miR-181c Activates Mitochondrial Calcium Uptake by Regulating MICU1 in the Heart

• Published in: Journal of the American Heart Association 2019-12, Vol.8 (24), p.e012919
• Main Authors: Banavath, Hemanth N, Roman, Barbara, Mackowski, Nathan, Biswas, Debjit, Afzal, Junaid, Nomura, Yohei, Solhjoo, Soroosh, O'Rourke, Brian, Kohr, Mark, Murphy, Elizabeth, Steenbergen, Charles, Das, Samarjit
• Format: Article
• Language: English
• Subjects: Animals; Calcium - metabolism; Calcium-Binding Proteins - physiology; heart failure; Male; Mice; Mice, Inbred C57BL; microRNA; MicroRNAs - physiology; miRNA; mitochondria; Mitochondria, Heart - metabolism; mitochondrial calcium; Mitochondrial Membrane Transport Proteins - physiology; mitomiR; Original Research
• ISSN: 2047-9980; 2047-9980
• DOI: 10.1161/JAHA.119.012919

Background Translocation of miR-181c into cardiac mitochondria downregulates the mitochondrial gene, mt-COX1. miR-181c/d hearts experience less oxidative stress during ischemia/reperfusion (I/R) and are protected against I/R injury. Additionally, miR-181c overexpression can increase mitochondrial matrix Ca ([Ca ] ), but the mechanism by which miR-181c regulates [Ca ] is unknown. Methods and Results By RNA sequencing and analysis, here we show that hearts from miR-181c/d mice overexpress nuclear-encoded Ca regulatory and metabolic pathway genes, suggesting that alterations in miR-181c and mt-COX1 perturb mitochondria-to-nucleus retrograde signaling and [Ca ] regulation. Quantitative polymerase chain reaction validation of transcription factors that are known to initiate retrograde signaling revealed significantly higher Sp1 (specificity protein) expression in the miR-181c/d hearts. Furthermore, an association of Sp1 with the promoter region of MICU1 was confirmed by chromatin immunoprecipitation-quantitative polymerase chain reaction and higher expression of MICU1 was found in the miR-181c/d hearts. Conversely, downregulation of Sp1 by small interfering RNA decreased MICU1 expression in neonatal mouse ventricular myocytes. Changes in PDH activity provided evidence for a change in [Ca ] via the miR-181c/MICU1 axis. Moreover, this mechanism was implicated in the pathology of I/R injury. When MICU1 was knocked down in the miR-181c/d heart by lentiviral expression of a short-hairpin RNA against MICU1, cardioprotective effects against I/R injury were abrogated. Furthermore, using an in vitro I/R model in miR-181c/d neonatal mouse ventricular myocytes, we confirmed the contribution of both Sp1 and MICU1 in ischemic injury. Conclusions miR-181c regulates mt-COX1, which in turn regulates MICU1 expression through the Sp1-mediated mitochondria-to-nucleus retrograde pathway. Loss of miR-181c can protect the heart from I/R injury by modulating [Ca ] through the upregulation of MICU1.