{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nSNRNP70, also known as U1‐70K, is a central component of the U1 small nuclear ribonucleoprotein complex that mediates the very first step of pre–mRNA splicing. By directly recognizing the 5′ splice site, SNRNP70 establishes extensive RNA–protein and protein–protein interactions that stabilize the duplex formed between U1 snRNA and the pre–mRNA. Structural and biochemical analyses have shown that SNRNP70 assists in recruiting splicing factors such as SRSF1 and couples spliceosome assembly to transcription, thereby ensuring high‑fidelity mRNA processing. Dynamic regulation of these interactions through phosphorylation by kinases like CLK1 further refines splice site selection and the assembly of early spliceosomal complexes."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "7"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nPost‐translational modifications of SNRNP70 are pivotal for its function and regulation. Methylation of SNRNP70 at lysine 130 by enzymes such as SETMAR and regulated phosphorylation events help control its conformational state and binding properties. These modifications not only modulate its participation in spliceosome assembly and the maintenance of U1 snRNP abundance but also affect its ability to undergo dynamic phase transitions. In pathological conditions such as Alzheimer’s disease, aberrant modifications contribute to the formation of insoluble, cytoplasmic aggregates and perturb normal RNA splicing. Moreover, the role of SNRNP70 in nuclear retention of spliced noncoding transcripts further underscores its importance in RNA metabolism."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "8", "end_ref": "13"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn addition to its fundamental role in splicing, SNRNP70 is a prominent autoantigen in systemic autoimmune diseases such as systemic lupus erythematosus and mixed connective tissue disease. Apoptotic processing and altered phosphorylation of SNRNP70 expose immunodominant epitopes—primarily within its RNA recognition motif—that are targeted by B and T cell responses. Such autoimmune reactivity has been associated with diverse clinical manifestations, including neuropsychiatric involvement and thyroid dysfunction. SNRNP70’s additional role in maintaining the integrity of nuclear gems further links its normal function to the prevention of autoimmunity and underscores its significance in cellular homeostasis."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "14", "end_ref": "23"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Béatrice Spiluttini, Bo Gu, Praveen Belagal, et al. 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