Fas-associated factor 1 (FAF1) is an evolutionarily conserved protein initially identified as a member of the FAS death-inducing signaling complex. It has several protein interaction domains and is involved in diverse biological processes. FAF1 plays important roles in normal development, neuronal cell survival, and is associated with pathways such as apoptosis, NFκB activity, ubiquitination, and proteasomal degradation. Genetic models, like knockout mice, are valuable for studying its functions [4].

In terms of specific findings, FAF1 can block ferroptosis by sequestering free polyunsaturated fatty acids (PUFAs) into a hydrophobic core, preventing their peroxidation and thus acting upstream of GPX4 [1]. Toxoplasma gondii can downregulate host FAF1 in a PI3K/AKT/FOXO1-dependent manner, which is essential for IRF3 nuclear translocation and parasite proliferation [2]. In pituitary corticotroph tumors, two FAF1 variants were identified in CD patients, though in vitro and in vivo studies did not clearly reveal an association with pituitary tumorigenesis [3]. Germline mutations in FAF1 are associated with hereditary colorectal cancer, as the variants encode unstable FAF1 proteins, increasing CRC cells' resistance to apoptosis and enhancing β-catenin and NF-κB activity [5]. Also, in a Parkinson's disease mouse model, targeting FAF1 with KM-819 restored autophagic flux for α-synuclein degradation [6].

In conclusion, FAF1 has diverse functions in multiple biological processes and diseases. Studies using knockout mouse models have been crucial in uncovering its roles in ferroptosis, pathogen-host interactions, pituitary tumorigenesis, colorectal cancer, and Parkinson's disease. These findings enhance our understanding of FAF1's biological functions and its implications in disease mechanisms, potentially guiding future therapeutic strategies.