Human CFEOM1 Mutations Attenuate KIF21A Autoinhibition and Cause Oculomotor Axon Stalling

• Published in: Neuron (Cambridge, Mass.) Vol. 82; no. 2; pp. 334 - 349
• Main Authors: Cheng, Long, Desai, Jigar, Miranda, Carlos J., Duncan, Jeremy S., Qiu, Weihong, Nugent, Alicia A., Kolpak, Adrianne L., Wu, Carrie C., Drokhlyansky, Eugene, Delisle, Michelle M., Chan, Wai-Man, Wei, Yan, Propst, Friedrich, Reck-Peterson, Samara L., Fritzsch, Bernd, Engle, Elizabeth C.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 16.04.2014; Elsevier Limited
• Subjects: Age Factors; Animals; Animals, Newborn; Axons - pathology; Axons - ultrastructure; Cell Count; Disease Models, Animal; Embryo, Mammalian; Experiments; Eye Diseases, Hereditary - genetics; Eye Diseases, Hereditary - pathology; Eye Diseases, Hereditary - physiopathology; Eye Movements - genetics; Eye Movements - physiology; Fibrosis - genetics; Fibrosis - pathology; Fibrosis - physiopathology; Gene Expression Regulation - genetics; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; HEK293 Cells; Humans; Kinesins - genetics; Kinesins - metabolism; Mice; Mice, Transgenic; Microtubule-Associated Proteins - genetics; Microtubule-Associated Proteins - physiology; Motility; Mutation; Mutation - genetics; Neural Pathways - metabolism; Neural Pathways - pathology; Neural Pathways - ultrastructure; Neurons; Neurosciences; Ocular Motility Disorders - genetics; Ocular Motility Disorders - pathology; Ocular Motility Disorders - physiopathology; Oculomotor Nerve - pathology; Oculomotor Nerve - ultrastructure; Pathogenesis; Pathology; Proteins; Rodents
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/j.neuron.2014.02.038

The ocular motility disorder “Congenital fibrosis of the extraocular muscles type 1” (CFEOM1) results from heterozygous mutations altering the motor and third coiled-coil stalk of the anterograde kinesin, KIF21A. We demonstrate that Kif21a knockin mice harboring the most common human mutation develop CFEOM. The developing axons of the oculomotor nerve’s superior division stall in the proximal nerve; the growth cones enlarge, extend excessive filopodia, and assume random trajectories. Inferior division axons reach the orbit but branch ectopically. We establish a gain-of-function mechanism and find that human motor or stalk mutations attenuate Kif21a autoinhibition, providing in vivo evidence for mammalian kinesin autoregulation. We identify Map1b as a Kif21a-interacting protein and report that Map1b−/− mice develop CFEOM. The interaction between Kif21a and Map1b is likely to play a critical role in the pathogenesis of CFEOM1 and highlights a selective vulnerability of the developing oculomotor nerve to perturbations of the axon cytoskeleton. •CFEOM1-KIF21A mutations cause ocular dysmotility through a gain-of-function mechanism•Developing Kif21a mutant oculomotor axons stall and form aberrant nerve branches•CFEOM1-Kif21a mutations provide in vivo evidence of mammalian kinesin autoregulation•Kif21a interacts with Map1b and Map1b−/− mice also develop CFEOM CFEOM1 is a congenital eye movement disorder caused by recurrent mutations in widely expressed KIF21A. Cheng et al. report that CFEOM1 mutations are gain of function, attenuating Kif21a autoinhibition, enhancing Kif21a-microtubule association, and perturbing oculomotor nerve development in vitro and in vivo.