Fbxl12, an F-box and leucine-rich repeat protein, is a component of the Skp1-Cul1-F box (SCF) E3 ubiquitin ligase complex. It plays crucial roles in multiple biological processes such as cell cycle regulation, differentiation, and DNA damage response [3,5,6]. It is involved in pathways like Fanconi anemia (FA) signaling, which is a key genomic maintenance pathway activated in response to replication stress [1].

In mouse models, FBXL12-null mice showed a differentiation block at the CD4⁺ CD8⁺ (DP)-CD4⁺ CD8⁻ or CD4⁻ CD8⁺ (SP) transition during T-cell differentiation, associated with ALDH3 accumulation in DP cells, indicating its cell-autonomous role in thymocyte maturation [4]. Most mice deficient in FBXL12 died during the embryonic or perinatal period due to abnormal placental development, with impaired formation of the junctional zone and ALDH3 accumulation in the placenta, highlighting its importance in trophoblast differentiation during placental development [2]. Depletion of FBXL12 exacerbated oncogene-induced replication stress and sensitized cancer cells to drug-induced replication stress by WEE1 inhibition, suggesting its potential as a therapeutic target in CYCLIN E-overexpressing cancers [1].

In conclusion, Fbxl12 is essential for T-cell and trophoblast differentiation, and plays a role in regulating replication recovery under stress conditions. The study of Fbxl12 knockout mouse models has provided insights into its functions in placental development and T-cell maturation, as well as its potential as a therapeutic target in certain cancers.