Tbc1d23, a member of the Tre2-Bub2-Cdc16 (TBC) family, is a Golgi-localized protein [3,4,6]. It plays essential roles in multiple biological processes, mainly in membrane trafficking, especially endosome-to-Golgi trafficking. It also has a significant association with the LKB1-AMPK signaling axis. Genetic models, such as zebrafish, are valuable for studying Tbc1d23 due to the conserved functions across species [1,2,5].

In zebrafish models, depletion of Tbc1d23 leads to developmental defects similar to those seen in pontocerebellar hypoplasia (PCH) patients [2,5,6]. Tbc1d23 directly interacts with LKB1, recruiting it to the Golgi and promoting Golgi-specific activation of AMPK upon energy stress. Golgi-targeted expression of LKB1 can rescue Tbc1d23 deficiency in zebrafish [1]. Also, Tbc1d23 interacts with FAM91A1, and their cooperation regulates endosome-to-Golgi trafficking of KIAA0319L, a protein for axonal growth [2]. In addition, Tbc1d23 acts as a bridging factor for endosomal vesicle capture by golgins at the trans-Golgi, and its mutations affect dense core vesicles and lysosomal trafficking dynamics in fibroblasts [4,7].

In conclusion, Tbc1d23 is crucial for endosome-to-Golgi trafficking and LKB1-AMPK signaling at the Golgi. Studies using zebrafish models have revealed its role in neurodevelopmental processes, especially in relation to PCH. Understanding Tbc1d23 provides insights into the molecular mechanisms underlying PCH and potentially other neurodevelopmental disorders.

References:

1. Tu, Yingfeng, Yang, Qin, Tang, Min, Dai, Lunzhi, Jia, Da. 2024. TBC1D23 mediates Golgi-specific LKB1 signaling. In Nature communications, 15, 1785. doi:10.1038/s41467-024-46166-2. https://pubmed.ncbi.nlm.nih.gov/38413626/

2. Zhao, Lin, Deng, Huaqing, Yang, Qing, Billadeau, Daniel D, Jia, Da. 2023. FAM91A1-TBC1D23 complex structure reveals human genetic variations susceptible for PCH. In Proceedings of the National Academy of Sciences of the United States of America, 120, e2309910120. doi:10.1073/pnas.2309910120. https://pubmed.ncbi.nlm.nih.gov/37903274/

3. Liu, Dingdong, Yang, Fan, Liu, Zhe, Mo, Xianming, Jia, Da. 2020. Structure of TBC1D23 N-terminus reveals a novel role for rhodanese domain. In PLoS biology, 18, e3000746. doi:10.1371/journal.pbio.3000746. https://pubmed.ncbi.nlm.nih.gov/32453802/

4. Shin, John J H, Gillingham, Alison K, Begum, Farida, Chadwick, Jessica, Munro, Sean. 2017. TBC1D23 is a bridging factor for endosomal vesicle capture by golgins at the trans-Golgi. In Nature cell biology, 19, 1424-1432. doi:10.1038/ncb3627. https://pubmed.ncbi.nlm.nih.gov/29084197/

5. Huang, Wenjie, Liu, Zhe, Yang, Fan, Mo, Xianming, Jia, Da. 2019. Structural and functional studies of TBC1D23 C-terminal domain provide a link between endosomal trafficking and PCH. In Proceedings of the National Academy of Sciences of the United States of America, 116, 22598-22608. doi:10.1073/pnas.1909316116. https://pubmed.ncbi.nlm.nih.gov/31624125/

6. Marin-Valencia, Isaac, Gerondopoulos, Andreas, Zaki, Maha S, Barr, Francis A, Gleeson, Joseph G. 2017. Homozygous Mutations in TBC1D23 Lead to a Non-degenerative Form of Pontocerebellar Hypoplasia. In American journal of human genetics, 101, 441-450. doi:10.1016/j.ajhg.2017.07.015. https://pubmed.ncbi.nlm.nih.gov/28823706/

7. Ivanova, Ekaterina L, Mau-Them, Frédéric Tran, Riazuddin, Saima, van Bokhoven, Hans, Chelly, Jamel. 2017. Homozygous Truncating Variants in TBC1D23 Cause Pontocerebellar Hypoplasia and Alter Cortical Development. In American journal of human genetics, 101, 428-440. doi:10.1016/j.ajhg.2017.07.010. https://pubmed.ncbi.nlm.nih.gov/28823707/