皮肤发育相关的miRNAs及其在糖尿病创面愈合中的作用*

微小核糖核酸（microRNA/miRNA）作为一类进化上保守的非编码小分子RNA,参与基因转录后的表达与 调控,其表达模式有一定的时间性和空间性,体现在不同的miRNAs在不同组织、不同发育阶段的表达水平差异。 某些miRNAs能够促进创面愈合,在创面愈合的炎症期抑制炎性介质的表达;某些miRNAs能够促进增生期创面 细胞的增殖、迁移,有利于创面的快速修复;在创面重塑期,某些miRNAs又能够通过抑制无痕愈合信号通路的 相关蛋白质来促使瘢痕修复。糖尿病创面通常伴随糖尿病周围神经病变、糖尿病血管病变和感染。部分miRNAs 通过调控特定基因的表达水平,激活或抑制不同且特定的信号通路,一定程度上促进了糖尿病创面的愈合。本文 主要综述了miRNA在创面愈合过程不同阶段的调控研究进展,以及miRNAs促进、抑制糖尿病创面愈合的机制, 以期为后续研究开拓新的思路。     

微小RNA调节骨骼肌发育与损伤修复的作用及其机制

microRNAs是一类非编码小RNAs分子,新近发现其具有重要的调节基因表达的功能,它能通过抑制翻译和降解靶mRNA来负性调控转录后水平的基因表达,miRNAs已经被证实在肌肉发育和肌细胞增殖和分化的调节中具有重要作用。最近研究发现,肌肉特异性转录因子控制一些microRNAs的表达,通过多种机制调节肌肉发育和功能。结合信息学、生物化学和遗传基因学方法,不仅将阐明骨骼肌microRNAs调控网络,更好地理解肌肉组织的调节,还将通过鉴定候选microRNAs的潜在临床应用靶点,增加肌肉营养不良的治疗干预的新机会。     

Titrated extract of Centella asiatica provides a UVB protective effect by altering microRNA expression profiles in human dermal fibroblasts

The titrated extract of Centella asiatica (TECA) is a reconstituted mixture comprising of asiatic acid, madecassic acid, asiaticoside and madecassoside, and is used as a therapeutic agent in wound healing and also as an anti-microbial, anticancer and anti-aging agent. Although these properties and the associated cell signaling pathways have been elucidated, the cellular mechanism of anti-photoaging upon ultraviolet (UV) exposure in normal human dermal fibroblasts (NHDFs) remains unknown. In this study, we investigated the photoprotective role of TECA via microRNA (miRNA) expression profiling analysis. Low dose of TECA did not exhibit toxicity and showed a protective effect against UVB irradiation in NDHFs. miRNA microarray experiments revealed that specific miRNAs were altered by TECA stimulation in UVB-irradiated NHDFs. Functional bioinformatic analysis showed that the putative target genes of the altered miRNAs were associated with the positive regulation of cell proliferation, anti-apoptosis, small GTPase- and Ras-mediated signal transduction and activation of MAPKK. Therefore, these results suggest that TECA may serve as a potential natural chemoprotective agent against UVB-mediated damage in NHDFs through changes in the expression of specific miRNAs.     

miRNAs and HIV: unforeseen determinants of host-pathogen interaction

Our understanding of the complexity of gene regulation has significantly improved in the last decade as the role of small non-coding RNAs, called microRNAs (miRNAs), has been appreciated. These 19–22 nucleotide RNA molecules are critical regulators of mRNA translation and turnover. The miRNAs bind via a protein complex to the 3′ untranslated region (3′ UTR) of mRNA, ultimately leading to mRNA translational inhibition, degradation, or repression. Although many mechanisms by which human immunodeficiency virus-1 (HIV-1) infection eventually induces catastrophic immune destruction have been elucidated, the important role that miRNAs play in HIV-1 pathogenesis is only now emerging. Accumulating evidence demonstrates that changes to endogenous miRNA levels following infection is important: in maintaining HIV-1 latency in resting CD4⁺ T cells, potentially affect immune function via changes to cytokines such as interleukin-2 (IL-2) and IL-10 and may predict disease progression. We review the roles that both viral and host miRNAs play in different cell types and disease conditions that are important in HIV-1 infection and discuss how miRNAs affect key immunomodulatory molecules contributing to immune dysfunction. Further, we discuss whether miRNAs may be used as novel biomarkers in serum and the potential to modulate miRNA levels as a unique approach to combating this pathogen.     

