1
|
Jiang Y, Tan Y, Xiao K, Li X, Shao K, Song J, Kong X, Shi J. pH-Regulating Nanoplatform for the "Double Channel Chase " of Tumor Cells by the Synergistic Cascade between Chlorine Treatment and Methionine-Depletion Starvation Therapy. ACS APPLIED MATERIALS & INTERFACES 2021; 13:54690-54705. [PMID: 34761894 DOI: 10.1021/acsami.1c14802] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
During rapid proliferation and metabolism, tumor cells show a high dependence on methionine. The deficiency of methionine exhibits significant inhibition on tumor growth, which provides a potential therapeutic target in tumor therapy. Herein, ClO2-loaded nanoparticles (fluvastatin sodium&metformin&bupivacaine&ClO2@CaSiO3@MnO2-arginine-glycine-aspatic acid (RGD) (MFBC@CMR) NPs) were prepared for synergistic chlorine treatment and methionine-depletion starvation therapy. After outer layer MnO2 was degraded in the high glutathione (GSH) tumor microenvironment (TME), MFBC@CMR NPs released metformin (Me) to target the mitochondria, thus interfering with the tricarboxylic acid (TCA) cycle and promoting the production of lactate. In addition, released fluvastatin sodium (Flu) by the NPs acted on monocarboxylic acid transporter 4 (MCT4) in the cell membrane to inhibit lactate leakage and induce a decrease of intracellular pH, further prompting the NPs to release chlorine dioxide (ClO2), which then oxidized methionine, inhibited tumor growth, and produced large numbers of Cl- in the cytoplasm. Cl- could enter mitochondria through the voltage-dependent anion channel (VDAC) channel, which was opened by bupivacaine (Bup). The disruption of Cl- homeostasis promotes mitochondrial damage and membrane potential decline, leading to the release of cytochrome C (Cyt-C) and apoptosis inducing factor (AIF) and further inducing cell apoptosis. To sum up, the pH-regulating and ClO2-loaded MFBC@CMR nanoplatform can achieve cascade chlorine treatment and methionine-depletion starvation therapy toward tumor cells, which is of great significance for improving the clinical tumor treatment effect.
Collapse
Affiliation(s)
- Yuping Jiang
- College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, 700 Changcheng Road, 266109 Qingdao, China
| | - Yulong Tan
- Special Food Research Institute and Qingdao Special Food Research Institute, Qingdao Agricultural University, 700 Changcheng Road, 266109 Qingdao, China
| | - Kefeng Xiao
- College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, 700 Changcheng Road, 266109 Qingdao, China
| | - Xiaoshuang Li
- School of Management, Qingdao Agricultural University, 700 Changcheng Road, 266109 Qingdao, China
| | - Kai Shao
- Department of Central Laboratory, Qilu Hospital (Qingdao), Cheeloo College of Medicine, Shandong University, 758 Hefei Road, 266035 Qingdao, China
| | - Junyao Song
- Bassars College of Future Agricultural Science and Technology, Qingdao Agricultural University, 700 Changcheng Road, 266109 Qingdao, China
| | - Xiaoying Kong
- College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, 700 Changcheng Road, 266109 Qingdao, China
| | - Jinsheng Shi
- College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, 700 Changcheng Road, 266109 Qingdao, China
| |
Collapse
|
2
|
Tadini-Buoninsegni F. Protein Adsorption on Solid Supported Membranes: Monitoring the Transport Activity of P-Type ATPases. Molecules 2020; 25:molecules25184167. [PMID: 32933017 PMCID: PMC7570688 DOI: 10.3390/molecules25184167] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/01/2020] [Accepted: 09/02/2020] [Indexed: 02/07/2023] Open
Abstract
P-type ATPases are a large family of membrane transporters that are found in all forms of life. These enzymes couple ATP hydrolysis to the transport of various ions or phospholipids across cellular membranes, thereby generating and maintaining crucial electrochemical potential gradients. P-type ATPases have been studied by a variety of methods that have provided a wealth of information about the structure, function, and regulation of this class of enzymes. Among the many techniques used to investigate P-type ATPases, the electrical method based on solid supported membranes (SSM) was employed to investigate the transport mechanism of various ion pumps. In particular, the SSM method allows the direct measurement of charge movements generated by the ATPase following adsorption of the membrane-bound enzyme on the SSM surface and chemical activation by a substrate concentration jump. This kind of measurement was useful to identify electrogenic partial reactions and localize ion translocation in the reaction cycle of the membrane transporter. In the present review, we discuss how the SSM method has contributed to investigate some key features of the transport mechanism of P-type ATPases, with a special focus on sarcoplasmic reticulum Ca2+-ATPase, mammalian Cu+-ATPases (ATP7A and ATP7B), and phospholipid flippase ATP8A2.
