C-terminal Fragments of the α1C(CaV1.2) Subunit Associate with and Regulate L-type Calcium Channels Containing C-terminal-truncated α1CSubunits

Gao, Tianyan; Cuadra, Adolfo E.; Ma, Hong; Bünemann, Moritz; Gerhardstein, Brian L.; Cheng, Tong; Eick, Robert Ten; Hosey, M. Marlene

doi:10.1074/jbc.m008000200

Cited by 114 publications

(111 citation statements)

References 23 publications

(28 reference statements)

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“…3d, lane 2). The multiple bands in the positive control have been reported previously (26, 34 -36) and have been demonstrated to arise from post-translational proteolysis of the full-length protein (36). Our data show that while Jurkat T lymphocytes express a small amount of full-length ␣ 1 1.2 protein, the predominant form expressed is a truncated 119 kDa protein.…”

Section: L-type Ca 2ϩ Channel Antagonists Partially Inhibit Thapsigarsupporting

confidence: 83%

Non-voltage-gated L-type Ca2+ Channels in Human T Cells

Stokes¹,

Gordon²,

Grafton

2004

Journal of Biological Chemistry

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In T lymphocytes, engagement of the antigen receptor leads to a biphasic Ca 2؉ flux consisting of a mobilization of Ca 2؉ from intracellular stores followed by a lower but sustained elevation that is dependent on extracellular Ca 2؉ . The prolonged Ca 2؉ flux is required for activation of transcription factors and for subsequent activation of the T cell. Ca 2؉ influx requires as yet unidentified Ca 2؉ channels, which potentially play a role in T cell activation. Here we present evidence that human T cells express a non-voltage-gated Ca 2؉ channel related to L-type voltage-gated Ca 2؉ channels. Drugs that block classical L-type channels inhibited the initial phase of the antigen receptor-induced Ca 2؉ flux and could also inhibit the sustained phase of the Ca 2؉ signal suggesting a role for the L-type Ca 2؉ channel in antigen receptor signaling. T cells expressed transcripts for the ␣ 1 1.2 and ␣ 1 1.3 pore-forming subunits of L-type voltage-gated Ca 2؉ channels and transcripts for all four known ␤-subunits including several potential new splice variants. Jurkat T leukemia cells expressed a small amount of full-length ␣ 1 1.2 protein but the dominant form was a truncated protein identical in size to a truncated ␣ 1 1.2 protein known to be expressed in B lymphocytes. They further expressed a truncated form of the ␣ 1 1.3 subunit and auxiliary ␤1-and ␤3-subunit proteins. Our data strongly suggest that functional but non-voltage-gated L-type Ca 2؉ channels are expressed at the plasma membrane in T cells and play a role in the antigen receptor-mediated Ca 2؉ flux in these cells.

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Section: L-type Ca 2ϩ Channel Antagonists Partially Inhibit Thapsigarsupporting

confidence: 83%

Non-voltage-gated L-type Ca2+ Channels in Human T Cells

Stokes¹,

Gordon²,

Grafton

2004

Journal of Biological Chemistry

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“…The Distal C-terminal Domain Is Required for Normal Functional Expression of Ca V 1.2 Channels in Neurons in Vivo-Cterminal truncation of the Ca V 1.2 channel results in a 4 -6-fold higher calcium channel activity than the full-length form in heterologous expression systems (42,43), and the co-expressed distal C terminus is a potent inhibitor of channel activity (42,50). These studies imply that the C terminus exerts an inhibitory effect on calcium current, but these effects of C-terminal truncation have not been determined in vivo.…”

Section: Discussionmentioning

confidence: 99%

Functional Roles of a C-terminal Signaling Complex of CaV1 Channels and A-kinase Anchoring Protein 15 in Brain Neurons

Marshall

Clark

Westenbroek

et al. 2011

Journal of Biological Chemistry

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Regulation of Ca V 1.2 channels in cardiac myocytes by the ␤-adrenergic pathway requires a signaling complex in which the proteolytically processed distal C-terminal domain acts as an autoinhibitor of channel activity and mediates up-regulation by the ␤-adrenergic receptor and PKA bound to A-kinase anchoring protein 15 (AKAP15). We examined the significance of this distal C-terminal signaling complex for Ca V 1.2 and Ca V 1.3 channels in neurons. AKAP15 co-immunoprecipitates with Ca V 1.2 and Ca V 1.3 channels. AKAP15 has overlapping localization with Ca V 1.2 and Ca V 1.3 channels in cell bodies and proximal dendrites and is closely co-localized with Ca V 1.2 channels in punctate clusters. The neuronal AKAP MAP2B, which also interacts with Ca V 1.2 and Ca V 1.3 channels, has complementary localization to AKAP15, suggesting different functional roles in calcium channel regulation. Studies with mice that lack the distal C-terminal domain of Ca V 1.2 channels (Ca V 1.2⌬DCT) reveal that AKAP15 interacts with neuronal Ca V 1.2 channels via their C terminus in vivo and is co-localized in punctate clusters of Ca V 1.2 channels via that interaction. Ca V 1.2⌬DCT neurons have reduced L-type calcium current, indicating that the distal C-terminal domain is required for normal functional expression in vivo. Deletion of the distal C-terminal domain impairs calcium-dependent signaling from Ca V 1.2 channels to the nucleus, as shown by reduction in phosphorylation of the cAMP response element-binding protein. Our results define AKAP signaling complexes of Ca V 1.2 and Ca V 1.3 channels in brain and reveal three previously unrecognized functional roles for the distal C terminus of neuronal Ca V 1.2 channels in vivo: increased functional expression, anchoring of AKAP15 and PKA, and initiation of excitation-transcription coupling.Voltage-gated calcium channels of the Ca V 1 subfamily conduct L-type calcium currents that transduce cell-surface depolarization into calcium transients and initiate excitation-contraction coupling, excitation-secretion coupling, protein phosphorylation, and gene regulation (1-5). Calcium influx via postsynaptic Ca V 1 channels supports sustained phosphorylation of cAMP response element-binding protein (CREB) 3 and CREB-dependent gene expression in hippocampal neurons (6 -13).Functional Ca V 1 channels are multimeric complexes composed of pore-forming ␣ 1 and associated ␣ 2 ␦, ␤, and in some cases, ␥ subunits (14 -19). These channels have an extended C terminus containing many protein interaction sites for regulation (5). In brain, Ca V 1 channels are composed of 70% Ca V 1.2 and 22% Ca V 1.3 with minor contributions from other Ca V 1 channels, as indicated by immunoprecipitation with specific antibodies (20). Ca V 1.2 and Ca V 1.3 channels are primarily localized in the soma and proximal dendrites (20, 21).The ␤-adrenergic pathway activates cAMP-dependent protein kinase (PKA) and increases the activity of Ca V 1 channels in skeletal and cardiac myocytes and neurons (1-5, 22, 23). PKAmediated regulatio...

