links to steroidogenesis in bovine adrenocortical cells. JAPANESE JOURNAL OF PHARMACOLOGY 2000; 82:210-7. [PMID: 10887951 DOI: 10.1254/jjp.82.210] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
I investigated the role of protein kinase C (PKC) in regulation of the capacitative Ca2+ entry and steroidogenesis in bovine adrenocortical (BA) cells. Thapsigargin (TG)-treatment depleted intracellular Ca2+ stores followed by induction of Ca2+ influx from the extracellular pool and also increasing of Mn2+ influx as an indicator of divalent cation influx in BA cells. Calphostin C, a PKC inhibitor, inhibited the TG-induced [Ca2+]i elevation dose-dependently (0.1-1 microM) and attenuated Mn2+ entry. Phorbol 12-myristate 13-acetate (PMA), an activator of PKC, potentiated the elevation of [Ca2+]i and enhanced Mn2+ entry by TG treatment. These results suggest that PKC may modulate capacitative Ca2+ entry in BA cells. In the presence of extracellular Ca2+, TG enhanced cortisol production in BA cells. Calphostin C attenuated the TG-induced steroidogenesis dose-dependently (0.25-1 microM). PMA enhanced the steroidogenesis dose-dependently (1-100 nM). These results suggested that PKC may have a modulatory effect on the capacitative Ca2+ entry that links to steroidogenesis in BA cells.
Collapse
Affiliation(s)
- I Kondo
- Department of Anesthesiology, Jikei University School of Medicine, Tokyo, Japan
| |
Collapse
|
6
|
Leung YM, Kwan CY. Current perspectives in the pharmacological studies of store-operated Ca2+ entry blockers. JAPANESE JOURNAL OF PHARMACOLOGY 1999; 81:253-8. [PMID: 10622212 DOI: 10.1254/jjp.81.253] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The store-operated Ca2+ entry (SOCE) pathway has aroused much interest recently not only because of its unusual nature as retrograde signaling, but also due to its wide occurrence and its possible role in physiological and pathophysiological situations. A number of synthetic or naturally occurring drugs recently used to block this Ca2+ entry pathway are briefly reviewed. Although important and interesting information has been obtained using these putative SOCE blockers described in this review, they indeed have sites of action other than the SOCE channels, and caution must be exercised in using them as putative tools to study SOCE. For instance, the highly variable potency of some synthetic blockers (SK&F 96365 and LOE 908) to inhibit SOCE has provided indirect evidence for the heterogeneous nature of the SOCE channels, an observation consistent with the differential Mn2+ permeability through SOCE in various cell types. The use of SK&F 96365 at relatively high concentrations has unexpectedly revealed its potential as an opener of a novel cation entry pathway. The ability of LU52396 to discriminate the SOCE channel in its closed/open states may be useful in the analysis of the kinetics of SOCE channel activation/inactivation. The possible presence of both agonistic and antagonistic saponins derived from ginseng plants for the study of SOCE deserves more rigorous experimental investigations, which may lay new ground for the development of new types of Ca2+ antagonists (and/or agonists) from the natural resources.
Collapse
Affiliation(s)
- Y M Leung
- Department of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
| | | |
Collapse
|
7
|
Zhang MI, O'Neil RG. The diversity of calcium channels and their regulation in epithelial cells. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1999; 46:43-83. [PMID: 10332501 DOI: 10.1016/s1054-3589(08)60469-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- M I Zhang
- Department of Integrative Biology, Pharmacology, and Physiology, University of Texas-Houston Health Science Center 77030, USA
| | | |
Collapse
|
8
|
Leung YM, Kwan CY. Current Perspectives in the Pharmacological Studies of Store-Operated Ca2+ Entry Blockers. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s0021-5198(19)30761-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
9
|
Gamberucci A, Fulceri R, Benedetti A, Bygrave FL. On the mechanism of action of econazole, the capacitative calcium inflow blocker. Biochem Biophys Res Commun 1998; 248:75-7. [PMID: 9675088 DOI: 10.1006/bbrc.1998.8810] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ability of bovine serum albumin to reverse the inhibitory action of econazole and the unsaturated fatty acid oleate on store-dependent Ca2+ inflow was examined in Ehrlich ascites tumour cells. We report that inhibition of Ca2+ inflow by both compounds is reversed immediately upon addition of bovine serum albumin. It is concluded that the inhibitory action of econazole resembles that of unsaturated fatty acids. The mechanism appears to be one pertaining to nonspecific events at the plasma membrane, possibly involving alterations in plasma membrane fluidity/structure.
