Effects of CGRP, forskolin, PMA, and ionomycin on pHi dependence of Na-H exchange in UMR-106 cells

1994 ◽  
Vol 266 (4) ◽  
pp. C1083-C1092 ◽  
Author(s):  
Anandarup Gupta ◽  
Christof J. Schwiening ◽  
Walter F. Boron
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Acid Base Balance ◽  
Total Acid ◽  
Molecular Physiology ◽  
Cyclic Monophosphate ◽  
Kinase C ◽  
Base Balance ◽  
The Difference ◽  
Umr 106

1 Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510 We examined the effects of calcitonin gene-related peptide (CGRP), forskolin, phorbol 12-myristate 13-acetate (PMA), and ionomytin on the intracellular pH (pHi) dependence of Na-H exchange in UMR-106 cells. In the nominal absence of CO2-HCO3-, each agent increased pHi, measured with 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). From the rate of pHi recovery (dpHi/dt) from an acid load, and intracellular buffering power, we computed the pHi dependence of the total acid-extruding flux (JTotal). All four agents increased JTotal. From dpHi/dt data obtained in the presence of ethylisopropyl amiloride (EIPA, a blocker of Na-H exchange), we determined the EIPA-resistant component of JTotal (JEIPA/R). We estimated the Na-H exchange flux (JNa-H as the difference JTotal - JEIPA/R. CGRP, forskolin, and PMA produced similar increases in the slope of the JNa-H vs. pHi-relationship. The net effect of these agents, as well as ionomycin, was to increase JNa-H over a broad pHi range. Ionomycin alkaline shifted the JEIPA/R vs. pHi relationship; the other agents had no effect. Our results indicate that CGRP increased JTotal by stimulating Na-H exchange, with little effect on EIPA-resistant processes. A signaling pathway involving only adenosine 3',5'-cyclic monophosphate, only protein kinase C, or only Ca2+ cannot account for the effects of CGRP on both pHi and pHi dependence of JNa-H. Thus, CGRP probably affects UMR-106 pHi physiology via more than one pathway. acid-base balance; ion transport; ethylisopropyl amiloride; amiloride analogs; osteoblasts; fluorescence; 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein; calcium; adenosine 3',5'-cyclic monophosphate; protein kinase C Submitted on February 19, 1993 Accepted on October 8, 1993

Genistein and tyrphostin 47 stimulate CFTR-mediated Cl- secretion in T84 cell monolayers

1995 ◽  
Vol 269 (6) ◽  
pp. G874-G882 ◽  
Author(s):  
C. L. Sears ◽  
F. Firoozmand ◽  
A. Mellander ◽  
F. G. Chambers ◽  
I. G. Eromar ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Secretory Pathway ◽  
Kinase Inhibitors ◽  
T84 Cells ◽  
Cl Secretion ◽  
Cyclic Monophosphate ◽  
3T3 Fibroblasts ◽  
Kinase C

The involvement of tyrosine phosphorylation in the regulation of epithelial cell Cl- secretion is unknown. Therefore, the purpose of these studies was to determine if tyrosine kinase activation was involved in the regulation of Cl- secretion, using the tyrosine kinase inhibitors, genistein and tyrphostin 47, and human intestinal epithelial cells (T84 cells) as an intestinal Cl- secretory model. Genistein rapidly but reversibly stimulated sustained apical Cl- secretion in monolayers of T84 cells without increasing intracellular cyclic nucleotides or Ca2+ levels. Tyrphostin 47 also stimulated Cl- secretion in T84 monolayers, although it was short-lived. Transfection experiments in 3T3 fibroblasts and IEC-6 intestinal cells utilizing wild-type cystic fibrosis transmembrane conductance regulator (CFTR) showed that genistein and tyrphostin 47 stimulated 125I efflux only in CFTR-transfected cells and not in CFTR-negative cells. Thus genistein- and tyrphostin 47-stimulated Cl- secretion involved CFTR. Genistein also acted synergistically with the Ca(2+)- and protein kinase C-dependent acetylcholine analogue, carbachol, to stimulate Cl- secretion in T84 monolayers. However, the Cl- secretory response to saturating concentrations of the adenosine 3',5'-cyclic monophosphate (cAMP) agonist, forskolin, or the guanosine 3',5'-cyclic monophosphate (cGMP) agonist, Escherichia coli heat-stable enterotoxin, was not further enhanced by genistein. Although the mechanism of activation of Cl- secretion is unclear, these data suggest that tyrosine kinase activity limits basal Cl- secretion in T84 cells and that inhibition of T84 cell tyrosine kinase(s) stimulates apical membrane Cl- secretion, most likely through activation of the CFTR-Cl- channel. Moreover, genistein does not itself act through cAMP or cGMP elevation but appears to share a common Cl- secretory pathway with cyclic nucleotide-dependent agonists, whereas it augments the secretory responses to a Ca(2+)- and protein kinase C-dependent agonist.

