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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Montmorillonite catalysis of RNA oligomer formation in aqueous solution. A model for the prebiotic formation of RNA

Oligomers of adenylic acid of up to the 11-mer in length are formed by the reaction of the phosphorimidazolide of adenosine (ImpA) in pH 8 aqueous solution at room temperature in the presence of Na(+)-montmorillonite. These oligomers are joined by phosphodiester bonds in which the 3',5'-linkage predominates over the 2',5'-linkage by a 2:1 ratio. Reaction of a 9:1 mixture of ImpA, A5'ppA results in the formation of oligomers with a 3:1 ratio of 3',5'- to 2',5'-linked phosphodiester bonds. A high proportion of these oligomers contain the A5'ppA grouping. A5'ppA reacts much more rapidly with ImpA than does 5'-ADP (ppA) or 5'-ATP (pppA). The exchangeable cation associated with the montmorillonite effects the observed catalysis with Li+, Na+, NH4+, and Ca2+ being the more effective while Mg2+ and Al3+ are almost ineffective catalysts. 2',5'-Linked oligomers, up to the tetramer in length, are formed using UO2(2+)-montmorillonite. The structure analysis of individual oligomer fractions was performed by selective enzymatic and KOH hydrolytic studies followed by HPLC analysis of the reaction products. It is concluded from the composition of the oligomers that the rate of addition ImpA to a 3'-terminus containing a 2',5'-linkage is slower than the addition to a nucleoside joined by a 3',5'-linked phosphodiester bond. The potential importance of mineral catalysis of the formation of RNA and other oligomers on primitive Earth is discussed.

Non-NASA Center↗
DOE OSTI2018

The long non-coding RNA PCSEAT exhibits an oncogenic property in prostate cancer and functions as a competing endogenous RNA that associates with EZH2

Highlights: • PCSEAT is specifically overexpressed in prostate cancer. • PCSEAT promotes the growth and motility of prostate cancer cells. • PCSEAT regulates EZH2 by competitively ‘sponge’ miRNA-143-3p and miRNA-24-2-5p. • PCSEAT may serve as a biomarker for EZH2 inhibitors. • PCSEAT can be transmitted via exosomes and function in recipient cell. Prostate cancer (PCa) is the most common malignancy and the leading cause of cancer deaths in males. Recent studies demonstrate that long non-coding RNAs (lncRNAs) are involved in many aspects of PCa. However, their biological roles in PCa remain imperfectly understood. Here, we characterized an lncRNA, PCa specific expression and EZH2-associated transcript (PCSEAT, annotated as PRCAT38), which is specifically overexpressed in PCa. We further demonstrated that knockdown of PCSEAT results in the reduction of PCa cell growth and motility, and overexpression of PCSEAT reverses these phenotypes. Furthermore, bioactive PCSEAT is incorporated into exosomes and transmitted to adjacent cells, thus promoting cell proliferation and motility. Mechanistically, we found that PCSEAT promotes cell proliferation, at least in part by affecting miR-143-3p- and miR-24-2-5p-mediated regulation of EZH2, suggesting that PCSEAT and EZH2 competitively ‘sponge’ miR-143-3p and miR-24-2-5p. Overall, our results reveal that PCSEAT is specifically overexpressed in PCa patients and a potential oncogene in PCa cells via mediating EZH2 activity, indicating that PCSEAT may be a potential therapeutic target in PCa.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

The CRISPR RNA-guided surveillance complex in Escherichia coli accommodates extended RNA spacers

Bacteria and archaea acquire resistance to foreign genetic elements by integrating fragments of foreign DNA into CRISPR (clustered regularly interspaced short palindromic repeats) loci. In Escherichia coli , CRISPR-derived RNAs (crRNAs) assemble with Cas proteins into a multi-subunit surveillance complex called Cascade (CRISPR-associated complex for antiviral defense). Cascade recognizes DNA targets via protein-mediated recognition of a protospacer adjacent motif and complementary base pairing between the crRNA spacer and the DNA target. Previously determined structures of Cascade showed that the crRNA is stretched along an oligomeric protein assembly, leading us to ask how crRNA length impacts the assembly and function of this complex. We found that extending the spacer portion of the crRNA resulted in larger Cascade complexes with altered stoichiometry and preserved in vitro binding affinity for target DNA. Longer spacers also preserved the in vivo ability of Cascade to repress target gene expression and to recruit the Cas3 endonuclease for target degradation. Lastly, longer spacers exhibited enhanced silencing at particular target locations and were sensitive to mismatches within the extended region. These findings demonstrate the flexibility of the Type I-E CRISPR machinery and suggest that spacer length can be modified to fine-tune Cascade activity.

60 APPLIED LIFE SCIENCES↗