Identification and Successful Negotiation of a Metabolic Checkpoint in Direct Neuronal Reprogramming

• Published in: Cell stem cell Vol. 18; no. 3; pp. 396 - 409
• Main Authors: Gascón, Sergio, Murenu, Elisa, Masserdotti, Giacomo, Ortega, Felipe, Russo, Gianluca L., Petrik, David, Deshpande, Aditi, Heinrich, Christophe, Karow, Marisa, Robertson, Stephen P., Schroeder, Timm, Beckers, Johannes, Irmler, Martin, Berndt, Carsten, Angeli, José P. Friedmann, Conrad, Marcus, Berninger, Benedikt, Götz, Magdalena
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 03.03.2016
• Subjects: Animals; Cellular Reprogramming; Cellular Reprogramming Techniques; Mice; Neuroglia - cytology; Neuroglia - metabolism; Neurons - cytology; Neurons - metabolism; Oxidative Stress; Proto-Oncogene Proteins c-bcl-2 - biosynthesis; Proto-Oncogene Proteins c-bcl-2 - genetics; Transduction, Genetic
• ISSN: 1934-5909; 1875-9777
• DOI: 10.1016/j.stem.2015.12.003

Despite the widespread interest in direct neuronal reprogramming, the mechanisms underpinning fate conversion remain largely unknown. Our study revealed a critical time point after which cells either successfully convert into neurons or succumb to cell death. Co-transduction with Bcl-2 greatly improved negotiation of this critical point by faster neuronal differentiation. Surprisingly, mutants with reduced or no affinity for Bax demonstrated that Bcl-2 exerts this effect by an apoptosis-independent mechanism. Consistent with a caspase-independent role, ferroptosis inhibitors potently increased neuronal reprogramming by inhibiting lipid peroxidation occurring during fate conversion. Genome-wide expression analysis confirmed that treatments promoting neuronal reprogramming elicit an anti-oxidative stress response. Importantly, co-expression of Bcl-2 and anti-oxidative treatments leads to an unprecedented improvement in glial-to-neuron conversion after traumatic brain injury in vivo, underscoring the relevance of these pathways in cellular reprograming irrespective of cell type in vitro and in vivo. [Display omitted] •Oxidative stress is a major hurdle in converting different cell types into neurons•Ferroptosis inhibitors and antioxidants improve direct neuronal reprogramming•Bcl-2 reduces ROS and promotes direct neuronal reprogramming also in vivo•Antioxidants potently improve maturation of induced neurons in vitro and in vivo By imaging cell fate conversion over time, Gascón, Murenu, and colleagues find that high levels of oxidative stress prevent successful direct neuronal reprogramming, instead causing extensive cell death. They identify inhibitors of ferroptosis, antioxidants, and Bcl-2 as key metabolic agents in improving generation of iNs from a range of somatic cells and in vivo after brain injury.