Project description:Pro-neural transcription factors and small molecules can induce the transdifferentiation of fibroblasts into functional neurons; however, a molecular mechanism detailing the immediate-early events that catalyze this conversion has not been well defined. We previously demonstrated that NEUROG2, forskolin (F), and dorsomorphin (D) can induce functional neurons with high-efficiency. Here, we used this model to define the genetic and epigenetic events that initiate an acquisition of neuronal identity. We demonstrate that NEUROG2 is a pioneer factor, FD enhances both genome-wide NEUROG2 chromatin occupancy and H3K27 acetylation, and synergistic transcription by these factors is essential to successful reprogramming. CREB1, activated by FD, promotes neuron survival and acts with NEUROG2 to upregulate SOX4, which co-activates NEUROD1 and NEUROD4. In addition to this hierarchical function, SOX4 targets SWI/SNF subunits and SOX4 knockdown results in extensive loss of open chromatin and abolishes reprogramming. Applying these insights, adult human glioblastoma and skin fibroblast reprogramming was improved using SOX4, SMARCA4, and chromatin modifying chemicals.
Project description:Pro-neural transcription factors and small molecules can induce the transdifferentiation of fibroblasts into functional neurons; however, a molecular mechanism detailing the immediate-early events that catalyze this conversion has not been well defined. We previously demonstrated that NEUROG2, forskolin (F), and dorsomorphin (D) can induce functional neurons with high-efficiency. Here, we used this model to define the genetic and epigenetic events that initiate an acquisition of neuronal identity. We demonstrate that NEUROG2 is a pioneer factor, FD enhances both genome-wide NEUROG2 chromatin occupancy and H3K27 acetylation, and synergistic transcription by these factors is essential to successful reprogramming. CREB1, activated by FD, promotes neuron survival and acts with NEUROG2 to upregulate SOX4, which co-activates NEUROD1 and NEUROD4. In addition to this hierarchical function, SOX4 targets SWI/SNF subunits and SOX4 knockdown results in extensive loss of open chromatin and abolishes reprogramming. Applying these insights, adult human glioblastoma and skin fibroblast reprogramming was improved using SOX4, SMARCA4, and chromatin modifying chemicals.
Project description:Pro-neural transcription factors and small molecules can induce the transdifferentiation of fibroblasts into functional neurons; however, a molecular mechanism detailing the immediate-early events that catalyze this conversion has not been well defined. We previously demonstrated that NEUROG2, forskolin (F), and dorsomorphin (D) can induce functional neurons with high-efficiency. Here, we used this model to define the genetic and epigenetic events that initiate an acquisition of neuronal identity. We demonstrate that NEUROG2 is a pioneer factor, FD enhances both genome-wide NEUROG2 chromatin occupancy and H3K27 acetylation, and synergistic transcription by these factors is essential to successful reprogramming. CREB1, activated by FD, promotes neuron survival and acts with NEUROG2 to upregulate SOX4, which co-activates NEUROD1 and NEUROD4. In addition to this hierarchical function, SOX4 targets SWI/SNF subunits and SOX4 knockdown results in extensive loss of open chromatin and abolishes reprogramming. Applying these insights, adult human glioblastoma and skin fibroblast reprogramming was improved using SOX4, SMARCA4, and chromatin modifying chemicals.
Project description:Astrocyte-to-neuron conversion has developed into a promising avenue for neuronal replacement therapy. Neurons depend critically on mitochondria function and often die by ferroptosis during the conversion process. Here we examined the extent of adequate mitochondrial reprogramming by morphology and proteome analysis. While mitochondria profoundly changed their morphology during Neurogenin2 (Neurog2) – or Achaete-scute homolog 1 (Ascl1)-mediated astrocyte-to-neuron reprogramming, we found neuron-specific mitochondrial proteins, here identified in a comprehensive proteome analysis of isolated mitochondria from primary neurons and astrocytes, to be only partially and at late stages regulated during the process. To improve this, we used dCas9 technology to induce neuron-specific mitochondrial proteins early during reprogramming. This resulted not only in increased conversion efficiency, but also in faster neuronal generation. Taken together, reprogramming mitochondria in a cell type-specific manner has powerful effects on astrocyte-to-neuron conversion, suggesting mitochondria to be a driving force in this process.
Project description:Human fibroblasts can be directly converted into cholinergic neurons by Neurogenin 2 (Neurog2 or NGN2) under the treatments of small molecules. Genome-wide analysis of gene expression was performed to examine the similarity of converted neurons to samples from human brain or spinal cord.
