Combining Cep290 and Mkks ciliopathy alleles in mice rescues sensory defects and restores ciliogenesis
Rivka A. Rachel, … , Matthew W. Kelley, Anand Swaroop
Rivka A. Rachel, … , Matthew W. Kelley, Anand Swaroop
Published March 26, 2012
Citation Information: J Clin Invest. 2012;122(4):1233-1245. https://doi.org/10.1172/JCI60981.
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Research Article

Combining Cep290 and Mkks ciliopathy alleles in mice rescues sensory defects and restores ciliogenesis

Abstract

Cilia are highly specialized microtubule-based organelles that have pivotal roles in numerous biological processes, including transducing sensory signals. Defects in cilia biogenesis and transport cause pleiotropic human ciliopathies. Mutations in over 30 different genes can lead to cilia defects, and complex interactions exist among ciliopathy-associated proteins. Mutations of the centrosomal protein 290 kDa (CEP290) lead to distinct clinical manifestations, including Leber congenital amaurosis (LCA), a hereditary cause of blindness due to photoreceptor degeneration. Mice homozygous for a mutant Cep290 allele (Cep290rd16 mice) exhibit LCA-like early-onset retinal degeneration that is caused by an in-frame deletion in the CEP290 protein. Here, we show that the domain deleted in the protein encoded by the Cep290rd16 allele directly interacts with another ciliopathy protein, MKKS. MKKS mutations identified in patients with the ciliopathy Bardet-Biedl syndrome disrupted this interaction. In zebrafish embryos, combined subminimal knockdown of mkks and cep290 produced sensory defects in the eye and inner ear. Intriguingly, combinations of Cep290rd16 and Mkksko alleles in mice led to improved ciliogenesis and sensory functions compared with those of either mutant alone. We propose that altered association of CEP290 and MKKS affects the integrity of multiprotein complexes at the cilia transition zone and basal body. Amelioration of the sensory phenotypes caused by specific mutations in one protein by removal of an interacting domain/protein suggests a possible novel approach for treating human ciliopathies.

Authors

Rivka A. Rachel, Helen L. May-Simera, Shobi Veleri, Norimoto Gotoh, Byung Yoon Choi, Carlos Murga-Zamalloa, Jeremy C. McIntyre, Jonah Marek, Irma Lopez, Alice N. Hackett, Matthew Brooks, Anneke I. den Hollander, Philip L. Beales, Tiansen Li, Samuel G. Jacobson, Raman Sood, Jeffrey R. Martens, Paul Liu, Thomas B. Friedman, Hemant Khanna, Robert K. Koenekoop, Matthew W. Kelley, Anand Swaroop

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Figure 3

Knockdown by coinjection of subminimal doses of cep290 and mkks morpholinos causes sensory defects in zebrafish embryos.

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Knockdown by coinjection of subminimal doses of cep290 and mkks morpholi...
(A) Whole mount embryos at 72 hours after fertilization. Subminimal doses of morpholinos against cep290 and mkks transcripts and standard negative control (SNC) produced no phenotype, whereas coinjecting subminimal doses of mkks and cep290 resulted in deformed eyes (yellow circles) and ears (red ovals). Original magnification, ×11.5. (B) H&E-stained sections of eyecups and otocysts in control (0.5 ng cep290 plus 1.0 ng SNC) and experimental (0.5 ng cep290 plus 1.0 ng mkks) embryos. Note the lack of normal lens formation and retinal lamination in the double morphant embryos (top panel) and impaired tether cell development in the otocyst (bottom panel). Original magnification, ×60. (C) Quantitation of morphant phenotypes. Subminimal doses of cep290 or mkks morpholino alone resulted in abnormal embryos at a frequency similar to that of uninjected controls (<5%), whereas combining both morpholinos yielded 18% of embryos with ear, eye, and/or axis defects. Higher doses of either morpholino alone revealed a greater percentage of defective embryos, consistent with previous results (27, 43, 44). Eye or ear defects were never observed in uninjected embryos. Error bars are SD. Numbers of embryos examined per condition are 245 (uninjected), 53 (0.5 ng cep290 plus 1.0 ng SNC), 121 (0.5 ng mkks plus 1.0 ng SNC), 208 (0.5 ng cep290 plus 1.0 ng mkks), 98 (1.0 ng cep290), 125 (2.0 ng cep290), and 55 (2.0 ng mkks).