Abcg2, also known as breast cancer resistance protein (BCRP), is an ABC transporter. It functions as a poly-specific efflux pump, playing a crucial role in protecting organisms from xenobiotics. It's involved in regulating oral bioavailability, and forms part of important barriers like the blood-brain, blood-testis, and maternal-fetal barriers. It is also expressed in stem cell populations, potentially contributing to xenobiotic protection [2].

In macrophages, Abcg2 exports itaconate from the cytosol to the extracellular space in an ATPase-dependent manner. Macrophages deficient in Abcg2-mediated itaconate export show elevated transcription factor TFEB-dependent lysosomal biogenesis and antibacterial innate immunity. In a mouse model of S. typhimurium infection, such deficiency in macrophages promotes antibacterial innate immune defense, suggesting that Abcg2-mediated itaconate export limits TFEB-dependent lysosomal biogenesis and antibacterial innate immunity in inflammatory macrophages [1].

In conclusion, Abcg2 is essential for protecting organisms from xenobiotics and regulating important physiological barriers. Its role in macrophages, as revealed by mouse models, shows its significance in antibacterial innate immunity. Understanding Abcg2 through gene-knockout models provides insights into potential therapeutic strategies for treating bacterial infections.