Integrator is involved in hTR transcription termination. (A) Total RNA prepared from HEK293T cells treated with siRNAs against the Integrator subunits INTS1, INTS9, and INTS11 was subjected to RT-qPCR to measure the levels of total hTR transcript (M + 3′) and the 3′-end-extended form of hTR (3′). The ratio of the level of the 3′-extended region of hTR to the total hTR level was calculated to compare the transcription termination and processing rate. Mean values were calculated from triplicate RT-qPCR experiments of three biological replicates, with bars representing the SE. The **** indicates P < 0,0001 by Sidak’s multiple comparisons test. (B) Schematic of the 3′-RACE approach used for 3′-end detection of the 3′-end-extended hTR transcript. (C,D) A histogram illustrating the distribution of the lengths of hTR-containing reads obtained for HEK293T cells expressing hTR under the control of the SFFV-promoter (C) and for HEK293T cells treated with siRNA targeting the INTS1 gene (D). The 3′-ends were determined using a RNA-ligase-mediated 3′-RACE approach, followed by pyrosequencing.