Role of Sox2 in the direct lineage reprogramming of astroglia into neurons

• Applicants: Professor Dr. Benedikt Berninger; Professorin Dr. Magdalena Götz
• Subject Area: Molecular Biology and Physiology of Neurons and Glial Cells ; Cell Biology
• Term: from 2008 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 66495936

• Final Report Year: 2011

Final Report Abstract

Direct lineage conversion or reprogramming of non-neuronal cells into induced neurons may provide a novel avenue for brain repair. In this funding period of the SPP1356 we examined the molecular mechanisms underlying direct lineage reprogramming of astrocytes and other brain resident cells into neurons and started to apply knowledge obtained in our in vitro studies to the context of the injured cerebral cortex as a model for in vivo lineage conversion. Moreover, we also examined the effect of cellular maturation on reprogramming permissiveness, obtained insights into the molecular mechanisms underlying the progressive loss of permissiveness and devised strategies to overcome these restrictions. Transcriptome analysis revealed that lineage conversion of astrocytes from the postnatal cerebral cortex by the proneural factors Neurog2 and Ascl1 shares a small common transcriptional program that is required for successful reprogramming. This transcriptional core includes NeuroD4, Insm1, Prox1 and Sox11. Several of these factors play also a key role in neurogenesis in the adult dentate gyrus and olfactory bulb. Maturation of astrocytes in vitro results in the failure of Neurog2 to induce these targets, due to competition for binding with the repressor REST. Failure of inducing lineage conversion can be bypassed by direct co-expression of Neurog2-induced targets in matured astrocytes suggesting a hierarchical model according to which direct Neurog2-regulated targets may become epigenetically inaccessible while indirect targets remain accessible for some additional time. Interestingly, pericytes isolated from the adult human brain are also resistant to Ascl1-induced conversion. However, co-expression of Sox2 renders these cells permissive to reprogramming into induced neurons with GABAergic characteristics. Future studies are required to reveal whether this Sox2-induced effect involves a re-activation of epigenetically closed sites. Surprisingly, Sox2 alone can convert proliferating glial cells into immature DCX+ neuronal cells in the injured cerebral cortex in vivo. Our own work revealed the oligodendrocyte precursor cells as main target for the reprogramming activity of Sox2. This places this glial cell type into the spot light of lineage reprogramming approaches for brain repair.

Publications

• (2011) Continuous live imaging of adult neural stem cell division and lineage progression in vitro. Development 138: 1057-1068
  Costa MR, Ortega F, Brill MS, Beckervordersandforth R, Petrone C, Schroeder T, Götz M, Berninger B
  
• (2011) Generation of subtype-specific neurons from postnatal astroglia of the mouse cerebral cortex. Nat Protoc 6:214-228
  Heinrich C, Gascón S, Masserdotti G, Lepier A, Sanchez R, Simon-Ebert T, Schroeder T, Götz M, Berninger B
  
• (2011) Using an adherent cell culture of the mouse subependymal zone to study the behavior of adult neural stem cells on a single-cell level. Nat Protoc 6: 1847-1859
  Ortega F, Costa MR, Simon-Ebert T, Schroeder T, Götz M, Berninger B
  
• (2012) Reprogramming of pericyte-derived cells of the adult human brain into induced neuronal cells. Cell Stem Cell 11, 471-476
  Karow M, Sánchez R, Schichor C, Masserdotti G, Ortega F, Heinrich C, Gascón S, Khan MA, Lie DC, Dellavalle A, Cossu G, Goldbrunner R, Götz M, Berninger B
  
• (2012) Reprogramming of postnatal astroglia of the mouse neocortex into functional, synapse-forming neurons. Methods Mol Biol 814: 485-498
  Heinrich C, Götz M, Berninger B
  
• (2012) SoxC transcription factors are required for neuronal differentiation in adult hippocampal neurogenesis. J Neurosci. Feb 29, 2012; 32(9): 3067–3080
  Mu L, Berti L, Masserdotti G, Covic M, Michaelidis TM, Doberauer K, Merz K, Rehfeld F, Haslinger A, Wegner M, Sock E, Lefebvre V, Couillard-Despres S, Aigner L, Berninger B, Lie DC
  
• (2013) Live imaging of astrocyte responses to acute injury reveals selective juxtavascular proliferation. Nat Neurosci 16: 580-586
  Bardehle S, Krüger M, Buggenthin F, Schwausch J, Ninkovic J, Clevers H, Snippert HJ, Theis FJ, Meyer-Luehmann M, Bechmann I, Dimou L, Götz M
  
• (2013) Oligodendrogliogenic and neurogenic adult subependymal zone neural stem cells constitute distinct lineages and exhibit differential responsiveness to Wnt signaling. Nat Cell Biol 15: 602-613
  Ortega F, Gascón S, Masserdotti G, Deshpande A, Simon S, Fischer J, Dimou L, Lie DC, Schroeder T, Berninger B
  
• (2013) The BAF complex interacts with Pax6 in adult neural progenitors to establish a neurogenic crossregulatory transcriptional network. Cell Stem Cell 2013 13: 403-418
  Ninkovic J, Steiner-Mezzadri A, Jawerka M, Akinci U, Masserdotti G, Petricca S, Fischer J, von Holst A, Beckers J, Lie CD, Petrik D, Miller E, Tang J, Wu J, Lefebvre V, Demmers J, Eisch A, Metzger D, Crabtree G, Irmler M, Poot R, Götz M
  
• (2014) Brains in metamorphosis: reprogramming cell identity within the central nervous system. Curr Opin Neurobiol 27:208-214
  Arlotta P, Berninger B