title: Dual Regulation of R-Type CaV2.3 Channels by M1 Muscarinic Receptors.
abstract: Voltage-gated Ca(2+) (CaV) channels are dynamically modulated by G protein-coupled receptors (GPCR). The M1 muscarinic receptor stimulation is known to enhance CaV2.3 channel gating through the activation of protein kinase C (PKC). Here, we found that M1 receptors also inhibit CaV2.3 currents when the channels are fully activated by PKC. In whole-cell configuration, the application of phorbol 12-myristate 13-acetate (PMA), a PKC activator, potentiated CaV2.3 currents by ∼two-fold. After the PMA-induced potentiation, stimulation of M1 receptors decreased the CaV2.3 currents by 52 ± 8%. We examined whether the depletion of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is responsible for the muscarinic suppression of CaV2.3 currents by using two methods: the Danio rerio voltage-sensing phosphatase (Dr-VSP) system and the rapamycin-induced translocatable pseudojanin (PJ) system. First, dephosphorylation of PI(4,5)P2 to phosphatidylinositol 4-phosphate (PI(4)P) by Dr-VSP significantly suppressed CaV2.3 currents, by 53 ± 3%. Next, dephosphorylation of both PI(4)P and PI(4,5)P2 to PI by PJ translocation further decreased the current by up to 66 ± 3%. The results suggest that CaV2.3 currents are modulated by the M1 receptor in a dual mode-that is, potentiation through the activation of PKC and suppression by the depletion of membrane PI(4,5)P2. Our results also suggest that there is rapid turnover between PI(4)P and PI(4,5)P2 in the plasma membrane.
authors.affiliation: Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea.
authors.forename: Jin-Young
authors.initials: JY
authors.lastname: Jeong
authors.affiliation: Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea.
authors.forename: Hae-Jin
authors.initials: HJ
authors.lastname: Kweon
authors.affiliation: Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea.
authors.forename: Byung-Chang
authors.initials: BC
authors.lastname: Suh
mesh_terms: D000818:Animals; D020908:Calcium Channels, R-Type / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry*; D005786:Gene Expression Regulation / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D018408:Patch-Clamp Techniques; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D043643:Receptor, Muscarinic M1 / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000378:metabolism
chemical_list: D020908:Calcium Channels, R-Type; D019269:Phosphatidylinositol 4,5-Diphosphate; D043643:Receptor, Muscarinic M1; D029961:Zebrafish Proteins; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate
keywords: CaV2.3 channel; Danio rerio voltage-sensitive phosphatase (Dr-VSP); M1 muscarinic receptor; PI(4,5)P2; Pseudojanin