{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nPACSIN1 is an F‐BAR domain–containing protein whose intrinsic ability to sculpt membranes has been implicated in multiple aspects of membrane remodeling. Its F‐BAR domain induces the formation of diverse tubule morphologies—including narrow, constricted, and vesiculating membranes—that are regulated by autoinhibition via its SH3 domain and relieved by interactions with partners such as dynamin. In addition, PACSIN1 displays structural flexibility and forms lateral assemblies that sense and bend membranes; such attributes are critical during ciliogenesis, where PACSIN1 helps drive the transition from the mother centriole to basal body and facilitates the formation of extracellular membrane channels."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "4"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn neuronal contexts, PACSIN1—also known as syndapin I—acts as a pivotal coordinator of synaptic structure and protein trafficking. It regulates activity‐dependent endocytosis and participates in shaping dendritic spines by directly interacting with postsynaptic scaffold proteins. Furthermore, PACSIN1 modulates neuronal protein conformations, exemplified by its role in facilitating the proximity between the N17 and polyproline domains of huntingtin, as well as its participation in tau‐dependent pathways that influence AMPA receptor trafficking and synapse strength. The phosphorylation state of PACSIN1 further tunes its lipid binding and membrane tubulation activities, thereby impacting neuronal morphogenesis."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "5", "end_ref": "9"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nOutside the nervous system, PACSIN1 functions as an adaptor molecule with significant implications in immune regulation and disease pathogenesis. In plasmacytoid dendritic cells, for instance, PACSIN1 is selectively expressed and required for robust Toll‐like receptor–mediated type I interferon production, and de novo genetic variants in PACSIN1 have been linked to aberrant interferon responses in systemic lupus erythematosus. Moreover, PACSIN1 activity can influence viral life cycles by downregulating viral components such as HCV p7, while in gastric cancer cells, its overexpression promotes lysosomal fusion and the selective autophagy of major histocompatibility complex class I molecules—processes that curtail antigen presentation and dampen CD8⁺ T‐cell–mediated antitumor immunity."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "10", "end_ref": "13"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Qi Wang, Marcos V A S Navarro, Gary Peng, et al. 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