Oma1 deletion in Phb2^NKO mice is neuroprotective. (A) Loss of OMA1 prolongs the lifespan of Phb2^NKO mice. Kaplan–Meier survival plot of Phb2^NKO (n = 15), Phb2^NKOOma1^ko/ko (n = 28), and Phb2^fl/fl animals (n = 30). ****, P < 0.0001. (B) Deletion of Oma1 in Phb2^NKO mice prevents brain atrophy. Representative photographs of brains isolated from 18-wk-old mice. Bar, 2 mm. (C) Brain weights were monitored at 18 wk of age (Phb2^fl/fl, n = 10; Phb2^NKO, n = 7; Oma1^ko/ko, n = 9; Phb2^NKOOma1^ko/ko, n = 14). ***, P < 0.001. Error bars indicate SD. (D) Oma1 ablation in Phb2^NKO mice improves neuronal survival. Number of DG neurons in 14- and 18-wk-old mice of the indicated genotypes (n = 3). **, P < 0.01; ***, P < 0.001. Error bars indicate SD. (E) Coronal semithin sections of the hippocampal DG from 14- and 18-wk-old mice. Black vertical bars show the thickness of the neuronal layers. Bars, 50 µm.