A new mouse model for Fam161a-associated retinal ciliopathy

Abstract

Purpose: Retinitis Pigmentosa (RP) is an inherited retinal degenerative disease leading to progressive vision loss. Nonsense mutations in the photoreceptor-specific Fam161a gene causes RP-28 associated autosomal-recessive RP. Recent studies have shown that Fam161a is a ciliary protein and critically involved in microtubule formation. The goal of this study was the generation of a Fam161a-deficient mouse line to study pathomechanisms involving Fam161a deficiency in the murine retina.

Methods: Fam161a gene trap mice were generated from UPA-vector targeted embryonic stem cells derived from the Canadian mouse mutant repository. Genomic locus and orientation of the gene trap in embryonic stem cells were confirmed by sanger sequencing of genomic DNA. Germline transmission of the gene trap was analyzed by PCR-based genotyping and Fam161a expression was studied by qRT-PCR in various tissues. The retinal morphology of Fam161a-deficient mice was analyzed by optical coherence tomography (OCT) and immunohistochemistry.

Results: We could confirm a unique gene trap insertion in exon 3 of the Fam161a gene resulting in nonsense mediated mRNA decay. The gene trap was successfully transmitted to the germline of chimeric founder animals and was also detected in all offspring animals. OCT-phenotyping of Fam161a-deficient retinas revealed significant thinning of the retina compared to age-matched littermates. A further detailed temporal histological analysis of Fam161a-deficient retinas showed complete loss of the outer retinal layers in 6 month old animals.

Conclusions: In this study we generated and characterized a novel Retinitis Pigmentosa mouse model with Fam161a deficiency. This model could be a useful tool to study Fam161a-associated retinal ciliopathy.

Keywords: 696 retinal degenerations: hereditary • 702 retinitis • 539 genetics