{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n ITM2A is a type II transmembrane protein that has emerged as a multifunctional regulator in a wide range of biological processes. In musculoskeletal tissues, ITM2A expression is elevated in osteoarthritic cartilage, and its tightly controlled expression appears to be critical for proper chondrogenesis and endochondral ossification. In mesenchymal progenitors, for example, higher ITM2A levels correlate with impaired chondrogenic differentiation, whereas its downregulation is associated with successful induction of the chondrogenic program."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "4"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n ITM2A expression is also modulated by key signaling pathways. Activation of the PKA–CREB axis up‐regulates ITM2A, and the protein in turn interferes with autophagic flux by interacting with the vacuolar ATPase, suggesting a role in regulating cellular homeostasis."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": " In cancer models, ITM2A functions as a tumor suppressor. Reduced ITM2A expression is observed in ovarian, breast, and cervical cancers, where its loss is associated with enhanced proliferation, impaired cell cycle arrest, and chemoresistance. Conversely, restoring ITM2A levels inhibits proliferation and can sensitize tumor cells to chemotherapy."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "6", "end_ref": "9"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In the immune system, ITM2A is elevated during positive selection of thymocytes and operates as a downstream target of GATA‐3, playing a modest role in T‐cell maturation and activation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "10"}]}, {"type": "t", "text": " Moreover, altered ITM2A expression in macrophages is linked to immune-mediated conditions such as ankylosing spondylitis, and differential expression in urinary cells may serve as a biomarker in kidney allograft rejection."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "12"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n ITM2A also has roles in cell differentiation beyond cartilage. In adipogenesis, endogenous ITM2A expression is transiently downregulated during differentiation of preadipocytes, and its knockdown significantly enhances adipogenic conversion, likely through stabilization of PPARγ protein."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "14"}]}, {"type": "t", "text": " In the myogenic lineage, ITM2A is regulated by extracellular matrix components such as fibromodulin and has been shown to interfere with both canonical and non‐canonical Hedgehog signaling by interacting with PTCH1 and destabilizing GLI transcription factors, ultimately affecting the timing of myogenic differentiation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "15"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Finally, emerging evidence points to a role for ITM2A in the central nervous system. Although its mRNA is highly enriched in brain microvessels, efforts to exploit ITM2A for targeted brain drug delivery remain preliminary."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "17"}]}, {"type": "t", "text": " Moreover, studies in different contexts, including height variation where ITM2A escapes X chromosome inactivation"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": "and observations in skeletal muscle from neuropathic models showing dynamic ITM2A regulation"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "18"}]}, {"type": "t", "text": ", further emphasize the diverse regulatory roles of ITM2A.\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Collectively, these findings indicate that ITM2A is a multifunctional protein influencing cell differentiation, autophagy, tumor suppression, and immune responses, thereby representing a potential biomarker as well as a therapeutic target in a variety of diseases."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "19"}]}, {"type": "t", "text": "\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Eric Steck, Stephane Boeuf, Jessica Gabler, et al. 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