scholarly journals Defective coupling of apical PTH receptors to phospholipase C prevents internalization of the Na+-phosphate cotransporter NaPi-IIa in Nherf1-deficient mice

2007 ◽  
Vol 292 (2) ◽  
pp. C927-C934 ◽  
Author(s):  
Paola Capuano ◽  
Desa Bacic ◽  
Marcel Roos ◽  
Serge M. Gisler ◽  
Gerti Stange ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Proximal Tubule ◽  
Phospholipase C ◽  
Wild Type ◽  
Phosphate Reabsorption ◽  
Kinase C ◽  
Deficient Mice ◽  
Stimulation Of

Phosphate reabsorption in the renal proximal tubule occurs mostly via the type IIa Na+-phosphate cotransporter (NaPi-IIa) in the brush border membrane (BBM). The activity and localization of NaPi-IIa are regulated, among other factors, by parathyroid hormone (PTH). NaPi-IIa interacts in vitro via its last three COOH-terminal amino acids with the PDZ protein Na+/H+-exchanger isoform 3 regulatory factor (NHERF)-1 (NHERF1). Renal phosphate reabsorption in Nherf1-deficient mice is altered, and NaPi-IIa expression in the BBM is reduced. In addition, it has been proposed that NHERF1 and NHERF2 are important for the coupling of PTH receptors (PTHRs) to phospholipase C (PLC) and the activation of the protein kinase C pathway. We tested the role of NHERF1 in the regulation of NaPi-IIa by PTH in Nherf1-deficient mice. Immunohistochemistry and Western blotting demonstrated that stimulation of apical and basolateral receptors with PTH-(1–34) led to internalization of NaPi-IIa in wild-type and Nherf1-deficient mice. Stimulation of only apical receptors with PTH-(3–34) failed to induce internalization in Nherf1-deficient mice. Expression and localization of apical PTHRs were similar in wild-type and Nherf1-deficient mice. Activation of the protein kinase C- and A-dependent pathways with 1,2-dioctanoyl- sn-glycerol or 8-bromo-cAMP induced normal internalization of NaPi-IIa in wild-type, as well as Nherf1-deficient, mice. Stimulation of PLC activity due to apical PTHRs was impaired in Nherf1-deficient mice. These data suggest that NHERF1 in the proximal tubule is important for PTH-induced internalization of NaPi-IIa and, specifically, couples the apical PTHR to PLC.

scholarly journals G-protein βγ subunits antagonize protein kinase C-dependent phosphorylation and inhibition of phospholipase C-β1

1997 ◽  
Vol 326 (3) ◽  
pp. 701-707 ◽  
Author(s):  
Irene LITOSCH
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phospholipase C ◽  
G Protein ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Negative Feedback Regulation ◽  
Kinase C ◽  
Stimulation Of

Protein kinase C (PKC) isoforms phosphorylated phospholipase C-β1 (PLC-β1) in vitro as follows: PKCα ≫ PKCϵ; not PKCζ. PLC-β3 was not phosphorylated by PKCα. G-protein βγ subunits inhibited the PKCα phosphorylation of PLC-β1 in a concentration-dependent manner. Half-maximal inhibition occurred with 500 nM βγ. G-protein βγ subunits also antagonized the PKCα-mediated inhibition of PLC-β1 enzymic activity. PKCα, in turn, inhibited the stimulation of PLC-β1 activity by βγ. There was little effect of PKCα on the stimulation of PLC-β1 by αq/11–guanosine 5′[γ-thio]triphosphate (GTP[S]). These findings demonstrate that G protein βγ subunits antagonize PKCα regulation of PLC-β1. Thus βγ subunits might have a role in modulating the negative feedback regulation of this signalling system by PKC.

Stimulation of transient elevations in cytosolic Ca2+ is related to inhibition of Pi transport in OK cells

1990 ◽  
Vol 259 (3) ◽  
pp. F485-F493 ◽  
Author(s):  
A. Miyauchi ◽  
V. Dobre ◽  
M. Rickmeyer ◽  
J. Cole ◽  
L. Forte ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Parathyroid Hormone ◽  
Protein Kinase ◽  
Phospholipase C ◽  
Cytosolic Calcium ◽  
Wild Type ◽  
Kinase C ◽  
Pi Transport ◽  
Sodium Dependent ◽  
Stimulation Of

