Antibodies against potassium channel interacting protein 2 induce necrosis in isolated rat cardiomyocytes.
Auto-antibodies against cardiac proteins have been described in patients with dilated cardiomyopathy. Antibodies against the C-terminal part of KChIP2 (anti-KChIP2 [C-12]) enhance cell death of rat cardiomyocytes. The underlying mechanisms are not fully understood. Therefore, we wanted to explore the mechanisms responsible for anti-KChIP2-mediated cell death. Rat cardiomyocytes were treated with anti-KChIP2 (C-12). KChIP2 RNA and protein expressions, nuclear NF-κB, mitochondrial membrane potential Δψm, caspase-3 and -9 activities, necrotic and apoptotic cells, total Ca(2+) and K(+) concentrations, and the effects on L-type Ca(2+) channels were quantified. Anti-KChIP2 (C-12) induced nuclear translocation of NF-κB. Anti-KChIP2 (C-12)-treatment for 2 h significantly reduced KChIP2 mRNA and protein expression. Anti-KChIP2 (C-12) induced nuclear translocation of NF-κB after 1 h. After 6 h, Δψm and caspase-3 and -9 activities were not significantly changed. After 24 h, anti-KChIP2 (C-12)-treated cells were 75 ± 3% necrotic, 2 ± 1% apoptotic, and 13 ± 2% viable. Eighty-six ± 1% of experimental buffer-treated cells were viable. Anti-KChIP2 (C-12) induced significant increases in total Ca(2+) (plus 11 ± 2%) and K(+) (plus 18 ± 2%) concentrations after 5 min. Anti-KChIP2 (C-12) resulted in an increased Ca(2+) influx through L-type Ca(2+) channels. In conclusion, our results suggest that anti-KChIP2 (C-12) enhances cell death of rat cardiomyocytes probably due to necrosis.
Department of Internal Medicine B, University Medicine Greifswald, Greifswald, Germany.
Sangita
S
Choudhury
Michael
M
Schnell
Thomas
T
Bühler
Yvonne
Y
Reinke
Jan
J
Lüdemann
Felix
F
Nießner
Heinrich
H
Brinkmeier
Lars R
LR
Herda
Alexander
A
Staudt
Heyo K
HK
Kroemer
Uwe
U
Völker
Stephan B
SB
Felix
Martin
M
Landsberger
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001323:Autoantibodies / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D020672:I-kappa B Proteins / Q000378:metabolism; D051605:Kv Channel-Interacting Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D016328:NF-kappa B / Q000378:metabolism; D009336:Necrosis / Q000188:drug therapy; D011188:Potassium / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology
D001323:Autoantibodies; D020746:Calcium Channels, L-Type; D020672:I-kappa B Proteins; C496755:Kcnip2 protein, mouse; D051605:Kv Channel-Interacting Proteins; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D053148:Caspase 3; D053453:Caspase 9; D011188:Potassium; D002118:Calcium
CARDIOMYOCYTE; CELL DEATH; KCHIP2; KV CHANNEL INTERACTION PROTEIN 2