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. 2018 May 7;217(5):1601–1611. doi: 10.1083/jcb.201801168

Figure 4.

Figure 4.

Exonuclease activity of POLG regulates mtDNA copy number in WT and is required for mtDNA degradation in autophagy mutants during starvation. (A and B) mtDNA synthesis is unaffected by exonuclease-activity of POLG. POLG, Δatg7 POLG, polgexo−, and Δatg7 polgexo− cells were treated as described in Fig. 1 A. Data are means ± SD (n ≥ 3; 150 cells). (C–E) Exonuclease-deficiency of POLG rescues mtDNA maintenance in autophagy-deficient cells during starvation. POLG, Δatg7 POLG, polgexo−, and Δatg7 polgexo− cells were grown and analyzed as described in Fig. 1 (C–E). Data are means ± SD (n = 3; ≥75 cells). (F) Exonuclease deficiency of POLG prevents decrease in mtDNA copy number during starvation. POLG, Δatg7 POLG, polgexo−, and Δatg7 polgexo− cells were analyzed as described in Fig. 1 F. Data are means ± SD (n = 3). Dashed lines indicate cell boundaries. Bars, 2 µm. t tests: *, P < 0.05; **, P < 0.01; ***, P < 0.001; n.s., not significant. Rel., relative.