Regulation of T-type calcium channels by Rho-associated kinase

Abstract

We investigated the regulation of T-type channels by Rho-associated kinase (ROCK). Activation of ROCK via the endogenous ligand lysophosphatidic acid (LPA) reversibly inhibited the peak current amplitudes of rat Ca(v)3.1 and Ca(v)3.3 channels without affecting the voltage dependence of activation or inactivation, whereas Ca(v)3.2 currents showed depolarizing shifts in these parameters. LPA-induced inhibition of Ca(v)3.1 was dependent on intracellular GTP, and was antagonized by treatment with ROCK and RhoA inhibitors, LPA receptor antagonists or GDPssS. Site-directed mutagenesis of the Ca(v)3.1 alpha1 subunit revealed that the ROCK-mediated effects involve two distinct phosphorylation consensus sites in the domain II-III linker. ROCK activation by LPA reduced native T-type currents in Y79 retinoblastoma and in lateral habenular neurons, and upregulated native Ca(v)3.2 current in dorsal root ganglion neurons. Our data suggest that ROCK is an important regulator of T-type calcium channels, with potentially far-reaching implications for multiple cell functions modulated by LPA.

Effects of familial hemiplegic migraine type 1 mutation T666M on voltage-gated calcium channel activities in trigeminal ganglion neurons

“…First, we minimized HVA VGCC currents with a cocktail of type-specific blockers, including 10 M nifedipine, 2 M -CTx-GVIA, 0.5 M -Aga-IVA, and 0.2 M SNX482 for a subset of R-type current (Fang et al 2007;Iftinca et al 2007). Next, we recorded Ba 2ϩ currents by depolarizing neurons to Ϫ40 mV from either Ϫ60 or Ϫ110 mV V h (Fig.…”

Protein Kinase C-Mediated Inhibition of Recombinant T-Type CaV3.2 Channels by Neurokinin 1 Receptors

“…It has been shown previously that T-type Ca V 3.2 channels are modulated by several different types of heterotrimeric G protein-coupled receptors (Welsby et al, 2003;Wolfe et al, 2003;Kim et al, 2006Kim et al, , 2007Iftinca et al, 2007;Tao et al, 2008). However, little is currently known regarding the modulation of T-type channels by tachykinin receptors.…”

Endogenous Rho-Kinase Signaling Maintains Synaptic Strength by Stabilizing the Size of the Readily Releasable Pool of Synaptic Vesicles

“…However, whether ROCK regulates neuronal physiology by modulating intrinsic membrane properties and/or afferent input drive to neurons remains unknown so far. In this way, ROCK regulates several ionic channels (Li et al, 2002;Piccoli et al, 2004;Staruschenko et al, 2004;Iftinca et al, 2007).…”

“…This could be explained by lack of regulation of the intrinsic HMN excitability by this isoform, and/or by endogenous activity of motoneuronal ROCK␣ below the level required to reveal its impact on membrane properties in our experimental conditions. The former possibility is less likely because RhoA/ROCK system modulates the activity of several classes of ion channels (Cachero et al, 1998;Li et al, 2002;Storey et al, 2002;Staruschenko et al, 2004;Iftinca et al, 2007), some of which are present in motoneurons. These findings rule out the possibility that in our experimental preparation the functional alterations induced by ROCK inhibition were contaminated by changes in intrinsic membrane properties of HMNs.…”