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TRPV4 channel is involved in the coupling of fluid viscosity changes to epithelial ciliary activity.

Andrade YN, Fernandes J, Vázquez E, Fernández-Fernández JM, Arniges M, Sánchez TM, Villalón M, Valverde MA - J. Cell Biol. (2005)

Bottom Line: This mechanical activation is prevented in native ciliated cells loaded with a TRPV4 antibody.Application of the TRPV4 synthetic ligand 4alpha-phorbol 12,13-didecanoate increased cationic currents, intracellular Ca(2+), and the CBF in the absence of a viscous load.Therefore, TRPV4 emerges as a candidate to participate in the coupling of fluid viscosity changes to the generation of the Ca(2+) signal required for the autoregulation of CBF.

View Article: PubMed Central - PubMed

Affiliation: Grup de Fisiologia Cellular i Molecular, Unitat de Senyalització Cellular, Universitat Pompeu Fabra, Barcelona 08003, Spain.

ABSTRACT
Autoregulation of the ciliary beat frequency (CBF) has been proposed as the mechanism used by epithelial ciliated cells to maintain the CBF and prevent the collapse of mucociliary transport under conditions of varying mucus viscosity. Despite the relevance of this regulatory response to the pathophysiology of airways and reproductive tract, the underlying cellular and molecular aspects remain unknown. Hamster oviductal ciliated cells express the transient receptor potential vanilloid 4 (TRPV4) channel, which is activated by increased viscous load involving a phospholipase A(2)-dependent pathway. TRPV4-transfected HeLa cells also increased their cationic currents in response to high viscous load. This mechanical activation is prevented in native ciliated cells loaded with a TRPV4 antibody. Application of the TRPV4 synthetic ligand 4alpha-phorbol 12,13-didecanoate increased cationic currents, intracellular Ca(2+), and the CBF in the absence of a viscous load. Therefore, TRPV4 emerges as a candidate to participate in the coupling of fluid viscosity changes to the generation of the Ca(2+) signal required for the autoregulation of CBF.

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Dextran-activated calcium entry pathway. (a) Cytosolic Ca2+ signal obtained in hamster oviductal ciliated cells exposed to 5 or 20% dextran and the effect of extracellular Ca2+ removal and 100 μM Gd3+ on the 20% dextran-induced Ca2+ signal. Traces are representative of five to six experiments under each condition. (b and c) Whole-cell cationic currents recorded in oviductal ciliated cells dialyzed with CsCl-containing pipette solution under control (1 cP) and 5% dextran (4.8 cP) (b) and 20% dextran solution alone (73 cP) or containing 100 μM Gd3+ (c). (d) Average current density measured at −100 mV and +100 mV under the following conditions: control (n = 27), 20% dextran (n = 15); 20% dextran + Gd3+ (n = 10); and 5% dextran (n = 11). *, P < 0.05, compared with control. (e) Oscillatory pattern of the cationic current obtained in a single cell exposed to 20% dextran.
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fig2: Dextran-activated calcium entry pathway. (a) Cytosolic Ca2+ signal obtained in hamster oviductal ciliated cells exposed to 5 or 20% dextran and the effect of extracellular Ca2+ removal and 100 μM Gd3+ on the 20% dextran-induced Ca2+ signal. Traces are representative of five to six experiments under each condition. (b and c) Whole-cell cationic currents recorded in oviductal ciliated cells dialyzed with CsCl-containing pipette solution under control (1 cP) and 5% dextran (4.8 cP) (b) and 20% dextran solution alone (73 cP) or containing 100 μM Gd3+ (c). (d) Average current density measured at −100 mV and +100 mV under the following conditions: control (n = 27), 20% dextran (n = 15); 20% dextran + Gd3+ (n = 10); and 5% dextran (n = 11). *, P < 0.05, compared with control. (e) Oscillatory pattern of the cationic current obtained in a single cell exposed to 20% dextran.

Mentions: To further investigate the relationship between mechanical stimulation and intracellular Ca2+, we monitored changes in cytosolic Ca2+ in response to low (5% dextran) and high (20% dextran) viscous loads, the latter triggering the CBF autoregulatory response. Fig. 2 a shows the ratiometric fura-2 fluorescence obtained in primary cultures of single oviductal ciliated cells. Exposure to 5% dextran solution did not modify the intracellular Ca2+ levels (Fig. 2 a), whereas 20% dextran solution (73 cP) triggered an oscillatory Ca2+ response in ciliated cells, which was prevented in the absence of extracellular Ca2+ or in the presence of 100 μM Gd3+. Interestingly, the Ca2+ oscillatory pattern emerged at the viscosity values that trigger the autoregulatory process (>30 cP; unpublished data).