Collapse
Affiliation(s)
- A Gamberucci
- Istituto di Patologia Generale, Universita di Siena, Italy
| | | | | | | |
Collapse
|
10
|
Smaili SS, Cavalcanti PM, Oshiro ME, Ferreira AT, Jurkiewicz A. Ca2+ release-activated channels in rat stomach smooth muscle cells. Eur J Pharmacol 1998; 342:119-22. [PMID: 9544800 DOI: 10.1016/s0014-2999(97)01537-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In rat stomach fundus, contractions induced by Ca2+ (1.8 mM) were strikingly potentiated by thapsigargin. This potentiation was partially inhibited by the blockers of Ca2+ release activated channels (CRACs), miconazole and SK&F96365 ([1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole, HCL]) and slightly blocked by the antagonist of calcium voltage-operated channels (VOCs), isradipine. In dissociated cells in a 0Ca solution, thapsigargin potentiated the increase in intracellular calcium after reintroduction of Ca2+. This potentiation was partially reduced by the CRAC blockers, but not by the VOC blockers. This data suggests that calcium influx increased due to the depletion of intracellular calcium by thapsigargin and that this influx occurs predominantly through CRACs.
Collapse
Affiliation(s)
- S S Smaili
- Department of Pharmacology, Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil
| | | | | | | | | |
Collapse
|
11
|
Guse AH, de Wit C, Klokow T, Schweitzer K, Mayr GW. Unique properties of the capacitative Ca(2+)-entry antagonist LU 52396: its inhibitory activity depends on the activation state of the cells. Cell Calcium 1997; 22:91-7. [PMID: 9292227 DOI: 10.1016/s0143-4160(97)90109-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The pharmacological properties of the recently described antagonist for capacitative Ca2+ entry LU 52396 were investigated and compared to known Ca2+ antagonists in Jurkat T-lymphocytes. In the first set of experiments, cells were stimulated with the anti-CD3 monoclonal antibody OKT3 and, subsequently, Ca2+ antagonists were added. Under such conditions SK-F 96365, econazole, nitrendipine and ZnCl2 dose-dependently antagonized Ca2+ signaling, whereas LU 52396 in concentrations up to 100 microM did not. In contrast, when LU 52396 was added a few minutes before OKT3, a dose-dependent inhibition of the OKT3-stimulated Ca2+ signals by LU 52396 was observed. Likewise, by prior addition of LU 52396 to thapsigargin-stimulated Jurkat T cells, a dose-dependent inhibition of Ca2+ signals was achieved. The IC50 value of LU 52396 for both agonists was about 5 microM. LU 52396 also inhibited Jurkat T cell proliferation, but showed cytotoxic effects at concentrations > 50 microM. Our data indicate that, in contrast to the other Ca2+ antagonists SK-F 96365, econazole, nitrendipine and ZnCl2, LU 52396 recognized the channel for capacitative Ca2+ entry only when intracellular Ca2+ was low and the channel was in its closed state.
Collapse
Affiliation(s)
- A H Guse
- Department of Enzyme Chemistry, University of Hamburg, Germany
| | | | | | | | | |
Collapse
|
12
|
Cho JH, Balasubramanyam M, Chernaya G, Gardner JP, Aviv A, Reeves JP, Dargis PG, Christian EP. Oligomycin inhibits store-operated channels by a mechanism independent of its effects on mitochondrial ATP. Biochem J 1997; 324 ( Pt 3):971-80. [PMID: 9210424 PMCID: PMC1218516 DOI: 10.1042/bj3240971] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Inhibitors of mitochondrial oxidative metabolism have been proposed to interfere with Ca2+ influx mediated by store-operated channels (SOC), secondary to their effects on ATP production. We assessed SOC activity by 45Ca2+ influx and fluorimetric measurements of free Ca2+ or Mn2+ quench in thapsigargin-treated Chinese hamster ovary cells and Jurkat T-cells, and additionally by electrophysiological measurements of the Ca2+-release-activated Ca2+ current (Icrac) in Jurkat T-cells. Various mitochondrial antagonists were confirmed to inhibit SOC. However, the following evidence supported the proposal that oligomycin, in particular, exerts an inhibitory effect on SOC in addition to its known actions on mitochondria and Na+-pump activity: (i) the concentrations of oligomycin required to inhibit SOC-mediated Ca2+ influx or Icrac (half-inhibitory concentration approximately 2 microM) were nearly 50-fold higher than the concentrations that blocked mitochondrial ATP production; (ii) the rank order of potency of oligomycins A, B and C for decreasing SOC-mediated Ca2+ influx or Icrac differed from that known for inhibition of mitochondrial function; (iii) oligomycin blocked Icrac under voltage clamp and with intracellular Na+ and K+ concentrations fixed by dialysis from the patch pipette, arguing that the effect was not secondary to membrane polarization or pump activity; and (iv) fixing the cytosolic ATP concentration by dialysis from the patch pipette attenuated rotenone- but not oligomycin-mediated inhibition of Icrac. Oligomycin also blocked volume-activated Cl- currents, a profile common to some other known blockers of SOC that are not known mitochondrial inhibitors. These findings raise the possibility that oligomycin interacts directly with SOC, and thus may extend the known pharmacological profile for this type of Ca2+-influx pathway.