The role of protein kinase C-δ in PTH stimulation of IGF-binding protein-5 mRNA in UMR-106–01 cells

2002 ◽  
Vol 282 (3) ◽  
pp. E534-E541 ◽  
Author(s):  
Mary S. Erclik ◽  
Jane Mitchell
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Binding Protein ◽  
Specific Inhibitor ◽  
Dominant Negative Mutant ◽  
Nuclear Fraction ◽  
Mrna Levels ◽  
Kinase C ◽  
Umr 106

We have investigated the role of protein kinase C (PKC) signal transduction pathways in parathyroid hormone (PTH) regulation of insulin-like growth factor-binding protein-5 (IGFBP-5) gene expression in the rat osteoblast-like cell line UMR-106–01. Involvement of the PKC pathway was determined by the findings that bisindolylmaleimide I inhibited 40% of the PTH effect, and 1 μM bovine PTH-(3–34) stimulated a 10-fold induction of IGFBP-5 mRNA. PTH-(1–34) and PTH-(3–34) (100 nM) both stimulated PKC-δ translocation from the membrane to the nuclear fraction. Rottlerin, a PKC-δ-specific inhibitor, and a dominant negative mutant of PKC-δ were both able to significantly inhibit PTH-(1–34) and PTH-(3–34) induction of IGFBP-5 mRNA, suggesting a stimulatory role for PKC-δ in the effects of PTH. Phorbol 12-myristate 13-acetate (PMA) stimulated PKC-α translocation from the cytosol to the membrane and inhibited ∼50% of the PTH-(1–34), forskolin, and 8-bromoadenosine 3′,5′-cyclic monophosphate-stimulated IGFBP-5 mRNA levels, suggesting that PKC-α negatively regulates protein kinase A (PKA)-mediated induction of IGFBP-5 mRNA. These results suggest that the induction of IGFBP-5 by PTH is both PKA and PKC dependent and PKC-δ is the primary mediator of the effects of PTH via the PKC pathway.

Bidirectional modulation of parathyroid hormone-responsive adenylyl cyclase by protein kinase C

1994 ◽  
Vol 266 (6) ◽  
pp. E897-E904 ◽  
Author(s):  
A. M. Kitten ◽  
T. K. Hymer ◽  
M. S. Katz
Keyword(s):  
Protein Kinase C ◽  
Parathyroid Hormone ◽  
Protein Kinase ◽  
Adenylyl Cyclase ◽  
Catalytic Subunit ◽  
Mrna Levels ◽  
Binding Studies ◽  
Kinase C ◽  
Bidirectional Modulation ◽  
Umr 106

The temporal pattern with which phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C (PKC), modulates parathyroid hormone (PTH)-responsive adenylyl cyclase (AC) was evaluated in a clonal osteoblast-like cell line (UMR-106). Brief (< or = 1 h) exposure of UMR-106 cells to PMA enhanced PTH stimulation of AC, whereas more prolonged PMA treatment decreased the PTH response, with maximum inhibition occurring at < or = 6 h. PMA treatment also resulted in initial activation followed by downregulation of PKC. Exposure of cells to 1,2-dioctanoyl-sn-glycerol, which activated but did not downregulate PKC, resulted in bidirectional modulation of PTH-responsive AC identical to that produced by PMA. Prolonged PMA exposure decreased PTH receptor number, as determined by radioligand binding studies, and reduced PTH receptor mRNA levels, assessed by Northern blot analysis. Forskolin activation of the catalytic subunit of AC was also decreased after prolonged PMA treatment. The results suggest that activation of PKC sequentially stimulates and then inhibits PTH responsiveness. Inhibition of the PTH response occurs by PKC actions exerted on the PTH receptor and the AC catalytic subunit.

scholarly journals Cytosolic pH regulation in osteoblasts. Regulation of anion exchange by intracellular pH and Ca2+ ions.

