TY - JOUR T1 - Rapid degeneration of iPSC-derived motor neurons lacking Gdap1 engages a mitochondrial-sustained innate immune response. JF - Cell Death Discov Y1 - 2023 A1 - León, Marian A1 - Prieto, Javier A1 - Molina-Navarro, María Micaela A1 - Garcia-Garcia, Francisco A1 - Barneo-Muñoz, Manuela A1 - Ponsoda, Xavier A1 - Sáez, Rosana A1 - Palau, Francesc A1 - Dopazo, Joaquin A1 - Izpisua Belmonte, Juan Carlos A1 - Torres, Josema AB -

Charcot-Marie-Tooth disease is a chronic hereditary motor and sensory polyneuropathy targeting Schwann cells and/or motor neurons. Its multifactorial and polygenic origin portrays a complex clinical phenotype of the disease with a wide range of genetic inheritance patterns. The disease-associated gene GDAP1 encodes for a mitochondrial outer membrane protein. Mouse and insect models with mutations in Gdap1 have reproduced several traits of the human disease. However, the precise function in the cell types affected by the disease remains unknown. Here, we use induced-pluripotent stem cells derived from a Gdap1 knockout mouse model to better understand the molecular and cellular phenotypes of the disease caused by the loss-of-function of this gene. Gdap1-null motor neurons display a fragile cell phenotype prone to early degeneration showing (1) altered mitochondrial morphology, with an increase in the fragmentation of these organelles, (2) activation of autophagy and mitophagy, (3) abnormal metabolism, characterized by a downregulation of Hexokinase 2 and ATP5b proteins, (4) increased reactive oxygen species and elevated mitochondrial membrane potential, and (5) increased innate immune response and p38 MAP kinase activation. Our data reveals the existence of an underlying Redox-inflammatory axis fueled by altered mitochondrial metabolism in the absence of Gdap1. As this biochemical axis encompasses a wide variety of druggable targets, our results may have implications for developing therapies using combinatorial pharmacological approaches and improving therefore human welfare. A Redox-immune axis underlying motor neuron degeneration caused by the absence of Gdap1. Our results show that Gdap1 motor neurons have a fragile cellular phenotype that is prone to degeneration. Gdap1 iPSCs differentiated into motor neurons showed an altered metabolic state: decreased glycolysis and increased OXPHOS. These alterations may lead to hyperpolarization of mitochondria and increased ROS levels. Excessive amounts of ROS might be the cause of increased mitophagy, p38 activation and inflammation as a cellular response to oxidative stress. The p38 MAPK pathway and the immune response may, in turn, have feedback mechanisms, leading to the induction of apoptosis and senescence, respectively. CAC, citric acid cycle; ETC, electronic transport chain; Glc, glucose; Lac, lactate; Pyr, pyruvate.

VL - 9 IS - 1 ER - TY - JOUR T1 - Dysfunctional mitochondrial fission impairs cell reprogramming. JF - Cell Cycle Y1 - 2016 A1 - Prieto, Javier A1 - León, Marian A1 - Ponsoda, Xavier A1 - Garcia-Garcia, Francisco A1 - Bort, Roque A1 - Serna, Eva A1 - Barneo-Muñoz, Manuela A1 - Palau, Francesc A1 - Dopazo, Joaquin A1 - López-García, Carlos A1 - Torres, Josema KW - Animals KW - Cell Cycle Checkpoints KW - Cellular Reprogramming KW - DNA Damage KW - G2 Phase KW - Gene Knockdown Techniques KW - Mice KW - Mitochondrial Dynamics KW - Mitosis KW - Nerve Tissue Proteins KW - Pluripotent Stem Cells KW - Transcription Factors AB -

We have recently shown that mitochondrial fission is induced early in reprogramming in a Drp1-dependent manner; however, the identity of the factors controlling Drp1 recruitment to mitochondria was unexplored. To investigate this, we used a panel of RNAi targeting factors involved in the regulation of mitochondrial dynamics and we observed that MiD51, Gdap1 and, to a lesser extent, Mff were found to play key roles in this process. Cells derived from Gdap1-null mice were used to further explore the role of this factor in cell reprogramming. Microarray data revealed a prominent down-regulation of cell cycle pathways in Gdap1-null cells early in reprogramming and cell cycle profiling uncovered a G2/M growth arrest in Gdap1-null cells undergoing reprogramming. High-Content analysis showed that this growth arrest was DNA damage-independent. We propose that lack of efficient mitochondrial fission impairs cell reprogramming by interfering with cell cycle progression in a DNA damage-independent manner.

VL - 15 IS - 23 U1 - https://www.ncbi.nlm.nih.gov/pubmed/27753531?dopt=Abstract ER -