Fig. 4. Chchd2 modulates the levels of Opa1.

The relative mRNA levels of Marf, Drp1, and Opa1 in wild type (WT) and Chchd2^8-8 mutants were measured by real-time PCR. Opa1 mRNA level was significantly decreased in Chchd2^8-8 mutants. The experiment has been repeated 3 times. The data were presented as mean + SEM. ***p < 0.001. b, b’ The protein levels of Opa1 were decreased in Chchd2^8-8 mutants. The endogenous levels of Opa1 were measured through examine the 3 × HA Opa1 knock in animals. Tubulin levels were examined as a loading control. b’ is the quantification of b. The experiment has been repeated 3 times. The data were presented as mean + SEM. ***p < 0.001. c, c' Chchd2 overexpression stabilized Opa1 in a dose dependent manner. Same amount of DNA encoding 3 × HA tagged Opa1 was co-expressed with increased amount of DNA encoding Chchd2 in S2 cells. Tubulin levels were examined as a loading control. c’ is the quantification of c. The experiment has been repeated 3 times. The data were presented as mean + SEM. ***p < 0.001. d Chchd2 and Opa1 did not pull down each other in the immunoprecipitation experiments. e, e’ Overexpression of YME1L reduced the levels of Opa1, whereas co-expression of Chchd2 could counteract this effect. e’ is the quantification of e. The experiment has been repeated 3 times. The data were presented as mean + SEM. ***p < 0.001. f Chchd2 and YME1L did not pull down each other in the immunoprecipitation experiments. g A list of C1QBP peptides that were identified by immunoprecipitation with anti-human CHCHD2 antibody followed by mass spectrometry. h Overexpressed V5-tagged C1QBP could pull down endogenous CHCHD2 in Hela cells. i V5-tagged fly Chchd2 proteins could pull down HA-tagged P32 when both were overexpressed in S2 cells. j–l Chchd2 and P32 were colocalized in S2 cells. The nuclei were marked with DAPI staining (blue). The bar indicates 5 μm.