Expression of cGMP-dependent protein kinase in human atrium

M. MISHRA, M. B. WAGNER, Y-G, WANG, R. W. JOYNER AND R. KUMAR. Expression o f cGMP-dependent Protein Kinase in Human Atrium. Journal of Molecular and C ellular Cardiology (2001) 33, 1467-1476. We have shown that cGMP-dependent protein kinase (PKG) mediates stimulation of L-type calcium current by cGMP in rabbit atrial myocytes. The human atrium may have similar PKG-dependent regulation of calcium current. To elucidate the significance of PKG in car diac function, we have isolated human PKG type I alpha cDNA (+ 1 to 2016), determined the nucleotide sequence and analyzed specific expression of PKG in human atrium. We obtained full-length cDNA of PKG type I alpha from huma n atrial RNA using reverse transcriptase-polymerase chain reaction (RT-PCR) . The coding region of human cardiac PKG Ice showed 99.9% homology to previ ously published human PKG I alpha except for base No, 1983. At this positio n G was substituted for T and this resulted in an amino acid substitution f rom Leu(649) to Phe(649). The cloned PKG I alpha cDNA was expressed in COS cells and the expressed PKG showed cGMP-stimulated PKG enzyme activity and immunoreactivity. Ribonuclease protection assay Western blot analysis, and PKG enzyme activity assays in homogenates from human atrial tissue demonstr ated the presence of PKG mRNA and protein in human atrial tissue. Immunoflu orescence staining confirmed that PKG is highly expressed in human atrial m yocytes, These findings suggest that PKG is highly expressed in human atriu m and that PKG-dependent phosphorylation may be important in regulation of calcium channel activity in human atrial myocytes. (C) 2001 Academic Press.