title: GSM3375401: 293T_rep4_3N; Homo sapiens; OTHER
library_construction_protocol: TRIzol 3'READS: The 3'READS procedure has been described in (Zheng et al., 2016). Briefly, Poly(A)+ RNA in 0.1-15 µg of total RNA was captured using 10 µl of oligo(dT)25 magnetic beads in 100 µl 1x binding buffer (10 mM Tris-Cl, pH7.5, 150 mM NaCl, 1 mM EDTA, and 0.05% TWEEN 20) and fragmented on the beads using 1.5 U of RNase III in 30 µl RNase III buffer (10 mM Tris-Cl pH8.3, 60 mM NaCl, 10 mM MgCl2, and 1 mM DTT) at 37 °C for 15 min. After washing away unbound RNA fragments with binding buffer, poly(A)+ fragments were eluted from the beads with TE buffer (10 mM Tris-Cl, 1 mM EDTA, pH 7.5) and precipitated with ethanol, followed by ligation to 3 pmol of heat-denatured 5' adapter (5'-CCUUGGCACCCGAGAAUUCCANNNN) in the presence of 1 mM ATP, 0.1 µl of SuperaseIn, and 0.25 µl of T4 RNA ligase 1 in a 5 µl reaction at 22 °C for 1 h. The ligation products were captured by 10 pmol of biotin-T15-(+TT)5 attached to 12 µl of Dynabeads MyOne Streptavidin C1. After washing with washing buffer (10 mM Tris-Cl pH7.5, 1 mM NaCl, 1 mM EDTA, and 0.05% TWEEN 20), RNA fragments on the beads were incubated with 0.01 U/µl of RNase H at 37 °C for 30 min in 30 µl of RNase H buffer (50 mM Tris-Cl pH 7.5, 5 mM NaCl, 10 mM MgCl2, and 10 mM DTT). After washing with RNase H buffer, RNA fragments were eluted from the beads in elution buffer (1 mM NaCl, 1 mM EDTA, and 0.05% TWEEN 20) at 50 °C, precipitated with ethanol, and then ligated to 3 pmol of heat-denatured 5' adenylated 3' adapter (5'-rApp/NNNGATCGTCGGACTGTAGAACTCTGAAC/3ddC) with 0.25 µl T4 RNA ligase 2 (truncated KQ version) at 22 °C for 1 h in a 5 µl reaction containing 15% PEG 8000 and 0.2 µl of SuperaseIn. The ligation products were then precipitated and reverse transcribed using M-MLV reverse transcriptase, followed by PCR amplification using Phusion high-fidelity DNA polymerase and bar-coded PCR primers for 13-18 cycles (13 cycles for 5 µg input, 15 cycles for 1 µg input, and 18 cycles for inputs below 1 µg).   PCR products were size-selected twice with AMPure XP beads, using 0.6 volumes of beads (relative to the PCR reaction volume) to remove large DNA molecules and an additional 0.4 volumes of beads to remove small DNA molecules. The eluted DNA was selected again with 1 volume of AMPure XP beads to further remove small DNA molecules. The size and quantity of the libraries eluted from the AMPure beads were examined using a high sensitivity DNA kit on an Agilent Bioanalyzer. Libraries were sequenced on an Illumina NextSeq 500 (1x75 bases).
attributes.tag: GEO Accession
attributes.value: GSM3375401