Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phospholipase D (PLD) is distributed widely in mammalian tissues where it is believed to play an important role in the regulation of cell functions and cell fate by a variety of extracellular signals. In this study, we used primary cultures of rabbit connecting tubule (CNT) and cortical collecting duct (CCD) cells, grown to confluence on a permeable support, to investigate the possible involvement of PLD in the mechanism of action of hormones that regulate Ca(2+) reabsorption. RT-PCR revealed the presence of transcripts of PLD1b and PLD2, but not PLD1a, in these cultures. Moreover, the expression of substantial amounts of PLD1 protein was demonstrated by Western blotting. To measure PLD activity, cells were labelled with [(3)H]myristic acid after which the PLD-catalysed formation of radiolabelled phosphatidylethanol ([(3)H]PtdEth) was measured in the presence of 1% (v/v) ethanol. Deamino-Cys,D-Arg(8)-vasopressin (dDAVP) and N(6)-cyclopentyladenosine (CPA), two potent stimulators of Ca(2+) transport across these monolayers, stimulated PLD activity as was indicated by a marked increase in [(3)H]PtdEth. Similarly, ATP, a potent inhibitor of dDAVP- and CPA-stimulated Ca(2+) transport, increased the formation of [(3)H]PtdEth. PLD activity was furthermore increased by 8Br-cAMP and following acute (30 min) stimulation of protein kinase C (PKC) with a phorbol ester (PMA). Chronic PMA treatment (120 h) to downregulate phorbol ester-sensitive PKC isoforms did not affect PLD activation by dDAVP, CPA and 8Br-cAMP, while markedly decreasing the effect of ATP and abolishing the effect of PMA. The PKC inhibitor chelerythrine significantly reduced PLD activation by dDAVP, CPA and 8Br-cAMP, without changing the effect of ATP. The inhibitor only partially reduced the effect of PMA. This study shows that Ca(2+) transporting cells of CNT and CCD contain a regulated PLD activity. The physiological relevance of this activity, which is not involved in Ca(2+) reabsorption, remains to be established.
 ...
PMID:Hormonal regulation of phospholipase D activity in Ca(2+) transporting cells of rabbit connecting tubule and cortical collecting duct. 1133 4

1. Madin-Darby canine kidney (MDCK) cells, a well- differentiated renal epithelial cell line derived from distal tubule/collecting duct, respond to extracellular nucleotides by altering ion flux and the production of arachidonic acid-derived products, in particular prostaglandin E2 (PGE2). Our work has defined the receptors and signalling events involved in such responses. 2. We have found evidence for expression of at least three P2Y receptor subtypes (P2Y1, P2Y2 and P2Y11) in MDCK-D1 cells, a subclone from parental MDCK. 3. These receptors appear to couple to increases in calcium and protein kinase C activity, probably via a Gq/G11-mediated activation of phospholipase C. 4. In addition, P2Y receptor activation can promote a prominent increase in cAMP. This includes both a P2Y2 receptor-mediated cyclo-oxygenase (COX)-dependent component and another COX-independent component mediated by other P2Y receptors. 5. We have documented that changing media in which cells are grown releases ATP and, in turn, activates P2Y receptors. Such release of ATP contributes in a major way to basal cAMP levels in these cells. 6. The data indicate that MDCK cells are a useful model to define the regulation of epithelial cells by extracellular nucleotides. Of particular note, spontaneous or stretch-induced release of ATP and subsequent activation of one or more P2Y receptors contributes to establishing the basal activity of signalling pathways.
 ...
PMID:P2Y receptors of MDCK cells: epithelial cell regulation by extracellular nucleotides. 1133 12

