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Elizabeth O'Day Minh T. N. Le Shunsuke Imai Shen Mynn Tan Rory Kirchner Haribabu Arthanari Oliver Hofmann Gerhard Wagner Judy Lieberman 《The Journal of biological chemistry》2015,290(29):17909-17922
Lin28 is an evolutionarily conserved RNA-binding protein that inhibits processing of pre-let-7 microRNAs (miRNAs) and regulates translation of mRNAs that control developmental timing, pluripotency, metabolism, and tumorigenesis. The RNA features that mediate Lin28 binding to the terminal loops of let-7 pre-miRNAs and to Lin28-responsive elements (LREs) in mRNAs are not well defined. Here we show that Lin28 target datasets are enriched for RNA sequences predicted to contain stable planar structures of 4 guanines known as G-quartets (G4s). The imino NMR spectra of pre-let-7 loops and LREs contain resonances characteristic of G4 hydrogen bonds. These sequences bind to a G4-binding fluorescent dye, N-methyl-mesoporphyrin IX (NMM). Mutations and truncations in the RNA sequence that prevent G4 formation also prevent Lin28 binding. The addition of Lin28 to a pre-let-7 loop or an LRE reduces G4 resonance intensity and NMM binding, suggesting that Lin28 may function to remodel G4s. Further, we show that NMM inhibits Lin28 binding. Incubation of a human embryonal carcinoma cell line with NMM reduces its stem cell traits. In particular it increases mature let-7 levels, decreases OCT4, HMGA1, CCNB1, CDK4, and Lin28A protein, decreases sphere formation, and inhibits colony formation. Our results suggest a previously unknown structural feature of Lin28 targets and a new strategy for manipulating Lin28 function. 相似文献
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Identification of primary and secondary metabolites with phosphorus status‐dependent abundance in Arabidopsis,and of the transcription factor PHR1 as a major regulator of metabolic changes during phosphorus limitation 下载免费PDF全文
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Differential expression of miRNAs and their target genes in senescing leaves and siliques: insights from deep sequencing of small RNAs and cleaved target RNAs 下载免费PDF全文
SHAWN R. THATCHER SHAUL BURD CHRISTOPHER WRIGHT AMNON LERS PAMELA J. GREEN 《Plant, cell & environment》2015,38(1):188-200
MicroRNAs (miRNAs) are a class of small RNAs, which typically function by guiding cleavage of target mRNAs. They are known to play roles in a variety of plant processes including development, responses to environmental stresses and senescence. To identify senescence regulation of miRNAs in Arabidopsis thaliana, eight small RNA libraries were constructed and sequenced at four different stages of development and senescence from both leaves and siliques, resulting in more than 200 million genome‐matched sequences. Parallel analysis of RNA ends libraries, which enable the large‐scale examination of miRNA‐guided cleavage products, were constructed and sequenced, resulting in over 750 million genome‐matched sequences. These large datasets led to the identification a new senescence‐inducible small RNA locus, as well as new regulation of known miRNAs and their target genes during senescence, many of which have established roles in nutrient responsiveness and cell structural integrity. In keeping with remobilization of nutrients thought to occur during senescence, many miRNAs and targets had opposite expression pattern changes between leaf and silique tissues during the progression of senescence. Taken together, these findings highlight the integral role that miRNAs may play in the remobilization of resources and alteration of cellular structure that is known to occur in senescence. 相似文献
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Development of plants resistant to tomato geminiviruses using artificial trans‐acting small interfering RNA 下载免费PDF全文
Archana Singh Jyoti Taneja Indranil Dasgupta Sunil Kumar Mukherjee 《Molecular Plant Pathology》2015,16(7):724-734
RNA interference (RNAi), a conserved RNA‐mediated gene regulatory mechanism in eukaryotes, plays an important role in plant growth and development, and as an antiviral defence system in plants. As a counter‐strategy, plant viruses encode RNAi suppressors to suppress the RNAi pathways and consequently down‐regulate plant defence. In geminiviruses, the proteins AC2, AC4 and AV2 are known to act as RNAi suppressors. In this study, we have designed a gene silencing vector using the features of trans‐acting small interfering RNA (tasiRNA), which is simple and can be used to target multiple genes at a time employing a single‐step cloning procedure. This vector was used to target two RNAi suppressor proteins (AC2 and AC4) of the geminivirus, Tomato leaf curl New Delhi virus (ToLCNDV). The vector containing fragments of ToLCNDV AC2 and AC4 genes, on agro‐infiltration, produced copious quantities of AC2 and AC4 specific siRNA in both tobacco and tomato plants. On challenge inoculation of the agro‐infiltrated plants with ToLCNDV, most plants showed an absence of symptoms and low accumulation of viral DNA. Transgenic tobacco plants were raised using the AC2 and AC4 tasiRNA‐generating constructs, and T1 plants, obtained from the primary transgenic plants, were tested for resistance separately against ToLCNDV and Tomato leaf curl Gujarat virus. Most plants showed an absence of symptoms and low accumulation of the corresponding viruses, the resistance being generally proportional to the amounts of siRNA produced against AC2 and AC4 genes. This is the first report of the use of artificial tasiRNA to generate resistance against an important plant virus. 相似文献
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