Characterization of a Drosophila ortholog of SLC25A46 which is required for mitochondrial shaping during spermatogenesis
Mitochondria undergo various shape changes during Drosophila spermatogenesis, making this process useful for studying mitochondrial morphology. Abnormal mitochondrial clumping in late-stage spermatid elongation occurs in male flies with two mutant copies of CG5755. A unique stop codon mutation was identified in CG5755 after deficiency mapping of the Z2-3738 strain, tissue expression analysis, and sequencing of the only testis-specific gene within the candidate region. The nonsense mutation was absent from CG5755 in a different strain with the same background chromosome, confirming our gene. Crosses to trigger RNAi knockdown of CG5755 in testes produced males with wild type mitochondrial shaping, but since insufficient knockdown was a possibility, subsequent experiments are incorporating UAS-Dicer for an enhanced effect. We tested for genetic interactions between CG5755 and its broadly expressed paralog, CG8931. Male CG5755 heterozygotes that are hemizygous for a non-lethal insertion in CG8931 (X linked) are fertile, though the insertion may enhance the CG5755 homozygous phenotype. The human ortholog, SLC25A46, was found by other research groups to localize to the mitochondrial outer membrane, to interact with mitofilin, and to be associated with fusion/fission dynamics; SLC25A46 is associated with optic atrophy spectrum disorder and pontocerebellar hypoplasia.