1,25-Dihydroxyvitamin D3 but not TPA activates PLD in Caco-2 cells via pp60c-src and RhoA

1999 ◽  
Vol 276 (4) ◽  
pp. G1005-G1015 ◽  
Author(s):  
Sharad Khare ◽  
Marc Bissonnette ◽  
Ramesh Wali ◽  
Susan Skarosi ◽  
Gerry R. Boss ◽  
...  
Keyword(s):  
Signal Transduction ◽  
G Proteins ◽  
Specific Inhibitor ◽  
Brefeldin A ◽  
Heterotrimeric G Proteins ◽  
Dihydroxyvitamin D3 ◽  
Dihydroxyvitamin D ◽  
Rho Family ◽  
Adp Ribosylation Factor ◽  
Stimulation Of

In the accompanying paper [Khare et al., Am. J. Physiol. 276 ( Gastrointest. Liver Physiol. 39): G993–G1004, 1999], activation of protein kinase C-α (PKC-α) was shown to be involved in the stimulation of phospholipase D (PLD) by 1,25-dihydroxyvitamin D3[1,25(OH)2D3] and 12- O-tetradecanoylphorbol 13-acetate (TPA) in Caco-2 cells. Monomeric or heterotrimeric G proteins, as well as pp60c- src have been implicated in PLD activation. We therefore determined whether these signal transduction elements were involved in PLD stimulation by 1,25(OH)2D3or TPA. Treatment with C3 transferase, which inhibits members of the Rho family of monomeric G proteins, markedly diminished the ability of 1,25(OH)2D3, but not TPA, to stimulate PLD. Brefeldin A, an inhibitor of ADP-ribosylation factor proteins, did not, however, significantly reduce the stimulation of PLD by either of these agents. Moreover, 1,25(OH)2D3, but not TPA, activated pp60c- src and treatment with PP1, a specific inhibitor of the pp60c- src family, blocked the ability of 1,25(OH)2D3to activate PLD. Pretreatment of cells with pertussis toxin (PTx) markedly reduced the stimulation of PLD by either agonist. PTx, moreover, inhibited the stimulation of pp60c- src and PKC-α by 1,25(OH)2D3. PTx did not, however, block the membrane translocation of RhoA induced by 1,25(OH)2D3or inhibit the stimulation of PKC-α by TPA. These findings, taken together with those of the accompanying paper, indicate that although 1,25(OH)2D3and TPA each activate PLD in Caco-2 cells in part via PKC-α, their stimulation of PLD differs in a number of important aspects, including the requirement for pp60c- src and RhoA in the activation of PLD by 1,25(OH)2D3, but not TPA. Moreover, the requirement for different signal transduction elements by 1,25(OH)2D3and TPA to induce the stimulation of PLD may potentially underlie differences in the physiological effects of these agents in Caco-2 cells.

scholarly journals Every Detail Matters. That Is, How the Interaction between Gα Proteins and Membrane Affects Their Function

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 222
Author(s):  
Agnieszka Polit ◽  
Paweł Mystek ◽  
Ewa Błasiak
Keyword(s):  
Signal Transduction ◽  
G Protein ◽  
G Proteins ◽  
Lipid Membranes ◽  
Signaling Proteins ◽  
Heterotrimeric G Proteins ◽  
Membrane Attachment ◽  
The Individual ◽  
Multicellular Organisms ◽  
G Protein Coupled

In highly organized multicellular organisms such as humans, the functions of an individual cell are dependent on signal transduction through G protein-coupled receptors (GPCRs) and subsequently heterotrimeric G proteins. As most of the elements belonging to the signal transduction system are bound to lipid membranes, researchers are showing increasing interest in studying the accompanying protein–lipid interactions, which have been demonstrated to not only provide the environment but also regulate proper and efficient signal transduction. The mode of interaction between the cell membrane and G proteins is well known. Despite this, the recognition mechanisms at the molecular level and how the individual G protein-membrane attachment signals are interrelated in the process of the complex control of membrane targeting of G proteins remain unelucidated. This review focuses on the mechanisms by which mammalian Gα subunits of G proteins interact with lipids and the factors responsible for the specificity of membrane association. We summarize recent data on how these signaling proteins are precisely targeted to a specific site in the membrane region by introducing well-defined modifications as well as through the presence of polybasic regions within these proteins and interactions with other components of the heterocomplex.

