内含子microRNA及其宿主基因的表达与功能

微小RNA(microRNAs,miRNAs)是一类具有转录后水平基因表达调控作用的非编码小分子RNA.microRNAs可参与机体发育、代谢及恶性肿瘤、心律失常等疾病的发生.近半数microRNA的编码基因位于已知编码蛋白基因的内含子中,称为"内含子microRNA",后者称为"宿主基因".由于内含子microRNA编码基因位置的特殊性,有研究者认为二者能够共同表达并发挥相似的生物学功能.它的发现不仅丰富了人们对内含子功能的认识,还有助于完善宿主基因功能的作用通路。     

MicroRNA在肿瘤发生发展和诊断中作用的研究进展

microRNA是一类由内源基因编码的长度约为18-25个核苷酸的非编码单链RNA分子,可以与靶基因mRNA的3'非编码区结合,通过降解靶m RNA或(和)抑制靶m RNA转录后翻译调节靶蛋白的生成,从而发挥其生物学作用。目前,在人体基因组内发现的microRNA已经超过2500多个,可能调节着人类1/3的基因,在维持正常干细胞功能、调控细胞增殖分化及恶性肿瘤发生过程中均起重要作用。既往的研究表明microRNA与基因之间相互调控的失衡导致肿瘤的发生。从分子水平上研究microRNA与肿瘤发生的关系,检测microRNA与肿瘤相关基因表达情况的改变,分析肿瘤组织和血清中microRNA表达量与肿瘤分型的关系,将有利于肿瘤的病因学研究,早期发现和肿瘤治疗及预后判断。本文主要就microRNA在肿瘤发生发展和诊断中作用的研究进展进行了综述。     

植物miRNA抗胁迫机理研究进展

植物microRNA（miRNA）是一类约有21个核苷酸组成的小RNA分子,属于非编码单链RNA家族。miRNA与靶mRNA互补配对结合,以抑制基因表达或切割mRNA的方式,实现基因的负调控。miRNA对植物基因表达、生长发育和抵抗胁迫等有十分重要的影响。综述了植物miRNA特点以及miRNA抗胁迫机理的最新研究进展。     

MicroRNA 与肿瘤的相关研究进展

微小RNA(microRNAs,miRNA)是一类22个核苷酸左右的非编码调控RNA。可以通过切割mRNA或者是抑制翻译两种机制,在转录后水平发挥调控生物生长发育的重要作用。目前的研究已经发现microRNA参与调控发育、细胞分化、细胞凋亡等多种生理过程。目前已证实miRNA参与肿瘤发生和进展,miRNA表达谱是肿瘤诊断和预后的指标,miRNA突变、缺失或表达水平的异常与人类肿瘤密切相关,它发挥类似于癌基因或抑癌基因的作用,参与肿瘤细胞的增殖、分化和细胞凋亡过程。本文就miRNA在肿瘤发生发展以及诊断治疗方面的研究进展作一综述。     

植物多酚通过microRNA调控脂质代谢研究进展

microRNA（简称miRNA）是长度18~25个核苷酸的非编码RNA分子,具有调控mRNA的翻译和/或稳定性的功能,从而在转录后水平调节不同基因的表达。人体内约60%编码蛋白的基因的表达受到miRNA调节,其中包括脂质代谢调控相关基因。植物多酚具有良好的生物活性,可以通过调节脂质代谢相关miRNAs,如miR-122和miR-33的表达进而发挥降血脂等活性。该文综述了miRNA调控脂质代谢相关mRNA的作用机制以及植物多酚在这一过程中的可能作用。     

microRNA与心脏疾病

microRNA是植物和动物基因组编码的小分子非编码RNA.这种高度保守、长21～25个碱基RNA分子通过与mRNA的3'非编码区结合来调控基因组表达.microRNA通过其转录后调控机制在胚胎发育、细胞增殖,细胞分化、细胞死亡及细胞凋亡中发挥调控作用.近期研究发现,microRNA的异常表达可导致心脏疾病的发生、发展.现对microRNA在心脏发育、心肌肥厚和心肌重构、心力衰竭和心律失常等过程中的作用进行综述.     

MicroRNAs研究进展

MicroRNAs是一组21-25 nt长的非编码蛋白质的短序列RNA,能通过碱基配对与mRNA分子的3′非翻译区相结合来降解mRNA或抑制靶基因的翻译。MicroRNAs的主要功能是调控基因的表达,在生物体的生长、发育及疾病发生中扮演着重要的角色。最初绝大多数microRNA都是通过大量的克隆和测序发现的,信息学只用来验证克隆的序列是否具有发夹结构,然而这些方法无法检测低丰度或组织特异性的microRNAs。目前依赖计算机的精密的microRNAs预测技术和有效的生物学鉴定技术在mi- croRNAs的识别及其功能的阐明方面起着极其重要的作用。本文主要对microRNAs的生物信息学预测及鉴定技术进行综述。     

microRNAs在肌肉中的作用研究进展

microRNAs是一类非蛋白质编码小RNA,通常作用于靶基因mRNA的3′-UTR区引起靶基因的翻译抑制或降解。microRNAs的表达具有组织特异性,骨骼肌和心肌中有特异microRNAs的表达。microRNAs在肌肉的增殖、分化等发育过程中发挥重要的调节作用,并且microRNAs的表达异常与某些肌肉疾病的病理过程有关。现就microRNAs在肌肉中的作用研究进展作一综述。     

miRNA在肝细胞癌中的研究进展和展望

微小RNA(microRNA, miRNA)是一类长度为二十几个核苷酸的内源性非编码调控RNA,通过序列特异性翻译抑制或mRNA裂解来调控基因表达,参与细胞发育、增殖、分化、凋亡等一系列重要生物学进程。近期的研究发现,miRNA具有癌基因和抑癌基因的作用,在肿瘤的发生和发展中起着重要的作用。已发现若干miRNA直接参与肝细胞癌的发生和发展,miRNA表达谱与肝细胞癌的诊断、分期、进展和预后等相关。作为一类新的分子靶标,miRNA应用于肝细胞癌的诊断和生物治疗具有广阔的前景。     

