Specificity of microRNA target selection in translational repression

MicroRNAs (miRNAs) are a class of noncoding RNAs found in organisms as evolutionarily distant as plants and mammals, yet most of the mRNAs they regulate are unknown. Here we show that the ability of an miRNA to translationally repress a target mRNA is largely dictated by the free energy of binding of the first eight nucleotides in the 5' region of the miRNA. However, G:U wobble base-pairing in this region interferes with activity beyond that predicted on the basis of thermodynamic stability. Furthermore, an mRNA can be simultaneously repressed by more than one miRNA species. The level of repression achieved is dependent on both the amount of mRNA and the amount of available miRNA complexes. Thus, predicted miRNA:mRNA interactions must be viewed in the context of other potential interactions and cellular conditions.     

Human Milk Exosomal MicroRNA: Associations with Maternal Overweight/Obesity and Infant Body Composition at 1 Month of Life

Among all the body fluids, breast milk is one of the richest sources of microRNAs (miRNAs). MiRNAs packaged within the milk exosomes are bioavailable to breastfeeding infants. The role of miRNAs in determining infant growth and the impact of maternal overweight/obesity on human milk (HM) miRNAs is poorly understood. The objectives of this study were to examine the impact of maternal overweight/obesity on select miRNAs (miR-148a, miR-30b, miR-29a, miR-29b, miR-let-7a and miR-32) involved in adipogenesis and glucose metabolism and to examine the relationship of these miRNAs with measures of infant body composition in the first 6 months of life. Milk samples were collected from a cohort of 60 mothers (30 normal-weight [NW] and 30 overweight [OW]/obese [OB]) at 1-month and a subset of 48 of these at 3 months of lactation. Relative abundance of miRNA was determined using real-time PCR. The associations between the miRNAs of interest and infant weight and body composition at one, three, and six months were examined after adjusting for infant gestational age, birth weight, and sex. The abundance of miR-148a and miR-30b was lower by 30% and 42%, respectively, in the OW/OB group than in the NW group at 1 month. miR-148a was negatively associated with infant weight, fat mass, and fat free mass, while miR-30b was positively associated with infant weight, percent body fat, and fat mass at 1 month. Maternal obesity is negatively associated with the content of select miRNAs in human milk. An association of specific miRNAs with infant body composition was observed during the first month of life, suggesting a potential role in the infant’s adaptation to enteral nutrition.     

Carbamazepine-induced sperm disorders can be associated with the altered expressions of testicular KCNJ11/miR-let-7a and spermatozoal CFTR/miR-27a

Male infertility is a global health problem, and the underlying molecular mechanisms are not clearly known. Ion channels and microRNAs (miRNAs), known to function in many vital functions in cells, have been shown to play a significant role in male infertility through changes in their expressions. The study aimed to evaluate the alterations of testicular and/or spermatozoal potassium voltage-gated channel subfamily J member 11 (KCNJ11), Cystic fibrosis transmembrane conductance regulator (CFTR), miR-let-7a and miR-27a expressions in carbamazepine-related male infertility. Here, we showed that carbamazepine reduced sperm motility, increased abnormal sperm morphology, and impaired hormonal balance as well as increased relative testis weight and decreased relative seminal vesicle weight. On the other hand, downregulated KCNJ11 and upregulated miR-let-7a expressions were determined in testis (p < .05). Also, downregulated KCNJ11 and upregulated CFTR and miR-27a expressions were found in spermatozoa (p < .05). Interestingly, altered testicular KCNJ11 and miR-let-7a expressions were correlated with decreased sperm motility and elevated sperm tail defect. Besides, spermatozoal CFTR and miR-27a expressions positively correlated with sperm tail defects. The results indicated a significant relationship between ion channel and/or miRNA expression alterations and impaired sperm parameters due to carbamazepine usage.     

Endothelial-Derived miR-17∼92 Promotes Angiogenesis to Protect against Renal Ischemia-Reperfusion Injury

BackgroundDamage to the renal microvasculature is a hallmark of renal ischemia-reperfusion injury (IRI)–mediated AKI. The miR-17∼92 miRNA cluster (encoding miR-17, -18a, -19a, -20a, -19b-1, and -92a-1) regulates angiogenesis in multiple settings, but no definitive role in renal endothelium during AKI pathogenesis has been established.MethodsAntibodies bound to magnetic beads were utilized to selectively enrich for renal endothelial cells from mice. Endothelial-specific miR-17∼92 knockout (miR-17∼92^endo−/−) mice were generated and given renal IRI. Mice were monitored for the development of AKI using serum chemistries and histology and for renal blood flow using magnetic resonance imaging (MRI) and laser Doppler imaging. Mice were treated with miRNA mimics during renal IRI, and therapeutic efficacies were evaluated.ResultsmiR-17, -18a, -20a, -19b, and pri–miR-17∼92 are dynamically regulated in renal endothelial cells after renal IRI. miR-17∼92^endo−/− exacerbates renal IRI in male and female mice. Specifically, miR-17∼92^endo−/− promotes renal tubular injury, reduces renal blood flow, promotes microvascular rarefaction, increases renal oxidative stress, and promotes macrophage infiltration to injured kidneys. The potent antiangiogenic factor thrombospondin 1 (TSP1) is highly expressed in renal endothelium in miR-17∼92^endo−/− after renal IRI and is a target of miR-18a and miR-19a/b. miR-17∼92 is critical in the angiogenic response after renal IRI, which treatment with miR-18a and miR-19b mimics can mitigate.ConclusionsThese data suggest that endothelial-derived miR-17∼92 stimulates a reparative response in damaged renal vasculature during renal IRI by regulating angiogenic pathways.     

