{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nTRAPPC9 (also known as NIBP) is emerging as a critical mediator in brain development, with its disruption linked to intellectual disability and microcephaly. Mutations in TRAPPC9 have been shown to impair NF‑κB activation and intracellular protein trafficking in postmitotic neurons, thereby compromising axonal connectivity and proper neuronal differentiation. These findings indicate that TRAPPC9 is essential for establishing and maintaining the complex neuronal circuits required for normal cognitive function."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": "\n \nDisruption of membrane trafficking also appears to be a central mechanism underlying TRAPPC9’s function. Acting as a subunit of the TRAPPII complex, TRAPPC9 is involved in the regulation of vesicle tethering between the endoplasmic reticulum and the Golgi apparatus through the activation of Rab1. In related studies, molecules such as IBP exemplify how dysregulation of GTPase signaling and actin dynamics may impact cellular functions, underscoring the broader relevance of vesicular and cytoskeletal regulation in health and disease."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": "\n \nMoreover, TRAPPC9 contributes to cytoskeletal organization and the regulation of organelle dynamics in a cell type–dependent manner. In the enteric nervous system and osteoclasts, TRAPPC9 localizes with components of the actin cytoskeleton, mediating the recruitment of actin‐regulatory proteins such as L‑plastin to facilitate proper podosome and actin ring formation. In neuronal models, deficiency of TRAPPC9 weakens the stability of the TRAPPII complex along neurites, leading to defective dendritic and axonal branching, diminished neural stem cell populations, and aberrant lipid droplet homeostasis that may further exacerbate neurodevelopmental and metabolic abnormalities."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "5", "end_ref": "8"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Ganeshwaran H Mochida, Muhammad Mahajnah, Anthony D Hill, et al. 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