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1.
Res Involv Engagem ; 7(1): 40, 2021 Jun 14.
Article in English | MEDLINE | ID: mdl-34127076

ABSTRACT

BACKGROUND: England operates a National Data Opt-Out (NDOO) for the secondary use of confidential health data for research and planning. We hypothesised that public awareness and support for the secondary use of health data and the NDOO would vary by participant demography and healthcare experience. We explored patient/public awareness and perceptions of secondary data use, grouping potential researchers into National Health Service (NHS), academia or commercial. We assessed awareness of the NDOO system amongst patients, carers, healthcare staff and the public. We co-developed recommendations to consider when sharing unconsented health data for research. METHODS: A patient and public engagement program, co-created and including patient and public workshops, questionnaires and discussion groups regarding anonymised health data use. RESULTS: There were 350 participants in total. Central concerns for health data use included unauthorised data re-use, the potential for discrimination and data sharing without patient benefit. 94% of respondents were happy for their data to be used for NHS research, 85% for academic research and 68% by health companies, but less than 50% for non-healthcare companies and opinions varied with demography and participant group. Questionnaires showed that knowledge of the NDOO was low, with 32% of all respondents, 53% of all NHS staff and 29% of all patients aware of the NDOO. Recommendations to guide unconsented secondary health data use included that health data use should benefit patients; data sharing decisions should involve patients/public. That data should remain in close proximity to health services with the principles of data minimisation applied. Further, that there should be transparency in secondary health data use, including publicly available lists of projects, summaries and benefits. Finally, organisations involved in data access decisions should participate in programmes to increase knowledge of the NDOO, to ensure public members were making informed choices about their own data. CONCLUSION: The majority of participants in this study reported that the use of healthcare data for secondary purposes was acceptable when accessed by NHS. Academic and health-focused companies. However, awareness was limited, including of the NDOO. Further development of publicly-agreed recommendations for secondary health data use may improve both awareness and confidence in secondary health data use.


Health data from routine care can be pseudonymised (with a link remaining to the patient but identifying features removed) or anonymised (with identifying features removed and the link to the patient severed) and used for research and health planning; termed "secondary use". The National Health Service (NHS) is a single publicly-funded health service for the United Kingdom (UK). The NHS supports secondary data use with a National Data opt-out system. The potential benefits of data secondary use are clear but concerns have been raised. Although the Data Opt-Out is publicised, it is unclear how much public awareness there is of this scheme. We report a patient and publicly created and delivered series of activities including > 350 people; with young adults, patients, NHS staff and the public; to assess concerns, knowledge and acceptance of data sharing.Perceptions of and support for secondary health data use varied depending on who was asked (by age, gender) and their experience of health services (Staff member, patient, member of the public). Knowledge of schemes to limit secondary data use (such as the UK National Data Op-Out) was low, even among NHS staff. The main concerns of sharing health data included onward data use, the potential for discrimination and exploitation and commercial gain from data use with no benefit to patients. Despite this, most participants agreed with health data sharing with NHS, academic and commercial health-based entities. Agreed, co-created themes to increase the acceptability of health data secondary use included education about 'Opt-out' schemes, health service oversight of data use (as the most trusted partner), public and patient involvement in data sharing decisions and public transparency.