微RNA在肿瘤研究中的意义

微RNA（microRNA;miRNA）,又名小分子RNA,是序列特异转录后抑制基因表达的调节因子,是一种长约19～25nt广泛存在于真核细胞胞质内的单链小分子RNA,是一组不编码蛋白质的短序列RNA,它本身不具有开放阅读框（ORF）;成熟的miRNA 5′端有一个磷酸基团,3′端为羟基.miRNA参与生命过程中一系列的重要进程,包括个体发育、造血生成、器官形成、细胞凋亡、细胞增殖与分化、脂肪代谢,甚至肿瘤发生.为更全面地认识miRNA,特别是miRNA在肿瘤诊治中的意义,本文将从以下几个方面对miRNA的研究做一介绍.     

力学刺激通过microRNA调控骨重建的研究进展

骨骼结构完整性和骨量的维持需要一定的力学刺激。研究表明,力学刺激可通过调控多种调节因子(例如激素、转录因子和信号分子等)参与骨重建过程。力学刺激可以通过调控微小RNA(microRNA,miRNA)表达在骨重建过程中起着至关重要的作用。然而,受力学刺激调控的miRNA在骨重建过程中的作用和机制尚不完全清楚。本文综述受力学刺激调控的miRNA在骨重建过程中的作用及其机制,并强调其在治疗骨质疏松中的潜在应用。     

土龙祛疣洗剂对尖锐湿疣皮损microRNA表达的影响

目的:探讨土龙祛疣洗剂对尖锐湿疣(CA)皮损标本中micro RNA分子表达谱的影响。方法:以39例CA患者为观察组,使用土龙祛疣洗剂熏洗治疗,6周后观察疗效。以同期自本院外科就诊的10例行包皮环切患者为对照组,取其正常包皮组织。采用q RT-PCR检测2组5个炎症相关micro RNA(mi R-21、mi R-203、mi R-125b、mi R-146a和mi R-155)的表达情况。结果:39例CA患者治疗6周后27例皮损消退明显,症状减轻,总有效率为69.2%;观察组mi R-203与正常对照组相比呈现低表达,土龙祛疣洗剂治疗后呈现明显上调,差异有统计学意义(P0.01);mi R-21治疗后表达量与治疗前相比则下调明显(P0.05);而mi R-155、mi R-125b、mi R-146a分子在治疗前后无明显变化。结论:土龙祛疣洗剂治疗尖锐湿疣疗效肯定,可能通过下调mi R-21和上调mi R-203分子来发挥抗病毒的治疗作用。     

MicroRNA在丹酚酸B逆转肾小管上皮细胞转分化时的表达变化

目的:研究丹酚酸B逆转转化生长因子(TGF)-β1诱导的肾小管上皮细胞-间充质细胞转分化时microRNA(miRNA)表达谱的变化。方法:将体外培养的人近端肾小管上皮细胞系(HK-2)细胞分为3组:①对照组:未加入丹酚酸B或者TGF-β1;②TGF-β1组:在细胞培养基中加入TGF-β1(浓度为5ng/mL);③丹酚酸B逆转组:在细胞培养基中先TGF-β1(浓度为5ng/mL),48h后HK-2细胞成功诱导EMT后形成的间充质细胞,再更换为TGF-β1(浓度为5ng/mL)和丹酚酸B(50μmol/L)继续培养72h,采用倒置相差显微镜观察细胞形态学变化;免疫细胞化学染色检测细胞E-cadherin的表达情况;基因芯片检测各组细胞miRNA的表达变化。结果:①丹酚酸B具有逆转HK-2细胞EMT的作用;②与正常HK-2细胞比较,TGF-β1组有25种miRNA的表达出现显著改变,其中15种表达下调2倍以上,10种表达上调2倍以上。③与TGF-β1组比较,丹酚酸B逆转组,有44种miRNA的表达出现显著改变,其中24种表达下调2倍以上,20种表达上调2倍以上。④有10种miRNA表达在两组同时出现显著改变,其中8种在TGF-β1组明显下调,而在丹酚酸B逆转组明显上调,1种在TGF-β1组明显上调,而在丹酚酸B逆转组则明显下调。结论:丹酚酸B具有阻止慢性肾脏疾病进行性发展的潜能,而这一作用与其能有效调控miRNA的表达有关。