辐射相关microRNA研究进展

microRNA(miRNA)是一类由内源基因编码的长度约22核苷酸的非编码单链RNA分子,主要以碱基互补方式与靶基因mRNA的3'非翻译区特异性结合,通过降解mRNA或抑制蛋白翻译合成而实现对靶基因的转录后调控。研究发现,miRNA在电离辐射诱导的生物学反应中发挥重要作用。我们从以下层面概述辐射相关miRNA的研究进展,即辐射调节miRNA表达、miRNA对辐射后DNA损伤的调节、miRNA参与的辐射生物学效应。     

MiR-486 Regulates Lactation and Targets the PTEN Gene in Cow Mammary Glands

Mammary gland development is controlled by several genes. Although miRNAs have been implicated in mammary gland function, the mechanism by which miR-486 regulates mammary gland development and lactation remains unclear. We investigated miR-486 expression in cow mammary gland using qRT-PCR and ISH and show that miR-486 expression was higher during the high-quality lactation period. We found that miR-486 targets phosphoinositide signaling in the cow mammary gland by directly downregulating PTEN gene expression and by altering the expression of downstream genes that are important for the function of the mammary gland, such as AKT, mTOR. We analyzed the effect of β-casein, lactose and triglyceride secretion in bovine mammary gland epithelial cells (BMECs) transfected by an inhibitor and by mimics of miR-486. Our results identify miR-486 as a downstream regulator of PTEN that is required for the development of the cow mammary gland.     

Overexpression of miR-30b in the Developing Mouse Mammary Gland Causes a Lactation Defect and Delays Involution

Background

MicroRNA (miRNA) are negative regulators of gene expression, capable of exerting pronounced influences upon the translation and stability of mRNA. They are potential regulators of normal mammary gland development and of the maintenance of mammary epithelial progenitor cells. This study was undertaken to determine the role of miR-30b on the establishment of a functional mouse mammary gland. miR-30b is a member of the miR-30 family, composed of 6 miRNA that are highly conserved in vertebrates. It has been suggested to play a role in the differentiation of several cell types.

Methodology/Principal Findings

The expression of miR-30b was found to be regulated during mammary gland development. Transgenic mice overexpressing miR-30b in mammary epithelial cells were used to investigate its role. During lactation, mammary histological analysis of the transgenic mice showed a reduction in the size of alveolar lumen, a defect of the lipid droplets and a growth defect of pups fed by transgenic females. Moreover some mammary epithelial differentiated structures persisted during involution, suggesting a delay in the process. The genes whose expression was affected by the overexpression of miR-30b were characterized by microarray analysis.

Conclusion/Significance

Our data suggests that miR-30b is important for the biology of the mammary gland and demonstrates that the deregulation of only one miRNA could affect lactation and involution.     

miR-27a suppresses triglyceride accumulation and affects gene mRNA expression associated with fat metabolism in dairy goat mammary gland epithelial cells

MicroRNAs (miRNAs), a well-defined group of small RNAs containing about 22 nucleotides, participate in various biological metabolic processes. miR-27a is a miRNA that is known to regulate fat synthesis and differentiation in preadipocyte cells. However, little is known regarding the role that miR-27a plays in regulating goat milk fat synthesis. In this study, we determined the miR-27a expression profile in goat mammary gland and found that miR-27a expression was correlated with the lactation cycle. Additionally, prolactin promoted miR-27a expression in goat mammary gland epithelial cells. Further functional analysis showed that over-expression of miR-27a down-regulated triglyceride accumulation and decreased the ratio of unsaturated/saturated fatty acid in mammary gland epithelial cells. miR-27a also significantly affected mRNA expression related to milk fat metabolism. Specifically, over-expression of miR-27a reduced gene mRNA expression associated with triglyceride synthesis by suppressing PPARγ protein levels. This study provides the first experimental evidence that miR-27a regulates triglyceride synthesis in goat mammary gland epithelial cells and improves our understanding about the importance of miRNAs in milk fat synthesis.     

Identification and characterization of microRNAs from the bovine adipose tissue and mammary gland

We report the identification of bovine miRNAs by cloning small RNAs from adipose tissue and the mammary gland. Fifty-nine distinct miRNAs were identified, five of them were not homologous to known mammalian miRNAs, and many of them had 3' and/or 5' end variants. Ribonuclease protection assays indicated that miR-23a and miR-24, whose genes are closely located on the same chromosome, were co-expressed in different tissues. The assays also suggested a role for several miRNAs in the mammary gland and a role for miR-133, a previously known skeletal and cardiac muscle-specific miRNA, in the rumen, an organ unique to the ruminant.