Abstract 3060: MicroRNA-210 Controls Metabolic Adaptation During Hypoxia in Pulmonary Vascular Endothelium
Background: In response to hypoxia, pulmonary arterial endothelial cells (PAECs) undergo metabolic adaptations important in pulmonary vascular function in health and disease. Louis Pasteur first described a fundamental metabolic response to hypoxia, resulting from a shift from mitochondrial oxidative phosphorylation to glycolysis. This “Pasteur effect” profoundly influences cell survival and function, but the underlying molecular mechanisms are unclear. Hypoxia-induced microRNA (miRNA) may represent non-canonical regulatory factors that modulate the Pasteur effect in pulmonary vascular endothelium.
Methods and Results: In human PAECs, only microRNA-210 (miR-210) is robustly up-regulated (30.41 fold change ± 4.15619 SEM) by hypoxia, as assessed by quantitative polymerase chain reaction. Through bioinformatics algorithms and reporter/gene expression assays, the iron-sulfur cluster assembly proteins (ISCU1/2) were identified as direct targets for repression by miR-210. ISCU1/2 direct the assembly of iron-sulfur clusters, essential prosthetic groups for electron transport and redox reactions. Under conditions of up-regulating miR-210 and repressing ISCU1/2, the integrity of iron-sulfur clusters appears disrupted, as assessed by electron paramagnetic resonance spectroscopy. In turn, using miRNA duplexes and miRNA antisense inhibitors, we found that miR-210 represses iron-sulfur enzyme activities controlling mitochondrial metabolism, downregulating Complex I (−27.5% ±4.5) and aconitase (−37.2% ±9.6). Consequently, miR-210 decreases oxygen consumption (−23.6% ±9.8) and modulates associated downstream functions such as ATP levels (−17% ±2.6) and reactive oxygen species flux in PAECs.
Conclusions: MiR-210 down-regulates ISCU1/2 during hypoxia to control metabolic processes that predominate in the Pasteur effect. These results identify novel mechanistic connections among microRNA, hypoxia, and mitochondrial function; and they carry broad implications for understanding the hypoxic response in the pulmonary vasculature and in disease states such as pulmonary hypertension.