2.
Thorax ; 60(1): 55-9, 2005 Jan.
Article in English | MEDLINE | ID: mdl-15618584

ABSTRACT

BACKGROUND: Most patients with cystic fibrosis (CF) have a DeltaF508 mutation resulting in abnormal retention of mutant gene protein (DeltaF508-CFTR) within the cell. This study was undertaken to investigate DeltaF508-CFTR trafficking in native cells from patients with CF with the aim of discovering pharmacological agents that can move DeltaF508-CFTR to its correct location in the apical cell membrane. METHOD: Nasal epithelial cells were obtained by brushing from individuals with CF. CFTR location was determined using immunofluorescence and confocal imaging in untreated cells and cells treated with sildenafil. The effect of sildenafil treatment on CFTR chloride transport function was measured in CF15 cells using an iodide efflux assay. RESULTS: In most untreated CF cells DeltaF508-CFTR was mislocalised within the cell at a site close to the nucleus. Exposure of cells to sildenafil (2 hours at 37 degrees C) resulted in recruitment of DeltaF508-CFTR to the apical membrane and the appearance of chloride transport activity. Sildenafil also increased DeltaF508-CFTR trafficking in cells from individuals with CF with a single copy DeltaF508 (DeltaF508/4016ins) or with a newly described CF trafficking mutation (R1283M). CONCLUSIONS: The findings provide proof of principle for sildenafil as a DeltaF508-CFTR trafficking drug and give encouragement for future testing of sildenafil and related PDE5 inhibitors in patients with CF.


Subject(s)
Cystic Fibrosis Transmembrane Conductance Regulator/drug effects , Cystic Fibrosis/metabolism , Phosphodiesterase Inhibitors/pharmacology , Piperazines/pharmacology , Adolescent , Adult , Biological Transport/drug effects , Biological Transport/genetics , Child , Child, Preschool , Chlorides/metabolism , Cystic Fibrosis/genetics , Cystic Fibrosis Transmembrane Conductance Regulator/genetics , Cystic Fibrosis Transmembrane Conductance Regulator/metabolism , Epithelial Cells/metabolism , Fluorescent Antibody Technique , Humans , Infant , Mutation/genetics , Nose , Purines , Respiratory Mucosa , Sildenafil Citrate , Sulfones
3.
Br J Cancer ; 91(6): 1149-54, 2004 Sep 13.
Article in English | MEDLINE | ID: mdl-15328519

ABSTRACT

The antiangiogenic factor METH-2 (ADAMTS-8) was identified in a previous dual-channel cDNA microarray analysis to be at least two-fold under-represented in 85% (28 out of 33) of primary non-small-cell lung carcinomas (NSCLCs). This observation has been validated in an independent series of NSCLCs and adjacent normal tissues by comparative multiplex RT-PCR, and METH-2 mRNA expression was dramatically reduced in all 23 tumour samples analysed. Immunohistochemical analysis of the same sample set demonstrated that METH-2 was strongly expressed in 14 out of 19 normal epithelial sites examined but only one out of 20 NSCLCs. DNA methylation analysis of the proximal promoter region of this gene revealed abnormal hypermethylation in 67% of the adenocarcinomas and 50% of squamous cell carcinomas, indicating that epigenetic mechanisms are involved in silencing this gene in NSCLC. No homozygous deletions of METH-2 were found in lung cancer cell lines. Allelic imbalance in METH-2 was assessed by an intronic single nucleotide polymorphism (SNP) assay and observed in 44% of informative primary samples. In conclusion, the downregulation of METH-2 expression in primary NSCLC, often associated with promoter hypermethylation, is a frequent event, which may be related to the development of the disease.


Subject(s)
Carcinoma, Non-Small-Cell Lung/genetics , Gene Silencing , Lung Neoplasms/genetics , Metalloendopeptidases/genetics , Promoter Regions, Genetic/genetics , ADAM Proteins , ADAMTS Proteins , Adenocarcinoma/genetics , Aged , Carcinoma, Squamous Cell/genetics , DNA Methylation , DNA, Neoplasm/genetics , Gene Expression Regulation, Neoplastic/genetics , Humans , Middle Aged , RNA, Messenger/genetics , Reverse Transcriptase Polymerase Chain Reaction
4.
J Cell Sci ; 114(Pt 22): 4073-81, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11739639

