Prediction and verification of miRNA expression in human and rat retinas

PURPOSE: MicroRNAs (miRNAs) play a global role in regulating gene expression and have important tissue-specific functions. Little is known about their role in the retina. The purpose of this study was to establish the retinal expression of those miRNAs predicted to target genes involved in vision. METHODS: miRNAs potentially targeting important "retinal" genes, as defined by expression pattern and implication in disease, were predicted using a published algorithm (TargetScan; Envisioneering Medical Technologies, St. Louis, MO). The presence of candidate miRNAs in human and rat retinal RNA was assessed by RT-PCR. cDNA levels for each miRNA were determined by quantitative PCR. The ability to discriminate between miRNAs varying by a single nucleotide was assessed. The activity of miR-124 and miR-29 against predicted target sites in Rdh10 and Impdh1 was tested by cotransfection of miRNA mimics and luciferase reporter plasmids. RESULTS: Sixty-seven miRNAs were predicted to target one or more of the 320 retinal genes listed herein. All 11 candidate miRNAs tested were expressed in the retina, including miR-7, miR-124, miR135a, and miR135b. Relative levels of individual miRNAs were similar between rats and humans. The Rdh10 3'UTR, which contains a predicted miR-124 target site, mediated the inhibition of luciferase activity by miR-124 mimics in cell culture. CONCLUSIONS: Many miRNAs likely to regulate genes important for retinal function are present in the retina. Conservation of miRNA retinal expression patterns from rats to humans supports evidence from other tissues that disruption of miRNAs is a likely cause of a range of visual abnormalities.     

微小RNA与视网膜发育相关性研究进展

微小RNA(miRNA)是相对分子质量较小、性质稳定的RNA,通过与目的mRNA的部分互补序列碱基互补配对而在转录后水平调节动物、植物的基因表达及抑制蛋白质合成.目前发现在视网膜中表达的miRNA有200多种,miRNA对基因的表达调控影响了视网膜的正常发育,与神经视网膜的发生、视网膜光感受器的分型及正常数量维持、神经节细胞的存活及轴突生长、视网膜色素上皮层的发育均有密切联系.此外,miRNA的调控还与视网膜损伤后的再生有关.miRNA对视网膜发育的调控主要通过直接靶向调节与此有关的某些目的基因的表达,或通过调节某些信号通路组分来实现,在视网膜发育过程中,miRNA功能的正常发挥为视网膜正常形态结构的形成提供了保障,从而为其发挥正常的生理功能提供了物质基础.现就脊椎动物视网膜中miRNA的生物学功能与视网膜发育的相关性研究进展进行综述.     

微小RNAs在眼组织的表达及其与眼科疾病的关系

微小核糖核酸（miRNAs）是内源性小分子非编码调控RNAs,通过抑制转录或降解mRNA调控基因的表达。研究发现miRNAs涉及组织分化和生长等许多重要的生物进程,显示出组织特异性和生长阶段特异性,也参与新生血管形成及很多病理进程,如肿瘤血管新生、氧化应激、免疫反应和炎症。目前,视网膜、晶状体和角膜的miRNAs转录组已经建立,并可能在未来作为眼科疾病治疗的手段之一。就miRNAs在眼组织中的分布及其在眼病中的异常表达进行综述。     

miR-204调控眼科疾病的研究进展

微小RNA(miRNA)是一类广泛存在于真核生物体内、长度为20～ 25个核苷酸、具有调控功能的非编码单链RNA,参与机体的各种生命进程,包括细胞的生长、分化、增生、凋亡和自噬.miRNA-204-5p(miR-204-5p)是由位于染色体9q21.12上的TRPM3大内含子6表达.研究发现,miR-204在角膜损伤愈合过程中起着十分重要的作用,亦能够保持静止状态下血-视网膜屏障的稳定,并且在人小梁网细胞中,miR-204与细胞的凋亡、生存能力以及炎症介质的表达有着重要联系.这些研究都表明miR-204在眼部呈多维表达,提示miR-204很可能是不同眼部疾病的关键miRNA.本文从miRNA的生物合成,miR-204与糖尿病性角膜病变、视网膜色素上皮细胞、人小梁网细胞、年龄相关性白内障、糖尿病视网膜病变、视网膜母细胞瘤的关系,以及miR-204与自噬的相关研究等几个方面,就miR-204调控眼科疾病的研究进展进行综述,为探寻眼部难治性疾病的防治方法寻找新的靶点.     

