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. 2004 May 7;5(6):626–631. doi: 10.1038/sj.embor.7400154

Figure 1.

Figure 1

Silencing of Sgt1 affects progression through mitosis. (A) Western blot of HeLa cell lysates harvested at the indicated time points after transfection with siRNA duplexes against Sgt1. Control injections of anti-luciferase (Luc) siRNAs are also shown. Both splicing isoforms of Sgt1 are silenced. (B) DNA content was analysed by FC on PIstained cells. Cells lacking Sgt1 accumulate with 4N DNA, with an increase in a sub-G1 population 96-h after siRNA transfection. (C) A cell (white arrowhead) lacking Sgt1 enters mitosis and remains arrested for several hours, finally exiting without dividing. This cell eventually died around 75 h. (D) Trivariate FC analysis of cells lacking Sgt1. White bars: Cells with 4N DNA content; grey bars: cells with 4N DNA content that were H3-P positive (mitotic cells, M); black bars: cells with 4N DNA content that were positive for Cyclin B1 (total of G2- and M-phase cells). Note the increase of H3-P-positive cells following Sgt1 depletion, with a concomitant modest increase in G2–M cells at 72 h. More than 20% of the cell population had 4N DNA content but stained negative for mitotic markers, indicative of a tetraploid G1 population.