Disruption of the retinitis pigmentosa 28 gene Fam161a in mice affects photoreceptor ciliary structure and leads to progressive retinal degeneration.
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.
Department of Ophthalmology, University of Cologne, Cologne, Germany.
Marcus
M
Karlstetter
Institute of Zoology, Johannes Gutenberg University of Mainz, Mainz, Germany.
Nasrin
N
Sorusch
Department of Ophthalmology, University of Cologne, Cologne, Germany.
Albert
A
Caramoy
Department of Ophthalmology, University of Cologne, Cologne, Germany.
Katharina
K
Dannhausen
Department of Ophthalmology, University of Cologne, Cologne, Germany.
Alexander
A
Aslanidis
Department of Ophthalmology, University of Cologne, Cologne, Germany.
Sascha
S
Fauser
Center for Experimental Molecular Medicine, University of Wuerzburg, Wuerzburg, Germany.
Michael R
MR
Boesl
Institute of Zoology, Johannes Gutenberg University of Mainz, Mainz, Germany.
Kerstin
K
Nagel-Wolfrum
Institute of Human Anatomy and Embryology.
Ernst R
ER
Tamm
Department of Ophthalmology and.
Herbert
H
Jägle
Institute of Human Genetics, University of Regensburg, Regensburg, Germany.
Heidi
H
Stoehr
Institute of Zoology, Johannes Gutenberg University of Mainz, Mainz, Germany.
Uwe
U
Wolfrum
Department of Ophthalmology, University of Cologne, Cologne, Germany, thomas.langmann@uk-koeln.de.
Thomas
T
Langmann
D000200:Action Potentials; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D018390:Gene Targeting; D056426:Genetic Loci; D005838:Genotype; D006801:Humans; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D017628:Microglia / Q000378:metabolism; D009154:Mutation; D010786:Photoreceptor Cells / Q000378:metabolism* / Q000473:pathology* / Q000648:ultrastructure; D011485:Protein Binding; D021381:Protein Transport; D012160:Retina / Q000378:metabolism; D012162:Retinal Degeneration / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D055213:Retinal Pigment Epithelium / Q000378:metabolism / Q000473:pathology; D014786:Vision Disorders / Q000235:genetics / Q000473:pathology / Q000503:physiopathology
D002352:Carrier Proteins; D005136:Eye Proteins; C552554:Fam161A protein, mouse