Decoy calcium channel beta subunits modulate contractile function in myocytes

Fan, Qigao; Vanderpool, Kathleen M.; O’Connor, Jessica; Marsh, James D.

doi:10.1007/978-1-4757-4712-6_1

Cited by 2 publications

(4 citation statements)

References 29 publications

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“…Second, mutated β subunits have been designed that co-assemble with the α 1C subunit in the endoplasmic reticulum but prevent its translocation to the plasma membrane. In cardiac cells, these agents reduce the excitation-contraction coupling that relies on Ca 2+ entry through Ca L channels, but do not disrupt the kinetics of contraction or relaxation (Fan et al, 2003). Exciting findings such as these indicate that the development of new classes of antihypertensive drugs will rely on identifying the subunit basis of Ca L channels in the vasculature, and designing drugs to reduce their expression or activity.…”

Section: Implications For Antihypertensive Therapiesmentioning

confidence: 99%

“…A disruption of this process is thought to reduce Ca L channel formation in some forms of heart failure, resulting in a decline in Ca 2+ entry and cell contractility (Fan et al, 2003). Trafficking of α 1C also can be affected by PI3K and Akt/PKB in a β 2 subunit-dependent fashion (Viard et al, 2004), and by the interaction of β subunits with Rem and Rad GTPases (Beguin et al, 2001;Finlin et al, 2003).…”

Section: How Does High Blood Pressure Induce Ca L Channel Expression?mentioning

confidence: 99%

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Vascular calcium channels and high blood pressure: Pathophysiology and therapeutic implications

Sonkusare

Palade

Marsh

et al. 2006

Vascular Pharmacology

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Long-lasting Ca 2+ (Ca L ) channels of the Ca v 1.2 gene family are heteromultimeric structures that are minimally composed of a pore-forming α 1C subunit and regulatory β and α 2 δ subunits in vascular smooth muscle cells. The Ca L channels are the primary pathways for voltage-gated Ca 2+ influx that trigger excitation-contraction coupling in small resistance vessels. Notably, vascular smooth muscle cells of hypertensive rats show an increased expression of Ca L channel α 1C subunits, which is associated with elevated Ca 2+ influx and the development of abnormal arterial tone. Indeed, blood pressure per se appears to promote Ca L channel expression in small arteries, and even short-term rises in pressure may alter channel expression. Membrane depolarization has been shown to be one stimulus associated with elevated blood pressure that promotes Ca L channel expression at the plasma membrane. Future studies to define the molecular processes that regulate Ca L channel expression in vascular smooth muscle cells will provide a rational basis for designing antihypertensive therapies to normalize Ca L channel expression and the development of anomalous vascular tone in hypertensive pathologies.

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Section: Implications For Antihypertensive Therapiesmentioning

confidence: 99%

Section: How Does High Blood Pressure Induce Ca L Channel Expression?mentioning

confidence: 99%

Vascular calcium channels and high blood pressure: Pathophysiology and therapeutic implications

Sonkusare

Palade

Marsh

et al. 2006

Vascular Pharmacology

Self Cite

122

115

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show abstract

“…The optimal dose of crude viral stock (multiplicity of infection, 50 -100) needed to optimize protein expression without visible cell death was determined by fluorescent imaging and immunoblot techniques. Experimental conditions were developed that produced Ͼ95% infection of HL-1 cells for each of the constructs studied, as described previously (Fan et al, 2003;Telemaque-Potts et al, 2003;Chen et al, 2005). All studies on HL-1 cells were performed between 24 and 48 h after transfection.…”

Section: Methodsmentioning

confidence: 99%

“…Then, it was linearized and cotransformed into Escherichia coli BJ5183 cells with pAdEasy-1, the adenoviral backbone. A CMV-GFP lacking any ␤ subunit construct also was subcloned into a pShuttle vector to construct a control virus (Fan et al, 2003). Recombinants were then linearized and transfected into human embryonic kidney (HEK) 293 cells (American Type Culture Collection, Manassas, VA) using FuGENE 6 reagent (Roche Molecular Systems, Alameda, CA).…”

Section: Methodsmentioning

confidence: 99%

Design of Mutant β₂Subunits as Decoy Molecules to Reduce the Expression of Functional Ca²⁺Channels in Cardiac Cells

