Adenovirus-mediated gene transfer reconstitutes depressed sarcoplasmic reticulum Ca2+-ATPase levels and shortens prolonged cardiac myocyte Ca2+ transients.
BACKGROUND
Decreased expression of the sarcoplasmic reticulum (SR) Ca2+-ATPase of the cardiac myocyte (SERCA2) and abnormal Ca2+ regulation have been independently linked to human heart failure. This study was designed to determine whether expression of a SERCA2 transgene could reconstitute depressed cardiac myocyte SERCA2 levels, augment SR Ca2+ uptake, and shorten prolonged excitation-contraction (EC)-associated Ca2+ transients in neonatal rat cardiac myocytes (NM).


RESULTS
Cultured NM were treated with phorbol-12-myristate-13-acetate (PMA), a compound that decreases endogenous SERCA2 expression and results in prolongation of EC-associated Ca2+ transients. PMA-treated NM had a 75% reduction in SERCA2 mRNA and a 40% reduction in SERCA2 protein levels. SERCA2 adenovirus infection increased SERCA2 mRNA expression to 2.5 times control and reconstituted SERCA2 protein levels in PMA-treated cells. This reconstitution was associated with a 32.4% reduction in the time for decline of the Indo-1 Ca2+ transient to half-maximum levels (t(1/2) [Ca2+]i) (P<.05). A 34.5% augmentation of oxalate-facilitated SR Ca2+ uptake was also documented in SERCA2 adenovirus-infected cells (P<.05).


CONCLUSIONS
Adenovirus-mediated expression of a SERCA2 transgene can reconstitute depressed endogenous SERCA2 levels, shorten prolonged Ca2+ transients, and augment SR Ca2+ uptake. It is conceivable that such an approach might be used in vivo to normalize altered Ca2+ regulation in human heart failure.
Giordano
F J
FJ
Department of Medicine, University of California at San Diego in La Jolla, USA. fgiordano@ucsd.edu
He
H
H
McDonough
P
P
Meyer
M
M
Sayen
M R
MR
Dillmann
W H
WH
D000256:Adenoviridae; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D006801:Humans; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
D000252:Calcium-Transporting ATPases; D002118:Calcium