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Jacques Teulon

Publications and source records attributed to Jacques Teulon.

11 recordsLinked to original sources
PubMed2006

Similar chloride channels in the connecting tubule and cortical collecting duct of the mouse kidney.

Using the patch-clamp technique, we investigated Cl- channels on the basolateral membrane of the connecting tubule (CNT) and cortical collecting duct (CCD). We found a approximately 10-pS channel in CNT cell-attached patches. Substitution of sodium gluconate for NaCl in the pipette shifted the reversal potential by +25 mV, whereas N-methyl-D-gluconate chloride had no effect, indicating anion selectivity. On inside-out patches, we determined a selectivity sequence of Cl- > Br- approximately NO3(-) > F-, which is compatible with that of ClC-K2, a Cl- channel in the distal nephron. In addition, the number of open channels (NP(o)) measured in cell-attached patches was significantly increased when Ca2+ concentration or pH in the pipette was increased, which is another characteristic of ClC-K. These findings suggest that the basis for this channel is ClC-K2. A similar Cl- channel was found in CCD patches. Because CNT and CCD are heterogeneous tissues, we studied the cellular distribution of the Cl- channel using recording conditions (KCl-rich solution in the pipette) that allowed us to detect simultaneously Cl- channels and inwardly rectifying K+ channels. We detected Cl- channels alone in 45% and 42% and K+ channels alone in 51% and 58% of CNT and CCD patches, respectively. Cl- and K+ channels were recorded simultaneously from two patches (4% of patches) in the CNT and from none of the patches in the CCD. This indicates that Cl- and K+ channels are located in different cell types, which we suggest may be the intercalated cells and principal cells, respectively.

Animals↗
PubMed2006

A Na+- and Cl- -activated K+ channel in the thick ascending limb of mouse kidney.

This study investigates the presence and properties of Na+-activated K+ (K(Na)) channels in epithelial renal cells. Using real-time PCR on mouse microdissected nephron segments, we show that Slo2.2 mRNA, which encodes for the K(Na) channels of excitable cells, is expressed in the medullary and cortical thick ascending limbs of Henle's loop, but not in the other parts of the nephron. Patch-clamp analysis revealed the presence of a high conductance K+ channel in the basolateral membrane of both the medullary and cortical thick ascending limbs. This channel was highly K+ selective (P(K)/P(Na) approximately 20), its conductance ranged from 140 to 180 pS with subconductance levels, and its current/voltage relationship displayed intermediate, Na+-dependent, inward rectification. Internal Na+ and Cl- activated the channel with 50% effective concentrations (EC50) and Hill coefficients (nH) of 30 +/- 1 mM and 3.9 +/- 0.5 for internal Na+, and 35 +/- 10 mM and 1.3 +/- 0.25 for internal Cl-. Channel activity was unaltered by internal ATP (2 mM) and by internal pH, but clearly decreased when internal free Ca2+ concentration increased. This is the first demonstration of the presence in the epithelial cell membrane of a functional, Na+-activated, large-conductance K+ channel that closely resembles native K(Na) channels of excitable cells. This Slo2.2 type, Na+- and Cl--activated K+ channel is primarily located in the thick ascending limb, a major renal site of transcellular NaCl reabsorption.

Adenosine Triphosphate↗
PubMed2005

Hyperaldosteronemia and activation of the epithelial sodium channel are not required for sodium retention in puromycin-induced nephrosis.

