FoxG1 is critical for postnatal hippocampal development

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Abstracts / Neuroscience Research 71S (2011) e108–e415

P2-d19 Multiple analyses of G-protein coupled receptor (GPCR) expression in the neural differentiation from embryonic stem cells Naoko Kuzumaki 1 , Michiko Narita 2 , Yusuke Hamada 2 , Atsumi Nagasawa 2 , Yohei Okada 1 , Wado Akamatsu 1 , Hirotaka J. Okano 1 , Hideyuki Okano 1 , Minoru Narita 2 1

Dept. Physiol., Keio Univ. Sch. Med. Tokyo, Japan 2 Dept. Pharmacol., Hoshi Univ. Sch. Pharm. Pharmaceut. Sci., Tokyo, Japan Embryonic stem cells (ES cells) will be valuable resources for clinical therapies because of their unlimited self-renewal ability and potential to generate any differentiated cell type. G protein coupled receptors (GPCRs) play key role in many complex biological processes, including development. However, the role of GPCRs in ES cell pluripotency and differentiation has received little attention. We demonstrated the role of GPCRs on mouse ES cells differentiation including neural or glial differentiation from neural stem cells, and pluripotency. Adrenergic receptor alpha 1a, alpha 2a and alpha 2c were upregulated with the progress of the differentiation from ES cell, whereas adrenergic receptor beta 3 (Adrb3) was dramatically decreased with the progress of the differentiation from ES cell into neural stem cells. The change in the histone modification at the promoter region of Abrb3 was seen in the neural stem cell development from ES cells. Under these conditions, a significant increase in lysine 27 on histone H3 (H3K27) trimethylation at the promoter of Adrb3 was observed in the primary neurosphere derived from ES cells. These results suggest that changes in adrenergic receptors signaling pathway along with epigenetic modification may a play a role in maintaining ES cells. doi:10.1016/j.neures.2011.07.537

P2-d20 Subregional specification of ES cell-derived ventral telencephalic tissues by timed and combinatory treatment with extrinsic signals Teruko Danjo 1 , Mototsugu Eiraku 2 , Keiko Muguruma 2 , Kiichi Watanabe 2 , Masako Kawada 2 , Yuchio Yanagawa 3 , John L.R. Rubenstein 4 , Yoshiki Sasai 2 Systems Biology, Osaka Bioscience Institute, Osaka, Japan 2 Organogenesis and Neurogenesis Group, Center for Developmental Biology, RIKEN, Kobe, Japan 3 Dept. of Genetic and Behavioral Neuroscience, Gunma Univ. Grad. School of Med., Maebashi, Japan 4 Center for Neurobiology and Psychiatry, UCSF School of Medicine, San Francisco, USA

P2-d21 FoxG1 is critical for postnatal hippocampal development Yifan Gong 1 , Chuanxi Tian 1 , Ying Yang 1 , Jing Zhao 2 , Chunjie Zhao 1 1

Institute of Life Science, Southeast University, Nanjing, P.R. China 2 MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing, P.R. China

The forkhead box G1 (FoxG1) transcription factor is strongly expressed in developing dentate gyrus (DG). Impaired DG neurogenesis and behavior in FoxG1+/− mice suggests its possible role in hippocampal development. To thoroughly study its function, we generated a FoxG1flox/flox mouse line. FoxG1 was conditionally deleted in developing DG at postnatal stages when this line was crossed with Frizzled9CreERTM line in which Cre-mediated recombination can specifically be induced by tamoxifen administration. Inactivation of FoxG1 at postnatal day 5 led to remarkable malformation of the DG, reflecting by a drastically shrinking size with a loss of lower blade, and a disrupted secondary radial glial scaffold. Detailed scrutiny revealed that FoxG1 was necessary for the maintenance of the primary progenitor (TypeI cells) pool. Being known as quiescent stem cells, these GFAP expressing Type I cells constitute the secondary radial glial scaffold and divide to produce intermediate progenitor cells (IPCs, also called Type-II cells). Our study showed that in FoxG1 conditional knockouts (cKO), Type-I cells significantly reduced and brought about a further breakup of the secondary radial glial scaffold. We also found that the neuronal lineage restricted Type-II cell population, which is characterized by Tbr2 expression, had a remarkable shrink as well. Proliferation disturbance was observed in both the Type-I and TypeII progenitor populations. Furthermore, significant cell death was detected in FoxG1 mutant developing DG, indicating FoxG1 was important for cell survival. We also found FoxG1 ablation resulted in a considerable expansion of astrocytic compartment, meanwhile, the Type-I to Type II cell transition index fell. Astonishingly, the immature neurons, derived from the Type-II progenitors, marked by calretinin expression, was enlarged in mutant mice. All these results suggested FoxG1 functioned in suppressing the differentiation of both Type-I and Type-II cell pools. doi:10.1016/j.neures.2011.07.539

