Figure 2.

MIA40 overexpression ameliorates ETC deficiency in Hq MEFs. (a and b) Immunoblot and densitometry analysis of AIF, MIA40, NDUFB7 (CI), mitochondrially encoded cytochrome c oxidase I (CIV), SDHB (CII), CHCHD4/MIA40, myc-tagged CHCHD4/MIA40 and tubulin in wt and Hq MEFs transiently transfected with mitochondria-targeted green fluorescent protein (−) or MIA40-myc (+) plasmids. Endogenous CHCHD4/MIA40 (<) and myc-tagged CHCHD4/MIA40 (<<) are indicated. Values are plotted as means (+S.D.) and represent fold difference relative to control conditions. Asterisks show statistical significance (One-way ANOVA with Tukey's multiple comparisons test **P<0.01, *P<0.05, NS, non-significant). (c) Schematic representation of a simplified proposed working model. MIA40 substrates, such as CI subunits and CIV assembly factors are imported into mitochondria via the TOM complex. MIA40 binding to AIF results in efficient oxidative protein folding and ETC assembly