Collapse
|
3
|
Aguayo-Ortiz R, Espinoza-Fonseca LM. Linking Biochemical and Structural States of SERCA: Achievements, Challenges, and New Opportunities. Int J Mol Sci 2020; 21:ijms21114146. [PMID: 32532023 PMCID: PMC7313052 DOI: 10.3390/ijms21114146] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/05/2020] [Accepted: 06/08/2020] [Indexed: 02/07/2023] Open
Abstract
Sarcoendoplasmic reticulum calcium ATPase (SERCA), a member of the P-type ATPase family of ion and lipid pumps, is responsible for the active transport of Ca2+ from the cytoplasm into the sarcoplasmic reticulum lumen of muscle cells, into the endoplasmic reticulum (ER) of non-muscle cells. X-ray crystallography has proven to be an invaluable tool in understanding the structural changes of SERCA, and more than 70 SERCA crystal structures representing major biochemical states (defined by bound ligand) have been deposited in the Protein Data Bank. Consequently, SERCA is one of the best characterized components of the calcium transport machinery in the cell. Emerging approaches in the field, including spectroscopy and molecular simulation, now help integrate and interpret this rich structural information to understand the conformational transitions of SERCA that occur during activation, inhibition, and regulation. In this review, we provide an overview of the crystal structures of SERCA, focusing on identifying metrics that facilitate structure-based categorization of major steps along the catalytic cycle. We examine the integration of crystallographic data with different biophysical approaches and computational methods to link biochemical and structural states of SERCA that are populated in the cell. Finally, we discuss the challenges and new opportunities in the field, including structural elucidation of functionally important and novel regulatory complexes of SERCA, understanding the structural basis of functional divergence among homologous SERCA regulators, and bridging the gap between basic and translational research directed toward therapeutic modulation of SERCA.
Collapse
|
4
|
Tadini-Buoninsegni F, Sordi G, Smeazzetto S, Natile G, Arnesano F. Effect of cisplatin on the transport activity of P II-type ATPases. Metallomics 2018. [PMID: 28636017 DOI: 10.1039/c7mt00100b] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Cisplatin (cis-diamminedichlorido-Pt(ii)) is extensively used as a chemotherapeutic agent against various types of tumors. However, cisplatin administration causes serious side effects, including nephrotoxicity, ototoxicity and neurotoxicity. It has been shown that cisplatin can interact with P-type ATPases, e.g., Cu+-ATPases (ATP7A and ATP7B) and Na+,K+-ATPase. Cisplatin-induced inhibition of Na+,K+-ATPase has been related to the nephrotoxic effect of the drug. To investigate the inhibitory effects of cisplatin on the pumping activity of PII-type ATPases, electrical measurements were performed on sarcoplasmic reticulum Ca2+-ATPase (SERCA) and Na+,K+-ATPase embedded in vesicles/membrane fragments adsorbed on a solid-supported membrane. We found that cisplatin inhibits SERCA and Na+,K+-ATPase only when administered without a physiological reducing agent (GSH); in contrast, inhibition was also observed in the case of Cu+-ATPases in the presence of 1 mM GSH. Our results indicate that cisplatin is a much stronger inhibitor of SERCA (with an IC50 value of 1.3 μM) than of Na+,K+-ATPase (with an IC50 value of 11.1 μM); moreover, cisplatin inhibition of Na+,K+-ATPase is reversible, whereas it is irreversible in the case of SERCA. In the absence of a physiological substrate, while Cu+-ATPases are able to translocate cisplatin, SERCA and Na+,K+-ATPase do not perform ATP-dependent cisplatin displacement.
