Relationship of GTP-binding proteins, phospholipase C, and PGE2 synthesis in rat glomerular mesangial cells

1989 ◽  
Vol 256 (1) ◽  
pp. F171-F178 ◽  
Author(s):  
D. Schlondorff ◽  
P. Singhal ◽  
A. Hassid ◽  
J. A. Satriano ◽  
S. DeCandido
Keyword(s):  
Arachidonic Acid ◽  
Phospholipase C ◽  
G Protein ◽  
Binding Proteins ◽  
Mesangial Cells ◽  
Cdna Probe ◽  
Ang Ii ◽  
Glomerular Mesangial Cells ◽  
Gtp Binding Proteins ◽  
Gtp Binding

We evaluated the role of GTP-binding proteins in the activation of phospholipase C, release of arachidonic acid, and synthesis of prostaglandin (PG) E2 in response to platelet-activating factor (PAF) and angiotensin II (ANG II) in cultured rat mesangial cells. Pretreatment with pertussis toxin (PT) decreased PGE2 formation and arachidonic acid release in response to PAF and ANG II but not that to A 23187. PT pretreatment also inhibited formation of inositol trisphosphate (IP3) in response to ANG II or PAF but did not significantly alter the rise in intracellular calcium detected by fura-2. PT catalyzed ADP ribosylation of two proteins of molecular mass approximately 40 and 41 kDa. Further evidence for involvement of GTP-binding protein in phospholipase C activation was that GTP-gamma S stimulated IP3 generation. Immunoblots with antibodies directed against different inhibitory alpha subunits of GTP-binding proteins showed that the major 40-kDa PT substrate reacted with an antibody directed against a decapeptide of the G protein subunit alpha i2 that is also found in leukocytes. This was further confirmed by Northern blot that showed the existence of mRNA in mesangial cells that hybridized with a cDNA probe for G alpha i2. In addition lesser amounts of mRNA hybridized with a restriction fragment cDNA probe for G alpha i3, which corresponds to the 41-kDa substrate for PT ribosylation. These results show that phospholipase C activation by PAF and ANG II in mesangial cells involves a specific G protein, most likely G alpha i2.(ABSTRACT TRUNCATED AT 250 WORDS)

A pertussis toxin-sensitive GTP-binding protein couples endothelin to phospholipase C in rat mesangial cells

1991 ◽  
Vol 260 (3) ◽  
pp. F347-F352
Author(s):  
C. P. Thomas ◽  
M. Kester ◽  
M. J. Dunn
Keyword(s):  
Phospholipase C ◽  
Pertussis Toxin ◽  
Binding Proteins ◽  
Mesangial Cells ◽  
Binding Protein ◽  
Glomerular Mesangial Cells ◽  
Gtp Binding Protein ◽  
Intact Cells ◽  
Gtp Binding ◽  
Stimulation Of

The mechanisms of stimulation of phospholipase C (PLC) by endothelin, specifically the role of guanine nucleotide-binding proteins (GTP-binding proteins) in coupling the endothelin receptor to PLC, were investigated in rat mesangial cells. Endothelin-1 (ET) synergistically released inositol polyphosphates in the presence of the stimulatory GTP analogue guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) in permeabilized cells. In addition, in intact cells, pertussis toxin partially inhibited the stimulation of total inositol phosphates (IPn) by ET. Pertussis toxin also reduced the peak ET-stimulated intracellular free calcium level ([Ca2+]i) in these cells, both in the presence and absence of extracellular calcium. Pertussis toxin induced ADP ribosylation of a 41- to 43-kDa protein in mesangial cell membranes, and this effect was inhibited by prior exposure to ET and augmented by the inhibitory GDP analogue, guanosine 5'-O-(2-thiodiphosphate) (GDP beta S). Thus a pertussis toxin-sensitive GTP-binding protein is involved in the activation of PLC by ET in glomerular mesangial cells.

scholarly journals Regulation of glucose carrier activity by AlCl3 and phospholipase C in fat-cells

1988 ◽  
Vol 256 (2) ◽  
pp. 515-520 ◽  
Author(s):  
B Obermaier-Kusser ◽  
C Mühlbacher ◽  
J Mushack ◽  
E Rattenhuber ◽  
M Fehlmann ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Phospholipase C ◽  
G Protein ◽  
Glucose Transport ◽  
Pertussis Toxin ◽  
Binding Proteins ◽  
Fat Cells ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Glucose Carrier

Recently it was speculated that activation of GTP-binding proteins and of phospholipase is involved in the transmission of a signal from the insulin-receptor kinase to effector systems in the cell. To confirm this hypothesis, we have tested the effect of AlCl3, which has been recently used as an experimental tool to activate GTP-binding proteins, on glucose transport in fat-cells. We found that AlCl3 has a partial insulin-like effect on glucose transport activity (3-O-methylglucose uptake, expressed as % of equilibrium value per 4 s: basal 9.6 +/- 2, AlCl3 29.6 +/- 4, insulin 74.0 +/- 3). The AlCl3 effect is totally blocked by pertussis toxin, whereas the insulin effect was not altered. The effect starts at [AlCl3] greater than 1 fM and reaches its maximum at 0.1 nM. Addition of phospholipase C (PLC; 50 munits/ml) also stimulated glucose transport (maximal 53.0 +/- 5%). Both substances acted faster than insulin itself (maximal values within 1 min for PLC, 2 min for AlCl3 and 5-10 min for insulin). Using the cytochalasin-B-binding assay to determine the effects of AlCl3 and PLC on the distribution of glucose carrier sites in subcellular fractions, we found that their glucose-transport-stimulating effect does not occur through an increase in glucose carrier sites in the plasma-membrane fraction. When PLC was combined with the phorbol ester TPA (12-O-tetradecanoylphorbol 13-acetate), which increases glucose carrier sites in the plasma membrane, an additive effect on glucose transport was found [PLC (50 munits/ml), 53.0 +/- 5%, TPA (1 nM), 17.3 +/- 2%; PLC + TPA, 68.0 +/- 3%]. In conclusion: (1) the data show that AlCl3, probably through activation of a pertussis-toxin-inhibitable G protein, and PLC are able to modulate the intrinsic glucose carrier activity; (2) as pertussis toxin did not modify the effect of insulin, it seems unlikely that the insulin signal on glucose transport involves activation of this specific G protein.