Stimulation of changes in cytosolic free calcium by parathyroid hormone was determined in three opossum kidney (OK) cell types, OK wild-type, OKP clone, and OKH clone. All three types of OK cells express parathyroid hormone (PTH)-sensitive adenylate cyclase and adenosine 3',5'-cyclic monophosphate (cAMP) production. However, only the OK wild-type and the OKP clone respond to PTH with inhibition of sodium-dependent Pi transport and transient increase in cytosolic calcium. Characterization of the increases in cytosolic calcium in the wild-type and OKP clones revealed they were due in part to stimulation of Ca2+ release from intracellular stores, probably by inositol 1,4,5-trisphosphate (IP3), which was stimulated by PTH. PTH-stimulated Ca2+ transients were also inhibited by protein kinase C activation. These data are compatible with PTH receptor-mediated phospholipase C activation and its feedback inhibition by protein kinase C. The OKH cells demonstrated a slow increase in cytosolic calcium when stimulated by cyclic nucleotides but no evidence for PTH stimulation of Ca2+ release from intracellular stores. Thus the absence of an inhibitory response of sodium-dependent Pi transport to PTH in the OKH cells is associated with the absence of the rapid transient elevations of cytosolic Ca2+ such as those produced by IP3 production. These data suggest an important cooperative role for cAMP and the phospholipase C-stimulated Ca2(+)-protein kinase C message system in the regulation of Pi transport.

Regulation of oxytocin secretion by the ovine corpus luteum: effect of activators of protein kinase C

1990 ◽  
Vol 124 (2) ◽  
pp. 225-232 ◽  
Author(s):  
J. J. Hirst ◽  
G. E. Rice ◽  
G. Jenkin ◽  
G. D. Thorburn
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Corpus Luteum ◽  
Phospholipase C ◽  
Tissue Slices ◽  
Kinase C ◽  
Luteal Tissue ◽  
Dose Dependent ◽  
Stimulation Of

ABSTRACT The effect of protein kinase C activation and dibutyryl cyclic AMP on oxytocin secretion by ovine luteal tissue slices was investigated. Several putative regulators of luteal oxytocin secretion were also examined. Oxytocin was secreted by luteal tissue slices at a basal rate of 234·4 ± 32·8 pmol/g per h (n = 24) during 60-min incubations.Activators of protein kinase C: phorbol 12,13-dibutyrate (n = 8), phorbol 12-myristate,13-acetate (n = 4) and 1,2-didecanoylglycerol (n = 5), caused a dose-dependent stimulation of oxytocin secretion in the presence of a calcium ionophore (A23187; 0·2 μmol/l). Phospholipase C (PLC; 50–250 units/l) also caused a dose-dependent stimulation of oxytocin secretion by luteal slices. Phospholipase C-stimulated oxytocin secretion was potentiated by the addition of an inhibitor of diacylglycerol kinase (R59 022; n = 4). These data suggest that the activation of protein kinase C has a role in the stimulation of luteal oxytocin secretion. The results are also consistent with the involvement of protein kinase C in PLC-stimulated oxytocin secretion. The cyclic AMP second messenger system does not appear to be involved in the control of oxytocin secretion by the corpus luteum. Journal of Endocrinology (1990) 124, 225–232

scholarly journals Targeting of Protein Kinase C-ϵ during Fcγ Receptor-dependent Phagocytosis Requires the ϵC1B Domain and Phospholipase C-γ1

2006 ◽  
Vol 17 (2) ◽  
pp. 799-813 ◽  
Author(s):  
Keylon L. Cheeseman ◽  
Takehiko Ueyama ◽  
Tanya M. Michaud ◽  
Kaori Kashiwagi ◽  
Demin Wang ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phospholipase C ◽  
Phospholipase D ◽  
Fluorescent Protein ◽  
Wild Type ◽  
Fcγ Receptor ◽  
Kinase C ◽  
Green Fluorescent