Modification of cardiac β-adrenoceptor mechanisms by H2O2

1998 ◽  
Vol 274 (2) ◽  
pp. H416-H423 ◽  
Author(s):  
Sujata Persad ◽  
Heinz Rupp ◽  
Rashi Jindal ◽  
Jugpal Arneja ◽  
Naranjan S. Dhalla
Keyword(s):  
Oxidative Stress ◽  
Signal Transduction ◽  
Adenylyl Cyclase ◽  
G Proteins ◽  
Cardiac Dysfunction ◽  
Biochemical Parameters ◽  
Adenylyl Cyclase Activity ◽  
High Concentrations ◽  
Stimulation Of

From the role of oxidative stress in cardiac dysfunction, we investigated the effect of H2O2, an activated species of oxygen, on β-adrenoceptors, G proteins, and adenylyl cyclase activities. Rat heart membranes were incubated with different concentrations of H2O2before the biochemical parameters were measured. Both the affinity and density of β1-adrenoceptors were decreased, whereas the density of the β2-adrenoceptors was decreased and the affinity was increased by 1 mM H2O2. Time- and concentration-dependent biphasic changes in adenylyl cyclase activities in the absence or presence of isoproterenol were observed when membranes were incubated with H2O2; however, activation of the enzyme by isoproterenol was increased or unaltered. The adenylyl cyclase activities in the absence or presence of forskolin, NaF, and Gpp(NH)p were depressed by H2O2. Catalase alone or in combination with mannitol was able to significantly decrease the magnitude of alterations due to H2O2. The cholera toxin-stimulated adenylyl cyclase activity and ADP ribose labeling of Gs proteins were decreased by treatment with 1 mM H2O2, whereas Gi protein activities, as reflected by pertussis toxin-stimulation of adenylyl cyclase and ADP ribosylation, were unaltered. The Gs and Gi protein immunoreactivities, estimated by labeling with respective antibodies, indicate a decrease in binding to the 45-kDa band of Gs protein, whereas no change in the binding of antibodies to the 52-kDa band of Gs protein or the 40-kDa subunit of Gi protein was evident when the membranes were treated with 1 mM H2O2. These results suggest that H2O2in high concentrations may attenuate the β-adrenoceptor-linked signal transduction in the heart by changing the functions of Gs proteins and the catalytic subunit of the adenylyl cyclase enzyme.

scholarly journals Plant hormone perception and action: a role for G–protein signal transduction?

1998 ◽  
Vol 353 (1374) ◽  
pp. 1425-1430 ◽  
Author(s):  
Richard Hooley
Keyword(s):  
Signal Transduction ◽  
G Protein ◽  
G Proteins ◽  
Plant Hormone ◽  
Higher Plants ◽  
Signalling Pathways ◽  
Heterotrimeric G Proteins ◽  
Extracellular Signals ◽  
G Protein Signalling ◽  
Auxin Signalling

Plants perceive and respond to a profusion of environmental and endogenous signals that influence their growth and development. The G–protein signalling pathway is a mechanism for transducing extracellular signals that is highly conserved in a range of eukaryotes and prokaryotes. Evidence for the existence of G–protein signalling pathways in higher plants is reviewed, and their potential involvement in plant hormone signal transduction evaluated. A range of biochemical and molecular studies have identified potential components of G–protein signalling in plants, most notably a homologue of the G–protein coupled receptor superfamily ( GCR1 ) and the G α and G β subunits of heterotrimeric G–proteins. G–protein agonists and antagonists are known to influence a variety of signalling events in plants and have been used to implicate heterotrimeric G–proteins in gibberellin and possibly auxin signalling. Antisense suppression of GCR1 in Arabidopsis leads to a phenotype which supports a role for this receptor in cytokinin signalling. These observations suggest that higher plants have at least some of the components of G–protein signalling pathways and that these might be involved in the action of certain plant hormones.

scholarly journals Interaction of Ras with phosphoinositide 3-kinase γ

1997 ◽  
Vol 326 (3) ◽  
pp. 891-895 ◽  
Author(s):  
Ignacio RUBIO ◽  
Pablo RODRIGUEZ-VICIANA ◽  
Julian DOWNWARD ◽  
Reinhard WETZKER
Keyword(s):  
Binding Site ◽  
G Proteins ◽  
Terminal Region ◽  
Regulatory Subunit ◽  
Heterotrimeric G Proteins ◽  
Modest Increase ◽  
Pi3k Activity ◽  
Phosphoinositide 3 Kinase ◽  
Stimulation Of

Phosphoinositide 3-kinase γ (PI3Kγ) can be activated in vitro by both α and βγ subunits of heterotrimeric G-proteins and does not interact with p85, the regulatory subunit of PI3Kα. Here we demonstrate the binding of Ras to PI3Kγ in vitro. An N-terminal region of PI3Kγ was identified as a binding site for Ras. After co-expression with PI3Kγ in COS-7 cells, Ras induced only a modest increase in PI3K activity compared with the stimulation of PI3Kα by Ras in the same cells.

scholarly journals RGS7 Attenuates Signal Transduction Through the Gαq Family of Heterotrimeric G Proteins in Mammalian Cells

2002 ◽  
Vol 70 (5) ◽  
pp. 1964-1972 ◽  
Author(s):  
David J. Shuey ◽  
Maria Betty ◽  
Philip G. Jones ◽  
Xavier Z. Khawaja ◽  
Mark I. Cockett
Keyword(s):  
Signal Transduction ◽  
G Proteins ◽  
Mammalian Cells ◽  
Heterotrimeric G Proteins

