Concordant expression of KChIP2 mRNA, protein and transient outward current throughout the canine ventricle.
Expression of the transient outward K+ current (Ito) was analysed in nine different regions of the canine ventricle. In addition to the previously described transmural gradients in the right and left ventricular free walls, an inverted U-shaped pattern of Ito expression was observed in the interventricular septum. The mRNA and protein expression for the K+ channel beta subunit KChIP2 were examined in the same tissues. The KChIP2 protein levels closely matched mRNA expression in all regions of the ventricle and paralleled the density of Ito. The global pattern of gene expression in human epicardial and endocardial tissue was examined using microarrays. Only 0.1 % of the genes expressed in the human ventricle displayed the same expression pattern as the KChIP2 gene in left ventricle. It is unlikely, therefore, that the reported distribution of KChIP2 protein within the ventricle can be explained by a cross-reaction of the anti-KChIP2 antibody with a different protein. It is concluded that transcriptional regulation of the KChIP2 gene is a primary determinant of Ito expression in heart.
Rosati
Barbara
B
Department of Physiology and Biophysics, Institute of Molecular Cardiology, State University of New York at Stony Brook, NY 11794, USA.
Grau
Frederic
F
Rodriguez
Samantha
S
Li
Huilin
H
Nerbonne
Jeanne M
JM
McKinnon
David
D
D000818:Animals; D002135:Calcium-Binding Proteins / Q000235:genetics*; D002552:Cerebral Ventricles / Q000502:physiology*; D004285:Dogs; D007839:Functional Laterality; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006321:Heart / Q000502:physiology*; D051605:Kv Channel-Interacting Proteins; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000235:genetics; D014176:Protein Biosynthesis; D014158:Transcription, Genetic
D002135:Calcium-Binding Proteins; C496755:Kcnip2 protein, mouse; D051605:Kv Channel-Interacting Proteins; D015221:Potassium Channels