02321nas a2200181   4500008004100000022001400041245010600055210006900161260007100230300001400301490000700315520160500322100002101927700002501948700001701973700001801990856013102008       2013                        eng d  a0006-296000aG-quadruplex augments translation in the 5 ` untranslated region of transforming growth factor beta 20 aGquadruplex augments translation in the 5 untranslated region of  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAR  a1528-15380 v523 a<p>Transforming growth factor beta 2 (TGF beta 2) is a versatile cytokine with a prominent role in cell migration, invasion, cellular development, and immunomodulation. TGF beta 2 promotes the malignancy of tumors by inducing epithelial-mesenchymal transition, angiogenesis, and immunosuppression. As it is well-documented that nucleic acid secondary structure can regulate gene expression, we assessed whether any secondary motif regulates its expression at the post-transcriptional level. Bioinformatics analysis predicts an existence of a 23-nucleotide putative G-quadruplex sequence (PG4) in the 5' untranslated region (UTR) of TGF beta 2 mRNA. The ability of this stretch of sequence to form a highly stable, intramolecular parallel quadruplex was demonstrated using ultraviolet and circular dichroism spectroscopy. Footprinting studies further validated its existence in the presence of a neighboring nucleotide sequence. Following structural characterization, we evaluated the biological relevance of this secondary motif using a dual luciferase assay. Although PG4 inhibits the expression of the reporter gene, its presence in the context of the entire 5' UTR sequence interestingly enhances gene expression. Mutation or removal of the G-quadruplex sequence from the 5' UTR of the gene diminished the level of expression of this gene at the translational level. Thus, here we highlight an activating role of the G-quadruplex in modulating gene expression of TGF beta 2 at the translational level and its potential to be used as a target for the development of therapeutics against cancer.</p>1 aAgarwala, Prachi1 aPandey, Satyaprakash1 aMapa, Koyeli1 aMaiti, Souvik  uhttps://library.ncl.res.in/content/g-quadruplex-augments-translation-5-untranslated-region-transforming-growth-factor-beta-2-002312nas a2200169   4500008004100000022001400041245018500055210006900240260007100309300001400380490000700394520156300401100001901964700001701983700001802000856012402018       2014                        eng d  a0006-296000aUnderstanding the effect of locked nucleic acid and 2 `-O-methyl modification on the hybridization thermodynamics of a miRNA-mRNA pair in the presence and absence of AfPiwi protein0 aUnderstanding the effect of locked nucleic acid and 2 Omethyl mo  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAR  a1607-16150 v533 a<p>miRNAs are some of the key epigenetic regulators of gene expression. They act through hybridization with their target mRNA and modulate the level of respective proteins via different mechanisms. Various cancer conditions are known to be associated with up- and downregulation of the oncogenic and tumor suppressor miRNAs, respectively. The levels of aberrantly expressed oncogenic miRNAs can be downregulated in different ways. Similarly, restoration of tumor suppressor miRNAs to their normal levels can be achieved using miRNA mimics. However, the use of miRNA mimics is limited by their reduced biostability and function. We have studied the hybridization thermodynamics of the miRNA 26a (11-mer, including the seed sequence) guide strand with the mRNA (11-mer) target strand in the absence and presence of AfPiwi protein. We have also inserted locked nucleic acids (LNAs) and 2'-O-methyl-modified nucleotides into the guide strand, in a walk-through manner, to assess their effect on the binding efficiency between guide and target RNA. Insertion of LNA and 2'-O-methyl-modified nucleotides into the guide strand helped to strengthen the binding affinity irrespective of the position of insertion. However, in the presence of AfPiwi protein, these modifications reduced the binding affinity to different extents depending on the position of insertion. Insertion of a modification leads to an increase in the enthalpic contribution with an increased unfavorable entropic contribution, which negatively compensates for the higher favorable enthalpy.</p>1 aKumar, Santosh1 aMapa, Koyeli1 aMaiti, Souvik  uhttps://library.ncl.res.in/content/understanding-effect-locked-nucleic-acid-and-2-o-methyl-modification-hybridization-0