MicroRNA-dependent suppression of biological pacemaker activity induced by TBX18.
Publication Year:
2022
PubMed ID:
36543116
Funding Grants:
Public Summary:
Chemically modified mRNA (CMmRNA) can be used to deliver therapeutic genes into cells, but sometimes the body limits how much protein is made. In this study, researchers delivered a gene called TBX18 using CMmRNA into heart cells and rats with heart rhythm issues. They found that the protein made from this mRNA was weak and short-lived. However, when they blocked certain molecules called microRNAs (miRs) that were suppressing the mRNA, the amount of TBX18 protein increased and lasted longer—enough to help the heart generate electrical signals. This approach also worked with another gene, VEGF-A, involved in forming new blood vessels.
Scientific Abstract:
Chemically modified mRNA (CMmRNA) with selectively altered nucleotides are used to deliver transgenes, but translation efficiency is variable. We have transfected CMmRNA encoding human T-box transcription factor 18 (CMmTBX18) into heart cells or the left ventricle of rats with atrioventricular block. TBX18 protein expression from CMmTBX18 is weak and transient, but Acriflavine, an Argonaute 2 inhibitor, boosts TBX18 levels. Small RNA sequencing identified two upregulated microRNAs (miRs) in CMmTBX18-transfected cells. Co-administration of miR-1-3p and miR-1b antagomiRs with CMmTBX18 prolongs TBX18 expression in vitro and in vivo and is sufficient to generate electrical stimuli capable of pacing the heart. Different suppressive miRs likewise limit the expression of VEGF-A CMmRNA. Cells therefore resist translation of CMmRNA therapeutic transgenes by upregulating suppressive miRs. Blockade of suppressive miRs enhances CMmRNA expression of genes driving biological pacing or angiogenesis. Such counterstrategies constitute an approach to boost the efficacy and efficiency of CMmRNA therapies.