ABSTRACT

A number of genetic diseases, including cystic fibrosis, have been identified as disorders of protein trafficking associated with retention of mutant protein within the endoplasmic reticulum. In the presence of the benzo(c)quinolizinium drugs, MPB-07 and its congener MPB-91, we show the activation of cystic fibrosis transmembrane conductance regulator (CFTR) delF508 channels in IB3-1 human cells, which express endogenous levels of delF508-CFTR. These drugs were without effect on the Ca(2+)-activated Cl- transport, whereas the swelling-activated Cl- transport was found altered in MPB-treated cells. Immunoprecipitation and in vitro phosphorylation shows a 20% increase of the band C form of delF508 after MPB treatment. We then investigated the effect of these drugs on the extent of mislocalisation of delF508-CFTR in native airway cells from cystic fibrosis patients. We first showed that delF508 CFTR was characteristically restricted to an endoplasmic reticulum location in approximately 80% of untreated cells from CF patients homozygous for the delF508-CFTR mutation. By contrast, 60-70% of cells from non-CF patients showed wild-type CFTR in an apical location. MPB-07 treatment caused dramatic relocation of delF508-CFTR to the apical region such that the majority of delF508/delF508 CF cells showed a similar CFTR location to that of wild-type. MPB-07 had no apparent effect on the distribution of wild-type CFTR, the apical membrane protein CD59 or the ER membrane Ca(2+),Mg-ATPase. We also showed a similar pharmacological effect in nasal cells freshly isolated from a delF508/G551D CF patient. The results demonstrate selective redirection of a mutant membrane protein using cell-permeant small molecules of the benzo(c)quinolizinium family and provide a major advance towards development of a targetted drug treatment for cystic fibrosis and other disorders of protein trafficking.


Subject(s)
Chlorides/metabolism , Cystic Fibrosis Transmembrane Conductance Regulator/metabolism , Cystic Fibrosis/metabolism , Quinolizines/pharmacology , Respiratory Mucosa/drug effects , Calcium/metabolism , Cell Polarity , Cells, Cultured , Cyclic AMP/agonists , Cyclic AMP/metabolism , Cystic Fibrosis/genetics , Cystic Fibrosis Transmembrane Conductance Regulator/genetics , Enzyme Inhibitors/pharmacology , Humans , Immunohistochemistry , Iodides/metabolism , Quinolizines/chemistry , Respiratory Mucosa/cytology , Respiratory Mucosa/metabolism
5.
Pflugers Arch ; 443 Suppl 1: S117-20, 2001.
Article in English | MEDLINE | ID: mdl-11845316

ABSTRACT

Wild-type and the DeltaF508 mutation of the cystic fibrosis transmembrane conductance regulator (DeltaF508-CFTR) were localised by confocal imaging in DeltaF508/DeltaF508 native airway epithelial cells using a well-characterised CFTR antibody. Surface nasal epithelial cells from three control and three CF individuals were obtained from nasal brushings. Cells were fixed, permeabilised and incubated with first antibody for 18 h at 4 degrees C. Following labelling with second antibody, cells were viewed with the confocal microscope. Wild-type CFTR was localised predominantly apically, whereas DeltaF508-CFTR was located mainly inside the cell in a region close to the nucleus. Incubation of cells with MPB-07 (250 microM) at 37 degrees C for 2 h resulted in pronounced movement of DeltaF508-CFTR to the cell periphery, but did not change the localisation of wild-type CFTR. The results show that DeltaF508-CFTR is mislocalised in native nasal epithelial cells and that its distribution is altered in response to the new CFTR activator, MPB-07. The findings should lead to development of a rational drug treatment for CF patients carrying the DeltaF508 mutation.


Subject(s)
Cystic Fibrosis Transmembrane Conductance Regulator/analysis , Epithelial Cells/chemistry , Nasal Mucosa/chemistry , Antibody Specificity , Cystic Fibrosis/metabolism , Cystic Fibrosis Transmembrane Conductance Regulator/immunology , Humans , Microscopy, Confocal , Nasal Mucosa/cytology
6.
Pflugers Arch ; 443 Suppl 1: S121-6, 2001.
Article in English | MEDLINE | ID: mdl-11845317

