新浪登录
腾讯登录哈医大揭示rDNA活性影响克隆胚胎早期发育机制
| 导读 | 近日，哈尔滨医科大学基础医学院组胚教研室科研人员最新研究发现，体细胞中rDNA（核糖体DNA）的活性与克隆胚胎早期胚胎发育过程中的核仁活性和功能之间联系密切，这一发现为重编程机理的研究提供了新的视角和切入点。相关论文在线发表于《生物化学期刊》（<em>Journal of Biological Chemistry</em>）。
<!--more-->
... |
近日，哈尔滨医科大学基础医学院组胚教研室科研人员最新研究发现，体细胞中rDNA（核糖体DNA）的活性与克隆胚胎早期胚胎发育过程中的核仁活性和功能之间联系密切，这一发现为重编程机理的研究提供了新的视角和切入点。相关论文在线发表于《生物化学期刊》（<em>Journal of Biological Chemistry</em>）。
<!--more-->
细胞的生长和增殖依赖足够的核糖体以维持蛋白质合成。目前体细胞克隆效率很低，重编程过程能否开启沉默的rDNA转录，从而产生充足的rRNA以保障核糖体和蛋白的合成，可能与开启发育关键基因的转录同样重要。
哈医大基础医学院组胚教研室教授雷蕾带领博士研究生郑重等人员，从核糖体基因的表观修饰出发，研究分化的体细胞中，rDNA的活性对克隆胚胎早期发育过程中rDNA重新激活的影响。
他们的实验表明，小鼠胚胎干细胞、颗粒细胞和成纤维细胞的rDNA甲基化水平分别为6.67%、13.59%和22.57%，呈递增趋势。与之对应，银染显示活性核仁组织区（NORs）数目分别为7.66、6.45和4.70，呈递减趋势，且荧光实时定量PCR显示胚胎干细胞的rRNA合成和加工水平要高于另两种细胞。
专家认为，这项研究首次证明了体细胞中rDNA的活性与克隆胚胎早期胚胎发育过程中的核仁活性和功能之间的密切联系，为重编程机理的研究提供了新的视角和切入点。同时，由于rDNA的活性与细胞增殖、衰老、分化等密切相关，这一成果也为深入探讨延缓细胞衰老、核糖体病变及肿瘤的发生与治疗奠定了基础。
<br/><strong>原文摘要：</strong><br/>
<br/><strong>rRNA genes are not fully activated in mouse somatic cell nuclear transfer embryos</strong><br/>
Zhong Zheng1, Jia-lin Jia1, Gerelchimeg Bou2, Li-Li Hu1, Zhen-Dong Wang1, Xing-Hui Shen1, Zhi-Yan Shan1, Jing-Ling Shen1, Zhong-Hua Liu2 and Lei Lei
The well-known and most important function of nucleoli is ribosome biogenesis. However, the nucleolus showed delayed development and malfunction in somatic cell nuclear transfer (NT) embryos. Previous studies indicated that nearly half rRNA genes (rDNA) in somatic cells were inactive and not transcribed. We compared the rDNA methylation level, active nucleolar organizer regions (NORs) numbers, nucleolar proteins (upstream binding factor/UBF, nucleophosmin/B23) distribution and nucleolar related gene expression in three different donor cells and NT embryos. The results showed embryonic stem cells (ESCs) had the most active NORs and lowest rDNA methylation level (7.66 and 6.76%) while mouse embryonic fibroblasts (MEFs) were the opposite (4.70 and 22.57%). After the donor cells were injected into enucleated MII oocytes, cumulus cells (CCs) and MEFs nuclei lost B23 and UBF signals in 20min, while in ESC-NT embryos, B23 and UBF signals could still be detected at 60min post NT. The embryos derived from ESCs, CCs, and MEFs showed the same trend in active NORs numbers (7.19 vs. 6.68 vs. 5.77, P<0.05) and rDNA methylation level (6.36% vs. 9.67% vs. 15.52%) at 4-cell stage as that in donor cells. However, the MEF-NT embryos displayed low rRNA synthesis/processing potential at morula stage and had an obvious decrease in blastocyst developmental rate. The results presented clear evidences that the rDNA reprogramming efficiency in NT embryos was determined by the rDNA activity in donor cells from which they derived.
<!--more-->
细胞的生长和增殖依赖足够的核糖体以维持蛋白质合成。目前体细胞克隆效率很低，重编程过程能否开启沉默的rDNA转录，从而产生充足的rRNA以保障核糖体和蛋白的合成，可能与开启发育关键基因的转录同样重要。
哈医大基础医学院组胚教研室教授雷蕾带领博士研究生郑重等人员，从核糖体基因的表观修饰出发，研究分化的体细胞中，rDNA的活性对克隆胚胎早期发育过程中rDNA重新激活的影响。
他们的实验表明，小鼠胚胎干细胞、颗粒细胞和成纤维细胞的rDNA甲基化水平分别为6.67%、13.59%和22.57%，呈递增趋势。与之对应，银染显示活性核仁组织区（NORs）数目分别为7.66、6.45和4.70，呈递减趋势，且荧光实时定量PCR显示胚胎干细胞的rRNA合成和加工水平要高于另两种细胞。
专家认为，这项研究首次证明了体细胞中rDNA的活性与克隆胚胎早期胚胎发育过程中的核仁活性和功能之间的密切联系，为重编程机理的研究提供了新的视角和切入点。同时，由于rDNA的活性与细胞增殖、衰老、分化等密切相关，这一成果也为深入探讨延缓细胞衰老、核糖体病变及肿瘤的发生与治疗奠定了基础。
<br/><strong>原文摘要：</strong><br/>
<br/><strong>rRNA genes are not fully activated in mouse somatic cell nuclear transfer embryos</strong><br/>
Zhong Zheng1, Jia-lin Jia1, Gerelchimeg Bou2, Li-Li Hu1, Zhen-Dong Wang1, Xing-Hui Shen1, Zhi-Yan Shan1, Jing-Ling Shen1, Zhong-Hua Liu2 and Lei Lei
The well-known and most important function of nucleoli is ribosome biogenesis. However, the nucleolus showed delayed development and malfunction in somatic cell nuclear transfer (NT) embryos. Previous studies indicated that nearly half rRNA genes (rDNA) in somatic cells were inactive and not transcribed. We compared the rDNA methylation level, active nucleolar organizer regions (NORs) numbers, nucleolar proteins (upstream binding factor/UBF, nucleophosmin/B23) distribution and nucleolar related gene expression in three different donor cells and NT embryos. The results showed embryonic stem cells (ESCs) had the most active NORs and lowest rDNA methylation level (7.66 and 6.76%) while mouse embryonic fibroblasts (MEFs) were the opposite (4.70 and 22.57%). After the donor cells were injected into enucleated MII oocytes, cumulus cells (CCs) and MEFs nuclei lost B23 and UBF signals in 20min, while in ESC-NT embryos, B23 and UBF signals could still be detected at 60min post NT. The embryos derived from ESCs, CCs, and MEFs showed the same trend in active NORs numbers (7.19 vs. 6.68 vs. 5.77, P<0.05) and rDNA methylation level (6.36% vs. 9.67% vs. 15.52%) at 4-cell stage as that in donor cells. However, the MEF-NT embryos displayed low rRNA synthesis/processing potential at morula stage and had an obvious decrease in blastocyst developmental rate. The results presented clear evidences that the rDNA reprogramming efficiency in NT embryos was determined by the rDNA activity in donor cells from which they derived.
还没有人评论，赶快抢个沙发