OLIG2 is an in vivo bookmarking transcription factor in the developing neural tube in mouse

• Published in: Journal of neurochemistry 2023-05, Vol.165 (3), p.303-317
• Main Authors: Hayashi, Shinichi, Oe, Souichi, Koike, Taro, Seki‐Omura, Ryohei, Nakano, Yosuke, Hirahara, Yukie, Tanaka, Susumu, Ito, Takeshi, Yasukochi, Yoshiki, Higasa, Koichiro, Kitada, Masaaki
• Format: Article
• Language: English
• Subjects: Animals; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic Helix-Loop-Helix Transcription Factors - metabolism; bookmarking; Cell cycle; Cell Differentiation - genetics; Cell fate; cellular memory; Chromatin; Chromosomes; Deletion mutant; Deoxyribonucleic acid; DNA; DNA methylation; Embryos; Epigenesis, Genetic; Epigenetics; Gene expression; Helix-loop-helix proteins (basic); Histone H3; Histones; Localization; Mice; Motor neurons; Nerve Tissue Proteins - metabolism; Neural stem cells; Neural tube; Neural Tube - metabolism; OLIG2; Olig2 protein; oligodendrocyte; Oligodendrocyte Transcription Factor 2 - genetics; Oligodendrocyte Transcription Factor 2 - metabolism; Oligodendrocytes; Oligodendroglia - metabolism; Phosphorylation; Photobleaching; pMN; Progenitor cells; Transcription factors; Transcription Factors - genetics; transcriptional regulation
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/jnc.15746

Cells possess intrinsic features that are inheritable via epigenetic regulation, such as DNA methylation and histone modification. These inheritable features maintain a unique gene expression pattern, underlying cellular memory. Because of the degradation or displacement of mitotic chromosomes, most transcription factors do not contribute to cellular memory. However, accumulating in vitro evidence indicates that some transcription factors can be retained in mitotic chromosomes called as bookmarking. Such transcription factors may contribute to a novel third mechanism of cellular memory. Since most findings of transcription factor bookmarking have been reported in vitro, little is currently known in vivo. In the neural tube of mouse embryos, we discovered that OLIG2, a basic helix loop helix (bHLH) transcription factor that regulates proliferation of neural progenitors and the cell fate of motoneurons and oligodendrocytes, binds to chromatin through every cell cycle including M‐phase. OLIG2 chromosomal localization coincides with mitotic cell features such as the phosphorylation of histone H3, KI67, and nuclear membrane breakdown. Chromosomal localization of OLIG2 is regulated by an N‐terminus triple serine motif. Photobleaching analysis revealed slow OLIG2 mobility, suggesting a high affinity of OLIG2 to DNA. In Olig2 N‐terminal deletion mutant mice, motoneurons and oligodendrocyte progenitor numbers are reduced in the neural tube, suggesting that the bookmarking regulatory domain is important for OLIG2 function. We conclude that OLIG2 is a de novo in vivo bookmarking transcription factor. Our results demonstrate the presence of in vivo bookmarking in a living organism and illustrate a novel function of transcription factors. Cells possess intrinsic features that are inheritable via epigenetic regulation, such as DNA methylation and histone modification. Bookmarking transcription factors can be retained in mitotic chromosomes and would contribute to a novel third mechanism of cellular memory. Here, we report that OLIG2, a basic helix loop helix (bHLH) transcription factor that regulates the proliferation of neural progenitors and the cell fate of motoneurons and oligodendrocytes, is retained in the chromatin during mitosis in the neural tube of mouse embryos. Our results demonstrate the presence of in vivo bookmarking in a living organism and illustrate the novel function of transcription factors.