TMEM216, a transmembrane protein localizing to the base of cilia, is crucial for primary ciliogenesis [2,6]. It is associated with the Hedgehog (Hh) signaling pathway, which is important in the development of primary cilia [2]. Mutations in TMEM216 are linked to ciliopathies, highlighting its biological importance in maintaining normal cellular functions [1,2,3,4,6]. Genetic models, such as zebrafish and mouse models, have been used to study its function [2,3,5,6].

Tmem216 -deficient mice had impaired Hh signaling and displayed ciliopathic phenotypes [2]. In zebrafish, tmem216 knockout led to photoreceptor degeneration, mislocalization of outer segment proteins, and abnormal outer segment disc morphology [3]. Additionally, mutations in TMEM216 in zebrafish caused gastrulation defects [6]. These loss-of-function experiments in different animal models reveal its role in cilia-related biological processes and disease conditions like ciliopathies and photoreceptor-related disorders.

In conclusion, TMEM216 is essential for primary ciliogenesis and proper Hh signaling. Its deficiency in KO models results in phenotypes related to ciliopathies and photoreceptor degeneration. The study of TMEM216 using these models helps in understanding the molecular mechanisms underlying ciliopathies and related diseases, providing insights for potential therapeutic strategies [2,3,6].

References:

1. McConnachie, Dominique J, Stow, Jennifer L, Mallett, Andrew J. 2020. Ciliopathies and the Kidney: A Review. In American journal of kidney diseases : the official journal of the National Kidney Foundation, 77, 410-419. doi:10.1053/j.ajkd.2020.08.012. https://pubmed.ncbi.nlm.nih.gov/33039432/

2. Wang, Yingying, Yao, Huili, Zhang, Yu, Su, Ling, Liu, Xiangguo. 2024. TMEM216 promotes primary ciliogenesis and Hedgehog signaling through the SUFU-GLI2/GLI3 axis. In Science signaling, 17, eabo0465. doi:10.1126/scisignal.abo0465. https://pubmed.ncbi.nlm.nih.gov/38261656/

3. Liu, Yu, Cao, Shuqin, Yu, Miao, Hu, Huaiyu. . TMEM216 Deletion Causes Mislocalization of Cone Opsin and Rhodopsin and Photoreceptor Degeneration in Zebrafish. In Investigative ophthalmology & visual science, 61, 24. doi:10.1167/iovs.61.8.24. https://pubmed.ncbi.nlm.nih.gov/32687549/

4. Malka, Samantha, Biswas, Pooja, Berry, Anne-Marie, Webster, Andrew R, Ayyagari, Radha. 2024. Substitution of a single non-coding nucleotide upstream of TMEM216 causes non-syndromic retinitis pigmentosa and is associated with reduced TMEM216 expression. In American journal of human genetics, 111, 2012-2030. doi:10.1016/j.ajhg.2024.07.020. https://pubmed.ncbi.nlm.nih.gov/39191256/

5. Wang, Jun, Thomas, Holly R, Thompson, Robert G, Perkins, Brian, Parant, John M. 2022. Variable phenotypes and penetrance between and within different zebrafish ciliary transition zone mutants. In Disease models & mechanisms, 15, . doi:10.1242/dmm.049568. https://pubmed.ncbi.nlm.nih.gov/36533556/

6. Valente, Enza Maria, Logan, Clare V, Mougou-Zerelli, Soumaya, Attié-Bitach, Tania, Gleeson, Joseph G. 2010. Mutations in TMEM216 perturb ciliogenesis and cause Joubert, Meckel and related syndromes. In Nature genetics, 42, 619-25. doi:10.1038/ng.594. https://pubmed.ncbi.nlm.nih.gov/20512146/