Collapse
|
5
|
Tadini-Buoninsegni F, Smeazzetto S, Gualdani R, Moncelli MR. Drug Interactions With the Ca 2+-ATPase From Sarco(Endo)Plasmic Reticulum (SERCA). Front Mol Biosci 2018; 5:36. [PMID: 29696147 PMCID: PMC5904271 DOI: 10.3389/fmolb.2018.00036] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 03/26/2018] [Indexed: 11/13/2022] Open
Abstract
The sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) is an intracellular membrane transporter that utilizes the free energy provided by ATP hydrolysis for active transport of Ca2+ ions from the cytoplasm to the lumen of sarco(endo)plasmic reticulum. SERCA plays a fundamental role for cell calcium homeostasis and signaling in muscle cells and also in cells of other tissues. Because of its prominent role in many physiological processes, SERCA dysfunction is associated to diseases displaying various degrees of severity. SERCA transport activity can be inhibited by a variety of compounds with different chemical structures. Specific SERCA inhibitors were identified which have been instrumental in studies of the SERCA catalytic and transport mechanism. It has been proposed that SERCA inhibition may represent a novel therapeutic strategy to cure certain diseases by targeting SERCA activity in pathogens, parasites and cancer cells. Recently, novel small molecules have been developed that are able to stimulate SERCA activity. Such SERCA activators may also offer an innovative and promising therapeutic approach to treat diseases, such as heart failure, diabetes and metabolic disorders. In the present review the effects of pharmacologically relevant compounds on SERCA transport activity are presented. In particular, we will discuss the interaction of SERCA with specific inhibitors and activators that are potential therapeutic agents for different diseases.
Collapse
Affiliation(s)
| | - Serena Smeazzetto
- Department of Chemistry "Ugo Schiff," University of Florence, Florence, Italy
| | - Roberta Gualdani
- Laboratory of Cell Physiology, Institute of Neuroscience, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Maria Rosa Moncelli
- Department of Chemistry "Ugo Schiff," University of Florence, Florence, Italy
| |
Collapse
|
6
|
Smeazzetto S, Armanious GP, Moncelli MR, Bak JJ, Lemieux MJ, Young HS, Tadini-Buoninsegni F. Conformational memory in the association of the transmembrane protein phospholamban with the sarcoplasmic reticulum calcium pump SERCA. J Biol Chem 2017; 292:21330-21339. [PMID: 29081402 DOI: 10.1074/jbc.m117.794453] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 10/19/2017] [Indexed: 11/06/2022] Open
Abstract
The sarcoplasmic reticulum Ca2+-ATPase SERCA promotes muscle relaxation by pumping calcium ions from the cytoplasm into the sarcoplasmic reticulum. SERCA activity is regulated by a variety of small transmembrane peptides, most notably by phospholamban in cardiac muscle and sarcolipin in skeletal muscle. However, how phospholamban and sarcolipin regulate SERCA is not fully understood. In the present study, we evaluated the effects of phospholamban and sarcolipin on calcium translocation and ATP hydrolysis by SERCA under conditions that mimic environments in sarcoplasmic reticulum membranes. For pre-steady-state current measurements, proteoliposomes containing SERCA and phospholamban or sarcolipin were adsorbed to a solid-supported membrane and activated by substrate concentration jumps. We observed that phospholamban altered ATP-dependent calcium translocation by SERCA within the first transport cycle, whereas sarcolipin did not. Using pre-steady-state charge (calcium) translocation and steady-state ATPase activity under substrate conditions (various calcium and/or ATP concentrations) promoting particular conformational states of SERCA, we found that the effect of phospholamban on SERCA depends on substrate preincubation conditions. Our results also indicated that phospholamban can establish an inhibitory interaction with multiple SERCA conformational states with distinct effects on SERCA's kinetic properties. Moreover, we noted multiple modes of interaction between SERCA and phospholamban and observed that once a particular mode of association is engaged it persists throughout the SERCA transport cycle and multiple turnover events. These observations are consistent with conformational memory in the interaction between SERCA and phospholamban, thus providing insights into the physiological role of phospholamban and its regulatory effect on SERCA transport activity.
