{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n DYRK1A (dual‐specificity tyrosine phosphorylation‐regulated kinase 1A) is emerging as a pivotal regulator of neurodevelopment, cell cycle progression, and neuronal maintenance. It plays a major role in normal brain growth by modulating neuronal proliferation and differentiation; both overexpression and haploinsufficiency of DYRK1A are linked to profound changes in brain size and architecture, as evidenced by genetic models and patient studies."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": " In the context of Down syndrome, where an extra copy of the gene is present, increased DYRK1A dosage disrupts multiple signaling pathways. It cooperates with DSCR1 to impair NFAT (nuclear factor of activated T cells) nuclear translocation, thereby perturbing transcriptional circuits essential for proper development and angiogenic regulation, which may in part explain both the cognitive deficits and reduced incidence of certain solid tumors observed in these individuals."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n At the molecular level, DYRK1A phosphorylates a range of substrates—including cyclin D1, p27, and tau protein—affecting processes from cell cycle exit to synaptic maintenance. Phosphorylation of tau at specific residues (e.g., Thr212, Ser202, and Ser404) by DYRK1A is associated with its hyperphosphorylation and aggregation, linking increased DYRK1A activity to the early onset of Alzheimer’s–type neurodegeneration seen in Down syndrome and other tauopathies."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": " Moreover, DYRK1A’s kinase activity is crucial for promoting the nuclear export and subsequent degradation of cell cycle regulators, thereby facilitating premature neuronal differentiation—a process that may underlie some neurodevelopmental deficits."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In addition to its roles in cell cycle control and neurodegeneration, truncating mutations in DYRK1A have been linked to syndromic forms of intellectual disability and autism spectrum disorders, underscoring its nonredundant function in maintaining central nervous system homeostasis."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "9"}]}, {"type": "t", "text": " Collectively, these findings position DYRK1A as a central node that integrates developmental signaling, cell cycle regulation, and neuroprotective mechanisms, and they highlight its potential as a therapeutic target for conditions such as Down syndrome, Alzheimer’s disease, and other neurodevelopmental disorders.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Vassiliki Fotaki, Mara Dierssen, Soledad Alcántara, et al. 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