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Hum Mol Genet. 2014 Oct 1;23(19):5197-210. doi: 10.1093/hmg/ddu242. Epub 2014 May 15.

Disruption of the retinitis pigmentosa 28 gene Fam161a in mice affects photoreceptor ciliary structure and leads to progressive retinal degeneration.

Author information

1
Department of Ophthalmology, University of Cologne, Cologne, Germany.
2
Institute of Zoology, Johannes Gutenberg University of Mainz, Mainz, Germany.
3
Center for Experimental Molecular Medicine, University of Wuerzburg, Wuerzburg, Germany.
4
Institute of Human Anatomy and Embryology.
5
Department of Ophthalmology and.
6
Institute of Human Genetics, University of Regensburg, Regensburg, Germany.
7
Department of Ophthalmology, University of Cologne, Cologne, Germany, thomas.langmann@uk-koeln.de.

Abstract

Mutations in the FAM161A gene were previously identified as the cause for autosomal-recessive retinitis pigmentosa 28. To study the effects of Fam161a dysfunction in vivo, we generated gene-trapped Fam161a(GT/GT) mice with a disruption of its C-terminal domain essential for protein-protein interactions. We confirmed the absence of the full-length Fam161a protein in the retina of Fam161a(GT/GT) mice using western blots and showed weak expression of a truncated Fam161a protein by immunohistochemistry. Histological analyses demonstrated that photoreceptor segments were disorganized in young Fam161a(GT/GT) mice and that the outer retina was completely lost at 6 months of age. Reactive microglia appeared in the outer retina and electroretinography showed an early loss of photoreceptor function in 4-month-old Fam161a(GT/GT) animals. Light and electron microscopy revealed a remarkable phenotype of a significantly shortened connecting cilium, spread ciliary microtubule doublets and disturbed disk organization in Fam161a(GT/GT) photoreceptor cells. Co-immunolabeling experiments demonstrated reduced expression and mislocalization of centrin 3 and disturbed targeting of the Fam161a interactors lebercilin and Cep290, which were restricted to the basal body and proximal connecting cilium in Fam161a(GT/GT) retinas. Moreover, we identified misrouting of the outer segment cargo proteins opsin and rds/peripherin 2 in Fam161a(GT/GT) mice. In conclusion, our results suggest a critical role for the C-terminal domain of Fam161a for molecular interactions and integrity of the connecting cilium. Fam161a is required for the molecular delivery into the outer segment cilium, a function which is essential for outer segment disk formation and ultimately visual function.

PMID:
24833722
DOI:
10.1093/hmg/ddu242
[Indexed for MEDLINE]

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