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標題: | 肝再生過程中低氧環境對於肝前驅細胞形成之分子解析 The molecular mechanism of hepatic progenitor cells generation under liver injury-induced hypoxia |
作者: | Chieh-Ning Wen 文婕寧 |
指導教授: | 陳彥榮 |
關鍵字: | 肝前驅細胞,退分化,低氧,EpCAM,HIF,Wnt/β-catenin, LPC,de-differentiation,hypoxia,EpCAM,HIF,Wnt/β-catenin, |
出版年 : | 2016 |
學位: | 碩士 |
摘要: | 肝臟具有很好的再生能力,當受到損傷時會開啟其修復機制,並且會依據損傷的種類而使用不同的方式進行修復。過去研究發現慢性肝損傷之下的修復方式,會藉由肝前驅細胞的形成及擴增,以分化出新的細胞。但肝臟對於慢性肝損傷的修復機制仍然需要更深入的探討。
我們過去研究中發現四氯化碳所誘導的慢性肝損傷中,因為肝纖維化的形成,會導致肝臟內部缺氧,使得細胞表現 HIF-1α。另外也發現這些細胞會同時具有 EpCAM 與 CK19 的表現,顯示它們可能為肝前驅細胞。不過目前對於這些肝前驅細胞形成的機制以及它的細胞來源並不清楚,由於這些肝前驅細胞產生的位置在中央靜脈 (central vein) 附近,我們猜測可能是由成熟肝細胞退分化而來。 在本研究中,我想要探討低氧環境是否會使得肝細胞退分化 (dedifferentiation) 為肝前驅細胞。首先利用肝臟灌流 (liver perfusion) 的方式將小鼠的肝細胞分離出來,並培養在低氧環境之下。實驗結果顯示肝細胞在低氧環境之下,會表現肝前驅細胞的標記分子 EpCAM 與 CK19。另外,與幹細胞特性相關的分子 Sox2 與 Nanog 也有增加的現象,證實肝細胞在低氧環境之下,的確能夠被誘導退分化為肝前驅細胞。接著,實驗結果也顯示肝細胞於低氧環境之下,會開啟一個對於調控幹細胞特性相當重要的訊息傳導路徑,稱作 Wnt 訊息傳導路徑。最後也證實了 HIF-1α 可以增強 EpCAM 的轉錄活性。 綜合以上結果,低氧環境之下,HIF-1α 可以藉由開啟 Wnt 訊息傳導路徑 以及調控 EpCAM 的表現,將肝細胞「退分化」為肝前驅細胞,以幫助肝臟的再生。 Liver possesses great regeneration ability, making it enable to regenerate when encountering injury. Different regeneration models exist based on the causes of injury. In the case of chronic liver injury, liver progenitor cells (LPCs) can be activated and proliferate in order to produce new cells during regeneration. However, the mechanism of liver regeneration during chronic liver injury remains to be clarified. During CCl4-induced chronic liver injury, it was found that liver fibrosis would lead to hypoxia and some liver cells would express HIF-1α. Besides, these HIF-1α-positive cells also expressed EpCAM and CK19, suggesting that they were LPCs. However, the mechanisms of LPCs generation and their origin cells are still controversial. Since these LPCs were detected around central vein, we hypothesized that they were de-differentiated from mature hepatocytes. In this study, I investigated whether hepatocytes can de-differentiate into LPCs under hypoxia. First, primary hepatocytes were isolated from mice using liver perfusion and cultured under hypoxic conditions. Under hypoxia, primary hepatocytes expressed LPC markers such as EpCAM and CK19. Furthermore, stemness markers including Sox2 and Nanog were also elevated. Thus, hepatocytes could de-differentiate into LPCs under hypoxia. In addition, hepatocytes cultured under hypoxia could activate Wnt signaling, which is one of the essential signaling for stemness regulation. At last, I found that HIF-1α could enhance the transcription activity of EpCAM. In summary, under hypoxia, HIF-1α could activate Wnt signaling and regulate the expression of EpCAM, which might contribute to de-differentiation of hepatocytes into LPCs and promote liver regeneration. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/78138 |
DOI: | 10.6342/NTU201602268 |
全文授權: | 有償授權 |
顯示於系所單位: | 生化科技學系 |
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