TY - JOUR
T1 - Nuclear miRNA regulates the mitochondrial genome in the heart
AU - Das, Samarjit
AU - Ferlito, Marcella
AU - Kent, Oliver A.
AU - Fox-Talbot, Karen
AU - Wang, Richard
AU - Liu, Delong
AU - Raghavachari, Nalini
AU - Yang, Yanqin
AU - Wheelan, Sarah J.
AU - Murphy, Elizabeth
AU - Steenbergen, Charles
PY - 2012/6/8
Y1 - 2012/6/8
N2 - Rationale: Mitochondria are semiautonomous cellular organelles with their own genome, which not only supply energy but also participate in cell death pathways. MicroRNAs (miRNAs) are usually 19 to 25 nt long, noncoding RNAs, involved in posttranscriptional gene regulation by binding to the 3′-untranslated regions of target mRNA, which impact on diverse cellular processes. Objective: To determine if nuclear miRNAs translocate into the mitochondria and regulate mitochondrial function with possible pathophysiological implications in cardiac myocytes. Methods and Results: We find that miR-181c is encoded in the nucleus, assembled in the cytoplasm, and finally translocated into the mitochondria of cardiac myocytes. Immunoprecipitation of Argonaute 2 from the mitochondrial fraction indicates binding of cytochrome c oxidase subunit 1 (mt-COX1) mRNA from the mitochondrial genome with miR-181c. Also, a luciferase reporter construct shows that mi-181c binds to the 3′UTR of mt-COX1. To study whether miR-181c regulates mt-COX1, we overexpressed precursor miR-181c (or a scrambled sequence) in primary cultures of neonatal rat ventricular myocytes. Overexpression of miR-181c did not change mt-COX1 mRNA but significantly decreased mt-COX1 protein, suggesting that miR-181c is primarily a translational regulator of mt-COX1. In addition to altering mt-COX1, overexpression of miR-181c results in increased mt-COX2 mRNA and protein content, with an increase in both mitochondrial respiration and reactive oxygen species generation in neonatal rat ventricular myocytes. Thus, our data show for the first time that miR-181c can enter and target the mitochondrial genome, ultimately causing electron transport chain complex IV remodeling and mitochondrial dysfunction. Conclusions: Nuclear miR-181c translocates into the mitochondria and regulates mitochondrial genome expression. This unique observation may open a new dimension to our understanding of mitochondrial dynamics and the role of miRNA in mitochondrial dysfunction.
AB - Rationale: Mitochondria are semiautonomous cellular organelles with their own genome, which not only supply energy but also participate in cell death pathways. MicroRNAs (miRNAs) are usually 19 to 25 nt long, noncoding RNAs, involved in posttranscriptional gene regulation by binding to the 3′-untranslated regions of target mRNA, which impact on diverse cellular processes. Objective: To determine if nuclear miRNAs translocate into the mitochondria and regulate mitochondrial function with possible pathophysiological implications in cardiac myocytes. Methods and Results: We find that miR-181c is encoded in the nucleus, assembled in the cytoplasm, and finally translocated into the mitochondria of cardiac myocytes. Immunoprecipitation of Argonaute 2 from the mitochondrial fraction indicates binding of cytochrome c oxidase subunit 1 (mt-COX1) mRNA from the mitochondrial genome with miR-181c. Also, a luciferase reporter construct shows that mi-181c binds to the 3′UTR of mt-COX1. To study whether miR-181c regulates mt-COX1, we overexpressed precursor miR-181c (or a scrambled sequence) in primary cultures of neonatal rat ventricular myocytes. Overexpression of miR-181c did not change mt-COX1 mRNA but significantly decreased mt-COX1 protein, suggesting that miR-181c is primarily a translational regulator of mt-COX1. In addition to altering mt-COX1, overexpression of miR-181c results in increased mt-COX2 mRNA and protein content, with an increase in both mitochondrial respiration and reactive oxygen species generation in neonatal rat ventricular myocytes. Thus, our data show for the first time that miR-181c can enter and target the mitochondrial genome, ultimately causing electron transport chain complex IV remodeling and mitochondrial dysfunction. Conclusions: Nuclear miR-181c translocates into the mitochondria and regulates mitochondrial genome expression. This unique observation may open a new dimension to our understanding of mitochondrial dynamics and the role of miRNA in mitochondrial dysfunction.
KW - Cytochrome c oxidase
KW - MiR
KW - MicroRNA
KW - Mitochondria
KW - Reactive oxygen species
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U2 - 10.1161/CIRCRESAHA.112.267732
DO - 10.1161/CIRCRESAHA.112.267732
M3 - Article
C2 - 22518031
AN - SCOPUS:84862279805
SN - 0009-7330
VL - 110
SP - 1596
EP - 1603
JO - Circulation research
JF - Circulation research
IS - 12
ER -