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“…What physiological role might be served by this proteolytic processing event? Expression of Ca V 1.1 and Ca V 1.2 channels with truncated C termini in Xenopus oocytes or tsA-201 cells increases the functional activity of these channels (31)(32)(33)(34), suggesting that the distal C terminus has an autoinhibitory effect. Short peptides derived from the distal C-terminal domain inhibit Ca V 1.2 channels (33).…”

Section: Identification Of the C-terminal Amino Acid Residue Of The ␣mentioning

confidence: 99%

“…Expression of Ca V 1.1 and Ca V 1.2 channels with truncated C termini in Xenopus oocytes or tsA-201 cells increases the functional activity of these channels (31)(32)(33)(34), suggesting that the distal C terminus has an autoinhibitory effect. Short peptides derived from the distal C-terminal domain inhibit Ca V 1.2 channels (33). Moreover, coexpression of the distal C-terminal domain as a separate protein with the remainder of Ca V 1.2 channels in tsA-201 cells gives potent inhibition, decreasing …”

Section: Identification Of the C-terminal Amino Acid Residue Of The ␣mentioning

confidence: 99%

Sites of proteolytic processing and noncovalent association of the distal C-terminal domain of Ca_V1.1 channels in skeletal muscle

Hulme

Konoki

Lin

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

112

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In skeletal muscle cells, voltage-dependent potentiation of Ca 2؉ channel activity requires phosphorylation by cAMP-dependent protein kinase (PKA) anchored via an A-kinase anchoring protein (AKAP15), and the most rapid sites of phosphorylation are located in the C-terminal domain. Surprisingly, the site of interaction of the complex of PKA and AKAP15 with the ␣1-subunit of CaV1.1 channels lies in the distal C terminus, which is cleaved from the remainder of the channel by in vivo proteolytic processing. Here we report that the distal C terminus is noncovalently associated with the remainder of the channel via an interaction with a site in the proximal C-terminal domain when expressed as a separate protein in mammalian nonmuscle cells. Deletion mapping of the C terminus of the ␣1-subunit using the yeast two-hybrid assay revealed that a distal C-terminal peptide containing amino acids 1802-1841 specifically interacts with a region in the proximal C terminus containing amino acid residues 1556 -1612. Analysis of the purified ␣1-subunit of CaV1.1 channels from skeletal muscle by saturation sequencing of the intracellular peptides by tandem mass spectrometry identified the site of proteolytic processing as alanine 1664. Our results support the conclusion that a noncovalently associated complex of the ␣1-subunit truncated at A1664 with the proteolytically cleaved distal C-terminal domain, AKAP15, and PKA is the primary physiological form of CaV1.1 channels in skeletal muscle cells.calcium channels ͉ contraction coupling ͉ excitation ͉ protein kinase ͉ proteolysis

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C-terminal Fragments of the α1C(CaV1.2) Subunit Associate with and Regulate L-type Calcium Channels Containing C-terminal-truncated α1CSubunits

Cited by 114 publications

References 23 publications

Non-voltage-gated L-type Ca2+ Channels in Human T Cells

Non-voltage-gated L-type Ca2+ Channels in Human T Cells

Functional Roles of a C-terminal Signaling Complex of CaV1 Channels and A-kinase Anchoring Protein 15 in Brain Neurons

Sites of proteolytic processing and noncovalent association of the distal C-terminal domain of Ca_V1.1 channels in skeletal muscle

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C-terminal Fragments of the α1C(CaV1.2) Subunit Associate with and Regulate L-type Calcium Channels Containing C-terminal-truncated α1CSubunits

Cited by 114 publications

References 23 publications

Non-voltage-gated L-type Ca2+ Channels in Human T Cells

Non-voltage-gated L-type Ca2+ Channels in Human T Cells

Functional Roles of a C-terminal Signaling Complex of CaV1 Channels and A-kinase Anchoring Protein 15 in Brain Neurons

Sites of proteolytic processing and noncovalent association of the distal C-terminal domain of CaV1.1 channels in skeletal muscle

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Product

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Sites of proteolytic processing and noncovalent association of the distal C-terminal domain of Ca_V1.1 channels in skeletal muscle