title: Chromatin accessibility at a STAT3 target site is altered prior to astrocyte differentiation.
abstract: DNA demethylation of astrocyte-specific gene promoters and STAT3 activation in neural precursor cells (NPCs) are essential for astrogliogenesis in the developing brain. To date, it remains unclear whether DNA methylation is the sole epigenetic determinant responsible for suppressing astrocyte-specific genes. Here, we used mouse embryonic stem cells (TKO ESCs) that lacked all 3 DNA methyltransferase genes, Dnmt1, Dnmt3a, and Dnmt3b, and thereby exhibit complete demethylation of the astrocyte-specific glial fibrillary acidic protein (Gfap) gene promoter. We found that although the Gfap promoter was demethylated, STAT3 failed to bind to its cognate element to induce Gfap transcription, whereas it induced transcription of a different target gene, Socs3. Moreover, although the Gfap promoter region containing the STAT3-binding site (GSBS) is enriched with transcription-repressive histone modifications, such as methylation of H3 at lysine 9 (H3K9me3) and H3K27me3, the reduction of these modifications in TKO ESCs was not sufficient for binding of STAT3 at GSBS. Furthermore, GSBS was digested by micrococcal nuclease in late-gestational NPCs that express GFAP upon LIF stimulation, but not in cells that show no expression of GFAP even in the presence of LIF, indicating that STAT3 can access GSBS in the former cells. We further showed that expression of NF-1A, which is known to potentiate differentiation of mid-gestational NPCs into astrocytes, increased its accessibility. Taken together, our results suggest that chromatin accessibility of GSBS plays a critical role in the regulation of Gfap expression.
authors: Laboratory of Molecular Neuroscience, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, Japan.
authors: Satoshi
authors: S
authors: Urayama
authors: Katsunori
authors: K
authors: Semi
authors: Tsukasa
authors: T
authors: Sanosaka
authors: Yukina
authors: Y
authors: Hori
authors: Masakazu
authors: M
authors: Namihira
authors: Jun
authors: J
authors: Kohyama
authors: Takumi
authors: T
authors: Takizawa
authors: Kinichi
authors: K
authors: Nakashima
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism; D001665:Binding Sites; D002454:Cell Differentiation / Q000235:genetics*; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism; D044127:Epigenesis, Genetic; D005904:Glial Fibrillary Acidic Protein; D056484:Jumonji Domain-Containing Histone Demethylases / Q000378:metabolism; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D055495:Neurogenesis; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D011401:Promoter Regions, Genetic; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D004268:DNA-Binding Proteins; D005904:Glial Fibrillary Acidic Protein; D009419:Nerve Tissue Proteins; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; C528900:glial fibrillary astrocytic protein, mouse; D056484:Jumonji Domain-Containing Histone Demethylases; C523761:Kdm6b protein, mouse