MicroRNAs在晶状体中的功能

MicroRNAs(miRNAs)是一类包含21～23个碱基的非编码单链小分子RNA。通过与靶基因3'端非翻译区(UTR)不完全碱基配对,使mRNA降解或抑制靶mRNA的翻译,进而发挥基因调控作用。miRNAs广泛参与生物体内的多种生理和病理过程,通过其表达量的上调或下调,影响细胞发育和疾病的进程。近年来许多研究表明,miRNAs在眼部的多种组织,包括晶状体、视网膜和角膜中均有表达,其异常表达可能与某些眼部疾病的发生、发展有密切关系。本文综述近年来miRNAs在晶状体中的表达、功能及研究进展,以期寻求可用于临床诊断、治疗晶状体混浊的新型靶点。     

MicroRNAs在眼部的表达及作用研究进展

MicroRNAs(miRNAs)是一类内源、非编码、具有调节作用的小分子RNAs,通过下调靶向mRNAs和(或)抑制其翻译,从而在转录后水平调节基因的表达。miRNAs涉及许多重要的生物学过程,如发育时间、分化增殖、形态发生以及凋亡等,因此其在这些过程中所发挥的作用备受关注。许多眼部的miRNAs表现出独特的组织和发育阶段特异性的表达模式,提示它们在眼中可能具有重要的功能。探索miRNAs在眼球发育及病理过程中的作用已成为眼部研究的新热点,有望为眼部疾病的诊断和治疗提供新的研究方向。现就近年来关于miRNAs的研究进行综述。     

MicroRNA及其在眼科领域的研究进展

MicroRNAs是一组可负性调控基因表达的非编码蛋白质的短序列RNA,参与调节细胞的生长发育、分化、增殖、凋亡等重要的生理过程.它们主要通过降解mRNA或抑制靶基因的翻译发挥调节作用.目前已发现有400多种MicroRNAs在人类基因组中表达.越来越多的研究表明很多特定的MicroRNAs在眼部很多组织中包括角膜、晶状体、视网膜中均有表达.本文就MicroRNAs的来源、结构、功能、在眼部的表达及未来作为治疗眼部疾病一种可能手段的前景进行综述.(中华眼科杂志,2009,45:280-284)     

Circadian rhythms in the eye: the physiological significance of melatonin receptors in ocular tissues

Many biological processes display circadian rhythms in activity, which presumably operate to coordinate cellular functions with daily environmental oscillations. The diurnal changes in environmental illumination are conveyed by the retina to the brain to entrain circadian rhythms throughout the body. Many ocular tissues themselves exhibit circadian rhythms of activity to optimize specific processes which require coordination with the light-dark cycle. The circadian signaling molecule, melatonin, is secreted into the circulation from the pineal gland, and is also produced within specific ocular cells such as retinal photoreceptors, ciliary epithelial cells, and perhaps cells of the lens. Melatonin appears to entrain many aspects of the biological clock via activation of specific G-protein-coupled integral membrane melatonin receptors. Melatonin receptors have been identified in many ocular tissues, including the neural retina, retinal pigment epithelium, ciliary body, cornea, sclera, and lens. This review will describe the circadian rhythmicity of some of the functions of these various ocular tissues, and will attempt to correlate these circadian activities with the expression of specific G-protein-coupled melatonin receptors, the role of melatonin in the regulation of circadian activity in ocular tissues, and its potential role in ocular diseases.     

TRPM3/miR-204复合位点调控眼部疾病的研究进展

微小RNA(micro RNA,miRNA)是最主要的基因表达调控因子之一,涉及多种细胞、组织和器官的生长、发育、分化及凋亡等过程。TRPM3基因位于人类9号染色体的长臂,是钙通透性离子通道TRP家族M亚家族中成员之一。miR-204位于TRPM3内含子6上,通过对靶mRNAs的切割或抑制其翻译参与转录后基因表达的调控。研究显示TRPM3/miR-204复合位点在白内障、青光眼、角膜新生血管、角膜损伤愈合、视网膜疾病、视神经疾病等眼部疾病的发生发展中起着重要的调控作用。本文从TRPM3/miR-204分子通路的生物学功能、在眼部的表达与调控以及其与多种眼部疾病的相关性研究进展进行综述。     

