Document Type

Article

Publication Date

2018

Abstract

TheKCNH2 gene encodes the hERG potassium channel that conducts the rapidly activating delayed rectifier current in the heart. Two C-terminal hERG isoforms are expressed in the heart. Splicing of KCNH2 intron 9 leads to the formation of a full-length, functional hERGa isoform and polyadenylation of intron 9 results in the production of a non-functional, C-terminally truncated hERGa-USO isoform. In the heart, only one-third of KCNH2 pre-mRNA is processed to hERGa due to inefficient intron 9 splicing. A unique feature ofKCNH2 intron 9 is the presence of a 25 nt adenosine stretch immediately downstream of the weak, noncanonical, polyadenylation site, AGTAAA. Interestingly, non-human primate species contain the AGTAAA poly(A) site, but differ in the length of the downstream poly(A) stretch. It is not known how the length of the adenosine stretch effects the alternative processing of KCNH2 and the generation of C-terminal hERG isoforms. To test the effect of adenosine stretch length on alternative processing, the KCNH2 intron 9 poly(A) stretch was changed from 25 nt to 13 nt and 33 nt, corresponding to the sequences of the marmoset and baboon. In the presence of a 13 nt adenosine stretch, intron 9 splicing outcompeted polyadenylation and resulted in two-thirds of KCNH2 pre-mRNA being processed to hERGa. Introducing the 33 nt adenosine stretch into intron 9 also resulted in increased hERGa expression and concomitantly decreased expression of the hERGa-USO isoform. Whole-cell patch clamp analyses showed increased hERG current in HEK-293 cells transfected with full-length KCNH2 gene constructs containing 13 nt and 33 nt adenosine stretches. Although the expression of hERGa-USO has not been previously 130a Sunday, February 18, 2018 reported in other species, our present findings suggest that length of the poly(A) stretch within KCNH2 contributes to the species-specific regulation of hERG C-terminal isoform expression.

Comments

Originally Published in:

Biophysical Journal, Volume 114, Issue 3, Supplement 1. 130A-131A. 2018

DOI: 10.1016/j.bpj.2017.11.740

Download

Included in

Biology Commons

Share

COinS