Fig 2: PDZRN3 depletion down-regulates Mre11, activates p53, and enhances serum deprivation-induced DNA damage. (a,b,e) C2C12 myoblasts infected with adenoviruses for PDZRN3 (KD or KD*) or scrambled (Scramb) shRNAs were incubated in low-serum medium for the indicated times and then subjected to immunoblot analysis with antibodies to Mre11 (a), to Ser15-phosphorylated p53 (p-p53) (b), to Ser139-phosphorylated H2AX (p-H2AX) (e), or to α-tubulin (loading control). Representative blots as well as quantitative data (means ± s.e.m. for 10 biological replicates) for the abundance of Mre11, p-p53, and p-H2AX normalized by that of α-tubulin and expressed relative to the value for Scramb at time 0 (a,b) or 12 h (e) are shown. *P < 0.05, **P < 0.01, ***P < 0.001 (two-way ANOVA). (c) The cells in (b) were also subjected to immunoblot analysis with antibodies to p53 and to α-tubulin after serum deprivation for 12 h. The abundance of total p53 protein was normalized by that of α-tubulin and is expressed relative to the value for Scramb. Data are means ± s.e.m. from nine biological replicates. ***P < 0.001 (unpaired Student’s t test). (d) C2C12 cells infected or not (None) with adenoviruses encoding PDZRN3 (KD or KD*) or scrambled (Scramb) shRNAs were subjected to immunofluorescence analysis with antibodies to p-H2AX after serum deprivation for 6 h. Nuclei were stained with DAPI. Scale bars, 25 μm. Arrowheads indicate foci of p-H2AX formed in nuclei in response to DNA damage.