Lysosomal enzymes in ocular tissues and diseases

Lysosomal enzymes are distributed widely in various ocular tissues. Among these tissues, the uvea and retina show the higher enzyme activities of acid phosphates, beta-blucuronidase, alpha-fucosidase, alpha-mannosidase, arylsulfatase, cathepsin D, cathepsin B and others. The particular role of lysosomal enzymes in the pathogenic processes of ocular diseases such as storage disease, uveitis, retinal degeneration, retinal detachment, corneal dystrophy and glaucoma is strongly suggested. The enzymes also have additional importance in ocular physiopathology.     

Identification of androgen, estrogen and progesterone receptor mRNAs in the eye

PURPOSE: Previous research has demonstrated that sex steroids exert a significant influence on the structure and function of numerous ocular tissues. To begin to explore the underlying basis of this hormone action, we examined whether various anterior and posterior tissues of the eye contain androgen, estrogen and progesterone receptor mRNAs. METHODS: Tissue samples were obtained from adult male and female rats, rabbits and humans, processed for the isolation of total RNA and analyzed by RT-PCR, agarose gel electrophoresis and Southern blot hybridization. All PCR amplifications included positive and negative controls. RESULTS: Our findings showed that androgen, estrogen and/or progesterone receptor mRNAs are present in the lacrimal gland, lacrimal gland acinar epithelial cells, meibomian gland, lid, palpebral and bulbar conjunctivae, cornea, iris/ciliary body, lens, retina/uvea, retina/choroid and retinal pigment epithelial cells of rats, rabbits or humans. CONCLUSIONS: Our findings demonstrate that sex steroid receptor mRNAs exist in a variety of ocular tissues and suggest that these sites may represent target organs for androgens, estrogens and/or progestins.     

New focus on alpha-crystallins in retinal neurodegenerative diseases

The crystallin proteins were initially identified as structural proteins of the ocular lens and have been recently demonstrated to be expressed in normal retina. They are dramatically upregulated by a large range of retinal diseases including diabetic retinopathy, age-related macular degeneration, uveitis, trauma and ischemia. The crystallin family of proteins is composed of alpha-, beta- and gamma-crystallin. Alpha-crystallins, which are small heat shock proteins, have received substantial attention recently. This review summarizes the current knowledge of alpha-crystallins in retinal diseases, their roles in retinal neuron cell survival and retinal inflammation, and the regulation of their expression and activity. Their potential role in the development of new treatments for neurodegenerative diseases is also discussed.     

Colocalization of neuropilin-1 and Flk-1 in retinal neovascularization in a mouse model of retinopathy

PURPOSE. To investigate the mechanisms of the development of retinal neovascularization, the localizations of vascular endothelial (VEGF) receptors Flk-1 and neuropilin (NP)-1 mRNAs were examined. METHODS. The model of retinopathy of prematurity (ROP) was produced by ischemia-induced ocular neovascularization, by exposing postnatal day-7 mice to 75% oxygen for 5 days and then returning them to room air for 5 days. Retinal neovascularization was visualized by injection of fluorescein-dextran. Expression of Flk-1 and NP-1 mRNAs were examined by in situ hybridization with flatmount and serial sections of the retina. The localization of NP-1 was also confirmed by immunohistochemistry. Blood vessel patterns were characterized by immunohistochemical localization of von Willebrand factor (vWF). RESULTS. Flatmount in situ hybridization showed intense expression of NP-1 and Flk-1 mRNAs colocalized in the area of neovascularization. In situ hybridization of serial sections of the retina revealed that expression of Flk-1 and NP-1 was restricted to neovascularized vessels of the retina from ROP mice. CONCLUSIONS. The restricted expression of Flk-1 and NP-1 on neovascularized vessels suggests that these molecules may play important roles in retinal neovascularization. This is the first report of the colocalization of NP-1 and Flk-1 on neovascularized vessels of the retina from ROP mice.     

