Alternative splicing and polyadenylation contribute to the generation of hERG1 C-terminal isoforms.
The human ether-a-go-go-related gene 1 (hERG1) encodes the pore-forming subunit of the rapidly activating delayed rectifier potassium channel. Several hERG1 isoforms with different N- and C-terminal ends have been identified. The hERG1a, hERG1b, and hERG1-3.1 isoforms contain the full-length C terminus, whereas the hERG1(USO) isoforms, hERG1a(USO) and hERG1b(USO), lack most of the C-terminal domain and contain a unique C-terminal end. The mechanisms underlying the generation of hERG1(USO) isoforms are not understood. We show that hERG1 isoforms with different C-terminal ends are generated by alternative splicing and polyadenylation of hERG1 pre-mRNA. We identified an intrinsically weak, noncanonical poly(A) signal, AGUAAA, within intron 9 of hERG1 that modulates the expression of hERG1a and hERG1a(USO). Replacing AGUAAA with the strong, canonical poly(A) signal AAUAAA resulted in the predominant production of hERG1a(USO) and a marked decrease in hERG1 current. In contrast, eliminating the intron 9 poly(A) signal or increasing the strength of 5' splice site led to the predominant production of hERG1a and a significant increase in hERG1 current. We found significant variation in the relative abundance of hERG1 C-terminal isoforms in different human tissues. Taken together, these findings suggest that post-transcriptional regulation of hERG1 pre-mRNA may represent a novel mechanism to modulate the expression and function of hERG1 channels.
Gong
Qiuming
Q
Division of Cardiovascular Medicine, Department of Medicine, Oregon Health & Science University, Portland, Oregon 97239, USA.
Stump
Matthew R
MR
Dunn
A Russell
AR
Deng
Vivianne
V
Zhou
Zhengfeng
Z
D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D018408:Patch-Clamp Techniques; D026723:Polyadenylation; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D014018:Tissue Distribution
D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; D020033:Protein Isoforms; D012322:RNA Precursors