{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n Haspin is a serine/threonine kinase that plays a central role in the regulation of chromosome behavior during both mitosis and meiosis. By phosphorylating histone H3 at threonine‐3 (H3T3ph), Haspin creates a crucial docking site for the chromosomal passenger complex (CPC), which includes Aurora B kinase. This modification is essential for the centromeric accumulation of the CPC, thereby ensuring proper kinetochore–microtubule attachment, error correction, and faithful chromosome segregation during cell division."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "3"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In addition to its role in CPC recruitment, Haspin contributes to the maintenance of centromeric cohesion. It does so through interactions with cohesin regulators such as Pds5B, where binding of Haspin antagonizes the release factor Wapl and thereby safeguards cohesin retention at centromeres until anaphase."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": " Furthermore, during meiosis, inhibition of Haspin not only disrupts the normal distribution of the CPC along chromosomal arms but also perturbs the clustering of acentriolar microtubule-organizing centers, leading to aberrant spindle assembly and increased aneuploidy."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "6"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Recent structural and biochemical studies have further defined Haspin’s substrate recognition characteristics and expanded its repertoire by identifying novel substrates—such as the phosphorylation of macroH2A—thereby revealing a broader influence on chromatin regulation and gene expression."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "8"}]}, {"type": "t", "text": " Moreover, feedback regulation involving Aurora kinases has been documented, highlighting an intricate circuitry wherein Aurora B not only depends on Haspin for proper centromeric localization but also phosphorylates Haspin to enhance H3T3 phosphorylation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}, {"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In summary, Haspin integrates multiple signaling pathways by orchestrating CPC localization, sustaining centromeric cohesion, and regulating spindle assembly in mitosis and meiosis. These activities underscore its essential role in preserving genomic stability through precise control of chromosome segregation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}, {"type": "fg_f", "ref": "4"}, {"type": "fg_f", "ref": "8"}]}, {"type": "t", "text": " \n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Fangwei Wang, Jun Dai, John R Daum, et al. 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