Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A heterotrimeric G alpha i subunit, alpha i-3, is localized on Golgi membranes in LLC-PK1 and NRK epithelial cells where it colocalizes with mannosidase II by immunofluorescence. The alpha i-3 was found to be localized on the cytoplasmic face of Golgi cisternae and it was distributed across the whole Golgi stack. The alpha i-3 subunit is found on isolated rat liver Golgi membranes by Western blotting and G alpha i-3 on the Golgi apparatus is ADP ribosylated by pertussis toxin. LLC-PK1 cells were stably transfected with G alpha i-3 on an MT-1, inducible promoter in order to overexpress alpha i-3 on Golgi membranes. The intracellular processing and constitutive secretion of the basement membrane heparan sulfate proteoglycan (HSPG) was measured in LLC-PK1 cells. Overexpression of alpha i-3 on Golgi membranes in transfected cells retarded the secretion of HSPG and accumulated precursors in the medial-trans-Golgi. This effect was reversed by treatment of cells with pertussis toxin which results in ADP-ribosylation and functional uncoupling of G alpha i-3 on Golgi membranes. These results provide evidence for a novel role for the pertussis toxin sensitive G alpha i-3 protein in Golgi trafficking of a constitutively secreted protein in epithelial cells.
 ...
PMID:A heterotrimeric G protein, G alpha i-3, on Golgi membranes regulates the secretion of a heparan sulfate proteoglycan in LLC-PK1 epithelial cells. 191 49

The formation of vesicles for protein trafficking requires the dynamic binding of cytosolic coat proteins onto Golgi membranes and this binding is regulated by a variety of GTPases, including heterotrimeric G proteins. We have previously shown the presence of the pertussis toxin-sensitive G alpha i-3 protein on Golgi membranes and demonstrated a functional role for G alpha i-3 in the trafficking of secretory proteins through the Golgi complex. We have also described a brefeldin A-sensitive phosphoprotein, p200, which is found in the cytoplasm and on Golgi membranes. The present study investigates the role of heterotrimeric G proteins in the regulation of p200 binding to Golgi membranes. An in vitro binding assay was used to measure the binding of cytosolic p200 to LLC-PK1 cell microsomal membranes and to purified rat liver Golgi membranes in the presence of specific activators of G proteins. The binding of p200 to Golgi membranes was compared to that of the coatomer protein beta-COP, for which G protein-dependent membrane binding has previously been established. Membrane binding of both p200 and beta-COP was induced maximally by activation of all G proteins in the presence of GTP gamma S. More selective activation of the heterotrimeric G proteins, with AlFn or mastoparan, also induced membrane binding of p200 and beta-COP. Pertussis toxin pretreatment of Golgi membranes, to selectively inactivate G alpha i-3, reduced the AlFn and mastoparan-induced binding of p200 to Golgi membranes, whereas no significant effect of pertussis toxin on beta-COP binding was found in this assay. The effect of pertussis toxin thus implicates G alpha i-3, as one component of a regulatory pathway, in the binding of cytosolic p200 to Golgi membranes. The effects of AlFn and pertussis toxin on p200 membrane binding were also shown in intact cells by immunofluorescence staining. AlFn treatment of cells induced translocation of p200 from the cytoplasm onto the Golgi complex, resulting in a conformational change in some Golgi membranes. The translocation of p200 was blocked by pretreatment of intact NRK cells with pertussis toxin. The data presented here support the conclusion that the binding of the p200 protein to Golgi membranes involves regulation by the pertussis toxin-sensitive heterotrimeric G proteins, specifically the G alpha i-3 protein.
 ...
PMID:Binding of the cytosolic p200 protein to Golgi membranes is regulated by heterotrimeric G proteins. 812 4

Corticosteroid regulation of Na/K-ATPase is of key importance in the modulation of Na+ transport across renal tubular epithelia. In amphibian renal cells, aldosterone induction of Na/K-ATPase alpha 1 and beta 1 subunit gene transcription is mediated by an indirect mechanism dependent on the synthesis of a labile protein. In mammalian target cells, while both mineralo- and glucocorticoids increase the levels of Na/K-ATPase alpha 1 and beta 1 subunit mRNA and enzyme activity, they are diminished by glycyrrhetinic acid (GE), the active ingredient of licorice. To investigate the mechanisms underlying the regulation of mammalian renal Na/K-ATPase, levels of alpha 1 and beta 1 mRNA were measured in rat kidney epithelial (NRK-52E) cells treated with a range of concentrations of aldosterone, corticosterone and GE in the presence of a specific inhibitor of mRNA synthesis, dichlororibofuranosylbenzimidazole (DRB), an inhibitor of total RNA synthesis, actinomycin D (ActD), and the protein synthesis inhibitor cycloheximide (CHX). In addition, GE was co-incubated with the sodium channel antagonist benzamiloride (BZ). The increase in both alpha 1 and beta 1 mRNA levels following aldosterone and corticosterone was completely abolished by treatment with ActD and DRB, while CHX did not affect this response. Similarly, the GE-induced decrease in alpha 1 and beta 1 mRNA was also completely abolished by ActD and DRB, but not by CHX or by BZ. The half-lives of alpha 1 and beta 1 mRNA in these cells (means +/- S.E.M., n = 4), estimated from the rate of mRNA decay in the presence of DRB, were 6.8 +/- 0.3 and 4.8 +/- 0.2 h respectively. This was unaffected by GE. The inhibitory action of GE on alpha 1 and beta 1 mRNA levels was accompanied by a dose-dependent decrease in levels of intracellular cAMP (means +/- S.E.M., n = 4) from 395 +/- 28 fmol cAMP/microgram total cell protein to between 275 +/- 19 fmol/micrograms total cell protein (0.1 microM GE) and 78 +/- 11 fmol/micrograms total cell protein (10 microM GE). This was abolished following down-regulation of protein kinase C by prolonged treatment with the phorbol ester tetradecanoylphorbol-13-acetate (TPA), and by pertussis toxin (PT), but not by cholera toxin (CT). Indeed, subunit mRNA levels were increased by 8-bromo-cAMP (2.2-fold) and stimulators of adenylate cyclase activity, i.e. forskolin (2.1-fold), PT (2.1-fold) and CT (1.9-fold), but not by TPA.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Transcriptional regulation of Na/K-ATPase by corticosteroids, glycyrrhetinic acid and second messenger pathways in rat kidney epithelial cells. 854 17

The inhibition of adenylyl cyclase (AC) by a 12-lipoxygenase metabolite of arachidonic acid, 12(S)-hydroxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (12-HETE), was investigated using three different kinds of cells: NRK-49F (normal rat kidney fibroblasts), AtT-20 (mouse pituitary tumor cell line) and HL-60 (human leukemia cells) cells. The inhibition was very obvious in NRK-49F and AtT-20 cells, but it was almost negligible in HL-60 cells. There was no difference in terms of the binding of 12-HETE to NRK-49F and HL-60 cells. Pretreatment of NRK-49F cells with pertussis toxin almost completely ADP-ribosylated Gi proteins, but it did not affect the inhibition of 12-HETE on AC in this cell. This result excludes the involvement of Gi proteins in 12-HETE-mediated inhibition of AC. It was revealed that the characteristics of ACs in these cells were quite different in response to agonists and forskolin, suggesting that these cells do have different isoform of AC. We conclude that 12-HETE inhibits the activity of AC depending upon the isoform.
 ...
PMID:Inhibition of adenylyl cyclases by 12(S)-hydroxyeicosatetraenoic acid. 891 39