Fam161a is a gene encoding a novel centrosomal-ciliary protein. It is essential for the structure of the photoreceptor connecting cilium (CC) in the retina [1,2]. The protein localizes to the connecting cilium, basal body, adjacent centriole in mammalian photoreceptors, as well as in synaptic layers and ganglion cells of the retina. It is part of microtubule-organizing centers in cultured cells, associates with the intracellular microtubule network, directly binds to microtubules and increases the acetylation of α-tubulin [1].

A Fam161a knockout (KO) mouse model, Fam161atm1b/tm1b, lacking the major exon #3, shows a gradual decrease in visual acuity and electroretinographic (ERG) responses between 1-8 months of age. Optical coherence tomography (OCT) reveals thinning of the whole retina, and histological analysis shows progressive photoreceptor degeneration. High-resolution transmission electron microscopy (TEM) shows disorganized photoreceptor outer segment disks. Molecular degenerative markers appear in 1-month old KO retinas [3]. In another study, gene augmentation therapy in Fam161a knockout mice using an adeno-associated virus encoding for the longer transcript of mFam161a led to significant structural and functional rescue of the retina [4].

In conclusion, Fam161a is crucial for maintaining the structure and function of the photoreceptor connecting cilium in the retina. The Fam161a KO mouse models have been instrumental in understanding the role of this gene in retinal degeneration, specifically in retinitis pigmentosa. These models also provide a basis for developing gene augmentation therapies for diseases caused by Fam161a deficiency [3,4].

References:

1. Zach, Frank, Stöhr, Heidi. . FAM161A, a novel centrosomal-ciliary protein implicated in autosomal recessive retinitis pigmentosa. In Advances in experimental medicine and biology, 801, 185-90. doi:10.1007/978-1-4614-3209-8_24. https://pubmed.ncbi.nlm.nih.gov/24664697/

2. Arsenijevic, Yvan, Chang, Ning, Mercey, Olivier, Hamel, Virginie, Kostic, Corinne. 2024. Fine-tuning FAM161A gene augmentation therapy to restore retinal function. In EMBO molecular medicine, 16, 805-822. doi:10.1038/s44321-024-00053-x. https://pubmed.ncbi.nlm.nih.gov/38504136/

3. Beryozkin, Avigail, Matsevich, Chen, Obolensky, Alexey, Banin, Eyal, Sharon, Dror. 2021. A new mouse model for retinal degeneration due to Fam161a deficiency. In Scientific reports, 11, 2030. doi:10.1038/s41598-021-81414-1. https://pubmed.ncbi.nlm.nih.gov/33479377/

4. Matsevich, Chen, Gopalakrishnan, Prakadeeswari, Chang, Ning, Arsenijevic, Yvan, Banin, Eyal. 2023. Gene augmentation therapy attenuates retinal degeneration in a knockout mouse model of Fam161a retinitis pigmentosa. In Molecular therapy : the journal of the American Society of Gene Therapy, 31, 2948-2961. doi:10.1016/j.ymthe.2023.08.011. https://pubmed.ncbi.nlm.nih.gov/37580905/