miRNAs at the heart of the matter

Cardiovascular disease is among the main causes of morbidity and mortality in developed countries. The pathological process of the heart is associated with altered expression profile of genes that are important for cardiac function. MicroRNAs (miRNAs) have emerged as one of the central players of gene expression regulation. The implications of miRNAs in the pathological process of cardiovascular system have recently been recognized, representing the most rapidly evolving research field. Here, we summarize and analyze the currently available data from our own laboratory and other groups, providing a comprehensive overview of miRNA function in the heart, including a brief introduction of miRNA biology, expression profile of miRNAs in cardiac tissue, role of miRNAs in cardiac hypertrophy and heart failure, the arrhythmogenic potential of miRNAs, the involvement of miRNAs in vascular angiogenesis, and regulation of cardiomyocyte apoptosis by miRNAs. The target genes and signaling pathways linking the miRNAs to cardiovascular disease are highlighted. The applications of miRNA interference technologies for manipulating miRNA expression, stability, and function as new strategies for molecular therapy of human disease are evaluated. Finally, some specific issues related to future directions of the research on miRNAs relevant to cardiovascular disease are pinpointed and speculated.     

Genome-wide identification of SNPs in microRNA genes and the SNP effects on microRNA target binding and biogenesis

MicroRNAs (miRNAs) are studied as key regulators of gene expression involved in different diseases. Several single nucleotide polymorphisms (SNPs) in miRNA genes or target sites (miRNA-related SNPs) have been proved to be associated with human diseases by affecting the miRNA-mediated regulatory function. To systematically analyze miRNA-related SNPs and their effects, we performed a genome-wide scan for SNPs in human pre-miRNAs, miRNA flanking regions, target sites, and designed a pipeline to predict the effects of them on miRNA-target interaction. As a result, we identified 48 SNPs in human miRNA seed regions and thousands of SNPs in 3' untranslated regions with the potential to either disturb or create miRNA-target interactions. Furthermore, we experimentally confirmed seven loss-of-function SNPs and one gain-of-function SNP by luciferase assay. This is the first case of experimental validation of an SNP in an miRNA creating a novel miRNA target binding. All useful data were complied into miRNASNP, a user-friendly free online database (http://www.bioguo.org/miRNASNP/). These data will be a useful resource for studying miRNA function, identifying disease-associated miRNAs, and further personalized medicine.     

MicroRNAs in tumorigenesis: a primer

MicroRNAs (miRNAs) are a family of 21- to 25-nucleotide, noncoding small RNAs that primarily function as gene regulators. It is surprising that these tiny molecules, so diverse and consequential in their biological functions, have been hidden for so many years. Thanks to their discovery, cancer research has found a new arena. Aided by innovative molecular techniques, the research of miRNAs in oncology has progressed rapidly in recent years. miRNA abnormalities are becoming an emerging theme in cancer research. Specific functions of miRNAs, many of which are relevant to cancer development, are becoming apparent. The value of miRNAs in cancer classification and prognostication is being explored, and new therapeutic strategies targeting miRNAs are being developed. Because there is great promise that miRNA research will provide breakthroughs in the understanding of cancer pathogenesis and development of new valuable prognostic markers, pathologists should be adequately informed of this rapidly progressing field. Here, we offer a review on the basics of miRNA biology and the emerging role of miRNA in cancer pathogenesis, classification, and prognostication, including highlights of the involvement of specific miRNAs in different tumor types.     