Edema and ascites in nephrotic syndrome mainly result from increased Na+ reabsorption along connecting tubules and cortical collecting ducts (CCD). In puromycin aminonucleoside (PAN)-induced nephrosis, increased Na+ reabsorption is associated with increased activity of the epithelial sodium channel (ENaC) and Na+,K+-ATPase, two targets of aldosterone. Because plasma aldosterone increases in PAN-nephrotic rats, the aldosterone dependence of ENaC activation in PAN nephrosis was investigated. For this purpose, (1) the mechanism of ENaC activation was compared in nephrotic and sodium-depleted rats, and (2) ENaC activity in PAN-nephrotic rats was evaluated in the absence of hyperaldosteronemia. The mechanism of ENaC activation was similar in CCD from nephrotic and sodium-depleted rats, as demonstrated by (1) increased number of active ENaC evaluated by patch clamp, (2) recruitment of ENaC to the apical membrane determined by immunohistochemistry, (3) shift in the electrophoretic profile of gamma-ENaC, and (4) increased abundance of beta-ENaC mRNA. Corticosteroid clamp fully prevented all PAN-induced changes in ENaC but did not alter the development of a full-blown nephrotic syndrome with massive albuminuria, amiloride-sensitive sodium retention, induction of CCD Na+,K+-ATPase, and ascites. It is concluded that in PAN-nephrosis, (1) ENaC activation in CCD is secondary to hyperaldosteronemia, (2) sodium retention and induction of Na+,K+-ATPase in CCD are independent of hyperaldosteronemia, and (3) ENaC is not necessarily limiting for sodium reabsorption in the distal nephron.

Animals↗
PubMed2005

Misprocessing of the CFTR protein leads to mild cystic fibrosis phenotype.

Cystic fibrosis (CF) is mainly caused by mutations that interfere with the biosynthetic folding of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. The aim of this study was to determine the mechanism of dysfunction of a disease-causing mutation associated with variable phenotypes. In order to attain these objectives, we studied the effect of the p.L206W mutation on CFTR protein production and function, and we examined the genotype-phenotype correlation of [p.L206W]+[p.F508del] patients. We showed that p.L206W is a processing (class II) mutation since the CFTR biosynthetic pathway was severely impaired, whereas single-channel measurements indicated ion conductance similar to the wild-type protein. These data raise the larger question of the phenotypic variability of class II mutants, including p.F508del. Since multiple potential partners could modify the processing of the CFTR protein during its course to the cell surface, environmental and other genetic factors might contribute to this variability.

Adolescent↗
PubMed2004

Exploration of the basolateral chloride channels in the renal tubule using.

Chloride channels located on the basolateral membrane are known to be involved in chloride absorption in several parts of the renal tubule, and particularly in the thick ascending limb and distal convoluted tubule. The data available suggest that the ClC-K channels play the major role in this process. We provide here a description of the electrophysiological properties of these channels, still very incomplete at this stage, and we attempt to compare ClC-Ks to three chloride channels that we have identified in the basolateral membrane of microdissected fragments of the mouse renal tubule using the patch-clamp technique. Based on anion selectivity and dependence on external pH and calcium shown by the ClC-Ks, we propose candidate ClC-K1 and ClC-K2 in native tissue. We also discuss the possibility that chloride channels that do not belong to the ClC family may also be involved in the absorption of chloride across the cortical thick ascending limb.

Animals↗
PubMed2004

Vasopressin-stimulated CFTR Cl- currents are increased in the renal collecting duct cells of a mouse model of Liddle's syndrome.

Liddle's syndrome is a genetic form of hypertension linked to Na(+) retention caused by activating mutations in the COOH terminus of the beta or gamma subunit of the epithelial sodium channel (ENaC). In this study, we used the short-circuit current (I(sc)) method to investigate the effects of deamino-8-d-arginine vasopressin (dDAVP) on Na(+) and Cl(-) fluxes in primary cultures of cortical collecting ducts (CCDs) microdissected from the kidneys of mice with Liddle's syndrome carrying a stop codon mutation, corresponding to the beta-ENaC R(566) stop mutation (L) found in the original pedigree. Compared to wild-type (+/+) CCD cells, untreated L/+ and L/L CCD cells exhibited 2.7- and 4.2-fold increases, respectively, in amiloride-sensitive (Ams) I(sc), reflecting ENaC-dependent Na(+) absorption. Short-term incubation with dDAVP caused a rapid and significant increase (approximately 2-fold) in Ams I(sc) in +/+, but not in L/+ or L/L CCD cells. In sharp contrast, dDAVP induced a greater increase in 5-nitro-2-(3-phenylpropamino)benzoate (NPPB)-inhibited apical Cl(-) currents in amiloride-treated L/L and L/+ cells than in their +/+ counterparts. I(sc) recordings performed under apical ion substituted conditions revealed that the dDAVP-stimulated apical secretion of Cl(-), which was absent in cultured CCDs lacking CFTR, was 1.8-fold greater in L/+ and 3.7-fold greater in L/L CCD cells than in their +/+ CCD counterparts. After the basal membrane had been permeabilized with nystatin and a basal-to-apical Cl(-) gradient had been imposed, dDAVP also stimulated larger Cl(-) currents across L/L and L/+ CCD layers than +/+ CCD layers. These findings demonstrate that vasopressin stimulates greater apical CFTR Cl(-) conductance in the renal CCD cells of mice with Liddle's syndrome than in wild-type mice. This effect could contribute to the enhanced NaCl reabsorption observed in the distal nephron of patients with Liddle's syndrome.

