Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We demonstrate here that coexpression of ROMK2, an inwardly rectifying ATP-sensitive renal K+ channel (IKATP) with cystic fibrosis transmembrane regulator (CFTR) significantly enhances the sensitivity of ROMK2 to the sulfonylurea compound glibenclamide. When expressed alone, ROMK2 is relatively insensitive to glibenclamide. The interaction between ROMK2, CFTR, and glibenclamide is modulated by altering the phosphorylation state of either ROMK2, CFTR, or an associated protein, as exogenous MgATP and the catalytic subunit of protein kinase A significantly attenuate the inhibitory effect of glibenclamide on ROMK2. Thus CFTR, which has been demonstrated to interact with both Na+ and Cl- channels in airway epithelium, modulates the function of renal ROMK2 K+ channels.
...
PMID:Sensitivity of a renal K+ channel (ROMK2) to the inhibitory sulfonylurea compound glibenclamide is enhanced by coexpression with the ATP-binding cassette transporter cystic fibrosis transmembrane regulator. 875 7

Many heterologously expressed mutants of the cystic fibrosis transmembrane conductance regulator (CFTR) exhibit residual chloride channel activity that can be stimulated by agonists of the adenylate cyclase/protein kinase A pathway. Because of clinical implications for cystic fibrosis of activating mutants in vivo, we are investigating whether deltaF508, the most common disease-associated CFTR mutation, can be activated in airway epithelial cells. We have found that, 36Cl- efflux can be stimulated 19-61% above baseline by beta-adrenoreceptor agonists and cGI-phosphodiesterase inhibitors in transformed nasal polyp (CF-T43) cells homozygous for the deltaF508 mutation. The increase in 36Cl- permeability is diminished by protein kinase A inhibitors and is not mediated by an increase in intracellular calcium concentrations. Preincubation of CF-T43 cells with CFTR anti-sense oligonucleotides prevented an increase in 36Cl- efflux in response to beta-agonist and phosphodiesterase inhibitor. Primary cells isolated from CF nasal polyps gave similar results. These data indicate that endogenous levels of deltaF508 protein can be stimulated to increase 36Cl- permeability in airway epithelial cells.
...
PMID:Activation of endogenous deltaF508 cystic fibrosis transmembrane conductance regulator by phosphodiesterase inhibition. 875 64

The cystic fibrosis transmembrane conductance regulator (CFTR) consists of five domains, two transmembrane-spanning domains, each composed of six transmembrane segments, a regulatory domain, and two nucleotide-binding domains (NBDs). CFTR is expressed in kidney, but its role in overall renal function is not well understood, because mutations in CFTR found in patients with cystic fibrosis are not associated with renal dysfunction. To learn more about the distribution and functional forms of CFTR in kidney, we used a combination of molecular, cell biological, and electrophysiological approaches. These include an evaluation of CFTR mRNA and protein expression, as well as both two-electrode and patch clamping of CFTR expressed either in Xenopus oocytes or mammalian cells. In addition to wild-type CFTR mRNA, an alternate form containing only the first transmembrane domain (TMD), the first NBD, and the regulatory domain (TNR-CFTR) is expressed in kidney. Although missing the second set of TMDs and the second NBD, when expressed in Xenopus oocytes, TNR-CFTR has cAMP-dependent protein kinase A (PKA)-stimulated single Cl- channel characteristics and regulation of PKA activation of outwardly rectifying Cl- channels that are very similar to those of wild-type CFTR. TNR-CFTR mRNA is produced by an unusual mRNA processing mechanism and is expressed in a tissue-specific manner primarily in renal medulla.
...
PMID:Both the wild type and a functional isoform of CFTR are expressed in kidney. 876 23

The cystic fibrosis transmembrane regulator (CFTR) is a Cl- channel regulated by adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase A. A cAMP-independent activation has been recently shown for the protein tyrosine kinase inhibitor genistein in CFTR-transfected NIH/3T3 fibroblasts. We further studied the role of genistein on Cl- secretion in HT-29/B6 and T84 colonic epithelial cells, which express native CFTR in their apical membranes. Transepithelial Cl- secretion was more effectively stimulated in T84 cells when compared with HT-29/B6 cells by mucosal perfusion with 50 microM genistein. Genistein, like the cAMP agonist forskolin, stimulated CFTR activity in cell-attached patches of single cells with similar slope conductances of 8.5 +/- 0.5 and 9.2 +/- 0.3 pS, respectively. Monolayers in Ussing chambers were basolaterally permeabilized with the pore former alpha-toxin, and gradient-driven Cl- current across the apical membrane (ICl) was measured. ICl was stimulated by serosal (i.e., cytosolic) cAMP (half-maximal stimulatory concentration = 9.8 +/- 1.9 microM). In the presence of cAMP (> 5 microM), subsequent mucosal, but not serosal, addition of genistein further increased Icl by approximately 16%; in the absence of cytosolic cAMP, genistein had no effect on ICl. The inactive analogue daidzein had no effect. When cAMP agonists were removed in the continued presence of genistein, ICl remained elevated in both permeabilized and intact monolayers as well as in cell-attached patches of single cells. In addition, genistein blocked K- currents across the basolateral membrane in apically amphotericin B-permeabilized monolayers (half maximal inhibitory concentration = 44.2 +/- 8.1 microM). Therefore, in intact epithelia, the overall secretory response to genistein is composed of stimulatory effects on the apical CFTR and inhibitory effects on the basolateral K+ conductance. We propose that genistein blocks a phosphatase, which regulates CFTR during cAMP-dependent stimulation.
...
PMID:Alternate stimulation of apical CFTR by genistein in epithelia. 877 53

