| Autor: |
Elsen GE; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States., Bedogni F; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States., Hodge RD; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States., Bammler TK; Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, United States., MacDonald JW; Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, United States., Lindtner S; Nina Ireland Laboratory of Developmental Neurobiology, University of California, San Francisco, San Francisco, CA, United States.; Department of Psychiatry, University of California, San Francisco, San Francisco, CA, United States., Rubenstein JLR; Nina Ireland Laboratory of Developmental Neurobiology, University of California, San Francisco, San Francisco, CA, United States.; Department of Psychiatry, University of California, San Francisco, San Francisco, CA, United States., Hevner RF; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States.; Department of Neurological Surgery, School of Medicine, University of Washington, Seattle, WA, United States. |
| Abstrakt: |
Epigenetic factors (EFs) regulate multiple aspects of cerebral cortex development, including proliferation, differentiation, laminar fate, and regional identity. The same neurodevelopmental processes are also regulated by transcription factors (TFs), notably the Pax6→ Tbr2→ Tbr1 cascade expressed sequentially in radial glial progenitors (RGPs), intermediate progenitors, and postmitotic projection neurons, respectively. Here, we studied the EF landscape and its regulation in embryonic mouse neocortex. Microarray and in situ hybridization assays revealed that many EF genes are expressed in specific cortical cell types, such as intermediate progenitors, or in rostrocaudal gradients. Furthermore, many EF genes are directly bound and transcriptionally regulated by Pax6, Tbr2, or Tbr1, as determined by chromatin immunoprecipitation-sequencing and gene expression analysis of TF mutant cortices. Our analysis demonstrated that Pax6, Tbr2, and Tbr1 form a direct feedforward genetic cascade, with direct feedback repression. Results also revealed that each TF regulates multiple EF genes that control DNA methylation, histone marks, chromatin remodeling, and non-coding RNA. For example, Tbr1 activates Rybp and Auts2 to promote the formation of non-canonical Polycomb repressive complex 1 (PRC1). Also, Pax6, Tbr2, and Tbr1 collectively drive massive changes in the subunit isoform composition of BAF chromatin remodeling complexes during differentiation: for example, a novel switch from Bcl7c (Baf40c) to Bcl7a (Baf40a), the latter directly activated by Tbr2. Of 11 subunits predominantly in neuronal BAF, 7 were transcriptionally activated by Pax6, Tbr2, or Tbr1. Using EFs, Pax6→ Tbr2→ Tbr1 effect persistent changes of gene expression in cell lineages, to propagate features such as regional and laminar identity from progenitors to neurons. |
