| Summary: | 碩士 === 慈濟大學 === 分子生物及細胞生物研究所 === 96 === Fibroblast growth factor (Fgf) signaling had been identified as the critical signaling in the liver
specification process by hsp70:dnFgfr1-EGFP transgene zebrafish. However, the critical Fgf ligands and
receptors in the processing had not been identified. Previously, we had identified Fgfr2 as the major Fgf
receptor in the endoderm at 24 hpf. In the study, we investigated that the role of Fgfr2 receptor in liver
development. We found that the FoxA3 signaling were reduced in liver but not pancreas at 48 hpf in the
Fgfr2 morphants (R2 morphants). The liver specification marker, Hhex, was also reduced or absent in R2
morphants. These results indicted that Fgfr2 played an important role in liver specification. Besides, the
candidate Fgf ligands in liver specification had been identified by RT-PCR and WISH. We screened all
zebrafish Fgfs in the development stages. The genes which expressed in the critical period were selected
to perform WISH. So far, we identified that the Fgf24 is expressed in the liver forming region at 24 hpf.
Unexpectedly, we found that the LR asymmetry was disrupted in Fgfr2 morphants. Therefore, the issue of
Fgfr2 in LR asymmetry regulation was also investigated in this study. The visceral orangs and heart were
randomized in Fgfr2 morphants. In the molecular level, Spaw, lefty1 and 2 were also randomized in
morphants. However, the notochord structure, the cilia morphology and gene exression around KV
showed no difference between WT and morphants. Further examine the gene expression in KV, the dnah9
expression was reduced in morphant but not WT. So fgfr2 may affect the left-right asymmetry at early
stage to regulate gene expression in KV. All together, we conclude that fgfr2 signaling pathway is
important in the liver specification and asymmetry regulation.
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