Cystic fibrosis (CF), the most common fatal hereditary disorder in Caucasians, is caused by mutations of the CF transmembrane conductance regulator (CFTR) gene. The protein product encoded by the CFTR gene is a cyclic-AMP-regulated Cl- channel that is dependent on protein kinase phosphorylation and requires binding of ATP for channel opening, but may have additional functions. Although the most common mutation of the CFTR gene (DeltaF508) is found in approximately 70% of CF chromosomes, more than 400 other mutations of the gene have been documented. Several new therapeutic approaches including gene therapy by transfer of the normal CFTR gene to airway epithelium and protein replacement by reconstituting a recombinant functional CFTR protein into the membrane lipid bilayer are being extensively pursued.
...
PMID:[Cystic fibrosis]. 890 44

Dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) in humans is frequently associated with progressive liver disease, which appears to result from obstruction of biliary ducts with mucous material. CFTR in the liver is expressed in the biliary epithelium. With the use of a mouse model for cystic fibrosis (CF) we have studied the relationship between CFTR expression and glycoprotein secretion in primary culture of mouse gallbladder epithelial cells (MGBC) MGBC in culture maintain a well-differentiated phenotype as shown by microscopy. The cells produce CFTR mRNA to levels comparable to the intact tissue. With patch-clamp analysis we could frequently observe a linear protein kinase A-regulated Cl- channel that shows all the major characteristics of human CFTR, although its conductance is lower (5 pS compared with 8 pS). MGBC in culture produce and secrete high molecular weight glycoproteins (HMG) in a time-dependent and temperature-sensitive manner. Secretion of HMG was not stimulated significantly by either adenosine 3',5'-cyclic monophosphate (cAMP), Ca2+, or protein kinase C agonists in this system. High concentrations (3 mM) of extracellular ATP stimulated secretion threefold, but low concentrations (0.3 mM) had no effect. Approximately one-third of the HMG produced and secreted consisted of mucin. Cultured MGBC from CFTR-deficient mice produced and secreted mucin to a similar extent as normal cells. We conclude that cultured mouse gallbladder cells are a convenient model to study both CFTR function and mucin secretion. In this system, we found no evidence for a direct link between mucin secretion and CFTR activity, as has been suggested for other cell types.
...
PMID:CFTR expression and mucin secretion in cultured mouse gallbladder epithelial cells. 899 52

The cystic fibrosis transmembrane conductance regulator (CFTR) is a transmembrane protein that is expressed in several epithelia, including kidney tubules. Mutations in CFTR (a PKA-chloride channel and/or regulator of other epithelial channels) give rise to the clinical manifestation of cystic fibrosis, and result in the synthesis of mutated proteins responsible for altering ion transport across secretory epithelia. The low abundance of endogenous CFTR makes a difficult to purify enough of the native protein to prepare anti-CFTR antibodies. We have used differential centrifugation to prepare cortical brush border membrane vesicles from pig kidney, cBBMV, and developed a method for the partial purification of CFTR. This is the first step in the isolation of native CFTR. The results show that CFTR is present in cBBMV. The purified protein will provide a clearer picture of the biophysical and biochemical properties of native CFTR.
...
PMID:Partial purification of the pig kidney cystic fibrosis transmembrane regulator protein. 903 46