Insulin modulates the stimulation of renal 1,25-dihydroxyvitamin D3 production by parathyroid hormone

1985 ◽  
Vol 109 (2) ◽  
pp. 243-248 ◽  
Author(s):  
Nirandon Wongsurawat ◽  
H. James Armbrecht
Keyword(s):  
Vitamin D ◽  
Parathyroid Hormone ◽  
Diabetic Rats ◽  
Biologically Active ◽  
Renal Handling ◽  
Dihydroxyvitamin D3 ◽  
Dihydroxyvitamin D ◽  
Maximal Stimulation ◽  
Insulin Replacement ◽  
Stimulation Of

Abstract. Previous studies have shown that there is an impairment in renal production of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), the major biologically active metabolite of vitamin D3, in diabetes. This impairment is not due to a deficiency in the parathyroid hormone (PTH), a major stimulator of renal 1,25(OH)2D3 production. Therefore, we have investigated the capacity of PTH to stimulate 1,25(OH)2D3 production in insulin deficiency and with insulin replacement. Experiments were performed in rats fed a 0.6% calcium, vitamin D sufficient diet for 2 weeks. Thyroparathyroidectomy was performed on all rats. Rats to be rendered diabetic were injected with streptozotocin immediately after surgery. In non-diabetic rats, PTH administration significantly increased renal 1,25(OH)2D3 production (11 ± 2 vs 46 ± 5 pg/min/g; P < 0.05). In diabetic rats, however, PTH caused only a modest increase in 1,25(OH)2D3 production (11 ± 1 vs 19 ± 4 pg/min/g; P < 0.05). With insulin replacement, PTH stimulation of 1,25(OH)2D3 production was markedly increased over that seen in diabetic rats (48 ± 12 vs 19 ± 4 pg/min/g; P < 0.05). PTH was equally effective in raising serum calcium, depressing serum phosphorus and tubular reabsorption of phosphate in non-diabetic as well as in diabetic rats. These results demonstrate that insulin is necessary for the maximal stimulation of renal 1,25(OH)2D3 production by PTH. However, insulin is not necessary for PTH action in terms of renal handling of phosphate and inducing hypercalcaemia. These results suggest multiple pathways for the action of PTH, only some of which are insulin requiring.

scholarly journals Signal Transduction of Heterotrimeric G Proteins in Lipid Rafts

2007 ◽  
Vol 19 (105) ◽  
pp. 19-27 ◽  
Author(s):  
Kohei Yuyama ◽  
Naoko Sekino-Suzuki ◽  
Kohji Kasahara
Keyword(s):  
Signal Transduction ◽  
Lipid Rafts ◽  
G Proteins ◽  
Heterotrimeric G Proteins

1,25-Dihydroxyvitamin D3 and TPA activate phospholipase D in Caco-2 cells: role of PKC-α

1999 ◽  
Vol 276 (4) ◽  
pp. G993-G1004 ◽  
Author(s):  
Sharad Khare ◽  
Marc Bissonnette ◽  
Beth Scaglione-Sewell ◽  
Ramesh K. Wali ◽  
Michael D. Sitrin ◽  
...  
Keyword(s):  
Phospholipase D ◽  
Dihydroxyvitamin D3 ◽  
Dihydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Gf 109203X ◽  
Pkc Β ◽  
Stimulation Of

1,25-Dihydroxyvitamin D3[1,25(OH)2D3] and 12- O-tetradecanoylphorbol 13-acetate (TPA) both activated phospholipase D (PLD) in Caco-2 cells. GF-109203x, an inhibitor of protein kinase C (PKC) isoforms, inhibited this activation by both of these agonists. 1,25(OH)2D3activated PKC-α, but not PKC-β1, -βII, -δ, or -ζ, whereas TPA activated PKC-α, -β1, and -δ. Chronic treatment with TPA (1 μM, 24 h) significantly reduced the expression of PKC-α, -βI, and -δ and markedly reduced the ability of 1,25(OH)2D3or TPA to acutely stimulate PLD. Removal of Ca2+ from the medium, as well as preincubation of cells with Gö-6976, an inhibitor of Ca2+-dependent PKC isoforms, significantly reduced the stimulation of PLD by 1,25(OH)2D3or TPA. Treatment with 12-deoxyphorbol-13-phenylacetate-20-acetate, which specifically activates PKC-βI and -βII, however, failed to stimulate PLD. In addition, the activation of PLD by 1,25(OH)2D3or TPA was markedly reduced or accentuated in stably transfected cells with inhibited or amplified PKC-α expression, respectively. Taken together, these observations indicate that PKC-α is intimately involved in the stimulation of PLD in Caco-2 cells by 1,25(OH)2D3or TPA.

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