Abstract P3039: The Biophysical Action Of Microrna-1 Is Critical To Maintaining The Homeostasis Of The Heart

• Published in: Circulation research 2023-08, Vol.133 (Suppl_1)
• Main Authors: Yang, Dandan, Wan, Xiaoping, Kacira, Ege, xu, Xianyao, Tang, Feng, Hund, Thomas J, Mohler, Peter J, Deschenes, Isabelle, Fu, Jidong A
• Format: Article
• Language: English
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/res.133.suppl_1.P3039

Abstract only MicroRNAs (miRs) are evolutionarily-conserved small noncoding RNAs (~22 nucleotides) and are involved in most biological events through the classical mechanism of RNA interference (RNAi). Recently, we discovered a novel action of miR to biophysically modulate the function of bound proteins. miR1, the most predominant miR in the heart, physically binds to the inward rectifier potassium channel Kir2.1, directly represses the I K1 current, and biophysically modulates cardiac electrophysiology. An arrhythmia-associated human single nucleotide polymorphism of miR1 (hSNP14A/G) specifically disrupts biophysical modulation while retaining the RNAi function. However, the physiological significance of miR’s biophysical action on the heart remains unknown. To study this, we created hSNP14A/G single nucleotide mutation on miR1-1 and miR1-2 by using CRISPR/Cas9 technology and successfully generated 14G-mutated transgenic homozygous mice (14G-Homo, miR1-1 14G/G :miR1-2 14G/G ), in which the mutated miR1 maintains the RNAi while with a specific deletion of the biophysical action. We found that 14G-Homo mice had high mortality with impaired heart pumping function and some mice developed heart failure at 6 months of age. The whole transcriptome RNA-sequencing assays revealed cardiac electrical remodeling in 14G-Homo hearts. Consistently, 14G-Homo hearts had prolonged QRS and QT intervals with slower electrical conduction through the ventricle, and 14G-Homo mice are susceptible to arrhythmia. Our patch clamping showed that 14G-Homo cardiomyocytes had significantly prolonged action potential with bigger I K1 and L-type Ca 2+ current (I Ca,L ) than WT cells. We also performed a CLIP RNA pulldown-mass spectrometry assay and identified more ion channel proteins that interact with miR1. From the validation, miR1 biophysically suppresses I Ca,L via directly binding to Cavβ2, the β subunit of the voltage-gated Ca 2+ channel. We conclude that miR1 biophysically modulates the function of the heart, which is critical to maintaining heart homeostasis. Our discovery expands the biological significance of miR biology and broadens its implication of RNA medicine development for cardiovascular diseases.