Fig. 5: Cdk12 controls mitochondrial morphology and peroxisome position.

A Mitochondrial morphology was observed at 21 days in wing sensory neuronal clones. Cdk12^−/− neurons and axonal swellings contain more spherical mitochondria compared to control, which was corrected with RNAi-mediated knockdown of Drp1 in axons. B Quantification shows that knockdown of the mitochondrial fission factor Drp1 caused an increase in mitochondrial aspect ratio in both wild-type and Cdk12 ablated axons. C Peroxisomes are largely confined to somato-dendritic regions in wild-type neurons at 1, 21, and 24 days, yet knock out of Cdk12 permitted age-dependent peroxisome entry into the proximal axon. D Peroxisomes in Cdk12^−/− axons were present in axonal swellings and non-swollen regions at 21 days. E Illustration to show that peroxisomes may be permitted to enter Cdk12 ablated and aged axons on actin filaments via attachment to myosin motor proteins. F Quantification shows that at 24 days there are significantly more peroxisomes present in Cdk12^−/− axonal clones compared to control, which can be rescued via RNAi-mediated knockdown of didum (Myosin V). Data was analyzed by two-way ANOVA and significant differences annotated as p < 0.05*, p < 0.01**, & p < 0.001*** between genotypes. Dashed lines define the soma-axon boundary, * define axonal swelling regions and arrows highlight axon localized peroxisomes. Graphs are expressed as Mean ± SEM and N = ≥ 8 wings for each group. Scale bars = 5 µm.