Calcium Entry Stimulated by Swelling of Madin-Darby Canine Kidney Cells

Wöll, Ewald; Ritter, Markus; Haller, Thomas; Völkl, Harald; Läng, Florian

doi:10.1159/000189295

Cited by 11 publications

(1 citation statement)

References 21 publications

(28 reference statements)

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“…Subsequently, activation of the Cl – efflux pathway occurs, with a delay with respect to the onset of K + efflux [88, 90, 91, 92, 93, 94]. In contrast to epithelial cells, in cells exhibiting Ca 2+ -independent osmosensitive K + channels and RVD, the primary event after swelling is the immediate activation of the Cl – exit pathway and the consequent depolarization [59].…”

Section: Ca2+ and Osmolyte Efflux Pathwaysmentioning

confidence: 99%

Influence of Calcium on Regulatory Volume Decrease: Role of Potassium Channels

Pasantes‐Morales¹,

Mulia²

2000

Nephron

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In most cell types, hyposmotic swelling consistently elicits an increase in the concentration of cytosolic Ca²⁺ – [Ca²⁺]_i – with contributions of extracellular and intracellular sources. The mechanisms of Ca²⁺ entry and release from endogenous sources are not fully clarified and may be cell specific. The ubiquity of the swelling-evoked [Ca²⁺]_i rise makes Ca²⁺ a likely candidate for a role as osmotransducing signal. However, the regulatory volume decrease (RVD) which follows swelling and the osmolyte fluxes involved in this process are not always Ca²⁺ dependent. It was found that, with a few exceptions, in most cell types the osmosensitive Cl^– efflux pathway and the swelling-activated organic osmolyte fluxes are Ca²⁺ independent. In contrast, Ca²⁺-dependent or Ca²⁺-independent K⁺ fluxes activated by swelling are detected, depending on the cell type. The close correlation found in this review between the Ca²⁺ dependence of RVD and that of the K⁺ channels activated by swelling led to the conclusion that it is the type of osmosensitive K⁺ pathway which largely confers the Ca²⁺ dependence to RVD. Interestingly, this coincidence of Ca²⁺-dependent K⁺ efflux and RVD is found predominantly in epithelial cells, whereas in nonepithelial cells both processes are largely Ca²⁺ independent. In these cells, the [Ca²⁺]_i rise elicited by swelling may be an epiphenomenon.

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Section: Ca2+ and Osmolyte Efflux Pathwaysmentioning

confidence: 99%

Influence of Calcium on Regulatory Volume Decrease: Role of Potassium Channels

Pasantes‐Morales¹,

Mulia²

2000

Nephron

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Migration of transformed renal epithelial cells is regulated by K + channel modulation of actin cytoskeleton and cell volume

Schwab¹,

Schuricht²,

Seeger³

et al. 1999

Pfl�gers Archiv European Journal of Physiology

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Migration of transformed renal epithelial (MDCK-F) cells depends on the polarized activity of a Ca2+-sensitive K+ channel (IK channel; Pflügers Arch 432:R87-R93, 1996). This study was aimed at elucidating the functional link between the IK channel and the actin cytoskeleton which is required for cell locomotion. We monitored migration of MDCK-F cells with video microscopy, quantified filamentous actin with phalloidin binding, and measured the intracellular Ca2+ concentration ([Ca2+]i) with the fluorescent dye fura-2/AM. We compared the effects of IK channel activation or inhibition with those of hypotonic swelling or hypertonic shrinkage. IK channel inhibition with charybdotoxin (CTX) or cell swelling (omission of up to 50 mmol/l NaCl) as well as IK channel activation with 1-ethyl-2-benzimidazolinone (1-EBIO) or cell shrinkage (addition of up to 100 mmol/l mannitol) reduce the rate of migration dose-dependently by up to 80%, i.e., to the same extent as cytochalasin D. Inhibition of migration is accompanied either by actin depolymerization (CTX and cell swelling) or by actin polymerization (1-EBIO and cell shrinkage). Changes of migration and phalloidin binding induced by CTX and cell swelling or by 1-EBIO and cell shrinkage, respectively, are linearly correlated with each other. CTX and cell swelling elicit a rise of [Ca2+]i whereas 1-EBIO and cell shrinkage induce a slight decrease of [Ca2+]i in most MDCK-F cells. Taken together IK-channel-dependent perturbations of cell volume and anisotonicity elicit virtually identical effects on migration, actin filaments and [Ca2+]i. We therefore suggest that cell volume - possibly via [Ca2+]i - is the link between IK channel activity, actin filaments and migration. We propose a model for how temporal and local changes of cell volume can support the migration of MDCK-F cells.