ABSTRACT

The cystic fibrosis transmembrane conductance regulator (CFTR) mediates secretion of mucins and serous proteins. The aim was to correct pharmacologically the CFTR defect in protein secretion in airway gland cells and so to correct the viscous mucous secretions in cystic fibrosis (CF) airways and lungs. The strategies tested included direct activation of CFTR, bypass of CFTR-mediated protein secretion and movement of the mutated form of CFTR (DeltaF(508)-CFTR) to the cell membrane. Compounds related to 3-isobutyl-1-methylxanthine (IBMX), including a selective type-IV phosphodiesterase inhibitor and the adenosine receptor antagonists 8-cyclopentyltheophylline (CPT) and 8-cyclopentyl-1,3-dipropylxanthine (CPX), corrected the defective beta-adrenergic stimulation of mucin secretion in CFTR antibody-inhibited submandibular gland cells. CPT also corrected lactoferrin secretion in DeltaF(508)/DeltaF(508)-CFTR nasal gland cells. The data suggest that correction of CFTR protein secretion activity is not mediated by excessive increase in cyclic AMP, involves direct interaction with CFTR but does not require increase in CFTR Cl(-) channel activity. Regulated glycoprotein secretion was characterised in the airway gland cell line Calu-3 to investigate whether a CFTR bypass is present. Studies of DeltaF(508)-CFTR trafficking using confocal imaging showed that some DeltaF(508)-CFTR colocalised with the apical membrane protein CD59; however a large amount was mislocalised within the cell. The results showing pharmacological correction of the defective CFTR-mediated protein secretion afford promise for the development of a rational drug therapy for CF patients.


Subject(s)
Cyclic AMP/analogs & derivatives , Cyclic AMP/pharmacology , Cystic Fibrosis Transmembrane Conductance Regulator/metabolism , Cystic Fibrosis/drug therapy , Cystic Fibrosis/metabolism , Enzyme Inhibitors/pharmacology , Theophylline/analogs & derivatives , Thionucleotides/pharmacology , Adrenergic beta-Agonists/pharmacology , Animals , Cell Line , Cystic Fibrosis Transmembrane Conductance Regulator/analysis , Humans , Isoproterenol/pharmacology , Lactoferrin/metabolism , Mucins/metabolism , Nasal Mucosa/chemistry , Nasal Mucosa/metabolism , Rats , Submandibular Gland/metabolism , Theophylline/pharmacology
7.
Am J Physiol Cell Physiol ; 279(6): C1925-37, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11078708

ABSTRACT

The pharmacological activation of the cystic fibrosis gene protein cystic fibrosis transmembrane conductance regulator (CFTR) was studied in human airway epithelial Calu-3 cells, which express a high level of CFTR protein as assessed by Western blot and in vitro phosphorylation. Immunolocalization shows that CFTR is located in the apical membrane. We performed iodide efflux, whole cell patch-clamp, and short-circuit recordings to demonstrate that the novel synthesized xanthine derivative 3, 7-dimethyl-1-isobutylxanthine (X-33) is an activator of the CFTR channel in Calu-3 cells. Whole cell current activated by X-33 or IBMX is linear, inhibited by glibenclamide and diphenylamine-2-carboxylate but not by DIDS or TS-TM calix[4]arene. Intracellular cAMP was not affected by X-33. An outwardly rectifying Cl(-) current was recorded in the absence of cAMP and X-33 stimulation, inhibited by DIDS and TS-TM calix[4]arene. With the use of short-circuit recordings, X-33 and IBMX were able to stimulate a large concentration-dependent CFTR transport that was blocked by glibenclamide but not by DIDS. Our results show that manipulating the chemical structure of xanthine derivatives offers an opportunity to identify further specific activators of CFTR in airway cells.


Subject(s)
Cystic Fibrosis Transmembrane Conductance Regulator/metabolism , Respiratory Mucosa/cytology , Respiratory Mucosa/drug effects , Theophylline/analogs & derivatives , Xanthines/pharmacology , 1-Methyl-3-isobutylxanthine/pharmacology , 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid/pharmacology , Animals , Biological Transport/drug effects , Biological Transport/physiology , CHO Cells , Caffeine/pharmacology , Calcium Channel Blockers/pharmacology , Chlorides/metabolism , Colforsin/pharmacology , Cricetinae , Cyclic AMP/metabolism , Dose-Response Relationship, Drug , Glyburide/pharmacology , Hypoglycemic Agents/pharmacology , In Vitro Techniques , Iodides/pharmacokinetics , Iodine Radioisotopes , Membrane Potentials/drug effects , Membrane Potentials/physiology , Membrane Proteins/metabolism , Patch-Clamp Techniques , Phosphodiesterase Inhibitors/pharmacology , Phosphorylation , Respiratory Mucosa/physiology , Theophylline/pharmacology , Xanthines/chemical synthesis , ortho-Aminobenzoates/pharmacology
8.
FEBS Lett ; 464(1-2): 48-52, 1999 Dec 24.
Article in English | MEDLINE | ID: mdl-10611481

