Identification of Two Nervous System-Specific Members of theergPotassium Channel Gene Family

Abstract

Two new potassium channel genes, erg2 and erg3, that are expressed in the nervous system of the rat were identified. These two genes form a small gene family with the previously described erg1 (HERG) gene. The erg2 and erg3 genes are expressed exclusively in the nervous system, in marked contrast to erg1, which is expressed in both neural and non-neural tissues. All three genes are expressed in peripheral sympathetic ganglia. The erg3 channel produces a current that has a large transient component at positive potentials, whereas the other two channels are slowly activating delayed rectifiers. Expression of the erg1 gene in the sympathetic nervous system has potential implications for the etiology of the LQT2 form of the human genetic disease long QT syndrome.

Do Glia Have Heart? Expression and Functional Role forEther-A-Go-GoCurrents in Hippocampal Astrocytes

“…However, pharmacological subtraction of whole-cell currents revealed that the properties of astrocytic ERG are similar to those reported for cloned HERG1 (Fig. 1 B2) (Shi et al, 1997). The presence of rat ERG1 was further confirmed by RT-PCR experiments in cultured glia.…”

“…Furthermore, the characteristic time and voltage dependence of ERG produces large inward and only small outward whole-cell currents (Warmke and Ganetzky, 1994), resulting in apparent inward-going rectification such as seen in CNS astrocytes. Recently the molecular properties of two additional members of the ERG subfamily (ERG2 and ERG3), which are selectively expressed in the nervous system, have been described (Shi et al, 1997), and ERG currents have been recorded from microglia (Zhou et al, 1998). However, a role for these currents in the CNS remains elusive.…”

“…At least three genes encode ERG currents in the mammalian nervous system (Shi et al, 1997). Although ERG2-3 appear to be exclusively expressed in nervous tissues, ERG1 is found in both nervous and non-nervous cells.…”

Functional evolution of Erg potassium channel gating reveals an ancient origin for I Kr

“…The net effect is that peak Erg1 current flow is delayed and specifically accelerates cardiac action potential plateau repolarization (15), and the length of the plateau is dependent on Erg1 current density (16). The physiological role of mammalian Erg2 and Erg3 channels has not been extensively characterized, but they share an I Kr -like gating phenotype (17).…”

HERG1 gene expression as a specific tumor marker in colorectal tissues

“…In contrast to brain, heart and lactotrophs, where HERG-related K + channels are physiologically expressed [12][13][14][15], they have been found to be over-expressed in several tumor cell lines of different histogenesis [16,17]. Furthermore, Cherubini and colleagues found a high frequency of HERG expression in primary human endometrial cancers as compared to normal and hyperplastic endometrium and therefore nominated this protein as a potential indicator of cancerous versus hyperplastic endometrial growth [18].…”