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Temperature-modulated Diversity of TRPV4 Channel Gating

Gao

O’Neil

2003

Journal of Biological Chemistry

279

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The TRPV4 calcium-permeable channel was cloned from mouse kidney M-1 cells, and the effect of temperature modulation on channel gating/activation by physical and chemical signals was evaluated. A TRPV4 cDNA construct with a C-terminal V5 epitope was stably transfected into human embryonic kidney (HEK) 293 and Chinese hamster ovary cells resulting in high levels of expression at the plasma membrane. Channel activation was assessed from changes in calcium influx (fura-2 fluorescence measurements) or whole cell currents (patch clamp analysis). At room temperature (22-24°C), exposure of TRPV4-transfected cells to hypotonic medium (225 mOsm/liter) or a non-protein kinase C (PKC)-activating phorbol ester derivative, 4␣-phorbol 12,13-decanoate (100 nM), induces modest channel activation, whereas phorbol 12-myristate 13-acetate (100 nM), a PKC-activating phorbol ester, and shear stress (3-20 dyne/cm 2 ) had minimal or no effect on channel activation. In contrast, at elevated temperatures (37°C) the channel was rapidly activated by all stimuli. Inhibition of PKC by calphostin C (50 nM) or staurosporine (500 nM) abolished phorbol 12-myristate 13-acetate-induced activation of the channel without affecting the response to other stimuli. Ruthenium red (1 M) effectively blocked the channel activity by all stimuli. It is concluded that temperature is a critical modulator of TRPV4 channel gating, leading to activation of the channel by a diverse range of microenvironmental chemical and physical signals utilizing a least two transduction pathways, one PKC-dependent and one PKC-independent. The convergence of multiple signals and transduction pathways on the same channel indicate that the channel functions as a molecular integrator of microenvironmental chemical and physical signals.The TRP calcium-permeable cation channels are a rapidly growing superfamily of channels expressed in a broad range of both excitable and nonexcitable cells. The channels, in general, are not voltage-activated but appear to be activated by a broad range of ligands and intracellular mediators (1-7). The superfamily has been divided into three main subfamilies based on structural and functional similarities: TPRVC, the canonical TRP channels first identified in Drosophila; TRPV, the vanilloid subfamily named after its first member, the vanilloid receptor (or capsaicin receptor; renamed TRPV1); and TRPM, the melatonin subfamily named after its first member, melatonin (see Refs. 1 and 8 for nomenclature). The TRPV subfamily has demonstrated a notable broad sensitivity to chemical and physical stimuli, particularly for TRPV1, which is activated by various noxious mediators, including heat, acid, and capsaicin (the hot ingredient of peppers), and by endogenous lipid mediators, such as diacylglycerol and anandamide (2, 5, 9). Other members of the TRPV subfamily have been shown, so far, to have a narrower range of sensitivities: heat and insulinlike growth factor-I for TRPV2 (10, 11); heat for TRPV3 (12)(13)(14); and vitamin D and related ligands for TRPV5 (4)...

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Calcium Entry Stimulated by Swelling of Madin-Darby Canine Kidney Cells

Cited by 11 publications

References 21 publications

Influence of Calcium on Regulatory Volume Decrease: Role of Potassium Channels

Influence of Calcium on Regulatory Volume Decrease: Role of Potassium Channels

Migration of transformed renal epithelial cells is regulated by K + channel modulation of actin cytoskeleton and cell volume

Temperature-modulated Diversity of TRPV4 Channel Gating

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