title: L-type Ca2+ channel facilitation mediated by phosphorylation of the beta subunit by CaMKII.
abstract: L-type Ca(2+) channels (LTCCs) are major entry points for Ca(2+) in many cells. Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is associated with cardiac LTCC complexes and increases channel open probability (P(O)) to dynamically increase Ca(2+) current (I(Ca)) and augment cellular Ca(2+) signaling by a process called facilitation. However, the critical molecular mechanisms for CaMKII localization to LTCCs and I(Ca) facilitation in cardiomyocytes have not been defined. We show CaMKII binds to the LTCC beta(2a) subunit and preferentially phosphorylates Thr498 in beta(2a). Mutation of Thr498 to Ala (T498A) in beta(2a) prevents CaMKII-mediated increases in the P(O) of recombinant LTCCs. Moreover, expression of beta(2a)(T498A) in adult cardiomyocytes ablates CaMKII-mediated I(Ca) facilitation, demonstrating that phosphorylation of beta(2a) at Thr498 modulates native calcium channels. These findings reveal a molecular mechanism for targeting CaMKII to LTCCs and facilitating I(Ca) that may modulate Ca(2+) entry in diverse cell types coexpressing CaMKII and the beta(2a) subunit.
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
authors.forename: Chad E
authors.initials: CE
authors.lastname: Grueter
authors.forename: Sunday A
authors.initials: SA
authors.lastname: Abiria
authors.forename: Igor
authors.initials: I
authors.lastname: Dzhura
authors.forename: Yuejin
authors.initials: Y
authors.lastname: Wu
authors.forename: Amy-Joan L
authors.initials: AJ
authors.lastname: Ham
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Mohler
authors.forename: Mark E
authors.initials: ME
authors.lastname: Anderson
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Colbran
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020746:Calcium Channels, L-Type / Q000737:chemistry / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D006801:Humans; D015640:Ion Channel Gating; D051379:Mice; D008969:Molecular Sequence Data; D032383:Myocytes, Cardiac / Q000166:cytology; D010766:Phosphorylation; D010769:Phosphothreonine / Q000378:metabolism; D011485:Protein Binding; D021122:Protein Subunits; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: C491527:Cacnb2 protein, rat; D020746:Calcium Channels, L-Type; D021122:Protein Subunits; D011994:Recombinant Proteins; D010769:Phosphothreonine; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases