Variability in Cardiac miRNA-122 Level Determines Therapeutic Potential of miRNA-Regulated AAV Vectors

Abstract

Systemically delivered adeno-associated viral vector serotype 9 (AAV9) effectively transduces murine heart, but provides transgene expression also in liver and skeletal muscles. Improvement of the selectivity of transgene expression can be achieved through incorporation of target sites (TSs) for miRNA-122 and miRNA-206 into the 3 0 untranslated region (3 0 UTR) of the expression cassette. Here, we aimed to generate such miRNA-122-and miRNA-206-regulated AAV9 vector for a therapeutic, heart-specific overexpression of heme oxygenase-1 (HO-1). We successfully validated the vector functionality in murine cell lines corresponding to tissues targeted by AAV9. Next, we evaluated biodistribution of transgene expression following systemic vector delivery to HO-1-deficient mice of mixed C57BL/6J Â FVB genetic background. Although AAV genomes were present in the hearts of these animals, HO-1 protein expression was either absent or significantly impaired. We found that miRNA-122, earlier described as liver specific, was present also in the hearts of C57BL/6J Â FVB mice. Various levels of miRNA-122 expression were observed in the hearts of other mouse strains, in heart tissues of patients with cardiomyopathy, and in human induced pluripotent stem cell-derived cardiomyocytes in which we also confirmed such posttranscriptional regulation of transgene expression. Our data clearly indicate that therapeutic utilization of miRNA-based regulation strategy needs to consider inter-individual variability.

Connexin 43 and Connexin 26 Involvement in the Ponatinib-Induced Cardiomyopathy: Sex-Related Differences in a Murine Model

“…Other molecules were differently regulated in female and male mice hearts by ponatinib treatment, and, among these, our focus was on those related to Cx43. Namely, signal-regulated kinase (ERK), kinase B (Akt), microRNA122 (miR-122), and interleukin-6 (IL-6) were analyzed [ 14 , 15 , 16 , 17 ].…”

“…This miRNA appears to be directly implicated in the development of cardiovascular diseases and its inhibition plays antifibrotic, anti-apoptotic, anti-inflammatory, and antioxidant functions [ 16 ]. MiR-122 could be linked to Cxs for their own involvement in miRNA intercellular transfer [ 15 ]. Thus, we can speculate that the observed reduction in cardiac Cx43 and Cx26 in female hearts could be, in part, responsible for miR-122 down regulation.…”

Role of Heme-Oxygenase-1 in Biology of Cardiomyocytes Derived from Human Induced Pluripotent Stem Cells

“…Differentiated hiPSC-CMs were phenotyped as described previously [ 20 ]. Shortly, on day 20–24 of differentiation, cardiomyocytes were harvested, fixed, and stained for TNNT2 (Cardiac Troponin T Monoclonal Antibody, 1:1000, clone 13–11; ThermoFisher Scientific).…”

Of rAAV and Men: From Genetic Neuromuscular Disorder Efficacy and Toxicity Preclinical Studies to Clinical Trials and Back

“…MiR-122 was also shown to be present in the human cardiac tissues of patients with cardiomyopathy and in human iPSC-derived cardiomyocytes. The cardiac expression showed high variability between different mouse strains, sexes and human individuals [ 289 ]. This publication challenges the liver-specificity of miR-122 and warns against miRNA inter-individual variability.…”

“…To our knowledge, no clinical trial has used miRNA TS in the cassette to date. If it ever happens, checking beforehand the mean level of the targeted miRNA in the treated population will be essential, as miRNA expression can substantially vary between individuals, sexes or pathologies [ 289 , 290 , 291 ].…”