{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n Complement C1q‐like 1 (C1QL1) is a secreted protein member of the C1q family that plays multifaceted roles in both neural development and extracerebral processes. In the central nervous system, C1QL1 is released by specific projection neurons – for instance, climbing fibers in the cerebellum – where it binds with high affinity to the adhesion G protein‐coupled receptor BAI3 expressed on Purkinje cells. This interaction is critical for orchestrating synapse formation, refinement, and maintenance, thereby establishing precise synaptic connectivity and contributing to motor learning during development and adulthood."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "3"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In addition, C1QL1 is expressed in the sensory epithelium of the cochlea, where its localization in outer hair cells correlates with regions of heightened auditory sensitivity. This spatial expression pattern suggests a role in the maintenance of afferent synaptic contacts that underlie auditory signal transduction."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Beyond its neural functions, C1QL1 also exhibits proangiogenic properties. It stimulates endothelial cell migration and capillary tube formation through activation of ERK1/2 signaling pathways, indicating that it can influence vascular remodeling processes."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In pathological contexts, emerging evidence supports a role for C1QL1 in tumorigenesis. For example, elevated expression of C1QL1 in lung adenocarcinoma has been associated with enhanced cell growth, invasion, migration, and epithelial–mesenchymal transition (EMT), while recent studies also implicate C1QL1 as a glioma‐promoting factor in de novo gliomagenesis. These findings point to its potential as both a prognostic biomarker and a therapeutic target in cancer."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "6"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Finally, the observation that the C1QL1 transcript undergoes conserved RNA editing across vertebrate species suggests that its activity is finely tuned by post‐transcriptional modifications, which may further diversify its functional roles under physiological and pathological conditions."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "8"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Collectively, these studies illustrate that C1QL1 is a multifunctional signaling molecule central to synaptic organization in the brain, vascular remodeling, and the regulation of tumor cell behavior, highlighting its broad significance in health and disease.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Wataru Kakegawa, Nikolaos Mitakidis, Eriko Miura, et al. 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