【摘要】：人骨髓來源的間充質(zhì)干細(xì)胞(MSCs)是一種具有多向分化能力的干細(xì)胞,在一些分化因子的調(diào)控下能分化成多種細(xì)胞,如成脂細(xì)胞、成骨細(xì)胞、成軟骨細(xì)胞等。所以,MSCs作為成骨細(xì)胞的前體細(xì)胞,對于骨的形成和重建具有重要的意義。 microRNA(miRNA)是由20 ~ 24個(gè)核苷酸組成的非編碼小RNA,可以通過與靶標(biāo)基因mRNA 3’-UTR上的靶點(diǎn)結(jié)合,介導(dǎo)mRNA降解或抑制mRNA轉(zhuǎn)錄后水平的表達(dá),從而導(dǎo)致靶標(biāo)蛋白表達(dá)的下降。近十年來的研究發(fā)現(xiàn)miRNA在胚胎發(fā)育及細(xì)胞的增殖、分化和凋亡等多種生命活動(dòng)中發(fā)揮著重要作用。但是,miRNA是否調(diào)控MSCs成骨分化的命運(yùn)卻一直未見報(bào)道。 我們在研究中發(fā)現(xiàn),miR-17-5p家族,尤其是miR-20a,能決定人MSCs成骨分化的命運(yùn)和調(diào)控成骨分化的過程。miR-20a mimics的過表達(dá)能促進(jìn)Runx2和BMPs在轉(zhuǎn)錄和翻譯水平的表達(dá)升高,從而激活BMP信號(hào)通路。我們通過軟件預(yù)測和分析,發(fā)現(xiàn)PPARγ是miR-20a的一個(gè)靶標(biāo)基因。miR-20a能通過抑制PPARγ表達(dá)來上調(diào)Runx2和BMPs的表達(dá),從而破壞成脂分化與成骨分化的動(dòng)態(tài)平衡,決定MSCs成骨分化的命運(yùn)。軟件的預(yù)測還提示BAMBI和CRIM1也是它的靶標(biāo)基因。其中BAMBI是BMP的一個(gè)假受體,與真受體競爭性的與BMP蛋白結(jié)合,從而拮抗BMP信號(hào)通路。而CRIM1是BMP信號(hào)通路的抑制子,能阻斷BMP蛋白的成熟和向細(xì)胞膜的轉(zhuǎn)移。所以,miR-20a通過抑制這兩個(gè)基因的表達(dá)從而上調(diào)了BMP信號(hào)通路,而BMP信號(hào)的激活又加速了成骨分化�？傊�,本論文研究發(fā)現(xiàn)miR-20a通過調(diào)控靶標(biāo)基因PPARγ的表達(dá)決定了MSCs成骨分化的命運(yùn),又通過對另外兩個(gè)靶標(biāo)基因BAMBI和CRIM1的表達(dá)抑制從而上調(diào)了BMP/Runx2信號(hào)通路。
[Abstract]:Human bone marrow-derived mesenchymal stem cells (MSCs) are multidirectional stem cells, which can differentiate into many kinds of cells under the control of some differentiation factors, such as adipoblast, osteoblast, chondroblast and so on. As a precursor of osteoblasts, MSCs are important for bone formation and reconstruction. MicroRNA (miRNA) is a small non-coding RNAs composed of 20 ~ 24 nucleotides, which can be combined with target sites of target gene mRNA 3nc-UTR. It mediates mRNA degradation or inhibits the expression of mRNA posttranscriptional level, which leads to the decrease of target protein expression. In recent ten years, miRNA has been found to play an important role in embryonic development, cell proliferation, differentiation and apoptosis. However, whether miRNA regulates the osteogenic differentiation of MSCs has not been reported. We found that miR-17-5p family, especially miR-20a, can determine the fate of osteogenic differentiation of human MSCs and regulate the process of osteogenic differentiation. The overexpression of miR-20a mimics can promote the expression of Runx2 and BMPs at transcription and translation level, thus activating the BMPsignaling pathway. Through software prediction and analysis, we found that PPAR 緯 is a target gene of miR-20a. MiR-20a can up-regulate the expression of Runx2 and BMPs by inhibiting the expression of PPAR 緯, thus disrupting the dynamic balance between adipogenic and osteogenic differentiation and determining the fate of osteogenic differentiation of MSCs. Software predictions also suggest that BAMBI and CRIM1 are also its target genes. Among them, BAMBI is a pseudoreceptor of BMP, which binds to BMP protein competitively with true receptor, thus antagonizing BMP signaling pathway. CRIM1 is an inhibitor of BMP signaling pathway, which can block the maturation of BMP protein and its transfer to cell membrane. Therefore, miR-20a upregulated the BMP signaling pathway by inhibiting the expression of these two genes, and the activation of BMP signal accelerated osteogenic differentiation. In conclusion, we found that miR-20a determines the osteogenic differentiation of MSCs by regulating the expression of target gene PPAR 緯, and up-regulates the BMPP Runx2 signaling pathway by inhibiting the expression of other two target genes BAMBI and CRIM1.
【學(xué)位授予單位】：清華大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2010
【分類號(hào)】：R329

【引證文獻(xiàn)】

相關(guān)碩士學(xué)位論文 前1條

1 郭杰;MicroRNA-370在高頻脈沖電磁場下對骨髓間充質(zhì)干細(xì)胞增值調(diào)控作用的初步研究[D];廣西醫(yī)科大學(xué);2013年

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本文編號(hào)：2123949