Collapse
Affiliation(s)
- Serena Smeazzetto
- From the Department of Chemistry "Ugo Schiff," University of Florence, 50019 Sesto Fiorentino, Italy and
| | - Gareth P Armanious
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Maria Rosa Moncelli
- From the Department of Chemistry "Ugo Schiff," University of Florence, 50019 Sesto Fiorentino, Italy and
| | - Jessi J Bak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | | |
Collapse
|
7
|
Global Analysis of Type Three Secretion System and Quorum Sensing Inhibition of Pseudomonas savastanoi by Polyphenols Extracts from Vegetable Residues. PLoS One 2016; 11:e0163357. [PMID: 27668874 PMCID: PMC5036890 DOI: 10.1371/journal.pone.0163357] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 09/06/2016] [Indexed: 11/30/2022] Open
Abstract
Protection of plants against bacterial diseases still mainly relies on the use of chemical pesticides, which in Europe correspond essentially to copper-based compounds. However, recently plant diseases control is oriented towards a rational use of molecules and extracts, generally with natural origin, with lower intrinsic toxicity and a reduced negative environmental impact. In this work, polyphenolic extracts from vegetable no food/feed residues of typical Mediterranean crops, as Olea europaea, Cynara scolymus, and Vitis vinifera were obtained and their inhibitory activity on the Type Three Secretion System (TTSS) and the Quorum Sensing (QS) of the Gram-negative phytopathogenic bacterium Pseudomonas savastanoi pv. nerii strain Psn23 was assessed. Extract from green tea (Camellia sinensis) was used as a positive control. Collectively, the data obtained through gfp-promoter fusion system and real-time PCR show that all the polyphenolic extracts here studied have a high inhibitory activity on both the TTSS and QS of Psn23, without any depressing effect on bacterial viability. Extracts from green tea and grape seeds were shown to be the most active. Such activity was confirmed in planta by a strong reduction in the ability of Psn23 to develop hyperplastic galls on explants from adult oleander plants, as well as to elicit hypersensitive response on tobacco. By using a newly developed Congo red assay and an ELISA test, we demonstrated that the TTSS-targeted activity of these polyphenolic extracts also affects the TTSS pilus assembly. In consideration of the potential application of polyphenolic extracts in plant protection, the absence of any toxicity of these polyphenolic compounds was also assessed. A widely and evolutionary conserved molecular target such as Ca2+-ATPase, essential for the survival of any living organism, was used for the toxicity assessment.
Collapse
|
8
|
Sadafi FZ, Massai L, Bartolommei G, Moncelli MR, Messori L, Tadini-Buoninsegni F. Anticancer ruthenium(III) complex KP1019 interferes with ATP-dependent Ca2+ translocation by sarco-endoplasmic reticulum Ca2+-ATPase (SERCA). ChemMedChem 2014; 9:1660-4. [PMID: 24920093 DOI: 10.1002/cmdc.201402128] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Indexed: 01/16/2023]
Abstract
Sarco-endoplasmic reticulum Ca2+-ATPase (SERCA), a P-type ATPase that sustains Ca2+ transport and plays a major role in intracellular Ca2+ homeostasis, represents a therapeutic target for cancer therapy. Here, we investigated whether ruthenium-based anticancer drugs, namely KP1019 (indazolium [trans-tetrachlorobis(1H-indazole)ruthenate(III)]), NAMI-A (imidazolium [trans-tetrachloro(1H-imidazole)(S-dimethylsulfoxide)ruthenate(III)]) and RAPTA-C ([Ru(η6-p-cymene)dichloro(1,3,5-triaza-7-phosphaadamantane)]), and cisplatin (cis-diammineplatinum(II) dichloride) might act as inhibitors of SERCA. Charge displacement by SERCA adsorbed on a solid-supported membrane was measured after ATP or Ca2+ concentration jumps. Our results show that KP1019, in contrast to the other metal compounds, is able to interfere with ATP-dependent translocation of Ca2+ ions. An IC50 value of 1 μM was determined for inhibition of calcium translocation by KP1019. Conversely, it appears that KP1019 does not significantly affect Ca2+ binding to the ATPase from the cytoplasmic side. Inhibition of SERCA at pharmacologically relevant concentrations may represent a crucial aspect in the overall pharmacological and toxicological profile of KP1019.
