Changing affinities


The loss of functional primary cilia is associated with many debilitating diseases including the blinding disease Leber congential amaurosis (LCA) and Joubert syndrome, which is the result of an underdeveloped cerebellum. Mutations in the gene encoding the 290 kDA centrosomal protein (CEP290) have been identified in both diseases; however, very little is known about CEP290 function.  Theodore Drivas and colleagues at the University of Pennsylvania identified distinct domains of CEP290 that facilitate binding to cell membranes and microtubules. CEP290 activity was regulated by two autoinhibitory domains of the protein, which were critical for cilium formation. The authors determined that a previously described model of LCA, the rd16 mouse, produces a CEP290 protein lacking the microtubule-binding domain, and overexpression of two different truncated forms of CEP290 that lack the microtubule-binding domain resulted in localization to the cytosol. These data indicate that maintenance and regulation of both domains of this protein are required for proper localization and function. The above image is a composite fluorescence microscopy image of hTERT-RPE1 cells expressing truncations in CEP290 (GFP). Removal of the N-terminal microtubule-binding domain results in punctate staining, while removal of the cell membrane binding domain results in enhanced microtubule binding.

Published September 24, 2013, by Corinne Williams

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Disruption of CEP290 microtubule/membrane-binding domains causes retinal degeneration
Theodore G. Drivas, … , Erika L.F. Holzbaur, Jean Bennett
Theodore G. Drivas, … , Erika L.F. Holzbaur, Jean Bennett
Published September 24, 2013
Citation Information: J Clin Invest. 2013;123(10):4525-4539. https://doi.org/10.1172/JCI69448.
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Research Article Cell biology

Disruption of CEP290 microtubule/membrane-binding domains causes retinal degeneration

Abstract

Mutations in the gene centrosomal protein 290 kDa (CEP290) cause an array of debilitating and phenotypically distinct human diseases, ranging from the devastating blinding disease Leber congenital amaurosis (LCA) to Senior-Løken syndrome, Joubert syndrome, and the lethal Meckel-Gruber syndrome. Despite its critical role in biology and disease, very little is known about CEP290’s function. Here, we have identified 4 functional domains of the protein. We found that CEP290 directly binds to cellular membranes through an N-terminal domain that includes a highly conserved amphipathic helix motif and to microtubules through a domain located within its myosin-tail homology domain. Furthermore, CEP290 activity was regulated by 2 autoinhibitory domains within its N and C termini, both of which were found to play critical roles in regulating ciliogenesis. Disruption of the microtubule-binding domain in a mouse model of LCA was sufficient to induce significant deficits in cilium formation, which led to retinal degeneration. These data implicate CEP290 as an integral structural and regulatory component of the cilium and provide insight into the pathological mechanisms of LCA and related ciliopathies. Further, these data illustrate that disruption of particular CEP290 functional domains may lead to particular disease phenotypes and suggest innovative strategies for therapeutic intervention.

Authors

Theodore G. Drivas, Erika L.F. Holzbaur, Jean Bennett

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