Protein kinase C-ϵ (PKC-ϵ) translocates to phagosomes and promotes uptake of IgG-opsonized targets. To identify the regions responsible for this concentration, green fluorescent protein (GFP)-protein kinase C-ϵ mutants were tracked during phagocytosis and in response to exogenous lipids. Deletion of the diacylglycerol (DAG)-binding ϵC1 and ϵC1B domains, or the ϵC1B point mutant ϵC259G, decreased accumulation at phagosomes and membrane translocation in response to exogenous DAG. Quantitation of GFP revealed that ϵC259G, ϵC1, and ϵC1B accumulation at phagosomes was significantly less than that of intact PKC-ϵ. Also, the DAG antagonist 1-hexadecyl-2-acetyl glycerol (EI-150) blocked PKC-ϵ translocation. Thus, DAG binding to ϵC1B is necessary for PKC-ϵ translocation. The role of phospholipase D (PLD), phosphatidylinositol-specific phospholipase C (PI-PLC)-γ1, and PI-PLC-γ2 in PKC-ϵ accumulation was assessed. Although GFP-PLD2 localized to phagosomes and enhanced phagocytosis, PLD inhibition did not alter target ingestion or PKC-ϵ localization. In contrast, the PI-PLC inhibitor U73122 decreased both phagocytosis and PKC-ϵ accumulation. Although expression of PI-PLC-γ2 is higher than that of PI-PLC-γ1, PI-PLC-γ1 but not PI-PLC-γ2 consistently concentrated at phagosomes. Macrophages from PI-PLC-γ2-/-mice were similar to wild-type macrophages in their rate and extent of phagocytosis, their accumulation of PKC-ϵ at the phagosome, and their sensitivity to U73122. This implicates PI-PLC-γ1 as the enzyme that supports PKC-ϵ localization and phagocytosis. That PI-PLC-γ1 was transiently tyrosine phosphorylated in nascent phagosomes is consistent with this conclusion. Together, these results support a model in which PI-PLC-γ1 provides DAG that binds to ϵC1B, facilitating PKC-ϵ localization to phagosomes for efficient IgG-mediated phagocytosis.

Mitogen stimulation of Na+-H+ exchange: differential involvement of protein kinase C

1987 ◽  
Vol 253 (2) ◽  
pp. C219-C229 ◽  
Author(s):  
L. L. Muldoon ◽  
G. A. Jamieson ◽  
A. C. Kao ◽  
H. C. Palfrey ◽  
M. L. Villereal
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Types ◽  
Intact Cells ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Human Fibroblast Strains ◽  
Stimulation Of

The mitogen-induced activation of Na+-H+ exchange was investigated in two cultured human fibroblast strains (HSWP and WI-38 cells) that, based on previous studies, differed in their response to the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) (L. M. Vincentini and M. L. Villereal, Proc. Natl. Acad. Sci. USA 82: 8053-8056, 1985). The role of protein kinase C in the activation of Na+-H+ exchange was investigated by comparing the effects of TPA on Na+ influx, in vitro phosphorylation, and in vivo phosphorylation in both cell types. Although both cell types have significant quantities of protein kinase C activity that can be activated by TPA in intact cells, the addition of TPA to intact cells stimulates Na+ influx in WI-38 cells but not in HSWP cells, indicating that in HSWP cells the stimulation of protein kinase C is not sufficient to activate the Na+-H+ exchanger. Cells were then depleted of protein kinase C activity by chronic treatment with high doses of TPA. Both HSWP and WI-38 cells were rendered protein kinase C deficient by this treatment as determined by in vitro and in vivo phosphorylation studies. Protein kinase C-deficient HSWP cells lose the ability for TPA to inhibit the serum-induced activation of Na+-H+ exchange, but there is no reduction in the stimulation of Na+ influx by serum, bradykinin, vasopressin, melittin, or vanadate, indicating that protein kinase C activity is not necessary for the mitogen-induced activation of Na+-H+ exchange in HSWP cells by agents known to stimulate phosphatidylinositol turnover (G. A. Jamieson and M. Villereal. Arch. Biochem. Biophys. 252: 478-486, 1987). In contrast, depletion of protein kinase C activity in WI-38 cells significantly reduces both the TPA- and the serum-induced activation of the Na+-H+ exchange system, suggesting that protein kinase C activity is necessary for at least a portion of the mitogen-induced activation of the Na+-H+ exchanger in WI-38 cells. These results indicate that the mechanisms for regulating Na+-H+ exchange can differ dramatically between different types of fibroblasts.

