Research Projects

ATP-binding cassette (ABC) transporters are a large family of membrane proteins responsible for the translocation of various substrates across cell membranes, playing a central role in cellular homeostasis. Among the ABC family members, ABCA1, ABCA5, and ABCA7 are known for their involvement in lipid transport and cholesterol efflux, processes critical for cellular lipid homeostasis and cardiovascular health. Research on ABCA1 has demonstrated its essential function in exporting cholesterol and phospholipids to apolipoprotein A-I (apoA-I), forming nascent high-density lipoproteins (HDL), which protect against cardiovascular disease (CVD) by reducing cholesterol buildup in the arteries. Mutations in ABCA1, for example, are associated with Tangier disease, characterized by severe HDL deficiency and cholesterol accumulation in macrophages. In comparison, the research landscape for ABCA5 remains underexplored, even though it is a close homolog to ABCA1 and ABCA7. Preliminary studies suggest that ABCA5 may contribute to cellular cholesterol and lipid regulation, particularly in steroidogenic tissues and organs like the liver. Recent studies have shown ABCA5 expression correlating with lipid levels in cardiovascular cells, suggesting its potential as a mediator in lipid homeostasis and cholesterol efflux. However, despite its structural and sequence homology with ABCA1, ABCA5's mechanistic role in lipid transport and its significance in cardiovascular health remain undefined. Unlike ABCA1, whose structure-function relationship has been extensively studied via cryo-electron microscopy (cryo-EM) and mutagenesis studies, similar structural data for ABCA5 are scarce. This lack of detailed structural and functional understanding of ABCA5 presents a significant research gap. While some initial in silico studies and cellular expression profiles point to its role in cholesterol regulation, empirical evidence supporting this hypothesis is limited. The absence of high-resolution structural data has prevented a deeper understanding of how ABCA5 may facilitate cholesterol efflux or interact with lipid-binding proteins. Given ABCA5’s high expression in specific cell types and its role suggested by preliminary studies, a detailed exploration of its function in cholesterol handling could reveal new mechanisms for maintaining cellular lipid homeostasis. Furthermore, emerging studies in lipidomics and proteomics suggest that ABCA5 might interact with other proteins involved in lipid transport, such as lipid-transfer proteins and regulatory enzymes. Understanding these interactions could uncover novel pathways regulated by ABCA5, with potential implications for therapeutic targeting. Cross-linking mass spectrometry (XL-MS) and proximity-labeling techniques, combined with structural studies, could reveal a network of protein-protein interactions involving ABCA5, which would provide a more comprehensive view of its role within lipid metabolic pathways.