1990 ◽  
Vol 95 (1) ◽  
pp. 121-145 ◽  
Author(s):  
J Green ◽  
D T Yamaguchi ◽  
C R Kleeman ◽  
S Muallem
Keyword(s):  
Protein Kinase C ◽  
Membrane Potential ◽  
Protein Kinase ◽  
Anion Exchange ◽  
Cytosolic Ph ◽  
Subsequent Recovery ◽  
Kinase C ◽  
Recovery From Acidification ◽  
Umr 106 ◽  
Cytosolic Acidification

Measurements of cytosolic pH (pHi) 36Cl fluxes and free cytosolic Ca2+ concentration ([Ca2+]i) were performed in the clonal osteosarcoma cell line UMR-106 to characterize the kinetic properties of Cl-/HCO3- (OH-) exchange and its regulation by pHi and [Ca2+]i. Suspending cells in Cl(-)-free medium resulted in rapid cytosolic alkalinization from pHi 7.05 to approximately 7.42. Subsequently, the cytosol acidified to pHi 7.31. Extracellular HCO3- increased the rate and extent of cytosolic alkalinization and prevented the secondary acidification. Suspending alkalinized and Cl(-)-depleted cells in Cl(-)-containing solutions resulted in cytosolic acidification. All these pHi changes were inhibited by 4',4',-diisothiocyano-2,2'-stilbene disulfonic acid (DIDS) and H2DIDS, and were not affected by manipulation of the membrane potential. The pattern of extracellular Cl- dependency of the exchange process suggests that Cl- ions interact with a single saturable external site and HCO3- (OH-) complete with Cl- for binding to this site. The dependencies of both net anion exchange and Cl- self-exchange fluxes on pHi did not follow simple saturation kinetics. These findings suggest that the anion exchanger is regulated by intracellular HCO3- (OH-). A rise in [Ca2+]i, whether induced by stimulation of protein kinase C-activated Ca2+ channels, Ca2+ ionophore, or depolarization of the plasma membrane, resulted in cytosolic acidification with subsequent recovery from acidification. The Ca2+-activated acidification required the presence of Cl- in the medium, could be blocked by DIDS, and H2DIDS and was independent of the membrane potential. The subsequent recovery from acidification was absolutely dependent on the initial acidification, required the presence of Na+ in the medium, and was blocked by amiloride. Activation of protein kinase C without a change in [Ca2+]i did not alter pHi. Likewise, in H2DIDS-treated cells and in the absence of Cl-, an increase in [Ca2+]i did not activate the Na+/H+ exchanger in UMR-106 cells. These findings indicate that an increase in [Ca2+]i was sufficient to activate the Cl-/HCO3- exchanger, which results in the acidification of the cytosol. The accumulated H+ in the cytosol activated the Na+/H+ exchanger. Kinetic analysis of the anion exchange showed that at saturating intracellular OH-, a [Ca2+]i increase did not modify the properties of the extracellular site. A rise in [Ca2+]i increased the apparent affinity for intracellular OH- (or HCO3-) of both net anion and Cl- self exchange. These results indicate that [Ca2+]i modifies the interaction of intracellular OH- (or HCO3-) with the proposed regulatory site of the anion exchanger in UMR-106 cells.

Modification of Na+/H+ Exchanger in Human Platelets by 1,2-Dioctanoylglycerol, a Protein Kinase C Activator

1990 ◽  
Vol 64 (01) ◽  
pp. 165-171 ◽  
Author(s):  
Yukio Ozaki ◽  
Yuki Mastsumoto ◽  
Yutaka Yatomi ◽  
Masaaki Higashihara
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Rate Constant ◽  
Human Platelets ◽  
Kinase C ◽  
Km Value ◽  
The Difference ◽  
The One ◽  
Protein Kinase C Activation

SummaryProtein kinase C activation in human platelets has a modulatory role in maintaining intracellular pH (pHi), by adjusting pHi at a particular value (7.22). Changes in pHi induced by protein kinase C appeared to be dependent upon the difference between H+ efflux catalyzed by the Na+/H+ exchanger and H+ production. The pHi recovery after acid loading was significantly facilitated by protein kinase C activation. Analysis of the rate constant for pHi recovery suggested that the turnover rate or the apparent affinity of the Na+/H+ exchanger for H+ was increased. Protein kinase C also decreased the Km value of the Na+/H+ exchanger for extracellular Na+. Thus, it is suggested that the role of protein kinase C in platelet pHi regulation is dual, adjusting the pHi value at a certain setpoint on the one hand, and increasing the rate constant of the Na+/H+ exchanger on the other.

