Gadd45a-null mice generated by gene targeting exhibited several of the phenotypes characteristic of p53-deficient mice, including genomic instability, increased radiation carcinogenesis and a low frequency of exencephaly. Genomic instability was exemplified by aneuploidy, chromosome aberrations, gene amplification and centrosome amplification, and was accompanied by abnormalities in mitosis, cytokinesis and growth control. Unequal segregation of chromosomes due to multiple spindle poles during mitosis occurred in several Gadd45a -/- cell lineages and may contribute to the aneuploidy. Our results indicate that Gadd45a is one component of the p53 pathway that contributes to the maintenance of genomic stability.

The mitochondrial inner membrane contains a large protein complex that functions in inner membrane organization and formation of membrane contact sites. The complex was variably named the mitochondrial contact site complex, mitochondrial inner membrane organizing system, mitochondrial organizing structure, or Mitofilin/Fcj1 complex. To facilitate future studies, we propose to unify the nomenclature and term the complex “mitochondrial contact site and cristae organizing system” and its subunits Mic10 to Mic60.

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Background: Functional characterization of a novel mitochondrial protein, CHCM1/CHCHD6, is reported. Results: CHCM1 interacts with Mitofilin, DISC1, and CHCHD3, and its deficiency leads to severe defects in mitochondrial cristae morphology, reduction in cell growth, ATP production, and oxygen consumption. Conclusion: CHCM1/CHCHD6 is a novel player linked to mitochondrial cristae morphology. Significance: Results provide valuable insights into molecular events controlling the structural integrity and biogenesis of mitochondrial cristae.

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