ABSTRACT

A selective cyclic nucleotide PDE5 inhibitor corrected the defective mucin secretion response to the beta-agonist isoproterenol in submandibular acinar cells inhibited by antibody directed against the cystic fibrosis transmembrane conductance regulator. The PDE5 inhibitor was as effective as cpt-cyclic AMP or a selective PDE4 inhibitor. However, the PDE5 inhibitor had no effect on basal or isoproterenol-stimulated cyclic AMP levels and did not stimulate mucin secretion. The results showing, for the first time, correction of the CFTR mucin secretion defect by a PDE5 inhibitor, which may involve cyclic GMP, will have a major impact in development of a rational drug treatment for cystic fibrosis.


Subject(s)
3',5'-Cyclic-GMP Phosphodiesterases/antagonists & inhibitors , Cystic Fibrosis Transmembrane Conductance Regulator/immunology , Mucins/metabolism , Submandibular Gland/metabolism , 1-Methyl-3-isobutylxanthine/pharmacology , Animals , Antibodies/pharmacology , Cyclic AMP/metabolism , Cyclic GMP/metabolism , Cyclic Nucleotide Phosphodiesterases, Type 5 , Cystic Fibrosis Transmembrane Conductance Regulator/physiology , Humans , Isoproterenol/pharmacology , Mucins/drug effects , Purinones/pharmacology , Pyridazines/pharmacology , Pyridines/pharmacology , Rats , Rolipram/pharmacology , Submandibular Gland/drug effects
9.
J Biol Chem ; 274(39): 27415-25, 1999 Sep 24.
Article in English | MEDLINE | ID: mdl-10488073

ABSTRACT

Chloride channels play an important role in the physiology and pathophysiology of epithelia, but their pharmacology is still poorly developed. We have chemically synthesized a series of substituted benzo[c]quinolizinium (MPB) compounds. Among them, 6-hydroxy-7-chlorobenzo[c]quinolizinium (MPB-27) and 6-hydroxy-10-chlorobenzo[c]quinolizinium (MPB-07), which we show to be potent and selective activators of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. We examined the effect of MPB compounds on the activity of CFTR channels in a variety of established epithelial and nonepithelial cell systems. Using the iodide efflux technique, we show that MPB compounds activate CFTR chloride channels in Chinese hamster ovary (CHO) cells stably expressing CFTR but not in CHO cells lacking CFTR. Single and whole cell patch clamp recordings from CHO cells confirm that CFTR is the only channel activated by the drugs. Ussing chamber experiments reveal that the apical addition of MPB to human nasal epithelial cells produces a large increase of the short circuit current. This current can be totally inhibited by glibenclamide. Whole cell experiments performed on native respiratory cells isolated from wild type and CF null mice also show that MPB compounds specifically activate CFTR channels. The activation of CFTR by MPB compounds was glibenclamide-sensitive and 4, 4'-diisothiocyanostilbene-2,2'-disulfonic acid-insensitive. In the human tracheal gland cell line MM39, MPB drugs activate CFTR channels and stimulate the secretion of the antibacterial secretory leukoproteinase inhibitor. In submandibular acinar cells, MPB compounds slightly stimulate CFTR-mediated submandibular mucin secretion without changing intracellular cAMP and ATP levels. Similarly, in CHO cells MPB compounds have no effect on the intracellular levels of cAMP and ATP or on the activity of various protein phosphatases (PP1, PP2A, PP2C, or alkaline phosphatase). Our results provide evidence that substituted benzo[c]quinolizinium compounds are a novel family of activators of CFTR and of CFTR-mediated protein secretion and therefore represent a new tool to study CFTR-mediated chloride and secretory functions in epithelial tissues.