Collapse
Affiliation(s)
- Fabrizio-Zagros Sadafi
- Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino (Italy); Institute of Particle Technology, University of Erlangen-Nuremberg, 91058 Erlangen (Germany)
| | | | | | | | | | | |
Collapse
|
9
|
Ferrandi M, Barassi P, Tadini-Buoninsegni F, Bartolommei G, Molinari I, Tripodi MG, Reina C, Moncelli MR, Bianchi G, Ferrari P. Istaroxime stimulates SERCA2a and accelerates calcium cycling in heart failure by relieving phospholamban inhibition. Br J Pharmacol 2014; 169:1849-61. [PMID: 23763364 DOI: 10.1111/bph.12278] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 05/10/2013] [Accepted: 05/15/2013] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Calcium handling is known to be deranged in heart failure. Interventions aimed at improving cell Ca(2) (+) cycling may represent a promising approach to heart failure therapy. Istaroxime is a new luso-inotropic compound that stimulates cardiac contractility and relaxation in healthy and failing animal models and in patients with acute heart failure (AHF) syndrome. Istaroxime is a Na-K ATPase inhibitor with the unique property of increasing sarcoplasmic reticulum (SR) SERCA2a activity as shown in heart microsomes from humans and guinea pigs. The present study addressed the molecular mechanism by which istaroxime increases SERCA2a activity. EXPERIMENTAL APPROACH To study the effect of istaroxime on SERCA2a-phospholamban (PLB) complex, we applied different methodologies in native dog healthy and failing heart preparations and heterologous canine SERCA2a/PLB co-expressed in Spodoptera frugiperda (Sf21) insect cells. KEY RESULTS We showed that istaroxime enhances SERCA2a activity, Ca(2) (+) uptake and the Ca(2) (+) -dependent charge movements into dog healthy and failing cardiac SR vesicles. Although not directly demonstrated, the most probable explanation of these activities is the displacement of PLB from SERCA2a.E2 conformation, independently from cAMP/PKA. We propose that this displacement may favour the SERCA2a conformational transition from E2 to E1, thus resulting in the acceleration of Ca(2) (+) cycling. CONCLUSIONS AND IMPLICATIONS Istaroxime represents the first example of a small molecule that exerts a luso-inotropic effect in the failing human heart through the stimulation of SERCA2a ATPase activity and the enhancement of Ca(2) (+) uptake into the SR by relieving the PLB inhibitory effect on SERCA2a in a cAMP/PKA independent way.
Collapse
Affiliation(s)
- Mara Ferrandi
- Prassis Sigma-Tau Research Institute, Settimo Milanese, Milan, Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Sacconi A, Moncelli MR, Margheri G, Tadini-Buoninsegni F. Enhanced adsorption of Ca-ATPase containing vesicles on a negatively charged solid-supported-membrane for the investigation of membrane transporters. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:13883-13889. [PMID: 24131452 DOI: 10.1021/la4034386] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A convenient model system for a biological membrane is a solid-supported membrane (SSM), which consists of a gold-supported alkanethiol|phospholipid bilayer. In combination with a concentration jump method, SSMs have been used for the investigation of several membrane transporters. Vesicles incorporating sarcoplasmic reticulum Ca-ATPase (SERCA) were adsorbed on a negatively charged SSM (octadecanethiol|phosphatidylserine bilayer). The current signal generated by the adsorbed vesicles following an ATP concentration jump was compared to that produced by SERCA-containing vesicles adsorbed on a conventional SSM (octadecanethiol|phosphatidylcholine bilayer). A significantly higher current amplitude was recorded on the serine-based SSM. The adsorption of SERCA-incorporating vesicles on the SSM was then characterized by surface plasmon resonance (SPR). The SPR measurements clearly indicate that in the presence of Ca(2+) and Mg(2+), the amount of adsorbed vesicles on the serine-based SSM is about twice that obtained using the conventional SSM, thereby demonstrating that the higher current amplitude recorded on the negatively charged SSM is correlated with a greater quantity of adsorbed vesicles. The enhanced adsorption of membrane vesicles on the PS-based SSM may be useful to study membrane preparations with a low concentration of transport protein generating small current signals, as in the case of various recombinantly expressed proteins.
Collapse
Affiliation(s)
- Alessio Sacconi
- Department of Chemistry "Ugo Schiff", University of Florence , via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
| | | | | | | |
Collapse
|
11
|
Soler F, Asensio MC, Fernández-Belda F. Inhibition of the intracellular Ca(2+) transporter SERCA (Sarco-Endoplasmic Reticulum Ca(2+)-ATPase) by the natural polyphenol epigallocatechin-3-gallate. J Bioenerg Biomembr 2012; 44:597-605. [PMID: 22851007 DOI: 10.1007/s10863-012-9462-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 07/08/2012] [Indexed: 11/26/2022]
Abstract
The use of a microsomal preparation from skeletal muscle revealed that both Ca(2+) transport and Ca(2+)-dependent ATP hydrolysis linked to Sarco-Endoplasmic Reticulum Ca(2+)-ATPase are inhibited by epigallocatechin-3-gallate (EGCG). A half-maximal effect was achieved at approx. 12 μM. The presence of the galloyl group was essential for the inhibitory effect of the catechin. The relative inhibition of the Ca(2+)-ATPase activity decreased when the Ca(2+) concentration was raised but not when the ATP concentration was elevated. Data on the catalytic cycle indicated inhibition of maximal Ca(2+) binding and a decrease in Ca(2+) binding affinity when measured in the absence of ATP. Moreover, the addition of ATP to samples in the presence of EGCG and Ca(2+) led to an early increase in phosphoenzyme followed by a time-dependent decay that was faster when the drug concentration was raised. However, phosphorylation following the addition of ATP plus Ca(2+) led to a slow rate of phosphoenzyme accumulation that was also dependent on EGCG concentration. The results are consistent with retention of the transporter conformation in the Ca(2+)-free state, thus impeding Ca(2+) binding and therefore the subsequent steps when ATP is added to trigger the Ca(2+) transport process. Furthermore, phosphorylation by inorganic phosphate in the absence of Ca(2+) was partially inhibited by EGCG, suggesting alteration of the native Ca(2+)-free conformation at the catalytic site.