MicroRNA Microarray Expression Profiling in Human Myocardial Infarction

MicroRNAs (miRNAs), small non-coding RNA molecules, are negative regulators of gene expression. Recent studies have indicated their role in various forms of cardiovascular disease. In spite of the number of miRNA microarray analyses performed, little is known about the genome-wide miRNA expression pattern in human myocardial infarction (MI). Using miRNA microarrays and bioinformatic analysis, miRNA expression was analyzed on human MI and foetal hearts compared to healthy adult hearts, to determine whether there is any similar expression pattern between MI and foetal hearts, and to identified miRNAs that have not previously been described as dysregulated in cardiovascular diseases. Of 719 miRNAs analyzed, ∼ 50% were expressed in human hearts, 77 miRNAs were absent from all tested tissues and 57 were confidently dysregulated in at least one tested group. Some expression patterns appeared to be similar in MI and foetal hearts. Bioinformatic analysis revealed 10 miRNAs as dysregulated in MI not yet related to cardiovascular disease, and 5 miRNAs previously described only in animal models of cardiovascular diseases. Finally, qRT-PCR analysis confirmed dysregulation of 7 miRNAs, miR-150, miR-186, miR-210, miR-451, and muscle-specific, miR-1 and miR-133a/b; all of these are believed to be involved in various physiological and pathological processes.     

Identification of a reference gene for the quantification of mRNA and miRNA expression during skin wound healing

Aim: Wound healing is a coordinated process to restore tissue homeostasis and reestablish the protective barrier of the skin. miRNAs may modulate the expression of target genes to contribute to repair processes, but due to the complexity of the tissue it is challenging to quantify gene expression during the distinct phases of wound repair. Here, we aimed to identify a common reference gene to quantify changes in miRNA and mRNA expression during skin wound healing. Methods: Quantitative real-time PCR and bioinformatic analysis tools were used to identify suitable reference genes during skin repair and their reliability was tested by studying the expression of mRNAs and miRNAs. Results: Morphological assessment of wounds showed that the injury model recapitulates the distinct phases of skin repair. Non-degraded RNA could be isolated from skin and wounds and used to study the expression of non-coding small nuclear RNAs during wound healing. Among those, RNU6B was most constantly expressed during skin repair. Using this reference gene we could confirm the transient upregulation of IL-1β and PTPRC/CD45 during the early phase as well as the increased expression of collagen type I at later stages of repair and validate the differential expression of miR-204, miR-205, and miR-31 in skin wounds. In contrast to Gapdh the normalization to multiple reference genes gave a similar outcome. Conclusion: RNU6B is an accurate alternative normalizer to quantify mRNA and miRNA expression during the distinct phases of skin wound healing when analysis of multiple reference genes is not feasible.     

MicroRNA-141 confers resistance to cisplatin-induced apoptosis by targeting YAP1 in human esophageal squamous cell carcinoma

MicroRNAs (miRNAs) are endogenous non-coding RNAs that function as negative regulators of gene expression. Alterations in miRNA expression have been shown to affect tumor growth and response to chemotherapy. In this study, we explored the possible role of miRNAs in cisplatin resistance in esophageal squamous cell carcinoma (ESCC). First we assessed the sensitivity of nine human ESCC cell lines (KYSE series) to cisplatin using an in vitro cell viability assay, and then we compared the miRNA profiles of the cisplatin-sensitive and -resistant cell lines by miRNA microarray analysis. The two groups showed markedly different miRNA expression profiles, and 10 miRNAs were found to be regulated differentially between the two groups. When miR-141, which was the most highly expressed miRNA in the cisplatin-resistant cell lines, was expressed ectopically in the cisplatin-sensitive cell lines, cell viability after cisplatin treatment was increased significantly. Furthermore, we found that miR-141 directly targeted the 3'-untranslated region of YAP1, which is known to have a crucial role in apoptosis induced by DNA-damaging agents, and thus downregulated YAP1 expression. Our study highlights an important regulatory role for miR-141 in the development of cisplatin resistance in ESCC.