TRPV4 channel is involved in the coupling of fluid viscosity changes to epithelial ciliary activity.

Andrade YN, Fernandes J, Vázquez E, Fernández-Fernández JM, Arniges M, Sánchez TM, Villalón M, Valverde MA - J. Cell Biol. (2005)

Dextran-activated calcium entry pathway. (a) Cytosolic Ca2+ signal obtained in hamster oviductal ciliated cells exposed to 5 or 20% dextran and the effect of extracellular Ca2+ removal and 100 μM Gd3+ on the 20% dextran-induced Ca2+ signal. Traces are representative of five to six experiments under each condition. (b and c) Whole-cell cationic currents recorded in oviductal ciliated cells dialyzed with CsCl-containing pipette solution under control (1 cP) and 5% dextran (4.8 cP) (b) and 20% dextran solution alone (73 cP) or containing 100 μM Gd3+ (c). (d) Average current density measured at −100 mV and +100 mV under the following conditions: control (n = 27), 20% dextran (n = 15); 20% dextran + Gd3+ (n = 10); and 5% dextran (n = 11). *, P < 0.05, compared with control. (e) Oscillatory pattern of the cationic current obtained in a single cell exposed to 20% dextran.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2171792&req=5

fig2: Dextran-activated calcium entry pathway. (a) Cytosolic Ca2+ signal obtained in hamster oviductal ciliated cells exposed to 5 or 20% dextran and the effect of extracellular Ca2+ removal and 100 μM Gd3+ on the 20% dextran-induced Ca2+ signal. Traces are representative of five to six experiments under each condition. (b and c) Whole-cell cationic currents recorded in oviductal ciliated cells dialyzed with CsCl-containing pipette solution under control (1 cP) and 5% dextran (4.8 cP) (b) and 20% dextran solution alone (73 cP) or containing 100 μM Gd3+ (c). (d) Average current density measured at −100 mV and +100 mV under the following conditions: control (n = 27), 20% dextran (n = 15); 20% dextran + Gd3+ (n = 10); and 5% dextran (n = 11). *, P < 0.05, compared with control. (e) Oscillatory pattern of the cationic current obtained in a single cell exposed to 20% dextran.
Mentions: To further investigate the relationship between mechanical stimulation and intracellular Ca2+, we monitored changes in cytosolic Ca2+ in response to low (5% dextran) and high (20% dextran) viscous loads, the latter triggering the CBF autoregulatory response. Fig. 2 a shows the ratiometric fura-2 fluorescence obtained in primary cultures of single oviductal ciliated cells. Exposure to 5% dextran solution did not modify the intracellular Ca2+ levels (Fig. 2 a), whereas 20% dextran solution (73 cP) triggered an oscillatory Ca2+ response in ciliated cells, which was prevented in the absence of extracellular Ca2+ or in the presence of 100 μM Gd3+. Interestingly, the Ca2+ oscillatory pattern emerged at the viscosity values that trigger the autoregulatory process (>30 cP; unpublished data).

Bottom Line: This mechanical activation is prevented in native ciliated cells loaded with a TRPV4 antibody.Application of the TRPV4 synthetic ligand 4alpha-phorbol 12,13-didecanoate increased cationic currents, intracellular Ca(2+), and the CBF in the absence of a viscous load.Therefore, TRPV4 emerges as a candidate to participate in the coupling of fluid viscosity changes to the generation of the Ca(2+) signal required for the autoregulation of CBF.

View Article: PubMed Central - PubMed

Affiliation: Grup de Fisiologia Cellular i Molecular, Unitat de Senyalització Cellular, Universitat Pompeu Fabra, Barcelona 08003, Spain.

ABSTRACT
Autoregulation of the ciliary beat frequency (CBF) has been proposed as the mechanism used by epithelial ciliated cells to maintain the CBF and prevent the collapse of mucociliary transport under conditions of varying mucus viscosity. Despite the relevance of this regulatory response to the pathophysiology of airways and reproductive tract, the underlying cellular and molecular aspects remain unknown. Hamster oviductal ciliated cells express the transient receptor potential vanilloid 4 (TRPV4) channel, which is activated by increased viscous load involving a phospholipase A(2)-dependent pathway. TRPV4-transfected HeLa cells also increased their cationic currents in response to high viscous load. This mechanical activation is prevented in native ciliated cells loaded with a TRPV4 antibody. Application of the TRPV4 synthetic ligand 4alpha-phorbol 12,13-didecanoate increased cationic currents, intracellular Ca(2+), and the CBF in the absence of a viscous load. Therefore, TRPV4 emerges as a candidate to participate in the coupling of fluid viscosity changes to the generation of the Ca(2+) signal required for the autoregulation of CBF.

Show MeSH
Related in: MedlinePlus