Collapse
Affiliation(s)
- Fernando Soler
- Departamento de Bioquímica y Biología Molecular A, Universidad de Murcia, Campus de Espinardo, Murcia, Spain
| | | | | |
Collapse
|
12
|
Abstract
The SERCA (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase) is probably the most extensively studied membrane protein transporter. There is a vast array of diverse inhibitors for the Ca2+ pump, and many have proved significant in helping to elucidate both the mechanism of transport and gaining conformational structures. Some SERCA inhibitors such as thapsigargin have been used extensively as pharmacological tools to probe the roles of Ca2+ stores in Ca2+ signalling processes. Furthermore, some inhibitors have been implicated in the cause of diseases associated with endocrine disruption by environmental pollutants, whereas others are being developed as potential anticancer agents. The present review therefore aims to highlight some of the wide range of chemically diverse inhibitors that are known, their mechanisms of action and their binding location on the Ca2+ ATPase. Additionally, some ideas for the future development of more useful isoform-specific inhibitors and anticancer drugs are presented.
Collapse
|
13
|
Tuusa JT, Leskelä TT, Petäjä-Repo UE. Human delta opioid receptor biogenesis is regulated via interactions with SERCA2b and calnexin. FEBS J 2010; 277:2815-29. [PMID: 20528919 DOI: 10.1111/j.1742-4658.2010.07699.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Sarco(endo)plasmic reticulum calcium ATPase (SERCA)2b maintains the cellular Ca(2+) homeostasis by transferring Ca(2+) from the cytosol to the lumen of the endoplasmic reticulum (ER). Recently, SERCA2b has also been shown to be involved in the biosynthesis of secreted and membrane proteins via direct protein-protein interactions, involving components of the ER folding and quality-control machinery, as well as newly synthesized G protein-coupled receptors. Here we demonstrate that the human delta opioid receptor (hdeltaOR) exists in a ternary complex with SERCA2b and the ER molecular chaperone calnexin. The interaction between SERCA2b and hdeltaOR in vivo did not require calnexin as it was independent of the C-terminal calnexin-interacting domain of SERCA2b. However, the receptor was able to mediate co-immunoprecipitation of calnexin with the C-terminally truncated SERCA2b. The association of SERCA2b with hdeltaOR was regulated in vitro by Ca(2+) and ATP in a manner that was opposite to the calnexin-hdeltaOR interaction. Importantly, co-expression of the catalytically inactive SERCA2b(D351A) or calnexin binding-compromised SERCA2bDeltaC mutants with the receptor decreased the expression of mature receptors in a manner that did not directly relate to changes in the ER Ca(2+) concentration. We conclude that dynamic interactions among SERCA2b, calnexin and the hdeltaOR precursor orchestrate receptor biogenesis and are regulated by Ca(2+) and ATP. We further hypothesize that the primary role of SERCA2b in this process is to act as a Ca(2+) sensor in the vicinity of active translocons, integrating protein folding with local fluctuations of ER Ca(2+) levels.
