RGD Reference Report - Functional characterization of CaValpha2delta mutations associated with sudden cardiac death. - Rat Genome Database

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Functional characterization of CaValpha2delta mutations associated with sudden cardiac death.

Authors: Bourdin, B  Shakeri, B  Tetreault, MP  Sauve, R  Lesage, S  Parent, L 
Citation: Bourdin B, etal., J Biol Chem. 2015 Jan 30;290(5):2854-69. doi: 10.1074/jbc.M114.597930. Epub 2014 Dec 19.
RGD ID: 11059598
Pubmed: PMID:25527503   (View Abstract at PubMed)
PMCID: PMC4317020   (View Article at PubMed Central)
DOI: DOI:10.1074/jbc.M114.597930   (Journal Full-text)

L-type Ca(2+) channels play a critical role in cardiac rhythmicity. These ion channels are oligomeric complexes formed by the pore-forming CaValpha1 with the auxiliary CaVbeta and CaValpha2delta subunits. CaValpha2delta increases the peak current density and improves the voltage-dependent activation gating of CaV1.2 channels without increasing the surface expression of the CaValpha1 subunit. The functional impact of genetic variants of CACNA2D1 (the gene encoding for CaValpha2delta), associated with shorter repolarization QT intervals (the time interval between the Q and the T waves on the cardiac electrocardiogram), was investigated after recombinant expression of the full complement of L-type CaV1.2 subunits in human embryonic kidney 293 cells. By performing side-by-side high resolution flow cytometry assays and whole-cell patch clamp recordings, we revealed that the surface density of the CaValpha2delta wild-type protein correlates with the peak current density. Furthermore, the cell surface density of CaValpha2delta mutants S755T, Q917H, and S956T was not significantly different from the cell surface density of the CaValpha2delta wild-type protein expressed under the same conditions. In contrast, the cell surface expression of CaValpha2delta D550Y, CaValpha2delta S709N, and the double mutant D550Y/Q917H was reduced, respectively, by approximately 30-33% for the single mutants and by 60% for the latter. The cell surface density of D550Y/Q917H was more significantly impaired than protein stability, suggesting that surface trafficking of CaValpha2delta was disrupted by the double mutation. Co-expression with D550Y/Q917H significantly decreased CaV1.2 currents as compared with results obtained with CaValpha2delta wild type. It is concluded that D550Y/Q917H reduced inward Ca(2+) currents through a defect in the cell surface trafficking of CaValpha2delta. Altogether, our results provide novel insight in the molecular mechanism underlying the modulation of CaV1.2 currents by CaValpha2delta.



Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process

  

Cellular Component

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Cacna2d1RatL-type voltage-gated calcium channel complex part_ofIDA PMID:25527503BHF-UCL 
Cacnb3RatL-type voltage-gated calcium channel complex part_ofIDA PMID:25527503BHF-UCL 

Molecular Function

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Cacnb3Ratcalcium channel regulator activity enablesIDA PMID:25527503BHF-UCL 

Objects Annotated

Genes (Rattus norvegicus)
Cacna2d1  (calcium voltage-gated channel auxiliary subunit alpha2delta 1)
Cacnb3  (calcium voltage-gated channel auxiliary subunit beta 3)


Additional Information