Hepatocyte growth factor (HGF) has been shown to enhance recovery from renal tubular ischemia. We investigated the possibility that HGF improves recovery by preventing ischemia-induced loss of cell adhesion. Murine inner medullary collecting duct-3 (mIMCD-3) cells subjected to 90% ATP depletion demonstrated a 55% decrease in adhesion, an effect that was completely reversed by the addition of HGF. Assays examining release of adherent cells revealed similar results with 30 min of ATP depletion causing loss of adhesion of 25% of mIMCD-3 cells and HGF completely reversing this effect. In contrast, HGF was unable to reverse the loss of adhesion of cells exposed to 99% ATP depletion. Examination of the mitogen-activated protein kinase (MAPK) signaling pathway revealed that HGF could induce extracellular signal-regulated kinase (ERK) phosphorylation in control and 90% ATP-depleted cells but not in 99% ATP-depleted cells. Inhibition of ERK activation with U0126 completely blocked the HGF-dependent reversal of ATP-depleted cell adhesion. Thus ATP-depleted cells demonstrate a marked decrease in cell adhesion that is reversible by the addition of HGF. This effect of HGF requires activation of the MAPK pathway.
 ...
PMID:HGF promotes adhesion of ATP-depleted renal tubular epithelial cells in a MAPK-dependent manner. 1139 47

In this study, the distribution of P2Y(6) receptor mRNA in rat nephron segments was investigated and a functional approach was used to analyze basolateral protein expression. Reverse transcription-PCR studies revealed more intense expression of P2Y(6) receptor mRNA in the proximal tubule and the thick ascending limb of Henle's loop, less intense expression in the thin descending limb and the cortical and outer medullary collecting ducts, and no detectable expression in either the thin ascending limb or the inner medullary collecting duct. Dose-dependent calcium responses to basolateral administration of UDP (a selective agonist for the P2Y(6) receptor) were observed in the proximal tubule but not in any of the other segments studied. In the proximal tubule, intracellular calcium concentration changes induced by UDP were associated with increased production of inositol phosphates, as were those induced by ATP and norepinephrine. However, UDP-induced intracellular calcium concentration changes were different, exhibiting no plateau after the initial peak; moreover, a single stimulation with a high concentration of UDP induced full desensitization of the UDP-sensitive calcium pathway but did not alter the responsiveness of the proximal tubule to ADP (a specific P2Y(1) receptor agonist), ATP or norepinephrine. In summary, this report demonstrates that P2Y(6) receptor mRNA is expressed in most segments of the rat nephron but that basolateral expression of the protein is restricted to the proximal tubule, where the receptor is coexpressed with the P2Y(1) receptor. The differences in the distributions of P2Y(6) receptor mRNA and UDP responses may indicate the presence of luminal receptors in other nephron segments.
 ...
PMID:Evidence for basolateral P2Y(6) receptors along the rat proximal tubule: functional and molecular characterization. 1146 36

Aldosterone is involved in salt and water homeostasis. The main effect is thought to involve genomic mechanisms. However, the existence of plasma membrane steroid receptors has been postulated. We used whole cell patch clamp to test the hypothesis that epithelial sodium channels (ENaC) expressed by renal collecting duct principal cells can be regulated nongenomically by aldosterone. In freshly isolated principal cells from rabbit, aldosterone (100 nM) rapidly (<2 min) increased ENaC sodium current specifically. The aldosterone-activated current was completely inhibited by amiloride. Aldosterone also activated ENaC in cells treated with the mineralocorticoid receptor blocker spiranolactone. Nongenomic activation was inhibited by inclusion of S-adenosyl-L-homocysteine in the pipette solution, which inhibits methylation reactions. Also, the nongenomic activation required 2 mM ATP supplementation in the pipette solution. Aldosterone did not activate any ENaC current in whole cell clamped rat collecting duct principal cells. These functional studies are consistent with aldosterone membrane binding studies, suggesting the presence of a plasma membrane steroid receptor that affects cellular processes by mechanisms unrelated to altered gene expression.
 ...
PMID:Nongenomic regulation of ENaC by aldosterone. 1154 44

