Affiliation:
1. Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705
Abstract
Coordinated expression of ion channels is crucial for cardiac rhythms, neural signaling, and cell cycle progression. Perturbation of this balance results in many disorders including cardiac arrhythmias. Prior work revealed association of mRNAs encoding cardiac Na
V
1.5 (
SCN5A
) and hERG1 (
KCNH2
), but the functional significance of this association was not established. Here, we provide a more comprehensive picture of
KCNH2
,
SCN5A
,
CACNA1C
, and
KCNQ1
transcripts collectively copurifying with nascent hERG1, Na
V
1.5, Ca
V
1.2, or KCNQ1 channel proteins. Single-molecule fluorescence in situ hybridization (smFISH) combined with immunofluorescence reveals that the channel proteins are synthesized predominantly as heterotypic pairs from discrete molecules of mRNA, not as larger cotranslational complexes. Puromycin disrupted colocalization of mRNA with its encoded protein, as expected, but remarkably also pairwise mRNA association, suggesting that transcript association relies on intact translational machinery or the presence of the nascent protein. Targeted depletion of
KCHN2
by specific shRNA resulted in concomitant reduction of all associated mRNAs, with a corresponding reduction in the encoded channel currents. This co-knockdown effect, originally described for
KCNH2
and
SCN5A
, thus appears to be a general phenomenon among transcripts encoding functionally related proteins. In multielectrode array recordings, proarrhythmic behavior arose when I
Kr
was reduced by the selective blocker dofetilide at IC
50
concentrations, but not when equivalent reductions were mediated by shRNA, suggesting that co-knockdown mitigates proarrhythmic behavior expected from the selective reduction of a single channel species. We propose that coordinated, cotranslational association of functionally related ion channel mRNAs confers electrical stability by co-regulating complementary ion channels in macromolecular complexes.
Funder
HHS | National Institutes of Health
American Heart Association
HHS | NIH | National Institute of Neurological Disorders and Stroke
Publisher
Proceedings of the National Academy of Sciences
Cited by
1 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献