Collapse
Affiliation(s)
- J H Cho
- Hypertension Research Program, University of Medicine and Dentistry-New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Gamberucci A, Fulceri R, Benedetti A. Inhibition of store-dependent capacitative Ca2+ influx by unsaturated fatty acids. Cell Calcium 1997; 21:375-85. [PMID: 9174650 DOI: 10.1016/s0143-4160(97)90031-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The effects of the unsaturated fatty acids, arachidonic and oleic acid, on the influx of Ca2+ activated by depletion of intracellular stores with thapsigargin were investigated in various cell types. By using a Ca2+ free/Ca2+ reintroduction protocol, we observed that arachidonic acid (2 to 5 microM) inhibited thapsigargin-induced rises in cytosolic free Ca2+ ([Ca2+]i) in Ehrlich tumor cells, Jurkat T lymphocytes, rat thymocytes, and Friend erythroleukemia and PC12 rat pheochromocytoma cells. This effect was attributed to the inhibition of Ca2+ entry, since arachidonate also inhibited thapsigargin-stimulated unidirectional entry of the Ca2+ surrogates Ba2+ and Mn2+. In Ehrlich cells, the IC50 for arachidonic and oleic acid was 1.2 and 1.8 microM, respectively. The inhibition appeared to depend on the ratio [fatty acid]/[cells] rather than on the absolute fatty acid concentration. Experiments with [3H]-oleic acid revealed that the inhibitory activity was not correlated with cell internalisation and metabolism of the fatty acid. The inhibition was reverted by removal of the fatty acid bound to cell membrane by fatty acid-free albumin treatment. The unsaturated fatty acids had no effect on ATP/ADP cell levels and plasma membrane potential. Pharmacological evidence indicated that cell phosphorylation/dephosphorylation events, and pertussis toxin-sensitive G proteins were not involved. Other amphipathic lipophilic compounds, i.e. 2-bromopalmitic acid, retinoic acid, sphingosine, and dihydrosphingosine, mimicked arachidonic/oleic acid as they inhibited thapsigargin-stimulated Ca2+ influx in an albumin-reversible fashion. These results suggest that physiologically relevant (unsaturated) fatty acids can inhibit capacitative Ca2+ influx possibly because they intercalate into the plasma membrane and directly affect the activity of the channels involved.
Collapse
Affiliation(s)
- A Gamberucci
- Istituto di Patologia Generale, Università di Siena, Italy
| | | | | |
Collapse
|
14
|
Favre CJ, Nüsse O, Lew DP, Krause KH. Store-operated Ca2+ influx: what is the message from the stores to the membrane? THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 1996; 128:19-26. [PMID: 8759933 DOI: 10.1016/s0022-2143(96)90110-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- C J Favre
- Division of Infectious Diseases, University Hospital, Geneva, Switzerland
| | | | | | | |
Collapse
|
15
|
Clementi E, Meldolesi J. Pharmacological and functional properties of voltage-independent Ca2+ channels. Cell Calcium 1996; 19:269-79. [PMID: 8983848 DOI: 10.1016/s0143-4160(96)90068-8] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
During the last few years, considerable progress has taken place in our knowledge of the molecular and functional properties of the various voltage-independent Ca2+ channels. In addition to the ionotropic receptor-channels (ROCs), that are not discussed in the present review, these channels include the SMOCs, activated via second messengers or other transducing processes directly triggered by receptor activation; and the SOCCs, activated as a consequence of depletion of the rapidly exchanging Ca2+ stores in the cytoplasm. In parallel, a pharmacological approach to the study of these channels has been developed, based primarily on heterogeneous drugs already known for different biological effects, and subsequently recognized as voltage-independent Ca(2+)-channel blockers. From the systematic analysis of the effects of these drugs new information has emerged about SMOCs and SOCCs function. In addition, pharmacological blockade of these channels appears to have beneficial therapeutic effects in pathological conditions such as tumoral cell growth, inflammation and immunity. At the moment the field is rapidly evolving, with major developments expected in the years ahead.
Collapse
Affiliation(s)
- E Clementi
- Department of Pharmacology, University of Reggio Calabria, Catanzaro, Italy.
| | | |
Collapse
|