The gene product affected in cystic fibrosis, the cystic fibrosis transmembrane conductance regulator (CFTR), is a chlorideselective ion channel that is regulated by cAMP-dependent protein kinase-mediated phosphorylation, ATP binding and ATP hydrolysis. Mutations in the CFTR gene may result in cystic fibrosis characterized by severe pathology (e.g. recurrent pulmonary infection, male infertility and pancreatic insufficiency) involving organs expressing the CFTR. Interestingly, in the kidney, where expression of the CFTR has been reported, impaired ion transport in patients suffering from cystic fibrosis could not be observed. To understand the role of the CFTR in chloride transport in the kidney, we attempted to identify an epithelial cell line that can serve as a model. We demonstrate that the CFTR is expressed constitutively in Madine-Darby canine kidney (MDCK) type I cells, which are thought to have originated from the distal tubule of the dog nephron. We show expression at the mRNA level, using reverse transcriptase-PCR, and at the protein level, using Western blot analysis with three different monoclonal antibodies. Iodide efflux measurements indicate that CFTR expression confers a plasma membrane anion conductance that is responsive to stimulation by cAMP. The cAMP-stimulated iodide release is sensitive to glybenclamide, diphenylamine carboxylic acid and 5-nitro-2-(3-phenylpropylamino)benzoic acid, but not to 4,4'-di-isothiocyanostilbene-2,2'-disulphonic acid, an inhibitor profile characteristic of the CFTR chloride channel. Finally, the polarized localization of the CFTR to the apical plasma membrane was established by iodide efflux measurements and cell-surface biotinylation on MDCK I monolayers. Interestingly, MDCK type II cells, which are thought to have originated from the proximal tubule of the kidney, lack CFTR protein expression and cAMP-stimulated chloride conductance. In conclusion, we propose that MDCK type I and II cells can serve as convenient model systems to study the physiological role and differential expression of CFTR in the distal and proximal tubule respectively.
...
PMID:Functional expression and apical localization of the cystic fibrosis transmembrane conductance regulator in MDCK I cells. 907 71

C-type natriuretic peptide (CNP), a hormone which stimulates particulate guanylate cyclase activity, was studied for its ability to stimulate chloride permeability through the cystic fibrosis transmembrane conductance regulator (CFTR) in airway epithelial cells. Two cell lines, Calu-3 and CF-T43, were used as models of normal and cystic fibrosis (CF) airway epithelial cells, respectively. Calu-3 cells, derived from a lung carcinoma, express relatively high levels of wild-type CFTR. CF-T43 is a transformed line derived from a nasal polyp and expresses the mutant CFTR, deltaF508. Calu-3 cells exposed to the nucleotide guanosine-3',5'-monophosphate (cGMP) analogue 8-Br-cGMP exhibit increased 36Cl- efflux, demonstrating that cGMP can mediate changes in chloride permeability. CNP induces a bumetanide-sensitive short circuit current across Calu-3 monolayers. Whole-cell currents stimulated by CNP display linear current-voltage relationships and have inhibitor pharmacology and ion selectivity consistent with CFTR channel activity. Sodium nitroprusside (SNP), an activator of soluble guanylate cyclase, and CNP both increase cGMP levels and short circuit current in Calu-3 cells. In contrast, exposure of CF-T43 cells to CNP resulted in an increased 36Cl- efflux rate only when combined with the adenylate cyclase agonist isoproterenol and the response was sensitive to kinase inhibitors. CF-T43 cells exposed to isoproterenol and SNP showed no increase in chloride efflux. Together, these data indicate that CNP can activate wild-type and mutant CFTR through a cAMP-dependent protein kinase pathway and that the sensitivity of Calu-3 cells for this stimulation is greater than that of the CF-T43 cells.
...
PMID:C-type natriuretic peptide increases chloride permeability in normal and cystic fibrosis airway cells. 911 58

Cystic fibrosis (CF) airway epithelia exhibit enhanced Na+ reabsorption in parallel with diminished Cl- secretion. We tested the hypothesis that actin plays a role in the regulation of a cloned epithelial Na+ channel (ENaC) by the cystic fibrosis transmembrane conductance regulator (CFTR). We found that immunopurified bovine tracheal CFTR coreconstituted into a planar lipid bilayer with alpha,beta,gamma-rat ENaC (rENaC) decreased single-channel open probability (Po) of rENaC in the presence of actin by over 60%, a significantly greater effect than was observed in the absence of actin (approximately 20%). In the presence of actin, protein kinase A plus ATP activated both CFTR and rENaC, but CFTR was activated in a sustained manner, whereas the activation of rENaC was transitory. ATP alone could also activate ENaC transiently in the presence ofactin but had no effect on CFTR. Stabilizing short actin filaments at a fixed length with gelsolin (at a ratio to actin of 2:1) produced a sustained activation of alpha,beta,gamma-rENaC in both the presence or absence of CFTR. Gelsolin alone (i.e., in the absence of actin) had no effect on the conductance or Po of either CFTR or rENaC. We have also found that short actin filaments produced their modulatory action on alpha-rENaC independent of the presence of the beta- or gamma-rENaC subunits. In contrast, CFTR did not affect any properties of the channel formed by alpha-rENaC alone, i.e., in the absence of beta- or gamma-rENaC. These results indicate that CFTR can directly downregulate single Na+ channel activity, which may account for the observed differences between Na+ transport in normal and CF-affected airway epithelia. Moreover, the presence of actin confers an enhanced modulatory ability of CFTR on Na+ channels.
...
PMID:Role of actin in regulation of epithelial sodium channels by CFTR. 914 32


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---