Endothelin Receptors and Coupled GTP-Binding Proteins in Glomerular Mesangial Cells

1991 ◽  
Vol 17 ◽  
pp. S79 ◽  
Author(s):  
Christie P. Thomas ◽  
Elisabetta Baldi ◽  
Michael S. Simonson ◽  
Mark Kester ◽  
Michael J. Dunn
Keyword(s):  
Binding Proteins ◽  
Mesangial Cells ◽  
Endothelin Receptors ◽  
Glomerular Mesangial Cells ◽  
Gtp Binding Proteins ◽  
Gtp Binding

Interaction of G protein Gβγ dimers with small GTP-binding proteins of the Rho family

FEBS Letters ◽  
1996 ◽  
Vol 399 (3) ◽  
pp. 211-214 ◽  
Author(s):  
Rainer Harhammer ◽  
Antje Gohla ◽  
Günter Schultz
Keyword(s):  
G Protein ◽  
Binding Proteins ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Rho Family

A role for G-proteins in the epidermal growth factor stimulation of phospholipase A2 in rat kidney mesangial cells

1990 ◽  
Vol 10 (4) ◽  
pp. 353-362 ◽  
Author(s):  
Nashrudeen Hack ◽  
Paula Clayman ◽  
Karl Skorecki
Keyword(s):  
Arachidonic Acid ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Phospholipase A2 ◽  
G Protein ◽  
Mesangial Cells ◽  
Rat Kidney ◽  
Glomerular Mesangial Cells ◽  
Epidermal Growth ◽  
Stimulation Of

We have previously demonstrated phospholipase C (PLC) independent activation of phospholipase A2(PLA2) by epidermal growth factor (EGF) in glomerular mesangial cells in culture. In the current study using glass beads to permeabilize [3H]- or [14C]-arachidonate labelled mesangial cells we demonstrate that guanine nucleotides modulate the EGF-mediated stimulation of arachidonic acid release (75% inhibition with 100 μM GDPβS and 108% augmentation with 100 μM GTPγS). GTPγS alone stimulated both the release of free arachidonic acid and production of diacylglycerol (DAG), while EGF itself neither stimulated DAG nor augmented the DAG response to GTPγS. These findings suggest the intermediacy of a G-protein in PLC-independent stimulation of PLA2 by a growth factor, and provide a model system for determining the relationship between G-protein intermediacy and the intrinsic tyrosine kinase activity of the growth factor receptor.

Stimulation by GTP-binding proteins (Gi, Go) of partially purified phospholipase C activity from human platelet membranes

1987 ◽  
Vol 146 (2) ◽  
pp. 861-869 ◽  
Author(s):  
Yoshiko Banno ◽  
Seiji Nagao ◽  
Toshiaki Katada ◽  
Koh-ichi Nagata ◽  
Michio Ui ◽  
...  
Keyword(s):  
Phospholipase C ◽  
Binding Proteins ◽  
Human Platelet ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Platelet Membranes

ANG II-induced tyrosine phosphorylation stimulates phospholipase C-gamma 1 and Cl-channels in mesangial cells

1996 ◽  
Vol 270 (6) ◽  
pp. C1834-C1842 ◽  
Author(s):  
M. B. Marrero ◽  
B. Schieffer ◽  
H. Ma ◽  
K. E. Bernstein ◽  
B. N. Ling
Keyword(s):  
Signal Transduction ◽  
Phospholipase C ◽  
Tyrosine Phosphorylation ◽  
Mesangial Cells ◽  
Inositol Phosphate ◽  
Signal Transduction Pathway ◽  
Ang Ii ◽  
Glomerular Mesangial Cells ◽  
Open Probability ◽  
Cl Channels

Angiotensin II (ANG II)-induced, activation of phospholipase C (PLC) and Ca(2+)-dependent Cl-channels is an important signal transduction pathway for mesangial cell contraction and growth. Although ANG II receptors are traditionally though to be G protein coupled, recent evidence suggests that they may also mediate protein tyrosine phosphorylation. In cultured rat mesangial cells, 10(-7) MANG II stimulated the tyrosine phosphorylation of PLC-gamma 1 and elevation of intracellular inositol 1,4,5-trisphosphate (IP3) and Ca2+ levels; peak response occurred within 0.5 min. In cell-attached patches, ANG II stimulated the activity of Ca(2+)-dependent, 3- to 4-pS Cl-channels (number of channels x open probability) from 0.063 +/- 0.022 to 0.77 +/- 0.20. Tyrosine kinase inhibition with genistein or herbimycin A blocked all four ANG II-induced responses. We conclude the following. 1) Stimulation of inositol phosphate hydrolysis by PLC, release of IP3-dependent intracellular Ca2+ stores, and activation of Ca(2+)-dependent C1-channels by ANG II are dependent on the tyrosine phosphorylation of PLC-gamma 1.2) This ANG II-induced signal transduction cascade provides a possible mechanism for both the contractile and growth-stimulating effects of ANG II on glomerular mesangial cells.

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