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Objective To compare the effects of three different methods for extracting short RNA-DNA hybrids, including the TRI reagent method , the phenol saturated with water method and the phenol saturated with Tris buffer method in order to facilitate studies on the biological function of RNA-DNA hybrids .Methods Short RNA fragments modifiedwith FAM at the 5′end and those modified with Cy 5 at the 5′end were synthesized .RNA and DNA fragments were annealed to form RNA-DNA hybrids.They were extracted with the above-mentioned 3 methods respectively .The extracted products were analyzed with electrophoresis .Results and Conclusion Short RNA-DNA hybrids can be extracted by the phenol saturated with water method and by the phenol saturated with Tris buffer method .The results can help study the function of short RNA-DNA hybrids .
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Objective To construct the recombinant plasmid of YTH domain family 2(YTHDF2)and express it in E.coli in order to obtain YTHDF2 fusion protein that was capable of binding m 6A-modified RNA.Methods The coding region of YTHDF2 gene was amplified by RT-PCR.The recombinant plasmid pET-28a-YTHDF2 was constructed and expressed in E.coli.The fusion protein was purified by Ni2+-NTA resin affinity chromatography, while the fusion protein activity was analyzed by Ni2+-NTA magnetic spheres.Results and Conclusion The recombinant YTHDF2 protein was expressed in E.coli BL21(DE3)and purified.YTHDF2 fusion protein was capable of binding RNA with m 6A-modification. The preparation of YTHDF2 fusion protein provides an essential tool to study the biological function of RNA with m6A-modification.
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Human telomeric repeat binding factor 1(TRF1) contains one Myb-type DNA-binding repeat and an amino-terminal acidic domain. It can bind to the duplex array of TTAGGG repeats at chromosome ends and is shown to be important in preserving genomic stability, maintaining cell proliferative capacity, and blocking the activation of DNA-damage cell cycle checkpoints. Interestingly, the double strand DNA breaks sensor ATM interacts with and phosphorylates Pin2/TRF1 and inhibits its function after DNA damage. Are there some proteins else that can interact with TRF1 and influence its function? In order to analysis the interaction between TRF1 and other proteins, we must prepare the antiserum that can recognize the endogenous TRF1 of cell lysates. TRF1 cDNA was amplified using cDNA Library of HeLa cell by PCR and cloned into pUCm-T vector. Sequence analysis reveals identity to the GenBank report. The TRF1 cDNA was subcloned into expression vector pET-28c(+) and expressed in E. coli as a fusion protein of 65 kD. The recombinant TRF1 can express in the supernatant (about 12.3% in total protein) on the induction of 0.5 mmol/L IPTG at 37 degrees C for 3 hours. Western-blot analysis showed the recombinant protein can react with TRF1 polyclonal antibody sc-6165 (from Santa Cruz Company). His6-TRF1 was purified by Ni(2+) -NTA resin affinity chromatography made by ourselves and showed to be homogeneity in SDS-PAGE. Rabbits were immunized for four times to prepare polyclonal antibody. The unpurified antiserum can recognize the overexpressed TRF1 with myc-tag and the endogenous Pin2/TRF1 of cell lysate by Western-blot at 1:1000 dilution. At 1:400 dilution, the antiserum can interact with endogenous TRF1 by Immunofluorescence cell staining analysis. The endogenous TRF1 in different cell lines, such as HepG2, 803, MCF7 and HeLa, locates in the nucleus. The soluble expression TRF1 and preparation of its antibody lay the foundation to study it further.