Extracellular nucleotides modulate renal ion transport. Our previous results in M-1 cortical collecting duct cells indicate that luminal and basolateral ATP via P2Y2 receptors stimulate luminal Ca2+-activated Cl- channels and inhibit Na+ transport. Here we address the mechanism of ATP-mediated inhibition of Na+ transport. M-1 cells had a transepithelial voltage (V(te)) of -31.4 +/- 1.3 mV and a transepithelial resistance (R(te)) of 1151 +/- 28 Omegacm(2). The amiloride-sensitive short circuit current (I(sc)) was -28.0 +/- 1.1 microA/cm2. The ATP-mediated activation of Cl- channels was inhibited when cytosolic Ca2+ increases were blocked with cyclopiazonic acid (CPA). Without CPA the ATP-induced [Ca2+](i) increase was paralleled by a rapid and transient R(te) decrease (297 +/- 51 Omegacm(2)). In the presence of CPA, basolateral ATP led to an R(te) increase by 144 +/- 17 Omegacm(2) and decreased V(te) from -31 +/- 2.6 to -26.6 +/- 2.5 mV. Isc dropped from -28.6 +/- 2.4 to -21.6 +/- 1.9 microA/cm2. Similar effects were observed with luminal ATP. In the presence of amiloride, ATP was without effect. This reflects ATP-mediated inhibition of Na+ absorption. Lowering [Ca2+](i) by removal of extracellular Ca2+ did not alter the ATP effect. PKC inhibition or activation were without effect. Na+ absorption was activated by pH(i) alkalinization and inhibited by pH(i) acidification. ATP slightly acidified M-1 cells by 0.05 +/- 0.005 pH units, quantitatively not explaining the ATP-induced effect. In summary this indicates that extracellular ATP via luminal and basolateral P2Y2 receptors inhibits Na+ absorption. This effect is not mediated via [Ca2+](i), does not involve PKC and is to a small part mediated via intracellular acidification.
 ...
PMID:P2Y(2) receptor-mediated inhibition of amiloride-sensitive short circuit current in M-1 mouse cortical collecting duct cells. 1156 93

We established six renal tubular cell lines from definite tubular areas of the kidney of transgenic mice harboring tsSV40 large T-antigen gene. Three are proximal tubular cell lines prepared from the S(1), S(2) and S(3) segments of the proximal tubule and the others are collecting duct cell lines obtained from cortical, outer medullary and inner medullary collecting ducts (CCD, OMCD and IMCD, respectively). To verify the growth properties of these cell lines under different temperature conditions (33 and 39 degrees C), two representative cells were chosen from the proximal tubule (S(1) cells) and from the collecting duct (IMCD cells). From these cells, a daily change in cell number was evaluated as a parameter of cell growth. As might be expected, cell numbers of these cells increased only at 33 degrees C. Similar patterns were also observed with the other cell lines. To observe the different sensitivity to nephrotoxic agents in proximal tubular cell lines, the cells were exposed to nephrotoxic agent, gentamicin, ochratoxin A or cisplatin. Gentamicin (1 mg/ml) dose-dependently decreased cellular ATP levels of the S(1) cells only. In contrast, the effect of ochratoxin A (10(-6) M) was most pronounced in the S(2) cells, and that of cisplatin (10 microg/ml) in the S(3) cells. To characterize collecting duct cell lines, a hyperosmotic challenge of 700 or 1100 mOsm/l was applied to the cells. At an isoosmotic condition of 300 mOsm/l, the number of cells from the collecting ducts, regardless of their origin, increased continuously during the culture period of 4 days. At an osmotic concentration of 700 mOsm/l, the number of CCD cells decreased, while OMCD cells showed a gradual but a significant increase in cell numbers throughout the culture period. IMCD cells, however, proliferated even at a concentration as high as 1100 mOsm/l, although an initial decrease in cell number was noted on the first day of culture. For confirmation of intracellular free calcium ([Ca(2+)](i)) mobilization, cells were treated with ATP and bradykinin. The [Ca(2+)](i) was increased significantly and immediately by ATP (10(-4) M) in S(1) cells and bradykinin (10(-7) M) in IMCD cells. From the results obtained, it is indicated that renal tubular cell lines from transgenic mice have different sensitivities to nephrotoxic or osmotic stress showing the conservation of the functional characters of the definite part it originated from.
 ...
PMID:Different sensitivity to nephrotoxic agents and osmotic stress in proximal tubular and collecting duct cell lines derived from transgenic mice. 1181 40

