MicroRNAs play important roles in controlling the embryonic stem cell (ESC) state. Although much is known about microRNAs maintaining ESC state, microRNAs that are responsible for promoting ESC differentiation are less reported. Here, by screening 40 microRNAs pre-selected by their expression patterns and predicted targets in Dgcr8-null ESCs, we identify 14 novel differentiation-associated microRNAs. Among them, miR-27a and miR-24, restrained by c-Myc in ESC, exert their roles of silencing self-renewal through directly targeting several important pluripotency-associated factors, such as Oct4, Foxo1 and Smads. CRISPR/Cas9-mediated knockout of all miR-27/24 in ESCs leads to serious deficiency in ESC differentiation in vitro and in vivo. Moreover, depleting of them in mouse embryonic fibroblasts can evidently promote somatic cell reprogramming. Altogether, our findings uncover the essential role of miR-27 and miR-24 in ESC differentiation and also demonstrate novel microRNAs responsible for ESC differentiation.

The developmental stage-specific expression of the human β-like globin genes has been studied for decades, and many transcriptional factors as well as other important cis elements have been identified. However, little is known about the microRNAs that potentially regulate β-like globin gene expression directly or indirectly during erythropoiesis. In this study, we show that microRNA 23a (miR-23a) and miR-27a promote β-like globin gene expression in K562 cells and primary erythroid cells through targeting of the transcription factors KLF3 and SP1. Intriguingly, miR-23a and miR-27a further enhance the transcription of β-like globin genes through repression of KLF3 and SP1 binding to the β-like globin gene locus during erythroid differentiation. Moreover, KLF3 can bind to the promoter of the miR-23a∼27a∼24-2 cluster and suppress this microRNA cluster expression. Hence, a positive feedback loop comprised of KLF3 and miR-23a promotes the expression of β-like globin genes and the miR-23a∼27a∼24-2 cluster during erythropoiesis.

目的 研究转录因子Sp1在K562细胞诱导向红系分化过程中的表达变化,并确定其对于红系分化及珠蛋白表达的影响.方法 用定量PCR及Western blot的方法确定Sp1在红系分化过程中的表达情况.通过RNAi的方法抑制Sp1的表达,并通过联苯胺染色确定K562细胞中血红蛋白的表达情况,同时定量PCR的方法分析红系分化相关基因的表达,流式细胞技术检测红系分化过程中表面标志蛋白的表达情况.结果 在hemin诱导的K562细胞以及促红细胞生成素EPO诱导的造血干细胞向红系分化过程中,Sp1的mRNA及蛋白水平均呈明显下降,提示其可能负调节红系分化过程.在K562细胞中抑制Sp1的表达则可明显提高K562细胞中的血红蛋白含量,促进γ-,ε-珠蛋白,CD71,CD235a基因的表达,同时CD71,CD235a阳性细胞比例明显增加.结论 以上结果说明转录因子Sp1负调节红系分化过程,抑制Sp1的表达可提高K562细胞中珠蛋白的表达,并促进K562细胞向红系分化.

We studied the function and mechanism of miR-24 in regulating beta-like globin gene expression. We first detected the expression of miR-24 during erythroid differentiation and also detected the globin gene expression in miR-24 overexpressing K562 cells through q-PCR. Dual-luciferase reporter assay and Western blotting were used to identify target genes of miR-24. "Rescue experiment" was further used to investigate the regulation of miR-24 on globin gene expression whether depending on targeting Sp1 or not. We found that miR-24 increased during hemin-induced K562 cells and EPO-induced HPCs (hematopoietic progenitor cells) erythroid differentiation. Overexpression of miR-24 in K562 cells promoted the epsilon- and gamma-globin gene expression during hemin-induced erythroid differentiation through targeting the negative globin regulator Sp1. These results suggested that miR-24 can improve the expression of beta-like globin gene through targeting Sp1.

Patients with diabetes tend to have an increased risk of osteoporosis that may be related to hyperglycemia. In vitro evidence has shown that high glucose can affect the proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs). Tissue regeneration depends mainly on MSCs. However, the exact mechanisms involved in high glucose-induced bone loss remain unknown. In this study, we investigated the effects of high glucose on the proliferation and osteogenic differentiation of mice bone MSCs (BMSCs) and determined the specific mechanism of bone morphogenetic protein 2 (BMP-2) in the osteogenic differentiation of mice BMSCs in a high-glucose microenvironment. High glucose (< 25 mM) promoted cell growth but suppressed mineralization. The intracellular BMP-2 level in BMSCs cultured in a high-glucose microenvironment was significantly decreased and suppressed activation of the BMP signaling pathway. Consequently, expression of the osteogenic markers Runx2, alkaline phosphatase, and osteocalcin were decreased. Meanwhile, supplementation with ectogenic BMP-2 reversed the cell osteogenic differentiation and osteogenic marker down-regulation under high glucose. Our data indicate that BMP-2 plays an important role in regulating the osteogenic differentiation of BMSCs in a high-glucose microenvironment. Thus, it is possible that agents modifying this pathway could be used by BMSCs to promote bone regeneration in high-glucose microenvironments.