Animals↗
PubMed2004

Heterogeneous distribution of chloride channels along the distal convoluted tubule probed by single-cell RT-PCR and patch clamp.

The distal convoluted tubule (DCT) is a heterogeneous segment subdivided into early (DCT1) and late (DCT2) parts, depending on the distribution of various transport systems. We do not have an exhaustive picture of the Cl(-) channels on the basolateral side: the presence of ClC-K2 channels is generally accepted, whereas that of ClC-K1 remains controversial. We used here single-cell RT-PCR and patch clamp to probe Cl(-) channel heterogeneity in microdissected mouse DCT at the molecular and functional levels. Our findings show that 63% of the DCT cells express ClC-K2 mRNA, either alone (type 1 cells: 47 and 23% in DCT1 and DCT2, respectively), or combined with ClC-K1, mostly in DCT2 (type 2 cells: 33%), but 37% of DCT1 and DCT2 cells do not express any ClC-K. Patch-clamp experiments revealed that a Cl(-) channel, with 9-pS conductance and Cl(-) > NO(3)(-) = Br(-) anion selectivity sequence, is present in the DCT1 and DCT2 basolateral membranes (87 and 71% of the patches, respectively). This dominant channel is likely to be ClC-K2 in type 1 cells. In type 2 cells, it could be ClC-K2 and/or ClC-K1 homodimers, but also ClC-K1/ClC-K2 heterodimers, or a mixture of all combinations. A second, distinct Cl(-) channel (13% of DCT1 patches, 29% of DCT2 patches) also displayed 9-pS conductance but had a completely different anion selectivity (I(-) > NO(3)(-) > Br(-) > Cl(-)), which was not compatible with that of the ClC-Ks. This indicates that a Cl(-) channel that is unlikely to belong to the ClC family may also be involved in Cl(-) absorption in the DCT2.

Absorption↗
PubMed2003

A chloride channel at the basolateral membrane of the distal-convoluted tubule: a candidate ClC-K channel.

The distal-convoluted tubule (DCT) of the kidney absorbs NaCl mainly via an Na+-Cl- cotransporter located at the apical membrane, and Na+, K+ ATPase at the basolateral side. Cl- transport across the basolateral membrane is thought to be conductive, but the corresponding channels have not yet been characterized. In the present study, we investigated Cl- channels on microdissected mouse DCTs using the patch-clamp technique. A channel of approximately 9 pS was found in 50% of cell-attached patches showing anionic selectivity. The NPo in cell-attached patches was not modified when tubules were preincubated in the presence of 10-5 M forskolin, but the channel was inhibited by phorbol ester (10-6 M). In addition, NPo was significantly elevated when the calcium in the pipette was increased from 0 to 5 mM (NPo increased threefold), or pH increased from 6.4 to 8.0 (NPo increased 15-fold). Selectivity experiments conducted on inside-out patches showed that the Na+ to Cl- relative permeability was 0.09, and the anion selectivity sequence Cl(-)--I(-) > Br(-)--NO3(-) > F(-). Intracellular NPPB (10-4 M) and DPC (10-3 M) blocked the channel by 65% and 80%, respectively. The channel was inhibited at acid intracellular pH, but intracellular ATP and PKA had no effect. ClC-K Cl- channels are characterized by their sensitivity to the external calcium and to pH. Since immunohistochemical data indicates that ClC-K2, and perhaps ClC-K1, are present on the DCT basolateral membrane, we suggest that the channel detected in this study may belong to this subfamily of the ClC channel family.

