{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n Alpha‐2‐macroglobulin (A2M) is a large, multifunctional glycoprotein best known for its broad‐spectrum protease inhibitory activity and its capacity to bind and regulate hormones, cytokines, and growth factors. By undergoing conformational change when its “bait” region is cleaved, A2M traps diverse proteases to limit tissue damage and modulate extracellular proteolysis."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": " In joint diseases, for example, A2M present in synovial fluid not only acts as a damage‐associated molecular pattern by engaging Toll‐like receptor 4 to induce inflammatory cytokine production"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": ", but also directly inhibits aggrecanases such as ADAMTS‐4 and ADAMTS‐5, thereby contributing to cartilage homeostasis."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In systemic inflammation, A2M functions as an acute‐phase protein whose plasma levels change in concert with other positive (e.g., fibrinogen, C-reactive protein) and negative (e.g., albumin) acute-phase proteins."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": " Moreover, elevated A2M levels in extravascular fluids have been used as markers for epithelial or blood–tissue barrier leak in conditions such as mucosal inflammation and neurodegeneration."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Beyond its classical role as a protease inhibitor, activated A2M (A2M*) also initiates cell signaling cascades. Receptor-recognized forms of A2M interact with surface‐expressed glucose-regulated protein 78 (GRP78), thereby stimulating PI3K/Akt, MAPK, and cytoskeletal kinase pathways that promote proliferative, antiapoptotic, and motility responses in cancer cells."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "7", "end_ref": "10"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Genetic association studies have evaluated sequence variations in the A2M gene with respect to neurodegenerative and age-related conditions—including senile systemic amyloidosis and Alzheimer’s disease as well as age-related macular degeneration—although these studies generally suggest that A2M variations contribute minimally to disease risk."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "11", "end_ref": "13"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Thus, A2M exemplifies a “moonlighting” protein whose classical role in protease inhibition interweaves with functions in inflammation, extracellular matrix protection, and intracellular signaling. These multifaceted actions underscore its clinical relevance both as a potential therapeutic target and as a biomarker in diverse pathophysiological settings.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Ahmed A Rehman, Haseeb Ahsan, Fahim H Khan "}, {"type": "b", "children": [{"type": "t", "text": "α-2-Macroglobulin: a physiological guardian."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Cell Physiol (2013)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1002/jcp.24266"}], "href": "https://doi.org/10.1002/jcp.24266"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "23086799"}], "href": "https://pubmed.ncbi.nlm.nih.gov/23086799"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Dong Hyun Sohn, Jeremy Sokolove, Orr Sharpe, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Plasma proteins present in osteoarthritic synovial fluid can stimulate cytokine production via Toll-like receptor 4."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Arthritis Res Ther (2012)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1186/ar3555"}], "href": "https://doi.org/10.1186/ar3555"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "22225630"}], "href": "https://pubmed.ncbi.nlm.nih.gov/22225630"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "Micky D Tortorella, Elizabeth C Arner, Robert Hills, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Alpha2-macroglobulin is a novel substrate for ADAMTS-4 and ADAMTS-5 and represents an endogenous inhibitor of these enzymes."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2004)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M313041200"}], "href": "https://doi.org/10.1074/jbc.M313041200"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "14715656"}], "href": "https://pubmed.ncbi.nlm.nih.gov/14715656"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Philippe Gervois, Robert Kleemann, Antoine Pilon, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Global suppression of IL-6-induced acute phase response gene expression after chronic in vivo treatment with the peroxisome proliferator-activated receptor-alpha activator fenofibrate."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2004)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M400346200"}], "href": "https://doi.org/10.1074/jbc.M400346200"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "14764586"}], "href": "https://pubmed.ncbi.nlm.nih.gov/14764586"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "Kathryn L Pothoven, James E Norton, Kathryn E Hulse, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Oncostatin M promotes mucosal epithelial barrier dysfunction, and its expression is increased in patients with eosinophilic mucosal disease."