Collapse
Affiliation(s)
- Jussi T Tuusa
- Department of Anatomy and Cell Biology, Institute of Biomedicine, University of Oulu, Oulu, Finland
| | | | | |
Collapse
|
14
|
Hailey DW, Rambold AS, Satpute-Krishnan P, Mitra K, Sougrat R, Kim PK, Lippincott-Schwartz J. Mitochondria supply membranes for autophagosome biogenesis during starvation. Cell 2010; 141:656-67. [PMID: 20478256 DOI: 10.1016/j.cell.2010.04.009] [Citation(s) in RCA: 1021] [Impact Index Per Article: 72.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 02/17/2010] [Accepted: 04/02/2010] [Indexed: 12/13/2022]
Abstract
Starvation-induced autophagosomes engulf cytosol and/or organelles and deliver them to lysosomes for degradation, thereby resupplying depleted nutrients. Despite advances in understanding the molecular basis of this process, the membrane origin of autophagosomes remains unclear. Here, we demonstrate that, in starved cells, the outer membrane of mitochondria participates in autophagosome biogenesis. The early autophagosomal marker, Atg5, transiently localizes to punctae on mitochondria, followed by the late autophagosomal marker, LC3. The tail-anchor of an outer mitochondrial membrane protein also labels autophagosomes and is sufficient to deliver another outer mitochondrial membrane protein, Fis1, to autophagosomes. The fluorescent lipid NBD-PS (converted to NBD-phosphotidylethanolamine in mitochondria) transfers from mitochondria to autophagosomes. Photobleaching reveals membranes of mitochondria and autophagosomes are transiently shared. Disruption of mitochondria/ER connections by mitofusin2 depletion dramatically impairs starvation-induced autophagy. Mitochondria thus play a central role in starvation-induced autophagy, contributing membrane to autophagosomes.
Collapse
Affiliation(s)
- Dale W Hailey
- The Eunice Kennedy Shriver National Institutes of Child Health and Human Development, 18 Library Drive, Bethesda, MD 20892, USA
| | | | | | | | | | | | | |
Collapse
|
15
|
Gramigni E, Tadini-Buoninsegni F, Bartolommei G, Santini G, Chelazzi G, Moncelli MR. Inhibitory effect of Pb2+ on the transport cycle of the Na+,K+-ATPase. Chem Res Toxicol 2010; 22:1699-704. [PMID: 19678672 DOI: 10.1021/tx9001786] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effect of Pb(2+) on the transport cycle of the Na(+),K(+)-ATPase was characterized in detail at a molecular level by combining electrical and biochemical measurements. Electrical measurements were performed by adsorbing purified membrane fragments containing Na(+),K(+)-ATPase on a solid-supported membrane. Upon adsorption, the Na(+),K(+)-ATPase was activated by carrying out concentration jumps of different activating substrates, for example, Na(+) and ATP. Charge movements following Na(+),K(+)-ATPase activation were measured in the presence of various Pb(2+) concentrations to investigate the effect of Pb(2+) on different ion translocating steps of the pump cycle. These charge measurements were then compared to biochemical measurements of ATPase activity in the presence of increasing Pb(2+) concentration. Our results indicate that Pb(2+) inhibits cycling of the enzyme, but it does not affect cytoplasmic Na(+) binding and release of Na(+) ions at the extracellular side at concentrations below 10 muM. To explain the inhibitory effect of Pb(2+) on the Na(+),K(+)-ATPase, we propose that Pb(2+) may interfere with the hydrolytic cleavage of the phosphorylated intermediate E(2)P, which occurs in the K(+)-related branch of the pump cycle.
Collapse
Affiliation(s)
- Elisa Gramigni
- Department of Evolutionary Biology Leo Pardi, University of Florence, 50125 Florence, Italy
| | | | | | | | | | | |
Collapse
|
16
|
Structural basis for the high Ca2+ affinity of the ubiquitous SERCA2b Ca2+ pump. Proc Natl Acad Sci U S A 2009; 106:18533-8. [PMID: 19846779 DOI: 10.1073/pnas.0906797106] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sarco(endo)plasmic reticulum Ca(2+) ATPase (SERCA) Ca(2+) transporters pump cytosolic Ca(2+) into the endoplasmic reticulum, maintaining a Ca(2+) gradient that controls vital cell functions ranging from proliferation to death. To meet the physiological demand of the cell, SERCA activity is regulated by adjusting the affinity for Ca(2+) ions. Of all SERCA isoforms, the housekeeping SERCA2b isoform displays the highest Ca(2+) affinity because of a unique C-terminal extension (2b-tail). Here, an extensive structure-function analysis of SERCA2b mutants and SERCA1a2b chimera revealed how the 2b-tail controls Ca(2+) affinity. Its transmembrane (TM) segment (TM11) and luminal extension functionally cooperate and interact with TM7/TM10 and luminal loops of SERCA2b, respectively. This stabilizes the Ca(2+)-bound E1 conformation and alters Ca(2+)-transport kinetics, which provides the rationale for the higher apparent Ca(2+) affinity. Based on our NMR structure of TM11 and guided by mutagenesis results, a structural model was developed for SERCA2b that supports the proposed 2b-tail mechanism and is reminiscent of the interaction between the alpha- and beta-subunits of Na(+),K(+)-ATPase. The 2b-tail interaction site may represent a novel target to increase the Ca(2+) affinity of malfunctioning SERCA2a in the failing heart to improve contractility.