Leptin Constrains Phospholipase C-Protein Kinase C-Induced Insulin Secretion via a Phosphatidylinositol 3-Kinase-Dependent Pathway

2003 ◽  
Vol 228 (2) ◽  
pp. 175-182 ◽  
Author(s):  
Joo-Won Lee ◽  
Andrew G. Swick ◽  
Dale R. Romsos
Keyword(s):  
Protein Kinase C ◽  
Insulin Secretion ◽  
Protein Kinase ◽  
Phospholipase C ◽  
Phosphatidylinositol 3 Kinase ◽  
C Protein ◽  
Kinase C ◽  
Pka Pathway ◽  
Stimulation Of ◽  
Phosphatidylinositol 3

Leptin-deficient Lepob/Lepob mice hypersecrete insulin in response to acetylcholine stimulation of the phospholipase C-protein kinase C (PLC-PKC) pathway, and leptin constrains this hypersecretion. Leptin has been reported to activate phosphatidylinositol 3-kinase (PI 3-K) and subsequently phosphodiesterase (PDE) to impair protein kinase A (PKA)-induced insulin secretion from cultured islets of neonatal rats. We determined if PKA-induced insulin secretion was also hyperresponsive in Islets from Lepob/Lepob mice, and if leptin impaired this pathway in islets from these mice. Additionally, the possible role for PI 3-K and PDE in leptin-induced control of acetylcholine-induced insulin secretion was examined. Stimulation of Insulin secretion with GLP-1, forskolin (an activator of adenylyl cyclase), or IBMX (an inhibitor of PDE) did not cause hypersecretion of insulin from islets of young Lepob/Lepob mice, and leptin did not inhibit GLP-1-induced insulin secretion from islets of these mice. Inhibition of PDE with IBMX also did not block leptin-induced inhibition of acetylcholine-mediated insulin secretion from islets of Lepob/Lepob mice. But, preincubation of islets with wortmannin, an Inhibitor of PI 3-K activity, blocked the ability of leptin to constrain acetylcholine-induced insulin secretion from islets of Lepob/Lepob mice. We conclude that the capacity of the PKA pathway to stimulate insulin secretion is not increased in islets from young Lepob/Lepob mice, and that leptin does not regulate this pathway in islets from mice. Leptin may stimulate PI 3-K to constrain PLC-PKC-induced insulin secretion from Islets of Lepob/Lepob mice.

scholarly journals Phosphorylation of human pleckstrin on Ser-113 and Ser-117 by protein kinase C

1996 ◽  
Vol 314 (3) ◽  
pp. 937-942 ◽  
Author(s):  
Karen L. CRAIG ◽  
Calvin B. HARLEY
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phosphorylation Sites ◽  
Wild Type ◽  
Cos Cells ◽  
Phospholipid Hydrolysis ◽  
Kinase C

During platelet activation, receptor-coupled phospholipid hydrolysis stimulates protein kinase C (PKC) and results in the phosphorylation of several proteins, the most prominent being pleckstrin. Pleckstrin is composed of two repeated domains, now called pleckstrin homology (PH) domains, separated by a spacer region that contains several consensus PKC phosphorylation sites. To determine the role of PKC-dependent phosphorylation in pleckstrin function, we mapped the phosphorylation sites in vivo of wild-type and site-directed mutants of pleckstrin expressed in COS cells. Phosphorylation was found to occur almost exclusively on Ser-113 and Ser-117 within the sequence 108-KFARKS*TRRS*IRL-120. Phosphorylation of these sites was confirmed by phosphorylation of the corresponding wild-type and mutant synthetic peptides in vitro.

Phorbol esters inhibit ammoniagenesis and gluconeogenesis in proximal tubular segments

1987 ◽  
Vol 252 (6) ◽  
pp. F1073-F1079
Author(s):  
M. C. Chobanian ◽  
M. R. Hammerman
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Proximal Tubule ◽  
Phorbol Ester ◽  
Phorbol Esters ◽  
Extracellular Ph ◽  
Linear Functions ◽  
Kinase C ◽  
Proximal Tubular ◽  
Stimulation Of

To characterize the regulation of ammoniagenesis and gluconeogenesis in renal proximal tubule, ammonia and glucose productions were measured in suspensions of canine proximal tubular segments incubated with 10 mM L-glutamine. Productions were linear functions of time for 120 min and were decreased as extracellular pH was increased from 7.0 to 7.5 To ascertain whether activation of protein kinase c affects either process, we incubated segments with tumor-promoting phorbol esters, 12-O-tetradecanoylphorbol-13-acetate (TPA), or phorbol 12,13-dibutyrate, or with the inactive phorbol ester 4 alpha-phorbol. Ammoniagenesis and gluconeogenesis were inhibited by incubation with 10(-6) M of the two former compounds but not the latter compound. Inhibition of ammoniagenesis and gluconeogenesis occurred after incubation with as little as 10(-9) M phorbol 12,13-dibutyrate. Phorbol ester-induced inhibition was observed under conditions such that extracellular [Na+] was greater than intracellular [Na+], but not when extracellular [Na+] equaled intracellular [Na+], and was not observed in the presence of amiloride. Our findings are consistent with a role for protein kinase c in the control of ammoniagenesis and gluconeogenesis in proximal tubule. Such control could be mediated via stimulation of Na+-H+ exchange.

