胰腺腺泡細(xì)胞AR42J-B13能夠轉(zhuǎn)分化為肝細(xì)胞樣的細(xì)胞,實(shí)驗(yàn)發(fā)現(xiàn)，在這種轉(zhuǎn)分化的細(xì)胞中乙肝病毒(HBV)能夠有效的復(fù)制,。
在AR42J-B13細(xì)胞轉(zhuǎn)分化為肝細(xì)胞前后，臺(tái)灣國(guó)防醫(yī)學(xué)院的研究人員使用芯片微陣列技術(shù)發(fā)現(xiàn)了miRNAs的區(qū)別性表達(dá),。
通過(guò)實(shí)時(shí)PCR以及Northern blot分析發(fā)現(xiàn),，miRNA（包括miR-21, miR-22及miR-122a）的表達(dá)得到了顯著的提高。與此相反,，miR-93和miR-130b以及許多其它的miRNAs,，在轉(zhuǎn)分化后明顯減少。
為了研究肝細(xì)胞中miR-22的潛在作用,，他們建立了能夠穩(wěn)定表達(dá)miR-22的細(xì)胞系,。隨后通過(guò)2D-DIGE, LC-MS/MS及Western blot分析，鑒定了miR-22的幾種潛在的目的基因,。
研究發(fā)現(xiàn),，在轉(zhuǎn)分化的肝細(xì)胞，miR-22可能是通過(guò)一個(gè)直接的或者是間接的機(jī)制,，抑制了胸腺旁腺素的mRNA及蛋白的表達(dá),。在胸腺旁腺素的3'UTR，通過(guò)3'UTR報(bào)告基因分析,，他們檢測(cè)了兩個(gè)由電腦預(yù)測(cè)的miR-22靶點(diǎn),。
miR-22能夠降低胸腺旁腺素蛋白的現(xiàn)象也被發(fā)現(xiàn)于人類(lèi)肝癌細(xì)胞系Huh7及HepG2。到目前為止,，即使AR42J-B13細(xì)胞被miR-22或anti-miR-22或胸腺旁腺素表達(dá)載體的轉(zhuǎn)染,，并使用或者不使用地塞米松處理，研究人員發(fā)現(xiàn)這些對(duì)幾種轉(zhuǎn)分化標(biāo)記物沒(méi)有明顯影響,。
因此,，miR-22對(duì)于轉(zhuǎn)分化作用好像既不是充分的也不是必須的。為此,，研究人員表示,，這有可能是因?yàn)楦淖兞四軌蛘T導(dǎo)細(xì)胞發(fā)生轉(zhuǎn)分化的其它的microRNAs的表達(dá)。相關(guān)論文發(fā)表在4月6日的Plos One,。（生物谷Deepblue編譯）
doi: 10.1371/journal.pone.0034116
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MicroRNA-22 Can Reduce Parathymosin Expression in Transdifferentiated Hepatocytes
Hung-Lin Chen, Jyun-Yuan Huang, Chun-Ming Chen, Tien-Hua Chu, Chiaho Shih.
Pancreatic acinar cells AR42J-B13 can transdifferentiate into hepatocyte-like cells permissive for efficient hepatitis B virus (HBV) replication.Here, we profiled miRNAs differentially expressed in AR42J-B13 cells before and after transdifferentiation to hepatocytes, using chip-based microarray.Significant increase of miRNA expression, including miR-21, miR-22, and miR-122a, was confirmed by stem-loop real-time PCR and Northern blot analyses. In contrast, miR-93, miR-130b, and a number of other miRNAs, were significantly reduced after transdifferentiation.To investigate the potential significance of miR-22 in hepatocytes, we generated cell lines stably expressing miR-22. By 2D-DIGE, LC-MS/MS, and Western blot analyses, we identified several potential target genes of miR-22, including parathymosin.In transdifferentiated hepatocytes, miR-22 can inhibit both mRNA and protein expression of parathymosin, probably through a direct and an indirect mechanism. We tested two computer predicted miR-22 target sites at the 3′ UTR of parathymosin, by the 3′ UTR reporter gene assay.Treatment with anti-miR-22 resulted in significant elevation of the reporter activity. In addition, we observed an in vivo inverse correlation between miR-22 and parathymosin mRNA in their tissue distribution in a rat model.The phenomenon that miR-22 can reduce parathymosin protein was also observed in human hepatoma cell lines Huh7 and HepG2. So far, we detected no major effect on several transdifferentiation markers when AR42J-B13 cells were transfected with miR-22, or anti-miR-22, or a parathymosin expression vector, with or without dexamethasone treatment.Therefore, miR-22 appears to be neither necessary nor sufficient for transdifferentiation. We discussed the possibility that altered expression of some other microRNAs could induce cell cycle arrest leading to transdifferentiation.
