Defective neurite elongation and branching in Nibp/Trappc9 deficient zebrafish and mice.

International journal of biological sciences 2023

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Loss of function in transport protein particles (TRAPP) links a new set of emerging genetic disorders called "TRAPPopathies". One such disorder is NIBP syndrome, characterized by microcephaly and intellectual disability, and caused by mutations of NIBP/TRAPPC9, a crucial and unique member of TRAPPII. To investigate the neural cellular/molecular mechanisms underlying microcephaly, we developed Nibp/Trappc9-deficient animal models using different techniques, including morpholino knockdown and CRISPR/Cas mutation in zebrafish and Cre/LoxP-mediated gene targeting in mice. Nibp/Trappc9 deficiency impaired the stability of the TRAPPII complex at actin filaments and microtubules of neurites and growth cones. This deficiency also impaired elongation and branching of neuronal dendrites and axons, without significant effects on neurite initiation or neural cell number/types in embryonic and adult brains. The positive correlation of TRAPPII stability and neurite elongation/branching suggests a potential role for TRAPPII in regulating neurite morphology. These results provide novel genetic/molecular evidence to define patients with a type of non-syndromic autosomal recessive intellectual disability and highlight the importance of developing therapeutic approaches targeting the TRAPPII complex to cure TRAPPopathies. © The author(s).

Citation

Min Hu, Brittany Bodnar, Yonggang Zhang, Fangxin Xie, Fang Li, Siying Li, Jin Zhao, Ruotong Zhao, Naveen Gedupoori, Yifan Mo, Lanyi Lin, Xue Li, Wentong Meng, Xiaofeng Yang, Hong Wang, Mary F Barbe, Shanthi Srinivasan, John R Bethea, Xianming Mo, Hong Xu, Wenhui Hu. Defective neurite elongation and branching in Nibp/Trappc9 deficient zebrafish and mice. International journal of biological sciences. 2023;19(10):3226-3248