During late rat embryonic development, KCNE2 is transcribed predominantly in atrial and ventricular myocardium, while KCNH2 is expressed more ubiquitously in cardiac and non-cardiac tissues.
The co-expression of KCNH2 and KCNE2 in the fetal rat myocardium suggests they assemble to form cardiac IKr channels during late embryonic development.
To understand molecular mechanisms that regulate formation and maintenance of cardiac IKr (rapidly activating component of the delayed rectifier K+ current), we have investigated the spatiotemporal expression pattern of two rat potassium voltage-gated channels, namely subfamily H (eag-related), member2 (KCNH2) (alias name: rERG) and Isk-related family, member2 (KCNE2) (alias name: rMiRP1) during late embryonic development by means of the in situ hybridization technique. KCNE2 is transcribed predominantly in atrial und ventricular myocardium at stages E14.5-E18.5dpc and only a minor signal emerged in the tongue at E16.5dpc. In contrast, KCNH2 transcripts appeared in a less confined pattern with intense signals in atrial and ventricular myocardium, somites, spinal cord, bowel system, central nervous system and thymus at stages E14.5-E18.5dpc. Non-cardiac expression even exceeds the intensity of the cardiac signal, indicating that KCNH2 contributes to K+ currents in non-cardiac tissue as well. Transcription of the rat b-subunit KCNE2 is present in all regions of the fetal myocardium and co-distributes perfectly with transcription of the pore forming a-subunit KCNH2. It seems likely that KCNH2 and KCNE2 are linked to form cardiac IKr channels, associated to cardiogenesis and cardiomyocyte excitability.
Chun et al. (Sun,) conducted a other in Late embryonic development of the rat heart. In situ hybridization of KCNH2 and KCNE2 was evaluated on Spatiotemporal expression pattern of KCNH2 and KCNE2. During late rat embryonic development, KCNE2 is transcribed predominantly in atrial and ventricular myocardium, while KCNH2 is expressed more ubiquitously in cardiac and non-cardiac tissues.