Abstract 2963: Antibodies Against Cardiac KChIP2 Promote Nuclear Translocation of the Transcription Factor NF-κB in Isolated Rat Cardiomyocytes
BACKGROUND: Mammalian voltage-gated potassium K+ channels are assemblies of pore-forming alpha-subunits and modulating beta-subunits. Kv4 alpha-subunits in the heart and central nervous system require recently identified beta-subunits of the neuronal calcium sensing protein family called K+ channel-interacting proteins (KChIPs). In hearts and endothelial cells, KChIP2 is the predominantly expressed form and exists in 8 different isoforms reflecting splice variants. Previously, we have identified auto-antibodies against the isoform KChIP2.6 in sera from patients with dilated and ischemic cardiomyopathy by surface plasmon resonance analysis. The transcription factor NF-κB plays a central role in inflammation by its ability to induce transcription of pro-inflammatory genes Therefore we investigated whether anti-KChIP2 antibodies might modulate the translocation of the transcription factor.
METHODS: Isolated rat cardiomyocytes were incubated with anti-KChIP2 (2 μg/ml) and additives (see table⇓). After one hour, nuclear proteins were prepared and analysed for the translocation of the NF-κB subunits p52, p65, c-Rel and Rel-B by ELISA. Results are expressed as a percentages ± SEM of controls.
RESULTS: Anti-KChIP2 antibodies induced translocation of the NF-κB subunits p52, p65, c-Rel and RelB from the cytosol to the nucleus, effects which could be prevented by pre-incubation of the antibodies with a blocking peptide for KChIP2 or the NF-κB inhibitor, CAPE (10 ng/ml). Antibodies against green fluorescent protein (GFP), which were raised in the same species as the KChIP2 antibodies, did not modulate NF-κB translocation.
CONCLUSIONS: To our knowledge, the data provide the first evidence that antibodies against cardiac KChIP2 activate the transcription factor NF-κB indicating that KChIP2 antibodies might act as a pro-inflammatory mediator in rat cardiomyocytes.