Objective: Characterization of isogenic CHCHD2, CHCHD10, and CHCHD2/10 double knockout out cell lines with assays of mitochondrial function, mitochondrial sublocalization, and homo- and heterodimerization.

Background: Mutations in paralogous mitochondrial proteins CHCHD2 and CHCHD10 were recently found to cause autosomal dominant Parkinson Disease (PD) and ALS/FTD, respectively. The proteins exhibit 58% amino acid sequence identity and are thought to have resulted from a gene duplication event. Additionally, most pathogenically proven missense mutations in CHCHD2 (including T61I) and CHCHD10 (including G58R, S59L, and G66V) cluster in the same highly conserved region. The extent to which the proteins have retained a common function in their divergent evolution, however, is not known. To this end, we generated CHCHD2 KO, CHCHD10 KO, and CHCHD2/10 double KO cells on an isogenic background to allow direct comparison of CHCHD2 and CHCHD10 localization and function.

Methods: Isogenic CHCHD2, CHCHD10, and CHCHD2/10 double knockout cell lines were generated on a HEK293 and HeLa cell background by Crispr/Cas9. Localization was assessed using confocal, stimulated emission depletion (STED), and immuno-electron microscopy. Mitochondrial protein expression was assessed by immunoblotting and mitochondrial function was assessed using the Seahorse oxygen consumption assay. Homo- and heterodimerization of CHCHD2 and CHCHD10 was assessed in co-immunoprecipitation and crosslinking studies.

Results: We find that CHCHD2 and CHCHD10 are partially functionally redundant, share localization throughout mitochondrial cristae, and form heterodimers. CHCHD2 is strictly required for oligomerization of CHCHD10. CHCHD2, in contrast to CHCHD10, readily forms homodimers in the absence of CHCHD10, which may account for the more severe phenotype resulting from loss of CHCHD2. We exploit the dependence of CHCHD10 oligomerization on CHCHD2 to develop a CHCHD2/CHCHD10 heterodimer incorporation assay and demonstrate that CHCHD2 and CHCHD10 with disease-causing mutations readily incorporate into heterodimers.

Conclusions: CHCHD2 and CHCHD10 have retained a similar function and directly interact. Notably, CHCHD10 is dependent on CHCHD2 for oligomerization. Disease-causing mutations do not disrupt the direct interaction of CHCHD2 and CHCHD10 and suggest a mechanism by which pathogenic mutations in CHCHD2 could directly affect functioning of wildtype CHCHD10 and vice versa.

« Back to 2018 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/parkinson-related-chchd2-is-necessary-for-oligomerization-of-als-ftd-related-chchd10/