2026-06-14T03:30:17Zhttps://repisalud.isciii.es/rest/oai/request

oai:repisalud.isciii.es:20.500.12105/52532024-09-27T09:54:33Zcom_20.500.12105_19604com_20.500.12105_2051col_20.500.12105_19605

00925njm 22002777a 4500 dc Martinez-Zamora, Ana author Meseguer, Salvador author Esteve, Juan M. author Villarroya, Magda author Aguado, Carmen author Enriquez, Jose Antonio author Knecht, Erwin author Armengod, M. -Eugenia author 2015 GTPBP3 is an evolutionary conserved protein presumably involved in mitochondrial tRNA (mt-tRNA) modification. In humans, GTPBP3 mutations cause hypertrophic cardiomyopathy with lactic acidosis, and have been associated with a defect in mitochondrial translation, yet the pathomechanism remains unclear. Here we use a GTPBP3 stable-silencing model (shGTPBP3 cells) for a further characterization of the phenotype conferred by the GTPBP3 defect. We experimentally show for the first time that GTPBP3 depletion is associated with an mt-tRNA hypomodification status, as mt-tRNAs from shGTPBP3 cells were more sensitive to digestion by angiogenin than tRNAs from control cells. Despite the effect of stable silencing of GTPBP3 on global mitochondrial translation being rather mild, the steady-state levels and activity of Complex I, and cellular ATP levels were 50\% of those found in the controls. Notably, the ATPase activity of Complex V increased by about 40\% in GTPBP3 depleted cells suggesting that mitochondria consume ATP to maintain the membrane potential. Moreover, shGTPBP3 cells exhibited enhanced antioxidant capacity and a nearly 2-fold increase in the uncoupling protein UCP2 levels. Our data indicate that stable silencing of GTPBP3 triggers an AMPK-dependent retrograde signaling pathway that down-regulates the expression of the NDUFAF3 and NDUFAF4 Complex I assembly factors and the mitochondrial pyruvate carrier (MPC), while up-regulating the expression of UCP2. We also found that genes involved in glycolysis and oxidation of fatty acids are up-regulated. These data are compatible with a model in which high UCP2 levels, together with a reduction in pyruvate transport due to the down-regulation of MPC, promote a shift from pyruvate to fatty acid oxidation, and to an uncoupling of glycolysis and oxidative phosphorylation. These metabolic alterations, and the low ATP levels, may negatively affect heart function. PLoS One. 2015; 10(12):e0144273 10.1371/journal.pone.0144273 1932-6203 PLoS One 26642043 http://hdl.handle.net/20.500.12105/5253 RESPIRATORY-CHAIN DEFICIENCY FATTY-ACID OXIDATION ESCHERICHIA-COLI LACTIC-ACIDOSIS HYPERTROPHIC CARDIOMYOPATHY PHYSIOLOGICALLY RELEVANT GLUTAMINE OXIDATION H2O2 GENERATION ROS PRODUCTION CELL-SURVIVAL Defective Expression of the Mitochondrial-tRNA Modifying Enzyme GTPBP3 Triggers AMPK-Mediated Adaptive Responses Involving Complex I Assembly Factors, Uncoupling Protein 2, and the Mitochondrial Pyruvate Carrier