BMP Signaling Regulates Neural Fate Determination of Neural Precursors through Id1 and p27Xic1a in Zebrafish Brain
| Autor: | Hung Yu Shih, 石宏裕 |
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| Rok vydání: | 2009 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 BMP signalling is known to play roles in neural induction and neuronal subtype specification. However, it is not clear about its role in neural fate determination. To address this question, the expression patterns of zebrafish BMP receptor IA (zBMPR-IA) were examined by whole-mount in situ hybridization (WISH). The results showed zBMPR-IA are expressed in the central nervous system (CNS) after neural induction, suggesting BMP signalling may have functions other than neural induction. In order to further study the roles of BMP signalling in cell-fate decision, Dorsomorphin, an inhibitor of BMP signalling, was applied during gastrula period to bypass the effect of BMP signal in neural induction. Dorsomorphin-treated embryos were analyzed with neural precursor markers, Sox2 and Sox3. The results showed inhibiting BMP signalling during gastrula period did not affect the neural precursor formation. Subsequently, in order to examine whether BMP signalling involves in neural fate decision, embryos were treated with Dorsomorphin from germ ring stage to 6 somite stage. Following, the Dorsomorphin-treated embryos were examined with the neuronal progenitor marker, neurogenin1 (ngn1) and glial progenitor marker, glutamate/aspartate transporter (GLAST). The numbers of both ngn1 positive neuronal progenitors and GLAST positive glial progenitors were decreased in the brain. It implies that BMP signalling is required for neural precursors to differentiate into neuronal and glial progenitors in the brain. To gain insight of how BMP signaling pathway regulates the neural fate decision, we examined the expression of repressor-type bHLH transcriptional factor, Id1 after Dorsomorphin treatment. The results showed the Id1 expression increased after inhibiting BMP signals indicate BMP down-regulates the Id1 expression in fate–determined process. Moreover, in order to know whether BMP signaling affects the cell cycle progression, Dorsomorphin-treated embryos were examined for the expression of cyclinD1 and p27Xic1a. The results showed the cyclinD1 increased but p27Xic1a decreased, suggesting that the BMP signal controls cell cycle progression through up-regulating p27Xic1a. In addition to study the roles of BMP signaling in fate determination, we also examined the role of BMP signal in neuronal subtype specification. Dorsomorphin-treated embryos were examined by WISH and immunostaining with neuronal subtype marker, islet1/2. The islet1/2-positive cells were increased in the spinal cord after interfering BMP signalling which suggests that the BMP signal indeed involves in neuronal subtype specification. In this report, our results provide the role and regulating mechanism of BMP signaling in neural fate determination in vivo. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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