BACKGROUND AIMS:Gastric cancer is the most frequent gastrointestinal tumor in adults and is the most lethal form of human cancer. Despite of the improvements in treatments, the underlying mechanism of gastric carcinogenesis is not well known. To define novel modulators that regulate susceptibility to tumorgenesis, we focused on miR-219-2-3p.METHODS:Quantitative RT-PCR was employed to investigate the level of miR-219-2-3p in gastric cancer (GC) tissues (n = 113) and their matched adjacent normal tissues (n = 113). In vitro cell proliferation, apoptosis assays, cell migration, and invasion assays were performed to elucidate biological effects of miR-219-2-3p. Since silencing of miRNA by promoter CpG island methylation may be an important mechanism in tumorgenesis, GC cells were treated with 5-aza-2'-deoxycytidine and trichostatin A, and expression changes of miR-219-2-3p were subsequently examined by quantitative RT-PCR. Finally, the methylation status of CpG island upstream of miR-219-2-3p was analyzed by methylation-specific PCR in GC tissues (n = 22).RESULTS:miR-219-2-3p was down-regulated in GC and cell lines. In addition, the experiments documented the lower expression of miR-219-2-3p in GC specimens with higher grade and later stage tumors. Meanwhile, miR-219-2-3p exerted antiproliferative, proapoptotic, and antimetastatic roles and reduced levels of p-ERK1/2 in GC cells. Furthermore, 5-aza-2'-deoxycytidine and trichostatin A increased the expression (~2 fold) of miR-219-2-3p in GC cells. By methylation-specific PCR, DNA methylation in the upstream region of miR-219-2-3p was detected in both adjacent normal tissues and cancer tissues. As expected, the methylation level was considerably higher in the miR-219-2-3p down-regulated group than up-regulated group.CONCLUSIONS:miR-219-2-3p is potentially involved in gastric cancer progression and metastasis by regulating ERK1/2-related signal pathways, which may provide a novel therapeutic strategy for treatment of gastric cancer. Methylation mechanism may be involved in modulating the expression level of miR-219-2-3p in gastric cancer.

1材料和方法 1.1材料硬件采用PC服务器,配置:CPUPIV2.4,硬盘80G,内存512M.操作系统采用Microsoft Server2003,后台数据库管理软件采用Microsoft SQL Server 2000,前台开发工具为采用Delphi7.0,用Install Shield制作应用软件.

目的比较类风湿关节炎(rheumatoid arthritis,RA)、骨关节炎(osteo arthritisk,OA)和创伤后手术(post-traumatic,PT)患者滑膜细胞产生巨噬细胞炎症蛋白1-α(MIP-1α)、MIP-1β和活化正常T细胞表达和分泌调节因子(RANTES)的差异,探讨MIP-1α在体外能否诱导RA滑膜成纤维细胞增殖反应.方法收集RA、OA和PT患者滑膜组织.采用胶原酶消化法获得滑膜细胞,采用组织块贴壁法获得滑膜成纤维细胞.滑膜细胞培养上清中MIP-1α、MIP-1β和RANTES检测采用ELISA法.滑膜成纤维细胞增殖反应采用四甲基偶氮唑盐微量酶反应比色法(MTT法).结果 RA、OA和PT患者的滑膜细胞在体外不能自发产生MIP-1α、MIP-1β和RANTES.用LPS(5μg/ml)和白介素-1α(rhIL-1α,50U/ml)刺激滑膜细胞后,RA患者滑膜细胞可产生较高的MIP-1α和RANTES,并明显多于OA和PT患者滑膜细胞产生的量,而滑膜细胞产生MIP-1β量在3种类型患者中无明显差异.MIP-1α可诱导RA滑膜成纤维细胞增殖反应,并且在一定浓度范围内(2～50ng/ml)具有浓度依赖性.结论RA滑膜细胞在体外产生MIP-1α和RANTES的量明显高于OA和PT患者,MIP-1α诱导RA滑膜成纤维细胞的增殖反应.提示MIP-1α在RA的发病机制中可能起重要作用.

自身免疫病（AD）是机体免疫系统功能失调后对自身抗原产生免疫应答反应造成的组织损伤。AD是风湿病学科中最常见的一大类疾病,目前国际上趋向于采用教育、药物和实验研究相结合的办法进行治疗。一些严重的AD,如类风湿关节炎（RA）、系统性红斑狼疮（SLE）、系统性硬化症（SSc）等，对糖皮质激素、免疫抑制剂及细胞毒药物治疗的效果有时并不令人满意,反复使用这类药物甚至可造成感染、骨髓抑制和肝肾毒性等并发症。近年来进行了自体外周血干细胞移植（APBSCT）治疗AD的探索，并取得了一些令人鼓舞的结果［1-4］。我们就此综述如下。 　　一、 APBSCT治疗AD的由来 　　1981年Korbling等［5］采用APBSCT首先治疗1例慢性髓细胞白血病患者，重建了患者的造血功能。1986年Reiffers等［6］ 为1例急性髓细胞白血病患者实施了APBSCT，并使患者存活了6个月。此后随着研究的不断深入和广泛的临床应用， APBSCT成为某些恶性血液病和实体瘤治疗的有力手段。