Abcd4-KO Mouse

Abcd4, a member of the ATP-binding cassette transporter superfamily, is mainly known for its role in transporting vitamin B12 (cobalamin) from lysosomes to the cytosol [2,3,4,5]. This function is crucial as vitamin B12 is essential for red blood cell development and is likely involved in its metabolism. It may also be associated with pathways related to mammary gland development, as genes like Igfbp3, Ccl5, Tlr2, and Prlr, which are associated with MAPK, JAK-STAT, and PI3K-AKT pathways, are affected by Abcd4 [1].

In zebrafish, abcd4-knockdown led to abnormal red blood cells, fewer hemoglobinized cells, and impaired blood circulation, indicating its importance in red blood cell development. The amino-acid sequence related to vitamin B12 transport in zebrafish Abcd4 is highly conserved, and the mutant can be rescued with human ABCD4, suggesting a conserved role in vertebrates [2]. In mouse HC11 mammary epithelial cells, over-expression and knockdown of Abcd4 inhibited cell proliferation and promoted apoptosis, revealing its role in mammary gland development [1].

In conclusion, Abcd4 is essential for vitamin B12 transport and metabolism, which is crucial for red blood cell development. Its role in mammary gland development, as demonstrated by in vitro experiments in mouse mammary epithelial cells, shows its significance in mammalian reproductive-related processes. The gene knockout-like models in zebrafish and in vitro knockdown in mouse cells have provided valuable insights into Abcd4-related vitamin B12-deficiency anemia and mammary gland-associated functions.