scholarly journals cAMP-dependent inhibition is dominant in regulating superoxide production in the bone-resorbing osteoclasts

1998 ◽  
Vol 158 (3) ◽  
pp. 311-318 ◽  
Author(s):  
CE Berger ◽  
BR Horrocks ◽  
HK Datta
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Pertussis Toxin ◽  
Kinase C ◽  
Significant Stimulation ◽  
Dependent Inhibition ◽  
Dependent Protein ◽  
O2 Production ◽  
Stimulation Of

Calciotropic hormones such as parathyroid hormone (PTH) and calcitonin have been shown to have stimulatory and inhibitory effects respectively on superoxide anion (O2-) generation by osteoclasts, but the exact intracellular signalling mediating these pathways has not been investigated. In order to elucidate the intracellular pathways controlling O2- generation, we have carried out a systematic study of the effect of different agents on O2- production in osteoclasts cultured on bovine cortical bone. Dibutyryl cAMP and cholera toxin, while having no effect on the basal level of O2- production in bone-resorbing osteoclasts, were, however, found to completely block the stimulation of free radical production by PTH, pertussis toxin and ionomycin. The stimulation of O2- production was found to be independent of protein kinase C-dependent pathways since the presence of bisindolylmaleimide (GF109203X) (1 microM) did not block stimulation by PTH and pertussis toxin. Interestingly, while exposure to bisindolylmaleimide at this concentration did not have any effect on the basal level of O2- production, exposure to a higher concentration (10 microM), which is known to inhibit both protein kinase C and A, produced significant stimulation. These in vitro findings suggest that in the bone-resorbing cells, cAMP-dependent protein kinases prevent further stimulation of NADPH oxidase by agents such as PTH and pertussis toxin. The increase in cAMP has also been recently demonstrated to be associated with down-regulation of the oxidative burst in adherent neutrophils; and the findings reported here suggest a similar role for cAMP in O2- generation in osteoclasts cultured on bone.

Adenosine A1 receptor-mediated inhibition of myocardial norepinephrine release involves neither phospholipase C nor protein kinase C but does involve adenylyl cyclase

2006 ◽  
Vol 84 (5) ◽  
pp. 573-577 ◽  
Author(s):  
Frank Schütte ◽  
Christof Burgdorf ◽  
Gert Richardt ◽  
Thomas Kurz
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Adenylyl Cyclase ◽  
Phospholipase C ◽  
Suppressive Effect ◽  
Inhibitory Effect ◽  
Direct Stimulation ◽  
Kinase C ◽  
Gf 109203X ◽  
Stimulation Of

Stimulation of adenosine A1 receptors in the heart exerts cardioprotective effects by inhibiting norepinephrine (NE) release from sympathetic nerve endings. The intraneuronal signal transduction triggered by presynaptic adenosine A1 receptors is still not completely understood. The objective of the present study was to determine whether phospholipase C (PLC), protein kinase C (PKC), and adenylyl cyclase (AC) are involved in the adenosine A1 receptor-mediated inhibition of endogenous (stimulation-induced) NE release in isolated Langendorff-perfused rat hearts as an approach to elucidate their role in the cardiovascular system. Activation of adenosine A1-receptors with 2-chloro-N6-cyclopentyladenosine (CCPA) decreased cardiac NE release by ~40%. Inhibition of PLC with 1-[6-[[(17b)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U 73122) as well as inhibition of PKC with 2-[1-(3-dimethylaminopropyl)indol-3-yl]-3-(indol-3-yl)maleimide (GF 109203X) slightly but significantly decreased NE release; however, the suppressive effect of CCPA on NE release was not modulated by U 73122 or GF 109203X. Blockade of AC with 9-(tetrahydro-2′-furyl)adenine (SQ 22536) reversed the inhibitory effect of CCPA on sympathetic neurotransmitter release irrespective of whether PKC was pharmacologically activated by phorbol 12-myristate 13-acetate or was not activated, indicating a PKC-independent but AC-dependent mechanism. Direct stimulation of AC with forskolin increased NE release by ∼20%; an effect that was antagonized by either CCPA or SQ 22536. These data suggest that the adenosine A1 receptor-mediated inhibition of NE release does not involve PLC or PKC but does involve AC.

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