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During early telencephalic development, the major portion of the ventral telencephalic (subpallial) region becomes subdivided into three regions, the lateral (LGE), medial (MGE), and caudal (CGE) ganglionic eminences. The LGE and MGE generate the striatum and the globus pallidus, respectively, which play central roles in motor control. In this study, we systematically recapitulated subpallial patterning in mouse embryonic stem cell (ESC) cultures, and investigated temporal and combinatory actions of patterning signals. In serum-free floating culture, the dorsal–ventral specification of ESC-derived telencephalic neuroectoderm is dose-dependently directed by Shh signaling. Early Shh treatment, even before the expression onset of Foxg1 (earliest marker of the telencephalic lineage), is critical for efficiently generating LGE progenitors, and continuous Shh signaling until day 9 is necessary to commit these cells to the LGE lineage. When induced under these conditions and purified by FACS, telencephalic cells efficiently differentiated into Nolz1+ /Ctip2+ LGE neuronal precursors and subsequently, both in culture and after in vivo grafting, into DARPP32+ striatal medium-sized spiny neurons. Purified telencephalic progenitors treated with high doses of the Hh agonist SAG differentiated into MGE- and CGE-like tissues. Interestingly, in addition to strong Hh signaling, the efficient specification of MGE cells requires Fgf8 signaling but is inhibited by treatment with Fgf15/19. In contrast, CGE differentiation is promoted by Fgf15/19 but suppressed by Fgf8, suggesting that specific Fgf signals play different, critical roles in the positional specification of ESC-derived ventral subpallial tissues. We discuss a model of the antagonistic Fgf8 and Fgf15/19 signaling in rostral-caudal subpallial patterning, and compare it with the roles of these molecules in cortical patterning. doi:10.1016/j.neures.2011.07.538

P2-e01 Essential function of Sbno1 in Notch signal suppression during cortical neuron differentiation Yu Katsuyama 1 , Ai Takano 2 , Naoya Ryoyama 2 , Hideaki Imai 2 , Noriko Osumi 1 , Masahiko Hibi 3 , Toshio Terashima 2 1

Div. of Dev. Neurosci., Grad. Sch. of Med., Tohoku Univ., Sendai, Japan 2 Div. of Dev. Neurosci., Grad. Sch. of Med., Kobe Univ., Sendai, Japan 3 Lab. of Organogenesis and Organ Function, Biosci. and Biotech. Center, Nagoya Univ., Japan Sbno1, a putative RNA helicase, is expressed in the developing cerebral cortex of mouse. We previously have shown that sbno1 is required for normal development of the zebrafish central nervous system, but its functional role in mouse brain development is not known. Here, we examined Sbno1 function in the neuronal differentiation employing the primary culture system in which cells were derived from E14.5 mouse embryonic cerebral cortex. Knockdown of Sbno1 by RNA interference suppressed neuronal differentiation, and Sbno1 overexpression could have an opposite effect, suggesting that Sbno1 positively regulates mouse neurogenesis. In the Sbno1 knockdown cells, some molecules, such as Hes proteins, which are regulated by Notch signal were activated. Sbno1 overexpression cancelled Notch signal activation, and Sbno1 knockdown blocked neuronal differentiation even in an inhibition of Notch signal by DAPT. These experimental results suggest that Sbno1 functions downstream of Notch. Consistent to this, RBPj, the nuclear effector protein of Notch signaling was isolated by our yeast two hybrid screening using Sbno1 as a bait. Collectively, these observations suggest that suppression of Notch signal by binding of Sbno1 to RBPj is essential for neuronal differentiation in mouse brain development. Research fund: KAKENHI (22570202). doi:10.1016/j.neures.2011.07.540