Downregulation of the Mitochondrial Phosphatase PTPMT1 Is Sufficient to Promote Cancer Cell Death
Figure 1
RNAi-mediated downregulation of PTPMT1 induces cell death in HeLa cells.
(A) Quantitative RT-PCR analysis of PTPMT1 mRNA levels in HeLa cells after knockdown with two non-overlapping PTPMT1-specfic siRNAs or a non-targeting control. (B) HeLa cells were transfected with two PTPMT1 siRNAs or a non-targeting control for 48 hr. In one experiment, PTPMT1 was overexpressed (with a FLAG-tag) for 20 hr (total siRNA transfection time 48 hr) and expression was probed with a FLAG antibody (top panel). siRNA knock down was also determined for endogenous PTPMT1 (middle panel). Tubulin (bottom panel) demonstrates equal loading of protein lysates in all lanes. (C–E) HeLa cells were transfected with control or PTPMT1 siRNAs and collected after indicated times, at which cell death was assayed by propidium iodide exclusion. Error bars indicate standard deviation of three experiments. Statistical significance was calculated using a student’s t test; * - p<0.05; ** - p<0.01; *** - p<0.001. (F) HeLa cells were transfected with control or PTPMT1 siRNAs and assayed for viability in real time (>120 hours) using the xCELLigence system.