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Allergy Clin Immunol (2015)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.jaci.2015.01.043"}], "href": "https://doi.org/10.1016/j.jaci.2015.01.043"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "25840724"}], "href": "https://pubmed.ncbi.nlm.nih.gov/25840724"}]}, {"type": "r", "ref": 6, "children": [{"type": "t", "text": "Tomasz Jaworski, Benoit Lechat, David Demedts, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Dendritic degeneration, neurovascular defects, and inflammation precede neuronal loss in a mouse model for tau-mediated neurodegeneration."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Am J Pathol (2011)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.ajpath.2011.06.025"}], "href": "https://doi.org/10.1016/j.ajpath.2011.06.025"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "21839061"}], "href": "https://pubmed.ncbi.nlm.nih.gov/21839061"}]}, {"type": "r", "ref": 7, "children": [{"type": "t", "text": "Uma Kant Misra, Rohit Deedwania, Salvatore Vincent Pizzo "}, {"type": "b", "children": [{"type": "t", "text": "Activation and cross-talk between Akt, NF-kappaB, and unfolded protein response signaling in 1-LN prostate cancer cells consequent to ligation of cell surface-associated GRP78."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2006)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M511694200"}], "href": "https://doi.org/10.1074/jbc.M511694200"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "16543232"}], "href": "https://pubmed.ncbi.nlm.nih.gov/16543232"}]}, {"type": "r", "ref": 8, "children": [{"type": "t", "text": "Uma Kant Misra, Rohit Deedwania, Salvatore Vincent Pizzo "}, {"type": "b", "children": [{"type": "t", "text": "Binding of activated alpha2-macroglobulin to its cell surface receptor GRP78 in 1-LN prostate cancer cells regulates PAK-2-dependent activation of LIMK."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2005)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M414467200"}], "href": "https://doi.org/10.1074/jbc.M414467200"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "15908432"}], "href": "https://pubmed.ncbi.nlm.nih.gov/15908432"}]}, {"type": "r", "ref": 9, "children": [{"type": "t", "text": "Uma K Misra, Mario Gonzalez-Gronow, Govind Gawdi, et al. "}, {"type": "b", "children": [{"type": "t", "text": "The role of Grp 78 in alpha 2-macroglobulin-induced signal transduction. Evidence from RNA interference that the low density lipoprotein receptor-related protein is associated with, but not necessary for, GRP 78-mediated signal transduction."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2002)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M206174200"}], "href": "https://doi.org/10.1074/jbc.M206174200"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "12194978"}], "href": "https://pubmed.ncbi.nlm.nih.gov/12194978"}]}, {"type": "r", "ref": 10, "children": [{"type": "t", "text": "Uma Kant Misra, Mario Gonzalez-Gronow, Govind Gawdi, et al. "}, {"type": "b", "children": [{"type": "t", "text": "The role of MTJ-1 in cell surface translocation of GRP78, a receptor for alpha 2-macroglobulin-dependent signaling."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Immunol (2005)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.4049/jimmunol.174.4.2092"}], "href": "https://doi.org/10.4049/jimmunol.174.4.2092"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "15699139"}], "href": "https://pubmed.ncbi.nlm.nih.gov/15699139"}]}, {"type": "r", "ref": 11, "children": [{"type": "t", "text": "Maarit Tanskanen, Terhi Peuralinna, Tuomo Polvikoski, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Senile systemic amyloidosis affects 25% of the very aged and associates with genetic variation in alpha2-macroglobulin and tau: a population-based autopsy study."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Ann Med (2008)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1080/07853890701842988"}], "href": "https://doi.org/10.1080/07853890701842988"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "18382889"}], "href": "https://pubmed.ncbi.nlm.nih.gov/18382889"}]}, {"type": "r", "ref": 12, "children": [{"type": "t", "text": "J A Prince, L Feuk, S L Sawyer, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Lack of replication of association findings in complex disease: an analysis of 15 polymorphisms in prior candidate genes for sporadic Alzheimer's disease."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Eur J Hum Genet (2001)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1038/sj.ejhg.5200651"}], "href": "https://doi.org/10.1038/sj.ejhg.5200651"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "11436125"}], "href": "https://pubmed.ncbi.nlm.nih.gov/11436125"}]}, {"type": "r", "ref": 13, "children": [{"type": "t", "text": "Jonathan L Haines, Nathalie Schnetz-Boutaud, Silke Schmidt, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Functional candidate genes in age-related macular degeneration: significant association with VEGF, VLDLR, and LRP6."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Invest Ophthalmol Vis Sci (2006)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1167/iovs.05-0116"}], "href": "https://doi.org/10.1167/iovs.05-0116"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "16384981"}], "href": "https://pubmed.ncbi.nlm.nih.gov/16384981"}]}]}]}