title: The inhibitory effect of Gβγ and Gβ isoform specificity on ENaC activity.
abstract: Epithelial Na(+) channel (ENaC) activity, which determines the rate of renal Na(+) reabsorption, can be regulated by G protein-coupled receptors. Regulation of ENaC by Gα-mediated downstream effectors has been studied extensively, but the effect of Gβγ dimers on ENaC is unclear. A6 cells endogenously contain high levels of Gβ1 but low levels of Gβ3, Gβ4, and Gβ5 were detected by Q-PCR. We tested Gγ2 combined individually with Gβ1 through Gβ5 expressed in A6 cells, after which we recorded single-channel ENaC activity. Among the five β and γ2 combinations, β1γ2 strongly inhibits ENaC activity by reducing both ENaC channel number (N) and open probability (Po) compared with control cells. In contrast, the other four β-isoforms combined with γ2 have no significant effect on ENaC activity. By using various inhibitors to probe Gβ1γ2 effects on ENaC regulation, we found that Gβ1γ2-mediated ENaC inhibition involved activation of phospholipase C-β and its enzymatic products that induce protein kinase C and ERK1/2 signaling pathways.
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural Univ., Nanjing 210095, China. lyu@njau.edu.cn.
authors.forename: Ling
authors.initials: L
authors.lastname: Yu
authors.forename: Otor
authors.initials: O
authors.lastname: Al-Khalili
authors.forename: Billie Jeanne
authors.initials: BJ
authors.lastname: Duke
authors.forename: James D
authors.initials: JD
authors.lastname: Stockand
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Eaton
authors.forename: Hui-Fang
authors.initials: HF
authors.lastname: Bao
mesh_terms: D000818:Animals; D002460:Cell Line; D053503:Epithelial Sodium Channels / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D044387:GTP-Binding Protein beta Subunits / Q000502:physiology*; D044388:GTP-Binding Protein gamma Subunits / Q000502:physiology*; D015640:Ion Channel Gating / Q000502:physiology; D007668:Kidney / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D054801:Phosphoinositide Phospholipase C / Q000378:metabolism; D020033:Protein Isoforms / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D012964:Sodium / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D053503:Epithelial Sodium Channels; C118981:G-protein Beta gamma; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D020033:Protein Isoforms; D012964:Sodium; D048049:Extracellular Signal-Regulated MAP Kinases; D054801:Phosphoinositide Phospholipase C
keywords: ENaC; G protein βγ subunits; phospholipase C; protein kinase C; single channels