Subject(s)
Cystic Fibrosis Transmembrane Conductance Regulator/drug effects , Quinolizines/pharmacology , Animals , CHO Cells , Cilia/drug effects , Cilia/physiology , Colforsin/pharmacology , Cricetinae , Cystic Fibrosis Transmembrane Conductance Regulator/deficiency , Cystic Fibrosis Transmembrane Conductance Regulator/physiology , Drug Design , Female , Glyburide/pharmacology , Humans , Male , Membrane Potentials/drug effects , Mice , Mice, Inbred BALB C , Mice, Knockout , Molecular Structure , Nasal Mucosa/drug effects , Nasal Mucosa/physiology , Patch-Clamp Techniques , Quinolines/chemical synthesis , Quinolines/chemistry , Quinolines/pharmacology , Quinolizines/chemical synthesis , Quinolizines/chemistry , Recombinant Proteins/drug effects , Recombinant Proteins/metabolism , Structure-Activity Relationship , Transfection
10.
Br J Pharmacol ; 125(4): 697-704, 1998 Oct.
Article in English | MEDLINE | ID: mdl-9831904

ABSTRACT

1. The cystic fibrosis gene protein, the cystic fibrosis transmembrane conductance regulator (CFTR) acts as a chloride channel and is a key regulator of mucin secretion. The mechanism by which 3-isobutyl-1-methylxanthine (IBMX) corrects the defect in CFTR mediated beta-adrenergic stimulation of mucin secretion has not been determined. The present study has investigated the actions of adenosine A1 and A2 receptor antagonists to determine whether ability to stimulate mucin secretion correlates with correction of CFTR antibody inhibited beta-adrenergic response and whether excessive cyclic AMP rise is required. 2. CFTR antibodies were introduced into living rat submandibular acini by hypotonic swelling. Following recovery, mucin secretion in response to isoproterenol was measured. 3. The adenosine A1 receptor antagonist, 8 cyclopentyltheophylline (CPT) was a less potent stimulator of mucin secretion than was the A2 receptor antagonist dimethylpropargylxanthine (DMPX). A concentration of CPT close to the Ki for A1 receptor antagonism (10 nM) did not stimulate mucin secretion. 4. DMPX, although a potent stimulator of mucin secretion, did not correct CFTR antibody inhibited mucin secretion. 5. CPT corrected defective CFTR antibody inhibited mucin secretion at a high (1 mM) concentration, suggesting a mechanism other than adenosine receptor antagonism. 6. DMPX potentiated the isoproterenol induced cyclic AMP rise, whereas CPT did not. 7. Correction of the defective CFTR mucin secretion response did not correlate with ability to stimulate mucin secretion and did not require potentiation of beta-adrenergic induced increases in cyclic AMP. This affords real promise for the development of a selective drug treatment for cystic fibrosis.


Subject(s)
Cyclic AMP/metabolism , Cystic Fibrosis Transmembrane Conductance Regulator/pharmacology , Mucins/metabolism , Purinergic P1 Receptor Antagonists , Receptors, Adrenergic, beta/drug effects , 1-Methyl-3-isobutylxanthine/chemistry , 1-Methyl-3-isobutylxanthine/pharmacology , Animals , Antibodies/pharmacology , Chromatography, Gel , Cystic Fibrosis Transmembrane Conductance Regulator/immunology , Dose-Response Relationship, Drug , Electrophoresis, Cellulose Acetate , Mucins/drug effects , Phosphorylation , Precipitin Tests , Rats , Submandibular Gland/drug effects , Submandibular Gland/physiology , Theobromine/analogs & derivatives , Theobromine/chemistry , Theobromine/pharmacology , Theophylline/analogs & derivatives , Theophylline/chemistry , Theophylline/pharmacology
15.
Biochem Biophys Res Commun ; 215(2): 674-81, 1995 Oct 13.
Article in English | MEDLINE | ID: mdl-7488008

