Sequence and structure-specific elements of HERG mRNA determine channel synthesis and trafficking efficiency.
Human ether-á-gogo-related gene (HERG) encodes a potassium channel that is highly susceptible to deleterious mutations resulting in susceptibility to fatal cardiac arrhythmias. Most mutations adversely affect HERG channel assembly and trafficking. Why the channel is so vulnerable to missense mutations is not well understood. Since nothing is known of how mRNA structural elements factor in channel processing, we synthesized a codon-modified HERG cDNA (HERG-CM) where the codons were synonymously changed to reduce GC content, secondary structure, and rare codon usage. HERG-CM produced typical IKr-like currents; however, channel synthesis and processing were markedly different. Translation efficiency was reduced for HERG-CM, as determined by heterologous expression, in vitro translation, and polysomal profiling. Trafficking efficiency to the cell surface was greatly enhanced, as assayed by immunofluorescence, subcellular fractionation, and surface labeling. Chimeras of HERG-NT/CM indicated that trafficking efficiency was largely dependent on 5' sequences, while translation efficiency involved multiple areas. These results suggest that HERG translation and trafficking rates are independently governed by noncoding information in various regions of the mRNA molecule. Noncoding information embedded within the mRNA may play a role in the pathogenesis of hereditary arrhythmia syndromes and could provide an avenue for targeted therapeutics.
['Sroubek|Jakub|J|', 'Krishnan|Yamini|Y|', 'McDonald|Thomas V|TV|']
D001482:Base Composition D002462:Cell Membrane D003062:Codon D018076:DNA, Complementary D000072237:ERG1 Potassium Channel D051638:Ether-A-Go-Go Potassium Channels D057809:HEK293 Cells D006801:Humans D015151:Immunoblotting D015640:Ion Channel Gating D008564:Membrane Potentials D008856:Microscopy, Fluorescence D009154:Mutation D018408:Patch-Clamp Techniques D014176:Protein Biosynthesis D017433:Protein Structure, Secondary D021381:Protein Transport D012333:RNA, Messenger
KCNH2 LQTS SNP codon-usage protein translation