Collapse
|
17
|
P-type ATPases as drug targets: tools for medicine and science. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:207-20. [PMID: 19388138 DOI: 10.1016/j.bbabio.2008.12.019] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
P-type ATPases catalyze the selective active transport of ions like H+, Na+, K+, Ca2+, Zn2+, and Cu2+ across diverse biological membrane systems. Many members of the P-type ATPase protein family, such as the Na+,K+-, H+,K+-, Ca2+-, and H+-ATPases, are involved in the development of pathophysiological conditions or provide critical function to pathogens. Therefore, they seem to be promising targets for future drugs and novel antifungal agents and herbicides. Here, we review the current knowledge about P-type ATPase inhibitors and their present use as tools in science, medicine, and biotechnology. Recent structural information on a variety of P-type ATPase family members signifies that all P-type ATPases can be expected to share a similar basic structure and a similar basic machinery of ion transport. The ion transport pathway crossing the membrane lipid bilayer is constructed of two access channels leading from either side of the membrane to the ion binding sites at a central cavity. The selective opening and closure of the access channels allows vectorial access/release of ions from the binding sites. Recent structural information along with new homology modeling of diverse P-type ATPases in complex with known ligands demonstrate that the most proficient way for the development of efficient and selective drugs is to target their ion transport pathway.
Collapse
|
18
|
Abstract
The effect of the antimycotic drug clotrimazole (CLT) on the Na,K-ATPase was investigated using fluorescence and electrical measurements. The results obtained by steady-state fluorescence experiments with the electrochromic styryl dye RH421 were combined with those achieved by a pre-steady-state method based on fast solution exchange on a solid supported membrane that adsorbs the protein. Both techniques are suitable for monitoring the electrogenic steps of the pump cycle and are in general complementary, yielding distinct kinetic information. The experiments show clearly that CLT affects specific partial reactions of the pump cycle of the Na,K-ATPase with an affinity in the low micromolar range and in a reversible manner. All results can be consistently explained by proposing the CLT-promoted formation of an ion-occluded-CLT-bound conformational E(2) state, E(2)(CLT)(X(2)) that acts as a "dead-end" side track of the pump cycle, where X stands for H+ or K+. Na+ binding, enzyme phosphorylation, and Na+ transport were not affected by CLT, and at high CLT concentrations approximately (1/3) of the enzyme remained active in the physiological transport mode. The presence of Na+ and K+ destabilized the inactivated form of the Na,K-ATPase.
Collapse
|
19
|
Alterations in Ca2+-buffering in prion-null mice: association with reduced afterhyperpolarizations in CA1 hippocampal neurons. J Neurosci 2008; 28:3877-86. [PMID: 18400886 DOI: 10.1523/jneurosci.0675-08.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Prion protein (PrP) is a normal component of neurons, which confers susceptibility to prion diseases. Despite its evolutionary conservation, its normal function remains controversial. PrP-deficient (Prnp(0/0)) mice have weaker afterhyperpolarizations (AHPs) in cerebellar and hippocampal neurons. Here we show that the AHP impairment in hippocampal CA1 pyramidal cells is selective for the slow AHP, and is not caused by an impairment of either voltage-gated Ca(2+) channels or Ca(2+)-activated K(+) channels. Instead, Prnp(0/0) neurons have twofold to threefold stronger Ca(2+) buffering and double the Ca(2+) extrusion rate. In Prnp(0/0) neurons thapsigargin abolished the stronger Ca(2+) buffering and extrusion, and thapsigargin or cyclopiazonic acid abolished the weakening of the slow AHPs. These data implicate sarcoplasmic/endoplasmic reticulum calcium ATPase in the enhanced Ca(2+) buffering, and extrusion into the endoplasmic reticulum, which contains substantial amounts of PrP in wild-type mice. Altered Ca(2+) homeostasis can explain several phenotypes identified in Prnp(0/0) mice.
Collapse
|