ABSTRACT

beta-adrenergic stimulation of glycoprotein secretion was shown to be decreased in submandibular glands of Cystic Fibrosis (CF) mice. The defective response was partially restored by the methylxanthine, IBMX or cpt-cyclic AMP. Cholinergic stimulation of pancreatic amylase secretion was not affected in CF mice, demonstrating that this is not a generalised depression of protein secretion. The data are the first to show that the CF mouse mimics the protein secretion defect in CF human submandibular cells and that the mechanism of correction of the CF defect is via elevation of cyclic AMP. The results are therefore invaluable towards devising a rational pharmaceutical therapy for CF patients.


Subject(s)
1-Methyl-3-isobutylxanthine/pharmacology , Adrenergic beta-Agonists/pharmacology , Carbachol/pharmacology , Cystic Fibrosis/metabolism , Glycoproteins/biosynthesis , Submandibular Gland/metabolism , Amylases/metabolism , Animals , Cyclic AMP/analogs & derivatives , Cyclic AMP/metabolism , Cyclic AMP/pharmacology , Glucosamine/metabolism , Heterozygote , Humans , Male , Mice , Mice, Mutant Strains , Pancreas/drug effects , Pancreas/enzymology , Submandibular Gland/drug effects , Thionucleotides/pharmacology
16.
Biochim Biophys Acta ; 1233(1): 1-6, 1995 Jan 26.
Article in English | MEDLINE | ID: mdl-7833344

ABSTRACT

Pancreatic rough ER ATP-binding proteins, including two isoforms of SERCA-2b Ca2+,Mg-ATPase, were identified using specific photoaffinity labelling with 8-azido-ATP. 8-Azido-ATP irreversibly inhibited Ca2+,Mg-ATPase activity only after UV irradiation and the inhibition was prevented by inclusion of 5 mM ATP in the labelling reaction. Rough ER proteins of apparent molecular masses 141, 111, 100, 84, 69, 55 and 47 kDa were detected following photoaffinity-labelling with 8-azido-[alpha-32P]ATP. The two bands at 111 kDa and 100 kDa corresponded in molecular mass to the two SERCA-2b Ca2+,Mg-ATPase isoforms previously demonstrated immunologically [1]. Immunoprecipitation of rough ER proteins by a SERCA-2b-specific antibody showed that the two ATPase bands were photoaffinity-labelled. Photoaffinity labelling of the 111 and 100 kDa proteins was: (a) abolished when Ca2+,Mg-ATPase activity was inactivated by EDTA-treatment of rough ER membranes; (b) inhibited by the Ca2+,Mg-ATPase inhibitor vanadate; (c) not affected by thapsigargin. The data demonstrate that pancreatic rough ER contains two isoforms of the SERCA-2b Ca2+,Mg-ATPase whose ATP-binding properties are susceptible to inhibition by vanadate but not thapsigargin.


Subject(s)
Adenosine Triphosphate/metabolism , Ca(2+) Mg(2+)-ATPase/metabolism , Endoplasmic Reticulum/enzymology , Isoenzymes/metabolism , Pancreas/enzymology , Adenosine Triphosphate/analogs & derivatives , Affinity Labels , Animals , Azides , Binding Sites , Ca(2+) Mg(2+)-ATPase/antagonists & inhibitors , In Vitro Techniques , Photochemistry , Precipitin Tests , Rats , Rats, Wistar
17.
Anal Biochem ; 221(1): 173-81, 1994 Aug 15.
Article in English | MEDLINE | ID: mdl-7985790

