{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n FAF1 (Fas‐associated factor 1) is a multifunctional regulatory protein whose diverse activities have been implicated in apoptosis, protein quality control, intracellular signaling, inflammation, and developmental processes. Initially identified as a Fas‐binding protein, FAF1 associates with components of the death‐inducing signaling complex—including Fas, FADD, and caspase‐8—to promote apoptotic cell death"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": ";."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": " In addition, FAF1 interacts with and antagonizes anti‐apoptotic pathways by sequestering NF‑κB p65 in the cytoplasm, thereby suppressing NF‑κB–mediated survival signaling"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": ", and it binds to Hsc70/Hsp70 to impair chaperone activity and enhance stress‐induced apoptotic signals."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Beyond its role in apoptosis, FAF1 functions as a scaffold that links polyubiquitinated proteins to the VCP/p97 complex via its ubiquitin‐associated (UBA) and UBX domains. This interaction facilitates the extraction and proteasomal degradation of ubiquitinated substrates, thereby maintaining protein homeostasis"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": ";"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "6"}]}, {"type": "t", "text": ";."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": " Structural studies have further revealed that the UBX domain of FAF1 binds to the N‑domain of p97 in a defined manner, underscoring its importance in the regulation of the ubiquitin–proteasome pathway."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "8"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n FAF1 also antagonizes key oncogenic and prosurvival signaling pathways. By acting as a scaffold for β‑TrCP, it enhances the polyubiquitination and subsequent degradation of β‑catenin, thereby dampening canonical Wnt signaling"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "9"}]}, {"type": "t", "text": ";."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "10"}]}, {"type": "t", "text": " In parallel, FAF1 facilitates the removal of the TGF‑β type II receptor from the cell surface through recruitment of the VCP/E3 ligase complex, limiting TGF‑β signaling and contributing to its metastasis‐suppressive function."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "11"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In the context of innate immunity, FAF1 has been shown to regulate antiviral responses by interfering with the polyubiquitination and aggregation of MAVS, thereby modulating downstream type I interferon signaling."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "12"}]}, {"type": "t", "text": " Moreover, its interaction with the pyrin domain of NLRP12 suggests a role in linking apoptotic and inflammatory cascades."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "13"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Finally, deregulation of FAF1 has been associated with pathological conditions. Reduced FAF1 expression is observed in certain cancers such as gastric carcinoma"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "14"}]}, {"type": "t", "text": ", and its accumulation has been linked to neurodegenerative events in Parkinson’s disease, where parkin‐mediated ubiquitination of FAF1 counteracts its pro‐death activity."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "15"}]}, {"type": "t", "text": " Alterations in FAF1 levels also appear to impact developmental processes, as evidenced by its disruption leading to cleft palate and jaw abnormalities in animal models."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "16"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Collectively, these studies support a model whereby FAF1 serves as a pivotal hub integrating apoptotic signals, proteasomal degradation, and multiple signaling pathways to maintain cellular homeostasis. Its multifunctional roles render it a potential therapeutic target in cancer, neurodegeneration, and developmental disorders.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Seung-Wook Ryu, Soo-Jin Lee, Min-Young Park, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Fas-associated factor 1, FAF1, is a member of Fas death-inducing signaling complex."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2003)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M302200200"}], "href": "https://doi.org/10.1074/jbc.M302200200"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "12702723"}], "href": "https://pubmed.ncbi.nlm.nih.gov/12702723"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Wenming Qin, Yi Shi, Botao Zhao, et al. 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