| Summary: | 碩士 === 慈濟大學 === 分子生物暨人類遺傳學系碩士班 === 99 === Liver regeneration is a complex process which involves regulations of various signaling pathways. Inhibition of fibroblast growth factor (Fgf) signaling specifically in hepatocytes results in delayed liver regeneration after partial hepatectomy (PH) in transgenic mouse and zebrafish. therefore, Fgf signaling is crucial for regeneration process. However, the detailed mechanisms are still unclear. In this study, we first established different PH models with various extent to analyze liver regeneration in zebrafish, namely 1/3 PH (amputation of whole ventral lobe), 2/3 PH (amputation of one ventral and one dorsal lobe) and 1/12 PH (amputation of 1/4 ventral lobe). Compensatory growth of the liver after 1/3 PH and 2/3 PH was observed, while after 1/12 PH, local growth at amputation site could be directly observed. The Tg(hsp70:dnfgfr1-EGFP) transgenic fish was heat shocked to inhibit Fgf signaling and PH was performed. We found delayed local growth of the liver after 1/12 PH, as well as decreased proliferating hepatocytes after 1/3 PH. RT-PCR results also revealed that inhibition of Fgf signaling resulted in reduced expression level of G1 phase-related genes, including cyclin D and cyclin E. However, no obvious changes in the expression of apoptosis-related genes were detected. We analyzed the expression of fgfs and fgfrs and found fgfr2c and its ligands, fgf2 and fgf4, were induced at PH3D. After Fgf signaling inhibition, the expressions of fgf2 and fgf4 were absent and fgfr2c expression was not changed before and after PH. We further analyzed for the expressions of Fgf downstream genes and found their expressions were also reduced. At last, preliminarily we found expressions of Notch signaling molecules were affected after inhibition of Fgf signaling during liver regeneration. This result indicated to us that Fgf signaling might act upstream to regulate Notch signaling. According to the above results, we suggested that Fgf signaling pathway involves in zebrafish liver regeneration mainly through regulation of hepatocyte proliferation and Fgfr2c, Fgf2 and Fgf4 might play important roles during this process.
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