Animals↗
PubMed2002

Properties of an inwardly rectifying K(+) channel in the basolateral membrane of mouse TAL.

We investigated the properties of K(+) channels in the basolateral membrane of the cortical thick ascending limb (CTAL) using the patch-clamp technique. Approximately 34% of cell-attached patches contained an inwardly rectifying K(+) channel (K(+)-to-Na(+) permeability ratio approximately 22), having an inward conductance (G(in)) of 44 pS and an outward conductance (G(out)) of approximately 10 pS (G(in)/G(out) approximately 4). Channel activity (NP(o)) increased with depolarization. When the cytosolic sides of inside-out patches were exposed to an Mg(2+)-free medium, the channel had a G(in) of 50 pS and was weakly inwardly rectifying (G(in)/G(out) approximately 1). Cytosolic Mg(2+) reduced G(out), yielding a G(in)/G(out) of 3.8 at 1.3 mM Mg(2+). Internal Na(+) also yielded a G(in)/G(out) of 1.6 at 20 mM Na(+). Spermine reduced NP(o) on inside-out membrane patches. Sensitivity to spermine at depolarizing voltages [half-maximal inhibitory concentration (K(i)) = 0.2 microM] was much greater than at hyperpolarizing voltages (K(i) = 26 microM). Half-inactivation by 0.5 microM spermine occurred at a clamp potential of 43 mV, with an effective valence of 1.25. A sigmoid relationship between bath pH and NP(o) of inside-out membrane patches was observed, with a pK of 7.6 and a Hill coefficient of 1.8. Intracellular acidification also reduced the NP(o) of cell-attached patches. This channel is probably a major component of K(+) conductance in the CTAL basolateral membrane.

Adenosine Triphosphate↗
PubMed2001

Inhibition of the calcium release-activated calcium (CRAC) current in Jurkat T cells by the HIV-1 envelope protein gp160.

The HIV-1 envelope glycoprotein gp120/160 has pleiotropic effects on T cell function. We investigated whether Ca(2+) signaling, a crucial step for T cell activation, was altered by prolonged exposure of Jurkat T cells to gp160. Microfluorometric measurements showed that Jurkat cells incubated with gp160 had smaller (approximately 40%) increases in [Ca(2+)](i) in response to phytohemagglutinin and had a reduced Ca(2+) influx (approximately 25%). gp160 had similar effects on Jurkat cells challenged with thapsigargin. We used the patch clamp technique to record the Ca(2+) current, which is responsible for Ca(2+) influx and has properties of the calcium release-activated Ca(2+) current (I(CRAC)). gp160 reduced I(CRAC) by approximately 40%. The inhibitory effects of gp160 were antagonized by staurosporine (0.1 microm), an inhibitor of protein-tyrosine kinases and protein kinase Cs (PKCs), and by Gö 6976 (5 microm), an inhibitor acting especially on PKC alpha and PKC beta I. 12-O-Tetradecanoyl phorbol 13-acetate (16 nm), a PKC activator, reproduced the effects of gp160 in untreated cells. A Western blotting analysis of PKC isoforms alpha, beta I, delta, and zeta showed that only the cellular distribution of PKC alpha and -beta I were significantly modified by gp160. In addition, gp160 was able to modify the subcellular distribution of PKC alpha and PKC beta I caused by phytohemagglutinin. Therefore the reduction in I(CRAC) caused by prolonged incubation with gp160 is probably mediated by PKC alpha or -beta I.

Calcium↗