Télémaque

Sonkusare²,

Grain³

et al. 2008

J Pharmacol Exp Ther

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Calcium influx through long-lasting ("L-type") Ca 2ϩ channels (Ca V ) drives excitation-contraction in the normal heart. Dysregulation of this process contributes to Ca 2ϩ overload, and interventions that reduce expression of the pore-forming ␣ 1 subunit may alleviate cytosolic Ca 2ϩ excess. As a molecular approach to disrupt the assembly of Ca V 1.2 (␣ 1C ) channels at the cell membrane, we targeted the Ca 2ϩ channel ␤ 2 subunit, an intracellular chaperone that interacts with ␣ 1C via its ␤ interaction domain (BID) to promote Ca V 1.2 channel expression. Recombinant adenovirus expressing either the full ␤ 2 subunit (Full-␤ 2 ) or truncated ␤ 2 subunit constructs lacking either the C terminus, N terminus, or both (N-BID, C-BID, and BID, respectively) fused to green fluorescent protein were developed as potential decoys and overexpressed in HL-1 cells. Fluorescence microscopy revealed that the localization of Full-␤ 2 at the surface membrane was associated with increased Ca 2ϩ current mainly attributed to Ca V 1.2 channels. In contrast, truncated N-BID and C-BID constructs showed punctate intracellular expression, and BID showed a diffuse cytosolic distribution. Total expression of the ␣ 1C protein of Ca V 1.2 channels was similar between groups, but HL-1 cells overexpressing C-BID and BID exhibited reduced Ca 2ϩ current. C-BID and BID also attenuated Ca 2ϩ current associated with another L-type Ca 2ϩ channel, Ca V 1.3, but they did not reduce transient Ca 2ϩ currents attributed to Ca V 3 channels. These results suggest that ␤ 2 subunit mutants lacking the N terminus may preferentially disrupt the proper localization of L-type Ca 2ϩ channels in the cell membrane. Cardiac-specific delivery of these decoy molecules in vivo may represent a gene-based treatment for pathologies involving Ca 2ϩ overload.The predominant voltage-gated Ca 2ϩ channels (Ca V ) in cardiac cells are the dihydropyridine-sensitive Ca V 1.2 (␣ 1C ) channels that mediate long-lasting ("L-type") Ca 2ϩ current as a critical step in excitation-contraction coupling (Bers, 2002). The Ca V 1.2 channels are multiprotein complexes composed of a large, pore-forming ␣ 1C subunit and accessory ␤ and ␣ 2 -␦ subunits. The expression level of functional Ca V 1.2 channels is regulated by the ␤ subunits (␤ 1 , ␤ 2 , ␤ 3 , and ␤ 4 ), which are cytoplasmic proteins encoded by four different genes, including multiple splice variants (Foell et al., 2004). The ␤ 2 subunit is predominantly expressed in rat ventricular myocytes, although other gene families have been reported. It is noteworthy that ␤ 2 acts as a molecular chaperone that escorts ␣ 1C to the sarcolemma to localize functional Ca V 1.2 channels at the surface membrane De Waard et al., 1996;Opatowsky et al., 2003). Indeed, we recently reported that overexpression of ␤ 2 in isolated feline ventricular myocytes significantly increases Ca 2ϩ influx and cardiac contractility (Chen et al., 2005). Although mutations This work was supported in part by the

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Decoy calcium channel beta subunits modulate contractile function in myocytes

Cited by 2 publications

References 29 publications

Vascular calcium channels and high blood pressure: Pathophysiology and therapeutic implications

Vascular calcium channels and high blood pressure: Pathophysiology and therapeutic implications

Design of Mutant β₂Subunits as Decoy Molecules to Reduce the Expression of Functional Ca²⁺Channels in Cardiac Cells

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Decoy calcium channel beta subunits modulate contractile function in myocytes

Cited by 2 publications

References 29 publications

Vascular calcium channels and high blood pressure: Pathophysiology and therapeutic implications

Vascular calcium channels and high blood pressure: Pathophysiology and therapeutic implications

Design of Mutant β2Subunits as Decoy Molecules to Reduce the Expression of Functional Ca2+Channels in Cardiac Cells

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Design of Mutant β₂Subunits as Decoy Molecules to Reduce the Expression of Functional Ca²⁺Channels in Cardiac Cells