Protein kinase C differentially modulates PTH- and PGE2-sensitive adenylate cyclase in osteoblast-like cells

1992 ◽  
Vol 262 (1) ◽  
pp. E87-E95
Author(s):  
A. M. Freyaldenhoven ◽  
G. E. Gutierrez ◽  
M. D. Lifschitz ◽  
M. S. Katz
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Adenylate Cyclase ◽  
Enzyme Activation ◽  
Catalytic Subunit ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Osteosarcoma Cell ◽  
Kinase C ◽  
Umr 106

The effects of phorbol 12-myristate 13-acetate (PMA), a known activator of protein kinase C, on receptor-mediated stimulation of adenylate cyclase were evaluated in a rat osteosarcoma cell line (UMR-106) with the osteoblast phenotype. Pretreatment of UMR-106 cells with PMA increased parathyroid hormone (PTH)-stimulated adenylate cyclase activity and inhibited prostaglandin E2 (PGE2)-responsive enzyme activity. In addition, PMA enhanced enzyme activation by forskolin, which is thought to exert a direct stimulatory action on the catalytic subunit of adenylate cyclase. The regulatory effects of PMA were concentration dependent and of rapid onset (less than or equal to 1 min). Treatment with PMA also resulted in translocation of protein kinase C activity from the cytosol to the particulate cell fraction. Pertussis toxin, which attenuates inhibition of adenylate cyclase mediated by the inhibitory guanine nucleotide-binding regulatory protein (Gi), augmented PTH-sensitive adenylate cyclase activity and reduced the incremental increase in PTH response produced by PMA. The results suggest that activation of protein kinase C increases PTH-stimulated adenylate cyclase activity by actions on Gi and/or the catalytic subunit and decreases PGE2 responsiveness by a mechanism involving the PGE2 receptor.

Mechanisms by which endothelin 1 induces pulmonary vasoconstriction in the rabbit

1991 ◽  
Vol 71 (2) ◽  
pp. 410-416 ◽  
Author(s):  
J. Mann ◽  
I. S. Farrukh ◽  
J. R. Michael
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Rabbit Lung ◽  
Endothelin 1 ◽  
Cyclic Monophosphate ◽  
Pulmonary Vasoconstriction ◽  
Kinase C ◽  
Thromboxane Synthase Inhibitor ◽  
Calcium Availability ◽  
Synthase Inhibitor

To investigate the mechanisms by which endothelin 1 (ET-1) causes pulmonary vasoconstriction, we studied the effect of synthetic ET-1 on pulmonary vascular tone in the buffer-perfused isolated rabbit lung. In nanomolar concentrations (1.2–8 nM), ET-1 causes a dose-dependent increase in pulmonary arterial pressure that persists for greater than or equal to 1 h (increase in pressure 19 +/- 2 mmHg with ET-1 vs. 2 +/- 1 with vehicle, P less than 0.0001). Reduction of calcium availability with verapamil, cadmium, or a calcium-free buffer significantly blunts the increase in pressure caused by ET-1. Pretreatment with a calcium-free buffer plus the chelator ethylene glycol-bis(beta-aminoethyl ether)-N,N,N′, N′-tetraacetic acid (EGTA) completely eliminates the vasoconstriction. Three different inhibitors of protein kinase C, phloretin, staurosporine, and dihydrosphingosine, significantly diminish the response to ET-1. Indomethacin and a thromboxane synthase inhibitor partially decrease the response to the highest concentration of ET-1. Isoproterenol and dibutyryl adenosine 3′,5′-cyclic monophosphate (cAMP) are significantly more effective in preventing the vasoconstriction caused by ET-1 than are nitroprusside and guanosine 5′-cyclic monophosphate (cGMP) analogues. ET-1 in doses of 1.2–8 nM is a potent pulmonary vasoconstrictor in the isolated rabbit lung. ET-1 appears to cause pulmonary vasoconstriction by increasing calcium entry and by activating protein kinase C. Vasodilators that increase cAMP are substantially more effective in preventing the increase in pressure than are drugs that increase cGMP.

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