title: In vivo expression of G-protein beta1gamma2 dimer in adult mouse skeletal muscle alters L-type calcium current and excitation-contraction coupling.
abstract: A number of G-protein-coupled receptors are expressed in skeletal muscle but their roles in muscle physiology and downstream effector systems remain poorly investigated. Here we explored the functional importance of the G-protein betagamma (Gbetagamma) signalling pathway on voltage-controlled Ca(2+) homeostasis in single isolated adult skeletal muscle fibres. A GFP-tagged Gbeta(1)gamma(2) dimer was expressed in vivo in mice muscle fibres. The GFP fluorescence pattern was consistent with a Gbeta(1)gamma(2) dimer localization in the transverse-tubule membrane. Membrane current and indo-1 fluorescence measurements performed under voltage-clamp conditions reveal a drastic reduction of both L-type Ca(2+) current density and of peak amplitude of the voltage-activated Ca(2+) transient in Gbeta(1)gamma(2)-expressing fibres. These effects were not observed upon expression of Gbeta(2)gamma(2), Gbeta(3)gamma(2) or Gbeta(4)gamma(2). Our data suggest that the G-protein beta(1)gamma(2) dimer may play an important regulatory role in skeletal muscle excitation-contraction coupling.
authors.affiliation: Université Lyon 1, UMR CNRS 5123, Physiologie Intégrative Cellulaire et Moléculaire, Bâtiment R. Dubois, 43 boulevard du 11 novembre 1918, Villeurbanne, France. norbert.weiss@yahoo.fr
authors.forename: Norbert
authors.initials: N
authors.lastname: Weiss
authors.forename: Claude
authors.initials: C
authors.lastname: Legrand
authors.forename: Sandrine
authors.initials: S
authors.lastname: Pouvreau
authors.forename: Hicham
authors.initials: H
authors.lastname: Bichraoui
authors.forename: Bruno
authors.initials: B
authors.lastname: Allard
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Zamponi
authors.forename: Michel
authors.initials: M
authors.lastname: De Waard
authors.forename: Vincent
authors.initials: V
authors.lastname: Jacquemond
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000502:physiology*; D002478:Cells, Cultured; D019281:Dimerization; D044387:GTP-Binding Protein beta Subunits / Q000378:metabolism*; D015870:Gene Expression / Q000502:physiology; D015640:Ion Channel Gating / Q000502:physiology*; D051379:Mice; D009119:Muscle Contraction / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000502:physiology*
chemical_list: D020746:Calcium Channels, L-Type; D044387:GTP-Binding Protein beta Subunits; D002118:Calcium