ABSTRACT

The Ca(2+)-activated photoprotein aequorin has been engineered with the endoplasmic reticulum (ER)-targeting sequence from calreticulin at the N-terminus and the KDEL sequence at the C-terminus so that it locates in the ER of living cells. Targeting of apoaequorin to the ER of COS7 cells was demonstrated by immunolocalization. Selective permeabilization of cells expressing the modified protein suggested that targeting was highly efficient. Functional photoprotein was reconstituted in live cells by incubating them with coelenterazine. Light emission from cells expressing ER aequorin showed that the estimated free Ca2+ within the ER of live cells at 37 degrees C was 0.3-1.0 microM, some 10 times that in the cytosol. An increase in the rate constant for aequorin light emission was demonstrated when the cells were warmed from 4 degrees C. This increase could be in part, but not wholly, explained by an increase in rate constants for aequorin at higher temperatures and a change in kinetics as a result of the ER targeting of aequorin. The increase in rate constants in the cells was inhibited by thapsigargin and occurred in the presence or absence of extracellular Ca2+. These results highlight the importance of converting aequorin light emission to rate constants and of calibrating any variants if qualitative and quantitative conclusions are to be drawn about free Ca2+ in intracellular compartments.


Subject(s)
Aequorin , Calcium/metabolism , Endoplasmic Reticulum/metabolism , Amino Acid Sequence , Animals , Base Sequence , Cells, Cultured , Luminescent Measurements , Molecular Sequence Data , Protein Engineering , Temperature , Terpenes/pharmacology , Thapsigargin
19.
Biochim Biophys Acta ; 1152(2): 225-30, 1993 Nov 07.
Article in English | MEDLINE | ID: mdl-8218323

ABSTRACT

An antibody raised against a 12 amino acid peptide corresponding to the C-terminal sequence of the SERCA-2b Ca2+,Mg(2+)-ATPase precipitated Ca2+,Mg(2+)-ATPase activity from pancreatic rough ER. Thapsigargin and vanadate inhibited the activity with the same concentration-dependence as for native ER membranes. Partial purification of Ca2+,Mg(2+)-ATPase using Reactive Dye-agarose affinity chromatography resulted in activation of the enzyme, suggesting the presence of an endogenous inhibitor which was detached by binding to the Reactive Dye. Immunoblots and analysis of immunoprecipitated protein revealed two bands of molecular masses approx. 111 kDa and 97 kDa. It is concluded that pancreatic ER Ca2+,Mg(2+)-ATPase is of the SERCA-2b type and consists of two isoforms.


Subject(s)
Ca(2+) Mg(2+)-ATPase/isolation & purification , Endoplasmic Reticulum/enzymology , Isoenzymes/isolation & purification , Pancreas/enzymology , Amino Acid Sequence , Animals , Antibody Specificity , Ca(2+) Mg(2+)-ATPase/genetics , Ca(2+) Mg(2+)-ATPase/immunology , Cross Reactions , Immunoblotting , Isoenzymes/genetics , Isoenzymes/immunology , Molecular Sequence Data , Precipitin Tests , Rats , Rats, Wistar , Terpenes/pharmacology , Thapsigargin , Vanadates/pharmacology
20.
Biochem J ; 293 ( Pt 3): 691-5, 1993 Aug 01.
Article in English | MEDLINE | ID: mdl-8102525

ABSTRACT

Increases in cytoplasmic free Ca2+ concentration in rat submandibular acini were observed in response to isoprenaline (10 microM), noradrenaline (10 microM) and carbamoylcholine (10 microM). Noradrenaline and carbamoylcholine responses were decreased to 27% and 33% respectively in the absence of extracellular Ca2+, suggesting a major requirement for Ca2+ entry. beta-Adrenergic stimulation elicited a small (35-40 nM) free Ca2+ rise, approx. 75% of which was mobilized from an intracellular store. Results suggest that this Ca2+ rise is a key event in the physiological triggering of mucin secretion by exocytosis.


Subject(s)
Calcium/metabolism , Receptors, Adrenergic, beta/physiology , Submandibular Gland/metabolism , Adrenergic beta-Agonists/pharmacology , Adrenergic beta-Antagonists/pharmacology , Animals , Cyclic AMP/metabolism , Homeostasis , Inositol 1,4,5-Trisphosphate/metabolism , Male , Mucins/metabolism , Rats , Rats, Wistar , Submandibular Gland/drug effects
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