Na(+)/H(+) exchanger (NHE) proteins perform a variety of functions in the kidney and are differentially distributed among nephron segments. The purpose of this study was to identify NHE isoforms in murine M-1 cells as a model of cortical collecting duct principal cells. It was found that mRNAs corresponding to NHE1, NHE2, and NHE4 are expressed in M-1 cells. NHE-dependent regulation of intracellular pH (pH(i)) was investigated in the absence of extracellular HCO. Application of a 20 mM NH(4)Cl pulse resulted in a reversible intracellular acidification from which recovery was partially inhibited by application of 1 mM amiloride to either the apical or the basolateral membranes and was abolished when amiloride was applied to both sides of the monolayers, which suggests that NHEs are expressed in both the apical and the basolateral cell membranes of M-1 cells. The purinergic agonists ATP and benzoylbenzoyl-ATP caused a reduction of pH(i) when applied to the apical membrane, which suggests pH(i) may be influenced by extracellular nucleotides in the luminal fluid of the cortical collecting duct.
 ...
PMID:Expression of isoforms of the Na(+)/H(+) exchanger in M-1 mouse cortical collecting duct cells. 1188 Mar 26

Previous studies have shown that basolateral ATP inhibits vasopressin action in the renal collecting tubule. Although there is evidence for an apical P2Y2 receptor in this tubule segment, it is not known whether apical ATP has similar effects. In the rat inner medullary collecting duct basolateral, but not apical, ATP (0.1-100 microM) reversibly inhibited vasopressin-induced increases in water permeability with an IC50 of 1.09 microM. Basolateral UTP, but not ADP, alpha,beta-methylene-ATP or 2-methylthio-ATP also inhibited vasopressin action. It is concluded that basolateral but not apical P2Y2 receptors inhibit vasopressin action in the collecting duct.
 ...
PMID:Basolateral, but not apical, ATP inhibits vasopressin action in rat inner medullary collecting duct. 1190 9

Raising osmolality to 700 mosmol/kgH(2)O by the addition of NaCl rapidly kills most murine inner renal medullary collecting duct cells (mIMCD3), but they survive at 500 mosmol/kgH(2)O. At 300 and 500 mosmol/kgH(2)O, NADH autofluorescence is present in a mitochondria-associated, punctate perinuclear pattern. Within 45 s to 30 min at 700 mosmol/kgH(2)O, the autofluorescence spreads diffusely throughout the cell. This correlates with mitochondrial membrane depolarization, measured as decreased tetramethylrhodamine methyl ester perchlorate (TMRM) fluorescence. Mitochondrial dysfunction should increase the cellular ADP/ATP ratio. In agreement, this ratio increases within 1-6 h. Mitochondrial morphology (transmission electron microscopy) is unaffected, but nuclear hypercondensation becomes evident. Progressive apoptosis occurs beginning 1 h after osmolality is raised to 700, but not to 500, mosmol/kgH(2)O. General caspase activity and caspase-9 activity increase only after 6 h at 700 mosmol/kgH(2)O. The mitochondrial Bcl-2/Bax ratio decreases within 1-3 h, but no cytochrome c release is evident. The mitochondria contain little p53 at any osmolality. Adding urea to 700 mosmol/kgH(2)O does not change NADH or TMRM fluorescence. We conclude that extreme acute hypertonicity causes a mitochondrial dysfunction involved in the initiation of apoptosis.
 ...
PMID:Mitochondrial dysfunction is an early event in high-NaCl-induced apoptosis of mIMCD3 cells. 1199 14


<< Previous 1 2 3 4 5 6 7 8 9 10