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.
View: Text | PDF | Corrigendum
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

×

Figure 6

Loss of MKKS in combination with CEP290-DSD rescues hair cell kinocilia and olfactory sensory cilia defects.

Options: View larger image (or click on image) Download as PowerPoint
Loss of MKKS in combination with CEP290-DSD rescues hair cell kinocilia ...
(A) Confocal images of stereociliary bundles of hair cells from P0 mice. Minor defects in stereociliary bundle architecture in Cep290rd16/rd16 mice compared with those in P0 WT mice and marked defects in bundle morphology in Mkksko/ko mice (blue circles). Bundle morphology is normal in double mutants (white arrow). Original magnification, ×75.6. (B) Higher-magnification image (original magnification, ×116) of phalloidin-labeled stereocilia bundles (red) and acetyl-α-tubulin–marked kinocilia (green) of outer hair cells in P0 cochlea. In the adjacent monochromatic panel, red lines identify kinocilia. Abnormal bundle rotation and misplaced, malformed, or missing kinocilia in Mkksko/ko cells are rescued in the double mutant (white arrows). (C) Quantitation of kinocilium length. Cep290rd16/rd16 cilia are significantly longer than WT cilia; Mkksko/ko kinocilia are highly abnormal or absent; double-mutant kinocilia are indistinguishable from WT kinocilia. ND, not determined. Error bars are SD; kinocilia measured, respectively, are n = 42 (WT), n = 77 (Cep290rd16/rd16), and n = 35 (Cep290rd16/rd16;Mkksko/ko). (D) ABRs in 3- to 4-month-old mice of indicated genotypes, with mean threshold ± SD. Mkksko/ko and Cep290rd16/rd16 mice show elevated hearing thresholds. Complete rescue of ABR thresholds in animals with triallelic combinations and partial rescue in double homozygotes. Error bars are SD; cochlea examined for each condition, respectively, are n = 8 (WT), n = 8 (Cep290rd16/rd16), n = 18 (Cep290rd16/rd16;Mkksko/+), n = 6 (Mkksko/ko), n = 6 (Cep290rd16/+;Mkksko/ko), and n = 6 (Cep290rd16/rd16;Mkksko/ko). (E) SEM images of olfactory epithelium at 7 to 8 weeks of age, showing loss of cilia in Mkksko/ko mice (small white arrow) and their retention in the double-mutant and triple allelic combinations (large white arrow). Original magnification, ×6,500.