title: The PDZ motif of the α1C subunit is not required for surface trafficking and adrenergic modulation of CaV1.2 channel in the heart.
abstract: Voltage-gated Ca(2+) channels play a key role in initiating muscle excitation-contraction coupling, neurotransmitter release, gene expression, and hormone secretion. The association of CaV1.2 with a supramolecular complex impacts trafficking, localization, turnover, and, most importantly, multifaceted regulation of its function in the heart. Several studies hint at an important role for the C terminus of the α1C subunit as a hub for multidimensional regulation of CaV1.2 channel trafficking and function. Recent studies have demonstrated an important role for the four-residue PDZ binding motif at the C terminus of α1C in interacting with scaffold proteins containing PDZ domains, in the subcellular localization of CaV1.2 in neurons, and in the efficient signaling to cAMP-response element-binding protein in neurons. However, the role of the α1C PDZ ligand domain in the heart is not known. To determine whether the α1C PDZ motif is critical for CaV1.2 trafficking and function in cardiomyocytes, we generated transgenic mice with inducible expression of an N-terminal FLAG epitope-tagged dihydropyridine-resistant α1C with the PDZ motif deleted (ΔPDZ). These mice were crossed with α-myosin heavy chain reverse transcriptional transactivator transgenic mice, and the double-transgenic mice were fed doxycycline. The ΔPDZ channels expressed, trafficked to the membrane, and supported robust excitation-contraction coupling in the presence of nisoldipine, a dihydropyridine Ca(2+) channel blocker, providing functional evidence that they appropriately target to dyads. The ΔPDZ Ca(2+) channels were appropriately regulated by isoproterenol and forskolin. These data indicate that the α1C PDZ motif is not required for surface trafficking, localization to the dyad, or adrenergic stimulation of CaV1.2 in adult cardiomyocytes.
authors.affiliation: From the Division of Cardiology, Departments of Medicine and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032 and.
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.affiliation: From the Division of Cardiology, Departments of Medicine and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032 and.
authors.forename: Alexander
authors.initials: A
authors.lastname: Katchman
authors.affiliation: From the Division of Cardiology, Departments of Medicine and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032 and.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Weinberg
authors.affiliation: From the Division of Cardiology, Departments of Medicine and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032 and.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Abrams
authors.affiliation: From the Division of Cardiology, Departments of Medicine and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032 and.
authors.forename: Tahmina
authors.initials: T
authors.lastname: Samad
authors.affiliation: From the Division of Cardiology, Departments of Medicine and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032 and.
authors.forename: Elaine
authors.initials: E
authors.lastname: Wan
authors.affiliation: the Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.
authors.forename: Geoffrey S
authors.initials: GS
authors.lastname: Pitt
authors.affiliation: From the Division of Cardiology, Departments of Medicine and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032 and sm460@columbia.edu.
authors.forename: Steven O
authors.initials: SO
authors.lastname: Marx
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D002121:Calcium Channel Blockers / Q000737:chemistry; D020746:Calcium Channels, L-Type / Q000737:chemistry* / Q000502:physiology*; D005576:Colforsin / Q000737:chemistry; D000939:Epitopes / Q000737:chemistry; D017353:Gene Deletion; D006321:Heart / Q000502:physiology*; D006801:Humans; D008024:Ligands; D051379:Mice; D008822:Mice, Transgenic; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D015737:Nisoldipine / Q000737:chemistry; D017434:Protein Structure, Tertiary; D011817:Rabbits; D013499:Surface Properties
chemical_list: C514350:CACNA1C protein, mouse; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D000939:Epitopes; D008024:Ligands; D005576:Colforsin; D015737:Nisoldipine
keywords: Adrenergic Stimulation; Calcium Channel; Electrophysiology; Heart; PDZ Domain; Transgenic Mice