BMP4/Smad信号通路的分子机制及其在眼部疾病中的作用

骨形成蛋白4（BMP4）通过Smad信号通路向下游传递信号,同时与Wnt/β-catenin、FGF等信号通路相互作用,调节一系列的病理生理活动。BMP4/Smad信号通路对眼具有重要作用。BMP4/Smad信号通路与眼前节、晶状体、视网膜的发育密切相关。同时,BMP4在成熟眼组织中高度表达,意味着BMP4/Smad信号通路与某些眼部疾病的发病机制有关。BMP4/Smad信号通路在维持角膜上皮稳态、视网膜神经的保护及修复方面起一定作用,同时还与青光眼、年龄相关性黄斑变性、增生型玻璃体视网膜病变等疾病的发生密切相关。本文主要讲述了BMP4/Smad信号通路的分子机制,并详细介绍了BMP4/Smad信号通路在眼发育和一些眼部疾病中的作用。     

过氧化物酶体增生物激活受体γ在鼠眼球中的分布

背景过氧化物酶体增生物激活受体γ（PPAR-γ）是一类由配体激活的核转录因子,是潜在的抗炎、抗纤维增生、抗新生血管形成及神经保护因子,其在动物和人体组织中的生理病理功能是目前的研究热点之一,PPARγ与眼科疾病的研究受到关注。目的研究PPARγ在眼部不同组织细胞中的表达,为PPARγ激动剂在眼科疾病治疗中的应用提供参考依据。方法取SPF级C57BL／6J小鼠6只及SD大鼠1只,用质量分数3％水合氯醛麻醉处死后立即摘除眼球,采用Western blot法检测小鼠角膜、晶状体和视网膜组织中PPARγ蛋白的表达;采用免疫组织化学和免疫荧光化学法检测PPARγ在小鼠角膜、晶状体、视网膜、睫状体及视神经组织中的表达及定位。结果Western blot法检测表明,PPARγ在小鼠角膜、晶状体、视网膜中均呈阳性表达。免疫组织化学和免疫荧光化学法检测显示,PPARγ在角膜组织中主要表达于上皮层,以基底细胞染色最强,而角膜内皮及基质细胞上仅有弱表达。PPARγ在晶状体中主要表达于上皮细胞和浅皮质层;在视网膜组织中,PPARγ主要表达于视网膜节细胞层、内丛状层、外丛状层和内核层,此外PPARγ在SD大鼠睫状体组织中主要表达于无色素上皮。免疫荧光化学法检测显示,其在视网膜中与Muller细胞标志物谷氨酰胺合成酶（GS）共定位表达明显;PPARγ在视神经组织中的表达与星形胶质细胞标志物胶质纤维酸性蛋白（GFAP）共定位表达明显。结论PPARγ广泛分布于眼不同组织中并呈特异性表达,该结果为相关眼科疾病的靶向治疗提供了依据。     

高眼压缺血-再灌注中视网膜NOS的表达及L-NAME对其表达的影响

目的探讨高眼压缺血－再灌注损伤时视网膜一氧化氮合酶（ＮＯＳ）的表达、Ｌ－ＮＡＭＥ对ＮＯＳ表达的影响及视网膜ＮＯＳ的作用。方法用免疫组织化学ＳＡＢＣ法检测ｎＮＯＳ，ｅＮＯＳ和ｉＮＯＳ在高眼压缺血－再灌注模型视网膜中的表达及ＮＯＳ抑制剂Ｌ－ＮＡＭＥ对其表达的影响。结果在高眼压缺血－再灌注下，视网膜神经节细胞、神经胶质细胞ｎＮＯＳ，ｅＮＯＳ，ｉＮＯＳ均呈阳性，对照组ｎＮＯＳ呈弱阳性；注射Ｌ－ＮＡＭＥ后，在高眼压缺血－再灌注中，视网膜神经节细胞、神经胶质细胞均呈ｉＮＯＳ强阳性，ｎＮＯＳ，ｅＮＯＳ呈阴性。结论在高眼压缺血－再灌注中ｎＮＯＳ，ｅＮＯＳ，ｉＮＯＳ合成的一氧化氮（ＮＯ）可能对视网膜细胞等有细胞毒性作用；Ｌ－ＮＡＭＥ通过抑制ｎＮＯＳ，ｅＮＯＳ的活性，对高眼压缺血－再灌注视网膜损伤产生保护作用。